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JUNE  1999 
VOLUME  44 
NUMBER  6 

ISSN  0020-1324-RECACP 


SPECIAL  ISSUE 

ARTIFICIAL  AIRWAYS 
PART  I 


A  MONTHLY  SCIENCE  JOURNAL 
44TH  YEAR— ESTABLISHED  1956 


History  of  Intubation,  Tracheotomy,  and 
Airway  Appliances 

Indications  for  Translaryngeal  Intubation 

Orotracheal  Intubation  Outside  the 
Operating  Room 

Humidification  for  Patients  with  Artificial 
Airways 

Nasotracheal  Intubation 

Airway  Management  in  Infants  and  Children 

Special  Purpose  Endotracheal  Tubes 


Methods  to  Avoid  Intubation 


"^^^^m 


ION 


^•^7^. 


\.f 


^'^A  V 


i^V -:-•« 


HAVE  RELIED  ON  THE  ACCURACY 
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effective  therapy. 

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that  has  stood  the  test  of  time  in  the  most 
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ttily  1 998}  &r)6  other  ttiought  leaders  L'se  the  Astech  Pealt  Flow  Meter  exclusively. 

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ORIENTATION  AND 
COIVIPETENCY  ASSURANCE 

MANUAL  FOR 


The  Orientation  and  Competency  Assurance  Manual  for  Respiratory 
Care  ensures  that  your  staff  receives  structured  orientation  and 
competence  thai  is  periodically  assessed  and  documented.  It 
provides  the  information,  assessment  tools,  and  models  necessary 
to  demonstrate  the  competence  of  employees  is  documented  according 
to  JCAHO  requirements.  This  manual  provides  you  with  the  resources 
and  examples  to  create  a  ct/stom/zec/ orientation  and  competency 
assurance  system  for  respiratory  care  services. 


•Initial  Assessment  and  Document  of  Employee 
Experience,  Education,  and  Credentials 

•Competency  Validation  in  Critical  Organizational 
System  Safety  Practices 

•Departmental  Orientation 

•  Orientation  and  Competency  Validation  for  General 
Respiratory,  Adult  Critical,  Neonatal/Pediatric 
Respiratory  Care,  Diagnostic  Testing, 

and  Age-Specific  Patient  Populations 

•Orientee  Progress  Evaluations 

•  Preceptor  Training  and  Competency  Validation 

•System  for  the  Selection,  Ongoing  Assessment, 
Maintenance,  Improvement  of  Skills, 
and  Competency 

•Construction  of  Clinical  Competency 
Checklists 


•  Improvement  of  Competency 
Assessment  Congruency 

•Reporting  of  Competence  Patterns  and 
Trends 

►Integration  of  Competency  Assessments 
with  In-Services  and  Continuing  Education 

•System  for  Linkage  of  Job  Description, 
Competency  Level,  Annual  Performance 
Evaluation,  and  Performance  Improvement 

•Appendix-Self-Learning  Module  for  Critical 
Organizational  System  Safety  Practices 

•Appendix-Orientation  and  Competency 
Validation  for  Multi-Skilling  and 
Cross-Training  in  Perinatal  Care 

•Appendix-Sample  Performance 
Evaluation  Instrument 


By  Daniel  Grady  MEd,  RRT;  Valerie  Lawrence,  RRT;  Tammy  Caliri,  RRT; 
and  Mitzi  Johnson,  RNC,  MSN.  258  Pages,  Binder  1997 

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I 


FOR  INFORMATION, 
CONTACT: 

AARC  Membership  or  Other  AARC 
Services 

American  Association  for 

Respiratory  Care 

11030  Abies  Ln 

Dallas  TX  75229-4593 

(972)  243-2272  •  Fax  (972)  484-2720 

http://www.aarc.org 

Therapist  Registration  or 
Technician  Certification 

National  Board  for  Respiratory 

Care 

8310Nieman  Rd 

Lenexa  KS  66214 

(913)  599-4200  •  Fax  (913)  541-0156 

http;//www.nbrc.org 

Accreditation  of  Education 
Programs 

Committee  on  Accreditation  for 

Respiratory  Care 

1248Harwood  Rd 

Bedford  TX  76021-4244 

(817)  283-2835  •  Fax  (817)  354-8519 

http://www.coarc.com 

Grants,  Scholarships,  Community 
Projects 

American  Respiratory  Care 

Foundation 

11030  Abies  Ln 

Dallas  TX  75229-4593 

(972)  243-2272  •  Fax  (972)  484-2720 

Government  Affairs  — 

Cheryl  West  MHA  (703-548-8506) 

State  Government  Affairs  — 

Jill  Eicher  WIPA  (703-548-8538) 
1225  King  St,  Second  Floor 
Alexandria  VA  22314 
Fax  (703)  548-8499 


RE/PIRATORy 
QiRE 


RESPIRATORY  CARE  (ISSN  0020-1324,  USPS  0489- 
190)  is  published  monthly  by  Daedalus  Enterprises  Inc.  at 
1 1030  Abies  Lane,  Dallas  TX  75229-4593.  for  the  Amer- 
ican Association  for  Respiratory  Care.  One  volume  is 
published  per  year  beginning  each  January.  Subscription 
rates  are  $75  per  year  in  the  US;  $90  in  all  other  countries 
(for  airmail,  add  $94). 

The  contents  of  the  Journal  are  indexed  in  Hospital  and 
Health  Administration  Index.  Cumulative  Index  to  Nurs- 
ing and  Allied  Health  Literature,  EMBASE/Exerpta  Med- 
ica,  and  RNdex  Library  Edition.  Abridged  versions  of 
RESPIRATORY  CARE  are  also  published  in  Italian, 
French,  and  Japanese,  with  permission  from  Daedalus  En- 
terprises Inc. 

Periodicals  postage  paid  at  Dallas  TX  and  at  additional 
mailing  offices.  POSTMASTER:  Send  address  changes  to 
RESPIRATORY  CaRE,  Membership  Office,  Daedalus  En- 
terprises Inc,  1 1030  Abies  Lane.  Dallas  TX  75229-4593. 

Printed  in  the  United  States  of  America 
Copyright  ©  1999,  by  Daedalus  Enterprises  Inc. 


JUNE   1999  /  VOLUME   44  /  NUMBER   6 


SPECIAL     ISSUE 

JOURNAL  CONFERENCE  ON 

ARTIFICIAL  AIRWAYS 

PART  I 

CO-CHAIRS 

Richard  D  Branson  RRT 
Charles  G  Durbin  Jr  MD 


CONFERENCE  PROCEEDINGS 


Foreword:  Artificial  Airways — The  1998  RESPIRATORY  CARE 

Journal  Conference 

by  Charles  G  Durbin  Jr— Charlottesville,  Virginia,  and  Richard  D  Branson — Cincinnati,  Ohio 


593 


The  History  of  Intubation,  Tracheotomy,  and  Airway  Appliances 

by  James  K  Stoller— Cleveland,  Ohio  595 

Indications  for  Translaryngeal  Intubation 

by  Dean  R  Hess — Boston,  Massachusetts  604 

Orotracheal  Intubation  Outside  the  Operating  Room: 

Anatomic  Considerations  and  Techniques 

by  William  E  Hurford — Boston,  Massachusetts  615 

Humidification  for  Patients  with  Artificial  Airways 

by  Richard  D  Branson — Cincinnati,  Ohio  6  3  U 

Nasotracheal  Intubation 

by  William  E  Hurford — Boston,  Massachusetts  643 

Issues  in  Airway  Management  in  Infants  and  Children 

by  Ann  E  Thompson — Pittsburgh,  Pennsylvania  650 

Special  Purpose  Endotracheal  Tubes 

by  J  Michael  Jaeger  and  Charles  G  Durbin  Jr — Charlottesville,  Virginia  661 

Methods  to  Avoid  Intubation 

by  Ray  Ritz — Boston,  Massachusetts  686 

BOOKS,  FILMS,  TAPES,  &  SOFTWARE 

SymBioSys  PFT  Pulmonary  Function  Test 
reviewed  by  Jacqueline  Chang — Seattle,  Washington 


Respiratory  Care  Pharmacology,  5th  Edition 
reviewed  by  Gregory  M  Susla — Bethesda,  Maryland 

Cardiopulmonary  Critical  Care,  3rd  Edition 
reviewed  by  Mark  T  Gladwin — Bethesda,  Maryland 

One  Minute  Asthma:  What  You  Need  to  Know,  4th  Edition 
reviewed  by  Yolanda  Mageto — Seattle,  Washington 


702 
702 
704 
704 


High  Frequency 

Intrapulmonary 

Percussion 

Ventilation 

1 

j^^^H 

■ 

^^^^^ 

Efficient 
Inexpensive 
Mucus 
Clearance 

■ 

WITHOUT  HIGH  FREQUENCY  OSCILLATION 


Factors  that  improve  mucus  clearance  rate  are 
important  for  patients  with  cystic  fibrosis,  COPD, 
and  atelectasis.  King  showed  that  high  frequency 
oscillation  enhanced  tracheal  mucus  clearance'^*. 
A  comparative  study  by  Castile  showed  that  chest 
physical  therapy  and  postural  drainage  produces 
sputum 
equivalent  to 
high  frequency 
oscillation  in 
patients  with 
cystic 
fibrosis'^'. 
The  diagram 
illustrates  the 
benefits  of 
high  frequency 
chest  wall 
oscillation 
seen  in 

intrapulmonary 
percussive 
ventilation. 
Since  the  time 
required  for 
effective 
mucus 
clearance  is 

an  important  compliant  factor,  the  most  desirable 
treatment  may  be  the  one  that  takes  the  shortest 
amount  of  time.  The  graph  compares  the  time 
required  for  treatment  with  three  common  modali- 
ties. The  PercussiveTech  HF  appears  to  be  the 
most  efficient  and  will  probably  improve  patient 
compliance  and  outcome. 

[1]    M.  King,  D.  M.  Phillips,  D.  Gross,  V.  Vartian,  H.  K.  Chang,  and  A. 
Zidulka:  Enhanced  Tracheal  Mucus  Clearance  with  High  Frequency 
Chest  Wall  Compression.  American  Review  of  Respiratory  Diseases 
1983,128:511-515. 

[2]    Castile,  R.;  Tice,  J.;  Flucke,  R.;  Filbrun,  D.;  Varekojis,  S.;  McCoy,  K. 
COMPARISON  OF  THREE  SPUTUM  CLEARANCE  METHODS  IN  IN- 
PATIENTS WITH  CYSTIC  FIBROSIS.  ABSTRACT  #:443  presented  in  20th 
Annual  North  America  Cystic  Fibrosis  Conference,  October  15-18,1 998, 
Montreal,  Quebec,  Canada.  (Pulmonary  Division,  Children's  Hospital, 
Ohio  State  University) 


WITH  HIGH  FREQUENCY  OSCILLATION 


[rway  Clearance 


PT»HF     PercussiveTech  HF^ 


The  first 

single  patient  use 
higli  frequency 
intrapulmonary  percussiv 
aerosol  ventilator 


Mucus  clearance 
(i.e.  cystic  fibrosis, 
COPD  and  atelectasis) 

High  frequency 

360  -  840  oscillation  per 

minute  (6 -14  Hz) 

High  aerosol  output 

Home  compressor 

Easy  to  set  up 


TIME  TO  CONDUCT  MUCUS  CLEARANCE  I'l 
WITH  AEROSOL  TREATMENT!^' 


P^ 

PercussiveTech  HF 
with  Aerosol'-' 

15Min. 

i 

1 

Flutter^" 
(~  9  MIn.) 

jBBH^ 

Traditional  CPT 
(~  20  Min.) 


0  10  20  30  40 

[1]  Based  on  an  independent  survey  of  respiratory  therapists  and  managers  conduct* 

at  the  national  1 998  American  Association  of  Respiratory  care  (AARC).  n=1 65 
[2]  Typical  PercussiveTech  treatment  combines  percussion  with  aerosol  treatment. 


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htlp:\\www.vortran.com  E-mail:  offlce@vortran.ci 


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ALSO 
IN  THIS  ISSUE 

AARC  Membership 
711                  Application 

■ 

568 

Abstracts  from 
Other  Journals 

720 

Advertisers  index 
&  Help  Lines 

720 

Author 
Index 

717 

Calendar 
of  Events 

713 

Manuscript 
Preparation  Guide 

709 

MedWatch 

708 

New  Products 
&  Services 

718 

Notices 

RE/PIRATORy 
OVRE 

A  Monthly  Science  Journal 
Established  in  1956 

The  Official  Journal  of  the 

American  Association  for 

Respiratory  Care 


I 


CONTINUED. 


CONTINUING  IN  JULY  1999 

proceedings  of  the 
Respiratory  Care 

JOURNAL  conference 

ON 

ARTIFICIAL  AIRWAYS 


CO-CHAIRS: 
RICHARD  D  BRANSON  RRT 
CHARLES  G  DURBIN  JR  MD 


American  Association  for  Respiratory  Care 

Your  Best  Bet. . . 

^^^^yi^ftt  International 

^  J  lii  Respiratory  Congress 


December  13-16,  1999 
Las  Vegas,  Nevada 


-4V. 


www.aarc.drg 


^•>.^f: 


Wejtmed  provided 

superior  aerosol  therapy  across 

the  care  continuum 


Electronic 


Maximizing 

delivery  of 

inhaled 

medications  to 

the  lungs 


MDILog^ 


The  device  provides  tlie  ability 
to  monitor  compliance  and 
record  true  delivery  and 
evaluate  patient  technique. 
These  features  make  it  the  ideal 
disease  management  tool  for 
asthma  and  COPD  patients. 


Circulaire^ 


Designed  for  inpatient  and 
at-home  use,  the  Circulaire's 
patented  distensible  drug 
reservoir  minimizes  waste 
while  it's  variable  resistor 
tailors  treatment  to  individual 
pediatric/ adult  patient  needs. 


HEARF''  Nebulizers 


The  high-output  extended 
aerosol  respiratory  therapy 
{HEART®!  system  is 
unsurpassed  in  delivering 
continuous  nebulization  therapy 
[CNT]  in  inpatient  and 
outpatient  settings. 


I  *  h 


Records  date  and  time  of  each  use  and 
evaluates  technique 

Reduces  lengths  of  stay  and  increases 
staff  productivity 

Transmits  data  for  analysis/ 
storage  with  fast  wireless 
communications 

Ideal  for  use  in  acute,  subacute,  pulmonary 
rehab,  physician's  office  and  home  settings 

Optimum  aerosol  particle  size  for  superior 
lung  deposition 

Ideal  for  protocol-based  concentrated  drug 
delivery 

Virtual  elimination  of  systemic  reaction  to 
beta  stimulators 

"Biofeedback"  gauges  encourage  maximum 
patient  effort 


The  HEART®  high-output  nebulizer  — 
up  to  8  hours  of  therapy 

The  MiniHEART®  low-flow  nebulizer  — 
up  to  10  hours  of  treatment 

The  low-cost  and  low-flow  UniHEARF*' 
nebulizer  —  ideal  for  Emergency 
Department  use 


A  leader  in  aerosol  drug  delivery  and  drug  management, 

providing  superior  results  through  productivity  gains  and  patient  outcomes 

across  the  care  continuum. 

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Westmed.lnc.    3351  E.  Hemisphere  Loop,  Tucson,  Arizona  85706    Phone:  800-724-2328    Fax:  520-294-6061    www.lungdepot.com 


I  shfil  PW  7n4fi8  Rev  02 


EDITORIAL  OFFICE 

600  Ninth  Avenue,  Suite  702 

Seattle  WA  98104 

(206)  223-0558 

Fax  (206)  223-0563 

www.rcjoumal.com 


EDITOR  IN  CHIEF 


A  Monthly  Science  Journal 
Established  in  1956 

The  Official  Journal  of  the 

American  Association  for 

Respiratory  Care 


David  J  Pierson  MD 
Harborview  Medical  Center 
University  of  Washington 
Seattle,  Washington 


ASSOCIATE  EDITORS 


Richard  D  Branson  RRT 
University  of  Cincinnati 
Cincinnati,  Ohio 


Charles  G  Durbin  Jr  MD 
University  of  Virginia 
Charlottesville,  Virginia 

EDITORIAL  BOARD 


Dean  R  Hess  PhD  RRT  FAARC 

Massachusetts  General  Hospital 
Harvard  University 
Boston,  Massachusetts 

James  K  Stoller  MD 

The  Cleveland  Clinic  Foundation 

Cleveland,  Ohio 


Thomas  A  Barnes  EdD  RRT 

Northeastern  University 
Boston,  Massachusetts 

Michael  J  Bishop  MD 

University  of  Washington 
Seattle,  Washington 

Bartolome  R  Celli  MD 

Tufts  University 
Boston,  Massachusetts 

Robert  L  Chatbum  RRT 
FAARC 

University  Hospitals  of  Cleveland 
Case  Western  Reserve  University 
Cleveland,  Ohio 

Luciano  Gattinoni  MD 

University  of  Milan 
Milan,  Italy 

John  E  Heffner  MD 

Medical  University  of  South  Carolina 
Charleston,  South  Carolina 

Mark  J  Heuhtt  MD 

University  of  Arkansas 
Little  Rock,  Arkansas 


SECTION  EDITORS 


Leonard  D  Hudson  MD 

University  of  Washington 
Seattle,  Washington 

Robert  M  Kacmarek  PhD  RRT 
FAARC 

Massachusetts  General  Hospital 
Harvard  University 
Boston,  Massachusetts 

Toshihiko  Koga  MD 
Koga  Hospital 
Kurume,  Japan 

Marin  HKollefMD 

Washington  University 
St  Louis,  Missouri 

Patrick  Leger  MD 

Clinique  Medicate  Edouard  Rist 
Paris,  France 

Neil  R  Maclntyre  MD  FAARC 
Duke  University 
Durham,  North  Carolina 

John  J  Marini  MD 

University  of  Minnesota 
St  Paul,  Minnesota 


Shelley  C  Mishoe  PhD  RRT 
FAARC 

Medical  College  of  Georgia 
Augusta,  Georgia 

Joseph  L  Rau  PhD  RRT 

Georgia  State  University 
Atlanta,  Georgia 

Catherine  SH  Sassoon  MD 

University  of  California  Irvine 
Long  Beach,  California 

Arthur  S  Slutsky  MD 

University  of  Toronto 
Toronto,  Ontario,  Canada 

Martin  J  Tobin  MD 

Loyola  University 
Maywood,  Illinois 


STATISTICAL  CONSULTANT 

Gordon  D  Rubenfeld  MD 

University  of  Washington 
Seattle,  Washington 


Hugh  S  Mathewson  MD 
Joseph  L  Rau  PhD  RRT 
Drug  Capsule 


Charles  G  Irvin  PhD 

Gregg  L  Ruppel  MEd  RRT  RPFT  FAARC 

PFT  Comer 


Richard  D  Branson  RRT 
Robert  S  Campbell  RRT 
Kittredge  's  Comer 


Jon  Nilsestuen  PhD  RRT  FAARC 
Ken  Hargett  RRT 
Graphics  Comer 


Patricia  Ann  Doorley  MS  RRT 
Charles  G  Durbin  Jr  MD 
Test  Your  Radiologic  Skill 


Abstracts 


Summaries  of  Pertinent  Articles  in  Other  Journals 


Control  of  House  Dust  Mite  in  Managing  Astlinia.  Effectiveness  of  Measures  Depends  on 
Stage  of  Asthma— Cloosterman  SG,  van  Schayck  OC.  BMJ  1999;318(7187):870. 

Fear  of  Hypercapnia  Is  Leading  to  Inadequate  Oxygen  Treatment — Lavery  GG.  BMJ  1999; 

318(7187):872. 

Pulmonary  and  Critical  Care  Medicine:  A  Peculiarly  American  Hybrid? — Tobin  MJ,  Hines 
E  Jr.  Thorax  1999;54(4):286-287. 

Ethical  and  Clinical  Issues  in  the  Use  of  Home  Non-Invasive  Mechanical  Ventilation  for  the 
Palliation  of  Breathlessness  in  Motor  Neurone  Disease — Polkey  MI,  Lyall  RA,  Davidson  AC, 
Leigh  FN,  Moxham  J.  Thorax  1999;54(4):367-371. 

Lung  Transplantation  (review)— Arcasoy  SM,  Kotloff  RM.  N  Engl  J  Med  1999;340(14):1081- 
1091. 

Negative-Pressure  Pulmonary  Edema  Associated  with  Saber-Sheath  Trachea — Jacka  MJ, 
PersaudSS.  Anesthesiology  1999;90(4):  1209-1211. 


Predicting  the  Need  for  Thoracoscopic  Evac- 
uation of  Residual  Traumatic  Hemothorax: 
Chest  Radiograph  is  Insufficient — Velmahos 
GC,  Demelriades  D,  Chan  L,  Tatevossian  R, 
Comwell  EE  3rd,  Yassa  N,  et  al.  J  Trauma 
1999;46(1):65. 

BACKGROUND:  The  early  removal  of  large 
residual  posttraumatic  hemothorax  by  videotho- 
racoscopy  is  increasingly  used  to  avoid  the  late 
sequelae  of  trapped  lung  and  empyema.  Plain 
chest  radiography  (CXR)  is  the  tool  most  fre- 
quently used  to  select  such  cases  for  operation. 
Our  recent  experience  has  demonstrated  that 
what  appears  to  be  a  large  retained  hemothorax 
on  CXR  may  turn  out  to  be  intrapulmonary  or 
extrapleural  conditions  not  amenable  to  thora- 
coscopic removal.  Our  objective  was  to  evalu- 
ate the  accuracy  of  CXR  in  detecting  signifi- 
cant residual  hemothorax  and  compare  its 
clinical  value  to  thoracic  computed  tomography 
(CT)  when  used  to  select  patients  for  thoraco- 
scopic evacuation.  METHODS:  All  patients  re- 
quiring tube  thoracostomy  for  traumatic  hemo- 
thorax were  prospectively  evaluated  during  a 
22-month  period  (n  =  703).  Patients  who,  on 
the  second  day  after  admission,  demonstrated 
opacification  on  CXR  involving  more  than  the 
costophrenic  angle  were  evaluated  by  thoracic 
computed  tomography  for  the  presence  of  un- 
drained  fiuid.  Second-day  CXR  (CXR^)  results 
were  compared  with  the  CT  findings.  Incorrect 
interpretation  was  defined  as  a  difference  of 
more  than  300  mL  between  the  two  readings. 
All  CXR-  and  CT  results  were  reviewed  in  the 
same  fashion  by  a  radiologist  blinded  to  the 


surgeon's  interpretations.  Data  on  injury  mech- 
anism, hemodynamic  status,  laboratory  values, 
interventions,  and  outcome  were  collected  pro- 
spectively. RESULTS:  Fifty-eight  patients  had 
clinically  significant  opacifications  on  CXR^. 
The  surgeon's  and  radiologist's  CXR^  interpre- 
tations were  incorrect  in  48  and  47%  of  the 
cases,  respectively.  The  CT  interpretations  by 
the  two  specialists  were  in  agreement  in  97%  of 
the  cases.  Management  that  would  have  been 
instituted  on  the  basis  of  CXR^  findings  was 
changed  in  18  cases  (31%).  Twelve  patients 
(21%)  required  early  thoracoscopic  evacuation 
of  undrained  collections.  There  was  good  cor- 
relation between  the  CT  estimation  and  the  tho- 
racoscopically  retrieved  amount  of  blood.  CON- 
CLUSION: Although  CXR  is  useful  as  a 
screening  tool,  it  cannot  be  used  to  reliably  se- 
lect patients  for  surgical  evacuation  of  retained 
traumatic  hemothorax.  Decision-making  should 
be  based  on  thoracic  CT  findings. 

Sampling  Intervals  to  Record  Severe  Hypo- 
tensive and  Hypoxic  Episodes  in  Anesthetised 
Patients — Derrick  JL,  Bassin  DJ.  J  Clin  Monit 
Comput  1998;I4(5):347. 

OBJECTIVE:  To  define  the  longest  sampling 
interval  which  will  faithfully  record  the  time 
course  of  episodes  of  severe  hypotension  and 
hypoxia  in  anestheti.sed  patients.  METHODS: 
Electronic  anesthetic  records  of  1501  patients 
were  analyzed  retrospectively  for  hypotension 
where  measured  systolic  blood  pressure  fell  to 
60  mmHg  or  less,  and  for  hypoxia  where  Spo^ 
fell  to  80%  or  less.  The  onset  and  offset  times, 


maximum  rate  of  change  and  spectral  content 
were  calculated  for  each  episode.  RESULTS: 
These  episodes  commonly  were  rapid  in  onset 
and  offset.  The  longest  sampling  interval  to  ac- 
curately represent  these  data  was  calculated  to 
be  36  s  for  invasive  blood  pressure  and  13  s  for 
pulse  oximetry.  CONCLUSIONS:  Our  current 
anesthetic  record  is  inadequate  to  record  many 
of  the  severe  changes  that  we  observed.  One 
minute  recording  intervals,  such  as  used  in  many 
electronic  record  keeping  systems,  are  too  slow 
to  capture  the  rapid  rates  of  change  seen,  and 
may  lead  to  the  assumption  that  an  episode  was 
not  recognized  promptly  or  that  treatment  was 
not  administered  in  a  timely  manner. 

A  Multiple-Dosing,  Placebo-Controlled 
Study  of  Budesonide  Inhalation  Suspension 
Given  Once  or  Twice  Daily  for  Treatment  of 
Persistent  Asthma  in  Young  Children  and 
Infants— Baker  JW,  Mellon  M,  Wald  J,  Welch 
M,  Cruz-Rivera  M,  Walton-Bowen  K.  Pediat- 
rics I999;103(2):414. 

Rationale.  Topical  antiinflammatory  medica- 
tions such  as  inhaled  corticosteroids  are  recom- 
mended for  therapy  of  asthma,  but  no  formula- 
tion suitable  for  administration  to  infants  and 
young  children  is  available  in  the  United  States. 
Methods.  This  was  a  12-week,  multicenter,  dou- 
ble-blind, randomized,  parallel-group  study 
comparing  the  efficacy  and  safety  of  four  dos- 
ing regimens  of  bude-sonide  inhalation  suspen- 
sion (BIS)  or  placebo  in  480  asthmatic  infants 
and  children  (64%  boys),  ages  6  months  to  8 
years,  with  moderate  persistent  asthma.  Approx- 


568 


Respiratory  Care  •  June  1999  Vol  43  No  6 


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Abstracts 


imately  30%  of  children  were  previously  on 
inhaled  corticosteroids  that  were  discontinued 
before  the  study.  Active  treatments  were  com- 
prised of  BIS  0.25  mg  once  daily  (QD),  0.25 
mg  twice  a  day  (BID),  0.5  mg  BID,  or  1.0  mg 
QD.  Efficacy  was  assessed  by  twice  daily  re- 
cording at  home  of  asthma  symptom  scores  and 
use  of  rescue  medication,  and  discontinuation 
from  the  study  because  of  worsening  asthma 
and/or  a  requirement  for  systemic  steroids.  Peak 
flow  measurements  were  recorded  twice  daily 
on  diary  and  spirometry  was  recorded  at  clinic 
visits  for  those  children  able  to  perform  these 
tests.  Safety  was  assessed  by  reported  adverse 
events  and  by  Cortisol  testing  (adrenocortico- 
tropic hormone  stimulation)  in  a  subset  of  pa- 
tients. Results,  Patients  enrolled  had  an  average 
duration  of  asthma  of  34  months;  the  mean 
asthma  symptom  score  was  approximately  1.3 
(scale  of  0-3).  All  dosing  regimens  with  BIS 
produced  statistically  significant  improvement 
in  various  clinical  efficacy  measures  for  asthma 
control  compared  with  placebo.  The  lowest  dose 
used,  0.25  mg  QD,  was  efficacious  but  with 
fewer  efficacy  parameters  than  seen  with  the 
other  doses  administered.  Separation  between 
active  treatment  and  placebo  in  daytime  and 
nighttime  symptom  scores  were  observed  by 
week  2  of  treatment  for  all  BIS  treatment  reg- 
imens. A  significant  increase  in  peak  flow  mea- 
surement was  observed  in  most  active  treat- 
ment groups  compared  with  placebo  in  the  subset 
of  children  able  to  do  pulmonary  function  test- 
ing. All  treatment  groups  showed  numerical  im- 
provement in  forced  expiratory  volume  in  1  sec- 
ond but  only  the  0.5-mg  BID  dose  was 
significantly  different  from  placebo.  Adverse 
events  for  the  entire  group  and  response  to  ad- 
renocorticotropic hormone  in  a  subgroup  of  chil- 
dren who  underwent  Cortisol  testing  before  and 
at  the  end  of  the  treatment  period  were  no  dif- 
ferent in  budesonide-treated  patients  in  com- 
parison to  placebo.  Conclusion.  Results  of  this 
study  demonstrate  that  BIS  is  effective  and  safe 
for  infants  and  young  children  with  moderate 
persistent  asthma  in  a  multiple  dose  range,  and 
that  QD  dosing  is  an  important  option  to  be 
considered  by  the  prescribing  physician. 

Statistical  Pattern  Detection  in  Univariate 
Time  Series  of  Intensive  Care  On-Line  Mon- 
itoring Data — Imhoff  M,  Bauer  M,  Gather  U, 
Lohlein  D.  Intensive  Care  Med  1998;24(12): 
1305. 

OBJECTIVES:  To  determine  how  different 
mathematical  time  series  approaches  can  be  im- 
plemented for  the  detection  of  qualitative  pat- 
terns in  physiologic  monitoring  data,  and  which 
of  these  approaches  could  be  suitable  as  a  basis 
for  future  bedside  time  series  analysis.  DESIGN: 
Off-line  time  series  analysis.  SETTING:  Surgi- 
cal intensive  care  unit  of  a  teaching  hospital. 
PATIENTS:  1 9  patients  requiring  hemodynamic 
monitoring  with  a  pulmonary  artery  catheter. 


INTERVENTIONS:  None.  MEASURE- 
MENTS AND  RESULTS:  Hemodynamic  data 
were  acquired  in  1-min  intervals  from  a  clinical 
information  system  and  exported  into  statistical 
software  for  further  analysis.  Altogether,  134 
time  series  for  heart  rate,  mean  arterial  pres- 
sure, and  mean  pulmonary  artery  pressure  were 
visually  classified  by  a  senior  intensivist  into 
five  patterns:  no  change,  outlier,  temporary  level 
change,  permanent  level  change,  and  trend.  The 
same  series  were  analyzed  with  low-order  au- 
toregressive  (AR)  models  and  with  phase  space 
(PS)  models.  The  resulting  classifications  from 
both  models  were  compared  to  the  initial  clas- 
sification. Outliers  and  level  changes  were  de- 
tected in  most  instances  with  both  methods. 
Trend  detection  could  only  be  done  indirectly. 
Both  methods  were  more  sensitive  to  pattern 
changes  than  they  were  clinically  relevant.  Es- 
pecially with  outlier  detection,  95%  confidence 
intervals  were  too  close.  AR  models  require 
direct  user  interaction,  whereas  PS  models  of- 
fer opportunities  for  fully  automated  time  series 
analysis  in  this  context.  CONCLUSION:  Sta- 
tistical patterns  in  univariate  intensive  care  time 
series  can  reliably  be  detected  with  AR  models 
and  with  PS  models.  For  most  bedside  prob- 
lems both  methods  are  too  sensitive.  AR  mod- 
els are  highly  interactive,  and  both  methods  re- 
quire that  users  have  an  explicit  knowledge  of 
statistics.  While  AR  models  and  PS  models  can 
be  extremely  useful  in  the  scientific  off-line 
analysis,  routine  bedside  clinical  use  cannot  yet 
be  recommended. 

Decision  Support  Issues  Using  a  Physiology 
Based  Score — Marcin  JP,  Pollack  MM,  Patel 
KM,  Ruttimann  UE.  Intensive  Care  Med  1998; 
24(12):  1299. 

OBJECTIVE:  As  physiology  based  assessments 
of  mortality  risk  become  more  accurate,  their 
potential  utility  in  clinical  decision  support  and 
resource  rationing  decisions  increases.  Before 
these  prediction  models  can  be  used,  however, 
their  performance  must  be  statistically  evalu- 
ated and  interpreted  in  a  clinical  context.  We 
examine  the  issues  of  confidence  intervals  (as 
estimates  of  survival  ranges)  and  confidence 
levels  (as  estimates  of  clinical  certainty)  by  ap- 
plying Pediatric  Risk  of  Mortality  III  (PRISM 
III)  in  two  scenarios:  (1)  survival  prediction  for 
individual  patients  and  (2)  resource  rationing. 
DESIGN:  A  non-concurrent  cohort  study.  SET- 
TING: 32  pediatric  intensive  care  units  (PICUs). 
PATIENTS:  10608  consecutive  patients  (571 
deaths).  INTERVENTIONS:  None.  MEA- 
SUREMENTS AND  RESULTS:  For  the  indi- 
vidual patient  application,  we  investigated  the 
observed  survival  rates  for  patients  with  low 
survival  predictions  and  the  confidence  inter- 
vals associated  with  these  predictions.  For  the 
resource  rationing  application,  we  investigated 
the  maximum  error  rate  of  a  policy  which  would 
limit  therapy  for  patients  with  scores  exceeding 


a  very  high  threshold.  For  both  applications,  we 
also  investigated  how  the  confidence  intervals 
change  as  the  confidence  levels  change.  The 
observed  survival  in  the  PRISM  111  groups  >28, 
>35,  and  >42  were  6.3,  5.3,  and  0%,  with  95% 
upper  confidence  interval  bounds  of  10.5,  13.0, 
and  13.3%,  respectively.  Changing  the  confi- 
dence level  altered  the  survival  range  by  more 
than  300%  in  the  highest  risk  group,  indicating 
the  importance  of  clinical  certainty  provisions 
in  prognostic  estimates.  The  maximum  error 
rates  for  resource  allocation  decisions  were  low 
(e.  g.,  29  per  100000  at  a  95%  certainty  level), 
equivalent  to  many  of  the  risks  of  daily  living. 
Changes  in  confidence  level  had  relatively  little 
effect  on  this  result.  CONCLUSIONS:  Predic- 
tions for  an  individual  patient's  risk  of  death 
with  a  high  PRISM  score  are  statistically  not 
precise  by  virtue  of  the  small  number  of  pa- 
tients in  these  groups  and  the  resulting  wide 
confidence  intervals.  Clinical  certainty  (confi- 
dence level)  issues  substantially  influence  out- 
come ranges  for  individual  patients,  directly  af- 
fecting the  utility  of  scores  for  individual  patient 
use.  However,  sample  sizes  are  sufficient  for 
rationing  decisions  for  many  groups  with  higher 
certainty  levels.  Before  there  can  be  widespread 
acceptance  of  this  type  of  decision  support,  phy- 
sicians and  families  must  confront  what  they 
believe  is  adequate  certainty. 

Discontinuous  Incremental  Threshold  Load- 
ing Test:  Measure  of  Respiratory  Muscle  En- 
durance in  Patients  with  COPD — Larson  JL, 
Covey  MK,  Berry  J,  Wirtz  S,  Alex  CG,  Matsuo 
M.  Chest  1999;115(1):60. 

STUDY  OBJECTIVE:  To  assess  the  discontin- 
uous incremental  threshold  loading  (DC-ITL) 
test  as  a  measure  of  respiratory  muscle  endur- 
ance for  patients  with  COPD  in  terms  of  per- 
ceived breathing  difficulty,  reliability,  and  va- 
lidity. DESIGN:  The  DC-ITL  test  was  repeated 
three  times  at  weekly  intervals  under  identical 
test  conditions.  SETTING:  Clinical  research  lab- 
oratory. PATIENTS:  Forty-eight  patients  with 
moderate  to  severe  COPD.  MEASUREMENTS 
AND  RESULTS:  Rating  of  perceived  breath- 
ing difficulty  (RPBD)  was  measured  at  the  end 
of  each  stage  of  the  DC-ITL  test  with  a  Borg 
category-ratio  scale.  The  maximal  inspiratory 
pressure  (PImax)  was  measured  before  and  af- 
ter the  DC-ITL  test.  Breathing  patterns  were 
measured  during  the  DC-ITL  test.  The  mean 
(±SD)  for  RPBD  at  the  maximal  load  was  6.3 
(3.1),  6.6  (2.8),  and  6.7  (2.7)  for  visits  one,  two, 
and  three,  respectively  (not  significant).  The 
mean  relative  maximal  load  for  the  DC-ITL  test 
(peak  mouth  pressure  as  a  percent  of  PImax)  at 
the  last  completed  stage  was  59±23%, 
62  ±20%,  and  63±  19%  for  visits  one,  two,  and 
three,  respectively  (not  significant).  Test-retest 
reliability  was  rl,2=0.82  and  r2,3=0.69  for  rel- 
ative maximal  load  and  rl,2  =  0.90  and 
r2,3  =  0.90  for  absolute  maximal  load  (peak 


570 


Respiratory  Care  •  June  1999  Vol  43  No  6 


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mouth  pressure).  Tidal  volume  decreased  (p  < 
0.01)  and  respiratory  rate  increased  (p  <  0.01) 
from  the  next-to-the-last  to  the  last  completed 
stage.  Plmax  decreased  after  the  DC-ITL  test 
(p  <  0.0 1 ).  CONCLUSIONS:  Moderate  breath- 
ing difficulty  was  experienced  during  the  DC- 
ITL  test.  The  test  was  reliable  and  the  results  of 
this  study  support  its  validity  as  a  measure  of 
respiratory  muscle  endurance. 


Sensitivity  and  Specificity  of  Radioisotope 
Right-Left  Shunt  Measurements  and  Pulse 
Oximetry  for  the  Early  Detection  of  Pulmo- 
nary Arteriovenous  Malformations — Thomp- 
son RD,  Jackson  J,  Peters  AM,  Dore  CJ,  Hughes 
JM.  Chest  1999;115(1):109. 

STUDY  OBJECTIVES:  To  assess  the  effec- 
tiveness of  pulse  oximetry  and  radioisotope  mea- 
surement of  right-to-left  (R-L)  shunt  for  the  early 
detection  of  pulmonary  arteriovenous  malfor- 
mations (PAVMs)  in  patients  with  hereditary 
hemorrhagic  telangiectasia  (HHT).  DESIGN: 
Patients  with  HHT  had  serial  measurements  of 
the  following:  (1)  arterial  oxygen  saturation 
(SaOj)  ''y  pulse  oximetry  in  erect  and  supine 
positions,  and  on  maximal  exercise  using  cycle 
ergometry;  (2)  quantitative  radioisotope  mea- 
surements of  R-L  shunt  using  IV  99mTc-la- 
beled  macroaggregates  of  albumin;  and  (3)  rou- 
tine pulmonary  function.  After  percutaneous 
transcatheter  embolization  of  all  PAVMs  with 


feeding  vessel  diameters  >  3  mm,  residual 
PAVMs  were  assessed  with  selective  digital  sub- 
traction pulmonary  angiography.  Using  postem- 
bolization  angiography  as  the  "gold  standard," 
S,Q,  and  radioisotope  shunt  measurements  after 
embolization  were  analyzed  retrospectively  us- 
ing logistic  regression  to  assess  the  ability  of 
each  test  to  predict  for  the  presence  of  residual 
PAVMs.  RESULTS:  Of  the  66  patients  in- 
cluded, 40  had  small  PAVMs  remaining  postem- 
bolization.  Using  univariate  logistic  regression, 
radioisotope  shunt  and  erect  saturation  showed 
a  significant  relationship  with  the  presence  of 
residual  PAVMs  (p=0.001,  0.005,  respective- 
ly). Erect  S„o,  ^  96%  had  73%  sensitivity  and 
35%  specificity  for  detecting  PAVMs.  Radio- 
isotope shunt  >3.5%  of  cardiac  output  had  87% 
sensitivity  and  61%  specificity  for  detecting 
PAVMs.  CONCLUSIONS:  These  results  con- 
firm that  noninvasive  measurements  are  useful 
in  the  screening  of  patients  with  HHT  for  the 
presence  of  PAVMs  without  need  for  angiog- 
raphy and  its  associated  risks,  and  that  radio- 
nuclide scanning  is  better  than  pulse  oximetry. 

Occupational  Asthma:  A  Longitudinal  Study 
on  the  Clinical  and  Socioeconomic  Outcome 
After  Diagnosis — Moscato  G,  Dellabianca  A, 
Perfetti  L,  Brame  B,  Galdi  E,  Niniano  R,  Pag- 
giaro  P.  Chest  1999;1 15(1):249. 

AIM:  To  evaluate  the  clinical  outcome  and  so- 
cioeconomic consequences  of  occupational 


asthma  (OA).  SUBJECTS  AND  METHODS: 
Twenty-five  patients  with  OA  both  to  high-  and 
low-molecular-weight  agents  (3  and  22,  respec- 
tively) confirmed  by  specific  inhalation  chal- 
lenge were  followed  up  for  1 2  months  after  the 
diagnosis.  Upon  diagnosis,  each  patient  received 
a  diary  on  which  to  report  peak  expiratory  flow 
rate  (PEER),  symptoms,  drug  consumption,  ex- 
penses directly  or  indirectly  related  to  the  dis- 
ease, as  well  as  information  regarding  personal 
socioeconomic  status.  At  each  follow-up  visit 
(1,  3,  6,  and  12  months),  the  patients  underwent 
clinical  examination,  spirometry,  methacholine 
(Mch)  challenge,  and  assessment  of  diary-de- 
rived parameters  and  socioeconomic  status. 
Asthma  severity  (AS)  was  classified  into  four 
levels,  based  on  symptoms,  drug  consumption, 
and  PEER  variability.  RESULTS:  At  1 2  months, 
13  patients  (group  A)  had  ceased  exposure;  the 
remaining  12  patients  (group  B)  continued  to 
be  exposed.  At  diagnosis,  FEV,  percent  and 
provocative  dose  causing  a  20%  fall  in  FEV, 
(PD20)  of  Mch  were  lower  in  group  A  than  in 
group  B;  patients  of  group  A  were  also  charac- 
terized by  significantly  higher  basal  AS  levels. 
At  12  months,  no  significant  variation  in  FEV, 
percent  or  PD20  was  found  for  either  group, 
while  AS  levels  improved  in  both  groups,  the 
change  being  more  marked  for  group  A  than 
group  B.  Pharmaceutical  expense  at  12  months 
significantly  (p  <  0.05)  decreased,  as  compared 
with  the  first  month,  in  group  A,  whereas  it 


Respiratory  Care  •  June  1999  Vol  43  No  6 


571 


Abstracts 


tended  to  increase  in  group  B.  In  group  A,  9  of 
1 3  subjects  had  reported  a  deterioration  of  their 
socioeconomic  status  as  compared  with  2  of  12 
in  group  B  (p  <  0.01).  A  significant  loss  of 
income  was  registered  in  patients  of  group  A 
(median  21,45,  25th  to  75th  percentiles  16.9  to 
25.8  Italian  liras  x  10(6)  on  the  year  preceding 
diagnosis  and  15.498,  10.65  to  21.087  Italian 
liras  X  10(6)  on  the  year  after  diagnosis;  p  < 
0.01),  whereas  no  significant  change  was  seen 
for  patients  in  group  B.  CONCLUSIONS:  In 
OA,  cessation  of  exposure  to  the  offending  agent 
results  in  a  decrease  in  asthma  severity  and  in 
pharmaceutical  expenses,  but  it  is  associated 
with  a  deterioration  of  the  individual's  socio- 
economic status  (professional  downgrading  and 
loss  of  work-derived  income).  There  appears  to 
be  a  great  need  for  legislation  that  facilitates  the 
relocation  of  these  patients. 


Tension  Fecopneumothorax  due  to  Colonic 
Perforation  in  a  Diapliragmatic  Hernia — 

Seelig  MH,  Klingler  PJ,  Schonleben  K.  Chest 
1999;1 15(0:288. 

A  traumatic  diaphragmatic  hernia  is  a  well- 
known  complication  following  blunt  abdominal 
or  penetrating  thoracic  trauma.  Although  the 
majority  of  cases  are  diagnosed  immediately, 
some  patients  may  present  later  with  a  diaphrag- 
matic hernia.  A  tension  fecopneumothorax, 
however,  is  a  rarity.  We  report  on  a  patient 
who,  2  years  after  being  treated  for  a  stab  wound 
to  the  chest,  presented  with  an  acute  tension 
fecopneumothorax  caused  by  the  incarceration 
of  the  large  bowel  in  the  thoracic  cavity  after  an 
intrathoracic  perforation.  The  etiology  and  man- 
agement of  this  condition  are  discussed. 


Airway  Obstruction  Arising  from  Blood  Clot: 
Three  Reports  and  a  Review  of  the  Litera- 
ture— Arney  KL,  Judson  MA,  Sahn  SA.  Chest 
1999;115(1):293. 

Airway  obstruction  due  to  presence  of  blood 
clot  occurs  in  a  variety  of  clinical  settings;  how- 
ever, it  is  not  always  preceded  by  hemoptysis. 
The  impact  on  respiratory  function  may  be  min- 
imal or  result  in  life-threatening  ventilatory  im- 
pairment. Three  illustrative  cases  and  a  com- 
prehensive literature  review  are  presented.  The 
presence  of  endobronchial  blood  clot  is  sug- 
gested by  the  clinical  and  radiographic  findings 
of  focal  airway  obstruction.  The  diagnosis  is 
established  by  direct  endoscopic  evaluation.  Ini- 
tial efforts  at  removal  of  the  airway  clot,  if 
warranted,  involve  lavage,  suctioning,  and  for- 
ceps extraction  through  a  flexible  bronchoscope. 
If  unsuccessful,  further  management  options  in- 
clude rigid  bronchoscopy,  Fogarty  catheter  dis- 
lodgment  of  the  clot,  and  topical  thrombolytic 
agents. 


Endemic  Fungal  Pneumonia  in  Immunocom- 
promised Patients — Conces  DJ  Jr.  J  Thorac 
Imaging  1999;14(1):1. 

The  endemic  fungi  Histoplasma  capsulatum, 
Coccidioides  immitis,  and  Blastomyces  derma- 
titidis  tend  to  reside  in  specific  geographic  re- 
gions. The  organisms  are  pathogenic  in  that  they 
are  able  to  produce  clinical  disease  in  both  im- 
munocompromised patients  and  in  patients  with 
normal  immunity.  These  organisms  have  a  va- 
riety of  clinical  presentations,  some  of  which 
typically  are  seen  in  the  normal  host  and  others 
that  are  primarily  encountered  in  persons  with 
abnormal  immunity.  Although  most  of  the  cases 
are  seen  in  endemic  regions,  they  may  occur  in 
persons  who  at  some  time  either  resided  in  or 
traveled  to  an  endemic  region. 


Expiratory  and  Inspiratory  Chest  Computed 
Tomography  and  Pulmonary  Function  Tests 
in  Cigarette  Smokers — Kubo  K,  Eda  S, 
Yamamoto  H,  Fujimoto  K,  Matsuzawa  Y,  Ma- 
ruyama  Y,  et  al.  Eur  Respir  J  1999;13(2):252- 
256. 

This  study  evaluated  small  airway  dysfunction 
and  emphysematous  destruction  of  lung  paren- 
chyma in  cigarette  smokers,  using  chest  expi- 
ratory high-resolution  computed  tomography 
(HRCT)  and  pulmonary  function  tests  (PFT). 
The  degree  of  emphysematous  destruction  was 
classified  by  visual  scoring  (VS)  and  the  aver- 
age HRCT  number  at  full  expiration/full  inspi- 
ration (E/I  ratio)  calculated  in  63  male  smokers 
and  1 0  male  nonsmokers  (group  A).  The  Brink- 
man  smoking  index  (BI),  defined  as  cigarettes 
X  day'  X  yrs,  was  estimated.  Sixty-three  smok- 
ers were  divided  into  three  groups  by  PFT:  group 
Bl  (n=7),  with  normal  PFT;  group  B2  (n=2I), 
with  diffusing  capacity  of  the  lung  for  carbon 
monoxide  (DL,CO)  >  80%  predicted,  forced 
expiratory  volume  in  one  second  (FEV,)  <  80% 
pred  and/or  residual  volume  (RV)  >  1 20%  pred; 
and  group  B3  (n=35),  with  DL,CO  <  80% 
pred,  FEV,  <  80%  pred  and/or  RV  >  120% 
pred.  Heavy  smokers  (BI  a  600)  (n = 48)  showed 
a  significant  increase  in  emphysema  by  both 
VS  and  E/I.  E/I  was  significantly  elevated  in 
both  group  B2  (mean±SD  0.95±0.05)  and  B3 
(0.96±0.06)  compared  with  group  Bl 
(0.89±0.03).  VS  could  not  differentiate  group 
B2  (3.9±5.0)  from  Bl  (1.1±1.6).  These  find- 
ings suggest  that  the  expiration/inspiration  ratio 
reflects  hyperinflation  and  airway  obstruction, 
regardless  of  the  functional  characteristics  of 
emphysema,  in  cigarette  smokers. 


Changes  in  Oxygenation  with  Inhaled  Nitric 
Oxide  in  Severe  Bronchopulmonary  Dyspla- 
sia— Banks  BA,  Seri  I,  Ischiropoulos  H,  Mer- 
rill J,  Rychik  J,  Ballard  RA.  Pediatrics  1999; 
103(3):610-618. 


Background.  Severe  bronchopulmonary  dyspla- 
sia (BPD),  which  is  associated  with  high  mor- 
tality and  morbidity,  is  thought  to  be  the  result 
of  mechanical,  inflammatory,  and  oxidant  in- 
jury to  the  immature  lung,  and  includes  the  de- 
velopment of  pulmonary  hypertension  with  vas- 
cular remodeling.  Methods.  A  phase  II  pilot 
study  was  conducted  to  determine  the  effect  of 
inhaled  nitric  oxide  (iNO)  on  oxygenation  in 
severe  BPD.  This  was  an  open-labeled,  non- 
controlled  trial  to  evaluate  safety  and  determine 
appropriate  dosing  for  a  future  randomized  con- 
trolled trial.  Infants  were  eligible  for  enroll- 
ment if  they  were  a  4  weeks  of  age  and  ven- 
tilator dependent  with  a  mean  airway  pressure 
of  >  10  cm  H2O  and  an  F,o,  of  >  0.45.  Study 
infants  received  iNO  (20  ppm)  for  72  hours, 
and  F,o,  was  adjusted  to  maintain  oxygen  sat- 
urations of  >92%.  Infants  who  had  a  a  15% 
reduction  in  F[Oj  after  72  hours  received  pro- 
longed treatment  with  low-dose  iNO,  weaning 
by  20%  every  3  days  as  tolerated.  Findings. 
Sixteen  preterm  infants  (23-29  weeks  of  ges- 
tation), age  1  to  7  months,  were  enrolled.  Eleven 
of  16  infants  had  a  significant  increase  in  P^qj 
after  1  hour  of  iNO  (median  change,  24  mm 
Hg;  range,  -15  to  59  mm  Hg;  P  <.01),  but  there 
was  no  significant  change  in  Paco,-  After  72 
hours  of  iNO,  1 1  infants  had  £15%  reduction 
in  Fioj,  and  7  of  the  1 1  had  a35%  reduction  (P 
<.  01).  Among  the  1 1  infants  who  responded  to 
iNO  after  72  hours,  10  had  a  sustained  im- 
provement in  oxygenation  throughout  their 
course  of  treatment  (duration,  8-90  days),  and 
ventilator  support  could  also  be  decreased.  No 
adverse  effects  from  iNO  (increased  methemo- 
globin,  bleeding,  or  increased  plasma  3-nitro- 
tyrosine)  were  observed.  Four  of  the  1 1  infants 
(36%)  who  responded  to  iNO  ultimately  weaned 
off  mechanical  ventilation  and  4  died,  whereas 
all  the  infants  who  failed  to  respond  to  iNO 
either  died  or  continue  to  require  mechanical 
ventilation.  Interpretation.  We  conclude  that  the 
use  of  low-dose  iNO  may  improve  oxygenation 
in  some  infants  with  severe  BPD,  allowing  de- 
creased Fjoj  and  ventilator  support  without  ev- 
idence of  adverse  effects.  Randomized  clinical 
trials  of  low-dose  iNO  for  BPD  are  wananted. 

Systemic  Air  Embolism  after  Lung  Trau- 
ma— Ho  AM,  Ling  E.  Anesthesiology  1999; 
90(2):564. 

Systemic  air  or  gas  embolism  has  been  increas- 
ingly recognized  as  a  complication  of  serious 
chest  trauma  and  often  presents  with  cata- 
strophic circulatory  and  cerebral  events.  The 
classic  findings  are  hemoptysis,  sudden  cardiac 
or  cerebral  dysfunction  after  initiation  of  PPV, 
air  in  retinal  vessels,  and  air  in  arterial  aspira- 
tions. The  clinician  must  be  wary  of  more  sub- 
tle presentations.  Several  diagnostic  tools  (TEE, 
Doppler,  CT)  can  detect  intracardiac  and  cere- 
bral air,  but  they  may  not  be  necessary  to  con- 
firm the  diagnosis  of  SAE.  Cessation  of  SAE  is 


572 


Respiratory  Care  •  June  1999  Vol  43  No  6 


Abstracts 


essential  for  successful  resuscitation.  In  those 
with  unilateral  lung  injury,  this  can  theoreti- 
cally be  achieved  by  isolating  and  ventilating 
the  noninjured  lung.  Sole  reliance  on  immedi- 
ate thoracotomy  for  hilar  clamping  to  stem  the 
flow  of  gas  emboli  is  a  concept  that  needs  to  be 
challenged.  Whether  airway  and  ventilation  in- 
terventions will  eliminate,  delay,  or  decrease 
the  need  for  thoracotomy  and  improve  the  prog- 
nosis of  SAE  remains  to  be  seen.  There  is  little 
reported  in  the  literature  regarding  such  inter- 
ventions. Airway  management  of  a  patient  at 
risk  for  SAE  should  include  a  technique  that 
can  selectively  ventilate  each  lung.  Patients  with 
bilateral  sources  of  SAE  may  benefit  from  the 
avoidance  of  high  airway  pressures.  Regional 
anesthesia  should  be  considered  when  appro- 
priate. HBOT  is  useful  in  managing  cerebral  air 
embolism  and  should  be  incorporated  as  soon 
as  possible.  Clinicians  involved  in  trauma  care 
must  be  familiar  with  SAE.  By  adopting  a  prob- 
lem-based solution  through  innovative  airway 
and  ventilation  management,  anesthesiologists 
may  significantly  alter  and  improve  the  mor- 
bidity and  mortality  rate  of  SAE  resulting  from 
chest  trauma. 

Decline  In  FEV,  Related  to  Smoking  Status 
in  Individuals  with  Severe  Alphal-Antitryp- 
sin  Deficiency — Piitulainen  E,  Eriksson  S.  Eur 
Respir  J  I999;13(2):247-251. 

Severe  alpha  I -antitrypsin  (AAT)  deficiency 
predisposes  to  emphysema  development.  Highly 
variable  rates  of  decline  in  lung  function  are 
reported  in  PiZZ  individuals.  The  annual  de- 
cline in  forced  expiratory  volume  in  one  second 
(FEV,;  A  FEV,)  was  analysed  in  relation  to 
smoking  status  in  a  cohort  of  608  adult  PiZZ 
individuals  included  in  the  Swedish  national 
AAT  deficiency  register.  A  FEV ,  was  analysed 
in  2 1 1  never-smokers,  in  35 1  exsmokers,  and  in 

46  current  smokers  after  performing  at  least 
two  spirometries  during  a  follow-up  time  of  I 
yr  or  longer  (median  5.5  yrs,  range  1-31).  The 
adjusted  mean  A  FEV,  in  never-smokers  was 

47  mL  X  yr"'  (95%  confidence  interval  (CI) 
41-53  mL  X  yr '),  41  mL  X  yr'  (95%  CI  36-48 
mL  X  yr')  in  exsmokers,  and  70  mL  x  yr"' 
(95%  CI  58-82  mL  x  yr')  in  current  smokers. 
A  dose-response  relationship  was  found  between 
cigarette  consumption  and  A  FEV,  in  current 
smokers  and  exsmokers.  In  never-smokers,  a 
greater  A  FEV ,  was  found  after  50  yrs  of  age 
than  before.  No  sex  differences  were  found  in 
A  FEV|.  In  conclusion,  among  PiZZ  individu- 
als, the  change  in  forced  expiratory  volume  in 
one  second  is  essentially  the  same  in  never- 
smokers  and  exsmokers.  Smoking  is  associated 
with  a  dose-dependent  increase  in  the  change  in 
forced  expiratory  volume  in  one  second. 

Relation  Between  Influenza  Vaccination  and 
Outpatient  Visits,  Hospitalization,  and  Mor- 
tality in  Elderly  Persons  with  Chronic  Lung 


Disease — Nichol  KL,  Baken  L,  Nelson  A.  Ann 
Intern  Med  I999;I30(5):397. 

BACKGROUND:  Influenza  vaccine  is  under- 
used in  groups  targeted  for  vaccination.  OB- 
JECTIVE: To  define  the  effects  of  influenza 
and  the  benefits  of  influenza  vaccination  in  el- 
derly persons  with  chronic  lung  disease.  DE- 
SIGN: Retrospective,  multiseason  cohort  study. 
SETTING:  Large  managed  care  organization. 
PATIENTS:  All  elderly  members  of  a  managed 
care  organization  who  had  a  previous  diagnosis 
of  chronic  lung  disease.  MEASUREMENTS: 
Outcomes  in  vaccinated  and  unvaccinated  per- 
sons for  the  1993-1994,  1994-1995,  and  1995- 
1996  influenza  seasons  were  compared  after  ad- 
justment for  baseline  demographic  and  health 
characteristics.  All  data  were  obtained  from  ad- 
ministrative databa.ses.  RESULTS:  Vaccination 
rates  were  greater  than  70%  for  each  season. 
Among  unvaccinated  persons,  hospitalization 
rates  for  pneumonia  and  influenza  were  twice 
as  high  in  the  influenza  seasons  as  they  were  in 
the  interim  (noninfluenza)  periods.  Influenza 
vaccination  was  associated  with  fewer  hospital- 
izations for  pneumonia  and  influenza  (adjusted 
risk  ratio,  0.48  [95%  CI,  0.28  to  0.82])  and  with 
lower  risk  for  death  (adjusted  odds  ratio,  0.30 
[CI,  0.21  to  0.43])  during  the  influenza  seasons. 
It  was  also  associated  with  fewer  outpatient  vis- 
its for  pneumonia  and  influenza  and  for  all  re- 
spiratory conditions.  CONCLUSIONS:  For  el- 
derly persons  with  chronic  lung  disease, 
influenza  is  associated  with  significant  adverse 
health  effects  and  influenza  vaccination  is  as- 
sociated with  substantial  health  benefits,  includ- 
ing fewer  outpatient  visits,  fewer  hospitaliza- 
tions, and  fewer  deaths.  Health  care  providers 
should  take  advantage  of  all  opportunities  to 
immunize  these  high-risk  patients. 

Effects  of  Viral  Lower  Respiratory  Tract  In- 
fection on  Lung  Function  in  Infants  with  Cys- 
tic Fibrosis — Hiatt  PW,  Grace  SC,  Kozinetz 
CA,  Raboudi  SH,  Treece  DG,  Taber  LH,  Piedra 
PA.  Pediatrics  I999;103(3):619. 

Objective.  To  determine  the  effect  of  respira- 
tory viral  infections  on  pulmonary  function  in 
infants  with  cystic  fibrosis  (CF)  after  the  respi- 
ratory virus  season  (October  through  March). 
Methods.  Recruitment  was  for  one  respiratory 
virus  season  during  a  3-year  span,  1988  to  1991, 
with  reenroUment  allowed;  22  infants  <2  years 
of  age  with  CF  (30  patient-seasons)  and  27  age- 
matched  controls  (28  patient-seasons)  partici- 
pated. Primary  outcome  variables  were  pre- 
season and  postseason  pulmonary  function  tests 
and  serology  for  viral  antibodies.  Twice-weekly 
telephone  calls  screened  for  respiratory  symp- 
toms. The  presence  of  respiratory  symptoms 
triggered  a  home  visit  and  an  evaluation  for 
upper  or  lower  (LRTI)  respiratory  tract  infec- 
tion. A  nasopharyngeal  sample  for  viral  culture 
was  performed  with  each  visit.  Results.  Con- 


trols and  CF  infants  each  had  a  mean  of  5.3 
acute  respiratory  illnesses;  CF  infants  were  four 
times  more  likely  to  develop  an  LRTI  com- 
pared with  controls  (odds  ratio,  4.6;  95%  con- 
fidence interval,  1.3  and  16.5).  Three  of  7  (43%) 
CF  infants  with  respiratory  syncytial  virus  in- 
fection (documented  by  culture)  required  hos- 
pitalization. Controls  had  no  as.sociation  be- 
tween respiratory  illness  and  postseason 
pulmonary  function.  For  CF  infants,  reduced 
postseason  maximal  flow  at  functional  residual 
capacity  (VmaxFRC)  was  associated  with  two 
interactions,  ie,  respiratory  syncytial  virus  in- 
fection and  LRTI,  and  male  sex  and  LRTI;  in- 
creased gas  trapping  (FRC)  was  associated  with 
an  interaction  between  respiratory  syncytial  vi- 
rus and  LRTI  and  day  care.  Postseason  pulmo- 
nary function  tests  were  obtained  a  mean  of  3. 
2  months  after  final  LRTI.  Conclusions.  Infants 
with  CF  incurring  respiratory  virus  infection 
are  at  significant  risk  for  LRTI,  for  hospitaliza- 
tion, and  for  deterioration  in  lung  function  that 
persists  months  after  the  acute  illness. 

Video-Assisted  Thoracoscopy  in  the  Treat- 
ment of  Pleural  Empyema:  Stage-Based  Man- 
agement and  Outcome — Cassina  PC.  Hauser 
M,  Hillejan  L,  Greschuchna  D,  Stamatis  G. 
J  Thorac  Cardiovasc  Surg  I999;l  I7(2):234. 

OBJECTIVE:  Despite  modem  diagnostic  meth- 
ods and  appropriate  treatment,  pleural  empy- 
ema remains  a  serious  problem.  Our  purpose 
was  to  assess  the  feasibility  and  efficacy  of  the 
video-assisted  thoracoscopic  surgery  in  the  man- 
agement of  nontuberculous  fibrinopurulent 
pleural  empyema  after  chest  tube  drainage  treat- 
ment had  failed  to  achieve  the  proper  results. 
METHODS:  We  present  a  prospective  selected 
single  institution  series  including  45  patients 
with  pleural  empyema  who  underwent  an  op- 
eration between  March  1993  and  December 
1996.  Mean  preoperative  length  of  conserva- 
tive management  was  37  days  (range,  8-82 
days).  All  patients  were  assessed  by  chest  com- 
puted tomography  and  ultrasonography  and  un- 
derwent video-assisted  thoracoscopic  debride- 
ment of  the  empyema  and  postoperative 
irrigation  of  the  pleural  cavity.  RESULTS:  In 
37  patients  (82%),  video-assisted  thoracoscopic 
debridement  was  successful.  In  8  cases,  decor- 
tication by  standard  thoracotomy  was  neces- 
sary. There  were  no  complications  during  vid- 
eo-assisted thoracic  operations.  The  mean 
duration  of  chest  tube  drainage  was  7.  1  days 
(range.  4-140  days).  At  follow-up  (n  =  35) 
with  pulmonary  function  tests,  86%  of  the  pa- 
tients treated  by  video-assisted  thoracic  opera- 
tion showed  normal  values;  14%  had  a  moder- 
ate obstruction  and  restriction  without 
impairment  ofexerci.se  capacity,  and  no  relapse 
of  empyema  was  observed.  CONCLUSIONS: 
Video-assisted  thoracoscopic  debridement  rep- 
resents a  suitable  treatment  for  fibrinopurulent 
empyema  when  chest  tube  drainage  and  fibrino- 


Respiratory  Care  •  June  1999  Vol  43  No  6 


573 


Abstracts 


lytics  have  failed  to  achieve  the  proper  results. 
In  an  early  organizing  phase,  indication  for  vid- 
eo-assisted thoracic  operation  should  be  con- 
sidered in  due  time  to  ensure  a  definitive  ther- 
apy with  a  minimally  invasive  intervention.  For 
pleural  empyema  in  a  later  organizing  phase, 
full  thoracotomy  with  decortication  remains  the 
treatment  of  choice. 

Theophylline  Therapy  for  Near-Fatal 
Cheyne-Stokes  Respiration.  A  Case  Report — 

Pesek  CA,  Cooley  R,  Narkiewicz  K,  Dyken  M, 
Weintraub  NL,  Somers  VK.  Ann  Intern  Med 
1999;I30(5):427. 

BACKGROUND:  Cheyne-Stokes  respiration  is 
characterized  by  periodic  breathing  that  alter- 
nates with  hypopnea  or  apnea.  OBJECTIVE: 
To  describe  the  effect  of  theophylline  on  near- 
fatal  Cheyne-Stokes  respiration.  DESIGN:  Case 
report.  SETTING:  Tertiary  referral  center.  PA- 
TIENT: A  48-year-old  diabetic  woman  with  a 
history  of  three  cardiorespiratory  arrests,  a  nor- 
mal coronary  arteriogram,  normal  left  ventric- 
ular function,  and  severe  Cheyne-Stokes  respi- 
ration. MEASUREMENTS:  Oxygen  saturation, 
intra-arterial  blood  pressure,  central  venous 
pressure,  chest  wall  movement,  electrocardiog- 
raphy, electromyography,  electroencephalogra- 
phy, electro-oculography,  minute  ventilation,  ar- 
terial blood  ga.ses,  and  serum  theophylline 
levels.  RESULTS:  After  intravenous  adminis- 
tration of  1 .2  mg  of  theophylline  at  0.6  mg/kg 
per  hour  (serum  level,  5.6  microg/mL),  both 
Cheyne-Stokes  respiration  and  oxygen  desatu- 
ration  were  markedly  attenuated.  After  infusion 
of  2.4  mg  of  theophylline  (serum  level,  1 1 .6 
microg/mL),  Cheyne-Stokes  respiration  re- 
solved completely.  No  change  was  seen  with 
placebo.  Cheyne-Stokes  respiration  did  not  re- 
cur during  outpatient  treatment  with  oral  the- 
ophylline. CONCLUSION:  Theophylline  may 
be  a  rapid  and  effective  therapy  for  life-threat- 
ening Cheyne-Stokes  respiration. 

Pulmonary  Airway  Resistance  with  the  En- 
dotracheal Tube  Versus  Laryngeal  Mask  Air- 
way in  Paralyzed  Anesthetized  Adult  Pa- 
tients— Berry  A,  Brimacombe  J,  Keller  C, 
Verghese  C.  Anesthesiology  1999;90(2):395. 

BACKGROUND:  The  hypothesis  that  airway 
resistance  is  less  with  the  laryngeal  mask  air- 
way than  with  the  endotracheal  tube  was  tested. 
METHODS:  Thirty-six  paralyzed,  anesthetized 
adult  patients  with  no  respiratory  disease  (Amer- 
ican Society  of  Anesthesiologists  physical  sta- 
tus 1-3;  age,  18-80  yr)  were  randomly  allo- 
cated (9  men,  9  women  in  each  group)  to  receive 
either  a  size-4  laryngeal  mask  airway  or  an  en- 
dotracheal tube  (men,  9-mm  ID;  women,  8-mm 
ID).  A  pulmonary  monitor  with  flow  transducer 
and  esophageal  balloon  was  used  to  measure 
peak  airway  pressure  and  mean  airway  resis- 
tance (device  resistance  plus  pulmonary  airway 


resistance)  at  three  different  tidal  volumes  (5, 
10,  and  15  mL/kg).  Device  resistance  was  mea- 
sured in  vitro  with  the  distal  end  of  the  endo- 
tracheal tube  or  laryngeal  mask  airway  open  to 
the  atmosphere  and  using  the  same  ventilator 
settings.  Pulmonary  airway  resistance  was  de- 
rived by  subtracting  the  mean  device  resistance 
from  the  mean  airway  resistance.  RESULTS: 
Peak  airway  pressure,  mean  airway  resistance, 
device  resistance,  and  pulmonary  airway  resis- 
tance were  greater  for  the  endotracheal  tube  (all 
P  <  O.OOOI).  CONCLUSIONS:  The  laryngeal 
mask  airway  triggers  less  bronchoconstriction 
than  does  the  endotracheal  tube  in  paralyzed 
anesthetized  adult  patients.  This  may  have  im- 
plications for  maintaining  intraoperative  pulmo- 
nary function  and  reducing  the  risk  for  atelec- 
tasis and  pulmonary  infection. 

A  Multicenter,  Randomized,  Controlled  Clin- 
ical Trial  of  Transfusion  Requirements  in 
Critical  Care.  Transfusion  Requirements  in 
Critical  Care  Investigators,  Canadian  Criti- 
cal Care  Trials  Group— Hebert  PC,  Wells  G, 
Blajchman  MA,  Marshall  J,  Martin  C,  Pagliar- 
ello  G,  et  al.  N  Engl  J  Med  I999;340(6):409. 

BACKGROUND:  To  determine  whether  a  re- 
strictive strategy  of  red-cell  transfusion  and  a 
liberal  strategy  produced  equivalent  results  in 
critically  ill  patients,  we  compared  the  rates  of 
death  from  all  causes  at  30  days  and  the  sever- 
ity of  organ  dysfunction.  METHODS:  We  en- 
rolled 838  critically  ill  patients  with  euvolemia 
after  initial  treatment  who  had  hemoglobin  con- 
centrations of  less  than  9.0  g  per  deciliter  within 
72  hours  after  admission  to  the  intensive  care 
unit  and  randomly  a.ssigned  418  patients  to  a 
restrictive  strategy  of  transfusion,  in  which  red 
cells  were  transfused  if  the  hemoglobin  concen- 
tration dropped  below  7.0  g  per  deciliter  and 
hemoglobin  concentrations  were  maintained  at 
7.0  to  9.0  g  per  deciliter,  and  420  patients  to  a 
liberal  strategy,  in  which  transfusions  were  given 
when  the  hemoglobin  concentration  fell  below 

10.0  g  per  deciliter  and  hemoglobin  concentra- 
tions were  maintained  at  10.0  to  12.0  g  per 
deciliter.  RESULTS:  Overall,  30-day  mortality 
was  similar  in  the  two  groups  (18.7  percent  vs. 
23.3  percent,  P=  0.1 1).  However,  the  rates  were 
significantly  lower  with  the  restrictive  transfu- 
sion strategy  among  patients  who  were  less 
acutely  ill  -  tho.se  with  an  Acute  Physiology 
and  Chronic  Health  Evaluation  II  score  of  £  20 
(8.7  percent  in  the  restrictive-strategy  group  and 

16.1  percent  in  the  liberal-strategy  group; 
P=0.03)  -  and  among  patients  who  were  less 
than  55  years  of  age  (5.7  percent  and  13.0  per- 
cent, respectively;  P=0.02),  but  not  among  pa- 
tients with  clinically  significant  cardiac  disease 
(20.5  percent  and  22.9  percent,  respectively; 
P=0.69).  The  mortality  rate  during  ho.spitaliza- 
tion  was  significantly  lower  in  the  restrictive- 
strategy  group  (22.3  percent  vs.  28.1  percent, 
P=0.05).  CONCLUSIONS:  A  restrictive  strat- 


egy of  red-cell  transfusion  is  at  least  as  effec- 
tive as  and  possibly  superior  to  a  liberal  trans- 
fusion strategy  in  critically  ill  patients,  with  the 
possible  exception  of  patients  with  acute  myo- 
cardial infarction  and  unstable  angina. 

Meta-Analysis  on  the  Association  Between 
Environmental  Tobacco  Smoke  (ETS)  Expo- 
sure and  the  Prevalence  of  Lower  Respira- 
tory Tract  Infection  in  Early  Childhood — Li 

JS,  Peat  JK,  Xuan  W,  Berry  G.  Pediatr  Pulmo- 
nol  I999;27(l):5. 

The  aim  of  this  study  was  to  obtain  quantitative 
information  from  published  data  on  the  associ- 
ation between  environmental  tobacco  smoke 
(ETS)  exposure  and  the  prevalence  of  serious 
lower  respiratory  tract  infections  (LRTI)  in  in- 
fancy and  eariy  childhood.  We  identified  21 
relevant  publications  on  the  relation  between 
ETS  and  the  prevalence  of  serious  LRTI  by 
reviewing  reference  lists  in  relevant  reports  and 
by  conducting  manual  and  computer  searches 
(Medline  database;  Dissertation  abstracts  index 
of  Xerox  University  Microfilms)  of  published 
reports  between  1966  and  1995.  Thirteen  stud- 
ies were  included  in  a  quantitative  overview 
using  random  effects  modeling  to  derive  pooled 
odds  ratios.  Sensitivity  analyses  were  conducted 
to  test  the  decision  rules  used  in  extracting  odds 
ratio  data.  The  results  of  community  and  hos- 
pital studies  are  broadly  consistent  and  show 
that  the  child  of  a  parent  who  smokes  is  at 
approximately  twice  the  risk  of  having  a  seri- 
ous respiratory  tract  infection  in  early  life  that 
requires  hospitalization.  This  association  was 
pronounced  in  children  younger  than  age  two 
and  diminished  after  the  age  of  two.  The  com- 
bined odds  ratio  for  hospitalization  for  lower 
respiratory  tract  infections  in  infancy  or  early 
childhood  is  l.93(95%CI  1.66-2.25);  the  com- 
bined odds  ratio  of  prevalence  of  serious  LRTI 
at  age  less  than  2  years,  between  0  and  6  years, 
and  between  3  and  6  years  were  1.71  (95%  CI 
1.33-2.20);  1.57  (1.28-1.91),  and  1.25  (0.88- 
1.78),  respectively.  There  was  no  evidence  of 
heterogeneity  across  the  studies  in  these  com- 
bined odds  ratios.  We  conclude  that  this  meta- 
analysis provides  strong  evidence  that  exposure 
to  ETS  causes  adverse  respiratory  health  out- 
comes such  as  either  a  serious  LRTI  or  hospi- 
talization for  LRTI.  New  public  health  cam- 
paigns are  urgently  needed  to  discourage 
smoking  in  the  presence  of  young  children. 

Adjudicating  Ventilator-Associated  Pneumo- 
nia in  a  Randomized  Trial  of  Critically  III 
Patients — Cook  D,  Walter  S,  Freilag  A,  Guyatt 
G,  Devitt  H,  Meade  M,  et  al.  J  Crit  Care  1998; 
13(4):  1 59. 

PURPOSE:  The  purpose  of  this  study  was  to 
evaluate  an  adjudication  strategy  for  diagnos- 
ing ventilator-associated  pneumonia  (VAP)  in  a 
randomized  trial.  MATERIALS  AND  METH- 


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Respiratory  Care  •  June  1999  Vol  43  No  6 


It  twists.  It  turns.  It  pivots.  And  ttiat's  just  the  monitor! 
The  Venturi®  ventilator  was  designed  to  adapt  to  the 
needs  of  both  the  patient  and  the  clinician. 

Its  flat  panel  monitor  provides  the  clinician  with  a 
large,  color,  flexible  display  showing  all  pertinent 
parameters  and  waveforms. 

But  there's  more  to  the  Venturi  than  just  the  monitor. 
The  Venturi  is  ahead  of  its  time,  providing  state-of- 
the-art  features  like  "smart"  software  that  continu- 
ously adapts  to  the  patient's  changing  breathing 
demands.  The  Patient  Simulator  allows  the  clinician 
to  evaluate  the  effect  of  proposed  changes  to 


ventilator  settings  before  they  are  applied  to  the 
patient.  And  the  Exhalation  Assist  feature  helps  the 
patient  overcome  ainvay  resistance  and  achieve  a 
more  rapid  and  complete  exhalation. 

Plus,  the  advanced  data  management  system 
provides  a  look  back  at  patient  history  and  provides 
a  side-by-side  comparison  with  current  patient 
information. 

Take  a  decidedly  different  look  at  ventilator  data  with 
the  Venturi  Ventilator.  The  new  generation  of  ventilator 
technology.  For  more  infomiation,  call  us  at 
800-337-9936. 


CARDIOPULMONARY    CORP. 

200  Cascade  Blvd.,  Milford,  CT  06460 
(203)877-1999    (800)337-9936 


Circle  108  on  reader  service  card 


Abstracts 


ODS:  In  a  double-blind  trial  of  sucralfate  ver- 
sus ranitidine,  one  of  four  pairs  of  adjudicators 
examined  each  case  of  clinically  suspected  VAP. 
Nurse  and  physician  notes  and  all  relevant  lab- 
oratory data  were  allocated  to  each  adjudication 
pair  in  groups  of  five  patients.  Each  reader  in 
the  pair  decided  whether  the  patient  had  VAP; 
differences  were  resolved  by  consensus  discus- 
sion. RESULTS:  The  overall  unadjusted  study 
odds  ratio  for  VAP  was  0.82  (P  =  0.21)  rep- 
resenting a  trend  toward  less  pneumonia  with 
sucralfate  compared  with  ranitidine.  The  odds 
ratio  adjusted  for  adjudication  pair  was  0.85 
(P  =  0.27).  The  proportion  of  charts  adjudi- 
cated as  VAP  positive  among  pairs  ranged  from 
50%  to  92%;  crude  agreement  between  readers 
in  each  pair  varied  from  50%  to  82%.  When 
adjudicators  disagreed,  the  final  consensus  was 
split  evenly  between  the  two  adjudicators'  ini- 
tial opinions  in  two  pairs;  in  the  other  two  pairs, 
the  final  decision  reflected  one  dominant  initial 
opinion.  Personnel  time  to  adjudicate  all  pa- 
tients with  a  suspicion  of  VAP  was  74  days. 
CONCLUSIONS:  Though  adjudication  of  out- 
comes such  as  VAP  is  time-consuming,  consis- 
tent decision-making  requires  strict  criteria, 
training,  and  calibration.  Patients  should  be  as- 
signed to  adjudication  teams  through  random 
allocation. 

A  Lung  Ultrasound  Sign  Allowing  Bedside 
Distinction  Between  Pulmonary  Edema  and 
COPD:  The  Comet-Tail  Artifact— Lichten- 
stein  D,  Meziere  G.  Intensive  Care  Med  1998; 
24(12):1331. 

OBJECTIVE:  Acute  cardiogenic  pulmonary 
edema  and  exacerbation  of  chronic  obstructive 
pulmonary  disease  (COPD)  can  have  a  similar 
clinical  presentation,  and  X-ray  examination 
does  not  always  solve  the  problem  of  differen- 
tial diagnosis.  The  potential  of  lung  ultrasound 
to  distinguish  these  (wo  disorders  was  assessed. 
DESIGN:  Prospectiveclinical  .study.  SETTING: 
The  medical  ICU  of  a  university-affiliated  teach- 
ing hospital.  PATIENTS:  We  investigated  66 
consecutive  dyspneic  patients:  40  with  pulmo- 
nary edema  and  26  with  COPD.  In  addition,  80 
patients  without  clinical  and  radiologic  respira- 
tory disorders  were  studied.  MEASURE- 
MENTS: The  sign  studied  was  the  comet-tail 
artifact  arising  from  the  lung  wall  interface,  mul- 
tiple and  bilaterally  dis.seminated  to  the  antero- 
lateral chest  wall.  RESULTS:  The  feasibility 
was  100%.  The  length  of  the  examination  was 
always  under  1  min.  The  described  pattern  was 
present  in  all  40  patients  with  pulmonary  edema. 
It  was  absent  in  24  of  26  cases  of  COPD  as  well 
as  in  79  of  80  patients  without  respiratory  dis- 
orders. The  sign  studied  had  a  .sensitivity  of 
100%  and  a  specificity  of  92%  in  the  diagnosis 
of  pulmonary  edema  when  compared  with 
COPD.  CONCLUSIONS:  With  a  described  pat- 
tern present  in  100%  of  the  cases  of  pulmonary 
edema  and  absent  in  92%  of  the  cases  of  COPD 


and  in  98.75%  of  the  normal  lungs,  ultrasound 
detection  of  the  comet-tail  artifact  arising  from 
the  lung-wall  interface  may  help  distinguish  pul- 
monary edema  from  COPD. 


A  Randomized  Study  Assessing  the  System- 
atic Search  for  Maxillary  Sinusitis  in  Naso- 
tracheally  Mechanically  Ventilated  Patients: 
Influence  of  Nosocomial  Maxillary  Sinusitis 
on  the  Occurrence  of  Ventilator-Associated 
Pneumonia — Holzapfel  L,  Chastang  C,  Dem- 
ingeon  G,  Bohe  J,  Piralla  B,  Coupry  A.  Am  J 
Respir  Cnt  Care  Med  1999  Mar;  1 59(3): 
695-701. 

The  objective  of  this  randomized  study  was  to 
compare  the  occurrence  of  nosocomial  pneu- 
monia in  nasolracheally  intubated  patients  who 
were  randomly  allocated  either  to  a  systematic 
search  of  sinusitis  by  CT  scan  (study  group)  or 
not  (control  group).  A  total  of  399  patients  were 
included:  272  male  and  127  female;  mean  age, 
61  ±  17  yr;  SAPS:  12.6  ±  4.9.  The  study  group 
consisted  of  199  patients  and  the  control  group 
consisted  of  200.  In  the  study  group,  sinus  CT 
scans  were  performed  in  case  of  fever  at  Days 
4  and  8  and  then  every  7  d.  Nosocomial  sinus- 
itis was  defined  as  follows:  fever  of  a  38  de- 
grees C,  radiographic  (sinusal  air-fluid  level  or 
opacification  on  CT  scan)  signs,  and  presence 
of  purulent  aspirate  from  the  involved  sinus 
puncture  with  S:  10"*  cfu/mL.  Patients  with  si- 
nusitis received  sinus  lavage  and  intravenously 
administered  antibiotics.  In  the  study  group,  80 
patients  experienced  nosocomial  sinusitis.  In  the 
control  group,  no  patient  was  treated  for  a  si- 
nusitis. Ventilator-associated  bronchopneumo- 
nia (VAP)  was  ob.served  in  88  patients:  37  in 
the  study  group  ( 1  mo  Kaplan-Meier  estimate, 
34%)  versus  51  in  the  control  group  (I  mo 
Kaplan-Meier  estimate,  47%);  (p  =  0.02,  log- 
rank  test;  relative  risk  [RR]  =  0.61;  95%  con- 
fidence interval  [CI],  0.40  to  0.93).  Two  months 
overall  mortality  was  estimated  at  36%  in  the 
study  group  versus  46%  in  the  control  group 
(p  =  0.03,  log-rank  test;  RR  =  0.71;  95%  CI, 
0.52  to  0.97).  We  conclude  that  the  occurrence 
of  VAP  in  patients  undergoing  prolonged  me- 
chanical ventilation  via  a  nasotracheal  intuba- 
tion can  be  prevented  by  the  systematic  search 
and  treatment  of  nosocomial  sinusitis.  The  ef- 
fect on  mortality  should  be  confirmed.  See  the 
related  editorial:  Assessment  of  Fever  in  the 
Intensive  Care  Unit:  Is  the  Answer  Just  Be- 
yond the  Tip  of  Our  Nose?  Hall  J .  Am  J  Respir 
Crii  Care  Med  l999;159(3}:693-694. 


Quality  of  Life  Assessment  afler  Patient  Ed- 
ucation in  a  Randomized  Controlled  Study 
on  Asthma  and  Chronic  Obstructive  Pulmo- 
nary Disease — Gallefoss  F,  Bakke  PS,  Rsgaard 
PK.  Am  J  Respir  Crit  Care  Med  1999  Mar; 
159(3):812-8I7. 


The  effect  of  patient  education  in  patients  with 
asthma  and  Chronic  Obstructive  Pulmonary  Dis- 
ease (COPD)  on  health-related  quality  of  life 
(HRQoL)  is  not  previously  investigated  using 
the  St.  George's  Respiratory  Questionnaire 
(SGRQ).  We  randomly  allocated  at  our  out- 
patient clinic  78  asthmatics  and  62  patients  with 
COPD  to  either  a  control  or  an  intervention 
group.  Intervention  consisted  of  two  2-h  group 
sessions  and  one  to  two  individual  sessions  each 
by  a  nurse  and  a  physiotherapist.  A  self-man- 
agement plan  was  developed.  Baseline  quality 
of  life  assessment  showed  comparable  scores 
independent  of  treatment  groups  among  asth- 
matics and  patients  with  COPD,  but  statisti- 
cally significantly  better  scores  (p  <  0.05)  for 
the  educated  asthma  group  after  12  mo  com- 
pared with  the  control  group.  This  aligned  with 
the  12-mo  SGRQ  assessment,  which  revealed 
better  symptoms,  activity,  impact,  and  total 
scores  by  1 1  (p  <  0.02),  15  (p  <  0.01),  19  (p  < 
0.001),  and  16  (p  <  0.001)  units,  respectively. 
Patient  education  among  asthmatics  increased 
the  FEV,  by  a  mean  value  of  6.1%  (SD,  12) 
compared  with  the  control  group  (p  <  0.05). 
Education  among  patients  with  COPD  did  not 
indicate  a  significant  increase  in  HRQoL  as  mea- 
sured by  the  SGRQ  or  increased  FEV,.  We 
conclude  that  patient  education  increased 
HRQoL  and  FEV,  among  asthmatics,  but  not 
among  patients  with  COPD. 

Aerobic  and  Strength  Training  in  Patients 
with  Chronic  Obstructive  Pulmonary  Dis- 
ease—  Bernard  S,  Whittom  F,  Leblanc  P.  Jobin 
J,  Belleau  R,  Berube  C,  et  al.  Am  J  Respir  Crit 
Care  Med  1999  Mar;l59(3):896-90I. 

The  purpose  of  this  study  was  to  evaluate 
whether  strength  training  is  a  useful  addition  to 
aerobic  training  in  patients  with  chronic  ob- 
structive pulmonary  disease  (COPD).  Forty-five 
patients  with  moderate  to  severe  COPD  were 
randomized  to  12  wk  of  aerobic  training  alone 
(AERO)  or  combined  with  strength  training 
(AERO  -I-  ST).  The  AERO  regimen  consisted 
of  three  weekly  30-min  exercise  sessions  on  a 
calibrated  ergocycle,  and  the  ST  regimen  in- 
cluded three  series  of  eight  to  10  repetitions  of 
four  weight  lifting  exercises.  Measurements  of 
peripheral  muscle  strength,  thigh  muscle  cross- 
sectional  area  (MCSA)  by  computed  tomo- 
graphic scanning,  maximal  exercise  capacity, 
6-min  walking  distance  (6  MWD),  and  quality 
of  life  with  the  chronic  respiratory  question- 
naire were  obtained  at  baseline  and  after  train- 
ing. Thirty-six  patients  completed  the  program 
and  constituted  the  study  group.  The  strength  of 
the  quadriceps  femoris  increased  significantly 
in  both  groups  (p  <  0.05),  but  the  improvement 
was  greater  in  the  AERO  +  ST  group  (20  ± 
1 2%  versus  8  ±  10%  [mean  ±  SD]  in  the  AERO 
group,  p  <  0.005).  The  thigh  MCSA  and  .strength 
of  the  pectoralis  major  muscle  increased  in  the 
AERO  -I-  ST  group  by  8  ±  13%  and  15  ±  9%, 


576 


Respiratory  Care  •  June  1 999  Vol  43  No  6 


respectively  (p  <  0.001),  but  not  in  the  AERO 
group  (3  ±  6%  and  2  ±  10%,  respectively,  p  > 
0.05).  These  changes  were  significantly  differ- 
ent in  the  two  study  groups  (p  <  0.01).  The 
increase  in  strength  of  the  latissimus  dorsi  mus- 
cle after  training  was  modest  and  of  similar 
magnitude  for  both  groups.  The  changes  in  peak 
exercise  work  rate,  6  MWD,  and  quality  of  life 
were  comparable  in  the  two  groups.  In  conclu- 
sion, the  addition  of  strength  training  to  aerobic 
training  in  patients  with  COPD  is  associated 
with  significantly  greater  increases  in  muscle 
strength  and  mass,  but  does  not  provide  addi- 
tional improvement  in  exercise  capacity  or  qual- 
ity of  life. 

Effect  of  Ventilator  Flow  Rate  on  Respira- 
tory Timing  in  Normal  Humans — Fernandez 
R,  Mendez  M.  Younes  M.  Am  J  Respir  Crit 
Care  Med  1999  Mar;159(3):710-7I9. 

Respiratory  rate  (RR)  increases  as  a  function  of 
ventilator  flow  rate  V.  We  wished  to  determine 
whether  this  is  due  to  a  decrease  in  neural  in- 
spiratory time  (Tin),  neural  expiratory  time 
(TEn),  or  both.  To  accomplish  this,  we  venti- 
lated 15  normal  subjects  in  the  assi.st.  volume 
cycled  mode.  Ventilator  flow  rate  was  varied  at 
random,  at  four  breaths  with  each  step,  over  the 
flow  range  from  0.8  (Vmin)  to  2.5  (Vmax)  L/s. 
Vy  was  kept  constant.  The  pressure  developed 
by  respiratory  muscles  (Pmus)  was  calculated 
with  the  equation  of  motion  (Pmus  =  V  •  R  + 

V  •  E  -  Paw.  where  V  =  flow.  R  =  resistance, 

V  =  volume.  E  =  elastance,  and  Paw  =  airway 
pressure).  Electromyography  of  the  diaphragm 
(Edi)  was  also  done  in  five  subjects.  Tin  and 
TEn  were  determined  from  the  Pmus  or  Edi 
waveform.  Tin  decreased  progressively  as  a 
function  of  V,  from  1 .44  ±  0.34  s  at  Vmin  to 
0.62  ±  0.26  s  at  Vmax  (p  <  0.00001).  Changes 
in  TEn  were  inconsistent  and  not  significant. 
TIn/Tlot  decreased  significantly  (0.30  ±  0.06 
at  Vmin  to  0. 1 8  ±  0.09  at  Vmax;  p  <  0.  0000 1 ). 
We  conclude  that  TI  is  highly  sensitive  to  ven- 
tilator now.  and  that  the  RR  response  to  V  is 
primarily  related  to  this  Tin  response.  Becau.se 
an  increase  in  V  progressively  reduces  Tln/Ttot, 
and  this  variable  is  an  important  determinant  of 
inspiratory  muscle  energetics,  we  further  con- 
clude that  inspiratory  muscle  energy  expendi- 
ture is  quite  sensitive  to  V  over  the  range  from 
0,8  to  2.5  L/s. 

Aspiration  of  Airway  Dead  Space.  A  New 
Method  To  Enhance  CO2  Elimination — De 

Robertis  E,  Sigurdsson  SE,  Drefeldt  B,  Jonson 
B.  Am  J  Respir  Crit  Care  Med  1 999  Mar;  1 59(3): 
728-732. 

Alveolar  ventilation  and  CO,  elimination  dur- 
ing mechanical  ventilation  can  be  enhanced  by 
reducing  dead-space  ventilation.  Aspiration  of 
gas  from  the  dead  space  (ASPIDS)  is  a  new 
principle,  according  to  which  gas  rich  in  CO, 


K    A 


SER        PERMANENTE 


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accolades  awarded  Kaiser  Permanente  by  joining  us  in  one  of  the 
following  positions: 

Respiratory  Care  Practitioners 

(Full-time,  Part-time  and  On-call ) 

For  opportunities  in  California,  please  call:  (800)  331-3976,  x3546. 

Northern  California:  Via  fax:  (800)  323-4886.  E-mail: 

recruitment@ncal.kaiperm.org,  reference  Source  Code:  0699RC. 

Southern  California:  Via  fax:  (888)  805-7562.  E-mail: 

kaiserjob-scal@kp.org,  reference  Source  Code:  0699RC. 

Pi, 

KAISER  PERMANEJVTTE 

California 

EEO/AA  •  www.kaiserpermaneme.org 


m 


Circle  115  on  reader  service  card 


during  late  expiration  is  aspirated  through  a 
channel  ending  at  the  distal  end  of  the  tracheal 
tube.  Simultaneously,  fresh  gas  injected  into  the 
inspiratory  line  fills  the  airway  down  to  the 
same  site.  We  hypothesized  that  ASPIDS  would 
allow  a  reduction  of  tidal  volume  (V^^)  and  air- 
way pressure  (Paw).  To  test  our  hypothesis  we 
studied  six  anaesthetized  and  mechanically  ven- 
tilated pigs  (24  ±  4  kg).  The  intention  was  to 
decrease  V^  while  keeping  P^^oj  constant  by 
using  ASPIDS.  V^  was  reduced  by  decreasing 
the  minute  ventilation  (V,;)  in  two  steps,  of  1.8 
L/min  (Vg  -  1.8)  and  2.2  L/niin  (Vj..  -  2.2), 
respectively,  and  by  increasing  respiratory  rate 
(RR)  from  20  to  46  breaths/min.  At  ASPIDS, 
peak  Paw  was  reduced  by  35%  at  V,;  -  1 .8  and 
at  Vg  -  2.2  (p  <  0.001),  and  by  20%  at  an  RR 
of  46  (p  <  0.01).  Paco,  W3s  maintained  or  re- 
duced at  ASPIDS.  No  intrinsic  positive  end- 
expiratory  pressure  developed.  Arterial  blood 
pressure  and  heart  rate  were  unaffected.  The 
results  show  that  ASPIDS  allows  a  reduction  in 
Vt  and  Paw  while  P^^cj,  is  kept  constant.  AS- 
PIDS does  not  lead  to  problems  associated  with 
jet  streams  of  gas  or  with  gas  humidification, 
and  can  be  developed  as  a  safe  technique. 


Efficacy  of  Tracheal  Gas  Insufflation  in  Spon- 
taneously Breathing  Sheep  with  Lung  Inju- 
ry—Cereda  MF,  Sparacino  ME,  Frank  AR,  Tra- 


woger  R,  Kolobow  T.  Am  J  Respir  Crit  Care 
Med  1999  Mar;159(3):845-850. 

Tracheal  gas  insufflation  (TGI)  decreases  dead 
space  (Vu)  and  can  be  combined  with  contin- 
uous positive  airway  pressure  (CPAP)  to  de- 
crease minute  volume  (Vp.)  and  effort  of  breath- 
ing. In  1 1  anesthetized  sheep,  we  induced  acute 
lung  injury  (ALI)  through  oleic  acid  (OA)  in- 
fusion and  studied  the  effects  of  TGI  combined 
with  CPAP  (CPAP-TGI)  at  different  TGI  flows 
and  with  catheters  of  different  designs.  Sheep 
were  randomized  to  two  groups:  Group  A  (n  = 
7)  was  placed  on  CPAP  and  CPAP-TGI  at  10 
and  15  L/min  of  insufflation  flow  delivered 
through  a  reverse  thrust  catheter  (RTC).  Group 
B  (n  =  4)  was  placed  on  CPAP  and  CPAP-TGI 
at  a  flow  of  10  L/min  delivered  through  a  RTC, 
and  through  a  straight  flow  catheter  (SEC).  Com- 
pared with  CPAP  alone,  CPAP-TGI  resulted  in 
significantly  lower  V,-,,  V5,;,  pressure  time  prod- 
uct, and  work  of  breathing.  We  found  no  addi- 
tional benefit  from  TGI  flow  of  15  L/min,  com- 
pared with  10  L/min,  and  no  statistically 
significant  difference  between  the  SEC  and  the 
RTC.  In  conclusion,  TGI  can  be  combined  with 
CPAP  in  this  model  of  ALI  to  reduce  ventila- 
tion and  effort  of  breathing. 

Sigh  in  Acute  Respiratory  Distress  Syn- 
drome— Pelosi  P,  Cadringher  P,  Bottino  N,  Pan- 


Respiratory  Care  •  June  1999  Vol  43  No  6 


577 


Abstracts 


igada  M,  Carrieri  F,  Riva  E,  et  al.  Am  J  Respir 
Crit  Care  Med  1999  Mar;159(3):872-880. 

Mechanical  ventilation  with  plateau  pressure 
lower  than  35  cm  HjO  and  high  positive  end- 
expiratory  pressure  (PEEP)  has  been  recom- 
mended as  lung  protective  strategy.  Ten  pa- 
tients with  ARDS  (five  from  pulmonary  [p]  and 
five  from  extrapulmonary  [exp]  origin),  under- 
went 2  h  of  lung  protective  strategy,  1  h  of  lung 
protective  strategy  with  three  consecutive  sighs/ 
min  at  45  cm  HjO  plateau  pressure,  and  1  h  of 
lung  protective  strategy.  Total  minute  ventila- 
tion, PEEP  (14.0  ±  2.2  cm  HjO),  inspiratory 
oxygen  fraction,  and  mean  airway  pressure  were 
kept  constant.  After  1  h  of  sigh  we  found  that: 
( 1 )  P^o,  increased  (from  92.8  ±  1 8.6  to  1 37.6  ± 
23.9  mm  Hg,  p  <  0.01),  venous  admixture  and 
Paco2  decreased  (from  38  ±  12  to  28  ±  14%, 
p  <  0.01;  and  from  52.7  ±  19.4to49.1  ±  18.4 
mm  Hg,  p  <  0.05,  respectively);  (2)  end-expi- 
ratory lung  volume  increased  (from  1.49  ±  0.58 
to  1.91  ±  0.67  L,  p  <  0.01),  and  was  signifi- 
cantly correlated  with  the  oxygenation  (r  =  0.82, 
p  <  0.01)  and  lung  elastance  (r  =  0.76,  p  < 
0.01)  improvement.  Sigh  was  more  effective  in 
ARDSexp  than  in  ARDSp.  After  1  h  of  sigh 
interruption,  all  the  physiologic  variables  re- 
turned to  baseline.  The  derecruitment  was  cor- 
related with  P„co,  (r  =  0.86,  p  <  0.01).  We 
conclude  that:  ( 1 )  lung  protective  strategy  alone 
at  the  PEEP  level  used  in  this  study  may  not 
provide  full  lung  recruitment  and  best  oxygen- 
ation; (2)  application  of  sigh  during  lung  pro- 
tective strategy  may  improve  recruitment  and 
oxygenation. 

Clinical  Use  of  Respiratory  Changes  in 
Arterial  Pulse  Pressure  To  Monitor  the 
Hemodynamic  Effects  of  PEEP— Michard  F, 
Chemla  D,  Richard  C,  Wysocki  M,  Pinsky  MR, 
Lecarpentier  Y,  Teboul  JL.  Am  J  Respir  Crit 
Care  Med  1999  Mar;159(3):935-939. 

In  ventilated  patients  with  acute  lung  injury 
(ALI)  we  investigated  whether  respiratory 
changes  in  arterial  pulse  pressure  (APP)  could 
be  related  to  the  effects  of  PEEP  and  fluid  load- 
ing (FL)  on  cardiac  index  (CI).  Measurements 
were  performed  before  and  after  application  of 
a  PEEP  (10  cm  HjO)  in  14  patients.  When  the 
PEEP-induced  decrease  in  CI  was  >  10%  (six 
patients),  measurements  were  also  performed 
after  FL.  Maximal  (PPmax)  and  minimal  (PP- 
min)  values  of  pulse  pressure  were  determined 
over  one  respiratory  cycle  and  APP  was  calcu- 
lated: APP  (%)  =  100  X  (PPmax  -  PPmin)/ 
([PPmax  -I-  PPmin]/2).  PEEP  decreased  CI  from 
4.2  ±  1.1  to  3.8  ±  1.3  L/min/m^  (p  <  0.01)  and 
increased  APP  from  9  ±  7  to  16  ±  13%  (p  < 
0.01).  The  PEEP-induced  changes  in  CI  corre- 
lated with  APP  on  ZEEP  (r  =  -0.91,  p  <  0.001) 
and  with  the  PEEP-induced  increase  in  APP  (r  = 
-0.79,  p  <  0.001).  FL  increa.sed  CI  from  3.5  ± 
1.1  to  4.2  ±  0.9  L/min/m^  (p  <  0.05)  and  de- 


creased APP  from  27  ±  13  to  14  ±  9%  (p  < 
0.05).  The  FL-induced  changes  in  CI  correlated 
with  APP  before  FL  (r  =  0.97,  p  <  0.01 )  and  with 
the  FL-induced  decrease  in  APP  (r  =  -0.85,  p  < 
0.05).  In  ventilated  patients  with  ALI,  APP  may 
be  useful  in  predicting  and  assessing  the  hemo- 
dynamic effects  of  PEEP  and  FL. 

A  Study  of  Twelve  Southern  California  Com- 
munities with  Differing  Levels  and  Types  of 
Air  Pollution.  I.  Prevalence  of  Respiratory 
Morbidity — Peters  JM,  Avol  E,  Navidi  W, 
London  SJ,  Gauderman  WJ,  Lurmann  F,  et  al. 
Am  J  Respir  Crit  Care  Med  1999  Mar;  1 59(3): 
760-767. 

To  study  possible  chronic  respiratory  effects  of 
air  pollutants,  we  initiated  a  10-yr  prospective 
cohort  study  of  Southern  California  children, 
with  a  study  design  focused  on  four  pollutants: 
ozone,  particulate  matter,  acids,  and  nitrogen 
dioxide  (NOj).  Twelve  demographically  simi- 
lar communities  were  selected  on  the  basis  of 
historic  monitoring  information  to  represent  ex- 
tremes of  exposure  to  one  or  more  pollutants. 
In  each  community,  about  150  public  school 
students  in  grade  4,  75  in  grade  7,  and  75  in 
grade  1 0  were  enrolled  through  their  classrooms. 
Informed  consent  and  written  responses  to  sur- 
veys about  students'  lifetime  residential  histo- 
ries, historic  and  current  health  status,  residen- 
tial characteristics,  and  physical  activity  were 
obtained  with  the  help  of  the  parents.  In  the  first 
testing  season,  3,676  students  returned  ques- 
tionnaires. We  confirmed  associations  previ- 
ously reported  between  respiratory  morbidity 
prevalence  and  the  presence  of  personal,  demo- 
graphic, and  residential  risk  factors.  Rates  of 
respiratory  illness  were  higher  for  males,  those 
living  in  houses  with  pets,  pests,  mildew,  and 
water  damage,  those  whose  parents  had  asthma, 
and  those  living  in  houses  with  smokers.  Wheeze 
prevalence  was  positively  associated  with  lev- 
els of  both  acid  (odds  ratio  [OR]  =  1.45;  95% 
confidence  interval  [CI],  1.14-1.83)  and  NOj 
(OR  =  1.54;  95%  CI,  1.08-2.19)  in  boys.  We 
conclude,  based  on  this  cross-sectional  assess- 
ment of  questionnaire  responses,  that  current 
levels  of  ambient  air  pollution  in  Southern  Cal- 
ifornia may  be  associated  with  effects  on  school- 
children's  respiratory  morbidity  as  assessed  by 
questionnaire. 

A  Study  of  Twelve  Southern  California  Com- 
munities with  Differing  Levels  and  Types  of 
Air  Pollution.  IL  Effects  on  Pulmonary  Func- 
tion— Peters  JM,  Avol  E,  Gauderman  WJ,  Linn 
WS,  Navidi  W,  London  SJ,  et  al.  Am  J  Respir 
Crit  Care  Med  1999  Mar;159(3):768-775. 

To  study  the  possible  chronic  respiratory  ef- 
fects of  air  pollutants,  we  designed  and  initiated 
a  10-yr  prospective  study  of  Southern  Califor- 
nia public  schoolchildren  living  in  12  commu- 
nities with  different  levels  and  profiles  of  air 


pollution.  The  design  of  the  study,  exposure 
assessment  methods,  and  survey  methods  and 
results  related  to  respiratory  symptoms  and  con- 
ditions are  described  in  the  accompanying  pa- 
per. Pulmonary  function  tests  were  completed 
on  3,293  subjects.  We  evaluated  cross-section- 
ally  the  effects  of  air  pollution  exposures  based 
on  data  collected  in  1 986-1990  by  existing  mon- 
itoring stations  and  data  collected  by  our  study 
team  in  1 994.  Expected  relationships  were  seen 
between  demographic,  physical,  and  other  en- 
vironmental factors  and  pulmonary  function  val- 
ues. When  the  data  were  stratified  by  sex,  an 
association  was  seen  between  pollution  levels 
and  lower  pulmonary  function  in  female  sub- 
jects, with  the  associations  being  stronger  for 
the  1994  exposure  data  than  the  1986-1990 
data.  After  adjustment,  PMIO,  PM2.5,  and  NOj 
were  each  significantly  associated  with  lower 
FVC,  FEV,,  and  maximal  midexpiratory  flow 
(MMEF);  acid  vapor  with  lower  FVC,  FEV,, 
peak  expiratory  flow  rate  (PEER),  and  MMEF; 
and  Oj  with  lower  PEFR  and  MMEF.  Effects 
were  generally  larger  in  those  girls  spending 
more  time  outdoors.  Stepwise  regression  of  ad- 
justed pulmonary  function  values  for  girls  in 
the  12  communities  showed  that  NO2  was  most 
strongly  associated  with  lower  FVC  (r  =  -0.74, 
p  <  0.01),  PM2.5  with  FEV,  (r  =  -0.72,  p  < 
0.01),  O3  with  PEFR  (r  =  -0.75,  p  <  0.005), 
and  PM2.5  with  MMEF  (r  =  -0.80,  p  <  0.005). 
There  was  a  statistically  significant  association 
between  ozone  exposure  and  decreased  FVC 
and  FEV  I  in  girls  with  asthma.  For  boys,  sig- 
nificant associations  were  seen  between  peak 
O3  exposures  and  lower  FVC  and  FEV,,  but 
only  in  those  spending  more  time  outdoors. 
These  findings  underiine  the  importance  of  fol- 
low-up of  this  cohort. 

Forced  Expiratory  Maneuvers  in  Very  Young 
Children:  Assessment  of  Flow  Limitation — 

Jones  MH,  Davis  SD,  Grant  D,  Christoph  K, 
Kisling  J,  Tepper  RS.  Am  J  Respir  Crit  Care 
Med  1999  Mar;159(3):791-795. 

The  application  of  negative  expiratory  pressure 
(NEP)  to  the  airway  opening  during  forced  ex- 
piratory maneuvers  has  recently  been  described 
as  a  noninvasive  method  to  assess  whether  flow 
limitation  is  achieved  in  adults.  This  method- 
ology has  great  potential  for  extending  the  mea- 
surement of  forced  expiratory  maneuvers  to 
young  children  who  may  not  produce  maximal 
efforts  as  reproducibly  as  adults.  We  used  NEP 
to  assess  flow  limitation  in  10  children  between 
3  and  5  yr  of  age.  NEP  was  well  tolerated  by  all 
subjects.  With  the  application  of  NEP,  there 
was  not  a  step  increase  in  flow,  a  finding  con- 
sistent with  flow  limitation  for  the  subjects.  In 
addition  to  visual  inspection,  we  proposed  a 
method  to  quantify  the  change  in  flow  during  a 
short  NEP.  The  flow-volume  curves  obtained 
with  and  without  NEP  were  visually  the  same, 
other  than  the  flow  transients  produced  by  NEP. 


578 


Respiratory  Care  •  June  1999  Vol  43  No  6 


Abstracts 


The  calculated  values  of  FVC  and  FEFjj.j,  were 
not  significantly  different  when  measured  from 
flow-  volume  curves  with  and  without  NEP. 
There  was  a  statistically  significant  increase  in 
FEV|  with  NEP;  however,  the  group  mean  in- 
crease in  FEV|  was  less  than  2%.  We  conclude 
that  NEP  may  be  a  useful  technique  to  deter- 
mine whether  flow  limitation  has  been  achieved 
in  young  children  performing  forced  expiratory 
maneuvers. 

Medication  Monitors  to  Treat  Tuberculosis: 
A  Supplement  to  Directly  Observed  Ther- 
apy. Moulding  TS.  Am  J  Respir  Crit  Care  Med 
1999  Mar;159(3):989-991. 

The  use  of  directly  observed  therapy  (DOT)  for 
nearly  all  cases  of  pulmonary  tuberculosis  (TB) 
is  being  widely  promoted  by  the  Centers  for 
Disease  Control,  but  its  implementation  is  be- 
ing resisted  by  many  health  professionals.  Con- 
sequently, less  than  half  of  the  patients  in  major 
metropolitan  health  departments  were  given 
DOT  in  1996.  The  usual  justification  for  "uni- 
versal" DOT  instead  of  selective  DOT  is  the 
well-known  difficulty  in  differentiating  between 
patients  who  are  reliable  in  taking  medication 
from  those  who  are  not.  Devices  called  medi- 
cation monitors,  which  record  when  medication 
is  removed  from  a  container,  were  shown  to  be 
effective  in  determining  the  reliability  of  TB 
patients  in  taking  medication  in  the  1960s  but 
were  cumbersome  to  use.  Since  then  several 
improved,  convenient  to  use,  electronic  medi- 
cation monitors  have  been  introduced  and  fur- 
ther improvements  can  be  anticipated.  These 
increasingly  practical  medication  monitors  need 
to  be  studied  as  a  supplement  to  DOT  in  order 
to  make  selective  DOT  an  effective  alternative 
to  "'universal"  DOT  in  managing  the  medica- 
tion compliance  problem  when  treating  TB. 

Arterial  Endothelial  Dysfunction  Related  to 
Passive  Smoking  Is  Potentially  Reversible  in 
Healthy  Young  Adults — Raitakari  OT,  Adams 
MR,  McCredie  RJ,  Griffiths  KA,  Celermajer 
DS.  Ann  Intern  Med  1999  Apr  6;130(7): 
578-581. 

BACKGROUND:  Passive  smoking  is  associ- 
ated with  early  arterial  damage,  but  the  poten- 
tial for  reversibility  of  this  damage  is  unknown. 
OBJECTIVE:  To  assess  the  reversibility  of  ar- 
terial endothelial  dysfunction,  a  key  marker  of 
early  atherosclerosis.  DESIGN:  Cross-sectional 
study.  SETTING:  Academic  medical  center. 
PARTICIPANTS:  60  healthy  persons  15  to  39 
years  of  age:  20  with  no  exposure  to  active  or 
passive  smoking,  20  nonsmoking  passive  smok- 
ers (exposure  to  environmental  tobacco  smoke 
for  a  1  hour  per  day  for  a  2  years),  and  20 
former  passive  smokers.  MEASUREMENTS: 
Arterial  endothelial  function  measured  by  non- 
invasive ultrasonography.  RESULTS:  Endothe- 
lium-dependent  dilatation  was  significantly  bet- 


ter in  former  passive  smokers  (5.1%  ±  4.1% 
[range,  -1.2%  to  15.6%])  than  in  current  pas- 
sive smokers  (2.3%  ±2.1%  [range,  -0.2%  to 
6.7%])  (p  =  0.01),  although  both  groups  were 
significantly  impaired  compared  with  nonsmok- 
ing controls  (8.9%  ±  3.2%  [range,  2.1%  to 
16.7%])  (p  s  0.01  for  both  comparisons).  CON- 
CLUSIONS: In  healthy  young  adults,  arterial 
endothelial  dysfunction  related  to  passive  smok- 
ing seems  to  be  partially  reversible. 

Acute  Heroin  Overdose — Sporer  KA.  Ann  In- 
tern Med  1999  Apr  6;130(7):584-590. 

Acute  heroin  overdose  is  a  common  daily  ex- 
perience in  the  urban  and  suburban  United  States 
and  accounts  for  many  preventable  deaths.  Her- 
oin acts  as  a  pro-drug  that  allows  rapid  and 
complete  central  nervous  system  absorption;  this 
accounts  for  the  drug's  euphoric  and  toxic  ef- 
fects. The  heroin  overdose  syndrome  (sensitiv- 
ity for  diagnosing  heroin  overdose,  92%;  spec- 
ificity, 76%)  consists  of  abnormal  mental  status, 
substantially  decreased  respiration,  and  miotic 
pupils.  The  response  of  naloxone  does  not  im- 
prove the  sensitivity  of  this  diagnosis.  Most 
overdoses  occur  at  home  in  the  company  of 
others  and  are  more  common  in  the  setting  of 
other  drugs.  Heroin-related  deaths  are  strongly 
associated  with  use  of  alcohol  or  other  drugs. 
Patients  with  clinically  significant  respiratory 
compromise  need  treatment,  which  includes  air- 
way management  and  intravenous  or  subcuta- 
neous naloxone.  Hospital  observation  for  sev- 
eral hours  is  necessary  for  recurrence  of 
hypoventilation  or  other  complications.  About 
3%  to  7%  of  treated  patients  require  hospital 
admission  for  pneumonia,  noncardiogenic 
pulmonary  edema,  or  other  complications. 
Methadone  maintenance  is  an  effective  preven- 
tive measure,  and  others  strategies  should  be 
studied. 

The  Assessment  of  Four  Different  Methods 
to  Verify  Tracheal  Tube  Placement  in  the 
Critical  Care  Setting — Knapp  S,  Kofler  J, 
Stoiser  B,  Thalhammer  F,  Burgmann  H,  Posch 
M,  et  al.  Anesth  Analg  1999  Apr;88(4): 
766-770. 

One  of  the  most  serious  complications  of  con- 
ventional endotracheal  intubation  is  unidenti- 
fied placement  of  the  tube  in  the  esophagus. 
The  aim  of  our  study  was  to  evaluate  four  dif- 
ferent methods  for  immediate  detection  of  the 
tube  position:  auscultation,  capnographic  deter- 
mination of  ETCO,,  esophageal  detection 
method  (EDM)  using  a  self-inflating  bulb,  and 
the  transillumination  method  using  a  lighted 
stylet  (Trachlight;  Laerdal,  Armonk,  NY).  Thir- 
ty-eight endotracheal  ly  intubated  patients  ad- 
mitted to  our  medical  intensive  care  unit  were 
enrolled  in  the  study.  A  second  identical  tube 
was  inserted  into  the  esophagus  under  laryngo- 
scopic  control.  The  endotracheal  tube  was  then 


disconnected  from  the  ventilator.  Two  blinded 
examiners,  one  experienced,  the  other  inexpe- 
rienced, determined  the  tube  position  within  30  s 
using  one  of  the  four  methods.  The  order  of  the 
tubes  tested  and  the  methods  used  were  ran- 
domized. In  130  of  152  examinations,  both  ex- 
aminers correctly  diagnosed  the  position  of  the 
tube.  The  wrong  result  was  obtained  by  both 
examiners  4  times;  only  the  experienced  exam- 
iner was  wrong  4  times,  and  only  the  inexpe- 
rienced examiner  was  wrong  14  times.  Using 
ETCO,,  both  examiners  were  correct  in  all  cases. 
Auscultation  showed  an  obvious  relation  to  the 
examiner's  experience:  the  experienced  exam- 
iner was  correct  in  all  cases,  the  inexperienced 
examiner  was  correct  in  only  68%  of  cases. 
Using  the  self-inflating  bulb,  there  were  two 
wrong  results  of  the  experienced  examiner  and 
one  wrong  result  of  the  inexperienced  exam- 
iner. The  transillumination  technique  was  as,so- 
ciated  with  a  high  error  rate  by  both  examiners 
(16%  and  13%,  respectively).  Comparing  all 
four  methods  showed  that  capnography  is  su- 
perior to  auscultation  (p  =  0.0005)  and  to  the 
Trachlight  detection  method  (p  =  0.0078).  EDM 
was  not  statistically  superior  to  auscultation  and 
transillumination.  Capnography  was  the  most 
reliable  method  for  rapid  evaluation  of  tube  po- 
sition, followed  by  EDM,  whereas  auscultation 
and  Trachlight  did  not  seem  to  be  of  compara- 
ble value.  Experience  was  a  determining  factor 
for  auscultation.  Implications:  To  prevent  un- 
identified esophageal  intubation,  a  serious  com- 
plication in  the  critical  care  setting,  four  meth- 
ods for  detecting  tube  position  were  tested  by 
two  examiners  (one  experienced,  the  other  in- 
experienced) in  endotracheally  intubated  pa- 
tients after  insertion  of  a  second  tube  into  the 
esophagus. 

Do  Laryngeal  Mask  Airway  Devices  Atten- 
uate Liquid  Flow  between  the  Esophagus  and 
Pharynx?  A  Randomized,  Controlled  Ca- 
daver Study — Keller  C,  Briniacombe  J,  Radler 
C,  Puhringer  F.  Anesth  Analg  1999  Apr;88(4): 
904-907. 

In  this  randomized,  controlled  cadaver  study, 
we  tested  the  hypothesis  that  the  standard  la- 
ryngeal mask  airway  (LMA)  and  flexible  laryn- 
geal mask  airway  (FLMA)  attenuate  liquid  tlow 
between  the  esophagus  and  pharynx.  Fifty  fresh 
cadavers  were  studied  in  four  LMA  groups.  Ten 
female  cadavers  had  a  size  4  LMA  and  10  had 
a  size  4  FLMA;  10  male  cadavers  had  a  size  5 
LMA  and  10  had  a  size  5  FLMA;  5  male  and  5 
female  cadavers  functioned  as  controls.  The 
chest  was  opened,  and  the  infusion  set  of  a 
pressure-controlled,  continuous  flow  pump  was 
inserted  into  the  esophagus  and  ligated  into 
place.  Esophageal  pressure  was  increased  in 
2-cm  H2O  increments.  Regurgitation  pressure 
was  the  esophageal  pressure  at  which  fluid  was 
first  seen  with  a  fiberoptic  scope  in  the  hypo- 
pharynx  (control  group)  and  above  the  cuff  or 


Respiratory  Care  •  June  1999  Vol  43  No  6 


579 


Abstracts 


within  the  bowl  (LMA  groups).  This  was  per- 
formed in  the  LMA  groups  at  0-40  mL  cuff 
volume  in  10-mL  increments.  Mean  (95%  con- 
fidence interval)  regurgitation  pressure  for  the 
control  group  was  7  (6-8)  cm  HjO  and  for  the 
LMA  groups  combined  was  19(1 7-20)  cm  HjO 
at  0  mL  cuff  volume.  47  (41-52)  cm  H,0  at  10 
mL,  51  (44-55)  cm  H,0  at  20  mL,  52  (45-56) 
cm  H,0  at  30  mL,  and  52  (45-55)  cm  H,0  at 
40  mL.  The  increase  in  regurgitation  pressure 
with  increasing  cuff  volume  from  0  to  10  mL 
was  statistically  significant  (p  <  0.0001).  Re- 
gurgitation pressure  was  higher  for  the  LMA 
groups  at  all  cuff  volumes  compared  with  the 
control  group  (p  <  0.0001 ).  There  were  no  dif- 
ferences in  regurgitation  pressure  among  the 
LMA  groups.  We  conclude  that  the  correctly 
placed  LMA  and  FLMA  attenuate  liquid  flow 
between  the  esophagus  and  pharynx.  Implica- 
tions: We  have  shown,  in  cadavers,  that  the 
correctly  placed  standard  and  flexible  laryngeal 
mask  airways  attenuate  liquid  flow  between  the 
pharynx  and  esophagus. 

Early  Inhaled  Glucocorticoid  Therapy  to  Pre- 
vent Bronchopulmonary  Dysplasia — Cole 
CH.  Colton  T.  Shah  BL,  Abbasi  S.  MacKinnon 
BL,  Demissie  S,  Frantz  ID  y.  N  Engl  J  Med 
1999  Apr  1;340(  13):  1005-1010. 

BACKGROUND:  The  safety  and  efficacy  of 
inhaled  glucocorticoid  therapy  for  asthma  stim- 
ulated its  use  in  infants  to  prevent  bronchopul- 
monary dysplasia.  We  tested  the  hypothesis  that 
early  therapy  with  inhaled  glucocorticoids 
would  decrease  the  frequency  of  bronchopul- 
monary dysplasia  in  premature  infants.  METH- 
ODS: We  conducted  a  randomized,  multicenter 
trial  of  inhaled  beclomethasone  or  placebo  in 
253  infants.  3  to  14  days  old,  bom  before  33 
weeks  of  gestation  and  weighing  1 250  g  or  less 
at  birth,  who  required  ventilation  therapy.  Be- 
clomethasone was  delivered  in  a  decreasing  dos- 
age, from  40  to  5  microg  per  kilogram  of  body 
weight  per  day,  for  four  weeks.  The  primary 
outcome  measure  was  bronchopulmonary  dys- 
plasia at  28  days  of  age.  Secondary  outcomes 
included  bronchopulmonary  dysplasia  at  36 
weeks  of  postmenstrual  age,  the  need  for  sys- 
temic glucocorticoid  therapy,  the  need  for  bron- 
chodilator  therapy,  the  duration  of  respiratory 
support,  and  death.  RESULTS:  One  hundred 
twenty-three  infants  received  beclomethasone. 
and  1.30  received  placebo.  The  frequency  of 
bronchopulmonary  dysplasia  was  similar  in  the 
two  groups:  43  percent  in  the  beclomethasone 
group  and  45  percent  in  the  placebo  group  at  28 
days  of  age,  and  1 8  percent  in  the  beclometha- 
sone group  and  20  percent  in  the  placebo  group 
at  36  weeks  of  postmenstrual  age.  At  28  days  of 
age.  fewer  infants  in  the  beclomethasone  group 
than  in  the  placebo  group  were  receiving 
.systemic  glucocorticoid  therapy  (relative  risk, 
0.6;  95  percent  confidence  interval.  0.4  to  1 .0) 
and  mechanical  ventilation  (relative  risk,  0.8: 


95  percent  confidence  interval,  0.6  to  1 .0).  CON- 
CLUSIONS: Early  beclomethasone  therapy  did 
not  prevent  bronchopulmonary  dysplasia  but 
was  associated  with  lower  rates  of  use  of  sys- 
temic glucocorticoid  therapy  and  mechanical 
ventilation. 


Factors  that  Predict  Preexisting  Colonization 
with  Antibiotic-Resistant  Gram-Negative  Ba- 
cilli in  Patients  Admitted  to  a  Pediatric  In- 
tensive Care  Unit — Toltzis  P,  Hoyen  C,  Spin- 
ner-Block S,  Salvator  AE,  Rice  LB.  Pediatrics 
1999  Apr;103(4  Pt  l):719-723. 

OBJECTIVE:  To  predict  which  patients  hospi- 
talized in  a  pediatric  intensive  care  unit  (ICU) 
are  colonized  with  antibiotic-resistant  gram- 
negative  rods  on  admission.  METHODS:  Con- 
secutive children  admitted  to  a  pediatric  ICU 
over  a  6-month  period  were  entered  into  the 
study.  A  questionnaire  soliciting  information  re- 
garding the  child's  medical  history  and  home 
environment  was  completed  by  the  parent  or 
guardian.  Nasopharyngeal  and  rectal  cultures 
were  obtained  on  each  of  the  first  3  days  of  ICU 
admission,  and  organisms  resistant  to  ceftazi- 
dime or  tobramycin  were  identified.  Only 
clonally  distinct  organisms,  as  confirmed  by 
pulsed  field  gel  electrophoresis,  were  analyzed. 
The  association  between  identification  of  colo- 
nization with  an  antibiotic-resistant  gram-neg- 
ative rod  within  3  days  of  ICU  admission  and 
factors  included  in  the  questionnaire  was  tested 
by  r  or  /  test.  RESULTS.  In  64  (8.8%)  of  727 
admissions,  an  antibiotic-resistant  gram-nega- 
tive bacillus  was  isolated  within  the  first  3  ICU 
days.  More  than  half  were  identified  on  the  day 
of  admission.  Colonization  was  a.ssociated  with 
two  factors  related  to  the  patient's  medical  his- 
tory, namely,  number  of  past  ICU  admissions 
(1.98  vs  0.87)  and  administration  of  intrave- 
nous antibiotics  within  the  past  12  months 
(67.9%  vs  28.2%).  No  association  was  found 
between  colonization  and  exposure  to  oral  an- 
tibiotics. In  addition,  factors  related  to  the  child's 
environment  were  also  associated  with  pre- 
sumed importation  of  an  antibiotic-resistant 
gram-negative  rod  into  the  ICU.  Specifically, 
residence  in  a  chronic  care  facility  was  strongly 
associated  with  colonization  (28.3%  vs  2.6%); 
exposure  to  a  household  contact  who  had  been 
hospitalized  in  the  past  12  months  also  pre- 
dicted colonization  (41.7%  vs  18.5%).  CON- 
CLUSIONS: These  data  suggest  that  a  profile 
can  be  established  characterizing  children  col- 
onized with  resistant  gram-negative  bacilli  be- 
fore admission  to  a  pediatric  ICU.  Infection  con- 
trol measures  may  help  to  contain  these 
potentially  dangerous  bacteria  once  they  have 
been  introduced  into  the  unit. 


Ipratropium  Bromide  Added  to  Asthma 
Treatment  in  the  Pediatric  Emergency  De- 
partment— Zorc  JJ,  Pusic  MV,  Ogbom  CJ,  Le- 


bet  R,  Duggan  AK.  Pediatrics  1999  Apr,103(4 
Pt  l):748-752. 

OBJECTIVE:  To  determine  if  the  addition  of 
ipratropium  bromide  to  the  emergency  depart- 
ment (ED)  treatment  of  childhood  asthma  re- 
duces lime  to  discharge,  number  of  nebulizer 
treatments  before  discharge,  and  the  rate  of  hos- 
pitalization. METHODS:  Patients  >12  months 
of  age  were  eligible  if  they  were  to  be  treated 
according  to  a  standardized  ED  protocol  for 
acute  asthma  with  nebulized  albuterol  (2.5  mg/ 
dose  if  weight  <30  kg,  otherwise  5  mg/dose) 
and  oral  prednisone  or  prednisolone  (2  mg/kg 
up  to  80  mg).  Subjects  were  randomized  to  re- 
ceive either  ipratropium  (250  microg/dose)  or 
normal  saline  ( I  mL/dose)  with  each  of  the  first 
three  nebulized  albuterol  doses.  Further  treat- 
ment after  the  first  hour  was  determined  by 
physicians  blinded  to  subject  group  assignment. 
Records  were  reviewed  to  determine  the  length 
of  time  to  discharge  home  from  the  ED,  num- 
ber of  doses  of  albuterol  given  before  discharge, 
and  the  number  of  patients  admitted  to  the  hos- 
pital. RESULTS:  Four  hundred  twenty-seven 
patients  were  randomized  to  ipratropium  or  con- 
trol groups;  these  groups  were  similar  in  all 
baseline  measures.  Among  patients  discharged 
from  the  ED,  ipratropium  group  subjects  had 
13%  shorter  treatment  time  (mean,  185  min- 
utes, vs  control,  213  minutes)  and  fewer  total 
albuterol  do.ses  (median,  three,  vs  control,  four). 
Admission  rates  did  not  differ  significantly 
(18%,  vs  control,  22%).  CONCLUSIONS:  The 
addition  of  three  doses  of  ipratropium  to  an  ED 
treatment  protocol  for  acute  asthma  was  asso- 
ciated with  reductions  in  duration  and  amount 
of  treatment  before  discharge. 

Day  Care  Centers  and  Respiratory  Health — 

Nafstad  P,  Hagen  JA,  Oie  L.  Magnus  P,  Jaakkola 
JJ.  Pediatrics  1999  Apr;103(4  Pt  l):753-758. 

OBJECTIVE:  To  estimate  the  effects  of  the  type 
of  day  care  on  respiratory  health  in  preschool 
children.  METHODS:  A  population-based 
cross-sectional  study  of  Oslo  children  born  in 
1992  was  conducted  at  the  end  of  1996.  A  self- 
administered  questionnaire  inquired  about  day 
care  arrangements,  children's  health,  environ- 
mental conditions,  and  family  characteristics 
(n  =  3853;  response  rate,  79%).  RESULTS:  In 
logistic  regression  controlling  for  confounding, 
children  in  day  care  centers  had  more  often 
nightly  cough  (adjusted  odds  ratio,  1.89;  95% 
confidence  interval,  1.34-2.  67),  and  blocked 
or  runny  nose  without  common  cold  ( 1 .55;  1 .07- 
1.61)  during  the  past  12  months  compared  with 
children  in  home  care.  Poisson  regression  anal- 
ysis showed  an  increased  risk  of  the  common 
cold  (incidence  rate  ratio,  1.21;  1.12-1.30)  and 
otitis  media  (1.48;  1.22-1.80),  and  the  attribut- 
able proportion  was  17.4%  (95%  confidence 
interval,  10.7-23.1)  for  the  common  cold  and 
32.4%  ( 1 8. 0-44.4)  for  otitis  media.  Early  start- 


580 


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ing  age  in  the  day  care  center  increased  the  risk 
of  developing  recurrent  otitis  media.  Also  the 
lifetime  risk  of  doctor-diagnosed  asthma  was 
higher  in  children  who  started  day  care  center 
attendance  during  the  first  2  years  of  life.  CON- 
CLUSIONS: Attendance  to  day  care  centers  in- 
creases the  risk  of  upper  respiratory  symptoms 
and  infections  in  3-  to  5-year-old  children.  The 
starting  age  seems  to  be  an  important  determi- 
nant of  recurrent  otitis  media  as  well  as  asthma. 
The  effect  of  day  care  center  attendance  on 
asthma  is  limited  to  age  up  to  2  years.  This 
effect  is  most  likely  mediated  via  early  respi- 
ratory tract  infections  that  are  substantially  more 
common  in  children  in  day  care  centers  com- 
pared with  children  in  home  care. 


Morbidity  from  Astlima  in  Relation  to  Reg- 
ular   Treatment:     A    Community    Based 

Study— Walsh  LJ,  Wong  CA,  Cooper  S,  Gu- 
han  AR,  Pringle  M,  Tattersfield  AE.  Thorax 
1999  Apr;54(4):296-300. 

BACKGROUND:  The  extent  to  which  asthma 
morbidity  in  the  community  occurs  in  patients 
who  are  having  relatively  little  treatment  or  in 
those  on  step  3  or  above  of  the  British  asthma 
management  guidelines  is  uncertain.  We  have 
looked  at  this  in  a  community  population  in 
southern  Nottinghamshire.  METHODS:  A  cross 
sectional  review  of  treatment  in  all  patients  over 
the  age  of  four  with  diagnosed  asthma  was  car- 


ried out  in  five  large  general  practices  (popu- 
lation 38  865)  in  1995/6  using  computerised 
general  practice  records.  The  patients'  usual 
treatment  was  obtained  from  prescription  data 
and  categorised  by  the  appropriate  step  on  the 
British  guidelines  on  asthma  management.  Two 
measures  of  morbidity,  the  request  for  10  or 
more  short  acting  beta  agonist  inhalers  a  year  or 
the  need  for  a  course  of  oral  corticosteroids  in 
the  last  year,  were  related  to  the  regular  treat- 
ment of  the  patients.  RESULTS:  Of  the  3373 
patients  (8.7%)  given  a  diagnosis  of  a.sthma.  the 
percentage  on  steps  1,  2,  3,  4,  and  5  of  treat- 
ment were  54%,  22%,  11%,  3.6%,  and  1%, 
respectively,  with  a  further  8%  having  had  no 
treatment.  During  the  past  year  13.6%  had  been 
prescribed  10  or  more  beta  agonist  inhalers  and 
12.5%  had  received  at  least  one  course  of  oral 
corticosteroids.  Both  measures  occurred  more 
frequently  in  patients  taking  more  prophylactic 
treatment  (step  3  or  above).  Nevertheless,  be- 
cause most  patients  were  on  steps  1  and  2  of  the 
treatment  guidelines,  more  than  half  the  patients 
requiring  high  doses  of  inhaled  beta  agonists  or 
a  course  of  oral  prednisolone  came  from  those 
taking  low  dose  or  no  regular  inhaled  cortico- 
steroid. CONCLUSIONS:  Evidence  of  morbid- 
ity from  asthma  was  found  in  many  patients 
taking  little  or  no  prophylactic  medication  and 
this  should  be  amenable  to  improved  education. 
A  different  approach  may  be  needed  for  pa- 
tients with  continuing  morbidity  who  are  al- 


ready taking  higher  doses  of  prophylactic  med- 
ication. 


Risk  Factors  for  Death  from  Asthma,  Chronic 
Obstructive  Pulmonary  Disease,  and  Cardio- 
vascular Disease  after  a  Hospital  Admission 
for  Asthma — Guite  HF.  Dundas  R,  Burney  PG. 
Thorax  1999  Apr:54(4):301-307. 

BACKGROUND:  Patients  with  asthma  have  an 
increased  risk  of  death  from  causes  other  than 
asthma.  A  study  was  undertaken  to  identify 
whether  severity  of  asthma,  its  treatment,  or 
associated  co-morbidity  were  associated  with 
increased  risk  of  death  from  other  causes. 
METHODS:  Eighty  five  deaths  from  all  causes 
occurring  within  three  years  of  discharge  from 
hospital  in  a  cohort  of  2242  subjects  aged  16-64 
years  admitted  for  asthma  were  compared  with 
a  random  sample  of  61  controls  aged  <45  years 
and  6 1  aged  >  45  years  from  the  same  cohort. 
RESULTS:  Deaths  from  asthma  were  associ- 
ated with  a  history  of  clinically  severe  asthma 
(OR  6.29  (95%  CI  1.84  to  21.52)),  chest  pain 
(OR  3.78  (95%  CI  1.06  to  13.5)),  biochemical 
or  haematological  abnormalities  at  admission 
(OR  4.12  (95%  CI  1.36  to  12.49)),  prescription 
of  ipratropium  bromide  (OR  4.04  (95%  CI  1.47 
to  1 1.13)),  and  failure  to  prescribe  inhaled  ste- 
roids on  discharge  (OR  3.45  (95%  CI  1.35  to 
9.10)).  Deaths  from  chronic  obstructive  pulmo- 
nary disease  (COPD)  were  associated  with  lower 


Respiratory  Care  •  June  1999  Vol  43  No  6 


581 


Abstracts 


peak  expiratory  How  rates  (OR  2.56  (95%  CI 
1.52  to  4.35)  for  each  50  1/min  change),  a  his- 
tory of  smoking  (OR  5.03  (95%  CI  1.17  to 
21.58)),  prescription  of  ipratropium  bromide 
(OR  7.75  (95%  CI  2.21  to  27.14)),  and  failure 
to  prescribe  inhaled  steroids  on  discharge  (OR 
3.33  (95%  CI  0.95  to  11.10)).  Cardiovascular 
deaths  were  more  common  among  those  pre- 
scribed ipratropium  bromide  on  discharge  (OR 
3.55  (95%  CI  1.05  to  1 1.94))  and  less  likely  in 
those  admitted  after  an  upper  respiratory  tract 
infection  (OR  0.2 1  (95%  CI  0.05  to  0.95)).  Treat- 
ment with  ipratropium  bromide  at  discharge  was 
associated  with  an  increased  risk  of  death  from 
asthma  even  after  adjusting  for  peak  flow,  COPD 
and  cardiovascular  co-morbidity,  ever  having 
smoked,  and  age  at  onset  of  asthma.  CONCLU- 
SIONS: Prescription  of  inhaled  steroids  on  dis- 
charge is  important  even  for  those  patients  with 
co-existent  COPD  and  asthma.  Treatment  with 
ipratropium  at  discharge  is  as.sociated  with  in- 
creased risk  of  death  from  asthma  even  after 
adjustment  for  a  range  of  markers  of  COPD. 
These  results  need  to  be  tested  in  larger  studies. 

Comparison  of  Two  New  Methods  for  the 
Measurement  of  Lung  Volumes  with  Two 
Standard  Methods— Cliff  IJ,  Evans  AH,  Pan- 
tin  CF,  Baldwin  DR.  Thorax  1999  Apr;54(4): 
329-333. 

BACKGROUND:  The  two  most  commonly 
used  methods  for  the  measurement  of  lung  vol- 
umes are  helium  dilution  and  body  plethysmog- 
raphy. Two  methods  have  been  developed  which 
are  both  easier  and  less  time  consuming  to  per- 
form. Mathematical  modeling  uses  complex  cal- 
culations from  the  flow-volume  loop  to  derive 
total  lung  capacity  (TLC),  and  the  nitrogen  bal- 
ance technique  uses  nitrogen  from  the  atmo- 
sphere to  calculate  lung  volume  in  a  similar 
way  to  helium  dilution.  This  study  was  designed 
to  compare  the  two  new  methods  with  the  two 
standard  methods.  METHODS:  Sixty  one  sub- 
jects were  studied,  23  with  normal  lung  func- 
tion, 17  with  restrictive  airway  disease,  and  21 
with  obstructive  ventilatory  defects.  Each  sub- 
ject underwent  repeated  measurements  of  TLC 
by  each  of  the  four  methods  in  random  order. 
Reproducible  values  were  obtained  for  each 
method  according  to  BTS/ARTP  guidelines. 
Bland-Altman  plots  were  constructed  for  com- 
parisons between  the  methods  and  paired  t  tests 
were  used  to  assess  differences  in  means.  RE- 
SULTS: Bland-Altman  plots  showed  that  the 
differences  between  body  plethysmography  and 
helium  dilution  fell  into  clinically  acceptable 
ranges  (agreement  limits  ±  0.9  1).  The  agree- 
ment between  mathematical  modeling  or  the 
nitrogen  balance  technique  and  helium  dilution 
or  body  plethysmography  was  poor  (±  1.8-3.4 
1),  especially  for  subjects  with  airflow  obstruc- 
tion. CONCLUSIONS:  Neither  of  the  new  meth- 
ods agrees  sufficiently  with  standard  methods 
to  be  useful  in  a  clinical  setting. 


Pseudo-Steroid  Resistant  Asthma — Thomas 
PS,  Geddes  DM,  Barnes  PJ.  Thorax  1999  Apr; 
54(4):352-356. 

BACKGROUND:  Steroid  resistant  asthma 
(SRA)  represents  a  small  subgroup  of  those  pa- 
tients who  have  asthma  and  who  are  difficult  to 
manage.  Two  patients  with  apparent  SRA  are 
described,  and  12  additional  cases  who  were 
admitted  to  the  same  hospital  are  reviewed. 
METHODS:  The  subjects  were  selected  from  a 
tertiary  hospital  setting  by  review  of  all  asthma 
patients  admitted  over  a  two  year  period.  Sub- 
jects were  defined  as  those  who  failed  to  re- 
spond to  high  doses  of  bronchodilators  and  oral 
glucocorticosteroids,  as  judged  by  subjective  as- 
sessment, audible  wheeze  on  examination,  and 
serial  peak  flow  measurements.  RESULTS:  In 
11  of  the  14  patients  identified  there  was  little 
to  substantiate  the  diagnosis  of  severe  or  steroid 
resistant  asthma  apart  from  symptoms  and  up- 
per respiratory  wheeze.  Useful  tests  to  differ- 
entiate this  group  of  patients  from  those  with 
severe  asthma  appear  to  be:  the  inability  to  per- 
form reproducible  forced  expiratory  manoeu- 
vres, normal  airway  resistance,  and  a  concen- 
tration of  histamine  causing  a  20%  fall  in  the 
forced  expiratory  volume  (FEV,)  being  within 
the  range  for  normal  subjects  (PC^o).  Of  the  14 
subjects,  four  were  health  care  staff  and  two 
reported  childhood  sexual  abuse.  CONCLU- 
SION: Such  patients  are  important  to  identify 
as  they  require  supportive  treatment  which 
should  not  consist  of  high  doses  of  glucocorti- 
costeroids and  beta-2  adrenergic  agonists.  Di- 
agnoses other  than  asthma,  such  as  gastro-oe- 
sophageal  reflux,  hyperventilation,  vocal  cord 
dysfunction  and  sleep  apnoea,  should  be  sought 
as  these  may  be  a  cause  of  glucocorticosteroid 
treatment  failure  and  pseudo-SRA,  and  may  re- 
spond to  alternative  treatment. 

Summary  of  Effects  of  Parental  Smoking  on 
the  Respiratory  Health  of  Children  and  Im- 
plications for  Research — Cook  DG,  Strachan 
DP.  Thorax  1999  Apr;54(4):357-366. 

BACKGROUND:  Two  recent  reviews  have  as- 
sessed the  effect  of  parental  smoking  on  respi- 
ratory disease  in  children.  METHODS:  The  re- 
sults of  the  systematic  quantitative  review 
published  as  a  series  in  Thorax  are  summarised 
and  brought  up  to  date  by  considering  papers 
appearing  on  EMBASE  or  Medline  up  to  June 
1998.  The  findings  are  compared  with  those  of 
the  review  published  recently  by  the  Califor- 
nian  Environmental  Protection  Agency  (EPA). 
Areas  requiring  further  research  are  identified. 
RESULTS:  Overall  there  is  a  very  consistent 
picture  with  odds  ratios  for  respiratory  illnesses 
and  symptoms  and  middle  ear  disease  of  be- 
tween 1 .2  and  1 .6  for  either  parent  smoking,  the 
odds  usually  being  higher  in  pre-school  than  in 
school  aged  children.  For  sudden  infant  death 
syndrome  the  odds  ratio  for  maternal  smoking 


is  about  2.  Significant  effects  from  paternal 
smoking  suggest  a  role  for  postnatal  exposure 
to  environmental  tobacco  smoke.  Recent  pub- 
lications do  not  lead  us  to  alter  the  conclusions 
of  our  earlier  reviews.  While  essentially  narra- 
tive rather  than  systematic  and  quantitative,  the 
findings  of  the  Californian  EPA  review  are 
broadly  similar.  In  addition  they  have  reviewed 
studies  of  the  effects  of  environmental  tobacco 
smoke  on  children  with  cystic  fibrosis  and  con- 
clude from  the  limited  evidence  that  there  is  a 
strong  case  for  a  relationship  between  parental 
smoking  and  admissions  to  hospital.  They  also 
review  data  from  adults  of  the  effects  of  acute 
exposure  to  environmental  tobacco  smoke  un- 
der laboratory  conditions  which  suggest  acute 
effects  on  spirometric  parameters  rather  than  on 
bronchial  hyperresponsiveness.  It  seems  likely 
that  such  effects  are  also  present  in  children. 
CONCLUSIONS:  Substantial  benefits  to  chil- 
dren would  arise  if  parents  stopped  smoking 
after  birth,  even  if  the  mother  smoked  during 
pregnancy.  Policies  need  to  be  developed  which 
reduce  smoking  amongst  parents  and  protect 
infants  and  young  children  from  exposure  to 
environmental  tobacco  smoke.  The  weight  of 
evidence  is  such  that  new  prevalence  studies 
are  no  longer  justified.  What  are  needed  are 
studies  which  allow  comparison  of  the  effects 
of  critical  periods  of  exposure  to  cigarette 
smoke,  particularly  in  utero,  early  infancy,  and 
later  childhood.  Where  longitudinal  studies  are 
carried  out  they  should  be  analysed  to  look  at 
the  way  in  which  changes  in  exposure  are  re- 
lated to  changes  in  outcome.  Better  still  would 
be  studies  demonstrating  reversibility  of  adverse 
effects,  especially  in  asthmatic  subjects  or  chil- 
dren with  cystic  fibrosis. 

Cardiopulmonary  Resuscitation:  Effect  of 
CPAP  on  Gas  Exchange  during  Chest  Com- 
pressions— Hevesi  ZG,  Thrush  DN,  Downs  JB, 
Smith  RA.  Anesthesiology  1999  Apr;90(4): 
1078-1083. 

BACKGROUND:  Conventional  cardiopulmo- 
nary resuscitation  (CPR)  includes  80-IOO/min 
precordial  compressions  with  intermittent  pos- 
itive pressure  ventilation  (IPPV)  after  every  fifth 
compression.  To  prevent  gastric  insufflation, 
chest  compressions  are  held  during  IPPV  if  the 
patient  is  not  intubated.  Elimination  of  IPPV 
would  simplify  CPR  and  might  offer  physio- 
logic advantages,  but  compression-induced  ven- 
tilation without  IPPV  has  been  shown  to  result 
in  hypercapnia.  The  authors  hypothesized  that 
application  of  continuous  positive  airway  pres- 
sure (CPAP)  might  increase  CO2  elimination 
during  chest  compressions.  METHODS:  After 
appropriate  instrumentation  and  measurement 
of  baseline  data,  ventricular  fibrillation  was  in- 
duced in  18  pigs.  Conventional  CPR  was  per- 
formed as  a  control  (CPR(C))  for  5  min.  Pauses 
were  then  discontinued,  and  animals  were  as- 
signed randomly  to  receive  alternate  trials  of 


582 


Respiratory  Care  •  June  1 999  Vol  43  No  6 


Abstracts 


uninterrupted  chest  compressions  at  a  rate  of 
8()/min  without  IPPV,  either  at  atmospheric  air- 
way pressure  (CPR(ATM))  or  with  CPAP 
(CPR(CPAP)).  CPAP  was  adjusted  to  produce 
a  minute  ventilation  of  75%  of  the  animal's 
baseline  ventilation.  Data  were  summarized  as 
mean  ±  SD  and  compared  with  Student  t  test 
for  paired  observations.  RESULTS:  During  CPR 
without  IPPV,  CPAP  decreased  P„co,  (55±28 
vs.  100±16  mmHg)  and  increased  S„o, 
(0.86±0.19  vs.  0.50±0.18%;p<  0.001).  CPAP 
also  increased  arteriovenous  oxygen  content  dif- 
ference (10.7±3.1  vs.  5.5±2.3  mL/dl  blood) 
and  CO,  elimination  (120±20  vs.  12±20  niL/ 
min;  p  <  0.01).  Differences  between  CPR(C- 
PAP)  and  CPR(ATM)  in  aortic  blood  pressure, 
cardiac  output,  and  stroke  volume  were  not  sig- 
nificant. CONCLUSIONS:  Mechanical  ventila- 
tion may  not  be  necessary  during  CPR  as  long 
as  CPAP  is  applied.  Discontinuation  of  IPPV 
will  simplify  CPR  and  may  offer  physiologic 
advantage. 

Efficacy  of  Salmeterol  Xinafoate  in  the  Treat- 
ment of  COPD— Mahler  DA,  Donohue  JF,  Bar- 
bee  RA,  Goldman  MD,  Gross  NJ,  Wisniewski 
ME,  et  al.  Chest  1999;115(4); 
957-965. 

Study  objectives:  To  examine  and  compare  the 
efficacy  and  safety  of  salmetero!  xinafoate,  a 
long-acting  p2-adrenergic  agonist,  with  inhaled 
ipratropium  bromide  and  inhaled  placebo  in  pa- 
tients with  COPD.  Design:  A  stratified,  ran- 
domized, double-blind,  double-dummy,  place- 
bo-controlled, parallel  group  clinical  trial. 
Setting:  Multiple  sites  at  clinics  and  university 
medical  centers  throughout  the  United  States. 
Patients:  Four  hundred  eleven  symptomatic  pa- 
tients with  COPD  with  FEV,  s  65%  predicted 
and  no  clinically  significant  concurrent  disease. 
Interventions:  Comparison  of  inhaled  salmet- 
erol (42  fxg  twice  daily),  inhaled  ipratropium 
bromide  (36  (xg  four  times  a  day),  and  inhaled 
placebo  (2  puffs  four  times  a  day)  over  1 2  weeks. 
Results:  Salmeterol  xinafoate  was  significantly 
(p  <  0.0001)  better  than  placebo  and  ipratro- 
pium in  improving  lung  function  at  the  recom- 
mended doses  over  the  12- week  trial.  Both  sal- 
meterol and  ipratropium  reduced  dyspnea 
related  to  activities  of  daily  living  compared 
with  placebo:  this  improvement  was  associated 
with  reduced  use  of  supplemental  albuterol. 
Analyses  of  time  to  first  COPD  exacerbation 
revealed  salmeterol  to  be  superior  to  placebo 
and  ipratropium  (p  <  0.05).  Adverse  effects 
were  similar  among  the  three  treatments.  Con- 
clusions: These  collective  data  support  the  use 
of  salmeterol  as  first-line  bronchodilator  ther- 
apy for  the  long-term  treatment  of  airflow  ob- 
struction in  patients  with  COPD. 

Publislied  Criteria  for  Evaluating  Health  Re- 
lated Web  Sites:  Review— Kim  P,  Eng  TR, 


Deering  MJ,  Maxfield  A,  BMJ  1999;318 
(7184):647. 

Objective:  To  review  published  criteria  for  spe- 
cifically evaluating  health  related  information 
on  the  world  wide  web,  and  to  identify  areas  of 
consensus.  Design:  Search  of  world  wide  web 
sites  and  peer  reviewed  medical  journals  for 
explicit  criteria  for  evaluating  health  related  in- 
formation on  the  web,  using  Medline  and  Lexis- 
Nexis  databases,  and  the  following  internet 
search  engines:  Yahoo!,  Excite,  Altavista,  We- 
bcrawler,  HotBot,  Infoseek,  Magellan  Internet 
Guide,  and  Lycos.  Criteria  were  extracted  and 
grouped  into  categories.  Results:  29  published 
rating  tools  and  journal  articles  were  identified 
that  had  explicit  criteria  for  assessing  health 
related  web  sites.  Of  the  165  criteria  extracted 
from  these  tools  and  articles,  132  (80%)  were 
grouped  under  one  of  1 2  specific  categories  and 
33  (20%)  were  grouped  as  miscellaneous  be- 
cause they  lacked  specificity  or  were  unique. 
The  most  frequently  cited  criteria  were  those 
dealing  with  content,  design  and  aesthetics  of 
site,  disclosure  of  authors,  sponsors,  or  devel- 
opers, currency  of  information  (includes  fre- 
quency of  update,  freshness,  maintenance  of 
site),  authority  of  source,  ease  of  use,  and  ac- 
cessibility and  availability.  Conclusions:  Results 
suggest  that  many  authors  agree  on  key  criteria 
for  evaluating  health  related  web  sites,  and  that 
efforts  to  develop  consensus  criteria  may  be 
helpful.  The  next  step  is  to  identify  and  assess 
a  clear,  simple  set  of  consensus  criteria  that  the 
general  public  can  understand  and  use. 

Perioperative  Predictors  of  Extubation  Fail- 
ure and  the  Effect  on  Clinical  Outcome  after 
Cardiac  Surgery — Rady  MY,  Ryan  T.  Crit 
Care  Med  1999;27(2):340. 

OBJECTIVES:  To  determine  perioperative  pre- 
dictors of  extubation  failure  (requirement  for 
reintubation  and  mechanical  ventilation  after 
prior  successful  weaning  from  ventilator  sup- 
port and  extubation)  after  cardiac  surgery  and 
the  effect  on  clinical  outcome.  DESIGN:  Co- 
hort study.  SETTING:  A  tertiary-care,  54-bed, 
cardiothoracic  intensive  care  unit  (ICU).  PA- 
TIENTS: ICU  admissions  (n  =  11,330)  after 
cardiac  surgery  over  a  42-month  period.  IN- 
TERVENTIONS: Collection  of  preoperative, 
operative,  and  ICU  data  from  a  database.  MEA- 
SUREMENTS AND  MAIN  RESULTS:  Fre- 
quency of  extubation  failure,  total  duration  of 
mechanical  ventilation,  length  of  stay  in  ICU 
and  hospital,  and  death.  There  were  748  (6.6%) 
patients  who  were  weaned  from  mechanical  ven- 
tilation after  cardiac  surgery  and  required  rein- 
tubation and  ventilator  support.  The  predictors 
of  extubation  failure  were:  age  of  a:  65  yrs; 
inpatient  hospitalization  before  surgery;  arterial 
vascular  disease;  chronic  obstructive  pulmonary 
disease;  pulmonary  hypertension;  severe  left 
ventricular  dysfunction;  cardiac  shock;  hemat- 


ocrit of  £  34%;  blood  urea  nitrogen  of  a  24 
mg/dL;  serum  albumin  concentration  of  <  4.0 
g/dL  (£  40.0  g/  L);  systemic  oxygen  delivery 
of  £  320  mL/min/m^;  redo  operation;  surgical 
procedures  involving  the  thoracic  aorta;  trans- 
fusion of  blood  products  of  a  10  units;  and 
cardiopulmonary  bypass  time  of  a  120  mins. 
Extubation  failure  prolonged  the  length  of  total 
mechanical  ventilation,  as  well  as  ICU  and  hos- 
pital stay,  independent  of  the  frequency  of  or- 
gan dysfunction  or  nosocomial  infections  but 
did  not  increase  the  risk  of  death  after  cardiac 
surgery.  CONCLUSIONS:  Extubation  failure 
after  cardiac  surgery  is  uncommon.  Although 
extubation  failure  increa.sed  the  utilization  of 
ICU  and  hospital  resources,  it  did  not  affect 
mortality  after  cardiac  surgery.  Protocols  for 
early  extubation  and  ICU  discharge  should  be 
modified  in  the  presence  of  certain  preoperative 
and  operative  predictors  of  extubation  failure  to 
avoid  unnecessary  increase  in  the  cost  of  care 
after  cardiac  surgery. 

Immediate  Application  of  Positive-End  Ex- 
piratory Pressure  Is  More  Effective  than  De- 
layed Positive-End  Expiratory  Pressure  To 
Reduce  Extravascular  Lung  Water — Ruiz- 
Bailen  M,  Fernandez-Mondejar  E,  Hurtado- 
Ruiz  B,  Colmenero-Ruiz  M,  Rivera-Fernandez 
R.  Guerrero-Lopez  F,  Vazquez-Mata  G.  Crit 
Care  Med  1999;27(2):380. 

OBJECTIVE:  To  determine  by  the  measure- 
ment of  extravascular  lung  water  (EVLW) 
whether  the  timing  of  positive-end  expiratory 
pressure  (PEEP)  application  influences  the  in- 
tensity of  lung  injury.  DESIGN:  Animal  exper- 
imental study.  SETTING:  Animal  experimental 
laboratory.  SUBJECTS:  Mixed-breed  pigs  (n  = 
18),  aged  4  to  5  mos.  weighing  25  to  30  kg. 
INTERVENTIONS:  The  animals  were  anesthe- 
tized and  tracheotomized,  after  which  a  perme- 
ability pulmonary  edema  was  instigated  by  in- 
fusing oleic  acid  (0.1 /kg)  into  the  central  vein. 
All  animals  were  then  randomly  divided  into 
three  groups.  In  group  I  (n  =  5),  10  cm  HjO  of 
PEEP  was  applied  immediately  after  the  oleic 
acid  infusion  and  maintained  throughout  the  6 
hrs  of  the  experiment.  Group  2  (n  =  7)  received 
the  same  level  of  PEEP  120  mins  after  the  in- 
sult for  4  hrs.  Group  3  (n  =  6),  the  control 
group,  was  ventilated  without  PEEP  for  the  six 
hrs  of  the  experiment.  MEASUREMENTS 
AND  MAIN  RESULTS:  At  the  end  of  the  ex- 
periment, EVLW  was  calculated  by  gravimet- 
ric method.  EVLW  in  group  1(11 .46±2.00  mL/ 
kg)  was  significantly  less  than  in  group  2 
(19.12±2.62  mL/kg)  and  group  3  (25.81  ±  1.57 
mL/kg),  (p<  0.0001).  Oxygenation  also  showed 
important  differences  by  the  end  of  the  exper- 
iment when  the  PaoyPio,  ■'^''°  *^s  significantly 
better  in  group  1  (467±73)  than  in  group  2 
(180±82)  and  group  3  (39±9),  (p<  0.0001). 
CONCLUSIONS:  The  application  of  1 0  cm  H^O 
of  PEEP  reduces  EVLW  in  a  time-dependent 


Respiratory  Care  •  June  1999  Vol  43  No  6 


583 


Abstracts 


manner  and  maximum  protective  effect  is 
achieved  if  it  is  applied  immediately  after  lung 
injury  production. 

Allegations  of  Sexual  Abuse  in  an  Intensive 
Care  Unit — Hansen-Flaschen  J,  Adler  BS.  Crit 
Care  Med  1999;27(2):437. 

OBJECTIVES:  To  describe  misperceptions  of 
sexual  abuse  by  critically  ill.  sedated  patients 
undergoing  routine  perineal  care  in  an  intensive 
care  unit  and  to  offer  suggestions  for  address- 
ing patient  allegations  of  sexual  mistreatment 
in  this  setting.  DESIGN:  Case  reports  and  dis- 
cussion. SETTING:  Intermediate  care  unit  ex- 
tension of  a  medical  intensive  care  unit  at  a 
university  teaching  hospital.  PATIENTS:  A  57- 
yr-old  man  who  misperceived  rectal  intubation 
as  sexual  assault  while  receiving  intravenous 
lorazepam  for  sedation;  a  3 1  -yr-old  woman  who 
misinterpreted  a  perineal  bed  bath  as  sexual 
abu.se  while  receiving  lorazepam  and  fentanyl. 
INTERVENTIONS:  None.  CONCLUSIONS: 
Under  the  influence  of  commonly  used  psych- 
otropic drugs,  some  acutely  ill,  hospitalized  pa- 
tients misperceive  routine  perineal  care  as  sex- 
ual abuse.  Because  the  care  that  gives  rise  to 
mistaken  allegations  of  sexual  misconduct  is 
often  given  in  private,  and  because  sexual  abuse 
of  patients  sometimes  actually  occurs  in  hospi- 
tals, institutional  investigation  of  these  com- 
plaints is  both  sensitive  and  difficult.  Some  in- 
patient allegations  of  sexual  abuse  may  not  be 
resolvable  by  any  means.  Awareness  of  the  po- 
tential for  misinterpretation  of  perineal  care  may 
help  prevent  this  disturbing  phenomenon  and 
promote  fair,  reasoned  investigation  when  pa- 
tient complaints  of  sexual  abuse  do  arise  in  acute 
care  hospitals. 

Critical  Care  Services  and  Personnel:  Rec- 
ommendations Based  on  a  System  of  Cate- 
gorization into  Two  Levels  of  Care— Ameri- 
can College  of  Critical  Care  Medicine  of  the 
Society  of  Critical  Care  Medicine.  Crit  Care 
Med  1999;27(2):422. 

OBJECTIVES:  To  recommend  hospital  services 
and  personnel  requirements  for  the  provision  of 
optimal  care  to  critically  ill  patients.  Require- 
ments for  hospitals  with  comprehensive  re- 
sources, as  well  as  for  hospitals  with  limited 
resources,  are  addressed.  DATA  SOURCES:  a) 
Consensus  opinion  of  critical  care  physicians, 
nurses,  and  pharmacists:  and  b)  published  guide- 
lines of  organizational  and  administrative  top- 
ics addressing  the  provision  of  critical  care  by 
physicians  and  nurses,  the  pharmacologic  ap- 
proach to  the  critically  ill  patient,  and  diagnos- 
tic and  laboratory  testing  in  the  management  of 
critically  ill  patients.  CONCLUSION:  By  com- 
bining the  strengths  and  expertise  of  multidis- 
ciplinary  critical  care  specialists,  these  guide- 
lines provide  a  framework  in  which  hospitals  of 


varying  resources  may  optimize  the  care  of  crit- 
ically ill  patients. 

Early  and  Late  Acute  Respiratory  Distress 
Syndrome:  Two  Distinct  Clinical  Entities — 

Croce  MA,  Fabian  TC,  Davis  KA,  Gavin  TJ. 
J  Trauma  1999;46(3):361. 

BACKGROUND:  Despite  numerous  advances 
in  surgical  critical  care  and  ventilatory  manage- 
ment, mortality  rates  for  acute  respiratory  dis- 
tress syndrome  (ARDS)  have  remained  rela- 
tively constant.  Pressure-limited  and  non- 
pressure-limited  ventilatory  techniques  have 
been  advocated  with  disparate  results.  We  hy- 
pothesized that  there  are  two  forms  of  ARDS, 
which  may  account  for  the  conflicting  clinical 
reports.  METHODS:  Patients  with  posttrau- 
matic ARDS  were  identified  and  reviewed. 
ARDS  was  defined  as  Pao/Fio;  ratio  less  than 
200  with  diffuse  bilateral  infiltrates  on  chest 
radiograph  and  no  congestive  heart  failure.  Pa- 
tients were  analyzed  relative  to  injury  mecha- 
nism, transfusions,  fluid  balance,  presence  of 
pneumonia  (defined  as  a  10'  colony-forming 
unit.s/mL  in  bronchoalveolar  lavage  effluent), 
and  outcome.  All  were  managed  with  a  non- 
pressure-limited  strategy.  RESULTS:  During  a 
5.5-year  period,  178  patients  with  posttraumatic 
ARDS  were  identified.  Mean  Injury  Severity 
Score  and  age  were  29  and  40  years,  respec- 
tively. Patients  were  stratified  by  time  of  ARDS 
diagnosis.  Eighty-two  patients  (46%)  had  eariy 
ARDS  (within  48  hours  after  admission),  and 
96  patients  (54%)  had  late  ARDS  (>48  hours 
between  admission  and  diagnosis).  There  were 
no  differences  in  Injury  Severity  Score,  but  the 
late  group  was  significantly  older.  The  early 
ARDS  group  was  characterized  by  profound 
hemorrhagic  shock  and  had  significant  differ- 
ences from  the  late  group  in  incidence  of  pen- 
etrating injury  (30  vs.  10%;  p<0.001),  admis- 
sion base  deficit  (-7.7  vs.  -4.2  mEq/L;  p<0.001 ), 
48-hour  transfusions  (19.7  vs.  9.4;  p<0.000l), 
initial  5-day  fluid  balance  (19.9  vs.   10.1  L; 
p<0.000l),  and  initial  Pao/Fio^  (121  vs.  141; 
p<0.007).  Pneumonia  before  ARDS  was  sig- 
nificantly associated  with  late  ARDS  (38  vs. 
9%;  p<0.00l ).  ARDS-related  mortality  was  pri- 
marily caused  by  hemorrhagic  shock  in  the  early 
group  and  progressive  multiple  organ  failure  in 
the  late  group.  CONCLUSION:  There  are  two 
distinct  forms  of  posttraumatic  ARDS.  Early 
ARDS  is  characterized  by  hemorrhagic  shock 
with  capillary  leak.  Late  ARDS  frequently  fol- 
lows pneumonia  and  is  a.ssociated  with  multiple 
system  injury.  Further  studies  should  differen- 
tiate between  these  two  distinct  syndromes. 

Analysis  of  Inhaled  Corticosteroids  and  Oral 
Theophylline  Use  among  Patients  with  Sta- 
ble COPD  from  1987  to  1995— Van  Andel 
AE,  Reisner  C,  Menjoge  SS,  Witek  TJ.  Chest 
I999;I15(3):703. 


STUDY  OBJECTIVE:  To  document  temporal 
usage  trends  for  commonly  used  respiratory 
medications  in  patients  with  COPD.  DESIGN: 
We  retrospectively  evaluated  baseline  concom- 
itant medications  of  3,720  patients  with  COPD 
enrolled  in  10  bronchodilator  clinical  trials  from 
1987  to  1995.  The  proportion  of  patients  in 
each  trial  using  inhaled  corticosteroids,  inhaled 
beta-adrenergics,  inhaled  anticholinergics,  oral 
theophylline,  and  oral  corticosteroids  was  ana- 
lyzed using  the  Cochran-Armitage  trend  test. 
PATIENTS:  All  patients  had  stable,  moderate- 
to-severe  COPD  without  evidence  of  asthma  or 
atopy.  Reversibility  to  beta2-agonists  was  not  a 
requirement.  RESULTS:  The  percentage  of  pa- 
tients using  inhaled  corticosteroids  increased 
significantly  over  time  (p  <  0.001 )  from  1 3.2% 
in  1987  to  41.4%  in  1995.  The  percentage  of 
patients  receiving  oral  theophylline  decreased 
significantly  (p  <  0.001)  over  this  same  time 
interval  (63.4  to  29.0%).  In  addition,  the  per- 
centage of  patients  using  oral  corticosteroids 
and  the  percentage  using  oral  beta-adrenergics 
decreased  moderately  (p  <  0.05)  (30. 1  to  1 6.4% 
and  1 1 .7  to  4.5%,  respectively);  the  percentage 
of  patients  using  inhaled  anticholinergics  in- 
creased slowly  (p  <  0.05)  (48.2  to  53.8%).  The 
percentage  of  patients  receiving  inhaled  beta- 
adrenergics  did  not  significantly  (p  >  0.05) 
change.  CONCLUSIONS:  The  observed 
changes  in  use  of  inhaled  corticosteroids  and 
theophylline  were  not  likely  related  to  differ- 
ences in  disease  severity  or  other  patient  char- 
acteristics in  the  evaluated  trials,  but  related  to 
changing  prescribing  and  COPD  management 
practices. 

Associations  of  Smoking  with  Hospital-Based 
Care  and  Quality  of  Life  in  Patients  with 
Obstructive  Airway  Disease — Sippel  JM, 
Pedula  KL,  Vollmer  WM,  Buist  AS,  0.sborne 
ML.  Chest  1999;1I5(3):691. 

STUDY  OBJECTIVES:  To  investigate  the  re- 
lationship between  direct  or  environmental  to- 
bacco smoke  (ETS)  exposure  and  both  hospi- 
tal-based care  (HBC)  and  quality  of  life  (QOL) 
among  subjects  with  asthma.  STUDY  DESIGN: 
We  report  baseline  cross-.sectional  data  on  619 
subjects  with  asthma,  including  direct  or  ETS 
exposure  and  QOL,  and  prospective  longitudi- 
nal data  on  HBC  using  administrative  databases 
for  30  months  following  baseline  evaluation. 
SETTING  AND  PATIENTS:  Participants  were 
health  maintenance  organization  members  with 
physician-diagno.sed  asthma  involved  in  a  lon- 
gitudinal study  of  risk  factors  for  hospital-based 
asthma  care.  MEASUREMENTS:  Demo- 
graphic characteristics  and  QOL  were  assessed 
with  administered  questionnaires,  including  the 
Marks  Asthma  Quality-of-Life  (AQLQ)  and 
SF-36  questionnaires.  HBC  was  defined  as  ep- 
isodes per  person-year  of  hospital-based  asthma 
care,  which  included  emergency  department  and 
urgency  care  visits,  and  hospitalizations  for 


584 


Respiratory  Care  •  June  1999  Vol  43  No  6 


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Abstracts 


asthma.  RESULTS:  Current  smokers  reported 
significantly  worse  QOL  than  never-smokers  in 
two  of  five  domains  of  the  AQLQ  (p  <  0.05). 
Subjects  with  ETS  exposure  also  reported  sig- 
nificantly worse  QOL  than  those  without  ETS 
exposure  in  two  domains  (p  <  0.05).  On  the 
SF-36,  current  smokers  reported  significantly 
worse  QOL  than  never-smokers  in  five  of  nine 
domains  (p  <  0.05).  Subjects  with  ETS  expo- 
sure reported  significantly  worse  QOL  than 
those  without  ETS  exposure  in  three  domains 
(p  <  0.05).  Current  smokers  used  significantly 
more  hospital-based  asthma  care  than  never- 
smokers  (adjusted  relative  risk  [RR],  1.40;  95% 
confidence  interval  [CI],  1.01  to  1.95)  while 
ex-smokers  did  not  exhibit  increased  risk  com- 
pared with  nonsmokers  (adjusted  RR,  0.94;  95% 
CL  0.7  to  1.3).  Also,  subjects  with  ETS  expo- 
sure used  significantly  more  hospital-based 
asthma  care  than  tho.se  without  ETS  exposure 
(RR,  2.34;  95%  CL  1.80  to  3.05).  CONCLU- 
SIONS: Direct  or  environmental  tobacco  expo- 
sure prospectively  predicted  increased  health- 
care utilization  for  asthma  and  reduced  QOL  in 
patients  with  asthma.  These  findings  add  to  our 
existing  knowledge  of  the  detrimental  effects  of 
tobacco  smoke  and  are  of  relevance  specifically 
to  patients  with  asthma. 

Nocturnal  Asthma:  Effect  of  Salmeterol  on 
Quality  of  Life  and  Clinical  Outcomes — 

Lockey  RF,  DuBuske  LM,  Friedman  B,  Petro- 
cella  V,  Cox  F,  Rickard  K.  Chest  1999;1I5 
(3):666. 

OBJECTIVE:  To  evaluate  the  effect  of  salme- 
terol on  asthma-specific  quality  of  life  in  pa- 
tients experiencing  significant  nocturnal  symp- 
toms. DESIGN:  Randomized,  double-blind, 
placebo-controlled,  multicenter  clinical  trial. 
SETTING:  Allergy/respiratory  care  clinics.  PA- 
TIENTS: Nonsmokers  a  12  years  of  age  with 
nocturnal  asthma  symptoms  on  at  least  6  of  14 
days  during  screening  and  a  15%  decrease  in 
peak  expiratory  flow  (PEF)  from  baseline  on 
nocturnal  awakening  at  least  once  during  screen- 
ing. INTERVENTIONS:  Salmeterol,  42  microg, 
or  placebo  twice  daily.  Patients  were  allowed  to 
continue  theophylline,  inhaled  corticosteroids, 
and  "as-needed"  albuterol.  MEASUREMENTS 
AND  RESULTS:  Outcome  measures  included 
Asthma  Quality  of  Life  Questionnaire  (AQLQ) 
global  and  individual  domain  scores,  FEV,, 
PEF,  nighttime  awakenings,  asthma  symptoms, 
and  supplemental  albuterol  use.  Mean  change 
from  baseline  for  the  global  and  domain  AQLQ 
scores  was  significantly  greater  (p  s  0.005) 
with  salmeterol  compared  with  placebo.  At  week 
12,  salmeterol  significantly  (p  <  0.001  com- 
pared with  placebo)  increased  mean  change  from 
baseline  in  FEV,,  morning  and  evening  PEF, 
percentage  of  symptom-free  days,  percentage 
of  nights  with  no  awakenings  due  to  asthma, 
and  the  percentage  of  days  and  nights  with  no 
supplemental  albuterol  use.  Significant  im- 


provements in  PEF  were  observed  after  treat- 
ment with  salmeterol  regardless  of  concomitant 
treatment  with  theophylline  (p  <  0.05).  CON- 
CLUSIONS :  These  results  provide  evidence  that 
validates  the  role  of  salmeterol  in  improving 
quality  of  life  in  patients  with  moderate  persis- 
tent asthma  who  exhibited  nocturnal  asthma 
symptoms  and  supports  the  efficacy  of  salme- 
terol compared  with  that  of  placebo  (ie,  "as- 
needed"  albuterol). 


Long-Term  Cardiovascular  Safety  of  Salme- 
terol Powder  Pharmacotherapy  in  Adoles- 
cent and  Adult  Patients  with  Chronic  Per- 
sistent   Asthma:    A    Randomized    Clinical 

Trial— Chervinsky  P,  Goldberg  P,  Galant  S, 
Wang  Y,  Arledge  T,  Welch  MB,  Stahl  E.  Chest 
1999;115(3):642. 

STUDY  OBJECTIVES:  This  study  investigates 
the  long-term  cardiovascular  safety  of  salmet- 
erol powder  vs  placebo  in  adolescent  and  adult 
patients  with  mild  persistent  asthma.  DESIGN: 
Multicenter,  randomized,  double-blind,  place- 
bo-controlled, parallel-group  study.  SETTING: 
Eighteen  US  clinical  centers.  PATIENTS:  Three 
hundred  fifty-two  patients  (a  12  years)  with 
mild  persistent  asthma  (duration  a  6  months) 
requiring  pharmacotherapy;  with  FEV,  of  70  to 
90%  of  predicted  and  without  abnormal  ECG/ 
continuous  ambulatory  ECG  (Holter).  INTER- 
VENTIONS: Randomized  to  twice-daily  sal- 
meterol powder  (50  microg)  or  placebo  via 
breath-actuated  device  for  52  weeks.  Backup 
albuterol  was  available  to  control  asthma  symp- 
toms. MEASUREMENTS  AND  RESULTS: 
Cardiovascular  safety  was  regularly  assessed  by 
12-lead  ECG  with  a  15-s  lead  II  rhythm  strip, 
24-h  continuous  ambulatory  ECG  (Holter)  mon- 
itoring, serial  vital  sign  measurements,  and  re- 
view of  adverse  cardiovascular  events.  No 
deaths  occurred  during  the  study.  No  clinically 
significant  between-group  differences  were  ob- 
served in  pulse  rate,  ECG  QTc  interval,  median 
number  of  ventricular  or  supraventricular  ec- 
topic events,  incidence  of  ventricular  ectopic 
couplets  and  runs,  or  incidence  of  >  100  ven- 
tricular or  supraventricular  ectopic  events  in 
24  h.  No  clinically  significant  between-group 
differences  were  observed  in  arterial  BP  or  in- 
cidence of  adverse  cardiovascular  events.  Sal- 
meterol was  well  tolerated  throughout  the  52- 
week  study  period,  with  a  cardiovascular  safety 
profile  similar  to  that  of  placebo.  CONCLU- 
SIONS: Long-term,  twice-daily  pharmacother- 
apy with  salmeterol  powder  is  safe  and  is  not 
associated  with  unfavorable  clinically  signifi- 
cant changes  in  cardiac  function  or  increases  in 
cardiovascular  adverse  effects. 


Elevated  O2  Cost  of  Ventilation  Contributes 
to  Tissue  Wasting  in  COPD — Mannix  ET, 
ManfrediF.Farber  MO.  Chest  1999;1 15(3):708. 


BACKGROUND  AND  OBJECTIVES:  Thirty 
to  50%  of  all  COPD  patients  experience  tissue 
wasting  that  may  be  caused  by  hypermetabo- 
lism, but  the  cause  of  the  perturbed  metabolic 
state  is  unclear.  We  hypothesized  that  the  ele- 
vated O2  cost  of  ventilation  (O2  COV)  may  be 
a  contributing  factor.  All  of  the  data  are  pre- 
sented as  means  (±SEM).  Ten  hypoxemic  (a 
P„o,  of  54  ±3  mm  Hg)  stable  COPD  patients 
(an  FEV,/FVC  ratio  of  42±4%)  and  five  healthy 
control  subjects  were  studied.  The  patients  were 
divided  into  two  groups  based  on  nutritional 
status.  Group  1  (n  =  6)  was  malnourished  (a 
body  mass  index  [BMI]  of  17.6±0.7  kgW), 
and  group  2  (n  =  4)  was  normally  nourished  (a 
BMI  of  26.0±3  kg/m^).  The  Oj  COV  was 
determined  by  measuring  the  change  in  the  ox- 
ygen consumption  (Vq^  and  the  minute  venti- 
lation (Ve)  caused  by  CO^-induced  hyperven- 
tilafion.  RESULTS  AND  CONCLUSIONS: 
Group  1  had  an  elevated  O,  COV  when  com- 
pared to  group  2  and  the  control  group,  respec- 
tively: 16.4+1.0  vs  9.7±1.0  and  2.4+0.2  mL 
O2/L  of  Ve  (p  <  0.05).  The  Vq^  at  rest  was 
higher  for  group  1  than  for  group  2  and  the 
control  group,  respectively:  4.5  ±0.3  vs  3. 1  ±0.5 
and  3.4±0.2  mL/kg/min  (p  <  0.05).  The  rest- 
ing energy  expenditure  (REE)  %  predicted  for 
group  1  was  also  higher  than  group  2  and  the 
control  group,  respectively:  1 25 ± 3%  vs  87 ±7% 
and  97±2%  (p  <  0.05).  Significant  correla- 
tions were  observed  that  implicate  the  increased 
O2  COV  as  a  cause  of  tissue  wasting:  O2  COV 
vs  BMI  (r  =  -0.79;  p  =  0.007),  O2  COV  vs 
REE  %  predicted  (r  =  0.66;  p  =  0.039),  and 
REE  %  predicted  vs  BMI  (r  =  -0.83;  p  =  0.003). 
The  O2  COV  was  also  correlated  with  lung  func- 
don:  FEV|/FVC  vs  O2  COV  (r  =  -0.84;  p  = 
0.002).  We  conclude  that  in  these  COPD  pa- 
tients the  O2  COV  is  associated  with  an  in- 
creased metabolic  rate  which,  in  turn  adversely 
affects  the  nutritional  status. 

The  Snoring  Spectrum:  Acoustic  Assessment 
of  Snoring  Sound  Intensity  in  1,139  Individ- 
uals Undergoing  Polysomnography — Wilson 
K,  Stoohs  RA,  Mulrooney  TF,  Johnson  LJ,  Guil- 
leminault  C,  Huang  Z.  Chest  I999;l  15(3):762. 

STUDY  OBJECTIVES:  To  quantify  the  snor- 
ing sound  intensity  levels  generated  by  individ- 
uals during  polysomnographic  testing  and  to 
examine  the  relationships  between  acoustic, 
polysomnographic,  and  clinical  variables.  DE- 
SIGN: The  prospective  acquisition  of  acoustic 
and  polysomnographic  data  with  a  retrospec- 
tive medical  chart  review.  SETTING:  A  sleep 
laboratory  at  a  primary  care  hospital.  PARTIC- 
IPANTS: All  1,139  of  the  patients  referred  to 
the  sleep  laboratory  for  polysomnographic  test- 
ing from  1 980 to  1 994.  INTERVENTIONS:  The 
acoustic  measurement  of  snoring  sound  inten- 
sity during  sleep  concurrent  with  polysomno- 
graphic testing.  MEASUREMENTS  AND  RE- 
SULTS: Four  decibel  levels  were  derived  from 


586 


Respiratory  Care  •  June  1999  Vol  43  No  6 


Abstracts 


snoring  sound  intensity  recordings.  LI,  L5,  and 
LIO  are  measures  of  the  sound  pressure  mea- 
surement in  decibels  employing  the  A-weight- 
ing  network  that  yields  the  response  of  the  hu- 
man ear  exceeded,  respectively,  for  I,  5,  and 
10%  of  the  test  period.  The  Leq  is  a  measure  of 
the  A-weighted  average  intensity  of  a  fluctuat- 
ing acoustic  signal  over  the  total  test  period. 
LIO  levels  above  55  dBA  were  exceeded  by 
12.3%  of  the  patients.  The  average  levels  of 
snoring  sound  intensity  were  significantly  higher 
for  men  than  for  women.  The  levels  of  snoring 
sound  intensity  were  associated  significantly 
with  the  following:  polysomnographic  testing 
results,  including  the  respiratory  disturbance  in- 
dex (RDI),  sleep  latency,  and  the  percentage  of 
slow-wave  sleep;  demographic  factors,  includ- 
ing gender  and  body  mass;  and  clinical  factors, 
including  snoring  history,  hypersomnolence, 
and  breathing  stoppage.  Men  with  a  body  mass 
index  of  >  30  and  an  average  snoring  sound 
intensity  of  >  38  dBA  were  4.1  times  more 
likely  to  have  an  RDI  of  >  1 0.  CONCLUSIONS: 
Snoring  sound  intensity  levels  are  related  to  a 
number  of  demographic,  clinical,  and  polysom- 
nographic test  results.  Snoring  sound  intensity 
is  closely  related  to  apnea/hypopnea  during 
sleep.  The  noise  generated  by  snoring  can  dis- 
turb or  disrupt  a  snorer's  sleep,  as  well  as  the 
sleep  of  a  bed  partner. 

Positional  Treatment  vs  Continuous  Positive 
Airway  Pressure  in  Patients  witii  Positional 
Obstructive  Sleep  Apnea  Syndrome — Jokic 
R,  Klimaszewski  A,  Crossley  M,  Sridhar  G, 
Fitzpatrick  MF.  Che.st  I999;l  15(3):77l. 

OBJECTIVES:  The  aim  of  this  study  was  to 
compare  the  relative  efficacy  of  continuous  pos- 
itive airway  pressure  (CPAP)  and  positional 
treatment  in  the  management  of  positional  ob- 
structive sleep  apnea  (OSA),  using  objective 
outcome  measures.  DESIGN:  A  prospective, 
randomized,  single  blind  crossover  comparison 
of  CPAP  and  positional  treatment  for  2  weeks 
each.  SETTING:  A  university  teaching  hospi- 
tal. PATIENTS:  Thirteen  patients  with  posi- 
tional OSA,  aged  (mean±SD)  5 1  ±9  years,  with 
an  apnea-hypopnea  index  (AHI)  of  1 7  ±  8.  MEA- 
SUREMENTS: (1)  Daily  Epworth  Sleepiness 
Scale  scores;  (2)  overnight  polysomnography, 
an  objective  assessment  of  sleep  quality  and 
AHI;  (3)  maintenance  of  wakefulness  testing; 
(4)  psychometric  test  battery;  (5)  mood  scales; 
(6)  quality-of-life  questionnaires;  and  (7)  indi- 
vidual patient's  treatment  preference.  RE- 
SULTS: Positional  treatment  was  highly  effec- 
tive in  reducing  time  spent  supine  (median,  0; 
range,  0  to  32  min).  The  AHI  was  lower  (mean 
difference,  6.1;  95%  confidence  interval  [CI],  2 
to  10.2;  p  =  0.007),  and  the  minimum  oxygen 
saturation  was  higher  (4%;  95%  CI,  1%  to  8%; 
p  =  0.02)  on  CPAP  as  compared  with  posi- 
tional treatment.  There  was  no  significant  dif- 
ference, however,  in  sleep  architecture,  Epworth 


Sleepiness  Scale  scores,  maintenance  of  wake- 
fulness testing  sleep  latency,  psychometric  test 
performance,  mood  scales,  or  quality-of-life 
measures.  CONCLUSION:  Positional  treatment 
and  CPAP  have  similar  efficacy  in  the  treat- 
ment of  patients  with  positional  OSA. 

Venovenous  Extracorporeal  Life  Support  via 
Percutaneous  Cannulation  in  94  Patients — 

Pranikoff  T,  HirschI  RB,  Remenapp  R,  Swani- 
ker  F,  Bartlett  RH.  Chest  1999;1 15(3):818. 

STUDY  OBJECTIVE:  The  objective  of  this 
study  was  to  demonstrate  the  safety  and  utility 
of  a  method  of  percutaneous  access  for  cannu- 
lation of  adult  patients  for  venovenous  extra- 
corporeal life  support  (ECLS).  DESIGN:  A  ret- 
rospective review  of  a  patient  series.  SETTING: 
A  surgical  ICU  at  a  university  teaching  hospi- 
tal. PATIENTS:  The  study  group  consisted  of 
94  adults  >  17  years  old  with  respiratory  fail- 
ure who  were  placed  on  venovenous  ECLS  by 
means  of  percutaneous  cannulation.  INTER- 
VENTIONS: The  cannulation  of  the  internal 
jugular  and  femoral  veins  (FVs)  using  the 
Seldinger  technique  for  venovenous  ECLS. 
MEASUREMENTS  AND  RESULTS:  Between 
May  1992  and  November  1997,  we  performed 
percutaneous  cannulation  for  venovenous  ECLS 
in  94  adult  patients  with  respiratory  failure.  The 
mean  (±  SD)  age  was  36. 1±  12.7  years  old 
(range,  1 7  to  65  years).  The  mean  ( ±  SD)  weight 
was  80.7  ±22.3  kg  (range,  36  to  156  kg).  The 
right  internal  jugular  vein  (RIJV)  was  used  for 
venous  drainage  access  in  all  but  four  cases. 
The  right  FV  (n  =  86),  the  left  FV  (n  =  3),  or 
the  RIJV  (n  =  4)  was  utilized  for  venous  rein- 
fusion.  The  maximum  blood  flow  (±SD)  dur- 
ing ECLS  was  57.6±17.5  mL/kg/min  (range, 
22.4  to  127.8  mL/kg/min),  with  a  postmem- 
brane  outlet  pressure  (±SD)  of  146  ±43  mm 
Hg  (range,  56  to  258  mm  Hg)  at  the  maximum 
flow  rate.  There  were  1 1  unsuccessful  percuta- 
neous cannulation  attempts.  In  three  patients 
(3%),  the  complications  consisted  of  arterial  in- 
jury requiring  operative  cutdown  and  repair.  In 
six  patients  (6%),  cannula-site  bleeding  required 
pursestring  suture  reinforcement  of  the  cannula 
site.  One  patient  died  from  the  perforation  of 
the  superior  vena  cava  during  cannulation.  CON- 
CLUSIONS: Based  on  these  data,  we  conclude 
that  percutaneous  cannulation  may  be  utilized 
to  provide  venovenous  ECLS  in  adults. 

Timing  of  Referral  for  Lung  Transplanta- 
tion for  Cystic  Fibrosis:  Overemphasis  on 
FEV,  May  Adversely  Affect  Overall  Surviv- 
al—Doershuk  CF,  Stem  RC.  Chest  1999;  115 

(3):782. 

STUDY  OBJECTIVES:  (1)  Report  our  experi- 
ence with  referral  for  lung  transplantation.  (2) 
Review  survival  in  cvstic  fibrosis  (CF)  patients 
without  lung  transplantation  after  FEV,  re- 
mains <  30%  predicted  for  1  years.  DESIGN: 


Retrospective  review.  SETTING:  A  university 
hospital  CF  center.  PATIENTS:  (1)  Forty-five 
patients  referred  for  lung  transplantation  eval- 
uation, and  (2)  178  patients  without  Burkhold- 
eria  sp  infection,  with  the  above  FEV,  criterion. 
MAIN  OUTCOME  MEASURE:  Survival. 
MEASUREMENTS  AND  RESULTS:  (1 )  One- 
and  2-year  survival  after  transplantation  was 
55%  and  45%,  respectively.  However,  among 
patients  without  transplants  with  FEV,  <  30% 
predicted,  median  survival,  1986  to  1990,  ie, 
before  the  transplant  era,  was  4.6  years  with 
25%  living  >  9  years  (before  1986, 25%  lived  > 
6  years).  (2)  Survival  after  transplantation  was 
not  correlated  to  any  of  the  following:  age,  sex, 
genotype,  FEV,  percent  predicted,  insulin-de- 
pendent diabetes  mellitus,  or  with  waiting  time 
before  transplantation,  and  did  not  seem  to  be 
correlated  to  serum  bicarbonate  or  percent  ideal 
body  weight.  Four  of  five  patients  already  in- 
fected with  Burkholderia  species  died  within  5 
months  of  transplantation;  the  fifth  died  at  17 
months.  All  five  died  of  pulmonary  or  extrapul- 
monary infection  with  Burkholderia  species 
CONCLUSIONS:  Use  of  FEV,  <  30%  pre- 
dicted to  automatically  establish  transplantation 
eligibility  could  lead  to  decreased  overall  sur- 
vival for  CF  patients.  Referral  for  evaluation 
and  transplantation  should  also  be  based  on  ox- 
ygen requirement,  rate  of  deterioration,  respi- 
ratory microbiology,  quality  of  life,  frequency 
of  IV  antibiotic  therapy,  and  other  consider- 
ations. If  pulmonary  status  has  unexpectedly 
improved  when  the  patient  is  at  or  near  the  top 
of  the  waiting  list,  total  survival  may  be  im- 
proved by  "inactivating  the  patient'"  until  pro- 
gression is  again  evident. 

A  Critical  Review  of  the  Studies  of  the  Ef- 
fects of  Simulated  or  Real  Gastroesophageal 
Reflux  on  Pulmonary  Function  in  Asthmatic 
Adults— Field  SK.  Chest  1999;1 15(3):848. 

OBJECTIVE:  To  identify  and  critically  review 
the  published  peer-reviewed,  English-language 
studies  of  the  effects  of  both  spontaneous  and 
simulated  gastroesophageal  reflux  (GER)  on 
pulmonary  function  in  asthmatic  adults.  DE- 
SIGN: U.sing  the  1966  to  1997  MEDLINE  da- 
tabase, the  terms  asthma  and  lung  disease  were 
combined  with  GER  to  identify  studies  of  the 
effects  of  GER  and  acid  perfusion  (AP)  of  the 
esophagus  on  pulmonary  function.  The  bibliog- 
raphies were  also  reviewed.  Studies  of  asthmat- 
ics with  and  without  symptomatic  GER  were 
analyzed  both  together  and  separately.  RE- 
SULTS: A  total  of  254  citations,  including  180 
published  in  English,  were  identified.  Among 
these  were  18  studies  of  GER  and  AP  in  asth- 
matic adults.  These  reports,  which  contain  data 
on  312  asthmatics,  found  that  the  FEV,  and  the 
midexpiratory  rate  did  not  change  during  AP 
and  GER  in  the  studies  containing  97%  and 
94%  of  the  asthmatics,  respectively.  Flow  vol- 
ume loop  indexes,  including  the  flow  at  50%  of 


Respiratory  Care  •  June  1999  Vol  43  No  6 


587 


Abstracts 


the  vital  capacity  (V50),  flow  at  25%  of  the  vital 
capacity,  and  the  peak  expiratory  flow  rate,  did 
not  change  during  AP  or  GER  in  the  studies 
with  77%,  60%,  and  65%  of  the  asthmatics, 
respectively.  Small  changes  in  the  resistance 
were  reported  in  the  studies  containing  42%  of 
the  asthmatics.  Among  asthmatics  without 
symptomatic  GER,  no  changes  in  spirometry, 
resistance,  and  flow  volume  indexes  were  found, 
except  for  a  10%  decline  in  V50  in  one  study 
with  seven  subjects.  CONCLUSIONS:  In  asth- 
matics with  GER,  the  effects  of  AP  on  pulmo- 
nary function  are  minimal,  and  only  a  minority 
are  affected.  The  literature  does  not  support  the 
conclusion  that  asymptomatic  reflux  contributes 
to  worsening  lung  function. 

Indications  for  Positive  Airway  Pressure 
Treatment  of  Adult  Obstructive  Sleep  Ap- 
nea Patients:  A  Consensus  Statement — Loube 
DI,  Gay  PC,  Strohl  KP,  Pack  AI,  White  DP, 
Collop  NA.  Chest  1999;1 15(3):863. 

We  developed  a  short-length  document  that 
clearly  delineates  a  prudent  approach  to  and 
criteria  for  reimbursement  of  positive  airway 
pressure  (PAP)  costs  for  the  treatment  of  ob- 
structive sleep  apnea  (OSA).  Treatment  modal- 
ities for  OSA  with  PAP  include  continuous  pos- 
itive airway  pressure,  bilevel  or  variable  PAP, 
and  autotitrating  PAP.  This  guidance  on  the 
appropriate  criteria  for  PAP  use  in  OSA  is  based 
on  widely  acknowledged  peer-reviewed  studies 
and  widely  accepted  clinical  practice.  These  cri- 
teria reflect  current  opinion  on  the  appropriate 
clinical  management  of  OSA  in  lieu  of  data 
pending  from  the  Sleep  Heart  Health  Study  and 
upcoming  outcome  studies.  This  document  is 
not  intended  to  provide  a  complete  review  and 
analysis  of  the  OSA  clinical  literature.  The  key 
to  the  success  of  this  document  is  to  foster  con- 
sensus within  and  outside  the  clinical  sleep  com- 
munity by  providing  a  common  sense  and  eas- 
ily understood  approach  to  the  treatment  of  OSA 
with  PAP. 

How  Accurate  Is  Spirometry  at  Predicting 
Restrictive  Pulmonary  Impairment? — Aaron 
SD,  Dales  RE,  Cardinal  P.  Chest  1999;l  15(3): 
869-873. 

OBJECTIVE:  To  determine  the  accuracy  with 
which  spirometric  measurements  of  FVC  and 
expiratory  flow  rates  can  diagnose  the  presence 
of  a  restrictive  impairment.  DESIGN:  The  pul- 
monary function  tests  of  1 ,83 1  consecutive  white 
adult  patients  who  had  undergone  both  spirom- 
etry and  lung  volume  measurements  on  the  same 
visit  over  a  2-year  period  were  analyzed.  The 
probability  of  restrictive  pulmonary  impairment, 
defined  as  a  reduced  total  lung  capacity  (TLC) 
below  the  lower  limit  of  the  95%  confidence 
interval,  was  determined  for  each  of  several 
categoric  classifications  of  the  spirometric  data, 
and  additionally  for  each  of  several  interval  lev- 


els of  the  FVC  and  the  FEV,/FVC  ratio.  SET- 
TING: A  large  clinical  laboratory  in  a  univer- 
sity teaching  hospital  using  quality-assured  and 
standardized  spirometry  and  lung  volume  mea- 
surement techniques  according  to  American 
Thoracic  Society  standards.  RESULTS:  Two 
hundred  twenty-five  of  1,831  patients  (12.3%) 
had  a  restrictive  defect.  The  positive  predictive 
value  of  spirometry  for  predicting  restriction 
was  relatively  low;  of  470  patients  with  a  low 
FVC  on  spirometry,  only  41%  had  restriction 
confirmed  on  lung  volume  measurements.  When 
the  analysis  was  confined  to  the  264  patients 
with  a  restrictive  pattern  on  spirometry  (ie,  low 
FVC  and  normal  or  above  normal  FEV|/FVC 
ratio),  the  positive  predictive  value  was  58%. 
Conversely,  spirometry  had  a  very  favorable 
negative  predictive  value;  only  2.4%  of  patients 
(32  of  1,361)  with  a  normal  vital  capacity  (VC) 
on  spirometry  had  a  restrictive  defect  by  TLC 
measurement.  The  probability  of  a  restrictive 
defect  was  directly  and  linearly  related  to  the 
degree  of  reduction  of  FVC  when  the  FVC  was 
<  80%  of  predicted  (p  =  0.002).  Combining 
the  FVC  and  the  FEV,/FVC  ratio  improved  the 
predictive  ability  of  spirometry;  for  all  values 
of  FVC  <  80%  of  the  predicted  amount,  the 
likelihood  of  restrictive  disease  increased  as  the 
FEV,/FVC  ratio  increased.  CONCLUSIONS: 
Spirometry  is  very  useful  at  excluding  a  restric- 
tive defect.  When  the  VC  is  within  the  normal 
range,  the  probability  of  a  restrictive  defect  is  < 
3%,  and  unless  restrictive  lung  disease  is  sus- 
pected a  priori,  measurement  of  lung  volumes 
can  be  avoided.  However,  spirometry  is  not  able 
to  accurately  predict  lung  restriction;  <  60%  of 
patients  with  a  classical  spirometric  restrictive 
pattern  had  pulmonary  restriction  confirmed  on 
lung  volume  measurements.  For  these  patients, 
measurement  of  the  TLC  is  needed  to  confirm 
a  true  restrictive  defect. 

Perceived  Risl(s  of  Heart  Disease  and  Can- 
cer among  Cigarette  Smokers — Ayanian  JZ, 
Cleary  PD.  JAMA  1999;281(l  1):1019. 

CONTEXT:  Cigarette  smoking  causes  more  pre- 
ventable deaths  from  cardiovascular  disease  and 
cancer  than  any  other  modifiable  risk  factor, 
but  smokers  may  discount  the  increased  per- 
sonal risk  they  face  from  continued  smoking. 
OBJECTIVE:  To  assess  smokers'  perceptions 
of  their  risks  of  heart  disease  and  cancer.  DE- 
SIGN AND  SETTING:  Telephone  and  self-ad- 
ministered survey  in  1995  of  a  probability  sam- 
ple of  US  households  with  telephones. 
PARTICIPANTS:  A  total  of  3031  adults  aged 
25  to  74  years,  including  737  current  smokers 
(24.3%).  MAIN  OUTCOME  MEASURES:  Re- 
spondents with  no  history  of  myocardial  infarc- 
tion (MI)  (96.2%)  or  cancer  (92.9%)  assessed 
their  risk  of  these  conditions  relative  to  other 
people  of  the  same  age  and  sex.  Among  current 
smokers,  perceived  risks  were  analyzed  by  de- 
mographic and  clinical  factors  using  logistic  re- 


gression. RESULTS:  Only  29%  and  40%  of 
current  smokers  believed  they  have  a  higher- 
than-average  risk  of  MI  or  cancer,  respectively, 
and  only  39%  and  49%  of  heavy  smokers  (a  40 
cigarettes  per  day)  acknowledged  these  risks. 
Even  among  smokers  with  hypertension,  an- 
gina, or  a  family  history  of  MI,  48%,  49%,  and 
39%,  respectively,  perceived  their  risk  of  MI  as 
higher  than  average.  In  multivariate  analyses, 
older  (a  65  years),  less  educated  (<  high  school 
graduate),  and  light  smokers  (1-19  cigarettes 
per  day)  were  less  likely  than  younger,  more 
educated,  and  heavy  smokers  to  perceive  an 
increased  personal  risk  of  MI  or  cancer.  CON- 
CLUSIONS: Most  smokers  do  not  view  them- 
selves at  increased  risk  of  heart  disease  or  can- 
cer. As  part  of  multifaceted  approaches  to 
smoking  cessation,  physicians  and  public  health 
professionals  should  identify  and  educate  smok- 
ers who  are  not  aware  of  smoking-related  health 
risks.  ■  ' 

Improved  Pulmonary  Distribution  of  Recom- 
binant Human  Cu/Zn  Superoxide  Dismutase, 
Using  a  Modified  Ultrasonic  Nebulizer — 

Langenback  EG,  Davis  JM,  Robbins  C,  Sahgal 
N,  Perry  RJ,  Simon  SR.  Pediatr  Pulmonol  1999; 

27(2):  124. 

Prophylactic,  intratracheal  instillation  of  recom- 
binant human  Cu/Zn  superoxide  dismutase  (rh- 
SOD)  has  been  shown  to  lessen  lung  injury 
produced  by  48  h  of  hyperoxia  and  mechanical 
ventilation  in  neonatal  pigleis.  However,  instil- 
lation of  small  volumes  of  rhSOD  intratrache- 
ally  would  not  be  expected  to  result  in  uniform 
pulmonary  distribution.  Aerosolization  is  a  tech- 
nique that  may  improve  pulmonary  distribution 
of  drugs,  but  is  limited  by  the  poor  efficiency  of 
most  nebulizers.  A  newly  modified  ultrasonic 
nebulizer  was  tested  to  assess  pulmonary  dis- 
tribution of  rhSOD  compared  to  that  achieved 
by  intratracheal  instillation.  rhSOD  was  dual- 
labeled  with  technetium-99m  (99mTc)  and  a 
fluorescent  analog  (permitting  quantitative  and 
qualitative  assessments  of  pulmonary  distribu- 
tion), and  administered  to  neonatal  piglets  by 
intratracheal  instillation  or  by  aerosolization.  In- 
tratracheal instillation  of  rhSOD  to  piglets  when 
supine  resulted  in  nonuniform  distribution,  with 
most  of  the  drug  being  found  in  the  right  caudal 
lobe,  and  localized  in  airways.  Placing  animals 
in  30  degrees  of  Trendelenburg  and  adminis- 
tering half  the  dose  in  the  left  and  half  in  the 
right  lateral  decubitus  positions  improved  dis- 
tribution, but  alveolar  deposition  remained 
patchy.  Aerosolization  using  a  modified  ultra- 
sonic nebulizer  uniformly  delivered  45.8  ± 
3.8%  of  the  rhSOD  to  the  lungs  that  had  been 
placed  in  the  nebulizer.  The  rhSOD  was  still 
active  and  present  in  airways  and  alveoli  in  a 
homogeneous  fashion.  We  conclude  that  intra- 
tracheal instillation  of  rhSOD  in  small  volumes 
results  in  nonuniform  pulmonary  distribution, 
while  aerosolization  enhances  rhSOD  distribu- 


588 


Respiratory  Care  •  June  1999  Vol  43  No  6 


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Abstracts 


tion  and  alveolar  deposition.  This  has  important 
implications  for  ongoing  clinical  trials  of  rh- 
SOD  for  the  prevention  of  acute  and  chronic 
lung  injury  in  premature  neonates. 

Probable  Transmission  of  HIV  from  an  Or- 
thopedic Surgeon  to  a  Patient  in  France — 

Lot  F,  Seguier  JC,  Fegueux  S,  Astagneau  P, 
Simon  P,  Aggoune  M,  et  al.  Ann  Intern  Med; 
130(1):1. 

BACKGROUND:  Transmission  of  HIV  from 
infected  health  care  workers  to  patients  has  been 
documented  in  only  one  cluster  involving  6  pa- 
tients of  a  dentist  in  Florida.  In  October  1995, 
the  French  Ministry  of  Health  offered  HIV  test- 
ing to  patients  who  had  been  operated  on  by  an 
orthopedic  surgeon  in  whom  AIDS  was  recently 
diagnosed.  OBJECTIVE:  To  determine  whether 
the  surgeon  transmitted  HIV  to  patients  during 
operations.  DESIGN:  Epidemiologic  investiga- 
tion. SETTING:  The  practice  of  an  orthopedic 
surgeon  in  a  French  public  hospital.  PARTIC- 
IPANTS: 1  surgeon  and  983  of  his  former  pa- 
tients. MEASUREMENTS:  3004  patients  who 
had  undergone  invasive  procedures  were  con- 
tacted by  mail  for  counseling  and  HIV  testing. 
One  HIV-positive  patient  was  interviewed,  and 
DNA  sequence  analysis  was  performed  to  com- 
pare the  genetic  relation  of  the  patient's  and  the 
surgeon's  viruses.  Infection-control  precautions 
and  the  surgeon's  practices  were  assessed.  RE- 
SULTS: Of  983  patients  in  whom  serologic  sta- 
tus was  ascertained,  982  were  HIV  negative 
and  I  was  HIV  positive.  The  HIV-positive  pa- 
tient, a  woman  born  in  1925,  tested  negative  for 
HIV  before  placement  of  a  total  hip  prosthesis 
with  bone  graft  (a  prolonged  operation)  per- 
formed by  the  surgeon  in  1992.  She  had  no 
identified  risk  for  HIV  exposure.  Molecular 
analysis  indicated  that  the  viral  sequences  ob- 
tained from  the  surgeon  and  the  HIV-infected 
woman  were  closely  related.  Infection-control 
precautions  were  in  accordance  with  recommen- 
dations, but  blood  contact  between  the  surgeon 
and  his  patients  occurred  commonly  during  sur- 
gical procedures.  CONCLUSIONS:  An  HIV- 
infected  surgeon  may  have  transmitted  HIV  to 
one  of  his  patients  during  surgery.  See  the  re- 
lated editorial:  Provider-to-Patient  HIV  Trans- 
mission: How  to  Keep  it  Exceedingly  Rare. 
Gerberding  J.  Ann  Intern  Med  1999:130(1): 
64-65. 

End-of-Life  Care  in  Medical  Textboolis — 

Carron  AT,  Lynn  J,  Keaney  P.  Ann  Intern  Med 
1999;130(1):82. 

Improvement  in  end-of-life  care  has  become  a 
demand  of  the  public  and  a  priority  for  health 
care  professionals.  Medical  textbooks  could  sup- 
port this  improvement  by  functioning  as  edu- 
cational resources  and  as  reference  material.  In 


this  paper,  four  widely  used  general  medical 
textbooks  are  assessed  for  their  coverage  of  nine 
content  domains  for  1 2  illnesses  that  often  cause 
death;  each  domain  in  each  disease  and  in  each 
text  was  graded  for  presence  and  helpfulness  of 
advice.  Helpful  information  was  rare,  and  only 
prognostication  and  medical  treatments  to  alter 
the  course  of  the  disease  were  usually  men- 
tioned. Harrison's  Textbook  of  Medicine,  The 
Merck  Manual,  and  Scientific  American  Medi- 
cine often  mentioned  at  least  a  few  of  the  do- 
mains in  each  disease,  although  not  often  in  a 
way  that  would  guide  a  clinician.  Manual  of 
Medical  Therapeutics  (The  Washington  Man- 
ual) includes  little  information  about  end-of- 
life  care.  Improvement  seems  possible.  Short 
additions  of  information  on  end-of-life  care 
would  probably  be  effective.  Many  chapters  dis- 
cussed at  length  certain  topics  that  are  clearly 
optional;  other  textbooks  addressed  these  topics 
only  briefly.  When  dealing  with  end-of-life  care, 
physicians  should  seek  guidance  from  other 
sources  and  textbook  authors  and  editors  should 
improve  the  utility  and  completeness  of  their 
texts. 


Effect  of  Inhaled  Nitric  Oxide  on  Gas  Ex- 
change in  Patients  with  Congestive  Heart 
Failure:  A  Randomized,  Controlled  Trial — 

Matsumoto  A,  Momomura  S,  Sugiura  S,  Fujita 
H,  Aoyagi  T,  Sata  M,  et  al.  Ann  Intern  Med 
1999;130(1):40. 

BACKGROUND:  Conventional  vasodilators 
increase  ventilation-perfusion  mismatch  and  do 
not  improve  gas  exchange  even  though  they 
reduce  pulmonary  hypertension.  However,  the 
effects  of  nitric  oxide  inhalation  on  ventilatory 
and  gas  exchange  values  in  patients  with  con- 
gestive heart  failure  are  not  known.  OBJEC- 
TIVE: To  investigate  the  effect  of  nitric  oxide 
inhalation  on  gas  exchange  in  patients  with  con- 
gestive heart  failure.  DESIGN:  Randomized, 
controlled  trial.  SETTING:  University  hospital. 
PATIENTS:  16  patients  with  congestive  heart 
failure  (New  York  Heart  Association  class  II  or 
III).  INTERVENTIONS:  Patients  inhaled  nitric 
oxide  gas  at  graded  concentrations  (n  =  8)  or 
were  given  intravenous  isosorbide  dinitrate,  2.5 
mg  (n  =  8).  MEASUREMENTS:  Hemody- 
namic and  ventilatory  variables  and  blood  gases 
were  measured  5  minutes  after  inhalation  of 
different  doses  of  nitric  oxide  and  10  minutes 
after  administration  of  isosorbide  dinitrate.  RE- 
SULTS: Nitric  oxide  inhalation  reduced  the 
mean  pulmonary  arterial  pressure  in  a  dose- 
dependent  manner  without  altering  the  mean 
arterial  pressure  or  cardiac  output.  At  a  dose  of 
40  parts  per  million,  nitric  oxide  inhalation  in- 
creased P„o,  (change  from  baseline,  12.0  mm 
Hg  [95%  CI,  2.3  to  21.7  mm  Hg];  p  =  0.014) 
and  decreased  the  alveolar-arterial  difference  in 
partial  pressure  of  oxygen  (change,  -8.6  mm  Hg 


[CI,  -16.8  to  -0.4  mm  Hg];  p  =  0.038)  and  the 
ventilatory  equivalent  for  carbon  dioxide  out- 
put (change,  -6.7  [CI,  -10.3  to  -3.1];  p  <  0.001). 
Although  isosorbide  dinitrate  similarly  de- 
creased pulmonary  arterial  pressure,  it  did  not 
alter  gas  exchange  or  ventilatory  variables. 
CONCLUSIONS:  Because  nitric  oxide  inhala- 
tion improved  gas  exchange,  it  may  be  used  as 
a  supportive  therapy  when  other  conventional 
vasodilators  worsen  gas  exchange. 

A  Comparison  of  Two  Antimicrobial-Im- 
pregnated Central  Venous  Catheters.  Cath- 
eter Study  Group — Darouiche  RO,  Raad  II, 
Heard  SO,  Thornby  JI,  Wenker  OC,  Gabrielli 
A,  et  al.  N  Engl  J  Med  1999;340(1):1 

BACKGROUND:  The  use  of  central  venous 
catheters  impregnated  with  either  minocycline 
and  rifampin  or  chlorhexidine  and  silver  sulfa- 
diazine reduces  the  rates  of  catheter  coloniza- 
tion and  catheter-related  bloodstream  infection 
as  compared  with  the  use  of  unimpregnated  cath- 
eters. We  compared  the  rates  of  catheter  colo- 
nization and  catheter-related  bloodstream  infec- 
tion associated  with  these  two  kinds  of 
antiinfective  catheters.  METHODS:  We  con- 
ducted a  prospective,  randomized  clinical  trial 
in  12  university-affiliated  hospitals.  High-risk 
adult  patients  in  whom  central  venous  catheters 
were  expected  to  remain  in  place  for  three  or 
more  days  were  randomly  assigned  to  undergo 
insertion  of  polyurethane,  triple-lumen  cathe- 
ters impregnated  with  either  minocycline  and 
rifampin  (on  both  the  luminal  and  external  sur- 
faces) or  chlorhexidine  and  silver  sulfadiazine 
(on  only  the  external  surface).  After  their  re- 
moval, the  tips  and  subcutaneous  segments  of 
the  catheters  were  cultured  by  both  the  roll- 
plate  and  the  sonication  methods.  Peripheral- 
blood  cultures  were  obtained  if  clinically  indi- 
cated. RESULTS:  Of  865  catheters  inserted,  738 
(85  percent)  produced  culture  results  that  could 
be  evaluated.  The  clinical  characteristics  of  the 
patients  and  the  risk  factors  for  infection  were 
similar  in  the  two  groups.  Catheters  impreg- 
nated with  minocycline  and  rifampin  were  1/3 
as  likely  to  be  colonized  as  catheters  impreg- 
nated with  chlorhexidine  and  silver  sulfadia- 
zine (28  of  356  catheters  [7.9  percent]  vs.  87  of 
382  [22.8  percent],  p<0.00l),  and  catheter-re- 
lated bloodstream  infection  was  1/12  as  likely 
in  catheters  impregnated  with  minocycline  and 
rifampin  (I  of  356  [0.3  percent],  vs.  13  of  382 
[3.4  percent]  for  those  impregnated  with  chlo- 
rhexidine and  silver  sulfadiazine;  p<0.002). 
CONCLUSIONS:  The  use  of  central  venous 
catheters  impregnated  with  minocycline  and  ri- 
fampin is  associated  with  a  lower  rate  of  infec- 
tion than  the  use  of  catheters  impregnated  with 
chlorhexidine  and  silver  sulfadiazine.  See  the 
related  editorial:  The  Evolving  Technology  of 
Venous  Access — Wenzel  RP,  Edmond  MB. 
N  Engl  J  Med  1999:340(1  ):48-50. 


590 


Respiratory  Care  •  June  1999  Vol  43  No  6 


AETIFICIA  ,L  k  IRWA .  Yg 


Farf:  I  of  II  Special  Issues 


Presented  by  the  Editorial  Board  of  the 

Respiratory  Care  journal 


Containing  the  manuscripts  and  discussions  from  the  Journal 
Conference  held  December  4-6,  1998,  Cancun,  Mexico 


j^ 


Supported  by  the  American  Association  for  Respiratory  Care 


^M^ffife  faculty  members — front  row,  trom  iert:  Michael )  Bishop  MD,  Maxine  Orringer  MA  CCC-SLP,  Charles  G  Durbin 
Jr  MD.  Charles  B  Watson  MD,  Richard  D  Branson  RRT,  William  E  Hurford  MD.  Second  row.  from  left:  John  L  Stauffer  MD. 
Ann  E  Thompson  MD,  James  K  Stoller  MD,  Ray  Ritz  RRT,  James  F  Reibel  MD,  John  E  Helfner  MD,  Robert  S  Campbell  RR:^ 
Dean  R  Hess  PhD  RRT  FAARC. 


CO-CHAIRS   AND   GUEST   EDITORS 

Richard  D  Branson  RRT — Cincinnati,  Oliio 
and  Charles  G  Durbin  Jr  MD — Charlottesville,  Virginia 


FACULTY 


Michael  J  Bishop  MD 
Seattle,  Washington 

Richard  D  Branson  RRT 
Cincinnati  .Ohio 

Robert  S  Cambell  RRT 
Cincinnati, Ohio 

Charles  G  Durbin  jr  MD 
Charlottesville,  Virginia 

John  E  Heffner  MD 
Charleston,  South  Carolina 


Dean  R  Hess  PhD  RRT  FAARC 

Boston,  Massachusetts 

William  E  Hurford  MD 
Boston,  Massachusetts 

Maxine  Orringer  MA  CCC-SLP 

Pittsburgh,  Pennsylvania 

James  F  Reibel  MD 
Charlottesville,  Virginia 


Ray  Ritz  RRT 
Boston,  Massachusetts 

John  L  Stauffer  MD 
Hershey,  Pennsylvania 

James  K  Stoller  MD 
Cleveland,  Ohio 

Ann  E  Thompson  MD 

Pittsburgh,  Pennsylvania 

Charles  B  Watson  MD 
Bridgeport,  Connecticut 


Conference  Proceedings 


Foreword:  Artificial  Airways 
The  1998  Respiratory  Care  Journal  Conference 


Artificial  airways  play  an  important  role  in  respiratory 
care  practice  and  critical  care  treatment,  but  because  these 
devices  are  universally  employed,  they  are  often  over- 
looked as  a  significant  component  of  care.  Without  artifi- 
cial airways,  mechanical  ventilation  would  be  severely 
hampered.  Over  the  years,  many  innovations  in  airway 
devices  have  been  made,  beginning  with  the  replacement 
of  stiff,  red  rubber  endotracheal  tubes  and  their  noncom- 
pliant  cuffs  with  polyvinyl  chloride  tubes  having  highly 
compliant  cuffs.  The  risks  to  patients  from  the  newer  de- 
vices are  felt  to  be  minimal,  but  this  feeling  is  supported 
by  very  little  evidence  other  than  our  own  empiric  obser- 
vations. A  vast  variety  of  special  purpose  endotracheal 
tubes  and  devices  are  now  available.  The.se  include  tubes 
for  high-frequency  ventilation,  laser  surgery,  and  removal 
of  secretions  above  the  cuff.  These  tubes  have  little  in 
common,  except  that  they  must  adapt  to  common  equip- 
ment connectors.  They  are  used  in  a  wide  range  of  differ- 
ent clinical  situations  to  solve  many  problems. 

In  addition  to  the  devices  themselves,  the  process  and 
practice  of  artificial  airway  placement  are  constantly  un- 
dergoing change.  Many  individuals  and  disciplines  claim  a 
piece  of  this  practice.  Who  should  intubate  and  under  what 
circumstances  have  yet  to  be  determined.  Certainly,  the 
current  practice  suggests  that  the  decision  is,  quite  often,  a 
local  one.  Personnel,  manpower,  and  availability  impact 
the  decision. 

It  is  remarkable  that  many  of  the  innovations  in  airway 
care  (devices  and  methods)  have  not  been  subjected  to 
rigorous  scientific  evaluation.  Airway  management  is  a 
highly  risky  area  of  clinical  practice.  Patient  harm  occurs 
commonly.  Failure  to  place  the  airway  in  a  timely  fashion 
can  result  in  severe  injury.  The  process  of  removing  an 
artificial  airway  also  places  the  patient  at  significant  risk. 

Some  of  the  important  things  we  have  learned  about 
airway  management  and  airway  devices  include: 

1.  Most  often  intubation  is  an  urgent,  not  emergency, 
procedure. 

2.  Simple  means,  ie.  head  position,  manual  ventilation 
skills,  less  invasive  airway  devices  (oropharyngeal 
airways,  nasopharyngeal  airways,  laryngeal  mask  air- 
way), are  most  important  to  well-being  and  survival 
of  the  patient. 


3.  Intubation  success  requires  skill  and  this  is  obtained 
by  frequent  practice. 

4.  The  best  way  to  deal  with  difficult  airways  is  by  a 
preplanned  algorithm. 

5.  The  final  path  of  a  "can't  ventilate,  can't  intubate" 
scenario  in  the  adult  must  include  some  form  of  sur- 
gical approach  to  the  airway. 

6.  After  .securing  an  airway,  proper  care  is  necessary  to 
prevent  additional  patient  harm. 

7.  High  cuff  pressures  are  associated  with  tracheal  in- 
juries, many  of  which  are  reversible. 

8.  Nasal  intubation  is  associated  with  more  complica- 
tions than  oral  intubation. 

But  the  latter  understandings  are  only  a  beginning.  Many 
questions  remain  to  be  answered  in  a  logical  and  scientific 
fashion,  including: 

1.  What  is  an  appropriate  reintubation  rate? 

2.  Following  prolonged  need  for  an  artificial  airway, 
when  is  it  time  to  do  a  tracheostomy? 

3.  Is  percutaneous  dilatational  tracheotomy  (a  new  tech- 
nique) really  a  low-risk  procedure? 

4.  What  are  the  actual  risks  of  laryngeal  and  tracheal 
injury  from  prolonged  intubation  with  the  new  tubes 
and  techniques  for  maintaining  them? 

5.  How  should  we  secure  tubes? 

6.  Should  we  use  minimal  leak  or  minimal  seal  tech- 
niques for  cuff  maintenance? 

7.  What  is  an  acceptable  failure-to-intubate  rate? 

8.  Should  the  acceptable  failure-to-intubate  rate  be  the 
same  in  the  operating  room  as  during  a  cardiac  ar- 
rest? 

9.  What  is  the  "gold  standard"  for  determining  correct 
tube  placement? 

10.  Should  muscle  relaxants  be  used  routinely  as  part  of 
emergency  intubation  attempts? 

1 1 .  How  much  experience  is  required  before  compe- 
tence is  ensured? 

12.  Are  the  same  "standards"  applicable  across  differ- 
ent medical  environments  and  to  different  prac- 
titioners? Clearly  we  have  allowed  the  current 
state  of  the  art  to  develop  without  adequately  an- 
swering these  questions.  Like  many  techniques  in 
medicine,  the  right  answers  probably  change  with 
patient  age  and  diagnosis. 


Respiratory  Care  •  June  1 999  Vol  44  No  6 


593 


Foreword:  Artificial  Airways 

Artificial  airways  is  an  important  area  of  concern  for  and  clinicians  to  the  importance  of  advancing  our  under- 
respiratory  care  practitioners  and  others  interested  in  im-  standing  of  artificial  airways  and  their  management, 
proving  patient  care.  The  conference  papers  presented  in 

this  and  the  next  issue  of  Respiratory  Care  summarize  Charles  G  Durbin  Jr  MD 
our  current  knowledge  and  serve  as  a  starting  point  for  Conference  Co-Chair 
further  investigation.  This  conference  challenged  many  pre- 
conceived notions  about  airway  care,  and  we  anticipate  Richard  D  Branson  RRT 
that  the  following  papers  will  awaken  many  researchers  Conference  Co-Chair 


594  Respiratory  Care  •  June  1999  Vol  44  No  6 


The  History  of  Intubation,  Tracheotomy,  and  Airway  AppHances 


James  K  Stoller  MD 


Introduction 

Historical  Milestones  in  Traclieotomy 
Advances  in  Resuscitation 

Historical  Milestones  in  Airway  Intubation  and  Airway  Appliances 
Continued  Evolution  of  Airway  Tubes  and  Placement  Techniques 
Summary 

[Respir  Care  1999:44(6);595-60l]  Key  words:  histoiy  of  iiitiihcition.  airway 
managemeiu,  resuscitation,  histoiy  of  mechanical  ventilation,  tracheotomy,  tra- 
cheostomy tube. 


Is  it  of  benefit  to  revive  the  knowledge  of  the  past?  In 
unfolding  the  common  patrimony  which  unites  successive 
generations  of  inquiring  men.  in  meeting  them  as  individ- 
uals, in  attempting  to  understand  the  problems  they  had  to 
face,  the  intellectual  climate  in  which  their  investigations 
were  pursued,  and  the  historical  and  social  conditions  un- 
der which  they  lived,  it  is  my  belief  that  a  sharper  con- 
sciousness of  our  own  nature  is  brought  forth.  .  .  . 

— Andre  F  Cournand,  Circulation  of  the  Blood 

Introduction 


This  report  reviews  the  history  of  intubation,  tracheot- 
omy, and  airway  appliances.  After  discussing  historical 
milestones  in  tracheotomy  and  in  the  understanding  of 
respiration  and  vital  gases,  I  review  developments  in  re- 
suscitation that  spurred  new  approaches  to  managing  the 
airway.  The  evolution  of  modern  anesthesia  practice  pro- 
vided a  later  but  very  important  impetus  to  develop  new 
airway  appliances  and  techniques  for  airway  management. 

Historical  Milestones  in  Tracheotomy 


The  history  of  intubation,  tracheotomy,  and  airway  ap- 
pliances weaves  together  developments  in  modem  under- 
standing of  respiration,  the  development  of  resuscitative 
techniques,  and  the  evolution  of  modern  anesthesia  and 
mechanical  ventilation.'-^  Like  most  histories,  this  story 
represents  a  complicated  intertwining  of  developments  in 
separate  lines  of  inquiry  and  is  punctuated  by  some  in- 
sights and  inventions  that  were  marvelously  clever  and 
others  that  appear,  at  least  when  viewed  through  the  mod- 
ern retrospectoscope,  more  naive  and  ill-fated.  Concurrent 
challenges  to  explore  aviation  and  undersea  environments 
provided  venues  to  make  new  discoveries  and  to  test  evolv- 
ing theories  that  accelerated  progress. 


James  K  Sloller  MD  is  affiliated  with  the  Section  of  Respiratory  Therapy. 
Department  of  Pulmonary  and  Critical  Care  Medicine.  The  Cleveland 
Clinic  Foundation.  Cleveland.  Ohio. 

Correspondence:  Jaines  K  Stoller  MD.  Vice-Chairman.  Division  of  Med- 
icine. Head,  Section  of  Respiratory  Therapy.  Department  of  Pulmonary 
and  Critical  Care  Medicine  A90.  The  Cleveland  Clinic  Foundation.  9,'iOO 
Euclid  Avenue.  Cleveland  OH  44195.  E-mail:  stollej@ccf.org. 


The  realization  that  tracheotomy  could  be  used  to  re- 
lieve obstruction  of  the  upper  airway  dates  to  very  early 
times,  with  references  to  this  practice  in  the  ancient  Rig 
Veda  texts  (2000-1500  BC)  and  Eber's  Papyrus  (1550 
BC).  Around  350  BC,  Alexander  the  Great  was  reputed  to 
have  performed  (using  his  sword)  a  tracheotomy  upon  a 
choking  soldier,  and  in  100  BC.  the  first  surgical  perfor- 
mance of  a  tracheostomy  was  attributed  to  the  Greek  phy- 
sician Asclepiades.'  Synthesizing  the  concepts  of  airway 
access  and  artificial  respiration  for  resuscitative  purposes, 
the  Greek  anatomist  Galen  realized  that  tracheotomy  could 
provide  valuable  access.  In  160  AD.  Galen  wrote  "If  you 
take  a  dead  animal  and  blow  air  through  its  larynx  (through 
a  reed),  you  will  fill  its  bronchi  and  watch  its  lungs  attain 
the  greatest  dimension."  This  concept  was  more  fully  de- 
veloped centuries  later  by  the  Flemish  anatomist  Andreas 
Vesalius.""  In  his  book  De  Huniani  Corporis  Fabrica.  pub- 
lished in  1555,  Vesalius  observed: 

But  that  life  may  in  a  manner  of  speaking  be  re- 
stored to  the  animal,  an  opening  inust  be  attempted 
in  the  trunk  of  the  trachea,  into  which  a  tube  of  reed 


Respiratory  Care  •  June  1999  Vol  44  No  6 


595 


The  History  of  Intubation,  Tracheotomy,  and  Airway  Appliances 


or  cane  should  be  put;  you  will  then  blow  into  this, 
so  that  the  lung  may  rise  again  and  the  animal  take 
in  the  air.  Indeed,  with  the  slight  breath  in  the  case 
of  the  living  animal,  the  lung  will  swell  to  the  full 
extent  of  the  thoracic  cavity,  and  the  heart  become 
strong  ...  for  when  the  lung,  long  flaccid,  has  col- 
lapsed, the  beat  of  the  heart  and  arteries  appears 
wavy,  creepy,  twisting;  but  when  the  lung  is  in- 
flated, it  begins  strong  again  ....  And  as  I  do  this, 
and  take  care  that  the  lung  is  inflated  at  intervals, 
the  motion  of  the  heart  and  arteries  does  not  stop. 


For  more  than  a  century  thereafter,  interest  and  knowl- 
edge of  tracheotomy  seemed  to  disappear,  until  an  En- 
glishman named  Robert  Hooke  reproduced  Vesalius's  ex- 
periment. As  described  in  the  second  volume  of  the 
Philosophical  Transactions  of  the  Royal  Society  of  Lon- 
don, on  October  24,  1667,  Hooke  demonstrated  "preserv- 
ing animals  alive  by  blowing  through  their  lungs  with 
bellows. "5  Thereafter,  tracheotomy  seemed  to  disappear 
again  for  over  a  century,  after  which  a  resurgence  of  in- 
terest accompanied  diphtheria  epidemics.  For  example,  in 
1 833  the  renowned  French  physician  Trousseau  reported  a 
series  of  200  tracheotomies  performed  in  diphtheria  pa- 
tients. This  understanding  of  the  value  of  tracheotomy  and 
of  ventilation,  augmented  by  growing  knowledge  and  in- 
terest in  resuscitation,  set  the  stage  for  interest  in  novel 
approaches  to  airway  access,  such  as  intubation  and  air- 
way interfaces.  Thirty-six  years  later,  the  German  surgeon 
Friedrich  Trendelenburg  was  the  first  to  describe  use  of  an 
inflatable  cuff  that  was  fitted  to  a  tracheostomy  tube. '  As 
with  many  concepts  regarding  tracheostomy,  these  insights 
were  later  applied  to  endotracheal  intubation  and  to  endo- 
tracheal tubes. 

Advances  in  Resuscitation 

As  with  the  history  of  airway  techniques  in  general,  the 
history  of  resuscitation  is  closely  intertwined  with  advances 
in  the  understanding  of  vital  gases,  ventilation,  and  tra- 
cheotomy. In  1667  Robert  Hooke  described  using  bellows 
to  ventilate  a  dog  during  a  dissection  and  was  able  to 
maintain  the  heartbeat  for  more  than  an  hour.'  In  a  1669 
study  demonstrating  that  airway  patency  was  important  to 
life,  an  Englishman  named  Richard  Lower  showed  that 
obstruction  of  an  animal's  trachea  by  a  cork  cau.sed  the 
animal's  blood  to  change  color,  which  could  be  restored 
by  removing  the  cork  and  ventilating  the  animal  with  a 
bellows.  This  observation  advanced  the  idea  that  maintain- 
ing the  airway  was  a  priority  to  support  life,  and  provided 
important  background  for  subsequent  studies  by  Joseph 
Priestley,  who,  during  the  1770s  produced  "pure  air,"  and 
of  Antoine  Lavoisier,  who  in  1779  named  oxygen  as  the 


vital  component  of  air,  challenging  the  previously  accepted 
"phlogiston"  theory. 

Interest  in  resuscitation  exploded  in  the  mid-to-late 
1700s,  especially  in  waterside  cities  like  Amsterdam,  Paris, 
London,  Venice,  and  Philadelphia,  where  drownings  were 
common  and  posed  an  obvious  and  serious  challenge  to 
the  citizenry.  The  mid- 1770s  marked  the  first  efforts  to 
resuscitate  the  dead.  For  example,  Tossach  performed  the 
first  known  successful  drowning  resuscitation  using  mouth- 
to-mouth  respiration  in  1740.'  Building  upon  insights  from 
earlier  studies  by  Galen  and  Vesalius,  Buchan  advocated 
"creating  an  opening  in  the  windpipe  when  air  could  not 
be  insufflated  via  mouth  or  nose."  In  1 740,  the  Academy 
of  Sciences  in  Paris  advocated  mouth-to-mouth  resuscita- 
tion for  drowning  victims.  Soon  thereafter,  in  1767,  the 
Dutch  Society  for  Rescue  of  Drowned  Persons  developed 
principles  of  resuscitation,  which  included  5  key  steps, 
some  of  which  still  abide,  and  others  of  which  are  viewed 
comically  in  retrospect.  The  steps  included:  (1)  warm  the 
victim,  (2)  provide  artificial  ventilation  through  the  mouth, 
(3)  provide  rectal  insufflation  of  tobacco  smoke,  (4)  blood- 
let,  and  (5)  provide  a  stimulant,  either  orally  or  rectally. 
Further  advances  were  encouraged  by  competitions  to  de- 
velop resuscitation  aids,  which  were  sponsored  by  the  Royal 
Humane  Society  (formed  in  England  in  1774)  and  by  the 
formation  of  similar  societies  in  other  cities  (eg,  Venice 
and  Philadelphia).  Such  competitions  engendered  a  variety 
of  new  approaches,  such  as  use  of  a  bellows  for  drowning 
resuscitations,  use  of  a  double  bellows  (by  Hunter  in  1 776) 
that  would  deliver  air  with  one  stroke  and  withdraw  ex- 
haled gas  on  the  second  stroke,  and  the  use  (by  Chaussier 
in  1780)  of  a  bag-face  mask  system  with  oxygen  bleed-in.' 
These  progressive  trends  in  development  of  resuscitative 
and  airway  techniques  were,  unfortunately,  derailed  in  the 
1820s,  when  observations  emerged  that  bellows  inflation 
of  the  lungs  could  lead  to  fatal  pneumothorax.  Such  ad- 
verse outcomes  prompted  the  Royal  Humane  Society  to 
condemn  positive  pressure  techniques  in  c.  1 827,  diverting 
attention  away  from  positive  pressure  ventilatory  tech- 
niques and  prompfing  attention  to  negative  ventilation 
techniques.  Significant  progress  in  negative  ventilatory 
techniques  was  made  between  1832,  when  a  Scotsman 
named  Dalziel  developed  the  first  tank  ventilator,  con- 
sisting of  an  air-tight  box  with  a  neck  collar  and  bellows 
with  a  one-way  valve,  and  1928,  when  Drinker  and 
Shaw  developed  the  "iron  lung,"  which  in  some  ways 
diverted  interest  from  airway  appliances  and  techniques. 
However,  interest  in  resuscitation  had  engendered  new 
ideas  about  airway  management  and  airway  appliances 
that  would  later  prove  useful  when  interest  in  positive 
pressure  ventilatory  techniques  for  surgery  and  anes- 
thetic management  reemerged. 


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Historical  Milestones  in  Airway  Intubation  and 
Airway  Appliances 

Though  the  concept  of  tracheotomy  had  been  well  es- 
tablished since  ancient  times,  interest  in  intubating  rather 
than  incising  the  airway  was  an  outgrowth  of  resuscitative 
efforts  that  sought  to  preserve  the  victim's  life.  For  exam- 
ple, Cullen  first  suggested  tracheal  intubation  for  reviving 
the  dead  in  1776,  and  15  years  later  devised  an  intra- 
laryngeal  cannula  for  placement  during  resuscitation.  Be- 
tween 1791  and  1800,  Curry,  and  then  Fine,  proposed 
other  intralaryngeal  cannula  for  artificial  resuscitation  that 
could  be  placed  via  the  nose,  mouth,  or  trachea.  After 
unsuccessful  efforts  by  Bouchut  in  1858  to  relieve  diph- 
theritic upper  airway  obstruction,  William  MacEwen  at  the 
Glasgow  Royal  Infirmary  reported  the  first  successful  re- 
lief of  upper  airway  obstruction  by  means  of  intubation.*^ 
Specifically,  in  the  July  24,  1880  volume  of  the  British 
Medical  Journal,  MacEwen  reported  on  3  patients  who 
were  intubated  for  management  of  their  conditions.  Mac- 
Ewen introduced  "into  the  trachea  by  way  of  the  mouth,  a 
tube,  which  would  extend  beyond  the  vocal  cords,  and 
through  which  the  patient  would  respire.  The  upper  laryn- 
geal opening  could  then  be  plugged  outside  this  tube  so  as 
to  prevent  the  entrance  of  blood  into  the  larynx."  In  2  of 
the  patients,  the  intubation  was  performed  to  relieve  diph- 
theritic upper  airway  obstruction.  In  the  third  patient,  the 
intubation  was  performed  to  permit  a  surgical  resection  of 
"an  epithelioma  from  the  pharynx  and  base  of  the  tongue." 
Following  MacEwen' s  seminal  report,  interest  in  intuba- 
tion for  surgery  grew,  and  John  O'Dwyer  of  New  York 
presented  a  report  in  the  August  8,  1885,  volume  of  the 
New  York  Medical  Journal  in  which  he  described  an  en- 
dotracheal tube  and  instruments  for  its  placement  and  re- 
moval, thereby  reproducing  MacEwen' s  experience  from 
5  years  earlier.^  In  1887,  George  Fell,  Professor  of  Phys- 
iology and  Microscopy  at  Niagara  University  in  Buffalo, 
described  a  system  in  which  a  bellows  was  attached  to  the 
endotracheal  tube  for  the  purpose  of  providing  positive 
pressure  ventilation  to  a  patient  experiencing  ventilatory 
failure  from  an  opiate  overdose."*  (Fig.  1)  Fell  described  5 
elements  of  the  system: 

1 .  an  air- forcing  apparatus  like  an  ordinary  bellows, 

2.  a  tracheal  tube  which  could  be  left  in  the  trachea  for 
24  hours  or  more,  and  which  was  filled  with  annular 
corrugations, 

3.  a  valve  between  the  bellows  and  the  lung, 

4.  a  rubber  adapter  between  the  tracheal  tube  and  the 
bellows  "to  prevent  the  movements  of  the  patient 
from  disarranging  the  tube  in  the  trachea,"  and 

5.  a  movable  piece  on  the  tracheal  tube  to  allow  re- 
moval and  reattachment  of  the  tubing  to  the  bellows. 

With  such  a  device.  Fell  concluded  "I  believe  it  possible 
for  the  practitioner,  without  an  assistant,  to  make  the  entire 


Fig.  1 .  Device  for  delivering  anesthesia  and  positive  pressure  ven- 
tilation, using  a  bellows.  The  device  was  developed  by  George  Fell 
and  John  O'Dwyer,  with  subsequent  modification  by  Rudolph  Ma- 
tas  in  1900.  (From  Reference  9,  with  permission.) 


operation  and  resuscitate  a  patient  in  ...  a  perilous  con- 
dition." Concurrent  interest  in  thoracic  surgical  techniques 
(including  the  first  description  of  the  median  sternotomy, 
called  the  "median  normal  thoracic  incision"  by  Milton  in 
1897)  provided  an  impetus  to  apply  these  strides  in  airway 
management  and  positive  pressure  ventilation  to  chest  sur- 
gery. Specifically,  in  1900,  Rudolph  Matas,  from  New 
OHeans,  described  an  adaptation  of  the  O'Dwyer-Fell  bel- 
lows-laryngeal  cannula  system  for  the  purpose  of  admin- 
istering intralaryngeal  anesthesia.'  Recognizing  that  the 
O'Dwyer-Fell  apparatus  made  "no  provision  for  the  main- 
tenance of  anesthesia  while  artificial  respiration  was  being 
applied,"  Matas  "altered  the  laryngeal  cannula  by  furnish- 
ing a  branch  and  a  stopcock,  which  are  connected  to  a 
rubber  tube  and  funnel,"  (Fig.  2)  thereby  permitting  the 
administration  of  anesthetics  directly  into  the  larynx  to 
maintain  anesthesia. 

After  MacEwen's  introduction  of  the  endotracheal  tube 
in  1880,  different  strategies  were  explored  for  administer- 
ing air  and  gas  through  the  endotracheal.  Specifically,  the 
technique  espoused  by  MacEwen,  O'Dwyer,  and  others 
employed  a  wide  caliber  endotracheal  tube  through  which 
gas  was  introduced  into  the  lung  and  through  which  ex- 
haled gases  exited  the  lung.  This  technique  was  called 
"inhalational  endotracheal  anaesthesia."  An  alternative 
strategy,  called  "insufflation,"  was  first  advocated  by  Bar- 


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The  History  of  Intubation,  Tracheotomy,  and  Airway  Appliances 


Fig.  2.  Device  that  allowed  delivery  of  anesthetic  agents  to  intu- 
bated patients,  as  proposed  by  Mates.  The  stopcock  controls  the 
supply  of  anesthetic  agent  w/ithout  interrupting  air  flow  from  the 
bellows.  Original  figure  text  read  "The  author's  modification  of 
G'Dwyer's  intubating  apparatus  for  surgical  cases  in  which  artifi- 
cial respiration  or  pulmonary  insufflation  may  be  required  with 
anesthesia.  The  stopcock  controls  the  supply  of  the  anesthetic 
without  interfering  with  the  passage  of  air  furnished  by  the  bellows 
or  air  pump."  (From  Reference  9,  with  permission.) 


thelemy  and  Dufour  in  1907,'"  and  more  fully  developed 
by  Melzer  and  Auer  in  1909."  It  involved  use  of  a  narrow 
caliber  tube  in  the  trachea,  through  which  gas  was  intro- 
duced into  the  lung;  gas  exiting  the  lung  passed  between 
the  outside  of  the  tube  and  the  tracheal  wall  (ie,  outside  the 
endotracheal  tube).  Insufflation  remained  a  popular  strat- 
egy for  approximately  a  decade  thereafter,  after  which 
enthusiasm  waned  under  the  weight  of  several  important 
observations  and  developments.  First,  increasing  attention 
was  being  given  to  the  hazards  of  aspiration,  as  amply 
demonstrated  in  a  paper  by  Chevalier  Jackson  of  Pitts- 
burgh in  1911:  "When  tracheal  and  bronchial  secretions 
are  in  excess  of  the  amount  required  properly  to  moisten 
the  inspired  air,  they  become  a  menace  to  life  unless  re- 
moved."'- Clearly,  the  insufflation  technique  afforded  no 
protection  against  aspiration.  Second,  as  expensive  inha- 
lational  anesthetic  agents  like  nitrous  oxide  gained  ascen- 
dancy in  anesthetic  practice,  it  became  apparent  that  in- 
sufflation was  impractically  wasteful.  Thus,  by  World  War 
I,  insufflation  had  largely  faded  from  practice,  and  most 
subsequent  developments  were  rooted  in  the  technique 
called  "inhalational  endotracheal  anesthesia." 

Continued  Evolution  of  Airway  Tubes  and 
Placement  Techniques 

With  the  establishment  of  endotracheal  intubation  as  the 
preferred  technique,  the  weight  of  attention  given  endo- 
tracheal intubation  spawned  further  innovation  in  the  tubes 
themselves,  as  well  as  techniques  for  tube  placement  into 
the  airway.  As  discus.sed  below,  some  of  these  innovations 


Fig.  3.  Laryngoscope  as  introduced  by  Jackson,  c  1913.  Original 
figure  text  read  "Schema  illustrating  the  direction  of  motion  to  be 
imparted  to  the  laryngeal  speculum  in  exposure  of  the  larynx  for 
the  introduction  of  ether  insufflation  tubes."  (From  Reference  12, 
with  permission.) 


have  claimed  places  in  modern  anesthesia  practice,  includ- 
ing: the  use  of  special  forceps  to  facilitate  tube  placement; 
the  use  of  cricoid  pressure  to  avert  aspiration  or  gastric 
insufflation  during  intubation;  topical  anesthesia  of  the 
airway  before  intubation;  modification  of  the  tubes  to  fa- 
cilitate suctioning  and  prevent  occlusion  by  the  patient's 
secretions;  use  of  low  pressure,  high  compliance  cuff  bal- 
loons; and  use  of  a  pilot  balloon  to  indicate  the  pressure  in 
the  cuff  balloon. 

With  regard  to  tube  placement,  by  1930  the  hard  endo- 
tracheal tubes  originally  described  by  MacEwen  and 
O'Dwyer  had  been  supplanted  by  rubber  catheters,  which 
could  be  placed  either  orally  or  nasally.  Blind  nasal  intu- 
bation was  described  in  1930  by  Magill"'-*  as  a  useful 
technique  for  intra-oral  operations,  along  with  other  ad- 
vantages that:  (1)  "it  can  be  carried  out  under  light  anes- 
thesia without  muscular  relaxation,  and  (2)  there  is  no  risk 
of  damage  to  teeth  or  growths  by  the  speculum."  The 
laryngoscope  had  been  introduced  in  1913  by  Chevalier 
Jackson  (Fig.  3).  and  was  in  widespread  use  (Fig.  4).  How- 
ever, to  facilitate  tube  placement.  Magill  described  a  for- 
ceps (which  still  carries  his  name)  and  "a  method  of  pass- 
ing rubber  tubes  and  catheters  into  the  trachea  by  picking 
up  the  ends  in  the  pharynx  with  the  aid  of  a  forceps  and 
direct  vision  laryngoscope." 

The  hazards  of  aspiration  had  been  recognized  since  the 
time  of  MacEwen's  original  description  of  the  endotra- 
cheal tube.  Indeed,  in  his  description  of  the  case  in  which 
an  endotracheal  tube  was  used  to  facilitate  resection  of  a 
pharyngeal  "epithelioma,"  MacEwen  states: 

As  it  was  an  operation  which  would  cause  consid- 
erable bleeding,  precautions  had  to  be  taken  to  se- 
cure the  air  passages  from  occlusion.  Hitherto  this 


598 


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The  History  of  Intubation,  Tracheotomy,  and  Airway  Appliances 


9 1  i^^^HBfl&fi  ^|^^B|^H^H^^Jv^       /^^ 


Fig.  4.  Early  technique  for  intubation  using  a  laryngoscope.  Orig- 
inal figure  text  read  "[Left]  Photograph  of  patient  with  head  upon 
a  pillow,  the  head  flexed.  In  this  position  it  is  easy  to  examine  the 
larynx  with  the  laryngeal  speculum  for  diagnosis,  but  the  larynx  will 
not  be  exposed  in  a  line  with  the  tracheal  axis  so  that  this  position 
is  not  adapted  to  the  passing  of  tubes  through  the  speculum. 
[Center]  The  pillow  is  removed,  the  head  is  flat  on  the  table  and  the 
anaesthetist  is  beginning  to  force  the  head  into  an  extended  po- 
sition. The  thumbs  are  on  the  forehead  and  the  fingers  are  at  the 
side  of  the  head.  The  direction  of  motion  is  shown  by  the  dart 
[arrow].  [Right]  The  anaesthetist  is  lifting  with  the  tip  of  the  specu- 
lum in  the  direction  of  the  dart.  The  speculum  is  always  held  in  the 
left  hand.  The  right  hand,  of  which  the  index  has  been  protecting 
the  upper  lip,  has  now  received  the  catheter  from  the  nurse." 
(From  Reference  12,  with  permission.) 


had  been  effected  by  opening  the  windpipe,  by  la- 
ryngotomy,  and  the  introduction  of  Trendelenburg's 
tampon-cannula.  Instead  of  this,  I  had  determined 
should  an  opportunity  present,  to  introduce  into  the 
trachea,  by  way  of  the  mouth,  a  tube  which  would 
extend  beyond  the  vocal  cords,  and  through  which 
the  patient  would  respire.  The  upper  laryngeal  open- 
ing could  then  be  plugged  outside  this  tube  so  as  to 
prevent  entrance  of  blood  into  the  larynx."* 


In  1946  Mendelson  described  the  syndrome  (which  bears 
his  name)  of  massive  maternal  aspiration  accompanying 
childbirth,  and  within  5  years  thereafter,  several  strategies 
to  lessen  the  risk  of  aspiration  had  been  reported. '^  Spe- 
cifically, Morton  and  Wylie  described  rapid  sequence  in- 
tubation of  the  seated  patient  using  barbiturate,  muscle 
relaxant,  and  prompt  airway  management.'*  Later  citing 
the  disadvantages  of  the  approach  proposed  by  Morton 
and  Wylie,  namely  that: 

1.  rapid  induction  of  anaesthesia  in  the  sitting  po- 
sition predisposes  to  cardiovascular  collapse  in 
the  patient  who  is  seriously  ill,  and 

2.  the  sitting  position  is  not  protection  if  active 
vomiting  takes  place  in  the  brief  interval  be- 
tween loss  of  consciousness  and  onset  of  mus- 
cular relaxation. 


tion  of  stomach  or  esophageal  contents  during  induction  of 
anesthesia,  or  (b)  to  prevent  gastric  distention  from  posi- 
tive pressure  ventilation  applied  by  facepiece  or  mouth- 
to-mouth  respiration.  It  is  contraindicated  during  active 
vomiting."''' 

Along  with  the  realization  that  aspiration  of  blood  and/or 
gastric  contents  into  the  trachea  was  undesirable,  so  too 
had  it  become  apparent  that  accumulation  of  the  patient's 
own  secretions  within  the  lung  and/or  central  airways  posed 
an  important  threat  to  recovery.  In  this  context,  it  became 
clear  that  the  endotracheal  tube  was  not  only  a  conduit  for 
insufflating  gas  into  the  lung,  but  also  a  conduit  for  the 
removal  of  secretions  from  the  lung.  In  1911,  Jackson 
described  2  cases  and  cited  10  others  from  his  practice  in 
which  the  patient's  own  secretions  posed  a  grave  threat.  In 
a  1911  editorial  entitled  "The  drowning  of  the  patient 
in  his  own  secretion,"'*  Jackson  advocated  the  role  of 
bronchoscopy  as  a  technique  for  bronchial  toilet.  In  his 
1938  review  of  "Intratracheal  suction  in  the  management 
of  postoperative  pulmonary  complications,"  Haight  pro- 
posed suctioning  with  a  catheter  passed  into  the  patient's 
airway  as  a  more  available  alternative  to  bronchoscopy. 
Specifically, 

Attention  will  be  particularly  called  to  intratracheal 
suction  by  means  of  a  catheter  introduced  through 
the  nares.  Its  purpose  is  the  same  as  bronchoscopic 
aspiration,  and  it  may  be  used  either  in  preference 
to  bronchoscopy,  to  supplement  bronchoscopy  when 
repeated  aspirations  are  necessary,  or  as  an  alterna- 
tive to  bronchoscopy  when  the  latter  is  not  avail- 
able. 

The  specific  technique  involved  passing  a  16  French 
soft  rubber  urethral  catheter'''  or  a  Robinson  urethral  cath- 
eter (which  had  a  double  instead  of  a  single  opening) 
through  the  nares  and  into  the  larynx,  and  then  attaching 
the  tubing  to  a  suction  machine.  In  prescient  anticipation 
of  the  ongoing  current  debate  about  the  preferred  method 
to  treat  established  atelectasis,  Haight  noted  that  "it  is 
impossible  to  be  dogmatic  about  the  relative  indications 
for  bronchoscopic  aspiration  or  aspiration  with  an  intra- 
tracheal catheter.  Both  methods  have  a  place.  Frequently 
they  can  be  used  interchangeably  and  it  is  often  a  matter  of 
election  as  to  which  should  be  used."-"  Finally,  Haight 
also  painted  out  the  value  of  intraoperative  suctioning  to 
avert  postoperative  complications  of  atelectasis.  He  wrote 
that 


Sellick,  from  the  Middlesex  Hospital,  proposed  the  tech- 
nique of  cricoid  pressure  in  1961.  Citing  success  in  23  of 
26  high-risk  cases,  Sellick  concluded  "Backward  pressure 
of  the  cricoid  cartilage  against  the  cervical  vertebrae  can 
be  used  to  occlude  the  esophagus  (a)  to  control  regurgita- 


Should  it  be  known  that  numerous  secretions  are 
being  aspirated  into  the  trachea  during  the  opera- 
tion, it  may  be  advisable  for  the  anesthetist  to  insert 
a  large  intratracheal  catheter  and  to  administer  the 
anesthetic  agent  through  this  catheter.  Periodic  as- 
pirations by  the  insertion  of  a  smaller  catheter 


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The  History  of  Intubation,  Tracheotomy,  and  Airway  Appliances 


through  the  larger  one  can  then  be  carried  out  dur- 
ing the  course  of  the  operation. 


Murphy,  in  a  1941  report  considering  the  ideal  charac- 
teristics of  an  intratracheal  catheter,  articulated  9  desiderata: 

1.  Sufficient  flexibility  to  accommodate  itself  to 
the  pharynx  and  larynx, 

2.  Sufficient  elasticity  to  prevent  irritation  to  the 
parts  through  which  it  passes, 

3.  Sufficient  body  to  resist  the  compression  to  which 
it  would  ordinarily  be  subjected  when  in  use, 

4.  Resistance  to  kinking  when  bent  at  a  moderately 
acute  angle, 

5.  Ease  of  sterilization,  preferably  by  heat, 

6.  Durability  in  spite  of  repeat  sterilizations, 

7.  Ease  on  insertion. 

8.  Adequate  diameter  of  lumen  in  relation  to  out- 
side diameter,  and 

9.  Availability  in  a  sufficient  range  of  sizes.-' 


Murphy  also  considered  the  challenges  of  aspirating  se- 
cretions through  the  endotracheal  tube,  and  proposed  a 
new  catheter  design  that  incorporated  two  distal  sideholes 
or  lateral  eyes,  the  importance  of  which  were  that  "should 
one  or  more  of  the  eyes  become  obstructed  by  mucus, 
breathing  is  still  not  embarrassed."  These  "Murphy  eyes" 
remain  a  standard  feature  of  modern  endotracheal  tubes. 

Local  application  of  cocaine  to  the  airway  before  intu- 
bation was  a  technique  introduced  by  Rosenberg  in  1 895,-- 
and  later  advocated  by  Magill.'"*-^  Citing  the  advantages 
of:  (1)  easier  induction,  (2)  the  possibility  of  intubation 
without  necessity  of  deep  anesthesia,  (3)  diminution  of  the 
cough  reflex,  permitting  a  light  maintenance  level,  and  (4) 
less  frequent  post-anesthetic  sore  throat,  Magill  recom- 
mended using  "an  infinitesimal  quantity  of  a  20%  solution 
from  a  nebulizer." 

In  1 869  Trendelenburg  was  first  to  propose  a  cuff  for  a 
tracheostomy  tube  (the  so-called  "tampon-cannula").'-^  In 
1906  Green  described  a  pilot  balloon  for  the  purpose  of 
inflating  the  cuff  and  monitoring  the  pressure  within  the 
cuff  balloon. 24  Like  many  innovations  in  airway  manage- 
ment, the  idea  lay  fallow  for  a  time.  The  pilot  balloon 
concept  was  adopted  and  republished  by  Hewer  37  years 
later.-* 

Along  with  the  concept  of  the  Murphy  eye  and  the  pilot 
balloon,  modern  tracheotomy  and  endotracheal  tubes  in- 
clude a  cuff  to  avert  aspiration  and  to  enhance  ventilation. 
In  the  early  1970s,  attention  was  directed  to  the  hazards  of 
tracheal  mucosal  damage  from  high  pressure  cuffs.  Vari- 
ous remedial  strategies  had  been  examined,  including  us- 
ing double-cuffed  tubes,  cylindrical  tubes,  spacers  to  vary 
the  level  of  tracheal  contact,  flange  seals  (instead  of  cuffs), 
and  intermittent  cuff  inflation  to  coincide  with  ventilator 
inflation.-''  By  1971  the  remaining  and  now  time-honored 


strategy  of  low  pressure,  high  compliance  cuffs  had  been 
proposed  and  studied  in  a  landmark  randomized  controlled 
trial  conducted  by  Grillo  et  al.-''  The  study  involved  90 
patients  undergoing  tracheostomy  at  the  Massachusetts 
General  Hospital,  of  whom  45  were  deemed  eligible  and 
randomly  allocated  to  use  of  the  standard,  high  pressure 
Rusch  tube,  versus  a  new  latex,  high  compliance,  low 
pressure  tube.  As  soon  as  each  patient  was  able  to  tolerate 
a  5-10  minute  period  of  ventilator  independence  (after  a 
mean  duration  of  ventilation  of  17-18  days),  the  trache- 
ostomy tube  was  removed  and  the  trachea  was  examined 
with  a  right  angle  telescope  for  mucosal  damage,  which 
was  graded  on  a  0-4  ordinal  score  (where  higher  scores 
denoted  more  severe  mucosal  damage).  The  final  grades 
were  the  mean  of  2  scores  independently  graded  by  2 
examiners,  at  least  1  of  whom  was  blinded  to  the  type  of 
cuff.  The  study  results  showed  less  frequent  and  less  se- 
vere tracheal  mucosal  damage  with  the  high  compliance, 
low  pressure  cuffs.  Specifically,  the  mean  tracheal  damage 
score  with  the  standard  cuff  was  2.6,  versus  1 .3  with  the 
new  cuff  (p  <  0.001 ),  and  68%  of  new  cuff  users  received 
a  grade  below  2,  versus  none  of  the  standard  cuff  users. 
This  study,  which  was  extraordinary  for  both  its  clinical 
elegance  and  its  use  of  a  rigorous,  randomized  trial  archi- 
tecture, concluded  that  "the  new  soft  cuff  for  tracheostomy 
tubes  minimizes  tracheal  injury  and  should  reduce  the  oc- 
currence of  tracheal  stenosis  and  other  damage  caused  by 
pressure  necrosis  at  the  cuff  site."  The  findings  from  this 
randoiTiized  trial  represented  a  major  advance  and  ushered 
in  the  modern  era  in  which  such  soft  cuffs  are  used  rou- 
tinely. 

The  role  of  low  pressure  cuffs  was  further  buttressed  by 
later  reports  suggesting  that  the  transition  from  high  to  low 
pressure  cuffs  was  associated  with  a  lower  frequency  of 
severe  tracheal  complications.  For  example,  in  1978  Lewis 
et  al  presented  a  study  comparing  the  frequency  of  severe 
tracheal  complications  in  ventilated  patients  using  high 
pressure  cuffs  (1970  through  early  1972)  versus  low  pres- 
sure cuffs  (late  1972  through  1975).-"  Despite  an  increase 
in  the  number  of  ventilated  patients  (from  403  to  747) 
during  the  later  interval,  and  a  longer  mean  duration  of 
ventilation  (from  3.9  to  6.0  days),  the  frequency  of  severe 
tracheal  complications  (eg,  stenosis  and  tracheo-innomi- 
nate  artery  fistula)  decreased  significantly  (from  2.7%  to 
0.3%,  p  <  0.005)  as  did  the  frequency  of  deaths  due  to 
severe  tracheal  complications  (from  1.7%  to  0.1%,  p  < 
0.01).  Taken  together  with  the  earlier  results,-''  these  clin- 
ical observations  have  secured  the  place  of  low  pressure, 
high  compliance  cuffs  in  current  practice. 

Finally,  a  more  recent  advance  in  the  development  of 
airway  appliances  has  been  the  introduction  of  double  lu- 
men endotracheal  tubes.  The  earliest  versions  of  such  tubes, 
such  as  the  Carlens^'  and  the  Robertshaw  tubes,^^  were 
based  on  a  double  lumen  bronchoscope  with  inflatable 


600 


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The  History  of  Intubation,  Tracheotomy,  and  Airway  Appliances 


cuffs  that  was  first  used  in  1934  to  perform  bronciiospi- 
rometry.  Bronchospirometry  was  an  early  procedure  to 
evaluate  the  function  of  each  lung  separately,  for  example, 
in  assessing  the  patient's  candidacy  for  lung  resection.-^  Six 
years  later,  Zavod  described  the  first  double  lumen  catheter 
for  bronchospirometry,  setting  the  stage  for  Carlens"s  intro- 
duction of  a  modified  double  lumen  catheter  in  1940. 

In  1950  Bjork  and  Carlens  reported  using  this  double 
lumen  bronchospirometry  catheter  to  prevent  lung  soilage 
during  20  resections  of  infected  lung  segments.-^  As  ex- 
perience with  double  lumen  endotracheal  tubes  increased, 
the  appreciation  of  design  shortcomings  (eg,  that  presence 
of  the  carinal  hook  on  the  Carlens  tube  made  placement 
difficult,  and  that  the  lumina  were  small,  precluding  suc- 
tioning) encouraged  further  modification. 

In  1962  Frank  Robertshaw  described  a  new  tube  (that 
bears  his  name),-**  featuring  the  absence  of  a  carinal  hook, 
and  larger  lumina  than  the  Carlens  tube.  Newer  versions  of 
double  lumen  tubes  continue  to  develop  these  desirable 
features  of  easy  placement  and  large  lumina  to  permit 
secretion  removal. 

Summary 

In  summary,  substantial  advances  in  airway  manage- 
ment and  airway  appliances  have  been  made  since  early 
times  when  soldiers  underwent  tracheotomy  by  sword  and 
animals  were  revived  by  introducing  reeds  into  the  tra- 
chea. This  progress  derived  from  interwoven  advances  in 
resuscitation,  ventilation,  and  airway  management,  and  re- 
flects the  efforts  of  thoughtful  and  persistent  clinicians 
seeking  better  ways  to  address  their  patients'  respiratory 
care  needs. 


REFERENCES 

Colice  GL.  Historical  perspective  on  the  development  of  mechanical 

ventilation.  In:  Principles  and  practice  of  mechanical  ventilation. 

Tobin  MJ.  editor.  New  York:  McGraw-Hill:  I994:l-3.'i. 

Hewer  CL.  Recent  advances  in  anesthesia  and  analgesia.  4th  edition. 

(publisher  unknown):  London:  1943:11.'). 

Gillespie  NA.  The  evolution  of  endotracheal  anaesthesia.  J  Hist  Med 

1946;1:583-594. 


10. 

II. 

12. 

13. 

14. 

15. 

16. 

17. 

IX. 

19. 

20. 

21. 

22. 
23. 

24. 
25. 

26. 

27. 
28. 


Vesalius  A.  De  Humani  Corporis  Fabrica  1543:662. 
Hooke  R.  [title  unknown.]  Phil  Trans  Roy  Soc  1667;2:539. 
MacEwen  W.  Clinical  observations  on  the  introduction  of  tracheal 
tubes  by  the  mouth  instead  of  performing  tracheostomy  or  laryngot- 
omy.  Br  Med  J  1880;2:122-124,  163-165. 
O'Dwyer  J.  Intubation  of  the  larynx.  N  Y  Med  J  1 885:4:145. 
Fell  GE.  Forced  respiration  in  opium  poisoning  -  its  possibilities  and 
the  apparatus  best  adapted  to  produce  it.  Buffalo  Med  Surg  J  1887; 
28:145. 

Matas  R.  Intralaryngeal  insufflation  for  the  relief  of  acute  surgical 
pneumothorax:  its  history  and  methods  with  a  description  of  the 
latest  devices  for  this  purpose.  JAMA  1900;34:1468-1473. 
Barthelemy.  Dafour.  [author's  initials  and  title  unknown.)  La  Presse 
Medicale  1907:15:475. 
Mclzer  SJ.  Auer  J.  J  Exp  Med  1 909;  1 1:622. 

Jackson  C.  The  technique  of  insertion  of  intratracheal  insufllation 
tubes.  Surg  Gynecol  Obstet  1913;17:507-509. 
Magill   IW.   Endotracheal   anaesthesia.   Proc   R   Soc   Med    1928; 
22:8.3-88. 

Magill  IW.  Technique  in  endotracheal  anaesthesia.  BMJ  I9.30;2: 
817-819. 

Mendelson  CL.  The  aspiration  of  stomach  contents  into  the  lungs 
during  obstetric  anesthesia.  Am  J  Obstet  Gynecol  1946:52: 191-205. 
Morton  HJV.  Wylie  WD.  Anaesthetic  deaths  due  to  regurgitation  or 
vomiting.  Anaesthesia  1951;6:190-205. 

Sellick  BA.  Cricoid  pressure  to  control  regurgitation  of  stomach 
contents  during  induction  of  anaesthesia.  Lancet  1961:2:404^06. 
Jackson  C.  The  drowning  of  the  patient  in  his  own  secretion.  La- 
ryngoscope 191  1:21:1  18.V!  185. 

Chardon  L.  Tracheobronchial  aspiration  with  a  urethral  catheter. 
JAMA  1950:142:10.39-1044. 

Haight  C.  Intratracheal  suction  in  the  management  of  postoperative 
pulmonary  complications.  Ann  Surg  1938:107:218-228. 
Murphy  FJ.  Two  improved  intratracheal  catheters.  Anesth  Analg 
1941:27:102-105. 

Rosenberg.  Berl  klin  Wochen.schr.  1895;  i  and  ii. 
Mclntyre  JWR.  History  of  anaesthesia:  oropharyngeal  and  nasopharyn- 
geal airways:  I  (1880  -  1995).  Can  J  Anaesth  1996;43(6):629-635. 
Green  NW.  [title  unknown]  Surg  Gynecol  Obstet  I906;2:512. 
Grillo  HC.  Cooper  JD.  Geffin  B,  Pontoppidan  H.  A  low  pressure  cuff 
for  tracheostomy  tubes  to  minimize  tracheal  injury.  A  comparative 
clinical  trial.  J  Thorac  Cardiovasc  Surg  1971:62(6):898-907. 
Lewis  FR  Jr.  Schlobohm  RM.  Thomas  AN.  Prevention  of  compli- 
cations from  prolonged  tracheal  intubation.  Am  J  Surg  1978:135(3): 
452-457. 

Bjork  VO.  Carlens  E.  The  prevention  of  spread  during  pulmonary 
resection  by  the  use  of  a  double  lumen  catheter.  J  Thorac  Surg 
1950:20:151-157. 

Robertshaw  FL.  Low  resistance  double-lumen  endotracheal  tubes. 
Brit  J  Anaesth  1962:,34:576-579. 


Discussion 

Bishop:  That  was  terrific.  I  really 
enjoyed  that.  One  person  that  you 
didn't  refer  to  was  Desault.  The  first 
slide  I  am  going  to  show  tomorrow 
credits  him  with  the  first  modern  de- 
scription of  tracheal  intubation,' 
early  in  the  19th  century.  What's  in- 


teresting about  Desault' s  description 
is  that  he  was  actually  trying  to  place 
a  feeding  tube,  not  to  intubate  the 
larynx.  While  he's  often  credited 
with  the  first  modern  description  of 
tracheal  intubation,  he's  not  often 
credited  with  the  first  placement  of 
a  feeding  tube  in  the  trachea.  He  then 
delivered  some  bouillon  down  it  and 


the  patient  coughed.  I  guess  he  said 
"Voila!"  and  published  it.  but  the 
technique  really  didn't  get  popular- 
ized, and  tracheotomy,  as  you  de- 
scribed, became  the  treatment  advo- 
cated for  diphtheria  as  tracheal 
intubation  came  into  disfavor  and 
eventually  was  condemned  by  the 
Paris  academy,  as  you  mentioned. 


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The  History  of  Intubation,  Tracheotomy,  and  Airway  Appliances 


REFERENCE 

I .  Albert!  PW.  Tracheotomy  versus  intuba- 
tion: a  19th  century  controversy.  Ann  Otol 
Rhino!  Laryngol  I984;93{4  Pt  1):333- 
337. 

Stoller:  Well,  I  appreciate  that.  Your 
comment  highlights  a  problem  that  I 
encountered  in  looking  through  this 
historical  literature.  One  of  the  con- 
cerns in  giving  a  talk  like  this  is  that 
important  developments  might  have 
escaped  the  attention  of  some  histori- 
ans. It  wouldn't  surprise  me  if  there 
are  more  examples  (perhaps  less  well 
cited  than  even  this)  of  major  devel- 
opments that  have  escaped  current  at- 
tention because  there  was  no  mecha- 
nism at  that  time  for  promulgating 
developments  to  a  wide  audience.  I 
think  we  should  appreciate  that  one  of 
the  historical  aspects  of  the  present 
meeting  is  the  fact  that  this  type  of 
meeting,  this  communication  mecha- 
nism, is  itself  a  medical  evolution  and 
a  medical  development  that  will  help 
to  transcend  the  research  challenges  I 
encountered  in  writing  this  history,  and 
that  you've  appropriately  cited  in  my 
missing  one  of  the  important  develop- 
ments. 

Bishop:  I  think  there  was  a  prize  of- 
fered by  Napoleon  III  for  the  greatest 
advance  in  the  treatment  of  diphthe- 
ria— and  that  prize  went  for  trache- 
otomy. 

Stoller:    Yes. 

Stauffer:  One  comment  and  one 
question.  The  comment  is  that  it's  fas- 
cinating to  think  that  a  general  of  the 
army  like  Alexander  the  Great  would 
be  the  one  to  perform  a  tracheotomy. 
Imagine  General  Norman  Schwarz- 
kopf or  General  George  Patton  having 
to  perform  that  operation  to  save  a 
soldier's  life!  The  question  is  in  re- 
gard to  Jackson's  description  in  1909 
of  the  tracheotomy  operation.  I  believe 
he's  given  credit  for  modern  trache- 
otomy, based  on  his  1909  report  in 


Laiyngoscope.  Was  that  credit  due? 
Did  he  really  propose  a  novel  tech- 
nique of  maintaining  an  airway,  or  was 
his  work  just  a  continuation  of  ad- 
vances that  he  and  others  had  made  in 
that  field? 

Stoller:  That's  a  wonderful  question. 
I  didn't  encounter  that  paper  in  my 
research  for  this.  The  difficulty  I  have 
in  answering  is  that,  although  trache- 
otomy was  cited  by  many  others,  lit- 
erally thousands  of  years  before,  the 
attention  to  detail  in  its  description  was 
rather  sparse.  So,  though  in  fact  he 
may  be  credited  with  the  first  detailed 
description  of  the  technique,  it's  hard 
to  comment  as  to  whether  it  was  a 
leap  in  the  actual  technique,  because 
the  technique — as  far  as  I  can  tell — 
was  poorly  described  by  his  predeces- 
sors. So  it's  another  lesson,  it  seems 
to  me,  on  the  importance  of  carefully 
documenting  details,  of  which  he  was 
a  champion  in  describing  the  laryngo- 
scope and  the  technique  of  its  place- 
ment. Careful  description  of  the  tech- 
nique often  places  ownership  of  the 
technique  itself  in  medical  history, 
even  if  you  yourself  were  not  the  au- 
thor of  the  technique.  He  clearly  was 
not  the  first  person  to  ever  do  this.  It 
had  been  done  hundreds  or  thousands 
of  years  before,  but  I  think  his  de- 
scription is  the  most  careful  one,  at 
least  of  which  I  am  aware. 

Hurford:  Just  to  give  a  couple  of 
Boston  references.  You  mentioned  that 
people  have  descriptions  applied  to 
them  even  if  they  don't  do  it,  and  in 
Morton's  case  it  certainly  is  not  when 
you  do  it  or  how  you  do  it,  but  where 
you  do  it  and  how  you  promote  it.  In 
this  case,  general  anesthesia  by  ether 
inhalation  was  then  performed  in  En- 
gland only  2  months  after  Morton's 
demonstration. '  So  communications  in 
the  case  of  ether  were  much  more  rapid 
than  some  of  the  other  descriptions, 
indeed  because  it  was  presented  at  a 
prestigious  forum. 


REFERENCE 

I .  Spence  AA.  Ether  anesthesia  comes  to  Lon- 
don. December  1846.  Br  J  Anaesth  1996; 
77(6):705-706. 

Thompson:  One  of  the  many  things 
I  enjoyed  about  your  talk  was  the  ob- 
servation that  Hooke  was  one  of  the 
people  who  recognized  the  importance 
of  the  airway,  because  in  a  review  of 
the  development  of  extracorporeal 
membrane  oxygenation  I  found  that 
he  was  one  of  the  early  people  to  ob- 
serve that  blood  could  be  oxygenated 
outside  the  body.  It  makes  me  think 
that  all  through  history  there  have  been 
people  who  are  just  better  than  most 
of  us  at  making  observations  that  al- 
low others  to  make  quantum  leaps. 

Stoller:  I  think  that's  a  lovely  con- 
cept. One  of  the  other  take-home  points 
of  this  research  expedition  was  that 
many  of  the  names  that  appear  in  this 
list  of  accomplishments  are  also 
known  for  things  widely  disparate 
from  the  airway  developments.  For  ex- 
ample, consider  Trousseau,  whom  we 
think  of  in  relation  to  the  Trousseau 
syndrome  of  migratory  superficial 
thrombophlebitis  as  an  indication  of 
an  internal  malignancy;  or  Trendelen- 
burg, the  position  and  the  airway;  or 
Eisenmenger,  who  was  the  author  of 
the  first  cuirass  device  on  the  chest, 
but  who  is  better  known  for  Eisen- 
menger's  physiology  (as  you  get  right- 
to-left  shunt  through  a  patent  foramen 
ovale).  So,  obviously,  there  was  an 
intellectual  versatility  about  people 
300  years  ago,  which  I  found  refresh- 
ing, and  which  I  think  belies  our  cur- 
rent highly  specialized,  focused  inter- 
est, and  reminds  me  of  Pasteur's 
comment  that  "chance  favors  the  pre- 
pared mind."  There  were  a  bunch  of 
prepared  minds  looking  around  and 
making  similar  observations  across  a 
broad  array  of  medical  issues,  not  just 
focused  on  esoteric  things. 

Heffner:  Jamie,  I  particularly  en- 
joyed how  you  wove  into  your  talk 


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The  History  of  Intubation,  Tracheotomy,  and  Airway  Appliances 


the  social  transformation  of  medicine 
and  the  dissemination  of  icnowiedge 
among  medical  groups.  With  your  ex- 
perience in  working  and  making  big 
contributions  in  alpha  .-antitrypsin  de- 
ficiency registries,  do  you  think  we 
really  have  a  mechanism  now  to  rap- 
idly disseminate  findings  in  airway 
disease?  Considering  that  every  dis- 
ease is  cross-disciplinary  to  some  de- 
gree, there  may  be  nuggets  out  in  other 
fields  that  are  difficult  to  discover.  Is 
there  something  we  should  look  for- 
ward to  in  our  future  history  of  how 
we  can  more  rapidly  learn  from  other 
fields  and  disseminate  information? 

Stoller:  Wonderful  question.  In  this 
historical  perspective,  I  was  more 
struck  by  the  absence  of  mechanisms 
to  communicate  or  to  make  the  infor- 
mation available  at  all.  The  current 
lesson  to  which  you're  alluding,  of 
which  certainly  many  of  us  are  guilty, 
is  that  we  all  labor  in  our  own  vine- 
yards, and  we  don't  have  the  more 
ecumenical  perspective,  if  you  will,  to 
read  literatures  outside  the  literature 
in  which  we're  comfortable.  I'm  not 
sure  we  have  a  mechanism  to  encour- 
age people  to  look  far  afield.  I  think 
we  are  substantially  better  off  by  vir- 
tue of  having  journals  and  conferences 
that  in  a  relatively  rapid  time  frame 
can  at  least  make  the  information  avail- 
able. It  gets  to  the  ".  .  .  bring  the  horse 
to  water,  but  you  can't  make  him 
drink"  phenomenon.  The  information 
is  out  there,  but  now  it's  not  the  lack 
of  access  to  the  information,  but  our 
own  personal  inadequacies  that  lead 
us  to  be  rather  narrow-minded  and  tun- 
nel-visioned  in  the  literature.  But  I  wel- 
come your  thoughts  as  to  how  to  fix 
that.  It's  a  problem  of  medical  educa- 
tion, discipline,  and  cross-fertilization, 
which  I'm  sure  we  still  have  a  lot  to 
learn  about. 


change  in  medicine  as  well.  Aren't  you 
more  of  a  "business"  man? 

Pierson:*  I  just  wanted  to  briefly 
raise  a  question  that  I  hope  we  will 
revisit  tomorrow  morning  when  John 
(Heffner)  gives  his  talk  on  tracheot- 
omy, and  that  is:  Will  it  be  possible 
for  this  group  to  reach  consensus  as  to 
the  use  of  the  terms  tracheotomy  and 
tracheostomy?  This  is  something  I've 
been  intrigued  by  for  some  years,  be- 
cause my  observation  has  been  that 
there  is  no  consensus.  Perhaps  by 
reaching  consensus  in  this  group,  we 
can  make  one  small  step. 

Stoller:  For  what  it' s  worth,  although 
I  didn't  explicitly  make  the  point,  my 
talk  was  crafted  based  on  the  distinc- 
tion between  the  two,  which  is  one  of 
the  tracheotomy  being  a  crude — and 
I'll  stand  corrected  perhaps  tomor- 
row— but  a  crude  incision  into  the  air- 
way without  the  expectation  of  perma- 
nence, and  tracheostomy  referring  to 
creating  an  incision  with  the  intent  of 
creating  a  hole  that  is  surgically  crafted 
and  the  intent  of  maintaining  patency 
outside  of  the  acute  intervention  of  stick- 
ing a  device  into  the  airway,  but  I'd  be 
delighted  to  be  corrected. 

Reibel:    You  are  correct. 

Pierson:  You  also  used  the  term  "tra- 
cheotomy tube"  in  your  talk. 

Stoller:    A  typo! 

Bishop:  You  mentioned  the  Murphy 
eye  as  an  advance.  I  had  always  as- 
sumed that  the  Murphy  eye  was  a  rea- 
sonable thing  to  have  and  fairly  stan- 
dard, until  some  years  ago.  when  I 
was  putting  together  a  book.  I  had  a 
representative  of  Sheridan  Catheter 
write  about  the  manufacturing  process 


in  the  tracheal  tubes,  and  he  com- 
mented how  annoyed  manufacturers 
were  at  having  to  put  in  the  Murphy 
eye.  He  noted  that  there  was  no  evi- 
dence that  it  was  a  benefit  and  that  it 
was  an  annoyance  to  them  because 
the  little  holes  they  have  to  punch  out 
sometimes  don't  get  punched  per- 
fectly. They  then  have  to  worry  about 
somebody  aspirating  a  little  piece  of 
plastic. 

Stoller:  The  issue  of  evidence  is  an 
important  one.  His  description  was  a 
case  report  of  about  3  instances  in 
which  he  thought  it  was  a  good  idea. 
He  used  an  example  of  a  technique 
that  has  found  its  way  into  modern 
practice  on  the  basis  of  his  proposal 
that  it  was  a  reasonable  way  to  pro- 
vide extra  access  to  bronchial  secre- 
tions, so  that  one  lumen  couldn't  get 
occluded  and  one  could  conceivably 
have  access  to  more  than  one.  This 
technique  found  its  way  into  modern 
practice  simply  based  on  his  propos- 
ing it  in  1941  in  a  single  paper  from 
Harper  Hospital. 

Durbin:  In  my  presentation  on  Spe- 
cial Purpose  Endotracheal  Tubes,  I 
also  address  the  other  ways  things  get 
into  practice,  one  being  consensus  or 
standards  development.  In  fact,  Magill 
and  Murphy  tubes  (with  and  without 
the  eye)  are  available  from  most  man- 
ufacturers. So  you  don't  have  to  use 
tubes  with  the  Murphy  eye.  There  are 
a  series  of  reports  on  complications  in 
the  literature,  one  of  which  is  in  Re- 
.spiRATORY  Care,  of  a  suction  catheter 
being  entangled  into  the  Murphy  eye.' 
So  the  eye  is  not  a  "be  all  and  end 
all,"  and  as  far  as  I  know,  there  is  no 
documentation  that  either  shape  pre- 
vents the  complications  it  was  intended 
to  or  that  it  is  superior  to  any  other 
solution  of  that  particular  problem. 


Durbin:  I  would  also  point  out  that 
many  of  the  people  you  mentioned 
weren't  even  physicians.  They  were 
businessmen,  astronomers,  and  sailors. 
Perhaps  we're  going  to  make  that 


*  David  J  Pierson  MD.  Division  of  Pulmonary 
&  Critical  Care  Medicine.  Department  of  Med- 
icine. University  of  Washington.  Seattle.  Wash- 
ington. 


REFERENCE 

1.  Milisch  RA.  Rhn  DS.  Schell  SA.  Re- 
moval of  a  closed-system,  directional  tip 
suction  catheter.  Respir  Care  199-'i:40(4): 
438-441. 


Respiratory  Care  •  June  1999  Vol  44  No  6 


603 


Indications  for  Translaryngeal  Intubation 


Dean  R  Hess  PhD  RRT  FAARC 


Introduction 

Indications  for  Translaryngeal  Intubation 
Maintenance  of  Airway  Patency 
Protection  of  the  Airway  from  Aspiration 
Positive  Pressure  Ventilation 
Facilitation  of  Pulmonary  Toilet 
Use  of  High  Oxygen  Concentrations 
Contraindications  to  Endotracheal  Intubation 

[Respir  Care  1999;44(6):604-609]  Key  words:  translaryngeal  intubation,  en- 
dotracheal tube  resistance,  upper  airway  obstruction,  airway  protection. 


Introduction 

Invasive  airway  management  is  an  essential  component 
of  critica]  care  practice.  The  technical  aspects  of  acute 
airway  management  and  management  of  the  difficult  air- 
way are  addressed  in  detail  in  the  peer-reviewed  literature. 
However,  there  is  a  relative  dearth  of  literature  regarding 
the  indications  for  intubation.  Many  textbooks  of  respira- 
tory care,  anesthesia,  and  critical  care  present  only  a  cur- 
sory overview  of  the  indications  for  intubation,  usually 
preceding  an  in-depth  discussion  of  the  technical  aspects 
of  airway  management.  In  the  1990s  some  of  the  tradi- 
tional indications  for  endotracheal  intubation  have  been 
challenged  and,  increasingly,  noninvasive  efforts  are  being 
employed  to  avoid  intubation.  This  paper  reviews  the  tra- 
ditional indications  for  endotracheal  intubation  and  dis- 
cusses some  of  the  issues  related  to  those  indications. 

Indications  for  Translaryngeal  Intubation 

Indications  for  airway  management  are  addressed  in  the 
Clinical  Practice  Guidelines  of  the  American  Association 
for  Respiratory  Care. '  General  conditions  requiring  airway 
management  are:  impending  or  actual  airway  compromise, 
respiratory  failure,  and  the  need  to  protect  the  airway. 


Dean  R  Hess  PhD  RRT  FAARC  is  affiliated  with  Respiratory  Care 
Services,  Massachusetts  General  Hospital,  Harvard  Medical  School,  Bos- 
ton, Massachusetts. 

Correspondence:  Dean  Hess  PhD  RRT  FAARC,  Respiratory  Care,  Elli- 
son 401,  Massachusetts  General  Hospital,  55  Fruit  Street,  Boston  MA 
02114.  Email:  dhess@partners.org. 


Specific  conditions  requiring  management  of  the  airway 
are  listed  in  Table  1 .  Conditions  requiring  emergency  tra- 
cheal intubation  are  listed  in  Table  2. 

Commonly  listed  indications  for  endotracheal  intuba- 
tion are:  (1)  maintenance  of  airway  patency,  (2)  protection 
of  the  airway  from  aspiration,  (3)  application  of  positive 
pressure  to  the  airway,  (4)  facilitation  of  secretion  clear- 
ance, and  (5)  delivery  of  high  oxygen  concentrations. ^^ 
Although  endotracheal  intubation  is  lifesaving  for  many 
patients,  many  of  these  traditional  indications  are  not  ab- 
solute. 

Maintenance  of  Airway  Patency 

Alternatives  to  endotracheal  intubation''  that  can  be 
used  to  provide  upper  airway  patency  include  oral  and 
nasal  airways, ■'*■''  Combitubes,  (Kendall  Healthcare, 
Mansfield,    Massachusetts)''-*   and   laryngeal   mask   air- 


ways.' 


Advantages  and  disadvantages  of  these  ap- 


proaches are  listed  in  Table  3.  Generally,  these  devices  are 
used  for  short-term  airway  management  and  must  be  con- 
verted to  an  endotracheal  tube  for  long-term  management 
of  the  airway. 

In  recent  years  there  has  been  increasing  enthusiasm  for 
the  laryngeal  mask  airway.  There  are  several  issues  with 
the  use  of  the  laryngeal  mask  airway  for  emergency  air- 
way management.  First,  it  does  not  absolutely  protect 
against  regurgitation  and  aspiration  of  stomach  con- 
tents.^o-^'  Second,  it  is  difficult  to  provide  high  airway 
pressures,  which  are  occasionally  required  for  emergency 
ventilation.'*  Nonetheless,  the  laryngeal  mask  airway  has 
been  used  successfully  as  a  first  airway  during  cardiopul- 


604 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Indications  for  Translaryngeal  Intubation 


Table  I.      Specific  Conditions  Requiring  Airway  Management 
(Adapted  from  Reference  1.) 

•  Obstruction  of  artificial  airway 

•  Apnea 

•  Acute  traumatic  coma 

•  Penetrating  neck  trauma 

•  Cardiopulmonary  arrest  and  unstable  dysrhythmias 

•  Severe  bronchospasm 

•  Severe  allergic  reactions  with  cardiopulmonary  compromise 

•  Pulmonary  edema 

•  Sedative  or  narcotic  drug  effect 

•  Foreign  body  airway  obstruction 

•  Choanal  atresia  in  neonates 

•  Aspiration  or  risk  of  aspiration 

•  Severe  laryngospasm 

•  Self-extubation 


Table  2.      Conditions  Requiring  Emergency  Tracheal  Intubation 
(Adapted  from  Reference  1.) 

•  Persistent  apnea 

•  Traumatic  upper  airway  obstruction 

•  Accidental  extubation  of  a  patient  unable  to  maintain  adequate 

spontaneous  ventilation 

•  Obstructive  angioedema 

•  Massive  uncontrolled  upper  airway  bleeding 

•  Coma  with  potential  for  increased  intracranial  pressure 

•  Infection-related  upper  airway  obstruction  (eg,  epiglottitis,  acute 

uvular  edema,  tonsillopharyngitis  or  retropharyngeal  abscess, 
supportive  parotitis) 

•  Laryngeal  and  upper  airway  edema 

•  Absence  of  airway  protective  reflexes 

•  Cardiopulmonary  arrest 

•  Massive  hemoptysis 

•  Neonatal  or  pediatric  disorders  (eg,  perinatal  asphyxia,  severe 

tonsillar  hypertrophy,  severe  laryngomalacia.  bacterial  tracheitis, 
neonatal  epignathus.  obstruction  from  abnormal  laryngeal  closure 
due  to  arytenoid  masses,  mediastinal  tumors,  congenital 
diaphragmatic  hernia,  presence  of  thick  and/or  particulate 
meconium  in  amniotic  fluid) 


monary  resuscitation,  and  has  been  shown  to  provide  more 
effective  ventilation  than  bag-vaive-mask  ventilation.'''"'^ 
A  properly  positioned  endotracheal  tube  effectively  by- 
passes upper  airway  obstruction.  However,  the  resistance 
to  air  flow  through  an  endotracheal  tube  is  greater  than 
that  of  a  normal  native  upper  airway. 22-34  Lofaso  et  aF** 
proposed  use  of  the  Blasius  resistance  formula  to  estimate 
the  effective  diameter  of  endotracheal  tubes: 


AP   =   K  X 


{LID'-'")  X  pi"  25  X  pn.75  X  V' 


ameter  of  the  tube,  /x  is  gas  viscosity,  p  is  gas  density,  and 
V  is  flow  through  the  tube.  Guttman  et  aF^  reported  a 
nonlinear  approximation  of  the  pressure  drop  across  the 
endotracheal  tube  (APg-pT): 


APf 


Kl  X  V** 


where  AP  is  the  pressure  drop  along  the  length  (L)  of  the 
endotracheal  tube,  K  depends  upon  the  shape  of  the  tube 
cross  section  (K  =  0.24  for  circular  tubes),  D  is  the  di- 


where  Kl  and  K2  are  coefficients  that  were  determined 
in  the  laboratory  and  validated  in  intubated  patients.  For 
example,  for  an  uncut  8  mm  endotracheal  tube,  Kl  is  6.57 
and  K2  is  1 .94.  It  should  also  be  recognized  that  endotra- 
cheal tube  resistance  increases  in  situ,^'*-^^-'''  most  likely 
because  of  progressive  reduction  of  the  tube  diameter  sec- 
ondary to  mucus  deposition.  Nasal  intubation  does  not 
produce  greater  resistance  than  oral  intubation  for  compa- 
rable endotracheal  tube  sizes. 22 

Whether  endotracheal  tube  resistance  poses  a  clinical 
concern  for  increased  work  of  breathing  in  adults  is  con- 
troversial. The  imposed  work  of  breathing  through  the 
endotracheal  tube  is  modest  at  usual  minute  ventilations 
for  the  tube  sizes  most  commonly  used  for  adults  (Fig.  1). 
Brochard  et  al''''  reported  a  27%  increase  in  work  of  breath- 
ing due  to  the  endotracheal  tube,  and  found  that  pressure 
support  ventilation  of  3.4-14.4  cm  HjO  was  sufficient  to 
compensate  for  this  additional  work.  Fiastro  et  aF"  re- 
ported that  a  pressure  support  level  of  2-20  cm  HjO  elim- 
inated the  imposed  work  from  the  ventilator  and  endotra- 
cheal tube.  In  both  of  these  studies  there  was  wide  variability 
among  patients  in  the  appropriate  level  of  pressure  support 
needed  to  overcome  the  imposed  work.  Automatic  tube 
compensation"-'"  was  recently  introduced  with  the  Drager 
Evita  ventilator  (Drager  Inc,  Telford,  Pennsylvania).  For  a 
designated  endotracheal  tube  size,  this  feature  monitors 
flow  and  varies  both  the  inspiratory  and  expiratory  pres- 
sure at  the  proximal  airway  to  maintain  tracheal  pressure 
at  the  target  level,  which  effectively  compensates  for  en- 
dotracheal tube  resistance.  Experience  to  date  with  auto- 
matic tube  compensation  is  limited. 

Several  recent  studies  cast  doubt  on  the  importance  of 
endotracheal  tube  resistance  during  short  trials  of  sponta- 
neous breathing.  Esteban  et  al"*"  reported  similar  outcomes 
when  spontaneous  breathing  trials  were  conducted  with 
pressure  support  (7  cm  HjO)  or  with  a  T-piece.  Straus  et 
aH'  reported  that  the  work-of-breathing  through  the  endo- 
tracheal tube  amounted  to  only  about  10%  of  the  total 
work  of  breathing.  That  study  further  reported  that  the 
work  of  breathing  during  a  2-hour  spontaneous  breathing 
trial  with  a  T-piece  was  similar  to  the  work  of  breathing 
immediately  following  extubation.  Although  prolonged 
spontaneous  breathing  through  an  endotracheal  tube  is  not 
desirable  (because  of  the  resistance  of  the  tube),  this  may 
not  be  important  for  short  periods  of  spontaneous  breath- 
ing to  assess  extubation  readiness. 


Respiratory  Care  •  June  1999  Vol  44  No  6 


605 


Indications  for  Translaryngeal  Intubation 


Table  3.      Advantages  and  Disadvantages  of  Alternatives  to  Endotracheal  Intubation  for  Maintaining  Upper  Airway  Patency 


Advantages 


Disadvantages 


Oral  and  nasal  airways 


Combitube 


Laryngeal  mask  airway 


Little  training  required 

No  special  equipment  necessary 

Inexpensive 

Can  be  quickly  placed 


Less  skill  than  bag-valve-mask  or  intubation 
No  special  equipment  necessary 
Protection  against  aspiration 
Facilitates  positive  pressure  ventilation 


Easy  to  insert 

No  special  equipment  necessary 

Can  intubate  without  removing  laryngeal  mask  airway 

Avoids  laryngeal  and  tracheal  trauma 

Maintains  patent  upper  airway 


Does  not  guarantee  airway  patency 

May  worsen  obstruction 

Poorly  tolerated  by  awake  patient  '_ 

Does  not  prevent  aspiration 

Short-term  use 

Does  not  facilitate  positive  pressure  ventilation 

Difficulty  distinguishing  tracheal  vs  esophageal  placement 

Short-term  use 

Aspiration  during  removal 

Cannot  suction  in  esophageal  position 

Only  one  size  (adult)  ^ 

Potential  for  esophageal  injury 

Short-term  use 

Aspiration  not  absolutely  avoided 

Cannot  provide  high  ventilation  pressures  if  needed 


150 

r 

» 

140 
130 
120 
lU) 
100 

A— « 

6  Tube                   / 

7  Tube                  / 

8  Tube                   /  5. 

9  Tube                /  / 
0  Tube                 /  / 

90 

- 

/  / 

Work         80 
Joules/min   70 

. 

/// 

fiO 

- 

//  / 

50 

■ 

//  /  / 

40 

- 

/I  // 

30 

- 

//// 

20 

- 

Aryy 

10 

—J 

^^^:i^^\___»_— -• 

°. 

)       5 

f  W"^     t"""      1             1             1 

10     15     20      25     30 

V£  L/mIn 

Fig.  1.  Relationship  between  work  of  breathing  (WOB)  and  minute 
ventilation  with  different  sized  endotracheal  tubes.  Note  that  the 
differences  between  endotracheal  tube  sizes  become  greater  with 
minute  ventilations  greater  than  10  L/min.  (From  Reference  31, 
with  permission.) 


Protection  of  the  Airway  from  Aspiration 

The  cuff  of  the  endotracheal  tube  is  expected  to  protect 
the  lower  respiratory  tract  from  aspiration  of  gastric  con- 
tents. However,  it  has  been  known  for  many  years  that 
silent  aspiration  occurs  past  the  cuff  of  the  endotracheal 
tube.-*-  Aspiration  of  pharyngeal  secretions  is  a  common 
cause  of  ventilator-associated  pneumonia. •♦''  Aspiration  is 
more  common  with  the  high-volume  low-pressure  cuffs 
used  with  current  generation  endotracheal  tubes  to  prevent 


suction 
port 

Fig.  2.  Mallinckrodt  Hi-Lo  Eval  Endotracheal  tube.  This  tube  has  an 
evacuation  (suction)  port  above  the  cuff  on  the  dorsal  side  of  the 
tube  to  facilitate  suctioning  of  subglottic  secretions. 


tracheal  wall  trauma.-'-*-'*'^  These  cuffs  develop  longitudi- 
nal folds  when  inflated  in  the  trachea,  and  liquid  pharyn- 
geal secretions  are  silently  aspirated  through  these  invagi- 
nations of  the  cuff.  Increasing  the  cuff  pressure  (eg,  to 
20-25  mm  Hg)  decreases,-*^'*'*-'*"  but  does  not  completely 
eliminate,  this  aspiration.'*'* 

Several  studies  have  evaluated  the  role  of  aspiration  of 
subglottic  secretions  in  preventing  ventilator-associated 
pneumonia,  and  an  endotracheal  tube  to  achieve  this  is 
now  commercially  available  (Fig.  2).  Mahul  et  al  reported 
a  twice  lower  incidence  of  nosocomial  pneumonia  with 
hourly  aspiration  of  subglottic  secretions.^'  Valles  et  al 
reported  that  continuous  aspiration  of  subglottic  secretions 
was  associated  with  a  reduction  (by  about  one  half)  in 
ventilator-associated  pneumonia."  Relic  et  al  reported  a 


606 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Indications  for  Translaryngeal  Intubation 


Table  4.      Exclusion  Criteria  for  NPPV  (From  Reference  57, 
with  permission.) 

Absolute 

•  Respiratory  arrest 

•  Cardiorespiratory  instability 

•  Uncooperative  patient 

•  Recent  facial,  esophageal,  or  gastric  surgery 

•  Craniofacial  trauma  or  burns 

•  High  aspiration  risk  (unable  to  manage  secretions) 

•  Inability  to  protect  airway 

•  Fixed  anatomic  abnormalities  of  the  nasopharynx 
Relative 

•  Extreme  anxiety 

•  Massive  obesity 

•  Copious  secretions 

•  Acute  respiratory  distress  syndrome  as  etiology  of  acute  respiratory 
failure 


5-times  greater  likelihood  of  ventilator-associated  pneu- 
monia when  continuous  aspiration  of  subglottic  secretions 
was  not  used.''" 

Several  studies  have  also  reported  that  biofilm  forma- 
tion in  endotracheal  tubes  can  serve  as  a  source  of  bacte- 
rial colonization  of  the  lungs.'^^'^'*  It  has  been  hypothesized 
that  these  bacterial  aggregates  can  be  dislodged  from  the 
interior  lumen  of  the  endotracheal  tube  during  standard 
usual  airway  care  procedures  such  as  suctioning. 

Positive  Pressure  Ventilation 

Traditionally,  an  endotracheal  tube  was  placed  to  pro- 
vide positive  pressure  to  the  airway.  Of  concern  is  the 
potential  for  gastric  insufflation  if  positive  pressure  is  ap- 
plied by  face  mask.  However,  the  esophageal  opening  pres- 
sure is  about  20  cm  HjO,  and  gastric  insufflation  is  min- 
imized by  keeping  pharyngeal  pressures  less  than  this 
level. ■■'•^■''^  Continuous  positive  airway  pressure  and  nonin- 
vasive positive  pressure  ventilation  (NPPV)  have  been  in- 
creasingly used  in  order  to  avoid  endotracheal  intubation 
in  certain  patients.-"*"  A  recent  meta-analysis  also  sug- 
gests that  survival  may  be  improved  with  the  use  of  NPPV 
in  selected  patients. ^'^  Despite  the  increasing  use  of  NPPV, 
there  are  many  patients  in  whom  this  approach  is  not  ap- 
propriate (Table  4).  Although  NPPV  improves  outcomes 
in  properly  selected  patients,  it  is  appropriate  in  only  a 
small  subset  of  patients  requiring  ventilatory  support.  Even 
when  used  by  skilled  clinicians  with  appropriately  selected 
patients,  NPPV  will  fail  in  about  25%  of  cases  and  endo- 
tracheal intubation  will  be  necessary.'''  Complications  can 
occur  with  NPPV,  although  these  are  usually  minor.''- 

Facilitation  of  Pulmonary  Toilet 

Endotracheal  intubation  has  been  performed  to  provide 
a  suction  route  to  facilitate  clearance  of  tracheal  secre- 


tions. In  many  patients,  however,  secretion  clearance  can 
be  facilitated  without  the  need  of  an  endotracheal  tube. 
Techniques  that  are  commonly  used  for  secretion  clear- 
ance include  chest  physiotherapy,''^  cough  instruction,''^ 
nasotracheal  suction,""*  bronchoscopy,''"  and  positive  expi- 
ratory pressure  or  flutter  valves.''^  In  patients  with  neuro- 
muscular disease,  the  In-Exsufflator  (JH  Emerson,  Cam- 
bridge, Massachusetts)  has  been  used  effectively  to  remove 
secretions  without  the  need  for  an  artificial  airway."**  High- 
frequency  chest  wall  compression  devices  have  also  been 
used  to  facilitate  secretion  clearance."''  Although  transla- 
ryngeal intubation  facilitates  tracheal  suction,  there  are 
few  patients  who  require  an  artificial  airway  solely  for  this 
indication. 

Use  of  Higli  Oxygen  Concentrations 

Devices  such  as  a  nonrebreathing  mask  typically  do  not 
deliver  100%  oxygen  because  they  fit  poorly  to  the  face 
and  because  the  oxygen  flows  delivered  are  considerably 
less  than  the  patient's  peak  inspiratory  flow.^"  Translaryn- 
geal intubation  allows  a  tight-fitting  oxygen  administra- 
tion device.  However,  this  will  not  deliver  a  high  or  pre- 
cise oxygen  concentration  if  the  flow  is  inadequate.  Precise 
and  high  oxygen  concentrations  can  be  administered  with 
a  face  mask  and  without  translaryngeal  intubation  if  the 
flow  from  the  device  is  sufficient.^'  A  limitation  of  this 
approach  is  that  the  patient  receives  no  supplemental  ox- 
ygen if  the  face  mask  is  removed. 

Contraindications  to  Endotraclieal  Intubation 

There  are  several  contraindications  to  endotracheal  in- 
tubation. If  the  upper  airway  is  completely  obstructed  or  if 
there  is  massive  trauma  to  the  upper  airway,  a  surgical 
airway  (eg,  tracheotomy)  is  likely  necessary.  Because  of 
the  hazards  associated  with  intubation,  this  procedure  is 
relatively  contraindicated  in  the  absence  of  a  clinician 
skilled  to  perform  this  procedure.  Finally,  endotracheal 
intubation  is  contraindicated  if  the  patient  wishes  not  to  be 
intubated. 

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Discussion 

Durbin:  Although  in  atdults  the  re- 
duction in  airway  (Jiameters  impo.sed 
by  the  endotracheal  tube  i.s  usually  in- 
consequential, it  may  in  fact  be  a  real 
issue  in  children. 

Hess:  Obviously,  my  talk  was  with 
regard  to  adults,  because  that's  who  I 
take  care  of,  but  I  would  be  interested 
in  any  comments  that  you  (Ann 
Thompson)  have  regarding  any  of 
these  issues  related  to  children, 

Stauffer:  Do  we  know  how  widely 
the  irrigating  endotracheal  tube  is  used 
currently?  It  would  seem  to  have  some 
merit  based  on  the  evidence  available. 
Who  uses  it,  and  if  we're  not  using  it, 
why? 

Hess:  The  tube  you're  talking  about 
is  the  one  with  continuous  aspiration 
of  subglottic  secretions?  I  don't  know 


how  widely  that  is  used.  I  think  one  of 
the  issues  with  it  now  is  that  it  adds 
significantly  to  the  cost  of  intubation. 
The  problem  I  have  with  its  use  is  that 
if  you  change  out  a  traditional  endo- 
tracheal tube  for  this  tube,  the  reintu- 
bation  process  increases  the  risk  of 
ventilator-associated  pneumonia.  So 
unless  you  use  this  new  tube  for  every 
intubation,  you  won't  get  the  benefit. 

Ritz:  Sotneone  told  me  that  a  dou- 
ble-lumen tube  with  suctioning  port 
costs  $15  or  $18.  Does  that  sound 
right? 

Hess:  That  does  sound  correct.  So 
that  more  than  triples  the  cost. 

Ritz:  And  the  other  thing  is,  does  it 
change  the  internal/external  diame- 
ters— an  8  for  an  8,  a  7  for  a  7?  Do  you 
get  a  bigger  tube  out  of  it?  Do  you  know? 

Hess:     1  think  they're  sized  the  same. 


Stoller:  In  the  context  of  historical 
inquiry,  you've  addressed  the  issue  of 
airway  caliber,  but  perhaps  in  antici- 
pating Charlie  Durbin' s  talk  about  spe- 
cialty tubes,  I'll  invoke  a  little  piece 
of  history  I  didn't  address  that  gets  to 
the  history  of  double-lumen  tubes,  and 
I'll  quote  here  from  Frank  Robert- 
shaw's  paper  from  1962  in  which  he 
adapted  Bjork  and  Carlen's  original 
double-lumen  endotracheal  tube  from 
several  years  before.  He  cites  the  ad- 
vantages of  this  tube  regarding  lumen 
caliber,  and  wrote: 

Despite  its  many  advantages, 
Carlen's  catheter  has  not  found  uni 
versal  acceptance  among  thoracic 
surgeons  and  anesthetists.  The  dif- 
ficulties of  placing  it  correctly  can 
soon  be  overcome.  A  more  serious 
objection  is  the  smallness  of  each 
lumen.  The  consequent  resistance 
to  gas  flows  is  largely  overcome  by 
the  use  of  controlled  respiration,  but 
Jenkins  and  Clark  have  suggested 


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609 


Indications  for  Translaryngeal  Intubation 


the  increased  resistance  to  expira- 
tion may  represent  a  contraindica- 
tion to  its  use  in  cases  with  gross 
emphysema.  The  passage  of  suction 
catheters  of  sufficient  size  to  deal 
with  fixed  secretions  is  also  diffi- 
cult.' 


So,  historically  at  least,  the  concept  of 
lumen  caliber  is  not  only  one  of  work 
of  breathing  on  inspiring  air,  but  of 
the  positive  end-expiratory  pressure 
(PEEP),  or  auto-PEEP  phenomenon, 
which  was  anticipated  in  this  double- 
lumen  discussion,  as  well  as  that  of 
managing  airway  secretions  through  a 
very  small  lumen  in  Carlen's  original 
double-lumen  tube  with  a  carinal  hook. 


REFERENCE 

I.  Robertshaw  FL.  Low  resistance  double- 
lumen  endobronchial  tubes.  Br  J  Anaesth 
1962;34:576-579. 

Hess:  And  that  was  a  very  small 
lumen  tube. 

Stoller:  Oh,  yes.  It  was  extremely 
small.  At  some  level  of  luminal  cali- 
ber, it  probably  matters  a  little  bit. 

Hurford:  In  regard  to  Jamie 
Stoller' s  comment,  the  current  tubes 
that  we  have  for  Robertshaw  designs 
are  about  3.5-4  mm,  depending  on 
size  for  each  lumen.  The  Carlen'  s  cath- 
eter, while  not  much  smaller  as  far  as 
the  millimeter  diameter,  was  oddly 
shaped  as  well.  It  was  D-shaped  rather 
than  circular,  which  made  it  even  more 
difficult  to  pass  a  suction  catheter  in 
the  adult,  to  try  to  get  one  down  that's 
much  smaller  than  a  10  French  size 
just  becomes  silly  in  trying  to  get  rid 
of  secretions.  That  was  the  problem 
with  that  tube.  So,  yes,  as  with  God- 
zilla, size  does  matter  to  a  certain 
degree. 

If  I  could  get  back  to  the  issue  of 
clearance  of  secretions,  it  is  not  evi- 
dence-based medicine  but  an  experi- 
entially-based  medicine  that  I'd  like 
to  share.  Many  of  you  know  a  radiol- 


ogist named  Reggie  Greene  at  the  Mas- 
sachusetts General  Hospital.  When  I 
was  a  resident  I  would  come  to  radi- 
ology rounds  and  he  could  look  at  an 
x-ray  and  say  "Well,  this  patient's  go- 
ing to  be  developing  an  aspiration 
pneumonia  in  the  right  upper  lobe  in  3 
days."  And  3  days  later  he  did.  I  fi- 
nally got  up  enough  courage  to  ask 
him  "How  do  you  know  this?"  And 
he  said,  "Well,  look  right  above  the 
endotracheal  tube  cuff;  you  can  see 
that  the  superior  portion  of  the  cuff  is 
outlined  by  the  secretions  that  are 
pooled  above  the  cuff,  and  those  se- 
cretions will  come  down  through  the 
airway.  So,  if  the  x-ray  shows  those 
secretions  up  there,  you  can  then  do 
something  about  it."'  And  so  I  think 
there's  also  probably  something  to 
the  clearance  of  secretions,  and  you 
can  use  the  x-ray  to  try  to  screen  those 
people  from  whom  you  need  to  re- 
move secretions. 


REFERENCE 

1 .  Greene  R,  Thompson  S,  Jantsch  HS.  Tep- 
lick  R,  Cullen  DJ.  Greene  EM,  et  al.  De- 
tection of  pooled  secretions  above  endo- 
tracheal tube  cuffs:  value  of  plain 
radiographs  in  sheep  cadavers  and  patients. 
AJR  Am  J  Roentgenol  1 994;  1 63(6):  1 333- 
1337. 

Heffner:  That's  an  interesting  ob- 
servation that  I  wasn't  aware  of  be- 
fore, and  something  I'll  start  looking 
for  in  x-rays.  It  makes  me  think,  too, 
of  another  observation  in  the  inten- 
sive care  unit,  gleaned  from  broncho- 
scopic  bronchoalveolar  lavage  studies 
of  ventilator-associated  pneumonia. 
One  of  the  predictors  for  pneumonia 
is  airway  colonization,  which  occurs 
in  almost  anybody  who's  intubated. 
But  as  soon  as  the  bronchioles  dem- 
onstrate the  presence  of  colonization, 
pneumonia  occurs  a  few  days  later. 
So  the  strong  area  for  bacteria  is  above 
the  cuff,  and  then  as  the  pathogens 
make  their  way  down  the  airway,  pneu- 
monia eventually  develops.  Let  me  ask 
you  a  question  about  size.  You're  sug- 


gesting that  Brochard  and  other  peo- 
ple's work  looking  at  no  difference 
between  T-piece  trials  and  pressure- 
support  trials  might  indicate  that  for 
the  ventilated  patient,  the  caliber  of 
the  tube  and  airway  resistance  may 
not  make  an  impact  on  outcome.  Do 
you  think,  though,  that  these  studies 
enrolled  a  highly  screened  population, 
who  all  passed  weaning  parameters  in 
anticipation  of  weaning  from  the  ven- 
tilator and  that  their  findings  may  not 
generalize  to  other  patients  at  the  on- 
set of  intermittent  mandatory  ventila- 
tion? 

Hess:  I  think  it  may  not  apply  to  the 
patient  with  marginal  reserve,  the  pa- 
tient to  whom  I  think  you  are  refer- 
ring, or  to  patients  who  have  smaller 
tubes.  1  think  that  all  of  the  patients  in 
the  Straus  paper',  which  was  Bro- 
chard's  group,  had  endotracheal  tubes 
with  an  8  mm  internal  diameter,  for 
example.  1  think  that  in  a  patient  with 
marginal  reserve,  who  has  a  very  small 
endotracheal  tube,  it  certainly  can  have 
an  impact,  and  that  prolonged  sponta- 
neous breathing  through  an  airway  is 
probably  not  a  good  thing.  I  also  think 
that  some  of  the  things  we've  tradi- 
tionally been  concerned  about  with  re- 
sistance through  the  endotracheal  tube 
and  needing  a  little  bit  of  pressure  sup- 
port to  overcome  that  may  not  be  nec- 
essary, based  on  the  Esteban  study 
and  the  Straus  study.' 


REFERENCES 

1.  Straus  C,  Louis  B.  Isabey  D,  Lemaire  F. 
Harf  A,  Brochard  L.  Contribution  of  the 
endotracheal  lube  and  the  upper  airway  to 
breathing  workload.  Am  J  Respir  Crit  Care 
Med  l998;l57{l):23-30. 

2.  Esteban  A,  Alia  I.  Gordo  F,  Fernandez  R, 
Solsona  JF.  Vallverdu  I.  et  al.  Extubation 
outcome  after  spontaneous  breathing  trials 
with  T-tube  or  pressure  support  ventila- 
tion. The  Spanish  Lung  Failure  Collabo- 
rative Group.  Am  J  Respir  Crit  Care  Med 
1997:156(2  Pt  l):459^65.  Puhlished  er- 
ratum appears  in  Am  J  Respir  Crit  Care 
Med  I997:I56(6):2028. 


610 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Indications  for  Transi.aryngeal  Intubation 


Pierson:*  That  leads  into  the  ques- 
tion I  wanted  to  ask.  which  relates  to 
the  indications  for  mechanical  venti- 
lation. Of  your  5  basic  categories  of 
indication  for  endotracheal  intubation, 
only  one  of  the  5  mandated  inspira- 
tory positive  pressure.  In  my  intensive 
care  unit,  virtually  100%  of  patients 
who  require  intubation  wind  up  at- 
tached to  a  ventilator,  which  in  my 
institution  incurs  a  daily  charge  of  well 
over  $200.  Any  comment  about  that, 
and  whether  we  should  be  doing  a  bet- 
ter job  of  teaching  the  indications  so 
that  not  every  intubated  patient  has  to 
go  on  a  ventilator? 

Hess:  If  the  only  reason  you  need 
an  airway  is  to  bypass  upper  airway 
obstruction,  then  it  would  make  sense 
that  if  you  put  in  the  airway,  you  may 
not  necessarily  need  positive  pressure 
ventilation.  Is  that  your  point? 

Pierson:  Yes.  And  yet,  in  the  prac- 
tice that  1  observe,  it  is  virtually  always 
a  knee-jerk  response  to  write  ventilator 
orders  as  soon  as  a  tube  goes  in. 

Hess:  That's  an  interesting  observa- 
tion. Fm  trying  to  think  of  the  last 
time  that  I  saw  a  patient  intubated  who 
did  not  end  up  on  a  ventilator,  and  it"s 
very  infrequently  that  that  occurs. 

Pierson:  Because  even  if  they're 
only  on  5  cm  HjO  of  pressure  sup- 
port, they're  still  incurring  the  same 
daily  charge. 

Hess:  Right.  And  part  of  that  might 
be  the  amount  of  pharmacologic  sup- 
port that  the  patient  needs  to  get  the 
endotracheal  tube  in.  which  then  re- 
quires at  least  some  short  term  of  ven- 
tilatory support.  But  that's  a  very  in- 
teresting observation.  I  can  think  of 
very  few  instances  where  I  saw  a  pa- 


*  David  J  Pierson  MD.  Division  of  Pulmonary 
Critical  Care  Medicine.  Department  of  Medi- 
cine. University  of  Washington.  Seattle.  Wash- 
ington. 


tient  intubated  who  did  not  go  onto  a 
ventilator. 

Durbin:  I'd  like  to  put  my  2  cents 
in  here  because  I  think  you  said  that 
you  don' t  think  a  person  should  breathe 
spontaneously  through  an  endotra- 
cheal tube  without  mechanical  venti- 
lation for  a  long  period  of  time.  What 
do  you  base  that  on?  I  don't  think  the 
fact  that  we  do  ventilate  most  people 
with  endotracheal  tubes  should  mean 
that  we  should  ventilate  patients  or 
have  to.  One  of  the  special  purpose 
tubes  I'll  discuss  is  one  in  which  you 
can  instill  local  anesthetic  down  the 
outside  of  the  tube.  If  patient  toler- 
ance of  the  endotracheal  tube  is  the 
reason  for  sedation  and  ventilation, 
you  can  avoid  using  this.  Do  you  con- 
sider continuous  positive  airway  pres- 
sure (CPAP)  as  positive  pressure  ven- 
tilation or  not?  1  don't  think  it  is.  and 
we  usually  don't  need  a  ventilator  to 
provide  CPAP  in  my  institution. 

Pierson:  1  guess  the  distinction  is 
whether  you  need  a  ventilator  to  de- 
liver it.  In  the  case  of  CPAP.  you  can 
do  it  without  a  ventilator  attached,  but 
we  often  don't.  Obviously,  if  all  the 
patient  needs  is  something  you  can  do 
without  a  ventilator,  you  should  do  it 
without  a  ventilator. 

Hess:  It's  an  interesting  observation, 
because  certainly  it's  not  unusual  for 
patients  to  be  tracheostomized  and  not 
end  up  on  a  ventilator.  But  certainly 
with  an  endotracheal  tube  that  is  often 
what  occurs.  Bill,  do  you  want  to  ad- 
dress that? 

Hurford:  Those  people  who  are 
healthy  enough  not  to  require  a  ven- 
tilator, in  that  they  have  absolutely  no 
lung  injury  or  lung  disease,  don't  stay 
in  the  intensive  care  unit.  If  they  just 
have  an  endotracheal  tube  in  place  for 
a  little  bit  of  airway  obstruction  post- 
surgically,  they  generally  are  in  the 
post-anesthesia  care  unit  for  less  than 
48  hours.  They're  up  and  out.  So  we 
don't  see  them  because  they  don't 


come  to  us  in  our  unit.  And  certainly 
if  they  don't  come  to  our  practice  very 
routinely,  with  the  exception  of  maybe 
the  peritonsillar  abscess  or  other  oral 
abscess  patients,  those  patients  do  stay 
in  the  unit  with  their  tubes  just  at- 
tached to  a  little  tlow-by  humidified 
oxygen.  But  they  are  very  rare. 

Thompson:  As  a  pediatric  intensiv- 
ist.  I'm  surprised  to  recognize  that  our 
practice  is  remarkably  similar.  Resis- 
tance through  endotracheal  tubes  is  a 
constant  concern  of  ours.  Your  graph 
of  resistance  through  endotracheal 
tubes  stops  at  the  diameter  where  we 
begin.  We  have  a  small  number  of 
patients  with  6.0-8.0  mm  tubes  each 
year,  but  the  rest  require  3.0-.'i..'>  mm 
tubes.  Concern  about  resistance  to  air- 
flow through  these  tubes,  particularly 
at  the  low  end,  is  quite  realistic.  Main- 
taining spontaneous  breathing  requires 
more  effort,  and  the  risk  of  occlusion 
with  secretions  is  higher.  Recent  data 
suggest  that  using  pressure  support  {5 
cm  H^O)  effectively  overcomes  this 
excess  work. 

Hess:  If  I  can  interrupt,  I  was  going 
ask  how  well  this  has  been  studied  in 
that  patient  population,  because  if  you 
look  at  the  physics,  certainly  the  in- 
ternal diameter  of  the  tube  is  much 
smaller  for  a  newborn  or  a  child,  but 
the  tube  is  also  shorter,  and  the  in- 
spiratory and  expiratory  flows  of  the 
patient  are  much  lower.  Does  it  really 
translate  to  that  much  of  a  difference 
in  work? 

Thompson:  The  tubes  aren't  neces- 
sarily that  much  shorter  than  in  adults. 
We  do  tend  to  trim  them  to  minimize 
the  contribution  of  tube  length  to  re- 
sistance, but  diameter  has  a  much 
greater  impact  on  resistance.  Nonethe- 
less, you  are  correct  that  there  are  only 
very  limited  data.  Over  the  past  sev- 
eral years,  particularly  in  patients  with 
minimal  lung  disease,  we  have 
changed  our  clinical  practice  from 
slow,  steady  weaning  in  steps  of  2 
breaths  per  minute,  lo  intermillent  T- 


Respiratory  Care  •  June  1999  Vol  44  No  6 


61 


Indications  for  Translaryngeal  Intubation 


piece  trials  of  10  minutes  or  so.  If  a 
patient  maintains  a  comfortable  respi- 
ratory pattern,  we  extubate  them.  It's 
a  change  in  practice  supported  by  lit- 
tle but  our  own  observations  that  ven- 
tilation days  have  decreased  without 
an  increased  reintubation  rate.  I'm  also 
interested  in  the  difference  in  the  in- 
cidence of  ventilator-associated  pneu- 
monia in  children  compared  to  adults. 
We  see  a  leak  around  the  endotracheal 
tube  at  20-30  cm  HjO  in  most  patients. 
Presumably  there's  always  some  pas- 
sage of  secretions  around  the  tube  into 
the  trachea,  and  yet  we  have  a  very  much 
lower  incidence  of  pneumonia. 

Hess:     Is  the  upper  airway  colonized? 

Thompson:  Absolutely,  and  with  a 
similar  spectrum  of  nasty  organisms 
as  is  found  in  adults.  So  there  are  other 
factors  involved.  We  often  speak  of 
the  healthier  tissues  of  children,  which 
may  be  correct,  but  what  are  the  spe- 
cific characteristics  that  make  infec- 
tion less  common?  Finally  with  re- 
spect to  intubation  without  ventilation, 
virtually  every  time  we  intubate  a 
child,  we  initiate  mechanical  ventila- 
tion. But  patients  undergoing  laryngo- 
tracheoplasty  at  Cincinnati  Children's 
Hospital  are  allowed  to  be  ambulatory 
postoperatively  with  nothing  but  an 
artificial  "nose"  attached  to  the  endo- 
tracheal tube.  There  is  a  difference  in 
practice  without  any  apparent  detri- 
mental effects. 

Hess:  What  about  the  issue  of  neo- 
nates? It  used  to  be  taught  that  if  a 
neonate  is  intubated,  they  need  to  have 
CPAP  applied  to  the  airway  to  main- 
tain their  functional  residual  capacity 
and  so  forth.  Is  that  still  common  think- 
ing among  neonatologists? 

Thompson:  Absolutely.  Surfactant 
deficiency  in  infants  with  hyaline 
membrane  disease  (infant  respiratory 
distress  syndrome)  results  in  diffuse 
atelectasis,  hypoxemia,  and  tnarkedly 
increased  work  of  breathing.  The  nat- 
ural defense  is  "grunting"  exhalation. 


which  is  effectively  spontaneous 
PEEP.  Intubation  without  end-expira- 
tory pressure  removes  this  defense  and 
allows  progressive  atelectasis.  In  ad- 
dition, chest  wall  mechanics  further 
predispose  the  young  infant  to  low 
functional  residual  capacity.  Older  in- 
fants and  children  with  lung  disease 
that  leads  to  secondary  surfactant  de- 
ficiency also  need  distending  expira- 
tory pressure. 

Hess:  So  if  it's  a  baby  who's  intu- 
bated because  of  an  upper  airway 
anomaly,  for  example,  they  don't  nec- 
essarily need  CPAP. 

Thompson:  As  1  indicated  earlier, 
the  value  of  distending  airway  pres- 
sure in  infants  extends  beyond  surfac- 
tant deficiency.  I  would  be  reluctant 
to  maintain  intubation  in  a  young  in- 
fant without  it.  However,  beyond  in- 
fancy, particularly  in  children  with 
healthy  lungs  and  primary  airway 
problems,  it  is  probably  acceptable  to 
intubate  without  providing  distending 
pressure,  and  in  some  there  may  be 
benefits  to  the  freedom  and  activity 
that  is  possible  when  the  child  is  not 
tethered  to  a  ventilator. 

Campbell:  You  presented  Bro- 
chard's  work  looking  at  the  work  of 
breathing  without  the  endotracheal 
tube.  1  would  like  to  refer  you  to  the 
paper  by  Ishaaya  in  the  1995  volume 
of  Chest,  where  they  recorded  a  3-fold 
increase  in  work  of  breathing  after  ex- 
tubation.'  In  1993,  Nathan  was  the  first 
author  of  a  paper  wherein  the  work  of 
breathing  was  observed  to  double  fol- 
lowing extubation."  In  our  experience 
in  Cincinnati'  in  patients  who  were  at 
high  risk  for  failure  after  extubation, 
we've  also  measured  a  2-fold  to  3-fold 
increase  in  work  of  breathing  follow- 
ing extubation.  So,  1  think  there  is  a 
patient  population  there  that's  at  risk 
for  increased  work  of  breathing.  And 
I  have  one  more  question.  Are  you  ad- 
vocating the  universal  application  of  this 
aspirating  endotracheal  tube,  or  is  it  on 
a  selective  basis? 


REFERENCES 

1 .  Ishaaya  AM,  Nathan  SD.  Belman  MJ.  Work 
of  breathing  after  extubation.  Chest  1995; 
107(1  ):2()4-209. 

2.  Nathan  SD.  Ishaaya  AM.  Koerner  SK.  Bel- 
man  MJ.  Prediction  of  minimal  pressure 
support  during  weaning  from  mechanical 
ventilation.  Chest  I99.^;l().^(4):  I  215- 
1219. 

^.  Davis  K  Jr.  Campbell  RS.  Johannignian 
JA.  Valenle  JF.  Branson  RD.  Changes  in 
respiratory  mechanics  after  tracheostomy. 
Arch  Surg  I999;I,U(  I  ):59-62. 

Hess:  We  are  not  using  it  currently, 
so  I  would  be  a  hypocrite  if  I  were  to 
recommend  anything  other  than  that.  I 
think  that  the  cost  benefit  has  not  con- 
clusively been  shown,  but  it's  certainly 
very  attractive. 

Campbell:  The  reason  I  asked  is 
because  of  the  fact  that  if  you  were  to 
require  the  procedure  of  reintubation, 
to  use  this  on  a  .selective  basis,  it  may 
overcome  the  benefit  of  its  use. 

Hess:  Exactly.  That's  the  point  that 
I  made  before.  You  have  to  use  it  on 
everybody.  You  can't,  in  selected  pa- 
tients, extubate  them  and  reintubate 
them  with  this,  because  that  also  in- 
creases the  ventilator-associated  pneu- 
monia rate. 

Durbin:  I'd  like  to  point  out  that  in 
the  2  papers  that  have  been  pub- 
lished,'" the  onset  of  ventilator-asso- 
ciated pneumonia  was  delayed.  How- 
ever, there  was  no  difference  in 
ultimate  patient  outcome  and,  there- 
fore, maybe  we're  dealing  with  a  meta- 
phenomenon,  anyway.  I  think  this 
gives  more  insight  into  the  pathogen- 
esis of  the  disease  process  than  it  does 
into  an  acceptable  universal  standard 
for  treatment.  I  personally  don't  think 
the  answer's  in  yet.  Does  anybody  here 
use  those  tubes  on  a  routine  basis?  Or 
at  all,  .selectively?  No  one  in  the  au- 
dience really  has  any  firsthand  expe- 
rience with  this  device,  despite  the  fact 
that  it's  been  around  for  about  3  or  4 
years.  It  is  manufactured  by  Mallinck- 
rodl  and  available  at  about  3  to  8  limes 


612 


Rf-.spiratory  Care  •  June  1999  Voi.  44  No  6 


Indications  for  Translaryngeal  Intubation 


the  cost  of  a  traditional  endotracheal 
tube.  I  have  seen  one,  and  it  is  stiffer, 
more  rigid,  and  less  flexible  than  a 
conventional  endotracheal  tube.  I 
wouldn't  encourage  people  to  leave 
this  conference  thinking  we  have  a  so- 
lution to  ventilator-associated  pneu- 
monia. We  have  a  proposed  suggestion 
that  people  need  to  become  comfortable 
with  and  understand,  but  I  don't  think 
we  have  a  solution  at  this  point  in  time. 

REFERENCES 

1 .  Kollef  MH,  Silver  P.  Ventilator-associated 
pneumonia:  an  update  for  clinicians.  Re- 
spirCare  1995;40(1 1):1 130-1 140. 

2.  Valles  J,  Artigas  A,  Rello  J,  Bonsoms  N, 
Fontanals  D.  Blanch  L,  et  al.  Continuous 
aspiration  of  subglottic  secretions  in  pre- 
venting ventilator-associated  pneumonia. 
Ann  Intern  Med  1995;  122(3);  179-1 86. 

Ritz:  To  answer  Charlie  Durbin's 
question,  I  have  seen  that  done,  but 
not  with  that  endotracheal  tube,  but 
instead  with  the  Pitt  talking  tracheal 
tube,  which  has  been  around  for  years. 
I  used  them  at  one  time,  with  Dr  Pier- 
son,  to  resolve  a  chronic  aspiration 
problem.  Instead  of  using  gas  flow  into 
the  talking  port,  using  the  suction  to 
clear  the  secretions  that  collected 
above  the  tracheostomy  tube  cuff. 

Bishop:  You've  taken  the  5  indica- 
tions for  intubation,  and  I  think  ap- 
propriately pointed  out  that,  probably 
with  the  exception  of  establishing  an 
airway  in  someone  with  obstruction 
or  impending  obstruction,  most  of  the 
others  things  can  be  managed,  at  least 
short  term,  without  intubation.  I'd  like 
to  point  out  that  that  will  become  im- 
portant tomorrow  when  I  talk  about 
who  should  intubate.  I  think  you've 
made  the  appropriate  point  that  only 
rarely  is  intubation  actually  an  emer- 
gency if  you're  skilled  with  a  bag  and 
mask  and  suction. 

Stauffer:  Wouldn't  "tube-associat- 
ed" pneumonia  be  a  better  term  than 
"ventilator-associated"  pneumonia? 


How  did  the  term,  "ventilator-associ- 
ated pneumonia,"  get  into  our  litera- 
ture? Do  patients  with  noninvasive 
mask  ventilation  develop  pneumonia 
with  any  frequency  close  to  that  of 
ventilator-associated  pneumonia? 

Hess:  Both  good  questions.  I  think 
it  became  known  as  ventilator-associ- 
ated pneumonia  (getting  back  to  Dave 
Pierson's  point)  because  when  we  put 
in  the  endotracheal  tube,  we  hook  it  to 
a  ventilator.  Regarding  invasive  ver- 
sus noninvasive  ventilation,  a  recent 
paper  by  Nava'  showed  that  noninva- 
sively  ventilated  patients  have  a  lower 
rate  of  ventilator-associated  pneumo- 
nia than  invasively  ventilated  patients. 


REFERENCE 

1.  Nava  S.  Ambrosino  N.  Clini  E.  Prate  M. 
Orlando  G.  Vitacca  M.  et  al.  Noninvasive 
mechanical  ventilation  in  the  weaning  of 
patients  with  respiratory  failure  due  to 
chronic  obstructive  pulmonary  disease:  a 
randomized,  controlled  trial.  Ann  Intern 
Med  1998;128(9):721-728. 


Branson:  Dean,  what  about  the 
whole  issue  of  the  endotracheal  tube 
as  an  impediment  to  the  work  of 
breathing,  but  also  as  an  impediment 
to  control  of  the  ventilator?  Several 
papers  have  indicated  that  adding  pres- 
sure support  in  patients  with  chronic 
obstructive  pulmonary  disease,  in  or- 
der to  overcome  the  work  of  breath- 
ing, actually  results  in  neuromechani- 
cal  dyssynchrony  because  the  patient 
can't  exhale  the  volume  you've  just 
delivered  with  pressure  support  before 
they  want  to  take  the  next  breath.'  ■* 
We  talked  about  this  at  the  American 
College  of  Chest  Physicians  confer- 
ence. Do  you  think  there's  going  to  be 
a  role  for  a  mode  like  automatic  tube 
compensation?  If  Mike  Banner  were 
here,  I'm  sure  he  would  tell  us  we 
have  to  control  tracheal  airway  pres- 
sure, not  proximal  airway  pressure.  Do 
you  have  an  opinion  about  where  we '  re 
going  to  go  with  that? 


REFERENCES 

1.  Leung  P.  Jubran  A.  Tobin  MJ.  Compari- 
son of  assisted  ventilator  modes  on  trig- 
gering, patient  effort,  and  dyspnea.  Am  J 
Respir  Crit  Care  Med  1997;L').')(6):1940- 
1948. 

2.  Jubran  A,  Van  de  Graaff  WB.  Tobin  MJ. 
Variability  of  patient-ventilator  interaction 
with  pressure  support  ventilation  in  pa- 
tients with  chronic  obstructive  pulmonary 
disease.  Am  J  Respir  Crit  Care  Med  1995; 
152(1):  129-1 -36. 

3.  Fabry  B.  Haberthur  C.  Zappe  D.  Guttmann 
J.  Kuhlen  R,  Stocker  R.  Breathing  pattern 
and  additional  work  of  breathing  in  spon- 
taneously breathing  patients  with  different 
ventilatory  demands  during  inspiratory 
pressure  support  and  automatic  tube  com- 
pensation. Intensive  Care  Med  I997;23(5): 
545-552. 

4.  Fabry  B,  Guttmann  J.  Eberhard  L,  Bauer 
T.  Haberthur  C.  Wolff  G.  An  analysis  of 
desynchronization  between  the  spontane- 
ously breathing  patient  and  ventilator  dur- 
ing inspiratory  pressure  support.  Chest 
1995;  1 07(5):  1387-1389. 

Hess:  Well,  you  heard  my  opinion  a 
little  bit  at  that  conference,  where  I 
was  asked  to  talk  about  automatic  tube 
compensation,  and  I've  talked  a  little 
bit  about  it  in  my  paper.  I'm  not  sure 
what  the  role  for  that  mode  is  going  to 
be,  because,  as  I  pointed  out  in  my 
talk,  I'm  not  sure  how  important  the 
resistance  to  the  endotracheal  tube  is. 
Maybe  it  is  as  important  as  I  once 
thought;  maybe  it's  even  less  impor- 
tant than  I  now  think  it  is.  If  resistance 
through  the  endotracheal  tube  doesn't 
make  very  much  difference  in  out- 
come, as  I  think  the  Esteban  study' 
and  the  Straus  study'  might  suggest 
then  there's  going  to  be  a  limited  role 
for  automatic  tube  compensation. 

Maybe  the  role  for  that  is  going  to  be 
in  neonatal  and  pediatric  patients  who 
require  the  very  small  endotracheal  tube. 
It  may  not  be  for  the  adult  patient  with 
an  8-8.5  mm  endotracheal  tube. 

REFERENCES 

1 .  Esteban  A.  Alia  1.  Gordo  F,  Fernandez  R. 
Solsona  JF.  Vallverdu  I.  et  al.  Extubation 
outcome  after  spontaneous  breathing  trials 
with  T-lube  or  pressure  support  ventila- 
tion. The  Spanish  Lung  Failure  Collabo- 
rative Group.  Am  J  Respir  Crit  Care  Med 


Respiratory  Care  •  June  1999  Vol  44  No  6 


613 


iNnic'ATioNs  lOR  Tkanslaryngeal  Intubation 


1997:156(2  Pi  1):459^65.  Published  vr- 
niliiiii  (ippeuis  ill  Am  .1  Ri'Sjiir  Ciil  Cciie 
MctI  IW7:l56lf)):2()2,S. 
2.  Siraiis  C.  I.oiiis  B.  Is;ihcy  I),  Ix'niairc  I-. 
Harf  A.  Brochard  I..  Contiihulioii  o\  ihc 
endotracheal  tube  and  the  upper  airway  to 
breathini!  workloail.  Am  J  Respir  Crit  Care 
Med  I9ys;l57(l):2.^   .^0. 

Heffner:  When  we  look  at  thai  type 
ofhtcrature.  I  wonder  if  we  lose  some 
important  rindings  in  subgroups.  If  we 
look  at  2  groups  of  patients  and  find 
that  there's  no  difference  of  outcome, 
1  wonder  if  we're  asking  tlie  c|ueslioiis 
about  the  efficacy  of  those  2  interven- 
tions in  general  groups  of  patients  who 
are  approaching  weanability  as  op- 
posed to  looking  at  a  subgroup,  and 
that  subgroup  might  include  the  very 


difficult-to-wean  patient,  the  patient 
who  is  very  marginal,  perhaps  with  a 
marginal  decrease  of  an  encumbrance, 
such  as  airway  resistance,  who  might 
achieve  a  better  outcome.  I  think  those 
studies  have  not  yet  been  done. 

Hess:  Your  point's  well  taken. 
Those  are  also  the  most  difficult  pa- 
tients to  study  and  to  get  any  kind  of 
an  endpoint  that's  reportable.  That's 
difficult  maybe,  but  your  point  cer- 
tainly is  well  taken. 

Heffner:  When  we  consider  those 
studies,  we  might  realize  that  the  con- 
clusions are  not  generalizable  to  all 
patient  populations. 


Hess:     Good  point. 


Campbell:  I'll  carry  that  one  step 
further  and  add  another  point  about 
putting  a  ventilator  on  every  patient 
we  intubate,  and  that  is  the  fear  that 
all  tachypnea  is  bad.  There  are  a  lot  of 
patients  in  whom  we  apply  pressure 
support  or  mechanical  ventilation  in 
an  attempt  to  decrease  work  of  breath- 
ing, but  we  continue  to  see  the  patient 
having  signs  of  increased  work  of 
breathing,  such  as  tachypnea  or  rapid 
shallow  breathing.  There  are  a  lot  of 
patients  who  can  be  tachypnic  but  who 
do  not  require  mechanical  ventilation 
durins  that  time. 


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Respiratory  Care  •  June  1999  Vol  44  No  6 


Orotracheal  Intubation  Outside  the  Operating  Room:  Anatomic 

Considerations  and  Techniques 


William  E  Hurford  MD 


Introduction 

Normal  Adult  Upper  Airway  Anatomy 

The  Nasopliarynx 

Tiie  Oral  Cavity  and  Oropharynx 

The  Larynx 

The  Trachea 
Orotracheal  Intubation  Techniques 

Preparation 

Direct  Laryngoscopy  and  Orotracheal  Intubation 

Nasotracheal  Intubation 
Anesthesia,  Sedation,  and  Neuromuscular  Blockade  for 
Endotracheal  Intubation 

Awake  Intubation 

Intravenous  Sedation 

Anesthesia  and  Neuromuscular  Blockade 
Alternative  Intubation  Techniques 

Fiberoptic  Intubation 

Light  Wand 

Digital  Intubation 
Verification  of  Intubation 

End-Tidal  Carbon  Dioxide 

Physical  Signs  and  Symptoms 
Complications  of  Intubation 
Immediate  Care  of  the  Patient  after  Intubation 

[Respir  Care  1999;44(6):6 15-626]  Key  words:  orotracheal  intubation,  endo- 
tracheal intubation,  nasotracheal  intubation,  artificial  airways,  intubation  tech- 
niques, airway  management,  airway  anatomy. 


Introduction 

This  review  is  specifically  written  as  a  brief  introduc- 
tion to  airway  anatomy  and  orotracheal  intubation  tech- 
niques for  those  who  must  manage  a  patient's  airway, 
usually  under  emergency  conditions,  outside  the  controlled 


William  E  Hurford  MD  is  affiliated  with  the  Department  of  Anaesthesia 
and  Critical  Care,  Massachusetts  General  Hospital,  and  Harvard  Medical 
School,  Boston,  Ma.ssachusetts. 

Correspondence:  William  E  Hurford  MD,  Department  of  Anaesthesia 
and  Critical  Care.  Massachusetts  General  Hospital.  Boston  MA  02 1 1 4. 
E-mail:  hurford@etherdome.mgh.harvard.edu. 


environment  of  an  operating  room.  A  review  of  normal 
upper  airway  anatomy  emphasizes  how  anatomic  features 
may  affect  successful  endotracheal  intubation.  Approaches 
to  orotracheal  intubation  are  discussed,  along  with  an  in- 
troduction to  the  use  of  sedatives  and  neuromuscular  block- 
ing agents.  The  reader  is  referred  to  the  excellent  review 
by  Dr  James  T  Roberts  for  detailed  discussions  of  endo- 
tracheal intubation  techniques.' 

Normal  Adult  Upper  Airway  Anatomy 

A  practical  knowledge  of  upper  airway  anatomy  is  crit- 
ical to  developing  successful  endotracheal  intubation  tech- 
niques. The  upper  airway  consists  of  the  air  passages  ex- 


Respiratory  Care  •  June  1999  Vol  44  No  6 


615 


Orotracheal  Intubation  Outside  the  Operating  Room 


Nasal  cavity 
Nasopharynx 

Soft  palate 
Oropharynx 

Laryngopharynx 


Nares 


Base  of  tongue 

Hyoid 

Vallecula 

Epiglottis 


Glottis 

Trachea 

Esophagus 


Fig.  1.  Schematic  diagram  of  the  upper  airway.  (From  Reference 
19,  with  permission.) 


tending  from  the  nares  and  mouth  to  the  trachea.  The 
lower  airways  consist  of  the  trachea,  bronchi,  and  alveoli. 
The  upper  airway  (Fig.  I )  is  divided  into: 

1 .  The  nasopharynx,  consisting  of  the  nasal  cavity,  sep- 
tum, turbinates,  and  adenoids, 

2.  The  oropharynx,  consisting  of  the  oral  cavity,  includ- 
ing the  teeth  and  tongue,  and 

3.  The  pharnynx,  which  includes  the  tonsils,  uvula,  and 
epiglottis. 

The  epiglottis  separates  the  larynx  (leading  to  the  tra- 
chea) from  the  hypopharynx  (leading  to  the  esophagus). - 

The  Nasopharynx 

The  nasal  passages  warm  and  humidify  inhaled  air.  En- 
dotracheal intubation  bypasses  these  important  functions. 
The  2  nasal  passages  are  divided  by  the  nasal  septum,  and 
are  covered  by  a  mucosa  with  a  rich  blood  supply.  The 
mucosa  is  easily  injured  during  nasotracheal  intubation 
and  can  bleed  profusely.  Its  vascular  supply  is  derived 
from  the  maxillary  artery  (which  is  a  branch  of  the  exter- 
nal carotid  artery),  and  the  anterior  ethmoid  artery  (which 
is  a  branch  of  the  ophthalmic  artery).  Sensory  innervation 
is  mostly  from  the  pterygopalatine  branches  of  the  maxil- 
lary division  of  the  trigeminal  nerve  (cranial  nerve  V). 
Trigeminal  pain,  like  toothaches,  can  be  excruciating.  Com- 


plete topical  anesthesia  of  the  nasal  mucosa  is  necessary 
prior  to  nasal  intubation.-  Inflammation,  infection,  or  the 
presence  of  a  nasotracheal  or  nasogastric  tube  can  cause 
nasal  mucosal  edema.  The  edema  can  completely  occlude 
the  nasal  passage  and  block  drainage  of  the  paranasal  si- 
nuses, which  may  lead  to  sinusitis  and  spread  of  infection 
via  venous  drainage  into  the  dural  venous  sinuses.  The  use 
of  topical  vasoconstrictors,  such  as  phenylephrine  and 
oxymetazoline,  may  shrink  edematous  mucosa  and  reduce 
the  extent  of  edema  and  the  risk  of  bleeding. 

The  Oral  Cavity  and  Oropharynx 

The  oral  cavity  has  4  sides  and  is  in  continuity  with  the 
oropharynx.  The  roof  is  composed  of  the  hard  and  soft 
palate,  which  assists  in  closing  off  the  nasal  cavity  during 
swallowing  and  helps  maintain  pharyngeal  patency  during 
breathing.  The  faucial  pillars  form  the  border  between  the 
oral  cavity  and  the  oropharynx  and  are  composed  of  2 
muscles  (the  palatoglossus  and  palatopharyngeus),  which 
tense  the  soft  palate.  The  tongue  and  mandible  form  the 
floor  of  the  mouth.  The  muscles  of  the  tongue  are  inner- 
vated by  the  hypoglossal  nerve  (cranial  nerve  XII).  Sen- 
sory innervation  of  the  tongue  is  complex  and  is  derived 
from  the  mandibular  division  of  the  trigeminal  nerve  (cra- 
nial nerve  V),  the  facial  nerve  (cranial  nerve  VII),  and  the 
glossopharyngeal  nerve  (cranial  nerve  IX). 

Mouth  opening  depends  on  proper  function  of  the  tem- 
poromandibular joint,  which  is  the  only  movable  (diar- 
throtic)  joint  in  the  head.  Its  motion  may  be  limited  by  pain 
(which  can  be  ameliorated  by  anesthetic  agents),  or  by 
arthritis  or  fibrosis  (which  is  unaffected  by  anesthesia  or 
muscle  relaxants).  Reduced  mobility  of  the  temporoman- 
dibular joint  can  make  direct  laryngoscopy  impossible. 
During  wide  mouth-opening,  the  mandible  can  be  dislo- 
cated anteriorly  into  the  infratemporal  fossa.  Reduction  is 
accomplished  by  depressing  the  jaw  to  overcome  muscular 
traction,  and  moving  it  posteriorly  back  into  place. - 

The  lateral  walls  of  the  oral  cavity  are  composed  of  the 
buccal  mucosa  and  teeth.  While  the  teeth  can  help  form  a 
natural  oral  airway  during  mask  ventilation,  protuberant 
teeth  can  interfere  with  direct  laryngoscopy.  Obviously, 
care  should  be  taken  to  avoid  damage  or  dislodgment  of 
teeth,  caps,  or  permanent  prosthetic  dental  devices  during 
intubation  attempts.  Removable  appliances  should  be  taken 
out  and  safely  stored  prior  to  mask  ventilation  or  laryn- 
goscopy. 

The  nasal  and  oral  cavities  open  into  the  nasopharynx 
and  oropharynx,  respectively,  which  are  in  continuity  with 
the  hypopharynx.  The  hypopharynx  extends  to  the  esoph- 
agus and  epiglottis.  The  valleculae  are  between  the  median 
and  lateral  glossoepiglottic  folds,  which  represent  liga- 
mentous attachments  between  the  pharynx  and  the  base  of 
the  tongue.  The  hyoepiglottic  ligament  joins  the  epiglottis 


616 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Orotracheal  Intubation  Outside  the  Operating  Room 


Epiglottis 


Hyoid 
bone 

Thyrotiyoid 
membrane 


Thyroid 
cartilage 


Cricothyroid 
membrane 
Cricoid  ring 

Tracheal  ring 


Fig.  2.  Anatomy  of  the  larynx.  Lateral  view  (left)  and  anterior  view 
(right)  show  the  cartilaginous  and  membranous  structures  of  the 
larynx.  (From  Reference  19,  with  permission.) 


and  the  hyoid  bone.  During  direct  laryngoscopy  with  a 
Macintosh  blade,  the  tip  of  the  blade  is  placed  in  the 
valleculae  and  elevates  the  epiglottis  by  providing  traction 
on  the  hyoepiglottic  ligament. 

The  Larynx 

The  larynx  is  located  at  the  level  of  the  fourth  through 
sixth  cervical  vertebrae.  It  serves  in  the  functions  of  air- 
way protection,  ventilation,  and  phonation.  The  larynx  is 
an  intricate  structure  composed  of  cartilage,  ligaments, 
and  muscles  (Figs.  2  and  3).  There  are  9  cartilages  in  the 
larynx:  3  unpaired  (the  thyroid  cartilage,  the  cricoid  car- 
tilage, and  the  epiglottis),  and  3  paired  (the  arytenoid  car- 
tilages, the  small  corniculate  cartilages,  and  the  cuneiform 
cartilages).''  The  shield-shaped  thyroid  cartilage  is  the  larg- 
est laryngeal  cartilage  and  forms  the  base  for  the  larynx. 
The  laryngeal  prominence  (Adam's  apple)  is  its  midline 
anterior  protuberance.  The  cricoid  cartilage,  located  infe- 
rior to  the  thyroid  cartilage,  is  the  only  complete  cartilag- 
inous ring  in  the  respiratory  system.  It  is  the  narrowest  part 
of  the  airway  in  the  pediatric  patient.  Posterior  pressure  on 
the  cricoid  cartilage  (the  Sellick  maneuver)  can  compress 
the  esophagus  against  the  sixth  cervical  vertebra  and  re- 
duce the  risk  of  passive  reflux  of  gastric  contents  into  the 
airway  during  intubation.-*  It  is  important  to  note  that  per- 
sistent use  of  the  Sellick  maneuver  during  active  vomiting 
is  ineffective  and  could  produce  esophageal  trauma.  The 
cricothyroid  membrane  connects  the  thyroid  cartilage,  the 
arytenoids,  and  the  cricoid.  It  measures  approximately  0.9 
cm  X  3.0  cm  in  the  adult  and  is  quite  thin,  with  no  major 
vessels  in  the  midline.  These  anatomic  features  make  the 
cricothyroid  membrane  an  attractive  site  for  emergency 
surgical  access  to  the  airway  (cricothyrotomy).''  The  epi- 


Fig.  3.  Intrinsic  muscles  of  the  larynx  (seen  from  above)  and  (in 
parentheses)  their  functions:  a  =  vocal  cord;  b  =  cricothyroids 
(tense  vocal  cords);  c  =  thyroarytenoids  (main  function  is  to  relax 
vocal  cords;  the  lateral  portion  adducts  arytenoids);  d  =  lateral 
cricoarytenoids  (close  glottis);  e  =  transverse  arytenoids  (close 
glottis);  f  =  oblique  arytenoids  (close  glottis);  g  =  posterior  crico- 
arytenoids (open  glottis);  h  =  thyroid  cartilage;  i  =  arytenoid  car- 
tilage; j  =  cuneiform  cartilage.  (From  Reference  1,  with  permis- 
sion.) 


glottis  is  the  uppermost  portion  of  the  larynx.  It  is  a  tear- 
shaped  structure  (oinega-shaped  in  children)  and  is  at- 
tached to  the  posterior  border  of  the  thyroid  cartilage  by 
the  thyroepiglottic  ligament.  The  paired  arytenoid  carti- 
lages articulate  with  the  posterosuperior  aspect  of  the  cri- 
coid cartilage.  The  vocal  ligaments  stretch  between  the 
anterior  process  of  each  arytenoid  and  the  thyroid  carti- 
lage. 

The  intrinsic  laryngeal  muscles  are  of  2  types:  ( I )  mus- 
cles that  open  and  close  the  glottis,  and  (2)  those  that 
control  the  tension  of  the  vocal  ligaments  (see  Fig.  3). 
Muscles  that  open  and  close  the  glottis  include  the  lateral 
cricoarytenoids  (adduction,  moving  the  vocal  cords  closer 
together),  the  posterior  cricoarytenoids  (abduction,  widen- 
ing the  space  between  the  vocal  ligaments),  and  the  trans- 
verse and  oblique  arytenoids  (adduction).  Muscles  that 
control  the  tension  of  the  vocal  ligaments  include  the  cri- 
cothyroid, vocalis,  and  thyroarytenoid.  The  motor  inner- 
vation of  all  the  intrinsic  muscles  of  the  larynx  except  the 
cricothyroid  is  supplied  by  the  recurrent  laryngeal  nerve,  a 
branch  of  the  vagus  nerve  (cranial  nerve  X).  The  crico- 
thyroid muscle  receives  motor  innervation  from  the  exter- 
nal branch  of  the  superior  laryngeal  nerve,  which  is  also  a 
branch  of  the  vagus  nerve. 

Sensory  innervation  to  the  posterior  one  third  of  the 
tongue  and  the  oropharynx,  from  its  junction  with  the 
nasopharynx  to  its  junction  with  the  pharynx  and  esopha- 


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6!7 


Orotracheal  Intubation  Outside  the  Operating  Room 


gus,  is  supplied  by  the  glossopiiaryngeal  nerve  (cranial 
nerve  IX).  The  internal  branch  of  the  superior  laryngeal 
nerve  provides  sensation  for  the  mucosa  from  the  epiglot- 
tis to  and  including  the  vocal  cords.  The  recurrent  laryn- 
geal nerve  provides  sensory  innervation  to  the  mucosa 
below  the  vocal  cords  and  the  trachea.  Mucosal  anesthesia 
can  be  provided  by  topical  application  of  local  anesthetics. 
In  addition,  the  glossopharyngeal  nerve  can  be  blocked  by 
injection  of  local  anesthetic  underneath  the  palatoglossal 
arch  adjacent  to  the  tongue.  The  superior  laryngeal  nerve 
can  be  blocked  by  the  topical  application  of  local  anes- 
thetic in  the  pyriform  recesses  lateral  to  the  larynx. 

The  Trachea 

The  trachea  is  a  fibromuscular  tube,  approximately 
10-12  cm  in  length  in  the  adult,  with  a  diameter  of  ap- 
proximately 20  mm.  It  is  supported  by  approximately  16  to 
20  U-shaped  cartilages.  It  enters  the  chest  cavity  at  the 
superior  mediastinum  and  bifurcates  (at  the  sternal  angle) 
at  the  lower  border  of  the  fourth  thoracic  vertebra. 

Orotracheal  Intubation  Techniques 

Endotracheal  intubation  is  required  to  provide  a  patent 
airway  when  patients  are  at  risk  for  aspiration,  when  air- 
way maintenance  by  mask  is  difficult,  and  for  prolonged 
mechanical  ventilation.  It  is  also  required  for  certain  sur- 
gical procedures  (eg,  head/neck,  intrathoracic,  or  intraab- 
dominal procedures).  Outside  of  the  operating  room,  en- 
dotracheal intubation  is  often  an  emergency  procedure, 
involves  intubation  of  the  awake  patient  in  respiratory  dis- 
tress, and  can  be  especially  challenging  in  situations  where 
certain  of  the  usual  aids  to  intubation  are  absent  (eg,  in  an 
ambulance,  aircraft,  or  other  field  environment).  These 
situations  are  frequently  stressful,  the  position  of  the  pa- 
tient and  the  operator  are  awkward,  the  patient  is  usually 
quite  ill,  and  therefore  the  intubation  success  rate  is  re- 
duced and  the  risk  of  complications  increased.^  It  is  nec- 
essary to  employ  a  systematic  approach  in  such  situations, 
and  to  maintain  a  high  index  of  suspicion  that  the  endo- 
tracheal tube  might  be  malpositioned. 

Preparation 

1.  Be  calm.  If  the  patient  is  awake,  breathing,  and  re- 
ceiving supplemental  oxygen,  there  is  almost  always  time 
for  sufficient  preparation.  Do  not  allow  haste  to  result  in 
poor  practice.  A  calm,  collected  approach  with  efficient 
but  complete  preparation  is  best.  The  following  steps  can 
be  accomplished  virtually  simultaneously  if  there  are  other 
people  available  to  help. 

2.  Brina  all  necessary  intubation  equipment,  including 
drugs  that  may  not  be  readily  available,  to  the  patient's 


Table  I .       Suggested  Contents  of  an  Emergency  Intubation  Bag 


Equipment 


Drugs 


Intravenous  catheters  (14-22  g) 
Laryngoscope  blades:  Macintosh 

2,3,4;  Miller  0,1,2,3 
Endotracheal  tubes  (3-8  mm  ID) 
10  mL  syringes 
Magill  forceps 
Colorimetric  end-tidal  CO, 

detectors 
Nasal  airways 
Oral  airways 
Tape 

Yankauer  suction  catheters 
Tube  changers 
Guide  wires 
Cotton  swabs 
Nasogastric  tubes 
Jet  ventilator 


Atropine 
Cisatracurium 

Ephedrine  ; 

Epinephrine 
Esmolol 

Ethyl  aminobenzoate 
(Hurricaine)  spray 
Etomidate 
Glycopyrrolate 
Labetalol 

Lidocaine  ( I  and  4%) 
Lidocaine  ointment 
Midazolam 
Naloxone  (Narcan) 
Oxymetazoline  (Afrin)  spray 
Pancuronium 
Phenylephrine 

Phenylephrine/lidocaine  spray 
Propofol 
Propranolol 
Saline 

Succinylcholine 
Surgi-lube 
Vi.scous  lidocaine 


bedside.  All  the  required  equipment  may  be  easily  stored 
and  transported  in  a  small  box  or  bag  specifically  designed 
for  the  purpose.  Suggested  contents  for  such  an  emergency 
intubation  bag  are  listed  in  Table  1. 

3.  Review  the  patient's  history.  This  can  be  done  con- 
currently with  other  tasks.  It  should  include  a  quick  as- 
sessment of  the  patient's  respiratory  and  cardiac  status, 
and  a  decision  regarding  the  degree  of  urgency  of  endo- 
tracheal intubation.  Review  any  available  prior  records  of 
general  anesthesia  or  endotracheal  intubation.  It  is  ex- 
tremely helpful  to  know  the  degree  of  difficulty  of  the 
patient's  prior  intubations.  The  prior  history  is  not  en- 
tirely reliable  because  many  other  factors  (eg,  airway 
edema,  trauma,  and  hemoptysis)  may  have  intervened. 
A  history  of  recent  ingestion  of  food  or  liquids  is  of 
interest.  Nevertheless,  always  assume  that  the  patient 
has  a  full  stomach. 

4.  Position  the  patient.  In  the  supine  position,  the  pa- 
tient's pharyngeal  and  laryngeal  axes  are  offset,  making  a 
good  view  of  the  glottis  extremely  difficult  during  direct 
laryngoscopy  (Fig.  4).  Positioning  the  patient  in  the  so- 
called  "sniffing"  position,  with  the  occiput  elevated  by 
pads  or  folded  blankets  and  the  head  in  extension,  aligns 
the  oral,  pharyngeal,  and  laryngeal  axes  so  that  the  path- 
way from  the  lips  to  the  glottis  is  nearly  a  straight  line 
(Fig.  5).  If  the  patient  is  in  a  bed  or  stretcher,  he  or  she 
should  be  moved  to  the  head  of  the  bed  so  that  the  operator 


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Orotracheal  Intubation  Outsidi;  thi-:  Oi'iiRAiiNO  Room 


Laryngeal  axis 


Oral  axis 


Pharyngeal  •-- 
axis 


Tracheal 
lumen 


Esophagus 


Fig.  4.  Anatomic  relationships  for  laryngoscopy  and  endotracheal 
intubation.  (From  Reference  3,  with  permission.) 


Pharyngeal-laryngeal 
axis 


Fig.  5.  The  sniffing  position  aligns  the  pharyngeal  and  laryngeal 
axes.  (From  Reference  3,  with  permission.) 


is  not  bending  and  reaching  in  order  to  manage  the  pa- 
tient's airway.  Adequate  space  at  the  head  of  the  bed  is 
necessary.  Pull  the  bed  away  from  the  wall  if  necessary,  so 
that  there  is  plenty  of  room  to  maneuver.  If  there  is  a 
headboard  on  the  bed.  remove  it.  Adjust  the  height  of  the 
bed  so  that  the  patient's  head  is  at  your  mid-chest  level. 

Sometimes  intubation  must  take  place  in  less  than  ideal 
locations,  and  proper  positioning  of  the  head  and  neck  are 
even  more  critical  in  this  circumstance.  For  example,  the 
patient  may  be  lying  on  the  ground  or  floor.  For  such  a 
patient,  the  success  rate  for  intubation  appears  to  be  slightly 
higher  when  the  operator  lies  in  the  left  lateral  decubitus 
position  at  the  patient's  head,  rather  than  kneeling  or  strad- 
dling the  patient.'** 

The  trauma  patient  presents  special  challenges."  All  pa- 
tients with  multiple  trauma,  head,  or  facial  injury  must  be 
presumed  to  have  a  cervical  spine  injury  until  excluded  by 
a  full  evaluation.  In  such  patients,  excessive  motion  of  the 
spine  may  produce  or  exacerbate  a  spinal  cord  injury. 
During  airway  manipulations,  an  assistant  should  stabilize 
the  head  and  neck  in  a  neutral  position  by  maintaining 
in-line  cervical  traction.'"  Experimental  and  clinical  stud- 
ies have  indicated  that  orotracheal  intubation  causes  no 
more  cervical  displacement  or  neurologic  sequelae  than 
nasotracheal  intubation."'-  The  greatest  cervical  displace- 
ment appears  to  occur  during  bag  and  mask  ventilation. 
Administration  of  anesthesia  and  a  neuromuscular  block- 
ing agent  may  be  necessary  to  avoid  excessive  motion. 


Fig.  6.  The  laryngoscope  blade  is  divided  into  the  spatula  (S),  the 
flange  (F),  and  the  tip  (T).  (From  Reference  14,  with  permission.) 


."S.  Check  iluit  siuiion  is  avdiUihlc  in  the  form  of  a 
Yankauer  or  "■tonsil  lip"  suction  device.  Check  to  ensure 
that  the  suction  is  functioning  properly  prior  to  your  first 
attempt  at  laryngoscopy. 

6.  Oxyi'ciuilc  ilic  piiticnt.  Regardless  of  the  type  of  ox- 
ygen therapy  administered  to  the  patient  prior  to  the  de- 
cision to  intubate,  administer  100%  oxygen  via  a  tight 
fitting  mask  and  self-inflating  rcsuscitalor  bag  prior  to  any 
attempt  at  intubation.  Most  patients  requiring  intubation 
outside  of  the  operating  room  are  in  respiratory  distress 
and  hypoxemic.  Thus,  they  will  not  tolerate  even  a  short 
period  of  breathing  room  air. 

7.  Estdhlish  intravenous  access.  The  intravenous  line 
should  be  freely  running  (not  cajiped)  and  its  adequacy 
demonstrated  prior  to  laryngoscopy.  In  cases  of  cardiac 
arrest,  in  which  the  administration  of  sedatives  and  para- 
lytic agents  are.  obviously,  imnecessary,  intubation  can 
precede  the  establishment  of  adequate  intravenous  access; 
the  endotracheal  tube  can  be  used  as  an  alternative  route  of 
drug  administration." 

Direct  Larynj>o.scopy  and  Orotracheal  Inliihatiun 

Intubation  is  usually  performed  with  the  assistance  of  a 
laryngoscope.  The  laryngoscope  is  composed  of  a  handle 
(which  usually  contains  the  batteries  for  the  light  source), 
and  a  laryngoscope  blade  (which  usually  contains  a  light 
bulb  in  the  distal  third  of  the  blade).  Many  types  of  laryn- 
goscope blades  have  been  designed.'^  All  blades  have  3 
parts  in  common  (Fig.  6): 

1.  The  spatula,  which  moves  and  depresses  the  tongue 
and  mandible, 

2.  A  tlange  on  the  spatula,  which  holds  the  tongue  and 
soft  tissues  out  of  the  field  of  view,  and 

.3.  The  tip.  which  elevates  the  epiglottis.'^ 
The  Macintosh  and  Miller  blades  are  most  commonly 
used  (Fig.  7  A  and  B). 

The  Macintosh  blade  (see  Fig.  7A)  is  curved,  and  the  tip 
is  inserted  into  the  vallecula  (the  space  between  the  base  of 
the  tongue  and  the  pharyngeal  surface  of  the  epiglottis) 


Respiratory  Care  •  June  1999  Vol  44  No  6 


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Orotracheal  Intubation  Outside  the  Operating  Room 


Fig.  7.  Laryngoscopes  and  blades.  A.  Macintosh  blades  1  to  4, 
shown  with  standard,  pediatric,  and  short  handles;  B.  Miller  blades 
0  to  4,  shown  with  standard,  pediatric  and  short  handles.  (From 
Reference  15,  with  permission.) 


(Fig.  8).  Pressure  against  the  hyoepiglottic  ligament  ele- 
vates the  epiglottis  to  expose  the  larynx.  The  Macintosh 
blade  provides  a  good  view  of  the  oropharynx  and  hypo- 
pharynx,  thus  allowing  more  room  for  endotracheal  tube 
passage  with  diminished  epiglottic  trauma.  Macintosh 
blades  come  in  4  sizes  (called  1,  2,  3,  and  4);  most  adults 
require  a  Macintosh  No.  3  blade. 

The  Miller  blade  (see  Fig.  7B)  is  straight,  and  it  is 
passed  so  that  the  tip  lies  beneath  the  laryngeal  surface  of 
the  epiglottis  (Fig.  9).  The  epiglottis  is  then  lifted  to  ex- 
pose the  vocal  cords.  The  Miller  blade  allows  better  ex- 
posure of  the  glottic  opening  but  provides  a  smaller  pas- 
sageway through  the  oropharynx  and  hypopharynx.  Miller 
blades  also  come  in  4  sizes  (called  0,  1,2,  and  3);  most 
adults  requiring  a  Miller  No.  2  or  No.  3  blade. 

Test  for  the  proper  functioning  of  the  laryngoscope  prior 
to  its  use.  Then  hold  the  laryngo.scope  gently  near  the 
junction  between  the  handle  and  blade  with  the  tips  of  the 
fingers  of  the  left  hand.  Take  a  moment  to  progressively 
visualize  the  upcoming  laryngoscopy  in  your  mind.  Each 
structure  (lips,  teeth,  tongue,  tonsillar  pillar,  epiglottis,  glot- 
tis) should  be  progressively  identified  and  examined.  Ex- 


Fig.  8.  Placement  of  the  Macintosh  laryngoscope.  Note  that  the 
upper  teeth  and  maxilla  should  not  be  used  as  a  fulcrum  during 
laryngoscopy.  (From  Reference  3,  with  permission.) 


Blade  Placement 


Epiglottis 


Fig.  9.  Placement  of  the  Miller  laryngoscope.  (From  Reference  3, 
with  permission.) 


cessive  haste  to  identify  the  glottis  is  a  common  mistake  of 
the  beginner.  Visualization  of  airway  structures  is  also 
easier  if  you  maintain  a  sufficient  distance  between  your 
eyes  and  the  patient's  airway.  Crouching  too  close  to  the 
mouth  results  in  a  narrowed  visual  depth  of  field.  Experi- 
enced laryngoscopists  tend  to  stand  farther  away  from  the 
patient  than  do  novices."' 

Open  the  mouth  with  a  scissoring  motion  of  the  right 
thumb  and  index  finger,  then  insert  the  laryngoscope  into 
the  right  side  of  the  patient's  mouth,  avoiding  the  teeth 
while  sweeping  the  tongue  to  the  left.  Be  careful  not  to 
pinch  the  patient's  lip  between  the  blade  and  his  or  her 
teeth.  Advance  the  blade  to  expose  the  right  tonsillar  pil- 
lar, and  then  gently  redirect  the  blade  toward  the  midline 
and  advance  until  the  epiglottis  comes  into  view.  Lift  the 
tongue  and  pharyngeal  soft  tissues  to  expose  the  glottic 
opening  (Fig.  10).  The  direction  of  force  is  along  the  axis 


620 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Orotracheal  Intubation  Ouisidh  thk  OpiiRATiNc  Room 


Laryngoscope 
/      blade     \  ^Tongue 

Epiglottis  -^__;ii^ 

/  ^^I^|-^  Vocal  cord 

Arytenoid    .  AsVjK^^ 

cartilage    V^^^Sj^K  / 

Piriform 
sinus 

Fig.  10.  View  of  the  larynx  during  laryngoscopy  with  a  Macintosh 
blade.  (From  Reference  3,  with  permission.) 


of  the  laryngoscope  handle  as  it  is  lifted  away  from  the 
operator.  The  laryngoscope  blade  should  never  be  used  as 
a  lever  (see  Fig.  8),  with  the  upper  teeth  or  maxilla  as  the 
fulcrum,  because  this  action  might  damage  the  maxillary 
incisors  or  gingiva. 

The  selection  of  the  appropriate  si/.e  of  endotracheal 
tube  depends  on  the  patient's  age,  body  habitus,  and  indi- 
cation for  intubation.  A  7.0  mm  endotracheal  tube  is  a 
reasonable  choice  for  most  women,  and  an  8.0  mm  endo- 
tracheal tube  is  reasonable  for  most  men.  Prior  to  inser- 
tion, test  the  integrity  of  the  endotracheal  tube  cuff  and 
pilot  balloon  by  attaching  a  10  mL  syringe  to  the  one-way 
valve  of  the  pilot  balloon  and  then  briefly  inflating  the  cuff 
with  approximately  10  mL  of  air.  During  insertion,  hold 
the  endotracheal  tube  in  your  right  hand  (in  the  manner  in 
which  you  would  hold  a  pencil)  and  advance  it  through  the 
oral  cavity  from  the  right  corner  of  the  mouth,  and  then 
through  the  vocal  cords.  A  malleable  stylet  can  be  inserted 
through  the  tube  to  facilitate  placement.  The  end  of  the 
stylet  should  lie  at  least  I  cm  proximal  to  the  end  of  the 
endotracheal  tube  to  reduce  the  chance  of  injury  to  the 
airway.  Both  the  stylet  and  the  endotracheal  tube  can  be 
lubricated  with  a  water  soluble  lubricant  prior  to  insertion. 
The  tip  of  the  assembled  stylet  and  endotracheal  tube  can 
be  bent  anteriorly  into  a  gentle  "hockey  stick"  curve.  This 
helps  direct  the  tube  anteriorly  and  facilitates  placement 
when  visualization  of  the  glottis  is  poor.  If  visualization  of 
the  glottic  opening  is  incomplete,  it  may  be  necessary  to 
blindly  pass  the  endotracheal  tube  immediately  beneath 
the  epiglottis  and  into  the  trachea.  External  pressure  on  the 
cricoid  and/or  thyroid  cartilages  may  aid  in  visualization.'^ 
Place  the  proximal  end  of  the  endotracheal  tube  cuff  just 
below  the  vocal  cords,  and  note  the  markings  on  the  tube 
in  relation  to  the  patient's  incisors  or  lips.  In  the  average 
adult,  the  proper  depth  of  insertion,  measured  at  the  upper 
incisors,  is  approximately  21  cm  in  women  and  23  cm  in 
men."*  Inflate  the  cuff  just  to  the  point  of  obtaining  a  seal 
in  the  presence  of  20-.30  cm  H^O  positive  airway  pres- 
sure. The  tube  should  be  securely  fastened  with  tape,  pref- 
erably to  taut  skin  overlying  bony  structures.  An  entire 
attempt  at  endotracheal  intubation  should  take  no  longer 
than  30  seconds.'" 


Nasotracheal  Intubation 

Nasotracheal  intubation  is  sometimes  considered  because 
of  the  notion  that  a  "blind  nasal  intubation"  is  quick  and 
easy  to  perform.  This  is  not  true  for  an  inexperienced 
operator.  Nasotracheal  intubation  may  be  dangerous  in  this 
setting  because  of  the  lack  of  airway  control,  the  potential 
for  a  prolonged  period  of  low  inspired  oxygen  tensions 
during  manipulations  of  the  tube,  and  the  fact  that  a  nose- 
bleed at  this  time  would  be  disastrous.  If  nasotracheal 
intubation  is  contemplated,  it  should  be  performed  only 
after  orotracheal  intubation  has  been  accomplished,  and 
under  a  controlled  setting,  unless  the  operator  has  consid- 
erable experience  and  expertise  with  nasal  intubations.  Na- 
sotracheal intubation  should  not  be  performed  in  a  patient 
who  is  coagulopathic,  receiving  or  about  to  receive  anti- 
coagulants, or  about  to  receive  a  thrombolytic  agent.  The 
result  may  be  a  life-threatening  nosebleed. 

Anesthesia,  Sedation,  and  Neuromuscular  Blockade 
for  Endotracheal  Intubation 

In  most  cases,  it  is  preferable  to  intubate  the  patient  with 
as  little  attenuation  of  respiratory  drive  and  airway  re- 
flexes as  possible.  Thus,  intubation  should  be  attempted 
according  to  the  following  temporal  sequence: 

1.  Awake  intubation  with  topical  anesthetic, 

2.  Sedative  agents  only  if  necessary, 

3.  Paralysis  as  a  last  resort. 

There  are,  of  course,  exceptions  to  this  sequence.  The 
preoperative  cardiac  patient  who  is  in  cardiogenic  pulmo- 
nary edema  and  having  angina  may  require  general  anes- 
thesia to  blunt  the  hemodynamic  consequences  of  endo- 
tracheal intubation.  A  combative  multiple  trauma  patient 
may  require  anesthesia  and  paralysis  to  minimize  the  chance 
of  excessive  motion  exacerbating  a  spinal  cord  injury.  How- 
ever, these  are  exceptions.  The  3  most  important  axioms  to 
remember  when  contemplating  endotracheal  intubation  of 
a  patient  in  respiratory  distress  are 

1.  Expect  the  intubation  to  be  difficult  until  proven  oth- 
erwise. 

2.  The  patient  will  not  tolerate  even  short  periods  of 
apnea  or  hypoxia. 

3.  The  patient  //;  extremis  requires  much  less  anesthesia 
(and  frequently  none)  for  intubation,  compared  with 
a  healthy  patient. 

Awake  Intubation 

The  key  to  successful  intubation  of  an  awake  patient  is 
that  the  patient  is  informed  and  reassured.  Explain  each 
movement  in  advance,  in  a  calm,  reassuring  voice.  Pro- 
ceed deliberately.  Have  the  patient  open  his  or  her  mouth, 
and  apply  a  topical  anesthetic  spray  such  as  ethyl  amino- 


Respiratory  Care  •  June  1999  Vol  44  No  6 


62! 


Orotracheal  Intubation  Outside  the  Operating  Room 


ben/oate  (Hunicaine)  to  the  oral  cavity  and  oropharynx. 
Suction  out  excess  anesthetic.  Remove  the  patient's  oxy- 
gen mask  only  brieCly  during  this  procedure.  Remember 
that  the  patient  probably  cannot  tolerate  low  oxygen  ten- 
sions for  more  than  a  few  seconds  at  a  time.  This  maneu- 
ver may  be  repeated  2-3  times,  waiting  30-60  seconds 
between  each  application  of  topical  anesthetic  and,  of 
course,  oxygenating  and  reassuring  the  patient.  The  degree 
of  anesthesia  can  be  tested  with  a  tongue  depressor  or  the 
laryngoscope  blade.  After  initial  topicalization.  gently  in- 
sert the  laryngoscope  blade  into  the  patient's  mouth  and 
continue  to  perform  the  same  sequence  of  topicalization 
followed  by  mask  oxygenation.  The  goal  here  is  to  sup- 
press the  gag  reflex,  to  insert  the  blade  more  and  more 
deeply,  and  to  ultimately  visualize  and  anesthetize  the  epi- 
glottis and  the  larynx.  The  trachea  can  be  intubated  once 
the  larynx  is  visualized.  Formal  local  anesthesia  of  the 
airway,  including  superior  laryngeal  and  recurrent  laryn- 
geal nerve  blocks,'  is  not  usually  recommended,  because 
the  patient  should  retain  a  cough  reflex  in  the  setting  of  a 
full  stomach. 

Intravenous  Sedation 

Administration  of  intravenous  sedation  to  a  patient  in 
respiratory  distress  is  an  exercise  in  competing  risks  and 
benefits.  To  maintain  airway  protection,  it  is  generally 
desirable  to  have  the  patient  remain  awake.  In  addition, 
too  much  sedation  may  make  the  patient  less  cooperative 
or  render  the  patient  apneic.  Therefore,  intravenous  seda- 
tion should  be  administered  by  gradual  titration,  with  the 
ultimate  goal  of  permitting  an  awake  intubation.  General 
anesthesia  is  rarely  necessary,  and  a  full  discussion  of 
anesthetic  techniques  is  beyond  the  scope  of  this  review.  A 
reasonable  strategy  for  intravenous  sedation  is  to  begin 
with  small  amounts  of  a  benzodiazepine,  such  as  1  mg  of 
diazepam  or  0.5  mg  of  midazolam,  with  adequate  time 
between  doses  to  assess  the  effects.  Other  drugs  that  may 
be  useful  include  fenlanyl  and  morphine.  These  are  potent 
respiratory  depressants  and  must  be  carefully  titrated  in 
patients  with  respiratory  distress.  Titrate  the  drugs  and 
perform  successive  laryngoscopies  in  the  same  way  as 
described  above  for  the  topical  anesthetic  sequence.  In  the 
vast  majority  of  cases,  it  will  be  possible  to  perform  en- 
dotracheal intubation  with  a  combination  of  topical  anes- 
thesia and  moderate  intravenous  sedation.  A  common  pit- 
fall of  the  inexperienced  is  that  impatience  in  waiting  for 
the  full  sedative  effects  of  the  drug  results  in  an  overdose 
to  the  patient.  Apnea  is  not  beneficial  for  patients  in  re- 
spiratory distress! 

Anesthesia  and  Neuromuscular  Blockade 

Rarely,  despite  the  above  techniques,  lack  of  patient 
cooperation  prevents  endotracheal  intubation.  In  such  cases, 


deep  sedation  followed  by  the  administration  of  a  neuro- 
muscular blocking  agent  can  be  considered.  In  general, 
muscular  paralysis  should  only  be  performed  when  you 
are  reasonably  certain  that  intubation  or  mask  ventilation 
is  possible.  Reasonable  certainty  can  be  established  by 
knowledge  of  the  prior  airway  management  history  of  the 
patient,  establishment  of  a  mask  airway  and  positive  pres- 
sure ventilation  (PPV)  after  intravenous  sedation,  or  visu- 
alization of  the  epiglottis  and/or  posterior  arytenoids  dur- 
ing preliminary  attempts  at  laryngoscopy.  Such 
reassurances  are  not  a  guarantee  of  success.  Remember 
that  the  administration  of  a  paralytic  agent  converts  a  spon- 
taneously breathing  patient  with  a  marginal  airway  into  an 
apneic  patient  with  no  airway. '"^  Severe  hypoxemia  will 
occur  before  the  effects  of  a  customary  I  mg/kg  dose  of 
succinylcholine  dissipate.-"  Provisions  to  rapidly  gain  sur- 
gical access  to  the  airway  via  cricothyrotomy  or  tracheos- 
tomy must  be  present  if  neuromuscular  blockade  is  to  be 
attempted  under  emergency  conditions. 

Despite  the  potential  dangers  outlined  above,  the  u.se  of 
neuromuscular  blocking  agents  to  facilitate  emergency  en- 
dotracheal intubation  by  emergency  medicine  physi- 
cians'' -'  and  by  paramedics  in  the  field--*-''  has  greatly 
increased  in  popularity  in  recent  years.  The  administration 
of  neuromuscular  blocking  agents  to  facilitate  endotra- 
cheal intubation  has  become  firmly  established  in  emer- 
gency medicine.  Neuromuscular  blocking  agents  are  used 
routinely  during  endotracheal  intubations  in  95%  of  resi- 
dency-affiliated emergency  departments.-"  In  a  one-year 
study  of  610  endotracheal  intubations  performed  in  the 
Emergency  Department  at  the  University  of  California, 
Davis,  Medical  Center,  84%  of  patients  received  a  rapid- 
sequence  intubation  with  the  use  of  paralytic  drugs.^'' 
Approximately  1  %  of  patients,  however,  could  not  be  suc- 
cessfully intubated  and  required  emergency  cricothy- 
rotomy. Esophageal  intubations  occurred  in  5%  of  pa- 
tients. 

The  administration  of  neuromuscular  blocking  agents 
during  endotracheal  intubation  by  paramedics  in  the  field 
remains  controversial.  Retrospective  reports  suggest  that 
the  u.se  of  neuromuscular  blocking  agents  can  increase  the 
rate  of  successful  intubation  in  the  field,  but  the  ratio  of 
successful  intubations  to  total  attempts  remains  low  (ap- 
proximately 2:3)  and  the  overall  eventual  success  rate  for 
intubation  is  approximately  90-95%.-^  While  this  rate  ap- 
pears acceptable  on  initial  examination,  a  5-10%  failure 
rate  would  quickly  put  most  hospital  operating  rooms  out 
of  business.  It  remains  unclear  if  there  is  an  "acceptable" 
rate  of  lost  airways  and  emergency  cricothyrotomies  in 
these  settings. 

Succinylcholine  remains  the  paralytic  agent  of  choice 
for  emergency  endotracheal  intubation.  Specific  contrain- 
dications to  the  use  of  succinylcholine  center  on  the  risk  of 
severe  hyperkalemia  and  cardiac  arrest  in  susceptible  pa- 


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Orotracheal  Intubation  Outside  the  Operating  Room 


tients.  Such  patients  include  those  with  bums  or  crush 
injuries  (although  succinylcholine  appears  safe  in  the  acute 
setting),  those  who  have  been  immobilized  or  at  prolonged 
bedrest  (including  most  patients  in  intensive  care  units), 
and  those  with  preexisting  hyperkalemia.  A  history  of  ma- 
lignant hyperthermia  is  also  an  absolute  contraindication 
to  the  use  of  succinylcholin6. 

Nondepolarizing  neuromuscular  blocking  agents  are 
slow  in  onset,  and  for  that  reason  are  quite  dangerous  for 
the  patient  who  cannot  tolerate  even  a  few  seconds  of 
depressed  ventilation.  As  stated  above,  all  such  patients 
should  be  considered  to  have  full  stomachs.  Thus,  when 
paralysis  is  chosen,  the  intubation  becomes  "rapid  se- 
quence": administer  the  neuromuscular  blocking  agent  im- 
mediately after  rendering  the  patient  rapidly  unconscious 
with  a  drug  such  as  propofol,  etomidate,  or  ketamine.  Ap- 
ply cricoid  pressure  (the  Sellick  maneuver)  with  the  onset 
of  unconsciousness.  To  minimize  gastric  insufflation  and 
the  risk  of  regurgitation,  under  ideal  circumstances,  avoid 
PPV  until  the  airway  is  secured  by  an  endotracheal  tube.  If 
the  intubation  is  not  immediately  successful,  PPV  may  be 
administered  via  bag  and  mask  with  maintenance  of  cri- 
coid pressure  or  via  laryngeal  mask  airway. 

Alternative  Intubation  Techniques 

Fiberoptic  Intubation 

The  flexible  fiberoptic  laryngoscope  consists  of  glass 
fibers  that  are  bound  together  to  provide  a  flexible  unit 
(the  insertion  tube)  for  the  transmission  of  light  and  im- 
ages. The  flexible  fiberoptic  laryngoscope  can  be  used  in 
both  awake  and  anesthetized  patients  to  evaluate  and  in- 
tubate the  airway.-**  It  can  be  used  for  both  nasal  and  oral 
endotracheal  intubation  and  should  be  considered  as  a  first 
option  in  an  anticipated  difficult  airway,  rather  than  as  a 
"last  resort."  Fiberoptic  intubation  should  be  considered 
for  patients  with  known  or  suspected  cervical  spine  pa- 
thology, head  and  neck  tumors,  morbid  obesity,  or  a  his- 
tory of  difficult  ventilation  or  intubation. 

Standard  equipment  for  oral  or  nasal  fiberoptic  intuba- 
tion includes  a  sterile  fiberoptic  scope  with  light  source,  an 
oral  bite  block  or  Ovassapian  airway,  topical  anesthetics 
and  vasoconstrictors,  and  suction. 

To  perform  a  fiberoptic  intubation,  place  an  endotra- 
cheal tube  over  a  lubricated  fiberoptic  scope,  attach  suc- 
tion tubing  to  the  suction  port,  and  grasp  the  control  lever 
with  one  hand  and  use  the  other  hand  to  advance  and 
maneuver  the  insertion  tube.  An  oral  Ovassapian  airway  is 
helpful  and  well  tolerated  for  oral  laryngoscopy.  After  the 
administration  of  topical  or  general  anesthesia,  flex  the  tip 
of  the  insertion  tube  scope  anteriorly  and  position  it  within 
the  hypopharynx.  Advance  the  scope  toward  the  epiglottis. 
To  avoid  entering  the  pyriform  fossa,  keep  the  insertion 


tube  of  the  fiberoptic  scope  in  the  midline  as  it  is  ad- 
vanced. If  the  view  becomes  impaired,  retract  the  scope 
until  the  view  clears,  or  remove  it  and  clean  the  lens,  and 
then  reinsert  it  in  the  midline.  As  the  tip  of  the  scope  slides 
beneath  the  epiglottis,  the  vocal  cords  will  be  seen.  Ad- 
vance the  scope  with  the  tip  in  a  neutral  position  until 
tracheal  rings  are  ob.served.  Then  stabilize  the  scope  and 
advance  the  endotracheal  tube  over  the  insertion  tube  and 
into  the  trachea.  Sometimes  the  tip  of  the  endotracheal 
tube  becomes  caught  against  the  arytenoids  during  ad- 
vancement. If  there  is  resistance,  turning  the  endotracheal 
tube  90  degrees  counterclockwise  will  allow  passage 
through  the  vocal  cords. -"^ 

Light  Wand 

The  light  wand  consists  of  a  malleable  lighted  stylet 
over  which  an  oral  endotracheal  tube  can  be  passed  blindly 
into  the  trachea.^"  The  endotracheal  tube  is  first  placed  on 
the  stylet  in  the  conventional  fashion,  taking  care  that  the 
stylet  does  not  protrude  through  the  Murphy  eye  or  the  tip 
of  the  endotracheal  tube.  To  insert,  dim  the  operating  room 
lights,  and  advance  the  light  wand  and  endotracheal  tube 
following  the  curve  of  the  tongue.  A  glow  noted  in  the 
lateral  neck  indicates  that  the  tip  of  the  endotracheal  tube 
lies  in  the  pyriform  fossa.  If  the  tip  enters  the  esophagus, 
there  is  a  marked  decrease  in  the  light's  brightness.  When 
the  tip  is  correctly  positioned  in  the  trachea,  a  marked 
glow  is  noted  in  the  anterior  neck.  At  this  point,  slide  the 
endotracheal  tube  off  the  light  wand  in  the  same  manner  as 
with  a  standard  malleable  stylet. 

Digital  Intubation 

Orotracheal  intubation  without  the  use  of  a  laryngo- 
scope has  been  well  described  but  offers  few  advantages 
over  more  traditional  approaches,  except  as  a  technique  of 
last  resort  or  when  traditional  equipment  is  unavail- 
able.'''-^'-'- To  perform  an  oral  intubation  without  the  ben- 
efit of  a  laryngoscope,  position  the  patient  in  the  standard 
manner  and  stand  facing  the  patient.  Insert  the  index  and 
middle  fingers  of  your  left  hand  into  the  right  side  of  the 
patient's  mouth.  Press  down  on  the  tongue  while  sliding 
your  tlngers  along  the  midline  until  you  feel  the  epiglottis. 
Pull  the  epiglottis  forward  with  your  middle  finger.  Insert 
the  endotracheal  tube  using  your  right  hand  and  advance 
the  tube  along  the  lateral  aspect  of  your  left  index  finger, 
guiding  its  tip  toward  the  glottis.  Once  the  cuff  of  the  tube 
passes  approximately  2  inches  beyond  the  tip  of  your  in- 
dex finger,  stabilize  the  tube  and  remove  your  left  hand. 
Check  for  proper  tube  placement  in  the  usual  manner  (see 
below). 


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623 


Orotracheal  Intubation  Outside  the  Operating  Room 


End-Tidal 

PCO2 
(mmHg) 


71 


35 


n  nrio 


ISI 


2nd 


3rd 


Breaths 


4th 


5th 


6lh 


Fig.  1 1 .  Partial  pressure  of  carbon  dioxide  (Pcos)  waveforms  from  an  esophageal  intubation.  Note  that  the  waveform  may  be  misleading, 
but  that  the  end-tidal  value  should  decrease  progressively  with  ventilation.  (From  Reference  43,  with  permission.) 


Verification  of  Intubation 

Verification  of  proper  endotracheal  tube  position  within 
the  trachea  and  immediate  recognition  of  an  esophageal 
intubation  remain  problematic.  Esophageal  intubation  is 
one  of  the  most  common  mistakes  in  airway  management 
associated  with  a  fatal  outcome.'^  Regrettably,  no  verifi- 
cation technique  is  entirely  foolproof."  The  usual  standard 
of  care  for  verification  of  proper  endotracheal  tube  posi- 
tion includes  the  persistent  detection  of  COt  in  end-tidal 
samples  of  exhaled  gas,  and  auscultation  over  the  stomach 
and  both  lung  fields.  Listening  for  breath  sounds  high  in 
each  axilla  may  decrease  the  chances  of  being  misled  by 
transmitted  breath  sounds  from  the  opposite  lung.  If  breath 
sounds  are  heard  over  only  one  side  of  the  thorax,  a  main 
stem  intubation  should  be  suspected,  and  the  endotracheal 
tube  should  be  withdrawn  until  breath  sounds  are  heard 
bilaterally.  If  breath  sounds  are  not  heard  over  the  thorax, 
or  are  heard  over  the  epigastrium,  suspect  an  esophageal 
intubation  and  remove  the  tube. 

End-Tidal  Carbon  Dioxide 

The  measurement  of  the  CO^  concentration  in  exhaled 
gas  has  become  a  standard  for  verifying  tracheal  place- 
ment of  a  breathing  tube.  In  the  absence  of  a  capnometer, 
disposable  colorimetric  CO2  detectors  can  be  used  to  con- 
firm the  presence  of  COt.^''  "  Surprisingly,  this  technique 
is  not  foolproof  COt  will  not  be  present  if  pulmonary 
circulation  is  absent  (eg,  in  a  dead  patient  or  in  the  absence 
of  adequate  chest  compressions  during  cardiopulmonary 
circulation).^'*--*" 

Small  concentrations  of  COj  may  be  detected  after  an 
esophageal  intubation,  especially  if  bag  and  mask  ventila- 
tion has  insufflated  previously  exhaled  air  into  the  stom- 
ach (Fig.  1 1).^'  Linko  et  al  reported  that  a  CO^  waveform 
was  obtained  in  4.'i<7r  of  esophageal  intubations.-*-  The  end- 
tidal  concentration  ranged  from  0.2-1.5%.  Sum-Ping  et  al 


reported  a  CO,  concentration  of  up  to  2%  following  esoph- 
ageal intubation.  In  this  study,  CO2  waveforms  were  de- 
tected in  33%  of  esophageal  intubations.-*'  In  an  esopha- 
geal intubation,  the  yellow  color  of  the  CO,  detector  usually 
becomes  progressively  weaker  with  repetitive  breaths  as 
the  CO2  is  washed  out.  With  an  endotracheal  intubation, 
the  yellow  color  should  persist  over  repeated  exhalations. 
If  the  yellow  color  does  not  persist,  additional  confirma- 
tion is  necessary. 

Physical  Signs  and  Symptoms 

One  sign  of  a  successful  intubation  is  for  the  operator  to 
watch  the  tube  go  through  the  vocal  cords.  Other  methods 
for  verifying  the  placement  of  the  endotracheal  tube  in- 
clude observation  of  chest  and  abdominal  movement,  aus- 
cultation of  breath  sounds  over  both  the  right  and  left  chest 
and  abdomen,  palpation  of  the  abdomen,  and  palpation  of 
the  trachea  as  the  tube  is  passed.-*'*-*  As  a  routine  measure, 
auscultate  over  the  epigastrium  and  observe  the  chest  for 
thoracic  inflation  with  the  first  positive  pressure  breath.'" 
Gurgling  sounds  over  the  stomach  and  the  absence  of  no- 
ticeable chest  wall  expansions  are  signs  of  esophageal  in- 
tubation, in  which  case  ventilation  through  the  tube  should 
be  discontinued  immediately  and  the  tube  removed.  The 
exhaled  tidal  volume  can  also  be  measured,  and  is  reduced 
with  an  esophageal  intubation.*'  Water  vapor  may  be  ob- 
served to  fill  the  endotracheal  tube  upon  expiration  and 
disappear  upon  inspiration  after  proper  placement.  Other 
techniques  for  confirming  endotracheal  tube  placement  in- 
clude fiberoptic  endoscopy,-*""  the  use  of  a  self-inflating 
bulb  (the  esophageal  detector),*''"*'*  an  air  flow  whistle*'* 
on  the  proximal  end  of  the  endotracheal  tube,  and  chest 
radiography.^" 

While  any  or  all  of  these  tests  can  be  performed,  re- 
member that  no  single  test  is  adequate  to  reliably  exclude 
an  esophageal  intubation.  In  the  absence  of  direct  visual- 
ization of  the  endotracheal  tube  passing  between  the  vocal 


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Orotracheal  Intubation  Outside  the  Operating  Room 


cords,  a  very  high  index  of  suspicion  of  incorrect  tube 
placement  must  be  maintained  for  the  first  several  minutes 
following  intubation.  Remain  in  the  room  and  continue  to 
observe  the  chest  movement  and  the  results  of  PPV.  Only 
after  adequate  oxygenation  and  two-lung  ventilation  ap- 
pears certain  (ie,  after  several  minutes),  is  it  safe  to  leave 
the  patient  under  the  care  of  others. 

Complications  of  Intubation 

Complications  of  orotracheal  intubation  include  injury 
of  the  lips,  tongue,  teeth,  pharynx,  or  tracheal  mucosa. 
There  can  be  (though  rarely)  avulsion  of  arytenoid  carti- 
lages or  damage  to  vocal  cords.  Lacerations  of  the  trachea 
have  been  reported.'''  Hypertension,  tachycardia,  and  dys- 
rhythmias can  occur  as  a  result  of  laryngoscopy.  Hypo- 
tension is  common  with  the  use  of  sedative  drugs  and  the 
onset  of  PPV.  Aspiration  of  regurgitated  gastric  contents 
and  blood,  esophageal  intubation,  and  endobronchial  intu- 
bation can  also  occur.  Excessive  endotracheal  cuff  pres- 
sures can  produce  ischemia  of  the  tracheal  mucosa  and 
subsequent  tracheal  stenosis. '"■-'*- 

Immediate  Care  of  the  Patient  after  Intubation 

Radiographic  confirmation  of  endotracheal  tube  posi- 
tion is  always  prudent  following  an  emergency  intubation. 
Plans  for  further  sedation  and,  if  necessary  muscular  pa- 
ralysis, should  be  constructed.  If,  for  example,  succinyl- 
choline  has  been  required  to  facilitate  intubation,  there  is 
a  good  chance  that  the  patient  will  be  difficult  to  control  as 
soon  as  the  drug's  effect  wears  off.  In  the  early  period 
following  semi-emergency  intubation,  it  will  often  be  ap- 
propriate to  institute  neuromuscular  blockade  with  a  non- 
depolarizing muscle  relaxant,  especially  if  the  patient  is  to 
be  transported  to  another  part  of  the  hospital.  Pancuro- 
nium, vecuronium,  and  cisatracurium  are  usual  choices. 
Adequate  and  continuing  intravenous  sedation  is  manda- 
tory if  neuromuscular  blockade  is  to  be  continued,  because 
pharmacologic  paralysis  while  awake  is  terrifying  to  the 
patient.  Continue  to  monitor  the  patient's  vital  signs  with 
regard  to  the  patient's  underlying  cardiovascular  function 
(as  well  as  that  of  other  organ  systems)  and  treat  the  pa- 
tient appropriately  and  expeditiously.  Continuously  assess 
oxygenation  and  ventilation,  and  choose  settings  for  me- 
chanical ventilation  based  on  the  initial  assessment  and 
response  to  therapy. 

ACKNOWLEDGEMENTS 

The  author  acknowledges  with  thanks  the  contributions  of  Dr  James  T 
Roberts  in  his  teaching  of  endotracheal  intubation  techniques,  the  anat- 
oiTiy  lessons  of  Dr  Richard  Pino,  and  the  practical  contributions  of  the 
anesthesiology  residents  of  the  Massachusetts  General  Hospital.  Many  of 
the  recommendations  in  this  chapter  were  derived  from  discussions  on 


emergency  airway  management  that  took  place  in  1994-.').  and  which 
involved  representatives  from  the  anesthesia  departments  of  the  Massa- 
chusetts General  Hospital,  the  Brigham  and  Women's  Hospital.  Boston's 
Beth  Israel  Hospital,  the  New  England  Deaconess  Hospital,  and  Boston 
Children's  Hospital. 

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in  the  morbidly  obese.  Anesthesiology  1996;85(2):246-253. 
Cook  RT  Jr,  Moglia  BB,  Consevage  MW,  Lucking  SE.  The  use  of 
the  Beck  Airway  Airflow  Monitor  for  verifying  intratracheal  endo- 
tracheal tube  placement  in  patients  in  the  pediatric  emergency  de- 
partment and  intensive  care  unit.  Pediatr  Emerg  Care  1 996;  12(5): 
331-332. 

50.  Smith  GM,  Reed  JC,  Choplin  RH.  Radiographic  detection  of  esoph- 
ageal malpositioning  of  endotracheal  tubes.  AJR  Am  J  Roentgenol 
1990;154(l):23-26. 

5 1 .  Marty-Ane  CH,  Picard  E,  Jonquet  O,  Mary  H.  Membranous  tracheal 
rupture  after  endotracheal  intubation.  Ann  Thorac  Surg  1995:60(5): 
1367-1371. 

Blanc  VF,  Tremblay  NA.  The  complications  of  tracheal  intubation: 
a  new  classification  with  a  review  of  the  literature.  Anesth  Analg 
1974;53(2):202-213. 


38. 


39, 


40, 


41 

42 


43 


44 


45 


46, 


47 


48 


49, 


52 


Discussion 

Bishop:  First,  a  comment  on  the 
esophageal  detector  device.  A  recent 
paper  by  Carol  Kasper  and  Steve 
Deem,  from  the  Harborview  Respira- 
tory Therapy  Department,  looks  pro- 
spectively at  the  u.se  of  the  self-inflat- 
ing bulb  syringe  for  determination  of 
intubation.'  It  shows  basically  what's 
been  shown  in  some  nonemergency 
situations  before,  which  is  that  if  the 


tube  is  in  the  esophagus,  you'll  al- 
ways get  a  negative  response  from  the 
bulb  syringe.  In  other  words,  you're 
not  going  to  intubate  the  esophagus 
and  think  that  you're  in  the  trachea. 
However,  occasionally  in  obese  pa- 
tients, in  patients  with  secretions,  or 
in  patients  with  bronchospasm,  the 
tube  may  be  in  the  trachea,  but  the 
bulb  will  not  reinflate.  In  our  hospital, 
the  esophageal  detector  device  is  used 
because  the  colorimetric  detectors  cost 


$17  or  $18,  and  may  not  be  useful  in 
arrest  situations.  The  bulb  syringes  we 
put  together  for  80  cents  each,  and 
that's  what's  on  our  intubation  trays. 
Again,  we  run  into  problems  with  pa- 
tients with  copious  secretions.  We 
think  it  really  works  pretty  well,  prob- 
ably better  than  the  colorimetric  de- 
vice. And  for  paramedics  in  the  field 
where  there's  often  not  much  light, 
it's  hard  to  tell  a  colorimetric  change 
if  the  patient's  arrested. 


626 


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Orotracheal  Intubation  Outside  the  Operating  Room 


REFERENCE 

1 .  Kasper  CL.  Deem  S.  The  self-inflating  bulb 
to  detect  esophageal  intubation  during 
emergency  airway  management.  Anesthe- 
siology 1998;88(4):898-902. 

Thompson:  We  use  the  end-tidal  de- 
tector routinely.  We  make  a  concerted 
effort  to  teach  people  about  its  limits 
in  the  setting  of  absent  pulmonary 
blood  flow,  but  feel  that  its  benefits  in 
other  settings  markedly  outweigh  the 
potential  for  misunderstanding  it  dur- 
ing resuscitation.  In  a  study  we  per- 
formed in  piglets,  we  found  that,  at 
least  in  a  small  animal,  even  when  the 
stomach  is  filled  with  a  carbonated 
beverage,  there  were  no  false  posi- 
tives.' I'm  not  aware  of  a  single  ex- 
ception to  this  understanding  in  an  in- 
fant or  child.  We  were  aware  of  the 
earlier  studies  and  decided  to  look  at 
the  issue  specifically.  We  just  didn't 
see  any  evidence  of  carbonated  stom- 
ach contents  causing  false  readings. 
My  conclusion  is  that  the  risk  entailed 
in  the  use  of  the  end-tidal  detector  is 
of  a  false  negative — not  recognizing 
correct  tube  placement  in  the  airway 
because  of  the  absence  of  COt  in  ex- 
haled gases  during  cardiopulmonary 
arrest  or  very,  very  low  pulmonary 
blood  flow.  I  think  the  risk  of  a  false 
positive  is  vanishingly  low. 

REFERENCE 

I.  Bhende  MS.  Thompson  AE.  Howland 
DF.  Validity  ofa  disposable  end-tidal  car- 
bon dioxide  detector  in  verifying  endo- 
tracheal tube  position  in  piglets.  Crit  Care 
Med  l99I:19(4):566-568. 

Reibel:  You've  hit  on  a  good  point, 
I  think,  that  we  need  to  talk  to  the 
folks  in  emergency  and  internal  med- 
icine about  integrating  training  for 
their  residents — how  to  actually  bag 
and  mask  somebody — and  that  that, 
for  most  of  these  patients,  is  all  they 
need.  They  don't  need  someone  with 
minimal  experience  fooling  around  in 
the  airway  with  a  laryngoscope  that 
may  or  may  not  work,  with  poor  or  no 
suction  equipment,  and  insufficient 


support  personnel.  Also  the  idea  of  an 
emergency  nasotracheal  intubation  is 
an  oxymoron. 

Durbin:  I  wanted  to  get  my  pitch  in 
early.  I  probably  don't  want  to  talk 
extensively  about  this  until  we  present 
some  of  the  issues  about  who  should 
perform  intubations.  I  do  want  to  get 
this  issue  onto  the  agenda  for  discus- 
sion: What  should  the  role  of  the  re- 
spiratory therapist-intubator  be  in  ad- 
ministration of  drugs?  This  includes 
the  whole  issue  of  conscious  sedation, 
which  is  important  in  urgent  but  not 
emergency  intubations.  You  men- 
tioned the  issue  at  the  end  of  your 
comments  when  you  said  "Well,  we 
don't  need  to  worry  about  that;  get  an 
anesthesiologist."  I  think  there  are  in- 
stitutions that  don't  have  anesthesiol- 
ogists 24  hours  a  day.  There  are  going 
to  be  patients  who  need  to  be  intu- 
bated by  individuals  other  than  phy- 
sicians. What  should  the  role  of  non- 
physicians  (and  non-nurses)  be  in  the 
administration  ofdrugs?  These  include 
sedative  drugs,  local  anesthetics,  and 
nerve  blocks.  In  what  situations  should 
respiratory  therapists  be  allowed  to  do 
it?  Should  they  be  licensed  to  do  it? 
And  are  they  capable?  The  American 
Association  for  Respiratory  Care  has 
made  a  position  statement  saying  that 
respiratory  therapists,  if  properly 
trained,  taught,  and  demonstrated  com- 
petent, should  be  capable  of  providing 
conscious  sedations.'  Should  respira- 
tory therapists  who  have  a  role  in  emer- 
gency airway  management  be  able  to 
use  these  drugs  for  that  purpose? 

REFERENCE 

1 .  Administration  of  .sedative  and  analgesic 
medications  by  respiratory  care  practitio- 
ners: a  position  statement  from  the  Amer- 
ican Association  for  Respiratory  Care.  Re- 
spirCare  1998;43(8):6.'i.'). 

Bishop:  I'm  going  to  take  issue  with 
your  condemnation  of  the  use  of  neu- 
romuscular blockers.  I  would  say  that 
in  the  patient  who  has  desaturated, 
they're  biting  down.  I  think  you  can 


secure  the  airway  more  quickly  and 
reliably  with  the  use  of  a  neuromus- 
cular blocker.  In  fact,  in  our  situation 
where  we've  been  training  respiratory 
therapists,  one  of  the  things  we've  been 
pushing  for  is  the  recognition  that  neu- 
romuscular blockade  in  some  cases 
may  be  the  safest  thing  to  do  in  terms 
of  rapidly  securing  the  airway. 

Hurford:  I'll  agree  that  there  are 
many  intubations  where  the  use  of  a 
neuromuscular  blocker  is  the  safest 
and  most  expeditious  route,  and  I  don't 
mean  to  condemn  the  use  of  neuro- 
muscular blockers  uniformly.  What  I 
think  that  I  do  disagree  with,  though, 
is  the  routine  protocol  use  of  rapid 
sequence  intubation  as  the  intubation 
technique  of  choice  for  all  patients  en- 
tering an  emergency  room.  I  think  that 
taking  away  the  ability  to  ventilate  and 
maintain  airway  for  all  patients  in  re- 
spiratory distress  who  require  endo- 
tracheal intubation  is  unnecessarily 
dangerous.  You  saw  by  those  surveys, 
in  some  emergency  departments  about 
85%  of  patients  are  now  just  simply 
receiving  rapid  sequence  intubations. 
I  put  patients  with  airway  obstruction 
or  partial  airway  obstruction  into  that 
group.  I  think  that's  going  to  result  in 
a  noticeable  proportion  of  patients  who 
require  surgical  airways  who  may  not 
have  otherwise.  If  we  are  going  to  take 
that  approach,  we  need  to  decide  what 
is  an  acceptable  rate  of  airway  loss, 
and  when  that  loss  occurs,  what  we 
are  going  to  do  about  it.  An  anesthe- 
siologist on  the  phone  is  not  going  to 
be  helpful  when  the  succinylcholine 
has  been  given  and  the  patient  cannot 
be  ventilated  or  intubated.  So  we  have 
to  have  some  way  out,  whether  that's 
a  laryngeal  mask,  some  other  adjunct, 
or  the  ability  to  immediately  surgi- 
cally access  the  airway  by  a  surgeon 
who  is  trained  and  knows  what  he's 
doing — not  by  an  individual  who's 
been  trained  only  by  doing  it  once  on 
a  sheep. 

Bishop:  We're  in  agreement  that 
judgment  should  play  a  role,  and  that 


Respiratory  Care  •  June  1999  Vol  44  No  6 


627 


Orotracheal  Intubation  Outside  the  Operating  Room 


we  need  to  spend  some  time  teaching 
people  judgment,  but  I  think  you're 
speaking  from  a  position  of  having 
the  luxury  of  having  anesthesiologists 
and  surgeons.  That  isn't  the  reality  in 
some  hospitals.  We  concluded  it  would 
cost  our  hospital  $  1 50,000-$200,000 
a  year  to  have  someone  in-house  who 
was  either  a  highly  trained  emergency 
room  physician  or  a  nurse  anesthetist 
or  anesthesiologist  to  cover  24  hours 
a  day. 

Hurford:  Right.  That  luxury  has  a 
cost  that  you  have  defined  as  far  as 
personnel  and  time.  It  will  also  have  a 
cost  in  complication  rates.  Certainly 
those  things  can  be  traded  off.  They're 
traded  off  by  air  ambulance  services 
all  the  time  with  their  use  of  neuro- 
muscular blockades.  This  trade-off  is 
one  that  needs  to  be  better  defined. 
The  role  of  failure  also  needs  to  be 
better  defined. 

Reibel:  If  the  hospital  is  not  one 
that  has  people  available  to  reintubate 
the  patient,  the  patient  needs  a  surgi- 
cal airway  or  transfer  to  a  hospital  that 
provides  the  level  of  care  they  need. 

Heffner:  Just  a  brief  comment  about 
paralytic  agents.  In  the  last  8  years,  I 
was  in  an  institution  where  we  did 
have  24-hour  trauma  anesthesiologists 
and  24-hour  obstetric  anesthesiolo- 
gists, which  was  a  wonderful  value 
when  house  staff  were  making  the  first 
attempt  to  intubate,  soon  to  have  the 
shadow  of  an  anesthesiologist,  a  more 
experienced  person  over  their  shoul- 
der in  the  next  few  minutes.  We  did 
have  one  trauma  anesthesiologist  who 
was  wedded  to  the  idea  of  big  induc- 
tion doses  of  vecuronium,  routinely, 
for  every  intubation.  Our  major  prob- 
lem with  that  approach  was  that  we 
were  left  with  a  patient  who  was  par- 
alyzed for  hours.  The  residents  had  a 
greater  challenge  adjusting  the  venti- 
lator once  the  anesthesiologist  left  the 
intensive  care  unit.  And  we  had  a  lot 
more  use  of  blood  gases  and  a  lot  more 
hypoventilating  patients  over  the  sub- 


sequent hours  compared  with  patients 
intubated  by  other  anesthesiologists 
who  were  not  using  paralytic  agents 
routinely.  They  reserved  paralytics  for 
difficult  intubations.  We  also  had  a 
number  of  patients  wake  up  and  re- 
member the  experience.  Lastly,  we  had 
a  few  patients,  even  with  the  skilled 
hands  of  an  anesthesiologist,  who 
couldn't  be  intubated  with  paralytics. 
This  converted  an  urgent  intubation 
into  a  disaster. 

Durbin:  My  bias  is  that  relaxants 
should  be  the  last  choice,  for  the  rea- 
sons that  have  been  stated.  However, 
in  inexperienced  hands,  the  chance  of 
success  of  intubation  is  higher  with  a 
relaxant.  It's  a  double-edged  sword. 
Bill,  you've  been  saying  we  need  to 
know  when  we'  re  hurting  people  when 
we  do  this,  because  we  can  understand 
that  when  we  can't  get  that  airway, 
that's  a  bad  outcome.  But  I'd  also  say 
that  if  there  aren't  more  experienced 
people  around,  the  bad  outcome  is  not 
having  an  airway  in  the  first  place.  So 
I  don't  know  what  the  denominator 
is — how  many  patients  are  harmed  by 
relaxants  versus  helped  by  relaxants. 
And  I  don't  know  that  there's  any- 
thing in  the  literature  that  answers  that 
question.  We  were  talking  about  da- 
tabases and  information.  This  is  some- 
thing on  which  data  have  not  been 
accumulated,  to  my  knowledge.  1  be- 
lieve that  relaxants  in  inexperienced 
hands  are  a  bad  thing,  but  1  really  don't 
have  the  data  to  support  that  this  is,  in 
fact,  true. 

Hurford:  lagree  that  the  data  aren't 
out  there,  because  when  bad  things  do 
happen  they  tend  to  not  go  in  the  same 
database  as  when  things  go  well.  They 
tend  not  to  end  up  published  in  the 
journals  as  case  series.  Certainly,  1 
agree  with  your  experiences,  Dr  Hef- 
fner, and  they  echo  our  own  in  that 
you  do  end  up  with  a  definable  pop- 
ulation. I  think  that's  a  reasonable 
number  of  patients,  but  I  agree,  I  don't 
know  how  many  that  is,  and  I  don't 
know  how  many  is  reasonable.  1  also 


see  the  other  side  of  the  coin:  For  any- 
body, no  matter  how  experienced, 
there  is  a  point  where  you  say,  "This 
patient  will  die  unless  I  do  something 
about  it,  unless  I  give  them  that  one 
last  try  or  the  one  last  dose  of  succi- 
nylcholine."  So  you  go  ahead  and  do 
it.  I'm  not  saying  it  should  not  be  part 
of  an  algorithm.  I  think  it  should  be 
part  of  an  algorithm  further  down  for 
those  who  do  not  have  a  high  level  of 
experience,  and  even  for  those  who 
do  have  a  high  level  of  experience  in 
intubating  outside  of  the  emergency 
room.  It  is  my  third  choice,  still,  after 
the  level  of  experience  that  I've  gained. 

Thompson:  I  certainly  agree  with 
the  issues  about  skill  and  judgment 
always  playing  a  role  here.  However, 
I  have  a  different  point  of  view  on  a 
number  of  these  issues  in  children. 
There's  almost  no  such  thing  as  a  co- 
operative child  during  laryngoscopy, 
and  no  amount  of  sedation  short  of 
general  anesthesia  achieves  that  coop- 
eration. There's  an  occasional  excep- 
tion, but  the  vast  majority  will  require 
not  only  sedation  but  paralysis  if  one 
is  to  minimize  trauma  to  the  airway. 
Our  experience  with  patients  intubated 
in  the  field  without  benefit  of  sedation 
and  neuromuscular  blockade  has  been 
significant  airway  injury  and/or  fail- 
ure to  accomplish  the  intubation.  1 
don't  know  what  the  denominator  is, 
but  I  feel  strongly  that  neuromuscular 
blockade  has  an  important  role,  as- 
suming a  basic  level  of  skill  and 
judgment.  This  is  the  pediatric  inten- 
sivist's  view,  rather  than  the  neona- 
tologist's.  We  are  currently  conduct- 
ing a  randomized  trial  in  neonates 
transported  by  our  transport  team.  I'd 
also  like  to  express  a  strong  bias, 
shared  by  many,  against  the  use  of 
succinylcholine  in  children,  because 
of  an  unacceptably  high  incidence  of 
complications.  With  the  availability  of 
rocuronium  and  its  similar  onset  time, 
there  is  little  advantage  to  administer- 
ing succinylcholine.  The  longer  dura- 
tion of  action  is  commonly  beneficial 


628 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Orotracheal  Intubation  Outside  the  Operating  Room 


in  a  critically  ill  patient  who  is  likely 
to  require  testing,  placing  monitoring 
catheters,  etc,  after  intubation.  The  ar- 
gument that  succinylcholine's  shorter 
duration  of  action  protects  the  patient 
if  intubation  cannot  be  accomplished 
is,  I  believe,  specious. 

Hurford:  I  agree  entirely  with  your 
contraindications  of  succinylcholine  in 
the  young  child  and  the  infant.  My 
talk  is  entirely  aimed  toward  the  adult 
patient.  Everything  else,  I  think,  holds 
fairly  closely  as  far  as  I  can  see,  but 
that  is  one  point  of  departure.  Just  for 
the  sake  of  completeness,  would  you 
describe  your  study  for  us? 

Thompson:  Yes.  A  large  fraction 
of  the  patients  we  transport  every  year 
are  newborns  with  respiratory  prob- 
lems. Many  of  them  require  intuba- 
tion and  ventilation.  We  intend  to  com- 
pare 2  approaches  to  intubation  (each 
of  which  has  vigorous  support  within 
our  institution):  intubation  without  se- 
dation or  paralysis,  and  intubation  us- 
ing a  combination  of  narcotic,  benzo- 


diazepine, and  non-depolarizing 
neuromuscular  blocking  agent. 

Hurford:  I  agree  with  you.  After  the 
airway  has  been  secured,  most  trans- 
port services,  especially  air  services, 
will  paralyze  their  patients  routinely, 
but  routinely  that's  after  the  airway 
has  already  been  secured  and  assured. 
The  controversy,  to  clarify,  is  the  use 
of  relaxants  before  the  airway  is  tested 
or  before  the  airway  is  secured. 

Stoller:  Reflecting  on  this  discus- 
sion about  paralytic  agents,  it  reminds 
me  of  one  of  the  roles,  perhaps,  of  the 
Respiratory  Care  Journal  Confer- 
ences. When  you  assemble  a  group  of 
people  with  tremendous  expertise  who 
are  reviewing  the  literature  exhaus- 
tively, you  may  realize  that  there  is  no 
definitive  study.  One  of  my  axioms  is 
that  the  degree  of  shouting  about  a 
medical  controversy  is  inversely  pro- 
portional to  the  data  upon  which  the 
opinions  are  framed.  It  strikes  me  that 
one  opportunity  in  this  Journal  Con- 
ference is  to  define  a  line  of  inquiry 


that  would  allow  us  to  resolve  this 
question.  Although  randomized  trials, 
as  you  pointed  out,  are  exciting  pos- 
sibilities when  there's  a  specific  hy- 
pothesis, it  seems  to  me  moving  one 
step  proximal  to  generating  a  hypoth- 
esis is  simply  getting  organized  ob- 
servations in  an  unselected  way — in 
other  words,  in  a  consecutive  series 
through  a  spectrum  of  clinical  studies, 
whether  it  be  the  emergency  room,  the 
operating  room,  or  the  hospital  non- 
operating  room  experience.  And 
there's  probably  an  opportunity  for  us 
to  endorse  a  multicenter  registry  of 
consecutive  patients'  airway  manage- 
ment to  frame  these  questions.  So,  one 
concrete  suggestion  that  might  emerge 
from  this  Journal  Conference  is  the 
call  to  various  funding  agencies, 
whether  it  be  the  NIH  [National  Insti- 
tutes of  Health]  or  the  American  Re- 
spiratory Care  Foundation,  to  consider 
a  systematic  inquiry  among  interested 
parties  to  examine  the  true  prevalence. 
Publication  bias  is  a  very  potent  se- 
lection bias. 


Respiratory  Care  •  June  1999  Vol  44  No  6 


629 


Humidification  for  Patients  with  Artificial  Airways 


Richard  D  Branson  RRT 


Introduction 

Normal  Mechanisms  of  Heat  and  Moisture  Exchange 

in  the  Respiratory  Tract 
High-Flow  Humidifiers 

Pass-over  Humidifiers 

Wick  Humidifiers 

Bubble  Humidifiers 
Artificial  Noses 

Moisture  Output 

Resistance 

Dead  Space 

Additives 

Cost 

Choosing  an  Artificial  Nose 
Active  Hygroscopic  Heat  and  Moisture  Exchangers 
HME-Booster 

Use  of  Humidification  Devices  During  Mechanical  Ventilation 
Use  of  Heated  Humidification 

0 

Use  by  Ambulatory  Patients 

[Respir  Care  1999;44(6):630-641]  Key  words:  humidification,  artificial  nose, 
heat  and  moisture  exchanger,  artificial  airway,  humidifiers. 


Introduction 

The  amount  of  water  vapor  in  a  gas  can  be  measured 
and  expressed  in  a  number  of  ways.  In  medicine  the  most 
common  terms  are  absolute  humidity  and  relative  humid- 
ity. Absolute  humidity  is  the  amount  of  water  vapor  present 
in  a  gas  mixture.  Absolute  humidity  is  directly  propor- 
tional to  gas  temperature — increasing  with  increasing  gas 
temperature  and  decreasing  with  decreasing  gas  tempera- 
ture (Table  I).  Absolute  humidity  is  typically  expressed  in 
mg/L,  gmlcvrc',  or  as  a  partial  pressure.  At  the  alveolar 
level,  gas  is  37°  C,  100%  relative  humidity,  and  contains 
43.9  mg  H2O/L. 

A  gas  mixture  is  said  to  be  saturated  or  at  the  maximum 
capacity  of  water  vapor  if  it  contains  the  maximum  pos- 


Richard  D  Branson  RRT  is  affiliated  with  the  Department  of  Surgery  of 
the  University  of  Cincinnati,  Cincinnati.  Ohio. 

Correspondence:  Richard  D  Branson  RRT,  Department  of  Surgery,  Uni- 
versity ol  Cincinnati,  2.?!  Bethesda  Avenue,  Cincinnati  OH  45267-0558. 
E-mail:  richard.branson@uc.edu. 


sible  amount  of  water  vapor  it  is  capable  of  holding  at  that 
temperature.  The  amount  of  humidity  in  a  gas  that  is  less 
than  saturated  can  be  determined  by  comparing  the  abso- 
lute humidity  (the  water  vapor  present)  to  the  maximum 
capacity  (the  maximum  possible  water  vapor)  of  the  gas  at 
a  given  temperature.  This  value  is  known  as  the  relative 
humidity.  Relative  humidity  is  expressed  as  a  percentage 
and  calculated  with  the  following  equation: 

Relative  humidity  (%)  =  (absolute  humidity )/(maximum 
capacity)  X  100. 

The  relative  humidity  of  a  gas  saturated  with  water  va- 
por at  any  temperature  is  100%.  The  temperature  at  which 
a  gas  is  100%  saturated  is  known  as  the  dew  point.  These 
measurements  are  useful  in  determining  the  causes  of  some 
common  clinical  phenomena.  For  example,  if  gas  leaves  a 
heated  humidifier  outlet  at  a  temperature  of  34°  C  and 
100%  relative  humidity  and  is  heated  by  a  heated  wire 
circuit  to  37°  C  at  the  airway,  the  relative  humidity  is 
decreased.  In  this  instance,  if  the  gas  temperature  were  37° 
C  and  the  absolute  humidity  measured  was  37  mg  HjO/L, 
then  we  can  determine  the  relative  humidity  by  comparing 


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HUMIDIFICATION  FOR  PATIENTS  WITH  ARTIHCIAL  AiRWAYS 


Table  1 .      The  Relationship  of  Gas  Temperature,  Absolute  Humidity, 
and  Water  Vapor  Pressure 


Gas 
Temperatue 

(C°) 

Absolute  Humidity 
(mg  H,0/L) 

Water  Vapor 

Pressure 

(Ph,o) 

0 

4.85 

4.6 

5 

6.8 

6.5 

10 

9.4 

9.2 

15 

12.8 

12.8 

20 

17.3 

17.5 

25 

23.0 

23.7 

30 

30.4 

31.7 

32 

33.8 

35.5 

34 

37.6 

39.8 

36 

41.7 

44.4 

37 

43.9 

46.9 

38 

46.2 

49.5 

40 

51.1 

55.1 

42 

56.5 

61.3 

44 

62.5 

68.1 

this  value  to  the  maximum  capacity  for  water  vapor  at  37° 
C  given  in  Table  1:  relative  humidity  (%)  =  37/43.9  X 
100  =  84.3%. 

This  explains  the  occasional  finding  of  dried  secretions 
in  the  endotracheal  tubes  of  patients  using  heated  humid- 
ification  and  heated  wire  circuits.  The  greater  the  differ- 
ence between  temperature  at  the  chamber  and  temperature 
at  the  airway,  the  lower  the  relative  humidity.  This  tem- 
perature offset  is  important  to  keep  the  circuit  free  of 
condensate  or  "rain  out."  Unfortunately,  in  certain  envi- 
ronments (eg,  near  windows,  heating  units,  and  air  condi- 
tioning vents)  environmental  changes  can  affect  heated 
wire  circuit  efficacy.  However,  clinicians  should  be  care- 
ful to  assure  that  the  patient  receives  adequate  relative 
humidity  as  a  priority  over  keeping  the  circuit  free  from 
rain  out.  When  a  heated  humidifier  without  a  heated  wire 
circuit  is  used,  it  is  often  necessary  for  the  gas  in  the 
humidification  chamber  to  reach  50°  C  in  order  for  the 
temperature  delivered  to  the  airway  to  approach  37°  C. 
This  concept  is  illustrated  in  Figure  1 .  In  this  example,  the 
maximum  water  vapor  content  of  gas  at  50°  C  is  83  mg 
HjO/L,  and  the  maximum  water  vapor  content  of  gas  at 
37°  C  is  43.9  mg  HjO/L.  The  difference  in  water  vapor 
content  between  the  2  gases  (83  -  43.9  =  39.1  mg  HjO/L) 
represents  the  amount  of  rain  out  that  will  accumulate  in 
the  circuit.  For  a  minute  ventilation  of  1 0  L/min,  this  would 
result  in  slightly  greater  than  0.5  L  of  rain  out  over  a  24- 
hour  period.' 

If  the  relative  humidity  and  temperature  are  known,  the 
water  vapor  content  can  be  calculated  with  the  equation: 
water  vapor  content  =  relative  humidity  (%)  X  maximum 
capacity/ 1 00.  For  example,  if  a  heat  and  moisture  exchanger 


provides  32°  C  and  95%  relative  humidity,  then:  water 
vapor  content  =  (95  X  33.8)/100  =  32.1  mg  HjO/L. 


Normal  Mechanisms  of  Heat  and  Moisture  Exchange 
in  the  Respiratory  Tract 

During  normal  breathing,  the  upper  respiratory  tract 
warms,  humidifies,  and  filters  inspired  gases,  primarily  in 
the  nasopharynx,  where  gases  are  exposed  to  a  large  area 
of  highly  vascular,  moist  mucus  membrane.  The  orophar- 
ynx and  conducting  airways  also  contribute  to  this  process, 
but  are  less  efficient  because  they  lack  the  exquisite  ar- 
chitecture of  the  nose.  During  exhalation,  the  upper  air- 
ways reclaim  a  majority  of  the  heat  and  moisture  added 
during  inspiration.  Over  the  course  of  a  normal  day,  the 
respiratory  tract  loses  approximately  1470  J  of  heat  and 
250  mL  of  water.2  This  net  loss  of  heat  and  moisture  is 
predominantly  due  to  water  vapor  escaping  in  expired  gases. 
Little  heat  is  actually  lost  through  the  warming  of  inspired 
gas,  as  the  specific  heat  of  air  is  very  low. 

The  efficiency  of  the  normal  upper  airway  is  quite  re- 
markable. Even  at  extremes  of  inspired  temperature  and 
humidity,  gas  that  reaches  the  alveolar  level  is  100%  sat- 
urated at  body  temperature.^  Although  opinions  differ 
slightly,  it  is  generally  agreed  that  after  passing  through 
the  nasopharynx,  inspired  gases  are  at  29-32°  C  and  nearly 
100%  relative  humidity,  and  at  the  carina  gases  are  at 
32-34°  C  and  nearly  100%  relative  humidity.-*-" 

The  point  at  which  gases  reach  alveolar  conditions  (37° 
C  and  100%  relative  humidity)  is  known  as  the  isothermic 
saturation  boundary  (ISB).  Under  normal  conditions  the 
ISB  resides  in  the  fourth  to  fifth  generation  of  subsegmen- 
tal  bronchi.  The  position  of  the  ISB  is  fairly  constant,  even 
at  the  extremes  of  environmental  conditions.  Lung  disease 
and  fluid  status  can  also  affect  the  ISB.  Above  the  ISB,  the 
respiratory  tract  performs  the  function  of  a  countercurrent 
heat  and  moisture  exchanger.  Below  the  ISB,  temperature 
and  water  content  remain  relatively  constant. 

Following  intubation,  the  ISB  is  shifted  down  the  respi- 
ratory tract,  as  the  normal  upper  airway  heat  and  moisture 
exchanging  structures  are  bypassed  (Fig.  2).  This  places 
the  burden  of  heat  and  moisture  exchange  on  the  lower 
respiratory  tract,  a  task  for  which  it  is  poorly  suited.  The 
delivery  of  cold,  anhydrous  medical  gases  also  burdens  the 
lower  respiratory  tract  and  pushes  the  ISB  farther  down 
the  bronchial  tree.  The  combined  effects  of  intubation  and 
mechanical  ventilation  result  in  severe  losses  of  heat  and 
moisture  from  the  respiratory  mucosa,  and,  in  extreme 
cases,  damage  to  the  respiratory  epithelium.  This  includes 
functional  and  structural  changes  that  have  clinical  impli- 
cations.* ' 

The  provision  of  heat  and  humidity  during  mechanical 
ventilation  is  the  worldwide  standard  of  care  for  patients 


Respiratory  Care  •  June  1999  Vol  44  No  6 


631 


HUMIDIFICATION  FOR  PATIENTS  WITH  ARTIFICIAL  AlRWAYS 


E 


E 
X 


o 


0) 

E 
I- 


90 
80  -- 
70 
60  - 
50 
40  + 
30 


Absolute  Humidity 


o 
O 


83mg/L 


E 
o 

CO 


20 


Temperature 


O  ]  44mg/L 


Chamber 


Y-Piece  /  Patient 


zamij 


lfVe=10Umintiien 
565mL  of  condensate 
will  form  in  one  day. 


Fig.  1 .  Gas  cooling  and  condensate  formation  when  a  heated  humidity  generator  and 
unhealed  delivery  system  are  combined.  (From  Reference  1,  with  permission.) 


with  artificial  airways,'""  but  there  is  considerable  dis- 
agreement about  the  amount  of  humidity  to  provide  and 
how  best  to  provide  it.  The  methods  for  providing  humid- 
ity include  active,  microprocessor-controlled,  heat  and  hu- 
midifying systems  (heated  humidifiers)  and  simple,  pas- 
sive, heat  and  moisture  exchangers  (artificial  noses).  Table 
2  compares  the  advantages  and  disadvantages  of  the  hu- 
midification  devices  discussed  herein. 

High-Flow  Humidiflers 

High-flow  humidifiers  are  capable  of  providing  a  wide 
range  of  temperatures  and  humidities. '^  High-flow  humid- 
ifiers generically  consist  of  a  heating  element,  water  res- 
ervoir, temperature  control  unit  (including  temperature 
probe  and  alarms),  and  a  gas/liquid  interface  that  increases 
the  surface  area  for  evaporation.  Most  high-tlow  humidi- 
fiers fit  into  one  of  the  following  categories:  pass-over 
humidifiers,  wick  humidifiers,  or  bubble  humidifiers.  Be- 
cause these  devices  are  heated,  they  also  prevent  loss  of 
body  heat  from  the  patient,  which  is  particularly  important 
in  neonatal  applications.  When  heated  humidifiers  are  used, 
the  temperature  at  the  patient's  airway  should  be  moni- 
tored continuously  with  a  thermometer  or  thermistor.  It 
may  also  be  desirable  to  monitor  the  relative  humidity  at 
the  proximal  airway,  although  this  is  not  commonly  done. 


With  high-fiow  humidifiers,  the  water  level  in  the  res- 
ervoir can  be  maintained  manually,  by  adding  water  from 
a  bag  through  a  fill-set  attached  to  the  humidifier,  or  by  a 
float-feed  system  to  keep  the  water  level  constant.  Manual 
methods  tend  to  increase  the  risk  of  reservoir  contamina- 
tion and  pose  the  additional  risk  of  spilling  and  over- 
filling, so  fill-set  and  float-feed  systems  are  preferable. 
The  tloat-feed  systems  also  avoid  fluctuations  in  the  tem- 
perature of  gas  delivered,  which  occurs  when  cold  water  is 
added  to  the  humidifier. 

Most  humidifiers  are  servo-controlled;  that  is,  the  op- 
erator sets  the  desired  gas  temperature  at  the  thermistor, 
and  the  system  maintains  control  of  the  gas  temperature 
regardless  of  changes  in  gas  flow  or  reservoir  level.  These 
systems  are  equipped  with  audiovisual  alarms  to  warn  of 
high  temperature  conditions.  It  is  important  to  recognize 
that  the  thermistors  in  these  systems  have  a  relatively  slow 
response  and  only  reflect  the  average  temperature  of  the 
inspired  gas.  Actual  temperatures  may  fluctuate  above  and 
below  the  average  temperature  with  cyclic  gas  flow,  as 
may  occur  in  a  mechanical  ventilator  circuit. 

In  recent  years  it  has  become  popular  to  heat  the  tubing 
that  carries  gas  from  the  humidifier  to  the  patient.  These 
circuits  contain  electric  wires  that  heat  the  gas  as  it  traverses 
the  heated  ventilator  wire  circuit.  Heated  wire  circuits  pro- 
vide a  more  precise  gas  temperature  delivered  to  the  pa- 


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HUMIDIFICATION  FOR  PATIENTS  WITH  ARTIFICIAL  AlRWAYS 


ISB  during  normal 
nose  breathing 


ISB  during  dry  gas 
(eg,  anesthetic) 


Fig.  2.  Position  of  the  isothermic  saturation  boundary  (ISB)  during 
normal  nose  breathing  and  during  inhalation  of  dry  gases  (during 
intubation). 

tient  and  prevent  condensation  of  water  in  the  tubing.  The 
temperature  of  the  wire  can  be  controlled  by  the  humidi- 
fier temperature  control — or  separately.  If  the  temperature 
of  the  heating  wires  is  controlled  separately  from  the  hu- 
midifier, this  can  affect  the  relative  humidity  delivered  to 
the  patient.  If  the  temperature  of  the  tubing  is  greater  than 
the  temperature  of  the  gas  leaving  the  humidifier,  then  the 
relative  humidity  of  the  gas  decreases,  which  can  result  in 
drying  of  secretions  and  endotracheal  tube  obstruction.'^ 
On  the  other  hand,  if  the  temperature  of  the  tubing  is  lower 
than  the  temperature  of  the  gas  leaving  the  humidifier, 
condensation  will  occur  in  the  tubing. 

The  use  of  servo-controlled  heated-wire  circuits  can  be- 
come complex  when  the  gas  is  delivered  to  a  neonate  in  an 
incubator  or  under  a  radiant  heater.'-^  The  problem  is  that 
the  delivered  gas  is  exposed  to  2  temperatures:  room  tem- 
perature and  the  temperature  in  the  incubator  (or  under  the 
radiant  heater).  In  these  applications,  the  thermistor  should 
be  placed  directly  outside  the  incubator  (or  out  from  under 
the  radiant  heater)  rather  than  at  the  proximal  airway  of  the 
patient. 

In  systems  that  do  not  use  heated  wire  circuits,  water 
that  collects  in  the  tubing  is  a  potential  source  of  nosoco- 


mial infection.  Water  in  the  tubing  can  also  result  in  ac- 
cidental airway  lavage  during  turning.  Water  that  con- 
denses in  the  tubing  can  be  collected  in  a  water  trap.  This 
water  should  be  considered  contaminated  and  should  never 
be  allowed  to  drain  back  into  the  humidifier. 

Pass-over  Humidifiers 

In  a  pass-over  humidifier,  gas  from  the  ventilator  is 
introduced  into  the  humidifier  chamber,  passes  over  the 
surface  of  the  water  reservoir,  and  exits  to  the  ventilator 
circuit.  This  is  the  simplest  form  of  heated  humidifier. 

Wick  Humidifiers 

The  wick  humidifier  is  a  variation  of  the  pass-over  hu- 
midifier. In  the  wick  humidifier,  gas  enters  a  cylinder  that 
is  lined  with  a  wick  of  blotter  paper.  The  wick  is  sur- 
rounded by  a  heating  element  and  the  base  of  the  wick  is 
immersed  in  water.  As  the  gas  passes  the  moist,  heated 
wick,  the  relative  humidity  of  the  gas  increases. 

Bubble  Humidifiers 

In  a  bubble  humidifier,  gas  from  the  ventilator  is  di- 
rected through  a  tube  submerged  in  a  water  reservoir.  The 
gas  bubbles  through  the  water,  through  a  diffuser  or  grid, 
and  enters  the  ventilator  circuit.  One  type  of  bubble  hu- 
midifier is  the  cascade-type  humidifier,  in  which  gas  from 
the  ventilator  passes  through  a  submerged  grid,  creating  a 
froth  of  small  bubbles.  Humidifier  temperature  is  main- 
tained by  a  thermostat,  and  a  thermometer  or  thermistor  at 
the  patient's  airway  monitors  the  temperature  of  the  gas 
delivered.  Unless  the  tubing  between  the  humidifier  and 
the  patient  is  heated,  the  gas  temperature  decreases  as  it 
moves  downstream  of  the  humidifier,  resulting  in  conden- 
sation. Although  the  cascade-type  humidifier  efficiently 
delivers  water  vapor,  it  may  also  deliver  microaerosols 
that  can  transmit  bacteria  if  the  reservoir  becomes  con- 
taminated.'-'' However,  the  temperature  in  the  water  reser- 
voir inhibits  the  growth  of  pathogens. 'f' 

Artificial  Noses 

Artificial  nose  is  a  generic  term  used  to  describe  a  group 
of  similar  humidification  devices.  The  term  artificial  nose 
comes  from  the  similarity  in  function  to  the  human  nose. 
By  definition,  an  artificial  nose  is  a  passively  acting  hu- 
midifier that  collects  the  patient's  expired  heat  and  mois- 
ture and  returns  it  during  the  following  inspiration.  These 
devices  are  also  collectively  referred  to  as  passive  humid- 
ifiers, a  term  that  is  more  specific  to  function. '- 

There  are  several  types  of  artificial  noses.  Heat  and 
moisture  exchangers  (HMEs)  use  only  physical  principles 


Respiratory  Care  •  June  1999  Vol  44  No  6 


633 


HUMIDIFICATION  FOR  PATIENTS  WITH  ARTIFICIAL  AlRWAYS 


Table  2.      Advantages  and  Disadvantages  of  Humidification  Devices 


Device 


Advantages 


Disadvantages 


Heated  humidifier 


Artificial  nose 


Active  heat  and  moisture  exchanger 


HME-Booster 


Universal  application  (neonates  to  adults) 

Wide  range  of  temperature  and  humidity 

Alarms 

Safety 

Temperature  monitoring 

Reliability 

Elimination  of  condensate  with  heated  wire  circuit 

Cost 

Passive  operation 

Simple  use 

Elimination  of  condensate 

Portable 

Elimination  of  condensate 

Reduced  water  usage 

Minimum  output  always  provided 

Eliminates  water  loss  from  the  respiratory  tract 

Temperature  monitoring 

Simple 

Inexpensive 

Improves  heat  and  moisture  exchanger  performance  by 

2-^  mg  H,0/L 
Reduced  water  usage 
Minimum  output  always  provided 


Cost 

Water  usage 

Condensation  '. 

Risk  of  circuit  contamination 

Over  heating 

Small  risk  of  burns/electric  shock 

Colonization  of  chamber  (heated  wire  circuit) 

Not  applicable  in  all  patients 

Increased  dead  space  . 

Increased  resistance 

Potential  for  occlusion 

Potential  for  occlusion 

Additional  weight  on  endotracheal  tube 

Increased  dead  space 

Increased  resistance 

Small  risk  of  burns/electric  shock 

Small  improvement  in  moisture  output  may  not  be 

worth  additional  cost 
No  temperature  monitoring 
Small  increase  in  dead  space 
Increased  resistance 
Potential  for  occlusion 
Small  risk  of  burns/electric  shock 


of  heat  and  moisture  exchange.  The  addition  of  a  filter  to 
an  HME  results  in  a  heat  and  moisture  exchanging  filter 
(HMEF).  Hygroscopically  treated  devices  are  called  hy- 
groscopic heat  and  moisture  exchangers  (HHME),  or,  if 
the  device  if  fitted  with  a  filter,  it  is  called  a  hygroscopic 
heat  and  moisture  exchanger  filter  (HHMEF). 

The  HME  is  the  simplest  of  these  devices  and  was  the 
first  passive  humidifier  introduced.  An  HME  usually  con- 
sists of  a  layered  aluminum  insert  with  or  without  an  ad- 
ditional fibrous  element.  Aluminum  exchanges  tempera- 
ture quickly,  and  during  expiration  condensation  forms 
between  the  aluminum  layers.  The  retained  heat  and  mois- 
ture are  returned  during  inspiration.  The  addition  of  a  fi- 
brous element  aids  in  the  retention  of  moisture  and  helps 
reduce  pooling  of  condensate  in  the  dependent  portions  of 
the  device.  HMEs  are  the  least  efficient  passive  humidifi- 
ers and  are  not  often  used.  These  devices  tend  to  be  cheaper 
than  other  passive  humidifiers  and  may  be  used  in  the 
operating  room  for  short-term  humidification.  These  de- 
vices have  a  nominal  moisture  output,  providing  10-14 
mg  HjO/L  at  tidal  volumes  (Vt)  of  500-1000  mL.'^'** 

HMEFs  are  fitted  with  a  spun  and  pleated  filter  media 
insert,  over  and  through  which  the  inhaled/exhaled  gas 
passes.  Laboratory  evaluations  of  these  devices  indicate  a 
moisture  output  of  18-28  mg  HjO/L  at  V-r  of  500-1000 
mL.'«--« 


The  HHME  is  the  most  popular  style  of  artificial  nose. 
These  devices  vary  widely  in  shape,  size,  and  type  of 
media  insert.  Most  HHMEs  use  a  paper  or  polypropylene 
insert  treated  with  a  hygroscopic  chemical,  usually  cal- 
cium or  lithium  chloride,  to  enhance  moisture  conserva- 
tion. Comparative  studies  have  shown  that  HHMEs  can 
provide  a  moisture  output  of  22-34  mg  HjO/L  at  V^  of 
500-1000  mL.  The  addition  of  a  filter  media  to  an  HHME 
creates  an  HHMEF. '^  The  filter  media  is  typically  placed 
between  the  ventilator  connection  and  the  HHMEF' s  me- 
dia insert.  This  places  the  hygroscopically-treated  material 
between  the  patient's  expired  gas  and  the  filter.  Typical 
filtration  material  is  made  from  spun  polypropylene,  which 
is  electrostatically-charged,  attracting  airborne  materials 
and  trapping  them  in  the  media.  This  filter  is  poorly  suited 
as  a  heat  and  moisture  exchanging  media,  but  when  com- 
bined with  the  hygroscopic  element,  appears  to  increase 
moisture  output  by  1-2  mg  HiO/L.'^--**  Note  that  the  pres- 
ence of  the  filter  also  increases  the  resistance  of  the  device. 

Moisture  Output 

The  amount  of  heat  and  humidity  provided  by  an  arti- 
ficial nose  is  typically  referred  to  as  moisture  output.  Mois- 
ture output  is  measured  under  laboratory  conditions  and 
reported  in  mg  HjO/L.  There  are  currently  no  standards 


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HUMIDIFICATION  FOR  PATIENTS  WITH  ArTIHCIAL  AiRWAYS 


for  the  minimum  moisture  output  of  an  artificial  nose.  The 
standard  for  heated  humidifiers  suggests  a  minimum  of  33 
mg  HjO/L.^''  AppHcation  of  this  standard  to  HME  and 
HHME  is  not  very  helpful.  The  American  Association  for 
Respiratory  Care  recommends  that  the  required  moisture 
output  be  determined  relative  to  the  application  and  dura- 
tion of  use.'"  For  example,  a  patient  with  normal  respira- 
tory function  requiring  intubation  for  a  2-hour  operative 
procedure  probably  only  requires  15-20  mg  HjO/L.  Me- 
chanically ventilated  patients  with  normal  secretions  ap- 
pear to  require  a  minimum  of  26  mg  H2O/L  to  prevent 
drying  of  secretions  and  to  maintain  mucociliary  function. 
Patients  with  increased  secretion  production  probably  re- 
quire additional  heat  and  moisture  that  an  artificial  nose 
cannot  supply.  Heated  humidification  should  be  used  in 
patients  with  thick  or  copious  sputum. 

The  moisture  output  reported  in  an  HME's  package  in- 
sert is  based  on  a  certain  V-p,  inspiratory  time,  respiratory 
rate,  and  temperature,^"  and  clinicians  should  bear  in  mind 
that  the  actual  moisture  output  varies  in  relation  to  those 
factors.  As  V^  increases,  moisture  output  decreases.  The 
amount  of  the  decrease  depends  on  the  efficiency  of  the 
device  and  the  dead  space.  Larger  devices  tend  to  be  less 
affected  by  an  increase  in  V^  because  of  rebreathing.  That 
is,  if  an  HME  with  an  internal  volume  of  100  mL  is  used, 
100  mL  of  each  inspiration  will  contain  expired  gases.  An 
increase  in  respiratory  rate  or  decrease  in  inspiratory  time 
will  also  decrease  moisture  output.  Likewise,  an  increase 
in  expiratory  flow  due  to  a  decrease  in  lung  compliance 
also  decreases  moisture  output.  In  each  of  these  instances, 
the  decrease  in  transit  time  (gas  moves  through  the  media 
more  quickly)  reduces  the  ability  of  the  device  to  remove 
moisture  from  exhaled  gas  and  add  moisture  to  inspired 
gas."  Remember,  when  using  an  artificial  nose  there  is 
always  a  net  heat  and  moisture  loss  from  the  respiratory 
tract. 

The  International  Standards  Organization  testing  of  and 
standards  for  artificial  noses'"'  use  a  model  to  simulate 
patient  expiration  of  warm,  humidified  gas.  The  model 
assumes  a  constant  output  regardless  of  the  minute  venti- 
lation, inspired  gas  temperature,  or  efficiency  of  the  device 
tested.  The  devices  are  tested  at  V^-  of  500  mL  and  1000 
mL,  and  at  respiratory  frequencies  of  10  and  20  breaths  per 
min.  The  moisture  output  listed  on  the  package  insert  re- 
flects the  results  of  this  controlled,  laboratory  testing,  and 
the  actual  clinical  performance  varies  with  patient  temper- 
ature, minute  ventilation,  Vj,  inspiratory-expiratory  ratio, 
and  patient  lung  health.  Most  investigators  agree  that  the 
accuracy  is  ±2  mg  HjO/L. 

Resistance 

Resistance  to  gas  flow  in  an  artificial  nose  increases  as 
media  density  increases  and  as  dead  space  decreases.  This 


increase  in  resistance  can  adversely  affect  the  patient's 
work  of  breathing.^- ''■'  However,  compared  to  the  added 
resistance  of  the  endotracheal  tube,  this  increase  is  small. 
Most  devices  currently  manufactured  have  a  resistance 
<  3.5  cm  H2O.  During  use,  as  the  media  absorbs  water, 
resistance  increases  slightly.  After  prolonged  use,  the  in- 
crease in  resistance  to  expiratory  flow  may  cause  air-trap- 
ping and  auto-positive  end-expiratory  pressure  (auto- 
PEEP). 

The  greatest  concern  about  increased  HHME  resistance 
is  that  the  media  can  become  occluded  with  secretions, 
blood,  or  water  from  a  secondary  source.  Several  research- 
ers have  reported  an  increase  in  resistance  because  of  wa- 
ter and  blood  accumulating  in  the  media.'''  -•-  In  one  in- 
stance, saline  (intended  to  aid  in  loosening  secretions  prior 
to  suctioning)  accumulated  in  the  HHME  media.-*'  Aero- 
solized drugs  can  also  increase  resistance  if  the  drug  or  its 
carrier  collects  in  the  media  or  filter.  The  artificial  nose 
should  be  removed  from  the  airway  prior  to  delivery  of 
aerosolized  medications.  During  mechanical  ventilation, 
the  need  for  frequent  aerosol  treatments  may  necessitate 
switching  to  heated  humidification. 

Manufacturing  defects  that  have  resulted  in  total  or  par- 
tial occlusion  of  artificial  noses  have  been  reported  in  3 
separate  instances.-*"*  '*''  In  each  case,  a  remnant  from  the 
plastic  housing  remained  in  the  path  of  gas  flow.  Clini- 
cians should  visually  inspect  each  device  prior  to  use. 

Dead  Space 

Placing  an  artificial  nose  on  the  end  of  the  patient's 
airway  increases  dead  space.  In  order  to  maintain  normal 
alveolar  ventilation,  respiratory  rate,  V^.  or  both  must  in- 
crease, or  arterial  carbon  dioxide  will  increase.  This  effect 
is  most  pronounced  in  spontaneously  breathing  patients, 
and  is  a  function  of  the  relationship  between  V.,  and  dead 
space.  Consider  this  example:  a  70  kg  patient  with  a  spon- 
taneous Vy  of  400  mL  and  a  respiratory  rate  of  15  breaths 
per  min  has  a  minute  ventilation  of  6.0  L/min.  If  the  pa- 
tient's anatomic  dead  space  is  150  mL,  then  alveolar  ven- 
tilation will  be:  15  breaths/min  X  (400  mL  -  150  mL)  = 
3.75  L/min. 

If  an  HME  with  a  dead  space  of  100  mL  is  added  to  the 
airway  and  minute  ventilation  is  unchanged  (6.0  L/min), 
alveolar  ventilation  decreases  to:  15  X  400  mL  -  (150  mL 
+  100  mL)  =  2.25  L/min. 

In  order  to  restore  alveolar  ventilation  to  3.75  L/min, 
minute  ventilation  must  increase  via  an  increase  in  respi- 
ratory rate,  V^,  or  both:  15  X  500  mL  -  (150  mL  -f  100 
mL)  =  3.75  L/min  and  minute  ventilation  =  7.5  L/min. 

Several  authors  have  observed  the  adverse  effects  of 
added  dead  space  on  respiratory  mechanics.-*''-''^  In  each 
report  the  addition  of  an  HME  or  HHME  with  a  dead 
space  of  100  mL  resulted  in  an  increase  in  the  work  of 


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635 


HUMIDIFICATION  FOR  PATIENTS  WITH  ARTIFICIAL  AlRWAYS 


breathing,  an  increase  in  the  required  minute  ventilation, 
and  an  increase  in  auto-PEEP.  When  patients  were  able  to 
increase  respiratory  rate  and/or  V-p,  arterial  CO2  remained 
constant.  When  patients  were  unable  to  increase  minute 
ventilation  (weak  respiratory  muscles),  arterial  COj  con- 
centrations increased.  Pressure  support  ventilation  can  be 
used  to  overcome  the  additional  work  of  breathing,  but  can 
also  lead  to  higher  airway  pressures  and  increased  auto- 
PEEP.  When  choosing  an  artificial  nose,  select  the  device 
that  provides  adequate  humidification  while  increasing 
dead  space  as  little  as  possible. 

Additives 

To  increase  moisture  output,  HHMEs  utilize  either  cal- 
cium chloride  or  lithium  chloride  as  hygroscopic  additives. 
Some  manufacturers  also  add  chlorohexadine  as  a  bacte- 
riostatic treatment.  Lithium,  delivered  by  mouth  or  injec- 
tion, is  used  in  the  treatment  of  certain  psychological  dis- 
orders, including  depression  and  mania.  It  has  been 
suggested,  though  not  yet  demonstrated,  that  lithium  from 
HHME  media  might  be  released  into  the  trachea  and  ab- 
sorbed into  the  bloodstream  at  a  therapeutic  concentra- 
tion.^osi  The  only  report  of  a  patient  seen  to  have  elevated 
serum  lithium  levels  while  using  an  HHME  was  of  a  pa- 
tient who  had  also  taken  lithium  orally  prior  to  admission 
to  the  hospital.  The  small  amount  of  lithium  in  these  de- 
vices appears  to  make  this  concern  unwarranted. 

Cost 

Cost  is  an  important  feature  of  any  medical  equipment. 
At  present  the  average  cost  of  an  HHME  is  $3.25,  though 
the  range  of  costs  is  wide  ($1.95  to  $5.75),  with  HHMEFs 
and  HMEFs  being  the  most  expensive  devices. 

Choosing  an  Artificial  Nose 

In  the  intensive  care  unit  (ICU)  setting,  the  most  im- 
portant factors  regarding  an  artificial  nose  are  moisture 
output,  dead  space,  resistance,  and  cost.  I  believe  an  ac- 
ceptable artificial  nose  should  have  a  minimum  moisture 
output  of  28  mg  H2O/L,  a  dead  space  of  <  50  mL,  a 
resistance  of  <  2.5  cm  HjO/L/s,  and  a  price  <  $2.50.  For 
short-term  use  in  the  operating  room,  where  patients  are 
paralyzed,  dead  space  is  a  less  important  issue.  Also,  be- 
cause most  patients  in  the  operating  room  require  only 
several  hours  of  ventilatory  support,  the  minimum  mois- 
ture output  requirement  can  be  reduced  in  some  cases. 
Similarly,  the  dead  space  recommendation  may  vary  with 
respect  to  the  patient's  Vy. 


Fig.  3.  Schematic  diagram  of  an  active  heat  and  moisture  ex- 
changer, the  Humid-Heat  (Gibeck  AB,  Sweden). 

Active  Hygroscopic  Heat  and  Moisture  Exchangers 

Artificial  noses  cannot  be  used  in  all  situations,  since 
some  patients  require  the  addition  of  heat  and  moisture  to 
the  respiratory  tract.  In  an  effort  to  expand  the  use  of 
HHME,  Gibeck-Dryden  (Gibeck  AB,  Sweden)  has  intro- 
duced the  active  HHME  (Fig.  3),  which  incorporates  an 
HHME  into  a  heated  housing.  The  housing  contains  a 
paper  element  that  acts  as  a  wick  to  provide  the  surface 
area  for  gas/moisture  transfer.  A  water  source  continu- 
ously drips  water  onto  the  paper  element,  and  the  heat 
from  the  housing  causes  the  water  to  evaporate,  thereby 
increasing  the  humidity  of  the  gas.  This  system  works 
much  like  a  wick  humidifier,  except  that  the  source  of  heat 
and  moisture  is  added  at  the  airway.  This  eliminates  con- 
densate in  the  inspiratory  limb  and  thus  obviates  the  water 
trap.  In  addition,  if  the  water  source  runs  out,  this  device 
continues  to  operate  as  an  HHME.  Thus,  there  is  never  the 
possibility  of  delivering  dry  gas  to  the  airway,  as  can  occur 
with  a  traditional  heated  humidifier. 

In  a  recent  evaluation,  we  found  that  the  active  HHME 
provided  temperatures  of  36-38°  C  and  90-95%  relative 
humidity.  Compared  to  a  heated  humidifier  and  to  a  heated 
humidifier  with  a  heated  wire  circuit,  the  active  HHME 
provided  equivalent  efficiency  with  lower  water  usage. 
The  disadvantages  of  this  product  are  the  potential  for  skin 
bums  and  the  increase  in  dead  space  compared  to  a  heated 
humidifier  or  HHME  alone.  The  external  temperature  of 
the  housing  is  near  37°  C.  Under  normal  conditions  this 
temperature  is  safe.  However,  patients  with  peripheral 
edema  or  low  cardiac  output  may  have  reduced  blood 
flow  to  the  skin,  in  which  case  heat  transfer  is  reduced  and 
even  modest  temperatures  can  cause  local  burns.  The  ex- 
perience with  this  device  is  presently  scant  and  further 
studies  are  needed  to  determine  if  this  device  provides 
any  additional  benefit  compared  to  conventional  heated 
humidifiers.-^- 


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HUMIDIFICATION  FOR  PATIENTS  WITH  ARTIFICIAL  AlRWAYS 


Fig.  4.  The  HME  (heat  and  moisture  exchanger)  Booster.  (Courtesy  of  TomTec,  Belgium). 


HME-Booster 

The  HME-Booster  (TomTec,  Belgium)  is  similar  in  con- 
cept to  an  active  HME,  but  simpler  and  less  efficient.  The 
booster  is  a  small  heating  element  placed  between  the 
passive  humidifier  and  the  patient.  The  heating  element  is 
covered  with  a  Gore-Tex  membrane.  Water  flows  onto  the 
surface  of  the  heating  element  and  is  vaporized,  then  passes 
through  the  membrane  and  is  delivered  to  the  patient  dur- 
ing inspiration  (Fig.  4).  During  expiration,  the  additional 
moisture  is  trapped  in  the  passive  humidifier,  serving  to 
load  the  media  with  moisture.  Some  of  the  moisture  es- 
capes through  the  HME.  The  water  flow  is  controlled  by  a 
pin-hole-sized  orifice  adjacent  to  the  heating  element.  This 
prevents  pooling  of  excess  water.  Reports  of  the  booster's 
use  are  scant.'"''  Our  laboratory  experience  suggests  that 
the  device  can  add  an  additional  3-4  mg  HjO/L  to  in- 
spired gases,  depending  on  the  Vy,  inspiratory-expiratory 
ratio,  and  type  of  passive  humidifier  used.  Whether  this 
small  increase  in  moisture  output  is  worth  the  additional 
equipment  and  expense  remains  to  be  seen.''^ 


Use  of  Humidification  Devices  During 
Mechanical  Ventilation 

Clinicians  should  bear  in  mind  that  even  the  most  effi- 
cient artificial  noses  return  only  70-80%  of  the  patient's 
expired  humidity,  so  use  of  an  artificial  nose  always  in- 


volves a  net  loss  of  heat  and  moisture.  Artificial  noses  are 
not  as  efficient  as  heated  humidification  devices  and  should 
be  used  after  evaluation  of  the  patient's  humidification 
needs.  Figure  5  shows  an  algorithm  for  safe  and  judicious 
use  of  artificial  noses  in  the  ICU.^-*  This  protocol  uses 
contraindications  to  artificial  nose  use  to  advise  practitio- 
ners when  to  use  heated  humidification.  Contraindications 
to  artificial  nose  use  include  the  presence  of  thick,  copious 
sputum,  grossly  bloody  secretions,  and  hypothermia  (< 
32°  C). 

Artificial  noses  are  attractive  alternatives  to  heated  hu- 
midifiers because  of  their  low  cost,  passive  operation  and 
ease  of  use,  but  not  all  patients  can  use  an  artificial  nose. 
Patients  with  preexisting  pulmonary  disease  characterized 
by  thick,  copious,  or  bloody  secretions  should  receive 
heated  humidification,  because  secretions  and  blood  can 
occlude  the  media  or  filter  and  result  in  excessive  resis- 
tance, air  trapping,  hypoventilation,  and  possibly  baro- 
trauma. Because  artificial  noses  only  return  a  portion  of 
the  heat  and  moisture  exhaled,  patients  with  hypothermia 
should  receive  heated  humidification.  If  patient  body  tem- 
perature is  32°  C  (absolute  humidity  of  32  mg  HjO/L), 
even  a  very  efficient  HHME  (80%  moisture  returned),  can 
only  deliver  an  absolute  humidity  of  25.6  mg  HjO/L.  A 
patient  with  a  bronchopleural  fistula  or  incompetent  tra- 
cheal tube  cuff  should  also  not  use  passive  humidifiers. 
Because  the  device  relies  on  collecting  expired  heat  and 
moisture,  any  problem  that  allows  expired  gas  to  escape  to 


Respiratory  Care  •  June  1999  Vol  44  No  6 


637 


HUMIDIFICATION  FOR  PATIENTS  WITH  ARTIFICIAL  AlRWAYS 


Examine  patient 
History/pliysical 
findings 


Bloody  secretions? 
Thicl<  tenacious 
sputum? 

Core  temperature 
<32''C 


Yes 


No 


Hygroscopic 
condenser 
humidifier 
(Replace  q  24  h) 


Evaluate  secretion 
quality  and  quantity 
Examine  patient 


No 


^H 


Are  >  4  HCHs  used  per 
24  h? 


Yes 


Heated  tiumidification 
32-34°  C  and  100%  RH 
at  proximal  airway 


Fig.  5.  Algorithm  to  determine  the  safe  use  of  a  passive  humidifier. 
RH  =  relative  humidity.  HCH  =  hygroscopic  condenser  humidifier. 
(Adapted  from  Reference  54.) 


the  atmosphere  without  passing  through  the  media  will 
reduce  humidity. 

Passive  humidifiers  should  never  be  used  in  conjunction 
with  heated  humidifiers.  Particulate  water  in  the  media 
increases  resistance  and  prevents  adequate  delivery  of  hu- 
midity from  either  device.  If  water  occludes  the  filter,  the 
patient  cannot  be  adequately  ventilated  and  may  be  unable 
to  completely  exhale  during  positive  pressure  ventilation. 
Delivery  of  aerosolized  bronchodilators  using  a  small  vol- 
ume nebulizer  requires  that  the  HME  be  taken  out  of  line, 
and  this  frequent  breaking  of  the  circuit  increases  the  risk 
of  circuit  contamination.  Thus,  patients  requiring  frequent 
medication  delivery  via  a  small  volume  nebulizer  should 
not  use  an  HME.  A  metered  dose  inhaler  (MDI)  can  be 
used  with  an  HME  if  the  MDI  adapter  is  placed  between 
the  HME  and  the  endotracheal  tube.  If  spacer  devices  are 
used  in  the  inspiratory  limb,  the  HME  should  be  taken  out 
of  line.  A  patient  requiring  frequent  use  of  an  MDI  or  other 
aerosol  therapy  might  be  better  served  by  a  heated  humid- 
ification  system. 

In  the  ICU,  an  artificial  nose  can  be  used  for  extended 
periods;  our  experience  suggests  that  5  days  is  safe  and 
effective.  This  recommendation  is  based  on  numerous  stud- 
ies that  have  found  that  partial  or  complete  obstruction  of 
endotracheal  tubes  appears  to  occur  around  5  days.-'"'-''* 
Patient  sputum  characteristics  should  be  assessed  with 
every  suctioning  attempt.  If  the  secretions  appear  thick 
on  2  consecutive  suctioning  procedures,  the  patient  should 
be  switched  to  a  heated  humidifier.  We  recommend  Su- 
zukawa's  method''^  forjudging  the  quality  of  sputum,  as 
follows: 


Thin:  The  suction  catheter  is  clear  of  secretions  follow- 
ing suctioning. 

Moderate:  After  suctioning,  the  suction  catheter  has 
secretions  adhering  to  the  sides,  but  the  adhering  secre- 
tions are  easily  removed  by  aspirating  water  through  the 
catheter. 

Thick:  After  suctioning,  the  suction  catheter  has  secre- 
tions adhering  to  the  sides,  and  the  adhering  secretions  are 
not  removed  by  aspirating  water  through  the  catheter. 

Recent  work  has  suggested  that  the  presence  of  conden- 
sate in  the  elbow  or  flex  tube  between  the  HME  and  the 
patient  implies  adequate  humidification.^"  This  makes 
sense,  because  the  presence  of  condensate  suggests  that 
the  gases  are  saturated  with  water  vapor.  This  observable 
condensate  criteria  should  help  clinicians  decide  on  a  case- 
by-case  basis  the  advisability  of  switching  the  patient  from 
an  artificial  nose  to  a  heated  humidifier.  However,  artifi- 
cial noses  have  been  used  for  up  to  30  days.*' 

Other  methods  of  determining  humidifier  efficiency  in- 
volve fairly  complex  techniques,  including  radioactive  iso- 
topes and  bronchoscopic  evaluation.  For  the  clinician,  spu- 
tum consistency  and  the  presence  of  condensate  in  the  flex 
tube  are  the  most  readily  available  means. 

We  believe  patients  requiring  mechanical  ventilation  for 
greater  than  5  days  are,  by  definition,  critically  ill.  At  day 
5,  if  lung  function  has  not  improved,  heated  humidifica- 
tion  should  be  considered  to  prevent  secretion  retention 
and  to  maximize  mucociliary  function.  If  the  patient  be- 
gins the  weaning  process  at  day  5,  the  added  dead  space 
and  resistance  of  the  artificial  nose  may  hinder  spontane- 
ous breathing.  This  point  may  be  debated,  but  we  believe 
it  represents  the  best  compromise  between  cost  efficiency, 
humidification  efficiency,  and  patient  safety.  Using  the 
clinical  evaluation  of  humidification  performance  may 
allow  the  5-day  time  period  to  be  extended  for  certain 
patients. 

Most  manufacturers  suggest  artificial  noses  be  changed 
every  24  hours,  but  recent  research  indicates  that  if  the 
device  remains  free  of  secretions,  the  change  interval  can 
be  increased  to  every  48  or  72  hours  without  adverse  ef- 
fect.^^-64  jj^jj;  requires  that  respiratory  therapists  inspect 
for  secretions  frequently  and  change  the  device  as  required. 
If  the  device  is  contaminated  frequently  by  secretions  and 
requires  >  3  changes  daily,  the  patient  should  be  switched 
to  heated  humidification.  The  frequent  soiling  of  the  de- 
vice suggests  that  the  patient  has  a  secretion  problem  and 
the  frequent  changes  will  negate  any  cost  savings. 

Early  work  suggested  that  the  use  of  passive  humidifiers 
might  decrease  the  incidence  of  nosocomial  pneumonia. 
However,  no  reliable  evidence  supports  this  conclusion.  In 
fact,  artificial  noses  in  patients  with  bacteria  in  their  spu- 
tum readily  become  colonized.  If  there  is  no  sputum  con- 
tamination of  the  media,  however,  replication  of  bacteria 
appears  controlled.'''' 


638 


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HUMIDIFICATION  FOR  PATIENTS  WITH  ARTIFICIAL  AlRWAYS 


Fig.  6.  A  heat  and  moisture  exchanger  (HME)  for  the  laryngectomy 
patient. 


Patients  requiring  tracheostomy  and  prolonged  mechan- 
ical ventilation  in  subacute  care  hospitals  and  long-term 
care  facilities  may  use  artificial  noses  for  much  longer 
periods.  The  maximum  duration  has  yet  to  be  determined. 
There  are  several  reasons  for  this  prolonged  use.  Patients 
requiring  tracheostomy  have  their  upper  airway  perma- 
nently bypas.sed  and  the  morphologic  structure  of  the  lower 
airway  may  adapt  to  provide  greater  heat  and  moisture 
exchange  capabilities.  Additionally,  many  of  these  patients 
have  chronic  diseases  and  are  not  subject  to  the  multitude 
of  homeostasis  problems  seen  in  the  hospital.  The  decision 
to  use  heated  humidification  in  this  setting  should,  how- 
ever, be  similar  to  that  described  previously. 

Use  of  Heated  Humidification 

I  believe  that  the  ideal  inspired  gas  conditions  are  32- 
34°  C  and  100%  relative  humidity.  Heated  humidifiers 
without  heated  wire  circuits  use  more  water,  produce  more 
condensate,  and  are  more  expensive  with  time,  compared 
to  use  with  a  heated  wire  circuit.''''  Heated  wire  circuits 
eliminate  condensate,  reduce  water  usage,  and  decrease 
cost,  and  ventilator  operation  is  more  efficient  if  conden- 
sation is  prevented.  The  longer  the  heated  wire  circuit  is 
used,  the  greater  the  cost  savings.  The  initial  investment  of 
heated  wire  circuits  is  greater,  but  if  used  for  patients 
requiring  long-term  support,  heated  wire  circuit  costs  ap- 
proach the  costs  of  HME  use  over  a  period  of  about  a 
week.^-''  There  are  no  proven  advantages  to  the  patient 
when  using  a  heated  wire  circuit  versus  a  nonheated  wire 
circuit.  The  choice  is  generally  one  of  clinician  preference 
and  cost. 


Use  by  Ambulatory  Patients 

Patients  who  require  long-term  tracheostomy  or  trache- 
ostoma  for  upper  airway  disease  may  also  benefit  from  use 
of  artificial  noses.  The  device  not  only  aids  in  maintaining 
humidity,  but  also  serves  as  a  filter  to  prevent  the  inhala- 
tion of  large  particles  of  dust  and  other  airborne  debris 
(Fig.  6).  Several  authors  have  shown  that  use  of  an  HHME 
in  patients  with  tracheostoma  reduces  sputum  production 
and  number  of  coughing  episodes  per  day .''''"'''*  To  clini- 
cians these  findings  are  not  particularly  striking,  but  can  be 
important  to  the  patient's  quality  of  life.  A  patient  who 
typically  has  15-20  coughing  episodes  per  day  to  expec- 
torate sputum  through  the  stoma  can  realize  a  reduction  to 
10-12  episodes  with  use  of  an  artificial  nose.  This  allows 
the  patient  improved  sleep  habits  and  greater  confidence  in 
traveling  outside  the  home. 

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16.  Goularte  TA,  Manning  MT,  Craven  DE.  Bacterial  colonization  in 
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49.  Le  Bourdelles  G,  Mier  L,  Fiquet  B.  Djedaini  K,  Saunion  G,  Coste  F, 
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50.  Rathberger  J.  Zielman  S,  Kietzman  D,  Zuchner  K,  Warnecke  G.  [Is 
the  use  of  lithium  chloride  coated  "Heat  and  Moisture  Exchangers" 
(artificial  noses)  dangerous  for  patients?]  Der  Anaesthesist  1992;41: 
204-207. 

5 1 .  Rosi  R,  Buscalferri  A.  Monfregola  MR.  Crisuolo  S.  Dal  Pra  P,  Stanca 
A.  Systemic  lithium  reabsorption  from  lithium-chloride-coated  heat  and 
moisture  exchangers.  Intensive  Care  Med  1995;21(1 1):937-940. 

52.  Branson  RD,  Campbell  RS,  Davis  K  Jr,  Ottaway  M,  Johannigman 
JA.  Comparison  of  a  new  active  heat  and  moisture  exchanger  to 
conventional  heated  humidification.  Respir  Care  (1999,  in  press). 

53.  Branson  RD.  Campbell  RS.  Johanniginan  JA.  Davis  K  Jr.  Fraine  SB. 
A  comparison  of  two  novel  methods  of  humidification  (abstract). 
Crit  Care  Med  1999;27;A70. 

54.  Branson  RD,  Davis  K,  Campbell  RS,  Johnson  DJ.  Porembka  DT. 
Humidification  in  the  intensive  care  unit.  Praspective  study  of  a  new 
protocol  utilizing  heated  humidification  and  a  hygroscopic  condenser 
humidifier.  Chest  1993:104(6):I800-1805. 

55.  Martin  C.  Perrin  G.  Gevaudan  MJ,  Saux  P,  Gouin  F.  Heat  and 
moisture  exchangers  and  vaporizing  humidifiers  in  the  intensive  care 
unit.  Che.st  1990:97(1):  144-149. 

56.  Cohen  IL.  Weinberg  PF.  Fein  lA.  Rowiniski  GS.  Endotracheal  tube 
occlusion  associated  with  the  use  of  heat  moisture  exchangers  in  the 
intensive  care  unit.  Crit  Care  Med  l988;16(3):277-279. 

57.  Misset  B,  Escudier  B,  Rivara  D,  Leclercq  B,  Nitenberg  G.  Heat  and 
moisture  exchanger  vs  heated  humidifier  during  long-term  mechan- 
ical ventilation.  Chest  1991;1()()(1  ):16()-163. 

58.  Roustan  JP.  Kienlen  J,  Aubas  P,  Aubas  S,  du  Cailar  J.  Comparison 
of  hydrophobic  heat  and  moisture  exchanger  with  heated  humidifiers 
during  prolonged  mechanical  ventilation.  Intensive  Care  Med  1992; 
I8(2):97-100. 


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HUMIDIFICATION  FOR  PATIENTS  WITH  ARTIFICIAL  AlRWAYS 


59.  Suzukawa  M.  Usuda  Y.  Numata  K.  The  effects  on  sputum  charac- 
teristics of  combining  an  unheated  humidifier  with  a  hcal-moisture 
exchanging  filter.  Respir  Care  I989;34(l  I  ):976-984. 

60.  Beydon  L.  Tong  D,  Jackson  N.  Dreyfuss  D.  Correlation  between 
simple  clinical  parameters  and  the  in  vitro  humidification  character- 
istics of  filter  heat  and  moisture  exchangers.  Groupe  de  Travail  sur 
les  Respirateurs.  Che.st  1 997;  1 12(3  ):739-744. 

61.  Gallagher  I.  Strangeways  JE.  Allt-Graham  J.  Contamination  control 
in  long-term  ventilation.  A  clinical  study  using  a  heal-  and  moisture- 
exchanging  filter.  Anaesthesia  1987:42(5):476-481. 

62.  Djedaini  K.  Billiard  M.  Mier  L.  Bourdelles  G.  Brun  P.  Markowicz  P, 
et  al.  Changing  heat  and  moisture  exchangers  every  48  hours  rather 
than  24  hours  does  not  affect  their  efficacy  and  the  incidence  of 
nosocomial  pneumonia.  Am  J  Respir  Crit  Care  Med  1995;  152(5  Pt 
I):  1562- 1569. 

63.  Kollef  MH.  Shapiro  SD.  Boyd  V.  Silver  P.  Von  Harz  B,  Trovlllion 
E.  Prentice  D.  A  randomized  clinical  trial  comparing  an  extended- 
use  hygroscopic  condenser  humidifier  with  heated-water  humid- 
ification in  mechanically  ventilated  patients.  Chest  1998;1I3C3): 
759-767. 


64.  Davis  K  JR.  Evans  SL.  Campbell  RS.  Johannigman  JA.  Liichette  FA. 
Porembka  DT,  Branson  RD.  Prolonged  use  of  heat  and  moisture 
exchangers  does  not  effect  device  efficiency  or  Incidence  of  noso- 
comial pneumonia.  Crit  Care  Med  (1999,  in  press). 

65.  Branson  RD.  Davis  K  Jr.  Brown  R.  Rashkin  M.  Comparison  of  three 
humidltlcatlon  techniques  during  mechanical  ventilation:  Patient  se- 
lection, cost,  and  infection  considerations.  Respir  Care  I996;4I(9): 
809-816. 

Grolman  W.  Bloni  ED.  Branson  RD.  Schouwenburg  PF.  Hamaker 
RC.  An  efficiency  comparison  of  four  heat  and  moisture  exchangers 
used  in  the  laryngectoniized  patient.  Laryngoscope  I997;107(6):814- 
820. 

Hilgers  FJ.  Aaronson  NK.  Ackerstaff  AH.  Schouwenburg  PF.  van 
Zandwikj  N.  The  influence  of  a  heat  and  moisture  exchanger  (HME) 
on  the  respiratory  symptoms  after  total  laryngectomy.  Clin  Otolar- 
yngol 199I;16(2):I52-I56. 

68.  Ackerstaff  AH.  Hilgers  FJ.  Aaronson  NK.  Balm  AJ.  van  Zandwijk 
N.  Improvements  in  respiratory  and  psychosocial  functioning  fol- 
lowing total  laryngectomy  by  the  use  of  a  heat  and  moisture  ex- 
changer. Ann  Otol  Rhinol  Laryngol  I993;l()2(  1 1  ):878-883. 


66 


67 


Discussion 

Durbin:  I  would  like  to  expand  on 
your  comment  about  patients  with 
"thickening"  secretions  as  opposed  to 
"thick"  secretions.  I  assume  you  meant 
a  change  in  the  secretion  pattern.  You 
then  recommend  a  heated  wire  or  a 
more  efficient  heated  humidification. 
Intuitively,  I  think  that  makes  sense, 
but  I  don't  know  that  I've  ever  seen 
any  objective  documentation  of  clini- 
cal effectiveness.  Most  people  look  at 
indirect  measures  of  effectiveness  of 
humidification.  Most  report  clogging 
of  endotracheal  tubes  and  needing  to 
frequently  change  the  HME,  but  are 
there  any  data  that  indicate  that  with 
thickening  secretions  one  technique, 
or  a  higher  humidity  level,  is  better 
than  another? 

Branson:  I  didn't  show  the  algo- 
rithm, but  we  have  an  algorithm  that 
we  use.  It's  not  that  the  therapists  look 
at  it,  but  if  the  patient  comes  in  with 
known  thick  secretions  or  bloody  se- 
cretions, or  they're  hypothermic,  they 
use  the  heated  humidifier  from  the  first 
day  on  the  ventilator.  We  check  the 
secretions  over  a  period  of  days  (see 
our  studies  in  Chest^  and  in  Respira- 
tory Care"),  and  if  the  secretions  are 
thick  (as  defined  by  Suzukawa"*)  dur- 


ing 2  consecutive  suctioning  attempts, 
we  change  to  heated  humidification. 
That's  based  on  our  analysis  of  the 
data  in  the  studies  by  Cohen,^  Mar- 
tin,'' Misset,*^"  and  Roustan.^  These  all 
reported  incidences  of  occlusion  of  the 
endotracheal  tube,  and  the  majority  of 
problems  occurred  between  the  fifth 
and  the  seventh  day.  So,  for  any  pa- 
tient who  stays  on  for  longer  than  about 
5  days,  if  they  have  any  problems  with 
secretions,  we  switch  them  to  a  heated 
humidifier.  I  don't  know  the  answer, 
to  be  honest  with  you.  A  lot  of  people 
say,  "Put  an  HME  on  everybody,  and 
if  you  have  a  problem,  then  switch  to 
a  heated  humidifier."  I  don't  know  if 
that's  right  or  not. 


REFERENCES 


1.  Branson  RD.  Davis  K  Jr.  Campbell  RS. 
Johnson  DJ.  Porembka  DT.  Humidification 
in  the  intensive  care  unit.  Prospective  study 
of  a  new  protocol  utilizing  heated  humidi- 
fication and  a  hygroscopic  condenser  hu- 
midifier. Chest  1993;104(6):18(X)-1805. 

2.  Branson  RD,  Davis  K  Jr.  Brown  R.  Rash- 
kin  M.  Comparison  of  three  humidification 
techniques  during  mechanical  ventilation: 
patient  selection,  cost,  and  Infection  con- 
siderations. Respir  Care  1 996:4 1(9):809- 
816. 

3.  Suzukawa  M.  Usuda  Y.  Numata  K.  The 
effects  on  sputum  characteristics  of  com- 
bining an  unheated  humidifier  with  a  heat- 
moisture  exchanging  filter.  Respir  Care 
1989;.M(ll):976-984. 


4.  Cohen  IL.  Weinberg  PF.  Fein  lA,  Rowin- 
skl  GS.  Endotracheal  tube  occlusion  asso- 
ciated with  the  use  of  heat  and  moisture 
exchangers  in  the  intensive  care  unit.  Crit 
Care  Med  1988:l6(3):277-279. 

5.  Martin  C.  Perrin  G.  Gevaudan  MJ.  Saux  P. 
Gouin  F.  Heat  and  moisture  exchangers  and 
vaporizing  humidifiers  in  the  Intensive  care 
unit.  Chest  1990.97(  1):  144-149. 

6.  Misset  B.  Escudier  B.  RIvara  D,  l^clercq  B, 
Nitenberg  G.  Heat  and  moisture  exchanger 
vs  heated  humidifier  during  long-term  me- 
chanical ventilation.  A  prospective  random- 
ized study.  Chest  I991;1(X)(  1):160-163. 

7.  Roustan  JP,  Kienlen  J.  Aubas  P,  Aubas  S, 
du  Cailar  J.  Comparison  of  hydrophobic 
heat  and  moisture  exchangers  with  heated 
humidifier  during  prolonged  mechanical 
venti  lation.  Intensive  Care  Med  1 992;  1 8(2): 
97-100. 

Hess:  In  patients  whom  you  have 
changed  from  an  HME  to  an  active 
humidification  system  because  of 
thickened  secretions,  have  you  fol- 
lowed up  to  see  if  their  secretions 
change  after  they're  on  the  active  hu- 
midification? 

Branson:  We've  watched  some  of 
them.  Some  get  a  change  in  the  secre- 
tions, but  most  of  them  don't.  They 
generally  have  thickened  secretions 
because  they  have  a  process  going  on, 
such  as  pneumonia,  and  in  those  pa- 
tients, increasing  the  humidity  proba- 
bly doesn't  change  secretion  quality. 


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64; 


HUMIDIFICATION  FOR  PATIENTS  WITH  ARTIFICIAL  AlRWAYS 


But  I  really  have  the  feeling  that  if  you 
had  left  them  on  an  artificial  nose,  the 
secretions  would  have  dried  and  they 
would  start  to  get  encrustation  of  secre- 
tions inside  the  endotracheal  tube. 

Hess:     So,  we  really  don't  know. 

Branson:  We  don't  know.  But,  for 
me,  it's  just  safety.  It's  still  my  opin- 
ion that  if  an  artificial  nose  weren't 
cheaper,  nobody  would  have  ever  used 
one.  I'm  sure  all  those  of  you  who 
were  trying  to  get  people  to  use  them 
were  just  sure  they  couldn't  possibly 
work,  and  now  I'm  to  the  point  where 
I'm  concerned  because  people  think 
they're  going  to  use  them  on  every- 
body because  they're  so  much  cheaper. 
But  all  those  cost  savings  totally  dis- 
appear if  you  have  even  one  plugged 
endotracheal  tube  and  have  to  resus- 
citate even  one  patient. 

Ritz:  We've  been  wrestling  with  this 
issue  of  HMEs  on  all  patients — to  start 
them  off  that  way — and  the  really  com- 
plex problem  that  I'  m  not  sure  we  have 
the  solution  to  yet  is  what  to  do  about 
nebulized  drugs  or  MDIs.  If  you  want 
to  instill  medications  between  the 
HME  and  the  patient,  it  seems  like 
you'd  add  a  lot  of  cumbersome  appa- 
ratus between  the  HME  and  the  pa- 
tient. On  the  other  hand,  if  you  mount 
the  aerosol  delivery  system  away  from 
the  patient,  you  have  to  disconnect  the 
tube  and  remove  the  HME  to  adminis- 
ter the  medications.  Any  suggestions? 

Branson:  I  agree.  In  the  last  study 
that  we  did,  working  in  a  surgical  ICU, 
where  we  do  most  of  our  work,  we 
found  using  an  HME  very  easy  prob- 
ably two-thirds  of  the  time.  But  in  a 
medical  ICU,  we  found  we  could  use 
an  HME  only  about  a  quarter  of  the 
time.  One  of  the  reasons  for  not  using 
it  there  is  the  problem  you  brought  up. 
If  you're  going  to  use  an  MDI,  you 
usually  have  to  u.se  an  MDI  right  at 
the  end  of  the  endotracheal  tube,  or  if 
you're  going  to  use  an  MDI  farther 
down  with  a  spacer  or  you're  going  to 


use  an  updraft  nebulizer,  you  have  to 
remove  the  HME  every  time  you  do  a 
bronchodilator  treatment.  We  hardly 
do  any  bronchodilator  in  the  surgical 
ICU  (20-year-old  trauma  patients 
don't  tend  to  have  bronchospasm)  but 
in  a  medical  ICU,  almost  everybody 
is  on  frequent  bronchodilator  therapy. 
That  is  an  issue.  In  the  medical  ICU, 
we  find  we  use  HMEs  much  less  fre- 
quently than  the  surgical  ICU. 

Hess:  I  think  that  outside  the  United 
States  that's  not  necessarily  true.  It 
seems  to  me  that  the  use  of  active 
humidifiers  is  very  much  an  Ameri- 
can, New  Zealand,  or  Australian  kind 
of  phenomenon,  and  when  you  get  into 
Europe  and  Central  and  South  Amer- 
ica, my  sense  is  that  there  is  a  lot  more 
use  of  passive  humidifiers.  I  just  vis- 
ited an  ICU  in  Mexico  City,  and  they 
had  everybody  on  an  HME.  They  said 
they  have  not  used  an  active  humidi- 
fier in  years,  and  they  didn't  even  think 
they  had  one  anymore.  So,  the  sense 
that  I  have  is  that  we  could  probably 
use  a  lot  more  passive  humidification  in 
the  United  States,  but  because  of  our 
health  care  delivery  system,  or  what- 
ever, we've  not  adopted  that  practice. 

Branson:  I  agree.  I've  been  to  New 
Zealand  and  seen  John  Lawrence's 
group,  who  deliver  39°C  gas  to  the 
airway  at  100%  relative  humidity,  and 
could  never  imagine  doing  anything 
else.  And  Didier  Dreyfuss  told  me  he 
doesn't  own  a  heated  humidifier  either. 
But  I've  also  talked  to  John  Marini,  and 
he'd  never  use  a  passive  humidifier,  be- 
cause of  the  dead  space.  1  think  the  right 
answer  is  somewhere  in  the  middle,  and 
that's  the  principle  we  adopted.  Use  it 
on  everybody  for  whom  it's  appropri- 
ate; you'll  save  money,  and  it's  simpler 
and  less  complex. 

Durbin:  Can  1  ask  Jim  Reibel  to 
comment  on  airway  humidification  in 
patients  following  laryngectomy?  Is 
this  a  big  issue  or  a  concern  of  your 
specialty  (otorhinology)? 


Reibel:  In  the  United  States,  it' s  not. 
The  Europeans,  interestingly,  have 
been  very  active  in  promulgating  the 
use  of  a  passive  humidification  device 
for  laryngectomy  patients,  saying  that 
it  improves  their  pulmonary  function. 
It's  not  been  something  we've  adopted 
in  the  United  States,  I  think  mostly  be- 
cause of  issues  regarding  surgeon  pref- 
erence and  patient  compliance.  T  ve  tried 
a  lot  of  different  things  on  laryngec- 
tomy patients,  and  simple  is  better. 

Branson:  I  worked  with  a  group  in 
Indianapolis  who  make  a  speaking 
valve  for  laryngectomy  patients,  and 
one  of  their  goals  was  to  add  a  heat 
and  moisture  exchanging  filter  to  the 
outside.  We  published  a  paper  about  it 
in  Laryngoscope, '  and  one  of  the  phy- 
sicians who  was  doing  the  patient  side 
(we  just  did  the  evaluation  in  the  lab- 
oratory) found  that  the  patients  who 
used  this  device  with  adding  heat  and 
moisture  had  about  a  third  less  cough- 
ing episodes  per  day.  I  didn't  think  that 
could  be  a  very  big  deal  until  they  told 
me  that  the  average  patient  coughs  up 
into  a  4  X  4  about  30  times  a  day.  Well, 
if  you  only  cough  up  into  a  4  X  4  ten 
times  a  day,  I  would  think  that,  from  the 
patient's  standpoint,  that's  a  substantial 
improvement  in  quality  of  life. 

REFERENCE 

I .  Grolman  W,  Blom  ED,  Branson  RD,  Schou- 
wenburg  PF,  Hamaker  RC.  An  efficiency 
comparison  of  four  heat  and  moisture  ex- 
changers used  in  the  laryngectomized  pa- 
tient. Laryngoscope  1997;I07(6):814-820. 

Reibel:  The  down  side  to  that  in  the 
laryngectomy  patient,  though,  is  that, 
for  these  things  to  work,  they  have  to 
be  fixed  to  the  skin  with  adhesive.  If  a 
patient  coughs  forcefully  enough,  he 
will  dislodge  the  whole  thing  and  have 
to  go  through  the  laborious  process  of 
reapplication.  So,  most  of  the  folks 
who've  used  the  valve  you  mentioned 
for  their  speech  rehabilitation  cough  it 
off  a  few  times  and  throw  up  their 
hands  and  give  up  using  it. 


642 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Nasotracheal  Intubation 


William  E  Hurford  MD 


Indications  and  Advantages 
Contraindications  and  Disadvantages 
Techniques 

Risks  and  Complications 
Summary 

[Respir  Care  1999;44(6):643-647]  Key  words:  nasotracheal  intubation,  endo- 
tracheal intubation,  artificial  airways,  intubation  techniques,  airway  manage- 
ment, sinusitis,  airway  cmatomy. 


Indications  and  Advantages 

Nasotracheal  intubation  may  be  required  for  patients 
undergoing  an  intraoral  surgical  procedure  (Table  1).'  An 
intraoral  tube  may  interfere  with  surgical  exposure  during 
intraoral  procedures  and  have  an  increased  risk  of  dislodg- 
ment  during  surgery.  An  intraoral  tube  is  also  to  be  avoided 
if  postoperative  intraoral  maxillary  fixation  of  the  mandi- 
ble is  necessary.  Nasotracheal  intubation  should  also  be 
considered  when  the  oral  route  is  difficult  or  impossible 
(eg,  limited  mouth  opening  secondary  to  scar  contractures 
or  temporomandibular  joint  dysfunction).  Nasotracheal  in- 
tubation may  also  be  considered  in  situations  where  visu- 
alization by  direct  or  fiberoptic  laryngoscopy  is  poor  (eg, 
severe  oral  trauma  and  hemorrhage). 

Nasotracheal  intubation  offers  several  advantages  over 
the  oral  route  (Table  2).  Nasal  tubes  are  easily  secured  to 
the  bridge  of  the  nose,  and  the  nasal  passages  may  help 
keep  the  tube  in  place.  Nursing  care  of  the  mouth  is  sim- 
plified, communication  with  the  intubated  patient  is  easier 
since  the  lips  and  mouth  are  unencumbered  by  the  tube 
and  tape,  and  the  tube  cannot  be  occluded  by  an  uncoop- 
erative patient  who  may  bite  down  on  an  oral  tube.  Naso- 
tracheal intubation  can  be  accomplished  "blindly"  (ie,  with- 
out the  use  of  a  laryngoscope),  or  over  a  fiberoptic 
laryngoscope,  in  the  awake  patient.  In  the  past,  it  was 
believed  that  the  nasal  approach  to  endotracheal  intubation 


William  E  Hurford  MD  is  affiliated  with  the  Department  of  Anaesthesia 
and  Critical  Care.  Massachusetts  General  Hospital,  and  Harvard  Medical 
School.  Boston,  Massachusetts. 

Correspondence:  William  E  Hurford  MD.  Department  of  Anaesthesia 
and  Critical  Care.  Massachusetts  General  Hospital.  Boston  MA  021  14. 
E-mail:  hurford@etherdome.mgh.harvard.edu. 


caused  less  movement  of  the  cervical  spine  (critical  in 
patients  with  suspected  injuries  of  the  cervical  spine),  but 
this  advantage  has  not  been  substantiated  in  experimental 
or  clinical  studies.-  ■*  The  frequency  and  severity  of  laryn- 
geal injury  has  also  been  reported  to  be  reduced  following 
nasal  intubation  compared  to  oral  intubation.^  These  re- 
sults may  simply  be  due  to  the  smaller  tube  diameter  usu- 
ally used  for  nasotracheal  intubation. 

Contraindications  and  Disadvantages 

Relative  contraindications  to  nasotracheal  intubation  in- 
clude the  presence  of  a  basilar  skull  fracture  (especially  of 
the  ethmoid  bone),  nasal  fractures,  epistaxis,  nasal  polyps, 
coagulopathy,  or  planned  systemic  anticoagulation  or 
thrombolysis,  for  example,  in  the  patient  with  acute  myo- 
cardial infarction  (see  Table  1).  Nasal  intubation  also  is 
usually  more  time-consuming  than  the  oral  route. ''^  When 
time  is  of  the  essence,  as  in  a  cardiac  arrest,  the  nasal  route 
for  intubation  is  a  poor  first  choice. 

The  use  of  nasotracheal  intubation  in  the  presence  of 
basilar  skull  and  facial  fractures  is  somewhat  controver- 
sial. Nasotracheal  intubation  has  been  performed  in  se- 
lected patients  with  basilar  skull  fractures  without  appar- 
ent adverse  effects.**  In  a  retrospective  review  of  82  patients 
with  facial  fractures  who  were  nasotracheally  intubated  at 
the  Massachusetts  General  Hospital,  there  were  no  instances 
of  intracranial  placement,  epistaxis  requiring  nasal  pack- 
ing, or  esophageal  intubation.'^  Three  patients  developed 
sinusitis  and  8  developed  aspiration  pneumonia.  Another 
retrospective  analysis,  of  1 60  patients  with  frontobasal  frac- 
tures and  simultaneous  leak  of  cerebrospinal  fluid,  sug- 
gested that  the  route  of  endotracheal  intubation  used  for 
surgical  repair  did  not  appear  to  influence  the  occurrence 


Respiratory  Care  •  June  1999  Vol  44  No  6 


643 


Nasotracheal  Intubation 


Table  1. 


Indications  and  Contraindications  for  Nasotracheal 
Intubation 


Indications 


Contraindications 


Intraoral  surgery  Basilar  skull  fracture 

Poor  mouth  opening  Nasal  fractures 

Difficult  or  impossible  visualization  Epistaxis 

with  direct  and/or  fiberoptic  Nasal  polyps 

laryngoscopy  Coagulopathy 

Improvement  in  mouth  care  Planned  systemic  anticoagulation 
Improvement  in  communication  and/or  thrombolysis 

with  patient  Emergency  situation 
Improvement  in  stability  and 

avoidance  of  biting  on  an 

orotracheal  tube  in  uncooperative 

patients 


Table  2.      Advantages  and  Disadvantages  of  Nasotracheal  Intubation 


Advantages 


Disadvantages 


Permits  unobstructed  surgical  field  Smaller  diameter  endotracheal 

for  intraoral  surgery  tube 

Oral  cavity  left  free  of  tubes  Increased  risk  of  sinusitis 

Permit  intraoral  maxillary  fixation  Possibility  of  erosion  of  the  nasal 

of  mandibular  fractures  alae 

May  be  performed  "blindly"  (ie.  Increased  resistance  to  breathing 

without  direct  laryngoscopy)  Increased  risk  of  epistaxis 
Risk  of  dislodgment  may  be 

reduced  in  selected  patients 


of  postoperative  complications.'"  The  duration  of  such  in- 
tubations, however,  is  generally  brief,  and  prophylactic 
antibiotics  are  usually  administered. 

The  nasotracheal  route  has  several  practical  disadvan- 
tages (see  Table  2).  Compared  with  oral  endotracheal  tubes, 
the  inner  diameter  of  tubes  used  for  nasotracheal  intuba- 
tion is  usually  smaller  and  the  tube  slightly  longer.  These 
factors  may  increase  airway  resistance  and  work  of  breath- 
ing." The  tube  tends  to  soften  and  kink  in  the  nasophar- 
ynx, which  could  further  increase  airway  resistance  and 
makes  passage  of  a  suction  catheter  more  difficult.  Thus, 
clearance  of  secretions  could  be  more  problematic  with  a 
nasotracheal  tube.  The  nasotracheal  route  is  now  rarely 
used  for  long-term  intubation  because  of  concerns  of  in- 
creased work  of  breathing  and  increased  risk  of  sinusitis. 

Techniques 

Most  of  the  basic  techniques  for  nasotracheal  intubation 
are  similar  to  those  used  for  orotracheal  intubation.  Ana- 
tomic relationships,  positioning  of  the  patient,  sedation 
and  anesthesia,  oxygen  therapy,  the  use  of  direct  laryn- 
goscopy, and  confirmation  of  endotracheal  tube  placement 


are  identical  for  both  techniques,  and  are  discussed  else- 
where.'- Outside  the  operating  room,  nasotracheal  intuba- 
tion is  most  commonly  performed  after  topical  anesthesia, 
with  the  patient  awake  and  breathing  spontaneously.  Anes- 
thetize and  vasoconstrict  the  nasal  mucosa  with  a  solution 
of  0.25%  phenylephrine-3%  lidocaine,  or  2%  lidocalne 
with  1 :200,000  epinephrine,  using  cotton-tipped  pledgets. " 
A  solution  of  4%  cocaine  is  sometimes  used  for  topical 
anesthesia,  but  its  use  is  severely  restricted  because  of 
concerns  over  possible  illicit  diversion  of  the  drug.  In  any 
event,  the  use  of  a  vasoconstrictor  agent  is  critical  to  re- 
ducing mucosal  edema  and  the  chance  of  epistaxis  during 
intubation.  Even  during  general  anesthesia,  vasoconstric- 
tion with  a  topical  solution  such  as  oxymetazoline  (Afrin) 
is  advisable.  Both  nasal  passages  should  be  treated  in  case 
that  the  initial  attempt  at  nasotracheal  intubation  is  unsuc- 
cessful. If  severe  bleeding  occurs,  leave  the  tube  in  place 
to  help  tamponade  the  bleeding  site.  The  use  of  nasal 
packs  and  surgical  intervention  may  be  necessary  to  treat 
life-threatening  epistaxis.  Additional  topical  anesthesia  to 
the  airway  and  the  administration  of  intravenous  sedation 
may  be  desirable,  and  are  discussed  elsewhere. '^ 

Judge  the  patency  of  both  nasal  passages  and  assess  for 
deviation  of  the  nasal  septum.  A  nasal  airway  lubricated 
with  anesthetic  paste  or  jelly  can  be  used  to  evaluate  and 
dilate  the  chosen  nasal  passage.  If  both  nares  are  patent, 
the  right  naris  may  be  preferable  for  intubation,  because 
the  bevel  of  most  endotracheal  tubes,  when  introduced 
through  the  right  naris,  will  face  the  flat  nasal  septum, 
reducing  the  possibility  of  damage  to  the  turbinates.  The 
inferior  turbinates  interfere  with  passage  and  limit  the  size 
of  the  endotracheal  tube.  Common  endotracheal  tube  sizes 
are:  6.0-6.5  mm  endotracheal  tube  for  women;  and  7.0- 
7.5  mm  endotracheal  tube  for  men.  Insertion  to  a  depth 
(measured  at  the  naris)  of  26  cm  in  women,  and  28  cm  in 
men,  has  been  reported  to  result  in  proper  tracheal  position 
in  over  95%  of  adult  patients.''' 

Advance  the  tube  perpendicular  to  the  face  and  parallel 
to  the  hard  palate.  Inexperienced  operators  tend  to  direct 
the  tube  cephalad,  which  tends  to  damage  the  turbinates. 
As  the  tube  is  passed  into  the  nasopharynx,  it  may  impact 
against  the  posterior  nasopharyngeal  wall.  Retract  the  tube 
slightly,  extend  the  patient's  neck,  and  re-advance.  Forc- 
ible advancement  of  the  tube  at  this  point  risks  tearing  the 
mucosa  and  creating  a  false  passage.  After  passage  through 
the  naris  into  the  pharynx,  advance  the  tube  through  the 
glottic  opening.  In  the  spontaneously  ventilating  patient, 
air  movement  detected  within  the  tube  can  be  used  to  help 
guide  insertion.'"^  Advance  the  tube  gently  during  inspira- 
tion (when  the  glottis  is  open).  Direct  the  tube  toward  the 
location  of  the  loudest  breath  sounds.  If  the  breath  sounds 
are  lost,  retract  the  tube,  redirect,  and  then  re-advance. 

If  intubation  is  difficult,  the  tip  of  the  endotracheal  tube 
may  have  been  directed  off  the  midline  and  into  a  pyriform 


644 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Nasotracheal  Intubation 


Fig.  1.  Effect  of  cervical  flexion  and  extension.  A:  In  the  neutral 
position,  the  tip  of  the  endotracheal  tube  lies  just  posterior  to  the 
epiglottis.  B:  Cervical  flexion  aligns  the  axis  of  the  tube  with  the 
axis  of  the  esophagus.  C:  Cervical  extension  aligns  the  axis  of 
the  tube  with  the  opening  of  the  larynx,  thus  bringing  the  tip  of  the 
tube  more  anteriorly.  (From  Reference  1 ,  with  permission.) 


Fig.  2.  Tilting  and  rotating  the  head  with  respect  to  the  torso.  A:  In 
the  neutral  position,  the  axis  of  the  nasotracheal  tube  parallels  the 
axis  of  the  trachea,  offset  toward  the  side  of  the  tube  insertion  (in 
this  case,  the  left  side).  B:  Rotation  of  the  head  aligns  the  axis  of 
the  tube  with  the  soft  tissue,  rather  than  with  the  entrance  of  the 
larynx.  C:  Tilting  the  head  to  the  side  of  the  insertion  (in  this  ex- 
ample, the  left)  guides  the  axis  of  the  tube  toward  the  axis  of  the 
trachea,  making  passage  into  the  trachea  more  likely.  D:  Tilting  the 
head  toward  the  opposite  side  guides  the  tube  toward  the  pyri- 
form  recess,  lateral  to  the  opening  of  the  larynx.  (From  Reference 
1 ,  with  permission.) 


recess,  anteriorly  into  the  vallecula,  or  posteriorly  into  the 
esophagus.'  Most  commonly,  the  tube  tends  to  enter  the 
esophagus.  Extending  the  patient's  neck  (Fig.  1)  or  pro- 
viding cricoid  pressure  tends  to  align  the  tube  with  the 
glottis  and  may  increase  the  chance  of  success.  Special 
endotracheal  tubes  are  available  that  have  a  cord  running 
up  the  concave  side  to  the  tip  of  the  tube  (Endotrol, 
Mallinckrodt  Inc,  Pleasanton,  California).  Pulling  on  a  ring 
attached  to  the  proximal  end  of  the  cord  flexes  the  tube 
anteriorly,  which  may  be  helpful.  Nasally  placed  tubes 
also  tend  to  be  directed  laterally  toward  the  side  of  the 
nares  used  for  insertion  (Fig.  2).  To  correct  this,  rotate  the 
tube  toward  the  midline.  Tilting  (not  rotating)  the  patient's 
head  toward  the  side  of  the  intubation  may  also  be  helpful. 
Passage  of  the  tube  under  direct  vision  using  laryngos- 
copy and  assisted  by  Magill  forceps  may  be  required.  Per- 
form direct  laryngoscopy  as  you  would  for  an  orotracheal 
intubation.  Magill  forceps  may  be  used  to  direct  the  tip  of 
the  endotracheal  tube  anteriorly  and  through  the  glottis 
(Fig.  3).  Grasp  the  tube  with  the  forceps  proximal  to  the 


Fig.  3.  Nasotracheal  intubation  with  Magill  forceps.  The  forceps 
direct  the  end  of  the  tube  through  the  vocal  cords.  The  tube  is 
grasped,  not  by  the  tip  or  the  endotracheal  tube  cuff,  but  more 
proximally.  (From  Reference  35,  with  permission.) 


endotracheal  tube  cuff.  This  reduces  the  chance  of  dam- 
aging the  endotracheal  tube  cuff  during  insertion  and  per- 
mits the  distal  end  of  the  tube  to  be  inserted  through  the 
glottic  opening.  Have  an  assistant  advance  the  tube  as  you 
direct  it  with  the  forceps. 

A  fiberoptic  laryngoscope  can  also  be  used  to  assist 
nasotracheal  intubation."'  Considerations  for  nasotracheal 
fiberoptic  laryngoscopy  are  similar  to  the  oral  route  and 
are  discussed  elsewhere.'-  For  nasal  insertion,  the  inser- 
tion tube  of  the  fiberoptic  scope  is  initially  inserted  into 
the  nasal  passage  and  guided  into  the  trachea  under  direct 
vision.  A  properly  sized  endotracheal  tube  is  then  advanced 
into  the  trachea,  using  the  fiberoptic  scope  as  a  stylet. 
Avoidance  of  epistaxis  is  paramount  for  a  successful  fi- 
beroptic nasotracheal  intubation,  because  the  slightest 
bleeding  can  cover  the  lens  of  the  fiberoptic  bundle  and 
obscure  the  view. 

Risks  and  Complications 

Nasotracheal  intubation  shares  the  general  complica- 
tions that  can  occur  with  any  route  of  intubation.  In  addi- 
tion, complications  specific  to  nasotracheal  intubation  may 
also  occur  (Table  3). 

General  complications  of  endotracheal  intubation  include 
difficulty  with  intubation,  esophageal  or  endobronchial  in- 
tubation, and  trauma  to  the  pharynx,  larynx,  trachea,  and 


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Nasotracheal  Intubation 


Table  3.      Complications  of  Nasotracheal  Intubation 


General  Complications 


Specific  Complications 


Esophageal  intubation 
Endobronchial  intubation 
Trauma  to  the  pharynx,  larynx, 
trachea,  and  esophagus 


Epistaxis 

Bacteremia 

Damage  to  the  nasal  mucosa  and 

turbinates 
Creation  of  a  false  passage 
Retropharyngeal  placement 
Intracranial  placement 
Increased  risk  of  meningitis  in  the 

presence  of  rhinorrhea  of 

cerebrospinal  fluid 
Necrosis  of  the  nostril 
Ulceration  of  the  inferior  turbinate 
Sinusitis  and  otitis 


esophagus.  If  direct  laryngoscopy  is  performed,  trauma 
to  the  lips,  teeth,  gingiva,  tongue,  uvula,  and  tonsils  is 
possible. 

Complications  specific  to  nasotracheal  intubation  include 
nasal  hemorrhage,^  damage  to  the  nasal  mucosa  and  tur- 
binates,'^ submucosal  dissection  with  the  creation  of  a 
false  retropharyngeal  passage,  dislodgment  of  enlarged  ton- 
sils and  adenoids,  and  a  relatively  high  incidence  of  bac- 
teremia during  insertion. '  The  incidence  of  bacteremia  dur- 
ing nasotracheal  intubation  has  been  reported  to  range 
between  5.5%  and  17%,  and  generally  originates  from 
flora  colonizing  the  upper  airway.'-'''*'''^  Antibiotic  pro- 
phylaxis should  be  considered  prior  to  nasotracheal  intu- 
bation of  patients  at  increased  risk  for  bacterial  endocar- 
ditis. The  risk  of  meningitis  may  be  increased  when 
nasotracheal  intubation  is  performed  in  the  presence  of  a 
basilar  skull  fracture  and  rhinorrhea  of  cerebrospinal  fluid. 
Intracranial  placement  of  a  nasotracheal  tube  has  been 
described  in  the  presence  of  facial  fractures-"  and  during 
routine  nasotracheal  intubation  of  a  premature  infant.-' 

Long-term  complications  include  obstruction  of  maxil- 
lary sinus  drainage  caused  by  the  presence  of  the  tube  and 
resulting  edema  of  the  nasal  mucosa  (Fig.  4).----^  The  ob- 
structed sinus  becomes  easily  infected  in  the  critically  ill 
patient,  and  infection  can  spread  systemically  via  venous 
drainage  into  the  dural  venous  sinuses.-'*--'*  In  a  prospec- 
tive study  by  Rouby  et  al,  nasal  placement  and  duration  of 
intubation  were  significant  risk  factors  for  the  occurrence 
of  sinusitis.-''  An  increased  risk  of  sinusitis  during  naso- 
tracheal intubation  was  not  observed  in  a  study  by  Holz- 
apfel  et  al,  who  prospectively  followed  300  critically  ill 
patients  randomized  to  nasotracheal  or  orotracheal  intuba- 
tion.-" However,  their  study  design  may  have  obscured 
differences  due  to  the  route  of  intubation  because  it  did  not 
control  for  the  incidence  of  preexisting  sinusitis,  as  did  the 
study  by  Rouby  et  al. -''■-" 


Fig.  4.  Computed  tomography  scan  illustrating  sinusitis.  Left:  The 
head  computed  tomography  scan  of  a  motor  vehicle  accident 
victim  shows  clear  maxillary  sinuses  on  both  sides.  Right:  After  9 
days  of  nasal  endotracheal  intubation  and  nasogastric  tube  place- 
ment, the  patient  developed  sinusitis  as  evidenced  by  opacifica- 
tion and  air/fluid  levels  in  both  maxillary  sinuses.  (From  Reference 
1,  v\/ith  permission.) 


Signs  and  symptoms  of  sinusitis  are  often  obscured  in 
the  critically  ill  patient.^^  Only  about  30%  of  patients  with 
sinusitis  will  have  a  purulent  nasal  discharge.  Opacifica- 
tion of  the  sinuses  or  the  presence  of  an  air-fluid  level  and 
sinus  mucosal  thickening  seen  on  computed  tomography 
or  sinus  radiographs  can  be  used  to  confirm  the  diagnosis. 
Diagnosis  can  also  be  made  by  sterile  puncture  and  aspi- 
ration of  the  sinus  and  Gram-stain  and  culture  of  the  as- 
pirated fluid. 

Removing  nasotracheal  or  nasogastric  tubes,  elevating 
the  head  of  the  bed  so  that  dependent  drainage  can  occur, 
and  applying  topical  vasoconstrictors  and  saline  nasal 
sprays  are  effective  conservative  treatments  for  sinusitis. 
Antibiotics  may  be  administered  according  to  the  results 
of  Gram-stain  and  culture  of  nasal  drainage  or  sinus  aspi- 
rates. If  left  untreated,  bacteremia  may  occur  as  a  result  of 
the  sinusitis,  and  can  be  life-threatening.  '**-*-^"  Fortunately, 
surgical  drainage  is  rarely  necessary. ""■'- 

Short-term  nasotracheal  intubation  for  surgical  proce- 
dures is  usually  well  tolerated  and  causes  minimal  nasal 
damage.'-''  With  long-term  placement,  however,  ischemic 
necrosis  of  the  intubated  nostril  and  ulceration  of  the  in- 
ferior turbinate  can  occur.  Chronic  epistaxis  and  disfigure- 
ment can  result.  In  a  prospective  study  of  379  nasotrache- 
ally  intubated  patients  in  an  intensive  care  unit,  Holdgaard 
and  co-workers  reported  that  20%  had  ulcerations  of  the 
nostrils  and  29%  of  the  patients  had  ulcerations  of  the 
nasal  septum  at  some  time  during  intubation  or  up  to  5 
days  following  extubation.'-*  Epistaxis  occurred  in  19%, 
and  fractures  of  the  conchae  in  1 1%.  Among  the  281  pa- 
tients available  for  follow-up  1-2  years  later,  35%  com- 
plained of  symptoms  related  to  the  nose  and  nasal  cavity, 
24%  had  symptoms  relating  to  the  ears,  and  20%  had 
symptoms  relating  to  the  maxillary  sinus.  Increased  dura- 


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Nasotracheal  Intubation 


tion  of  intubation  was  correlated  with  the  occurrence  of 
ulcerations  and  the  persistence  of  symptoms.  The  study 
had  no  control  group,  however,  and  did  not  compare  the 
prevalence  of  symptoms  with  patients  receiving  orotra- 
cheal intubation  or  tracheostomy. 

Summary 

Perhaps  because  of  increased  concern  over  the  compli- 
cations of  nasotracheal  intubation,  and  the  ready  availabil- 
ity of  fiberoptic  laryngoscopy  to  assist  intubation,  the  use 
of  nasotracheal  intubation  has  declined  in  recent  years. 
Nevertheless,  nasotracheal  intubation  remains  an  impor- 
tant component  of  airway  management,  and  provides  a 
secure  airway  in  specific  situations,  most  commonly  dur- 
ing intraoral  surgery  or  after  trauma.  In  patients  whose 
mouth  opening  is  severely  limited,  the  nasotracheal  route 
may  be  the  only  path  that  avoids  a  surgical  airway. 


REFERENCES 


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2.  Hauswald  M,  Sklar  DP,  Tandberg  D,  Garcia  JF.  Cervical  spine  move- 
ment during  airway  management:  cinefluoroscopic  appraisal  in  hu- 
man cadavers.  Am  J  Emerg  Med  1991;9(6):.S35-.'i38. 

3.  Holley  J,  Jorden  R.  Airway  management  in  patients  with  unstable 
cervical  spine  fractures.  Ann  Emerg  Med  1989:18(1 1):  1237- 1239. 

4.  Suderman  VS.  Crosby  ET,  Lui  A.  Elective  oral  tracheal  intubation  in 
cervical  spine-injured  adults.  Can  J  Anaesth  1991:38(6):785-789. 

5.  Dubick  MN,  Wright  BD.  Comparison  of  laryngeal  pathology  fol- 
lowing long-term  oral  and  nasal  endotracheal  intubations.  Anesth 
Analg  1978;57(6):66.3-668. 

6.  Depoix  JP,  Malbezin  S,  Videcoq  M,  Hazebroucq  J,  Barbier-Bohm  G, 
Gauzit  R,  Desmonts  JM.  Oral  intubation  v.  nasal  intubation  in  adult 
cardiac  surgery.  Br  J  Anaesth  1987:59(2):  167-169. 

7.  Smith  JE,  Grewal  MS.  Cardiovascular  effects  of  nasotracheal  intu- 
bation. Anaesthesia  199l:46(8):683-686. 

8.  Arrowsmith  JE.  Robertshaw  HJ,  Boyd  JD.  Nasotracheal  intubation 
in  the  presence  of  frontobasal  skull  fracture.  Can  J  Anaesth  1998: 
45(1  ):7 1-75. 

9.  Rosen  CL,  Wolfe  RE,  Chew  SE.  Branney  SW,  Roe  EJ.  Blind  naso- 
tracheal intubation  in  the  presence  of  facial  trauma.  J  Emerg  Med 
1997;15(2):141-145. 

10.  Bahr  W,  Stoll  P.  Nasal  intubation  in  the  presence  of  frontobasal 
fractures:  a  retrospective  study.  J  Oral  Maxillofac  Surg  1992:50(5): 
445-447. 

Bolder  PM.  Healy  TE.  Bolder  AR.  Beatty  PC.  Kay  B.  The  extra 
work  of  breathing  through  adult  endotracheal  tubes.  Anesth  Analg 
1986;65(8):853-859. 

12.  Hurford  WE.  Orotracheal  intubation  outside  the  operating  room: 
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626. 

13.  Gross  JB,  Hartigan  ML,  Schaffer  DW.  A  suitable  sub.stitute  for  4% 
cocaine  before  blind  nasotracheal  intubation:  3%  lidocaine-0.259'c 
phenylephrine  nasal  spray.  Anesth  Analg  1984:63(10):915-918. 


II 


14.  Reed  DB,  Clinton  JE.  Proper  depth  of  placement  of  nasotracheal 
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15.  Harris  RD.  Gillett  MJ.  Joseph  AP,  Vinen  JD.  An  aid  to  blind  na.sal 
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16.  Ovassapian  A,  Randel  GI.  The  role  of  the  fiberscope  in  the  critically 
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17.  Dost  P,  Armbruster  W.  Nasal  turbinate  dislocation  caused  by  naso- 
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18.  Berry  FA  Jr.  Blankenbaker  WL,  Ball  CG.  Comparison  of  bacteremia 
occurring  with  nasotracheal  and  orotracheal  intubation.  Anesth  Analg 
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19.  Dinner  M,  Tjeuw  M,  Artusio  JF  Jr.  Bacteremia  as  a  complication  of 
nasotracheal  intubation.  Anesth  Analg  1 987:66(5  ):460-462. 

20.  Marlow  TJ,  Goltra  DD  Jr.  Schabel  SI.  Intracranial  placement  of  a 
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Med  1997:I5(2):187-19I, 

21.  Cameron  D,  Lupton  BA.  Inadvertent  brain  penetration  during  neo- 
natal nasotracheal  intubation.  Arch  Dis  Child  1993:69(1  Spec  No): 
79-80. 

22.  Michel.son  A,  Schuster  B,  Kamp  HD.  Parana.sal  sinusitis  associated 
with  nasotracheal  and  orotracheal  long-term  intubation.  Arch  Oto- 
laryngol Head  Neck  Surg  1992:1 18(9):937-939. 

23.  Rouby  JJ.  Laurent  P,  Gosnach  M,  Cambau  E,  Lamas  G,  Zouaoui  A, 
et  al.  Risk  factors  and  clinical  relevance  of  nosocomial  maxillary 
sinusitis  in  the  critically  ill.  Am  J  Respir  Crit  Care  Med  1994:150(3): 
776-783. 

24.  Caplan  E,  Hoyt  NJ.  Nosocomial  sinusitis.  JAMA  1982:247(5):639- 
641. 

25.  Deutschman  CS.  Wilton  PB.  Sinow  J,  Thienprasit  P,  Konstantinides 
FN,  Cerra  FB.  Paranasal  sinusitis:  a  common  complication  of  naso- 
tracheal intubation  in  neurosurgical  patients.  Neurosurgery  1985; 
17(2):296-299. 

26.  Holzapfel  L,  Chevret  S,  Madinier  G,  Ohen  F,  Demingeon  G,  Coupry 
A,  Chaudet  M.  Influence  of  long-term  oro-  or  na.sotracheal  intuba- 
tion on  nosocomial  maxillary  sinusitis  and  pneumonia:  results  of  a 
prospective,  randomized  clinical  trial.  Crit  Care  Med  1993:21(8): 
1132-1138. 

27.  Dellinger  RP.  Airway  management  and  nosocomial  infection  (edi- 
torial). Crit  Care  Med  1993:21(8):!  109-1 1 10. 

28.  Heffner  JE.  Nosocomial  sinusitis.  Den  of  multiresistant  thieves?  (ed- 
itorial) Am  J  Respir  Crit  Care  Med  1994;150(3):608-609. 

29.  Seiden  AM.  Sinusitis  in  the  critical  care  patient.  New  Horiz  1993; 
l(2):261-270. 

30.  Deutschman  CS.  Wilton  P.  Sinow  J.  Dibbell  D  Jr.  Konstantinides 
FN,  Cerra  FB.  Paranasal  sinusitis  associated  with  nasotracheal  intu- 
bation: a  frequently  unrecognized  and  treatable  source  of  sepsis.  Crit 
Care  Med  1986:14(2):1 1 1-1 14. 

3 1 .  Bowers  BL,  Purdue  GF,  Hunt  JL.  Paranasal  sinusitis  in  burn  patients 
following  nasotracheal  intubation.  Arch  Surg  I991;126(l  1):I41 1- 
1412. 

32.  Borman  KR.  Brown  PM.  Mezera  KK,  Jhaveri  H.  Occult  fever  in 
surgical  intensive  care  unit  patients  is  seldom  cau.sed  by  sinusitis. 
Am  J  Surg  1992:164(5):412-H6. 

33.  O'Connell  JE,  Stevenson  DS.  Stokes  MA.  Pathological  changes  as- 
sociated with  short-term  nasal  intubation.  Anaesthesia  1996:51(4): 
347-350. 

.34.  Holdgaard  HO,  Pedersen  J,  Schurizek  BA,  Melsen  NC,  Juhl  B.  Com- 
plications and  late  sequelae  following  nasotracheal  intubation.  Acta 
Anaesthesiol  Scand  1993;37(5):475^80. 

35.  Caroline  NL.  The  airway.  In:  Caroline  N,  editor.  Emergency  care  in 
the  streets.  Boston:  Little,  Brown  and  Company:  1994:63-1 12. 


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Discussion 

Stauffer:  Some  reports  have  sug- 
gested that  posterior  glottic  ulceration 
is  less  common  with  prolonged  nasal 
intubation  than  with  oral  intubation.'" 
My  thought  about  these  reports  was 
that  the  nasal  structures  anchored  the 
tube  better,  thereby  reducing  the  me- 
chanical forces  applied  to  the  glottis. 
Would  you  comment  on  this? 

REFERENCES 

1.  Stauffer  JL,  Olson  DE,  Petty  TL.  Compli- 
cations and  consequences  of  endotracheal 
intubation  and  tracheotomy:  a  prospective 
study  of  150  critically  ill  adult  patients. 
Am  J  Med  1981;70(l):65-76. 

2,  Dubick  MN,  Wright  BD.  Comparison  of 
laryngeal  pathology  following  long-term 
oral  and  nasal  endotracheal  intubations. 
Anesth  Analg  l978;57(6):663-668. 

Hurford:  The  reason  I  didn't  men- 
tion that  was  that  those  studies  did 
not,  to  my  knowledge,  control  for  the 
size  of  the  endotracheal  tube.  When 
you  control  for  the  size  of  the  tube, 
the  nasal  tubes  had  a  smaller  endotra- 
cheal tube  size  than  the  oral  tubes, 
and  those  differences  basically  become 
inconsequential.  So,  you  could  get  the 
same  advantage  by  using  a  smaller  oral 
tube.  I  think  those  advantages  were 
real — they  were  there.  So,  one  couldn't 
differentiate  between  an  effect  of  the 
tube  size  and  effect  of  the  route.  So  in 
that  absence,  1  dropped  that. 

Durbin:  A  couple  of  comments. 
First,  you  didn't  mention  inflation  of 
the  cuff  in  the  oropharynx  to  direct 
the  tube  tip  anterior.  That's  a  tech- 
nique that's  been  described  by  British 
anesthetists  for  a  number  of  years.  I 
recently  ran  across  a  couple  of  de- 
scriptions of  it.  Do  you  have  personal 
experience  inflating  the  cuff  in  the 
pharynx,  and  do  you  think  it  ought  to 
be  part  of  the  armamentarium?  Before 
you  answer  that,  let  me  also  say  that  if 
we  don't  do  more  nasal  intubations, 
nobody's  going  to  be  very  good  at 
them.  Most  anesthesia  residents  now 
are  poor  at  nase)tracheal  intubation,  be- 


cause they  do  so  few.  The  techniques 
you  described  are  very  reasonable. 
There  are  a  few  other  tricks  that  have 
been  developed  over  the  years:  for  ex- 
ample, listening  to  breath  sounds,  and 
when  to  advance  the  tube.  If  you  don't 
do  20  or  30  intubations,  you're  not 
ever  going  to  be  very  good.  If  we  don't 
teach  this  to  intubators,  the  next  gen- 
eration won't  ever  use  blind  nasal  in- 
tubation. Maybe  the  fiberoptic  ap- 
proach is  the  right  answer  for  most 
cases,  but  the  equipment  is  not  always 
available.  Should  we  even  bother  with 
nasotracheal  blind  intubations?  Should 
we  worry  about  not  teaching  this  to 
students?  Are  there  other  tricks  be- 
sides inflating  the  cuff  to  direct  the 
tube  tip  anterior  that  we  should  in- 
clude in  teaching  the  technique? 

Hurford:  I  think  certainly  it  should 
be  part  of  our  armamentarium,  and 
there  are  very  strong  indications  for 
nasal  intubations.  The  way  that  we 
keep  current  is  in  the  oral  surgery  clinic 
where  patients  receive  nasal  intuba- 
tions for  removal  of  impacted  wisdom 
teeth  under  general  anesthesia.  With 
ear,  nose,  and  throat  practice  and  oral 
surgery  procedures,  you  can  remain 
quite  skilled  in  nasal  intubation  and 
use  a  whole  variety  of  techniques.  Cer- 
tainly, there  are  a  number  of  techniques 
that  either  help  you  localize  where  you 
are  in  the  airway,  or  help  the  endotra- 
cheal tube  move  anteriorly  when  it  is 
aiming  toward  the  esophagus.  The 
techniques  that  help  you  know  where 
you  are  include  listening  over  the  tube, 
advancing  during  inhalation,  and  lis- 
tening to  exhalation.  One  can  use  de- 
vices on  the  tubes,  such  as  whistles 
that  make  the  airflow  sound  louder, 
which  is  especially  important  in  a  noisy 
environment.  Light  wands  and  lighted 
stylets  have  also  been  used  so  you  can 
also  see  where  the  tube  is  going.  And, 
of  course,  fiberoptic-assisted  intuba- 
tion can  be  used  as  well.  The  second 
group  of  techniques  are  for  making 
the  tube  move  anteriorly,  and  include 
the  balloon  inflation  technique.  In  my 
experience  the  tube  gets  partially  in 


the  glottis,  you  deflate  the  balloon,  and 
it  flops  back  posteriorly.  The  Endotrol 
tube  (Mallinckrodt  Inc,  Pleasanton, 
California),  has  a  ring  that  can  be 
pulled  to  flex  the  tip  of  the  tube  and 
thereby  assist  in  targeting  the  glottis. 
There  are  also  a  variety  of  flexible 
nasal-route  stylets,  for  lack  of  a  better 
term,  that  I'm  not  as  familiar  with. 
And  lastly,  for  completeness,  there  are 
retrograde  techniques,  where  wires 
and  guide  wires  are  passed  back  up 
through  the  oropharynx  and  then 
fished  out  of  the  nose  and  then  back 
through. 

Bisliop:  I  agree  totally  with  Charlie 
(Durbin)  that  unless  you  do  these  a 
fair  bit,  it  seems  like  a  difficult  tech- 
nique. However,  those  of  us  who 
trained  before  fiberoptic  scopes  were 
routinely  available  for  intubation  got 
a  lot  of  experience.  In  fact,  in  the  dys- 
pneic  patient  you  can  often  just  throw 
it  in,  practically  from  across  the 
room — they  just  suck  it  in.  So,  I  think 
it's  not  all  that  difficult  a  technique 
once  you  get  some  experience  with  it. 
But  that  wasn't  the  reason  I  raised  my 
hand.  I  have  a  couple  of  comments. 
One  is,  are  you  suggesting  that  the  re- 
sistance to  breathing  through  a  nasal  tube 
of  comparable  size  is  different? 

Hurford:  No,  because  the  tubes  are 
generally  smaller  and  generally  longer, 
as  Dean  Hess  reviewed  in  his  talk,  the 
resistance  tends  to  be  higher.  But, 
given  the  same  tube,  there  is  no  dif- 
ference in  resistance.' 

REFERENCE 

1.  Kil  HK.  Bishop  MJ.  Head  position  and 
oral  vs  nasal  route  as  factors  determining 
endotracheal  tube  resistance.  Chest  1994; 
10.'i(6):1794-1797. 

Bishop:  1  have  concerns  about  the 
Rouby  study.'  It  seems  to  be  a  very 
nice  study.  I've  never  really  been  able 
to  find  anything  wrong  with  it.  On  the 
other  hand,  I  don't  think  that  it  goes 
along  with  the  experience  of  the  ina- 
jority  of  people  in  the  world.  I  know 


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Nasotracheal  Intubation 


of  a  study  at  Harborview,  which  was 
never  published,  in  which  an  otolar- 
yngologist routinely  checked  for  si- 
nus fluid  in  a  fairly  large  number  of 
nasally  intubated  patients.  If  the  pa- 
tients had  maxillary  sinus  fluid,  he 
tapped  it.  and.  for  the  most  part,  the 
fluid  was  not  pus.  The  only  patients 
who  had  pus  also  had  active  drainage. 
So.  that  study  suggests  that  unless  you 
actually  see  some  drainage,  clinically 
significant  sinusitis  is  not  present.  I 
asked  the  folks  in  Paris  whether  the 
Rouby  study  changed  their  practice, 
and  they  said  that  now  they  worry 
about  it  more,  but  that  they  still  use 
nasal  intubation.  I"  m  not  sure  that  Rou- 
by's  work  is  consistent  with  the  expe- 
rience of  a  lot  of  other  intensive  care 
units — that  the  incidence  of  sinusitis 
is  quite  as  high  as  he  had  in  his  paper. 
I'd  like  to  hear  from  other  people  here 
about  that. 

REFERENCE 

1 .  Rouby  JJ.  Laurent  P.  Gosnach  M.  Cambau 
E.  Lamas  G.  Zouaoui  A.  et  al.  Risk  factors 
and  clinical  relevance  of  nosocomial  max- 
illary sinusitis  in  the  critically  ill.  Am  J 
Respir  Crit  Care  Med  1994;1.^0{3):776- 
783, 

Reibel:  In  the  difficult  airway  I  have 
a  problem  with  maintenance  of  a  na- 
sotracheal tube  in  somebody  who  can't 
open  their  mouth,  and  maybe  a  diffi- 
cult reintubation  if  you're  not  there. 
Those  people  we  would  have  no  prob- 
lem with  maintaining  the  airway  dur- 
ing their  surgery,  whether  it  be  or- 
thognathic surgery,  or  a  head/neck 
operation,  but  we  trach  all  those  peo- 
ple for  safety.  We  know  that  they're 
going  to  have  swelling,  and  if  we  don't 
have  an  attending  with  significant  ex- 
perience to  reestablish  that  airway 
quickly,  then  a  patient  who  should 


have  an  easy  postoperative  convales- 
cence may  die. 

Hurford:  I  think  that's  a  reasonable 
approach.  For  the  patient  with  poor 
mouth  opening,  we  tend  to  rely  on  the 
nasal  route  for  very  short-term  intu- 
bation. Doing  so  where  the  facilities 
to  perform  a  tracheostomy  subse- 
quently, or  to  assure  the  airway  will 
stay  in  the  correct  place  is  one  thing, 
but  if  you're  going  home  at  night,  I 
will  agree  with  you.  I  would  much 
prefer  going  home  with  the  patient  tra- 
cheostomized. 

Reibel:  It's  not  uncommon  for  us  to 
have  a  patient  who's  been  fully  irra- 
diated that  Charlie  and  the  residents 
will  spend  a  lot  of  time  nasally  intu- 
bating. Our  residents  will  say,  "Why 
didn't  we  just  trach  him  under  a  lo- 
cal?" For  complex  head/neck  resec- 
tions with  free  tissue  reconstruction, 
having  an  armored  tube  or  trach  tube 
in  the  way  as  you  are  getting  the  mi- 
croscope in  and  trying  to  get  the  ves- 
sels and  flap  inset  is  an  obstacle.  The 
nasotracheal  tube  can  really  expedite 
and  facilitate  the  accomplishment  of 
the  surgery.  But  after  flap  inset,  we 
switch  to  a  trach  at  the  end  for  safety. 

Hurford:  I'd  like  to  go  back  to  Mike 
Bishop's  comment  for  a  second,  be- 
cause certainly  what  Rouby  described 
regarding  the  incidence  of  sinusitis  is, 
I  think,  relatively  consistent  with  what 
other  people  have  seen  if  you  use  a 
very  generous  definition  of  sinusitis. 
Then.  I  think  our  second  experience  is 
that  if  you  notice  it.  or  if  you  miss  it, 
in  most  people,  it's  no  big  deal.  You 
take  out  the  nasal  tube  if  it's  present. 
You  give  local  vasoconstrictors,  ele- 
vate the  head,  some  saline  sprays. 


maybe  antibiotics  if  you  have  infected 
drainage  or  aspirants.  But,  in  general, 
the  vast  majority  of  these  folks  do  fine, 
don't  get  into  any  problems,  and  it's 
basically  silent.  I  think  they  made  a 
big  effort  to  look  hard  to  diagnose  si- 
nusitis. We've  all  had  patients  who 
have  had  sinusitis,  and  it  does  seem  to 
resolve  very  nicely  with  removal  of 
the  tube.  Certainly,  very  few  patients 
require  sinus  taps  and  extremely  few 
require  operative  intervention,  in  my 
experience. 

Durbin:  I'd  like  to  ask  the  pediatric 
representative  in  our  group,  what  about 
nasal  intubation  in  kids?  For  a  while 
we  had  stopped  doing  it,  feeling  that 
oral  intubations  were  fine,  then  we 
stopped  using  as  much  sedation,  and 
found  that  oral  intubations  frequently 
resulted  in  unplanned  extubations. 
Now.  there  is  a  trend,  at  least  in  the 
cardiac  surgery  group  at  my  institu- 
tion, to  reinstitute  nasal  intubation  at 
the  end  of  the  operation.  What  do  you 
think  about  that? 

Thompson:  I  think  the  trends  are 
just  as  you  describe.  They  appear  to 
have  more  to  do  with  style  and  insti- 
tutional preference  than  data.  Many 
years  ago  there  was  a  study  that  looked 
at  the  frequency  of  inadvertent  extu- 
bation  in  neonates,  comparing  oral  and 
nasal  tubes.  I  recall  that,  surprisingly, 
there  was  no  difference.  Unfortu- 
nately. I  haven't  been  able  to  find  that 
reference.  Our  own  practice  has  shifted 
from  year  to  year,  again  more  in  re- 
action to  individual  events  than  as  a 
result  of  careful  study.  Another  point 
is  that  now  that  sinusitus  in  children  is 
a  well-established  entity,  the  signifi- 
cance of  this  complication  of  intuba- 
tion needs  to  be  clarified. 


Respiratory  Care  •  June  1999  Vol  44  No  6 


649 


Issues  in  Airway  Management  in  Infants  and  Children 


Ann  E  Thompson  MD 


Introduction 

Intubation 

Tube  Size 

Alternatives  to  Routine  Intubation 

Maintenance  and  Complications  of  Intubation 

Duration  of  Intubation 

Complications  Following  Extubation 

Airway  Infection,  Inflammation,  and  Edema 

Viral  Croup 

Bacterial  Tracheitis 
Infection 

Management  of  Airway  Injury 
Summary 

[Respir  Care  1999;44(6):650-658]  Key  words:  pediatric  airway,  cuffed  endo- 
tracheal tube,  complications,  nosocomial  infection,  tracheostomy,  laryngeal 
mask  airway. 


Introduction 

With  the  maturation  of  intensive  care  specialties,  airway 
management  has  become  a  routine  part  of  an  intensivist's 
responsibihties.  It  is  now  decades  since  deep  sedation, 
intubation,  and  maintenance  of  an  artificial  airway  have 
come  out  of  the  operating  room  and  into  the  intensive  care 
unit  and  emergency  department.  Gradually,  the  physio- 
logic impacts  of  analgesics  and  sedative/anesthetic  agents, 
laryngoscopy,  and  intubation  have  been  incorporated  into 
education  programs  and  algorithms  for  airway  manage- 
ment. Perhaps  somewhat  surprisingly,  recognition  and  skill 
at  managing  the  difficult  airway  lags  behind  understanding 
the  physiologic  risks  impacting  patient  safety.  In  an  era  of 
rapid  advances  in  understanding  the  molecular  basis  and 
treatment  of  disease,  complications  of  artificial  airways 
continue  to  add  morbidity  and  even  mortality  to  the  course 
of  critical  illness  in  infants  and  children.  In  addition,  these 
problems  add  to  the  cost  of  care.  To  the  extent  that  we  can 
minimize  their  occurrence,  we  can  decrease  resource  con- 


Ann  E  Thompson  MD  is  afTiliated  with  the  Division  of  Pediatric  Critical 
Care.  Children's  Hospital  of  Pittsburgh,  Pittsburgh,  Pennsylvania. 

Correspondence:  Ann  E  Thompson  MD,  Division  of  Pediatric  Critical 
Care,  Children's  Hospital  of  Pittsburgh.  3705  Fifth  Avenue,  Pittsburgh 
PA  15213-2.5.38.  E-mail:  thompson@smtp.anes.upmc.edu. 


sumption  while  improving  outcome.  This  paper  will  re- 
view some  of  the  persisting  problems  in  management  and 
attempt  to  identify  areas  that  need  further  attention. 

Intubation 


Although  the  vast  majority  of  children  have  structurally 
normal  airways,  normal  changes  significantly  with  the 
child's  physical  maturation.  Additionally,  among  the  chil- 
dren requiring  emergency  respiratory  intervention,  those 
with  abnormal  airways  are  overrepresented  because  of  re- 
spiratory problems  directly  related  to  the  structural  abnor- 
mality, as  well  as  their  frequent  association  with  other 
congenital  anomalies. 

Even  the  normal  infant  or  child  has  .several  airway  char- 
acteristics that  increase  the  risk  of  airway  obstruction  and 
may  make  intubation  difficult.  In  the  supine  position,  the 
child's  relatively  large  head  and  occiput  cause  neck  flex- 
ion and  increase  the  likelihood  of  airway  obstruction.  The 
relatively  flat  basicranium,  short  ramus  of  the  mandible, 
prominent  tonsils  and  adenoids,  and  relatively  large  tongue 
result  in  a  small  oropharyngeal  space.  The  epiglottis  is 
short,  narrow,  and  soft;  it  is  easily  deformed  onto  the 
tracheal  opening,  and,  along  with  supraglottic  tissues,  swells 
readily.  The  larynx  is  more  "anterior"  or  superior,  making 
laryngoscopy  more  difficult.  The  trachea  is  short  and  nar- 


650 


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Issues  in  Airway  Management  in  Infants  and  Children 


Infant 


Adull 


Inflornmation 
''        0,5        \ 


r 

t 

R  (notmol) 

1 

R  (inflamed) 

16 

1 8  monlfis 


Cricoid 


Nofrowest 

point 


Adult 

Fig.  1.  A:  The  basicranium  is  flat  in  the  infant,  limiting  the  size  of  the  oral  cavity.  The  ramus  of  the  mandible  increases  in  length  with  age. 
B:  The  epiglottis  descends  as  the  infant  matures.  C:  A  small  decrease  in  the  diameter  of  the  tracheal  lumen  has  a  much  greater  effect  on 
airways  resistance  in  the  infant  and  small  child.  D:  The  cricoid,  rather  than  the  vocal  cords,  is  the  narrowest  portion  of  the  trachea.  (Adapted 
from  Thompson  AE.  Pediatric  airway  management.  In:  Fuhrman  BP,  Zimmerman  JJ,  editors.  Pediatric  critical  care.  St  Louis:  Mosby; 
1992:107.) 


row,  making  malposition  of  an  artificial  airway  common, 
and  predisposing  to  markedly  increased  resistance  to  air 
flow  in  the  presence  of  minimal  edema  or  increased  se- 
cretions (Fig.  1). 

Many  children  who  experience  life-threatening  illness 
have  underlying  congenital  structural  anomalies,  often  in- 
volving the  face  and  airway.  Predictably,  difficult  airways 
occur  in  patients  with  micrognathia,  midline  facial  clefts, 
glossoptosis,  small  mouths,  limited  temporomandibular 
joint  mobility,  limited  neck  mobility,  or  asymmetrical  face. 
Acquired  causes  of  difficult  airways  include  upper  airway 
infection,  pharyngeal  masses,  facial  trauma,  juvenile  rheu- 
matoid arthritis,  and  a  variety  of  inborn  errors  of  metab- 
olism. Examining  every  child's  face  and  profile,  and  as- 
sessing mouth  and  neck  movement,  at  least  by  history,  will 
go  a  long  way  toward  anticipating  trouble  (Table  1).  Fi- 
beroptic laryngoscopy,  use  of  the  Bullard  laryngoscope, 
and  the  laryngeal  mask  airway  (LMA)  provide  alternatives 
to  conventional  laryngoscopy  that  should  be  familiar  to  the 
intensivist  and  will  be  addressed  below. 

Tube  Size 

Even  selecting  an  endotracheal  tube  of  the  correct  size 
is  less  straightforward  in  children  than  in  adults.  The  for- 


Table  I.       Recognizing  a  Child'.s  Difficult  Airway 

•  Micrognathia 

•  Midline  facial  cleft 

•  Glossoptosis 

•  Small  mouth 

•  Limited  neck  mobility 

•  Asymmetrical  f'acies 

•  Limited  temporomandibular  joint  mobility 

•  Upper  airway  infection 

•  Pharyngeal  masses 

•  Facial  trauma 

•  Juvenile  rheumatoid  arthritis 

•  Inborn  errors  of  metabolism 


mula.  internal  diameter  =  [age  (years)/4]  -I-  4,  is  the  best 
approximation  for  children  over  2,  while  published  guide- 
lines work  best  for  younger  infants  and  children.  Substi- 
tuting the  child's  "height-age"  (measuring  the  child's  length 
and  determining  the  age  at  which  this  length  would  be  at 
the  50th  percentile)  increases  the  accuracy  of  this  formula, 
but  is  rarely  done.  A  variety  of  estimates  based  on  the 
child's  size  have  been  suggested  for  those  who  only  have 
infrequent  opportunity  to  intubate  children.  A  tube  with  its 
diameter  equal  to  the  width  of  the  child's  fifth  t'lngemail  is 


Respiratory  Care  •  June  1999  Vol  44  No  6 


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Issues  in  Airway  Management  in  Infants  and  Children 


significantly  more  likely  to  be  appropriate  than  one  se- 
lected according  to  a  variety  of  earlier  recommendations. 
In  most  cases  there  should  be  a  leak  around  the  tube  at 
20-30  cm  H2O.'  Multiple  studies  have  indicated  that  the 
absence  of  a  leak  at  less  than  30-40  cm  HjO  is  highly 
predictive  of  postextubation  upper  airway  obstruction.^-'' 
Inter-observer  differences  in  assessing  the  leak  can  be  sub- 
stantial, however,  and  it  is  probably  appropriate  to  check 
the  leak  more  than  once  (or  by  more  than  one  observer) 
before  routinely  replacing  an  endotracheal  tube  or  making 
other  care  decisions.'* 

Because  the  narrowest  portion  of  the  child's  airway  is  at 
the  cricoid  (rather  than  at  the  vocal  cords,  as  in  adults), 
uncuffed  tubes  commonly  provide  an  adequate  fit  with 
minimal  loss  of  delivered  tidal  volume.  Traditional  rec- 
ommendations have  been  to  use  uncuffed  endotracheal 
tubes  in  children  less  than  8  years  old.  However,  in  an 
attempt  to  avoid  intubating  children  with  inappropriately 
large  tubes,  physicians  with  limited  pediatrics  experience 
often  select  a  tube  that  is  so  small  and  has  such  a  large  leak 
around  it  that  effective  ventilation  is  impossible.  Recent 
evidence  shows  that  cuffed  tubes  can  be  used  safely  in 
younger  children,  and  may  actually  decrease  the  risk  of 
complications,  at  least  in  the  short  term.''  Khine  et  al  rec- 
ommend using  the  following  formula  for  a  cuffed  tube: 
internal  diameter  =  (age  [years]/4)  +  3,  using  an  upward 
rounding  approach  to  age  (eg,  a  child  who  has  passed  his 
first  birthday  is  considered  to  be  2  years  old).*  In  the 
operating  room,  tube  selection  by  this  formula  is  appro- 
priate in  99%  of  patients,  allows  use  of  lower  gas  flow, 
and  minimizes  operating  room  anesthetic  gas  pollution. 
Although  the  risk  to  caretakers  is  minimal,  increasing  use 
of  nitric  oxide  in  the  pediatric  intensive  care  unit  (PICU) 
makes  the  environmental  issue  relevant  there  as  well.  Us- 
ing a  marginally  small  cuffed  tube  allows  one  the  choice 
of  inflating  the  cuff  or  not,  according  to  the  magnitude  of 
the  leak,  and  avoids  reintubation  for  tube  size  alone.  Al- 
though published  experience  in  the  PICU  is  extremely 
limited,  intubation  with  cuffed  tubes  for  more  prolonged 
periods  does  not  appear  to  be  associated  with  a  higher 
incidence  of  postextubation  stridor  or  airway  injury.  Cau- 
tion regarding  the  long-term  use  of  cuffed  tubes  remains 
necessary,  however:  avoidance  of  complications  depends 
on  meticulous  attention  to  minimizing  cuff  pressure  on  the 
tracheal  mucosa. 

Appropriate  depth  of  placement  is  also  important,  but  is 
often  overlooked  in  the  relief  of  success  in  placing  the  tube 
at  all.  Most  of  the  available  recommendations  lead  to  in- 
appropriate tube  placement  in  many  patients.  Excessively 
low  placement  is  often  associated  with  mainstem  bron- 
chial intubation,  massive  atelectasis,  pneumothorax,  and 
severe  hypoxemia.  A  tube  placed  too  high  is  more  likely  to 
be  dislodged.  One  suggestion  for  correct  placement  is  to 
multiply  the  endotracheal  tube  diameter  by  3  to  determine 


appropriate  depth.  Using  the  diameter  chosen  according  to 
the  age-based  formula  ([age/4]  -I-  4)  results  in  inappropri- 
ate placement  in  over  40%  of  patients;  using  the  height- 
age  formula  decreases  that  error  rate  to  about  20%.''  One 
of  the  simplest  and  best  suggestions  to  date  is  to  use  a  tube 
with  markings  along  its  entire  length,  and  place  the  3.0  cm 
mark  at  the  cords  for  all  infants  requiring  a  3.0-3.5  inter- 
nal diameter  tube,  at  4.0  cm  for  those  with  4.0-4.5  tubes, 
and  at  5.0  cm  for  those  with  5.0-5.5  tubes.^  Obtaining  a 
chest  x-ray  soon  after  intubation,  with  the  child's  head  in 
neutral  position,  is  strongly  recommended.'  Once  the  tube 
is  in  good  position,  noting  and  recording  its  depth  and 
making  sure  that  all  subsequent  x-rays  are  taken  in  the 
same  neutral  position  minimizes  further  need  for  x-rays 
(and  the  associated  exposure  and  cost). 

Even  with  the  tube  in  good  position,  right  upper  lobe 
atelectasis  is  common  in  infants  and  young  children.  While 
pooling  of  secretions  and  debris  in  a  small,  posteriorly 
angled  bronchus  is  often  the  cause,  a  recent  report  notes 
that  persistent  right  upper  lobe  atelectasis  in  children  can 
be  associated  with  a  tracheal  bronchus,  a  variation  occur- 
ring in  approximately  2%  of  the  population.'"  While  this 
would  rarely  be  a  problem  in  a  larger  patient,  the  length  of 
trachea  available  for  endotracheal  tube  placement  in  a  small 
child  is  sufficiently  short  that  the  potential  to  occlude  the 
bronchial  orifice  is  substantial. 

Alternatives  to  Routine  Intubation 

Blind  nasotracheal  intubation  has  been  recommended  in 
spontaneously  breathing  patients.  However,  it  has  also  been 
shown  to  be  less  likely  to  be  successful  than  orotracheal 
intubation,  even  in  adults,  and  to  prolong  the  time  neces- 
sary to  achieve  an  effective  airway.  In  conscious  children 
there  is  little  chance  of  cooperation,  and  in  those  with  an 
altered  level  of  consciousness,  the  delay  may  place  the 
child  at  increased  risk  of  secondary  hypoxia  complica- 
tions. The  success  rate  is  quite  low,  particularly  in  very 
young  children." 

Cricothyrotomy  is  another  approach  included  in  guide- 
lines for  emergency  airway  management  in  children,  but  is 
very  rarely,  if  ever,  necessary  or  indicated,  and,  in  fact,  it 
is  associated  with  a  high  risk  of  life-threatening  compli- 
cations.'^  In  patients  referred  to  our  institution,  attempted 
cricothyrotomy  in  the  field  has  been  associated  with  di- 
sastrous results,  and  each  of  the  patients  was  readily  intu- 
bated, via  the  orotracheal  route,  on  arrival  in  our  emer- 
gency department.  Efforts  to  improve  patient  outcome 
should  focus  on  teaching  other  airway  skills,  including 
bag- valve-mask  ventilation  and  orotracheal  intubation,  sup- 
ported by  some  newer  approaches,  in  preference  to  crico- 
thyrotomy. 


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Issues  in  Airway  Management  in  Infants  and  Children 


Table  2.      Algorithm  lor  Managing  the  Unexpected  Difficult  Airway 

•  Unrecognized  difficult  airway 

•  Cannot  mask  ventilate;  cannot  intubate 

•  Call  for  help 

•  Additional  attempt  at  intubation 

•  Place  laryngeal  mask  airway.  If  the  laryngeal  mask  airway  provides 
an  effective  airway,  any  of  the  several  alternative  approaches  to 
intubation  may  be  appropriate,  including  fiberoptic  laryngoscopy, 
retrograde  intubation.  "Seldinger"  approach,  the  Bullard 
laryngoscope.'*''-^" 

•  Transtracheal  jet  ventilation  (?] 

•  Surgical  cricothyrotomy  |?] 


Laryngeal  mask  airways  provide  a  valuable  alternative 
to  intubation  in  a  variety  of  settings.'^  The  use  of  LMAs  in 
the  operating  room  is  now  well-established.'-*  '"^  Placement 
in  children  is  somewhat  more  difficult  and  more  likely  to 
down-fold  the  epiglottis  (with  potential  tracheal  occlusion), 
but  with  the  recent  addition  of  the  size  1 .5,  there  is  a  mask 
that  will  fit  virtually  any  child.  A  prospective  study  of 
LMA  use  in  1.400  children  undergoing  induction  of  anes- 
thesia for  a  variety  of  surgical  procedures  demonstrated  a 
high  degree  of  success  and  safety,  even  when  placed  by 
trainees."^ 

For  the  purposes  of  this  discussion,  it  is  the  use  of 
LMAs  in  nonroutine  settings  that  is  particularly  notewor- 
thy. Experience  in  adults  has  been  successful  enough  to 
include  the  LMA  in  guidelines  for  resuscitation  and  the 
difficult  airway  algorithm  for  failed  intubation  developed 
by  the  American  Society  of  Anesthesiologists  (Table  2). 
Appropriate  placement  rate  has  been  very  high  for  expe- 
rienced personnel,  but  also  for  nurses,  paramedics,  and 
residents  with  limited  practice. 

The  LMA  has  been  shown  to  facilitate  fiberoptic  bron- 
choscopy and  simultaneous  ventilatory  support  in  young 
children,  and  to  permit  passage  of  a  larger  bronchoscope 
for  lavage  and  biopsy  than  would  be  possible  through  an 
endotracheal  tube  fitting  the  child. '^  The  LMA  can  pro- 
vide effective  airway  support  in  patients  with  extremely 
difficult  airways  as  well,  and  is  sometimes  adequate  as  the 
definitive  method  for  maintaining  an  airway  or  as  a  tran- 
sitional step  before  fiberoptic  intubation  or  tracheotomy 
(see  Table  2).'» 

The  literature  contains  multiple  reports  of  use  of  the 
LMA  in  children  with  extremely  difficult  airways,  includ- 
ing some  with  the  Robin  sequence.  Goldenhar's  syndrome, 
Treacher-Collins's  syndrome,  juvenile  rheumatoid  arthri- 
tis, and  facial  trauma.  In  our  institution,  we  have  had  good 
experience  in  a  child  with  the  Robin  sequence  in  combi- 
nation with  arthrogryposis  (Fig.  2),  and  in  another  with 
craniocostomandibular  syndrome.  (Fig.  3).  Once  control 
of  the  airway  is  achieved,  the  LMA  often  allows  more 
controlled  attempts  to  intubate  the  patient  using  fiberoptic 


Fig.  2.  Infant  with  Robin  sequence  and  arthrogryposis.  Arrows 
indicate  limited  mouth  opening  and  restricted  neck  movement  sec- 
ondary to  shortened  neck  musculature  and  tendons. 


bronchoscopy,  or,  on  rare  occasions,  proceeding  to  tra- 
cheotomy without  intubation. 

Experience  in  the  delivery  room  with  neonatal  resusci- 
tation has  demonstrated  that  the  LMA  can  be  a  good  al- 
ternative to  tracheal  intubation.  With  the  LMA,  personnel 
with  limited  experience  obtain  a  clear  airway  more  rap- 
idly, with  fewer  failures,  and  with  more  rapid  improve- 
ment in  oxygenation.''^--"  Becau.se  of  its  limited  ability  to 
provide  an  effective  seal  when  positive  pressure  is  applied, 
the  LMA  may  not  be  appropriate  for  ventilating  infants 
and  children  with  severe  lung  pathology.  In  addition,  when 
there  is  severe  laryngeal  or  tracheal  obstruction,  the  LMA 
might  not  be  useful. 

The  Bullard  laryngoscope  uses  fiberoptic  technology 
rather  than  direct  visualization  to  visualize  the  larynx.  Its 
shape  follows  the  anatomy  of  the  oropharynx,  and  it  in- 
corporates a  stylet  that  aligns  the  endotracheal  tube  and  the 
airway.  In  the  hands  of  an  experienced  practitioner,  it  can 
be  a  very  valuable  tool  for  a  difficult  airway,  but  few 
people  outside  the  operating  room  have  mastered  its  use. 
Fiberoptic  bronchoscopy  is  another  very  valuable  addition 
to  airway  management,  either  alone  or  with  the  LMA.  It, 
too,  requires  developing  and  maintaining  the  appropriate 
technique. 


Respiratory  Care  •  June  1999  Vol  44  No  6 


65.'^ 


Issues  in  Airway  Management  in  Infants  and  Children 


Fig.  3.  Infant  with  craniofacial  abnormalities.  A:  Severe  micrognathia.  B:  Laryngeal  mask  airway.  C:  Chest  radiograph  showing  laryngeal 
mask  in  pharynx. 


Maintenance  and  Complications 

The  relative  merit.s  of  nasotracheal  and  orotracheal  in- 
tubation are  unclear.  Na.sotracheal  tubes  may  be  more  sta- 


ble, but  associated  with  a  higher  rate  of  sinusitis.  Although 
strongly  held  beliefs  guide  decisions  about  nasal  versus 
oral  tubes,  at  least  with  regard  to  infection,  the  data  are 


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Issues  in  Airway  Management  in  Infants  and  Children 


inadequate  to  support  one  course  over  the  other.  Current 
Centers  for  Disease  Control  and  Prevention  guidehnes  for 
preventing  nosocomial  infection  do  not  make  a  recom- 
mendation about  the  route  of  intubation,  citing  inadequate 
data.-'  Oral  tubes  are  more  irritating  to  most  patients,  elic- 
iting more  frequent  gagging  and  coughing,  and  may  be 
more  readily  dislodged.  Since  their  use  is  often  in  con- 
junction with  nasogastric  tubes,  it  is  not  clear  that  the  risk 
of  sinus  infection  is  any  less  for  these  patients. 

Duration  of  Intubation 

Safe  duration  of  intubation  is  not  quantifiable.  "Pro- 
longed intubation"  once  meant  intubation  beyond  the  re- 
covery room,  but  the  term's  meaning  has  gradually  been 
extended.  While  some  patients  will  suffer  airway  injury  at 
intubation  or  shortly  afterwards,  many  will  not  experience 
significant  injury  even  when  intubated  for  weeks  or  months. 
In  a  study  of  2,791  infants  and  children  undergoing  naso- 
tracheal intubation  in  a  PICU  in  one  institution  over  a 
4-year  period,  Black  et  al  noted  an  overall  complication 
rate  of  8%.--  The  most  common  problems  were  inadver- 
tent extubation  and  tube  obstruction.  Stridor  occurred  in 
less  than  2%  of  patients,  and  less  than  1%  required  rein- 
tubation  for  severe  upper  airway  obstruction.  Four  percent 
of  the  patients  underwent  tracheotomy,  over  half  for  pre- 
existing airway  problems,  and  the  remainder  for  very  long- 
term  ventilation.  Meticulous  attention  to  the  presence  of  a 
leak  around  the  tube  was  central  to  their  approach. 

Factors  predisposing  to  airway  injury  include  preexist- 
ing inflammation,  trauma  at  the  time  of  intubation,  muco- 
sal injury  with  edema,  inflammation,  immunocompromise, 
and  ulceration  (particularly  along  the  tracheal  cartilages 
and  at  the  level  of  the  cuff).  Microbial  colonization  of 
ulcerated  areas,  suctioning  procedures,  and  episodes  of 
hypoperfusion  all  contribute  to  the  potential  for  further 
infection  and  injury,  including  necrosis,  granuloma  forma- 
tion, and  scarring. 2'' 

Complications  Following  Extubation 


Treatment  with  aerosolized  epinephrine  decreases  air- 
way edema  and  often  provides  effective  relief  of  stridor 
and  respiratory  distress.  For  patients  with  transient  or  in- 
adequate response  to  epinephrine,  an  inspired  mixture  of 
helium  and  oxygen  (heliox)  is  often  dramatically  and  im- 
mediately beneficial.-''  Heliox  has  a  lower  density  and 
higher  kinetic  viscosity  than  nitrogen-oxygen  mixtures. 
These  properties  permit  higher  respiratory  gas  flow  rates, 
with  less  turbulence  for  a  given  pressure,  and  decrease  the 
work  of  breathing  through  a  narrowed  air  passage.  Even 
when  turbulent  flow  does  develop,  heliox  delivers  more 
oxygen  than  nitrogen-oxygen  mixtures.-''  In  a  randomized 
controlled  crossover  trial,  heliox  was  superior  to  air-oxy- 
gen mixtures  for  relieving  postextubation  stridor  in  chil- 
dren after  trauma-^^*  In  our  experience,  heliox  has  been 
very  useful  in  similar  settings,  as  well  as  in  patients  with 
more  distal  airway  obstruction. 

The  existing  data  about  the  value  of  systemic  steroids 
are  conflicting.  In  a  double-blind,  prospective,  random- 
ized, placebo-controlled  trial,  Anene  et  al  found  a  lower 
incidence  of  stridor,  lower  croup  score,  decreased  pulsus 
paradoxus,  and  a  less  frequent  requirement  for  aerosolized 
epinephrine  or  reintubation.-^  However,  their  control  group 
had  an  unusually  high  reintubation  rate  (7/32,  or  22%) 
Although  this  frequency  of  upper  airway  obstruction  after 
extubation  is  similar  to  that  reported  by  others  (25-37%),  our 
reintubation  rate  for  airway  obstruction  is  only  10-15%. 

Since  the  vast  majority  of  patients  can  be  extubated 
without  difficulty,  steroids  should  probably  be  reserved  for 
those  with  a  failed  trial  of  extubation,  or  for  those  who 
have  no  leak  around  the  endotracheal  tube  in  the  hours 
preceding  a  planned  extubation. 

Obstruction  can  also  result  from  tracheomalacia,  partic- 
ularly in  infants  exposed  to  high  airway  pressure  for  an 
extended  period.  These  patients  often  improve  spontane- 
ously, but  may  require  continuous  positive  airway  pres- 
sure, bi-level  positive  airway  pressure,  or  full  mechanical 
ventilation  for  an  extended  period.  Damage  to  the  palate 
and  developing  teeth  is  also  common,  including  among 
infants  without  teeth  at  the  time  of  airway  manipulation.-"' 


The  most  immediately  threatening  complication  follow- 
ing extubation  is  severe  upper  airway  obstruction.  Koka 
found  that  factors  increasing  the  risk  of  postextubation 
stridor  in  children  after  surgery  included  age  under  4  years, 
trauma  related  to  laryngoscopy  and  tube  placement,  dura- 
tion of  intubation,  and  absence  of  an  air  leak  around  the 
endotracheal  tube.-^  In  the  operating  room  at  least,  the 
frequency  of  postextubation  stridor  has  decreased  dramat- 
ically since  that  study,  at  least  in  pediatric  centers,  to 
0.1%!^^  Although  obstruction  following  more  prolonged 
intubation  in  the  PICU  is  much  less  frequent  than  in  the 
past,  a  small  percentage  of  patients  experience  significant 
respiratory  distress,  and  some  need  reintubation. 


Airway  Infection,  Inflammation,  and  Edema 

Viral  Croup 

Contrary  to  early  recommendations,  most  patients  with 
viral  laryngotracheobronchitis  (croup)  can  be  safely  sup- 
ported with  endotracheal  intubation  rather  than  tracheos- 
tomy, but  routinely  require  a  smaller  tube  than  predicted 
by  age  (typically  1  mm  smaller  in  diameter).  In  a  review 
of  over  200  children  who  were  intubated  for  severe  croup 
over  a  10-year  period.  McEniery  noted  that  only  27  pa- 
tients (13%)  required  tracheotomy,  10  had  subglottic  nar- 
rowing that  precluded  passage  of  even  a  3.0  mm  tube,  and 


Respiratory  Care  •  June  1 999  Vol  44  No  6 


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Issues  in  Airway  Management  in  Infants  and  Children 


]7  had  experienced  severe  endotracheal  tube  trauma.'"  Of 
these  patients  only  2.5%  developed  subglottic  stenosis, 
and  only  1  patient  needed  a  very  long-term  tracheostomy 
tube. 

As  the  u.se  of  corticosteroids  for  viral  croup  has  in- 
creased, the  frequency  of  illness  severe  enough  to  require 
intubation  has  decreased.'-  While  a  report  of  outpatient 
treatment  of  croup  with  nebulized  dexamethasone  recom- 
mended against  treatment,''''  more  recent  studies  (one  by 
the  same  group),  including  an  excellent  randomized,  con- 
trolled, and  double-blind  study,  have  shown  clear  benefit 
from  systemic  steroids  in  decreasing  hospitalization  for 
croup.'-*  A  similar  study  provides  a  rationale  for  their  use 
in  children  who  require  intubation.''' 

Bacterial  Tracheitis 

Community-acquired  bacterial  tracheitis  is  a  relatively 
newly  recognized  entity,  commonly  caused  by  Staphyloc- 
ciis  aureus,  Staphyloccus  pyogenes,  and  occasionally  by 
Staphyloccus  pneumoniae,  associated  with  a  mortality  rate 
as  high  as  20%,  largely  related  to  acute,  complete  upper 
airway  obstruction,  but  also  occasionally  to  associated  sep- 
tic shock  or  acute  respiratory  distress  syndrome.  Good 
outcome  depends  on  maintaining  a  patent  airway.  Although 
some  controversy  persists,  endotracheal  intubation  appears 
to  provide  adequate  support,  as  long  as  meticulous  atten- 
tion is  given  to  keeping  the  endotracheal  tube  clear  of  the 
thick,  purulent  secretions."' "  Although  some  practitioners 
advocate  tracheostomy,  incising  the  tracheal  mucosa  and  an- 
terior tissues  of  the  neck  would  seem  to  provide  a  portal  for 
deeper  and  potentially  necrotizing  cartilaginous  infection. 

Infection 

While  one  major  indication  for  an  artificial  airway  is  to 
support  patients  with  severe  infection,  both  endotracheal 
tubes  and  tracheostomy  tubes  (with  or  without  mechanical 
ventilation)  are  also  associated  with  an  increased  risk  of 
nosocomial  respiratory  infection.  The  incidence  of  noso- 
comial pneumonia  and  tracheitis  is  much  lower  in  children 
than  in  adults  admitted  to  intensive  care  units:  only  1-3% 
of  children  admitted  to  PICUs  develop  nosocomial  lower 
respiratory  infection.'""'  However,  this  increases  to  7-8% 
in  patients  ventilated  for  3  days  or  more.  Specific  risk 
factors  for  pneumonia  include  immunodeficiency,  immu- 
nosuppression, and  neuromuscular  blockage;  for  trache- 
itis, respiratory  failure  and  head  trauma  increase  risk  (Ta- 
ble 3)."'-*" 

Although  relatively  uncommon,  pneumonitis  and  tra- 
cheitis increase  resource  utilization  (antibiotics,  reintuba- 
tion).  length  of  stay,  and  even  mortality.  Although  organ- 
isms from  the  pharynx  probably  enter  the  larynx  and  trachea 
constantly,  local  defense  mechanisms,  including  mucoid 


Table  3.      Risk  Factors  for  Nosocomial  Tracheitis  and  Pneumoniti: 


Bacterial  nosocomial  pneumonia  Bacterial  nosocomial  tracheitis 


Immimodepressanl  drugs 
Immunodeficiency 
Neuromuscular  blockade 
Age  less  than  2  months 


Head  trauma 
Respiratory  failure 


(Adapted  IVom  Reference  ^H.) 


secretions,  ciliary  action,  and  immunoglobulin  A,  effec- 
tively clear  the  airway  of  pathogens  most  of  the  time. 
However,  potential  pathogens,  including  Haemophilus  in- 
fluenzae, S.  pyogenes  group  A,  S.  pneumoniae,  S.  aureus, 
and  Moraxella  catarrlmlis,  can  be  suctioned  from  the  lar- 
ynx or  trachea,  or  both,  in  healthy  children,  suggesting  that 
even  they  may  be  colonized  below  the  pharynx. 

Airway  instrumentation,  even  briefly,  may  introduce 
pathogens-"  and  interfere  with  protective  functions.  In  chil- 
dren requiring  long-term  ventilation,  colonization  of  the 
lower  airway  is  nearly  universal,  although  the  organisms 
vary,  depending  on  local  hospital  flora.  The  microorgan- 
isms cultured  most  frequently  include  the  flora  listed  above, 
but  also  a  wide  variety  of  Gram-negative  bacilli,  including 
Pseudomonas,  Acinetobacter.  and  Stenotrophomonas. 
Much  of  the  colonization  and/or  infection  is  exogenous 
rather  than  from  the  oropharynx;  the  oropharyngeal  colo- 
nization may  be  different  from  that  in  the  lower  airway. 
Oral/enteral  decontamination  is  inejfective  in  preventing 
respiratory  colonization  or  infection  with  environmental 
agents,  and  systemic  antibiotics  fail  to  eradicate  the  carrier 
state.-'^ 

Some  organisms,  including  Pseudomonas  and  other 
Gram-negative  bacteria,  have  a  particular  propensity  for 
colonizing  the  lower  airway  rather  than  the  oropharynx, 
even  when  there  is  ready  access  to  both.  This  predilection 
may  be  enhanced  in  patients  with  a  tracheostomy  and  as- 
sociated skin  wound,  foreign  body  in  the  airway,  exposure 
of  the  tracheal  mucosa  to  the  atmosphere,  change  in  the  pH 
of  the  mucus,  mucus  stasis,  or  lepeated  instrumentation 
and  irritation  during  suctioning.  The  greater  frequency  of 
Gram-positive  organisms  in  children  may  reflect  preser- 
vation of  fibronectin  on  the  oral  mucosa  to  a  greater  extent 
than  is  seen  in  many  adults  with  chronic  diseases  and 
tracheostomies. 

Sinusitis  in  intubated  children  is  poorly  characterized. 
However,  it  is  responsible  for  episodes  of  sepsis  that  are 
difficult  to  localize.  Particularly  in  the  case  of  infants  with 
minimal  sinus  pneumatization,  diagnosis  is  difficult  but 
can  be  important.-"  Responsible  organisms  are  quite  dis- 
tinct from  those  associated  with  community-acquired  in- 
fection,-*-*  but  are  similar  to  the  organisms  associated  with 
nosocomial  tracheitis  and  pneumonitis.  Aerobes  include  S 


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Respiratory  Care  •  June  1999  Vol  44  No  6 


Issues  in  Airway  Management  in  Infants  and  Children 


aureus,  Pseudomonas  aeruginosa,  Escherichia  coli,  and 
Klebsiella  pnem,toniae.  Anaerobes  include  Peptostrepto- 
coccus  species,  Prevotella  species,  and  Fusohacterium  spe- 
cies and  are  especially  likely  to  be  cultured  from  children 
intubated  for  more  than  2  weeks.-''^  To  date  there  has  been 
no  systematic,  prospective  study  to  evaluate  the  frequency 
and  complications  of  nosocomial  sinusitis  in  children. 

The  ubiquitous  presence  of  airway  pathogens  makes 
treatment  decisions  about  febrile  PICU  patients  difficult. 
While  the  risks  of  delay  or  undertreatment  include  uncon- 
trollable infection,  overtreatment  contributes  to  develop- 
ment of  resistant  organisms  in  the  individual  patient  and 
environment,  and  increases  the  cost  of  care.  Additional 
study  is  needed  regarding  the  threshold  for  and  benefit  of 
treating  nosocomial  bacterial  tracheitis. 

Management  of  Airway  Injury 

When  significant  laryngotracheal  injury  does  occur,  tra- 
cheotomy may  provide  a  stable  airway  while  growth  and 
healing  occur.  Tracheotomy  itself  is  not  benign;  in  infants 
(less  than  1  year  old)  the  mortality  rate  is  still  approxi- 
mately S^.-""  There  appears  to  be  no  role  for  tracheotomy 
in  the  first  3-6  weeks  of  support  in  patients  without  pre- 
existing upper  airway  disease.  At  present,  the  primary  in- 
dications for  tracheostomy  in  acutely  ill  infants  and  chil- 
dren are  comfort,  improved  airway  stability,  and  increased 
freedom  of  movement  for  the  child.  Additional  indications 
include  a  need  for  chronic  mechanical  ventilation  and  im- 
proved access  to  the  airway  for  suctioning  in  patients  with 
impaired  protective  reflexes.  Clinical  investigation  is 
needed  to  determine  tracheostomy's  potential  to  decrease 
the  need  for  sedation  and  the  duration  of  mechanical  ven- 
tilation in  children  requiring  prolonged  intensive  care. 

When  the  initial  indication  for  tracheotomy  has  resolved, 
most  patients  can  be  decannulated  without  difficulty.  Failed 
decannulation  is  most  likely  to  result  from  granulation 
tissue;  acquired  stenosis  or  webbing;  tracheomalacia  or 
tracheal  flap;  or  vocal  cord  paralysis,  fixation,  or  disloca- 
tion.-*^ Bronchoscopy  prior  to  decannulation  by  an  expe- 
rienced pediatric  otolaryngologist  is  essential  for  identify- 
ing residual  problems  and  developing  a  treatment  plan. 

In  the  small  number  of  children  with  persistent  severe 
airway  obstruction,  a  variety  of  surgical  procedures  are 
available  to  restore  a  functional  upper  airway.  Depending 
on  the  specific  abnormality,  cricoid  split,  anterior  cartilage 
rib  grafting,  and  laryngotracheoplasty  are  options  for  re- 
pair or  reconstruction.  Although  multiple  procedures  may 
be  necessary  and  voice  quality  may  be  impaired,  results 
are  generally  good.^**  Approximately  909r  are  decannu- 
lated successfully. 


Summary 

Airway  management  is  a  routine  part  of  intensive  care. 
In  an  era  of  remarkable  success  caring  for  children  with 
life-threatening  conditions,  including  severe  respiratory 
failure,  sepsis,  childhood  cancer,  complex  congenital  heart 
disease,  and  end-stage  organ  dysfunction  and  transplanta- 
tion, airway  management  remains  critically  important. 
However,  many  questions  remain  regarding  best  practice, 
and  complications  related  to  artificial  airways  continue  to 
increase  intensive  care  unit  stay,  morbidity,  and  mortality. 
Despite  a  lack  of  associated  glamour,  continued  attention  to 
this  aspect  of  caring  for  critically  ill  children  is  essential. 

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Discussion 

Stauffer:  What  is  the  experience 
with  the  natural  course  of  tracheal  ste- 
nosis in  children?  If  a  child  has,  for 
example,  a  tight  tracheal  stricture  at 
the  age  of  2  or  3,  what  happens  to  the 
stricture?  Does  it  grow  as  the  child 
grows  so  that  there  might  not  be  prob- 
lems when  they're  a  teenager,  or  does 


it  stay  small  and  create  the  need  for 
reconstructive  surgery? 

Thompson:  It  depends  on  the  etiol- 
ogy and  severity  of  the  problem.  Most 
of  the  children  born  with  a  severe  up- 
per airway  abnormality  won't  survive 
to  age  2  or  3  without  intervention.  If 
subglottic  stenosis  develops  as  a  con- 
sequence of  airway  injury  related  to 
intubation,  the  need  for  intervention  is 


determined  by  the  severity  of  steno- 
sis. Mild  stenosis  may  cause  mild  stri- 
dor but  no  need  for  treatment,  and  may 
resolve  with  growth.  More  severe  ste- 
nosis or  progression  of  mild  stenosis 
often  requires  tracheostomy  to  bypass 
the  airway  obstruction  until  sufficient 
growth  occurs.  Some  cases  are  suffi- 
ciently severe  and/or  progressive  that 
tracheal  dilatation  and/or  reconstruc- 
tion is  necessary.  Most  of  these  pro- 


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Issues  in  Airway  Management  in  Infants  and  Children 


cedures  are  done  in  very  early  child- 
hood, rather  than  waiting  until  growth 
is  complete,  in  order  to  minimize  the 
impact  of  a  chronic  tracheostomy  on 
communication  and  other  develop- 
mental milestones  and  childhood  ac- 
tivity. 

Stauffer:  I  think  your  comments 
about  tracheal  stenosis  were  in  refer- 
ence to  something  below  the  cricoid, 
correct? 

Thompson:  No,  it  would  be  both. 
Well,  which  comments? 

Stauffer:  Did  I  correctly  understand 
from  your  slide  presentation  that  tra- 
cheal stenosis  and  tracheomalacia  oc- 
cur even  though  many  kids  are  intu- 
bated with  uncuffed  tubes? 

Thompson:  That's  right.  The  most 
common  site  of  injury  is  at  the  level 
of  the  cricoid,  presumably  because 
that's  the  point  of  greatest  pressure  on 
the  tracheal  wall.  Tracheomalacia  def- 
initely occurs  in  children  who  have 
never  had  cuffed  tubes  and  seems  to 
correlate  with  the  level  of  positive 
pressure  required  for  ventilation.  Ap- 
parently the  positive  pressure  of  me- 
chanical ventilation  is  sufficient  to  di- 
late and  damage  the  cartilaginous 
structure. 

Stauffer:  What  is  the  experience 
with  glottic  ulceration  and  subsequent 
glottic  stenosis  in  children  intubated 
for  3  to  6  weeks  or  longer? 

Thompson:  Within  the  glottis,  the 
vocal  cords  are  where  we  see  prob- 
lems most  frequently.  Occasionally, 
we  also  note  web  formation  within  the 
glottis.  In  the  1,200  intubated  patients 
a  year  that  we  care  for,  severe  glottic 
pathology  is  quite  uncommon,  except 
in  head  injury  patients,  where  I  think 
we  are  dealing  with  neurologic  com- 
promise to  vocal  cord  function  rather 
than  endotracheal  tube  damage.  Prob- 
lems do  occur,  but  they  are  uncommon. 


Reibel:  You  may  be  surprised,  but  I 
don't  disagree  with  you  at  all  on  the 
slash  airway  for  pediatric  patients.  In 
that  situation,  not  only  the  child,  but 
the  surgeon  is  in  extremis.  Fortunately, 
I  don't  think  we've  had  occasion  to  do 
one  in  the  last  8-10  years  at  Univer- 
sity of  Virginia.  Now,  that's  from  oto- 
laryngology— I  don't  know  what  the 
pediatric  surgeons'  experience  has 
been.  I  can't  recall  one.  We've  always 
been  able  to  temporize,  but  that's  an 
awful  situation.  In  regard  to  the  last 
question,  about  isolated  posterior  glot- 
tic pathology,  I  don't  believe  that's  an 
isolated  problem  in  the  pediatric  pa- 
tient. My  colleague  Charlie  Gross  does 
most  of  the  pediatric  otolaryngology 
in  our  institution,  and  he  talks  fre- 
quently about  the  kids  with  borderline 
subglottic  stenosis  who  have  recurrent 
croup.  He  emphasizes  to  the  residents 
and  the  pediatricians  not  to  instrument 
these  children  and  intubate  them  be- 
cause one  then  takes  a  borderline  sit- 
uation and  has  them  get  edema  and 
submucosal  fibrosis  that  further  com- 
promises their  airway  and  likely  puts 
them  in  a  surgical  condition  where  they 
have  to  have  a  tracheostomy. 

Thompson:  Let  me  clarify  that  it's 
neither  our  pediatric  surgeons  nor  oto- 
laryngologists who  have  done  "slash" 
tracheotomies  or  cricothyrotomies. 
These  procedures  have  been  per- 
formed outside  of  our  hospital  by  prac- 
titioners who  do  not  care  for  children 
very  often,  who  are  faced  with  emer- 
gency airway  problems  in  community 
settings,  and  who  are  no  doubt  faced 
with  terrifying  circumstances.  My  con- 
cern is  that  we  continue  to  teach  these 
procedures  as  alternatives  for  airway 
control,  even  though  the  outcome  is 
so  poor.  We  should  actively  discour- 
age use  of  these  procedures,  and  en- 
courage practitioners  to  improve  their 
bag-valve-mask  skills,  get  experience 
intubating  children  under  elective  con- 
ditions in  the  operating  room  or  on 
pediatric  mannequins,  and  learn  the 
use  of  the  LMA. 


Heffner:  Ann,  is  there  any  role  for 
the  LMA  as  a  guide  for  intubation?  In 
adults  there  certainly  is,  but  I  don't 
know  whether  that's  still  possible  with 
a  smaller  airway. 

Thompson:  The  LMA  is  certainly 
valuable  as  a  guide  for  intubation  in 
children,  although  becoming  accom- 
plished requires  substantial  experi- 
ence. In  that  infant  I  discussed  who 
had  extreme  micrognathia,  the  LMA 
served  as  an  excellent  guide  for  using 
a  fiberoptic  scope,  but  that  procedure 
was  done  by  a  highly  skilled  endos- 
copist. One  disadvantage  of  the  LMA 
is  that,  because  the  epiglottis  is  soft 
and  tloppy  in  an  infant,  the  likelihood 
of  LMA  malposition  is  fairly  high.  In 
most  cases  this  does  not  interfere  with 
effective  ventilation,  but  may  make  vi- 
sualizing the  airway  very  difficult. 

Heffner:  In  children,  do  you  use  an 
LMA  to  place  the  initial  airway  and 
then  place  the  endotracheal  tube 
through  the  LMA? 

Thompson:  One  can  pass  the  endo- 
tracheal tube  directly  through  the  con- 
nector of  the  LMA.  or  pass  an  endo- 
tracheal tube  over  the  bronchoscope, 
the  bronchoscope  through  the  LMA 
into  the  airways,  and  then  the  endo- 
tracheal tube  over  the  bronchoscope 
into  the  trachea.  For  diagnostic  bron- 
choscopy, use  of  the  LMA  allows  bet- 
ter ventilation  and  permits  passage  of 
a  larger  bronchoscope  with  more  fea- 
tures (including  suction)  than  is  pos- 
sible if  the  bronchoscope  must  be  ad- 
vanced through  an  endotracheal  tube. 

Hurford:  You  spoke  earlier  about 
differences  in  airway  management  be- 
tween adults  and  children,  and  it's  sur- 
prising how  similar  the  approaches  ac- 
tually are.  especially  when  it  comes  to 
the  difficult  airway.  I  think  that  the 
care  we've  given  to  adults  has  sort  of 
gone  off  the  path  a  bit.  and  now  they 
are  coming  closer  together.  The  points 
you  make  on  the  LMA  and  cricothy- 
roidotomy  are  extremely  well  made. 


Respiratory  Care  •  June  1999  Vol  44  No  6 


659 


Issues  in  Airway  Management  in  Infants  and  Children 


and  apply  to  the  adult  as  well.  At  a 
group  that  we  had  at  the  Harvard  hos- 
pitals, we  sought  out  cases  where  a 
cricothyroidotomy,  and  specifically 
needle  cricothyroidotomy  followed  by 
jet  ventilation,  was  effective  as  an 
emergency  airway  adjunct.  And  the 
only  thing  that  we  could  come  up  with 
was  6  deaths  due  to  the  cricothyroid- 
otomy, and/or  the  jet  ventilation  and 
the  complications  that  ensued.  In  my 
personal  experience,  whenever  we've 
had  a  difficult  airway,  I've  been  going 
back  and  examining  the  patient.  I  of- 
ten can't  easily  find  the  cricothyroid 
membrane  in  those  patients.  The  same 
reasons  that  they  were  difficult  intu- 
bations in  the  first  place  also  make 
them  very  difficult  as  far  as  neck  anat- 
omy in  finding  the  cricothyroid  mem- 
brane. It  would  be  very  difficult  for 
me  to  imagine  being  able  to  do  that 
reliably,  and  in  a  kid,  I  couldn't  con- 
ceive of  it.  So  I  think  that's  an  impor- 
tant point,  too.  What  is  the  longest 
period  of  time  you've  kept  LMAs  in 
children  without  an  alternative  airway? 
Do  you  do  that  for  a  long  period  of 
time,  and  if  so,  is  your  preference  to 
intubate  as  you've  just  described, 
and/or  to  go  on  to  a  tracheostomy  in 
those  cases? 

Thompson:  My  experience  with  the 
LMA  is  only  as  a  temporizing  maneu- 
ver. While  some  people  may  extend 
its  use,  our  practice  has  been  to  use  it 
to  administer  an  anesthetic  or  as  a 
means  of  controlling  the  airway  until 
a  more  secure  airway  is  achieved.  In 
children  with  a  need  for  longer  term 
ventilation,  problems  with  discomfort. 


risk  of  aspiration,  and  gastric  disten- 
sion would  all  discourage  the  LMA  as 
a  long-term  solution. 

Hurford:  Once  you've  intubated 
through  the  LMA,  how  do  you  get  the 
LMA  out? 

Thompson:  We've  had  a  few  ap- 
proaches to  that.  Since  most  patients 
have  gone  on  to  tracheostomy  because 
of  difficult  airways,  we've  left  the 
LMA  in  place  until  the  tracheostomy 
tube  is  secure  and  then  removed  ev- 
erything else  together.  In  2  other  pa- 
tients we  used  a  sort  of  Seldinger  tech- 
nique, placing  a  guide  wire  into  the 
trachea  to  make  sure  that  we  could 
replace  the  endotracheal  tube  if  we 
lost  it  at  the  time  of  LMA  removal. 

Stoller:  I  have  2  numbers  questions. 
I  was  unaware  of  the  rule  of  thumb 
about  age  over  4  plus  4  as  an  index  to 
the  inner  diameter  guideline.  But,  I 
was  interested  to  note  that  this  same 
regression  equation,  age  over  4  plus 
4,  is,  of  course,  the  mean  alveolar- 
arterial  gradient  for  an  adult.  So  per- 
haps age  over  4  plus  4  is  the  tt  of 
respiratory  physiology.  My  second 
question  regards  the  prevalence  esti- 
mate you  cited  of  a  pig  bronchus.  My 
personal  experience  with  bronchos- 
copy is  probably  in  the  area  of  several 
thousand  at  this  point,  and  I  suspect 
that  in  this  room,  our  collective  expe- 
rience is  probably  in  the  tens  of  thou- 
sands. With  that  denominator  of  clin- 
ical experience,  I  find  the  cited 
prevalence  of  2%  pretty  hard  to  be- 
lieve. So,  I'm  interested  in  where  that 


number  came  from  and  whether  we 
believe  it.  I  can  recall  only  2  instances 
of  seeing  such  an  anatomic  variant  in 
my  experience. 

Thompson:  I  read  this  in  the  paper 
by  O'Sullivan.'  I  don't  have  your  bron- 
choscopy experience,  so  I  can't  really 
comment  about  my  own  patients.  Right 
upper  lobe  atelectasis  is  extremely 
common  in  young  children;  I've  al- 
ways assumed  this  is  related  to  its  small 
bronchus  being  angled  posteriorly  in 
a  supine  patient,  collecting  secretions. 
However,  after  encountering  this  pa- 
per, I  had  2  patients  in  a  row  with  the 
tracheal  bronchus  and  right  upper  lobe 
atelectasis.  So,  in  my  series  of  2,  the 
incidence  was  100%! 

REFERENCE 

1.  O'Sullivan  BP.  Frassica  JJ,  Rayder  SM. 
Tracheal  bronchus:  a  cause  of  prolonged 
atelectasis  in  intubated  children.  Chest 

1998;113(2):537-540. 

Stoller:  Well,  that's  like  the  old  aph- 
orism I  tell  my  residents.  If  you  have 
one  case,  it's  a  case  report;  two,  it's  a 
ca.se  series;  three,  it's  case  after  case 
after  case. 

Reibel:  At  your  institution,  have  you 
taken  a  percutaneous  dilatational  tra- 
cheotomy below  the  low  fence  of  age 
1 5  or  16  and  been  trying  to  apply  that 
in  adolescent  older  children? 

Thompson:  As  far  as  I  know,  we 
have  not  done  it  in  our  institution  at 
all.  I'm  trying  to  think  whether  I've 
encountered  it  in  somebody  sent  in 
from  the  outside,  and  I  think  not. 


660 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Special  Purpose  Endotracheal  Tubes 


J  Michael  Jaeger  MD  PhD  and  Charles  G  Durbin  Jr  MD 


Introduction 
Tracheal  Tube  Cuffs 
Techniques  for  Lung  Separation 
Double-Lumen  Endotracheal  Tubes 
Endobronchial  Cuffs 
Bronchial  Blockers 

Endotracheal  Tubes  Designed  for  Laser  Surgery 
Endotracheal  Tubes  with  Additional  Ports 
Special  Tubes  and  Devices  to  Aid  with  Intubation 
Head  and  Neck  Surgery 
Summary 

[Respir  Care  1999;44(6):66 1-683]  Key  words:  endotracheal  tube,  endotra- 
cheal tube  cuff,  lung  separation,  artificial  airway,  bronchial  blocker. 


Introduction 

Unique  artificial  airways  and  airway  devices  have  been 
developed  to  solve  a  variety  of  diverse  clinical  problems. 
Since  the  early  1960s  when  plastics  replaced  rubber  in  the 
manufacture  of  endotracheal  tubes  (ETs),  thousands  of 
individual  airways  have  been  designed  and  produced.  Un- 
bridled imagination  and  a  creative  spirit  have  led  to  the 
invention  of  a  variety  of  devices,  many  of  which  have  the 
potential  for  patient  harm.  The  problem  of  tissue  toxicity 
of  the  materials  used  and  the  need  to  connect  to  other 
respiratory  devices  and  anesthesia  devices  necessitated 
some  common  standards  to  which  all  devices  must  con- 
form. These  concerns  of  compatibility  among  the  various 
designs  have  been  minimized  by  development  and  adop- 
tion of  consensus  standards  within  the  American  Society 
for  Testing  and  Materials  (ASTM)  (Internet  address:  http:// 
www.astm.org)  and  the  American  National  Standards  In- 
stitute (ANSI). 

The  original  ASTM  technical  subcommittee  dealing  with 
anesthesia  and  airway  equipment  was  designated  the  Z-79 
Committee.  This  has  now  been  replaced  with  the  F-29 


J  Michael  Jaeger  MD  PhD  and  Charles  G  Durbin  Jr  MD  are  affihated 
with  the  Department  of  Anesthesiology.  University  of  Virginia.  Char- 
lottesville, Virginia. 

Correspondence:  J  Michael  Jaeger  MD  PhD.  Department  of  Anesthesi- 
ology, University  of  Virginia.  Box  10010.  Charlottesville  VA  22906- 
0010.  E-mail;  jmj4w@virginia.edu. 


Committee,  or  Anesthesia  and  Respiratory  Equipment 
Committee,  which  has  numerous  subcommittees  dealing 
with  various  kinds  of  anesthesia  and  respiratory  care  de- 
vices. Most  of  the  subdivisions  are  listed  in  Appendix  1. 
Conformity  to  the  standards  developed  by  the  ASTM  is 
voluntary,  but  most  American  and  international  manufac- 
turers endorse  and  promulgate  these  standards.  The  Amer- 
ican National  Standards  Institute  (ANSI)  (Internet  address: 
http://web.ansi.org)  and  the  International  Standards  Orga- 
nization (ISO)  (Internet  address:  http://www.iso.ch)  dis- 
seminate technical  standards  for  respiratory  care  devices 
(among  other  things),  and  there  is  a  significant  amount  of 
cross-over  between  these  organizations.  Devices  that  con- 
form to  these  standards  are  permitted  to  have  ISO,  ANSI, 
ASTM  or  F-29  imprinted  on  them,  reassuring  the  user  that 
they  have  passed  a  required  series  of  evaluations,  will 
meet  a  set  of  requirements,  and  can  be  connected  to  other 
devices  with  standard  fittings.  Current  individual  standards 
are  available,  for  a  fee,  from  these  organizations.  Collec- 
tions of  these  standards  may  also  be  obtained  by  joining 
the  organization  for  a  yearly  fee.  Documents  can  be  or- 
dered online  and  downloaded  or  faxed  from  the  Internet. 
Many  aspects  of  ETs  are  specified  by  standards:  label- 
ing conventions;  inside  diameter  and  outside  diameter;  dis- 
tance markers  from  the  tip;  material  toxicity  testing  meth- 
od; implant  testing;  packaging  requirements;  angle  and 
direction  of  the  tip  bevel;  size  and  shape  of  the  Murphy 
eye;  presence  and  density  of  radiopaque  marker;  radius  of 
tube  curvature;  reactivity  of  composition  material;  and  char- 


Respiratory  Care  •  June  1999  Vol  44  No  6 


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Special  Purpose  Endotracheal  Tubes 


acteristics  of  the  pilot  balloon  system  are  all  determined  by 
standard.  Standard  sized  slip  fittings  are  required  and  spec- 
ified. Conventional  ETs  must  have  the  inside  and  outside 
diameter  imprinted  on  the  tube,  and  the  cross  section  must 
be  circular,  with  a  uniform  wall  thickness  to  resist  kinking. 
A  bevel  facing  left  must  be  present  at  the  tip,  its  angle 
should  be  between  30  and  45  degrees  from  the  longitudi- 
nal axis.  If  present,  the  Murphy  eye  must  be  at  least  80% 
of  cross  sectional  area  of  the  tube,  and  located  opposite  the 
bevel  of  the  tip.  Tubes  without  a  Murphy  eye  are  called 
Magill-type  tubes  and  can  have  a  higher  risk  of  tube  oc- 
clusion if  the  tip  impinges  against  the  tracheal  or  bronchial 
wall.  However,  secretions  may  be  more  likely  to  build  up 
in  a  tube  with  a  Murphy  eye.  The  tips  of  Murphy-type  and 
Magill-type  tubes  are  shown  in  Figure  1 .  The  Murphy  eye 
should  not  weaken  the  tube,  and  the  tip  and  the  eye  should 
have  no  sharp  points  or  surfaces.  Tubes  should  have  a 
natural  curve  to  facilitate  entry  into  the  larynx.  The  angle 
of  curvature  is  specified  in  the  standards  as  between  12 
and  16  degrees.  The  distance  from  the  tube  tip  must  be 
indicated  in  centimeters.  A  radiopaque  stripe  or  a  tip  marker 
must  be  present,  to  aid  in  locating  the  tube  on  a  radio- 
graph. A  typical,  standard  Murphy  cuffed  ET  is  shown  in 
Figure  2,  illustrating  some  of  these  required  standard  ele- 
ments. Some  of  these  required  standards  are  relevant  to  the 
special  purpose  ETs  discussed  below,  but  many  are  not. 
Most  special  purpose  ETs  are  produced  by  a  single  man- 
ufacturer with  unique  features  protected  by  patent. 

The  most  important  standards  to  which  most  special 
purpose  ETs  conform  are  the  common  connection  to  the 
breathing  circuit  and  the  material  standards.  Tracheal  tubes 
must  have  a  standard  15  mm  slip  fitting  to  connect  to  a 
breathing  circuit  (ISO  standard  5361-1,  ISO  standard 
5366-1);  the  tightness  of  this  fitting  is  also  specified.  If 
equipped  with  a  cuff,  the  pilot  balloon  must  accept  a  stan- 
dard luer  syringe  (ANSI  standard  MD70.1).  The  material 
the  tube  is  made  from  must  be  nonreactive  when  implanted 
in  the  skin  of  an  animal  or  nontoxic  to  tissue-cultured 
cells.  There  are  currently  no  additional  requirements  for 
material  content  of  airway  devices.  Surgical  lasers  are  used 
on  and  around  the  airway,  and  fire  safety  standards  for  the 
materials  used  in  ETs  used  with  lasers  have  recently  been 
developed  (ISO  standard  14408:1998).  Concerns  regard- 
ing latex  allergy  have  led  to  changes  in  ET  materials; 
currently,  most  are  made  of  polyvinyl  chloride  (PVC)  or 
silicone,  and  contain  no  latex.  Specific  components,  such 
as  the  pilot  balloon,  may  contain  latex,  and  specific  man- 
ufacturers should  be  contacted  about  their  individual  de- 
vices if  latex  allergy  is  a  concern. 

Other  components  of  the  standards  described  above  can- 
not easily  be  applied  to  special  purpose  ETs.  This  has  lead 
to  a  large  variety  of  tube  designs  to  solve  the  same  clinical 
problem.  Herein,  several  clinical  problems,  and  some  of 
the  devices  developed  to  solve  them,  are  described.  This 


Fig.  1 .  A:  The  tip  of  a  Murplny  endotracheal  tube,  showing  the 
characteristic  eye.  B:  The  tip  of  a  Magill-type  tube,  without  an  eye. 


662 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Special  Purpose  Endotracheal  Tubes 


Cuff  Pressure  (mm  Hg) 
300 


Fig.  2.  A  standard,  cuffed  Murphy-type  endotracheal  tube,  with 
specified  standard  components  labeled. 


review  also  considers  tracheal  tube  cuffs,  lung  separation, 
hazards  of  laser  surgery,  tubes  with  additional  tracheal 
ports,  tubes  to  facilitate  airway  management  and  intuba- 
tion, and  special  requirements  for  head  and  neck  surgery. 

Tracheal  Tube  Cuffs 

Many  ETs  have  a  cuff  system  that  creates  a  seal  be- 
tween the  ET  and  the  trachea,  preventing  aspiration  from 
the  pharynx  into  the  lungs,  and  allowing  positive  pressure 
ventilation  to  be  applied  through  the  tube.  The  cuff  also 
stabilizes  the  tip  of  the  tube  in  the  center  of  the  trachea, 
minimizing  the  likelihood  of  impingement  on  the  tracheal 


250 


200 


Tube  shown  in  Fig.  4A:  low-volume, 
high-pressure  cuff 


Tube  shown  in  Fig.  4B: 

high-volume,  low- 
pressure  cuff 


10     15     20     30     40     50     60     80 
Cuff  Volume  (mL) 


Fig.  3.  The  pressure-volume  relationship  of  high-compliance  and 
low-compliance  endotracheal  tube  cuffs.  The  hysteresis  effect  of 
inflation  and  deflation  is  related  to  the  plastic  material  used.  Actual 
tracheal  pressures  vary  with  volume,  time,  and  temperature. 


wall.  Tracheal  injury  from  the  ET  or  cuff  is  a  concern  in 
patients  who  require  long-term  intubation.  One  of  the  most 
serious  complications  is  erosion  by  the  tube  through  the 
trachea  and  into  the  esophagus  (tracheoesophageal  fistula) 
or  into  the  innominate  artery  or  other  vessels.  This  is  a  rare 
but  usually  fatal  complication.  Less  severe  but  more  com- 
mon is  the  development  of  tracheal  narrowing  at  the  cuff 
site  following  extubation.  Besides  the  physical  trauma  of 
the  tube  rubbing  against  the  trachea,  tracheal  wall  pres- 
sures from  the  cuff  may  impede  blood  flow  to  the  tracheal 
mucosa.  Capillary  pressure  is  a  function  of  arterial  blood 
pressure  and  is  normally  in  the  range  of  25-35  mm  Hg. 
Lateral  wall  cuff  pressure  higher  than  25-35  mm  Hg  can 
cause  mucosal  ischemia,  leading  to  sloughing  and  tracheal 
denudation.'  During  hypotension,  ischemia  can  result  at 
even  lower  tracheal  wall  pressures. ^  This  initial  mucosal 
ischemic  injury  may  progress  to  cartilage  loss  with  tra- 
cheomalacia or  tracheal  stenosis  occurring  during  the  heal- 
ing process.  Frequent  measurement  and  adjustment  of  cuff 
pressures  to  below  30  cm  HjO,  and  using  the  "just  seal" 
technique  of  cuff  inflation  are  recommended  to  minimize 
cuff-induced  ischemia.  Cuff  material,  shape,  and  compli- 
ance are  important  factors  in  this  problem. 

The  rubber  cuffs  used  before  1960  were  low-compli- 
ance and  needed  very  high  pressures  to  achieve  a  tracheal 
seal.  The  low  compliance,  tissue  toxicity,  and  rigidity  of 
the  tubes  often  caused  tracheal  damage.  PVC  ETs  and 
cuffs  replaced  rubber,  and  the  incidence  of  tracheal  (and 
laryngeal)  damage  declined.  Some  of  these  plastic  cuffs 
are  low-compliance,  with  a  small  profile.  These  cuffs  per- 
mit easier  intubation  and  produce  a  high-pressure  tracheal 
seal  to  prevent  aspiration  and  permit  high-pressure  me- 
chanical ventilation.  Low-compliance  cuffs  increase  pres- 
sure on  the  trachea  and  increase  the  risk  of  ischemic  in- 


Respiratory  Care  •  June  1999  Vol  44  No  6 


663 


Special  Purpose  Endotracheal  Tubes 


Fig.  4.  A:  Endotracheal  tube  with  low-volume,  high-pressure  cuff.  B:  Endotracheal  tube  with  high-volume,  low-pressure  cuff. 


jury.  The  tracheal  cuff  pressure  curves  shown  in  Figure  3 
were  generated  using  a  low-volume,  high-pressure  cuff  ET 
similar  to  the  one  shown  in  Figure  4A,  and  a  high-volume 
low-pressure  cuff,  as  shown  in  Figure  4B.  The  data  in 
Figure  3  were  obtained  by  step-wise  inflation  of  the  cuff 
and  immediate  measurement  of  the  cuff  pressure.  Once  the 
cuff  was  fully  (over)  inflated,  the  deflation  pressure  curve 
was  recorded.  These  pressures  were  measured  at  the  pilot 
balloon  connector,  at  room  temperature  (23°C),  not  in  the 
trachea. 

The  technique  of  inflating  the  cuff  only  enough  to  "just 
seal"  was  developed  to  help  minimize  the  tracheal  risk. 
Manometers  to  monitor  and  adjust  the  cuff  pressure  to  25 
cm  HjO  became  the  standard  of  care  in  patients  with  pro- 
longed intubation.  The  impact  on  the  development  of  tra- 
cheal injury  from  careful  cuff  pressure  management  has 
not  been  established  in  controlled  studies.  Larger,  high- 
compliance  cuffs  were  developed  to  spread  the  cuff  con- 
tact point  over  a  larger  area  so  as  to  minimize  the  pressure 
at  any  one  point.  ETs  with  larger  cuffs  are  more  difficult 
to  insert  through  the  larynx,  since  they  are  bulkier  and  are 
less  effective  at  preventing  aspiration  around  the  cuff.' 


The  use  of  high-pressure,  low-compliance  cuffs  during 
surgery  is  associated  with  development  of  extremely  high 
cuff  pressures  because  of  the  diffusion  of  nitrous  oxide 
into  the  cuff.-*  The  magnitude  of  this  problem  is  related  to 
the  concentration  of  nitrous  oxide  used  and  the  duration  of 
the  anesthetic.  The  true  tracheal  pressure  is  not  easy  to 
estimate  when  these  cuffs  are  used,  since  most  of  the  cuff 
pressure  is  dissipated  in  expanding  the  cuff  itself.  How- 
ever, the  cuff  contact  points  in  the  trachea  are  small  in  area 
and  often  exceed  mucosal  perfusion  pressure.  Most  of  the 
concerns  about  aspiration  risk  and  cuff  pressures  relate  to 
long-term  intubation.  Special  cuffs  and  tube  designs  have 
been  developed  to  reduce  the  risk  of  aspiration  while  also 
maintaining  a  cuff  seal. 

High-volume,  high-compliance,  floppy  cuffs  form  a  seal 
by  contacting  and  conforming  over  a  large  area  of  the 
tracheal  wall.  Cuff  pressure  in  these  tubes  reflects  the 
lateral  wall  tracheal  pressure.''  A  high-volume,  high-com- 
pliance cuff  is  shown  in  Figure  4B,  and  its  compliance 
curve  is  shown  in  Figure  3.  The  potential  ischemic  area  is 
larger  than  with  low-compliance  cuffs.  A  very  large  cuff 
will  have  folds  that  can  allow  aspiration  around  the  cuff.'' 


664 


Respiratory  Care  •  June  1 999  Vol  44  No  6 


Special  Purpose  Endotracheal  Tubes 


Self  Inflating  Cuff 


Fig.  5.  Bivona  Fome-Cuf.  The  cuff  must  be  aspirated  flat  for  in- 
sertion and  Vnen  opened  to  air  in  order  to  self-inflate.  (Photo  cour- 
tesy of  Bivona  Medical  Technologies.) 


Fig.  6.  With  the  Bivona  Fome-Cuf  endotracheal  tube,  airway  pres- 
sure from  the  mechanical  ventilator  is  delivered  to  the  foam  cuff, 
increasing  cuff  pressure  and  maintaining  a  seal  during  inhalation. 
(Photo  courtesy  of  Bivona  Medical  Technologies.) 


It  appears  that  there  is  a  reduction  of  tracheal  cuff  com- 
phcations  with  large-volume,  high-compliance  cuffs.  How- 
ever, there  is  no  guarantee  that  cuff  pressure  will  remain 
low,  and,  even  when  properly  used,  these  cuffs  do  not 
totally  eliminate  tracheal  injury. 

Another  solution  for  prevention  of  high  tracheal  wall 
pressures  is  using  self-inflating  foam  material  to  fill  the 
cuff.  A  foam-filled  cuff  must  be  actively  deflated  prior  to 
insertion,  then  allowed  to  passively  fill  by  opening  the  cuff 
pilot  tube  to  air.  This  type  of  cuff,  the  Fome-Cuf  (Bivona 
Medical  Technologies.  Gary.  Indiana),  is  shown  in  Figure 
5.  The  seal  formed  by  the  foam-filled  cuff  is  low-pressure 
and  spread  over  a  large  surface  area  of  the  trachea.  In  order 
to  provide  positive  pressure  ventilation  without  a  ventila- 
tion leak,  the  cuff  pressure  can  be  raised  to  airway  pressure 
by  connecting  the  pilot  lumen  to  the  airway.  With  the 
setup  illustrated  in  Figure  6,  during  inspiration  the  cuff 
pressure  is  increased  to  ventilation  pressure,  reducing  the 
leak.  There  is  no  check  valve  in  the  pilot  tube,  and  if  high 
cuff  pressures  are  constantly  needed,  a  stopcock  or  clamp 


Fig.  7.  Lantz  cuff  pressure-regulating  system. 


can  be  added,  though  this  overcomes  the  low-pressure  seal 
advantage  of  this  cuff  design. 

Figure  7  shows  an  automatic  tracheal  cuff  pressure- 
regulating  system  (the  Lantz  system),  which  connects  a 
high-compliance  external  cuff  to  the  tracheal  seal  cuff. 
When  pressures  in  the  tracheal  cuff  exceed  30  mm  Hg,  air 
is  slowly  bled  into  the  pilot  balloon.  On  initial  rapid  in- 
flation, the  tracheal  cuff  is  inflated  to  a  high  pressure. 
During  successive  positive  pressure  breaths,  air  redistrib- 
utes from  the  tracheal  cuff  to  the  pilot  balloon,  reducing 
tracheal  cuff  pressure  to  23-33  mm  Hg.  Since  gas  flow  is 
one-way,  a  cuff  leak  often  develops,  and  cuff  reinflation  is 
needed  to  achieve  a  seal.  If  very  high  pressures  are  needed, 
the  pilot  balloon  can  be  overintlated  to  seal  in  the  protec- 
tive outer  sheath,  and  the  system  becomes  a  high-volume 
unregulated  system.^ 

Techniques  for  Lung  Separation 

Complicated  surgery  of  structures  within  the  thorax  (eg, 
lungs,  esophagus,  sympathetic  nervous  system  ganglion, 
thoracic  veilebrae,  thoracic  lymphatic  system,  and  the  tho- 


Respiratory  Care  •  June  1 999  Vol  44  No  6 


665 


Special  Purpose  Endotracheal  Tubes 


racic  portions  of  the  great  blood  vessels),  is  facilitated  by 
the  technique  of  one-lung  ventilation.  One-lung  ventilation 
is  a  process  that  requires  a  specialized  ET  or  a  combina- 
tion of  a  standard  single  ET  and  an  airway-blocking  device 
to  physically  isolate  ventilation  to  the  right  or  left  lung. 
Generally,  one  lung  is  isolated  and  collapsed  while  the 
other  lung  is  ventilated.  This  approach  produces  excellent 
visualization  of  the  thoracic  structures  and  markedly  re- 
duces movement  within  the  exposed  hemithorax.  During 
partial  or  total  pneumonectomy,  deflation  of  the  resected 
lung  allows  careful,  deliberate  dissection  and  control  of 
vessels  and  bronchi  prior  to  clamping  the  specimen.  Dur- 
ing vascular  procedures  such  as  thoracic  aneurysmectomy, 
deflation  of  the  lung  protects  it  from  severe  bleeding  and 
contusion  that  can  occur  because  of  systemic  anticoagu- 
lation. At  the  conclusion  of  surgery,  the  collapsed  lung  is 
re-expanded  and  two-lung  ventilation  is  re-established. 

In  addition  to  surgical  indications,  there  are  a  number  of 
special  conditions  that  can  occur  and  can  benefit  from  lung 
isolation.  One  classical  indication  for  lung  isolation  is  mas- 
sive hemoptysis,  which  can  occur  from  a  ruptured  pulmo- 
nary artery,  arteriovenous  malformation,  endobronchial 
carcinoma,  or  pulmonary  embolus.  Necrotizing  pneumo- 
nia or  lung  abscess  might  also  require  lung  isolation.  In 
these  situations,  isolation  of  the  uninvolved  lung  can  help 
prevent  contamination  from  the  involved  lung  by  infected 
secretions  or  blood  that  would  otherwise  spread  infection 
to  and  worsen  ventilation  and  perfusion  mismatching  in 
the  uninvolved  lung.  This  preservation  of  the  normal  lung 
becomes  essential  if  gas  exchange  is  severely  compro- 
mised in  the  diseased  lung. 

Lung  separation  can  be  used  to  apply  different  forms  of 
mechanical  ventilation  in  patients  with  bronchopleural  fis- 
tulas, pulmonary  parenchymal  lacerations,  or  those  with 
lungs  of  markedly  different  compliance  or  airway  resis- 
tance, such  as  following  single  lung  transplantation.  Any 
combination  of  mechanical  ventilation  techniques  can  be 
used  to  ventilate  or  "rest"  either  lung  independently.  Lung 
separation  is  also  used  to  perform  bronchoalveolar  lavage, 
either  to  wash  out  blood  or  infected  secretions  from  the 
affected  lung,  or  to  sequentially  remove  the  thick,  tena- 
cious secretions  from  each  lung  of  patients  with  pulmo- 
nary alveolar  proteinosis. 

The  earliest  approach  to  lung  isolation  was  developed  in 
the  1930s,  and  utilized  "bronchial  blockers"  fashioned  from 
bundles  of  gauze  or  balloon-tipped  catheters  placed  in  the 
bronchus  through  a  rigid  bronchoscope.  Variations  of  these 
devices  are  still  used  today  in  special  situations,  and  will 
be  discussed  below. 

Double-Lumen  Endotracheal  Tubes 

The  double-lumen  endotracheal  tube  (DLET)  is  the  most 
common  device  used  to  allow  separate  ventilation  of  the 


Fig.  8.  Double-lumen  endotracheal  tube.  (Photograph  courtesy  of 
Malllnckrodt  Inc.) 


lungs.  One  such  tube  is  shown  in  Figure  8.  It  is  simply  two 
long,  cuffed  ETs  fused  together  so  as  to  permit  one  lumen 
and  cuff  to  reside  in  a  pulmonary  bronchus  and  the  other 
to  remain  more  proximal  in  the  trachea.  With  each  lumen 
independently  connected  to  a  ventilator  or  both  lumens 
united  via  a  bridge  connector  (Cobb  adapter.  Fig.  9)  at- 
tached to  a  single  ventilator,  gas  flow  into  each  lung  can  be 
controlled.  As  an  example  of  its  application,  consider  the 
patient  with  a  right  lung  mass  undergoing  surgical  resec- 
tion. The  patient  is  placed  under  general  anesthesia  and  the 
trachea  is  intubated  with  a  left-sided  DLET.  The  DLET  is 
inserted  to  a  depth  that  places  the  endobronchial  tube  with 
its  small  cuff  within  the  left  main  bronchus.  The  tracheal 
lumen  opens  more  proximally  on  the  shaft  of  the  DLET, 
above  the  carina.  Proximal  to  the  tracheal  lumen  opening, 
a  larger  cuff  completely  envelops  the  device  such  that, 
when  inflated,  it  forms  an  air-tight  seal  within  the  trachea, 
like  a  standard  ET.  With  the  small  endobronchial  cuff 
inflated,  the  left  lung  becomes  isolated  from  the  right  lung. 
The  only  way  for  air  to  flow  into  the  right  lung  is  via  the 
tracheal  portion  of  the  DLET,  and  the  only  way  for  air  to 
flow  into  the  left  lung  is  via  the  endobronchial  portion  of 


666 


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Special  Purpose  Endotracheal  Tubes 


Fig.  9.  A  Cobb  connector  (adapter)  is  used  to  connect  both  lumens 
of  a  double-lumen  endotracheal  tube  to  one  ventilator. 


the  DLET.  The  endobronchial  cuff  effectively  seals  off  the 
left  main  bronchus  from  the  trachea.  To  collapse  the  right 
lung  and  provide  a  motionless  operative  field  for  the  sur- 
geon, the  lumen  of  the  tracheal  portion  of  the  DLET  bridge 
connector  is  occluded  with  a  hose  clamp,  and  the  air  within 
the  right  lung  is  allowed  to  egress  when  the  thorax  is 
entered.  With  the  right  side  of  the  DLET  clamped,  air  from 
the  mechanical  ventilator  on  the  anesthesia  machine  is 
directed  solely  to  the  left  endobronchial  side  of  the  DLET. 
This  establishes  one-lung  ventilation,  which,  as  long  as 
acceptable  gas  exchange  continues,  can  be  used  for  pro- 
longed periods  of  time.  At  the  conclusion  of  the  surgery, 
the  remainder  of  the  right  lung  is  gently  reinflated  by 
reattaching  the  tracheal  side  of  the  DLET  and  releasing  the 
clamp,  thus  reestablishing  bilateral  air  flow  to  the  lungs. 
There  are  several  versions  of  the  DLET  on  the  market. 
The  most  popular  is  the  Robertshaw-like  design  (no  cari- 
nal  hook),  which  is  constructed  of  the  same  nonreactive 
materials  as  previously  described  for  the  single-lumen  ET. 
DLETs  are  available  in  a  variety  of  sizes:  28  Fr,  35  Fr,  37 
Fr,  39  Fr,  and  41  Fr,  are  about  42  cm  long,  and  are  pro- 
duced by  a  variety  of  different  manufacturers.  The  choice 
of  size  depends  on  the  patient's  anatomy  and  is  crucial.  If 
the  DLET  is  too  large,  it  will  not  fit  into  the  main  bronchus 
and  is  difficult  to  pass  through  the  glottis.  If  the  DLET  is 
too  small,  it  will  require  a  high  cuff  pressure  to  obtain  a 
seal,  resulting  in  inappropriately  high  pressure  against  the 
bronchial  mucosa.  Also,  the  smaller  the  DLET,  the  higher 
the  resistance  to  air  flow.  For  example,  the  air  flow  resis- 


tance of  the  endobronchial  side  of  a  39  Fr  DLET  is  equiv- 
alent to  a  7.0  mm  inside  diameter  single-lumen  ET,  while 
a  35  Fr  DLET  is  equivalent  to  a  6.0  inside  diameter  ET.  Of 
note,  the  lumens  of  a  DLET  are  not  perfectly  round  (as 
they  are  in  a  single-lumen  ET).  The  tracheal  lumen  is 
D-shaped,  with  the  flat  portion  of  the  lumen  abutting  the 
shared  wall  with  the  endobronchial  lumen.  This  imposes 
significant  limitations  on  the  passage  of  suction  catheters 
and  fiberoptic  bronchoscopes  (FOBs).  Some  versions  of 
the  DLET  are  constructed  of  red  rubber  with  latex  cuffs,  to 
allow  re-sterilization  for  multiple  use.  These  are  less  com- 
monly used  because  of  problems  of  uneven  cuff  inflation 
after  multiple  uses,  tissue  toxicity,  stiffness,  and  the  uni- 
formly higher  cuff  pressures  required  for  adequate  seal.** 
Bronchial  mucosal  damage  is  more  common  with  the  use 
of  red  rubber  DLETs. '^  These  rubber  DLETs  contain  latex, 
and,  of  course,  should  not  be  used  in  patients  with  latex 
allergy. 

The  Carlens  DLET  (a  variation  of  the  Robertshaw  style) 
incorporates  a  special  carinal  hook  midway  between  the 
endobronchial  cuff  and  the  lumen  of  the  tracheal  side.  The 
hook  is  designed  to  straddle  the  carina  and  prevent  a  left- 
sided  DLET  from  being  inserted  too  far,  as  well  as  to 
provide  stabilization  of  the  distal  portion  of  the  DLET.  A 
right-sided  version,  the  White  DLET,  was  also  developed. 
However,  neither  of  these  types  (Fig.  10)  are  currently 
popular  because  the  carinal  hook  ( 1 )  increases  the  diffi- 
culty of  passing  the  device  through  the  glottis,  (2)  can 
cause  malpositioning  in  the  bronchus,  (3)  can  cause  trauma 
to  the  airway  during  insertion,  and  (4)  has  been  known  to 
separate  from  the  body  of  the  DLET  in  situ.  They  are, 
however,  easier  to  position  correctly  and  are  less  likely  to 
become  displaced  during  use. 

All  disposable  and  reusable  DLETs  are  marked  (in  cen- 
timeters) along  their  length  to  aid  in  correct  placement.  As 
a  first  approximation,  for  both  males  and  females  1 70  cm 
tall,  the  average  depth  of  insertion  is  29  cm  at  the  teeth.'" 
For  each  10  cm  increase  or  decrease  in  height,  the  place- 
ment depth  will  be  increased  or  decreased  approximately  1 
cm.  To  aid  in  visualization  on  roentgenograms,  the  DLET 
has  one  radiopaque  ring  marker  around  the  endobronchial 
lumen  lip,  another  one  proximal  to  the  cuff,  and  a  ra- 
diopaque line  running  the  length  of  the  tube. 

Endobronchial  Cuffs 

Both  the  small-volume,  blue  (by  convention)  endobron- 
chial cuff,  and  the  larger,  clear  tracheal  cuff  are  inflated  by 
their  corresponding  color-coded  inflation  valves,  which 
are  incorporated  into  the  walls  of  the  DLET  in  the  same 
way  as  in  single-lumen  ETs.  The  endobronchial  cuff  de- 
sign differs  between  right-sided  and  left-sided  DLET,  and 
between  manufacturers.  Most  left-sided  DLET  endobron- 
chial cuffs  are  similar  and  consist  of  a  spheroid  or  ellip- 


Respiratory  Care  •  June  1999  Vol  44  No  6 


667 


Special  Purpose  Endotracheal  Tubes 


Fig.  10  A:  White  double-lumen  endotracheal  tube,  with  carinal 
hook  in  position. 


Fig.  10  B:  Carlen  double-lumen  endotracheal  tube,  with  carinal 
hook  in  position. 

tical  cuff  approximately  1  cm  proximal  to  the  end  of  the 
tube.  Right-sided  DLET  designs  have  incorporated  several 
approaches  to  accommodate  the  short  right  main  bronchus 
(length  averages  14  mm  in  adult  females  and  18  mm  in 
adult  iTiales),  and  the  orifice  of  the  right  upper  lobe  bron- 
chus. Two  of  these  design  approaches  are  shown  in  Figure 
1 1 .  The  right  BronchoCath  (Mallinckrodt  Inc.  Pleasanton, 


Fig.  11 .  Two  types  of  right-sided  double-lumen  endotracheal  tubes, 
showing  different  cuff  designs  to  accommodate  the  take  off  of  the 
right  upper  lobe  bronchus. 


California)  utilizes  an  elongated,  S-shaped  endobronchial 
cuff  attached  at  an  acute  angle  to  allow  the  addition  of  a 
large  Murphy  eye  to  oppose  the  orifice  of  the  right  upper 
lobe  bronchus.  The  right-sided  Sher-i-Bronch  (Kendall 
Healthcare,  Mansfield,  Massachusetts)  incorporates  two 
small,  round  endobronchial  cuffs  that  straddle  a  through- 
and-through  slit-like  opening  in  the  distal  wall  of  the  en- 
dobronchial tube.  Riisch  Inc  (Duluth,  Georgia)  manufac- 
tures a  tube  similar  to  Mallinckrodt's,  except  that  instead 
of  an  elongated,  angled  "wedding  band"  type  cuff,  it  uses 
a  "signet  ring"  shaped  cuff  that  becomes  extremely  narrow 
on  the  side  opposite  the  orifice  of  the  right  upper  lobe 
bronchus,  to  accommodate  a  Murphy  eye.  The  Robert- 
shaw  design  has  a  hole  through  the  lateral  aspect  of  the 
cuff.  The  crucial  feature  of  all  cuff  designs  is  to  allow 
sealing  and  isolation  of  the  right  or  left  bronchus  without 
occluding  any  of  the  upper  lobe  bronchi.  In  actual  use.  the 
right  upper  lobe  is  often  partially  or  completely  occluded 
and  poorly  ventilated.  Most  authors  suggest  using  only  left 
sided  DLETs  unless  left  mainstem  intubation  is  contrain- 
dicated. 

Most  DLETs  come  disassembled  in  multiple  sterile  pack- 
ages and  must  be  constructed  and  tested  prior  to  use.  First, 
the  components  are  removed  from  their  packages  and  placed 
on  a  clean  surface  (the  large  package  containing  the  en- 
dobronchial tube  works  best).  The  Cobb  adapter  is  assem- 
bled with  care  taken  to  keep  individual  tube  adapters  in 
register  to  ease  the  final  assembly  after  intubation.  The 
endobronchial  and  tracheal  cuff  assemblies  are  tested  for 


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Special  Purpose  Endotracheal  Tubes 


leaks  and  symmetry  after  inflation.  The  DLET  is  inserted 
with  the  cuffs  deflated.  The  stylet,  a  stiff  wire  that  runs  the 
length  of  the  endobronchial  side  of  the  DLET,  can  be 
lubricated  lightly  with  a  nonpetroleum-based  lubricant  to 
allow  easy  removal.  The  tip  of  the  DLET  can  be  bent  or 
straightened  as  deemed  necessary  by  the  individual  per- 
forming intubation. 

All  DLETs  are  relatively  stiff  and  are  bulky  compared 
to  their  single  lumen  counterparts.  Therefore,  their  intro- 
duction through  the  glottis  is  considerably  more  difficult, 
and  great  care  must  be  taken  to  avoid  harming  the  patient 
or  damaging  the  DLET  during  intubation.  A  typical  DLET 
intubation  would  be  performed  as  follows.  With  the  pa- 
tient's head  and  neck  in  the  "sniffing"  position,  the  patient 
breathes  100%  oxygen  for  several  minutes.  A  sedative- 
hypnotic  drug  is  given  to  induce  a  state  of  deep  anesthesia, 
and  narcotics  or  intravenous  lidocaine  can  be  added  to 
suppress  laryngeal  reflexes.  A  muscle  relaxant  is  admin- 
istered to  facilitate  laryngoscopy.  Laryngoscopy  is  per- 
formed when  all  medications  have  reached  their  peak  ef- 
fect. The  natural  curvature  of  the  endobronchial  tip 
facilitates  placement  in  the  right  or  left  main  bronchus  as 
the  DLET  is  advanced.  It  interferes  with  glottic  passage 
and  necessitates  a  series  of  rotational  movements.  With  the 
glottic  opening  in  view,  the  tip  of  the  endobronchial  tube 
is  inserted  between  the  open  vocal  cords,  with  the  pre- 
formed curvature  directed  anteriorly.  As  the  endobronchial 
cuff  passes  through  the  vocal  cords,  the  DLET  is  rotated 
approximately  90-100  degrees  to  align  the  curved  tip  with 
the  orientation  of  the  appropriate  main  bronchus.  At  this 
point,  some  intubators  would  remove  the  stylet  to  allow 
the  tip  more  flexibility  and  presumably  decrease  the  risk  of 
damage  to  the  trachea  and  bronchus.  Note,  however,  that 
a  recent  controlled  trial  found  no  significant  increase  in  the 
incidence  of  tracheal  damage  by  leaving  the  stylet  in  until 
the  DLET  was  in  final  position."  The  DLET  with  the 
stylet  in  place  is  carefully  advanced  until  resistance  is  felt, 
indicating  that  it  is  seated  in  the  bronchus.  The  tracheal 
cuff  is  inflated  to  form  a  seal,  and  the  Cobb  adapter  is 
inserted  into  the  proximal  lumens.  As  the  lungs  are  in- 
flated, the  chest  is  assessed  (visually,  by  auscultation,  and 
by  measurement  of  exhaled  carbon  dioxide)  to  confirm 
endotracheal  placement. 

The  final  step  is  the  fine  adjustment  of  the  DLET  to 
enable  isolation  of  the  lungs  without  unintentional  ob- 
struction of  the  airways.  The  endobronchial  cuff  is  inflated 
and  the  chest  is  carefully  auscultated  bilaterally  while  the 
tracheal  and  endobronchial  lumens  are  sequentially  oc- 
cluded with  a  hose  clamp.  When  the  DLET  is  correctly 
placed,  a  distinct  separation  of  breath  sounds  should  be 
readily  identifiable  with  clamping  and  unclamping  of  each 
lumen.  Nonetheless,  one  study  found  that  when  strict  cri- 
teria were  applied,  FOB  examination  indicated  that  be- 
tween 38%  and  83%  of  DLETs  are  malpositioned  when 


Fig.  12.  Note  that  the  bronchial  balloon  is  protruding  slightly  at  the 
carina. 

placed  by  auscultatory  means  alone.'-  Final  determination 
of  correct  DLET  placement  must  be  made  via  FOB,  so  a 
FOB  must  be  readily  accessible.  Because  movement  of  the 
DLET  is  possible  whenever  movement  of  the  patient  oc- 
curs, bronchoscopy  should  be  repeated  after  any  patient 
position  change.  Correct  DLET  placement  is  confirmed 
when  the  blue  bronchial  cuff  is  seen  protruding  slightly  at 
the  carina,  as  shown  in  Figure  12. 

Bronchial  Blockers 

Although  DLETs  are  the  most  common  devices  used  to 
separate  the  lungs,  other  devices  and  approaches  can  be 
more  efficient  in  certain  circumstances.  One  such  device  is 
the  single-use  Inoue  Univent  tube  (Fuji  Systems  Corpora- 
tion, Tokyo,  Japan)  shown  in  Figure  13.  It  consists  of  a 
large,  single-lumen  silicone  rubber  ET  with  an  extra  chan- 
nel fused  to  its  entire  length.'^  This  channel  contains  a 
long,  thin,  cuffed  hollow  rod  that  can  be  advanced  into  the 
right  or  left  main  bronchus,  then  inflated  to  block  the 
airway  (Fig.  14).  The  bronchial  blocker  can  be  connected 
to  suction  (to  evacuate  air,  blood,  or  secretions  from  the 
occluded  lung),  connected  to  a  high-frequency  jet  ventila- 
tor, or  it  can  be  capped.  It  is  more  difficult  to  blindly  place 
the  bronchial  blocker  in  the  correct  bronchus,  especially 
the  left  bronchus,  than  it  is  to  place  a  standard  DLET. 
Therefore,  a  FOB  is  essential.  The  Univent  tube  is  con- 
structed with  the  bronchial  blocker  on  the  right  side  and 
tends  to  favor  entry  into  the  right  bronchus  when  the  blocker 
is  advanced.  A  left-sided  placement  is  accomplished  by 
rotating  the  Univent  tube  about  180  degrees  while  advanc- 


Respiratory  Care  •  June  1999  Vol  44  No  6 


669 


Special  Purpose  Endotracheal  Tubes 


TrachMl  raot 
Batioon 


Tmchwrf 
Cuff 


Bronchial  BtocI 
Balloon 


Fig.  13.  The  Univent  tube  has  a  self-contained  bronchial  blocker 
that  can  be  advanced  into  either  bronchus. 


ing  the  blocker.  The  blocker  can  also  be  guided  with  the 
tip  of  the  FOB.  It  is  recommended  that  the  blocker  be 
inserted  well  into  the  bronchus  and  not  inflated  until  the 
patient  is  placed  in  the  optimal  surgical  position.  Once  the 
patient  is  in  final  position,  the  endobronchial  blocker  cuff 
can  be  pulled  back  out  of  the  bronchus  to  its  optimum 
position  and  inflated  under  direct  vision.  It  can  be  posi- 
tioned with  the  cuff  barely  visible  at  the  carina.  However, 
the  blocker  has  a  tendency  to  slip  out  of  the  bronchus 
easily,  so  it  is  recommended  that  the  blocker  be  inserted 
deeper  into  the  bronchus,  such  that  when  the  cuff  is  in- 
flated it  partially  occludes  the  lumen  of  the  right  or  left 
upper  lobe  bronchus.  This  is  less  of  a  problem  than  with  a 
DLET,  since  ventilation  of  the  lung  with  the  blocker  is  not 
an  issue.  This  will  assist  in  maintaining  position  during 
surgical  manipulation  of  the  lung.  Of  course  this  will  also 
prevent  air  or  secretions  from  leaving  the  upper  lobe.  Dur- 
ing lung  surgery,  suspension  of  mechanical  ventilation  just 
before  the  pleural  space  is  entered,  and  inflation  of  the 


Fig.  14.  Close  up  of  the  bronchial  blocker  exiting  the  Univent  tube. 


bronchial  blocker  results  in  the  desired  lung  collapse.  The 
Univent  tube  comes  in  sizes  ranging  from  3.5  mm  to  9.0 
mm  inside  diameter,  with  corresponding  outside  diameters 
ranging  from  8.0  to  14.0  mm.  Its  greatest  advantage  over 
a  DLET  is  that  it  is  easier  to  insert  into  a  difficult  airway. 
Once  lung  separation  is  no  longer  required,  the  blocker  can 
be  retracted  into  the  channel  and  the  ET  used  in  the  stan- 
dard fashion  without  reintubation. 

Latex  Foley  catheters  and  Fogarty  embolectomy  cathe- 
ters have  also  been  used  as  bronchial  blockers,  in  conjunc- 
tion with  a  standard  cuffed  ET  or  tracheostomy  appliance. 
These  catheters  were  not  designed  for  use  as  endobron- 
chial blockers  and  therefore  must  be  used  very  cautiously 
for  this  purpose.  The  Fogarty  balloon  catheter  is  probably 
the  easiest  to  use,  and  is  readily  available  in  most  hospi- 
tals. Their  wide  range  of  balloon  sizes  (diameter  when 
fully  deflated,  3.9  Fr,  4.7  Fr,  5.7  Fr,  14  Fr.  and  22  Fr) 
allows  the  use  of  Fogarty  catheters  as  endobronchial  block- 
ers in  both  pediatric  and  adult  lungs.'^  '-"^  These  catheters 
come  with  a  wire  stylet  that  allows  the  tip  to  be  pre-formed 
to  facilitate  insertion  into  the  bronchus.  Once  in  place,  the 
stylet  is  removed  in  order  to  inflate  the  balloon  with  an 
air-filled  syringe.  A  sliding  lock  on  the  syringe  Luer-Lok 
(Becton  Dickinson  and  Company,  Franklin  Lakes,  New 
Jersey)  secures  the  inflated  balloon.  The  main  disadvan- 
tage of  using  these  substitute  endobronchial  blockers  is 
that  the  balloons  are  high  pressure  and  low-volume,  and 
therefore  exert  relatively  high  pressure  on  the  bronchial 
mucosa,  which  can  lead  to  necrosis  and  stenosis.  We  rec- 
ommend that  their  duration  of  use  be  limited  to  no  more 
than  2  hours.  In  addition,  the  balloons  are  fairly  short, 
often  grossly  asymmetrical,  and  easily  slip  out  of  the  bron- 
chus. Fogarty  catheters  are  extremely  long  (40-80  cm) 
and  stiff.  Because  of  the  risk  of  perforating  a  small  bron- 


670 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Special  Purpose  Endotracheal  Tubes 


chus,  these  catheters  should  never  be  inserted  very  far  into 
the  trachea  without  direct  visuaHzation.  Finally,  the  only 
way  to  evacuate  air  or  secretions  from  the  occluded  lung  is 
to  deflate  the  balloon.  Despite  these  drawbacks,  these  cath- 
eters have  proven  useful  in  difficult  airways  and  special 
circumstances.  One  approach  to  placing  these  catheters  is 
to  intubate  the  trachea  with  a  standard  ET  and  then  pass  a 
Fogarty  catheter  through  the  port  of  a  FOB  ET  adapter  and 
into  the  trachea.  Alternatively,  the  trachea  can  be  intubated 
first  with  the  thin  Fogarty  catheter  and  then  a  standard  ET 
is  placed  next  to  the  catheter.  A  FOB  inserted  through  the 
ET  is  used  to  visualize  the  target  bronchus  and  guide  the 
catheter  into  position.  Once  the  blocker  is  no  longer  needed, 
it  can  be  withdrawn  past  the  ET  without  loosing  control  of 
the  airway. 

Fiberoptic  bronchoscopy  allows  for  unequivocal  deter- 
mination of  correct  DLET  or  bronchial  blocker  placement, 
fine  adjustments  to  the  depth  of  insertion  and  position  of 
the  endobronchial  cuff,  examination  of  the  airways  for 
damage  during  insertion,  and  selective  bronchial  toilet. 
The  size  of  the  FOB  is  critical.  It  is  easy  to  damage  the 
scope  if  a  large  sized  FOB  is  forced  or,  more  frequently,  if 
the  scope  becomes  lodged  in  the  tube  during  attempted 
withdrawal.  In  general,  a  pediatric  FOB  (outside  diameter 
3.6-4.2  mm)  fits  down  all  sizes  of  DLET,  while  a  FOB  of 
intermediate  size  (4.9  mm)  only  fits  through  a  39  Fr  or  41 
Fr  DLET.  The  FOB  should  be  properly  prepared  before 
insertion  into  the  DLET.  Applying  a  thin  layer  of  water- 
based  sterile  lubricant  to  the  length  of  the  FOB  lessens  the 
chance  of  its  plastic  coating  adhering  to  the  walls  of  the 
DLET.  Warming  the  FOB  in  body-temperature  water  prior 
to  insertion,  and  application  of  a  commercial  lens-anti-fog 
preparation,  will  greatly  enhance  visualization.  The  lubri- 
cated FOB  is  gently  inserted  through  a  bronchoscopy  sleeve 
at  the  top  of  the  ET  elbow  adapter  (usually  included  with 
the  disposable  DLET)  on  the  tracheal  side  of  the  DLET.  It 
should  be  gently  advanced  while  observing  progress 
through  the  eyepiece.  This  approach  allows  easy  naviga- 
tion through  the  junction  of  endobronchial  and  tracheal 
tubes  and,  more  importantly,  negotiation  of  the  tip  past 
any  mucous  or  blood  adhering  to  the  walls  of  the  DLET. 
Once  the  FOB  exits  the  lumen  of  the  DLET,  the  carina  is 
identified  and  the  presence  of  the  endobronchial  portion  of 
the  DLET  in  the  appropriate  bronchus  is  established.  In 
most  situations,  the  DLET  should  be  advanced  or  retracted 
until  just  a  "lip"  of  the  blue  endobronchial  cuff  is  visible 
at  the  carina  when  the  cuff  is  inflated  adequately  (see  Fig. 
12).  This  should  place  the  cuff  at  a  short  distance  within 
the  bronchus,  which  will  not  obstruct  either  the  left  upper 
lobe  bronchus  (in  the  case  of  a  left-sided  DLET)  or  the 
right  upper  lobe  bronchus  (in  the  case  of  a  right-sided 
DLET).  However,  the  margin  of  error  is  much  smaller  in 
the  case  of  a  right-sided  DLET  because  the  right  main 
bronchus  is  so  short."'  Therefore,  FOB  examination  of  the 


endobronchial  lumen  is  recommended,  with  particular  at- 
tention to  viewing  the  orifice  of  the  right  upper  lobe  bron- 
chus through  the  Murphy  eye  of  the  right-sided  DLET. 
This  is  more  difficult  than  it  may  appear  at  first.  It  can  be 
useful  to  carefully  direct  the  tip  of  the  FOB  toward  the 
Murphy  eye  with  the  intent  of  searching  for  the  dark  shadow 
of  the  orifice  to  the  right  upper  lobe  bronchus.  Sometimes 
the  orifice  can  be  readily  seen  through  the  clear  blue  wall 
of  the  tube  or,  if  not,  then  after  slow  rotation  of  the  DLET 
while  looking  through  the  Murphy  eye.  Since,  in  the  ma- 
jority of  cases,  the  orifice  lies  between  the  12  o'clock  and 
3  o'clock  positions,  initial  rotation  counterclockwise  is 
used.  Ultimately,  it  is  only  important  that  the  cuff  does  not 
occlude  the  right  upper  lobe  bronchus.  It  is  not  necessary 
to  juxtapose  the  Murphy  eye  with  the  orifice. 

The  final  step  is  to  secure  the  DLET  or  Univent  tube 
(using  twill  tape  or  adhesive  tape)  to  prevent  accidental 
dislodgment.  It  is  essential  to  realize  that  any  attempt  to 
secure  and  stabilize  these  rather  large  devices  only  pre- 
vents extubation — it  does  not  assure  the  maintenance  of 
the  correct  relationship  between  the  endobronchial  tube  or 
bronchial  blocker  with  its  cuff  and  either  the  upper  lobe 
bronchi  or  the  carina.  This  is  because  the  tube  is  only 
stabilized  at  the  mouth.  The  distal  end  is  free  to  move  in 
or  out  as  the  airways  are  moved  by  shifts  in  the  medias- 
tinum or  hilum  of  the  lung.  Surgical  manipulation  is  an 
obvious  potential  cause  of  malpositioning,  but  changes 
from  supine  to  lateral  decubitus  are  just  as  common  causes, 
whether  for  the  purpose  of  surgery  or  for  performing  re- 
spiratory physiotherapy.  Movement  of  the  DLET  or  bron- 
chial blocker  by  only  millimeters  can  drastically  change 
the  ability  to  ventilate  the  patient. 

When  switching  from  two-lung  ventilation  to  one-lung 
ventilation  using  a  DLET  or  a  bronchial  blocker,  several 
important  aspects  should  be  remembered.  First,  the  long 
narrow  lumens  of  the  DLET  impose  a  large  resistance  to 
air  flow,  so  a  considerable  drop  in  airway  pressure  occurs 
across  the  DLET  during  both  inspiration  and  expiration, 
whether  the  patient  is  breathing  spontaneously  or  mechan- 
ically ventilated.  Since  most  measurements  of  airway  pres- 
sure are  made  proximal  to  the  ET,  a  very  large  peak  pres- 
sure will  be  achieved  during  the  delivery  of  an  otherwise 
reasonable  tidal  volume  (V^).  The  plateau  or  static  airway 
pressure  measured  during  the  inspiratory  pause  should  more 
accurately  reflect  the  distal  airway  pressures.  Second,  the 
Vj  of  a  mechanically-delivered  breath  should  be  adjusted 
downward  to  avoid  hyperinflation  of  the  alveoli  when  pro- 
viding one-lung  ventilation.  During  surgery  a  Vj  of  8-10 
mL/kg  ideal  body  weight  is  recommended,  rather  than  the 
usual  10-15  mL/kg.  Minute  ventilation  can  be  maintained 
by  increasing  the  rate  slightly.  However,  higher  rates  tend 
to  cause  auto-positive  end-expiratory  pressure  because  of 
the  flow  limitation  imposed  by  the  DLET,  so  it  is  neces- 
sary to  limit  the  respiratory  rate  and  adjust  the  inspiratory- 


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671 


Special  Purpose  Endotracheal  Tubes 


expiratory  ratio  setting  of  the  mechanical  ventilator  ac- 
cordingly.'^ 

One  of  the  most  feared  and  lethal  pulmonary  problems 
is  massive  hemoptysis.  Very  few  medical  conditions  re- 
quire as  prompt  a  response  and  intervention  to  maximize 
the  chance  of  a  good  outcome.  Pooling  of  blood  in  the 
airways  and  the  resulting  asphyxiation  (as  opposed  to  ab- 
solute blood  loss),  is  the  immediate  threat  to  life,  so  rapid 
isolation  and  containment  of  the  bleeding  lung  offers  the 
only  hope  of  survival."*  Fortunately,  most  cases  of  mas- 
sive hemoptysis,  defined  as  greater  than  100  mL/24  hours, 
require  less  haste  to  address.'^-"  There  are  a  wide  variety 
of  causes  of  massive  hemoptysis,  but  most  frequently  it  is 
due  to  infection.  Therefore  the  caregiver  must  use  caution 
and  appropriate  measures  to  protect  against  contamination 
of  the  environment  as  well  as  of  the  unaffected  lung. 

In  general,  massive  hemoptysis  is  approached  with  an 
initial  examination  of  the  bronchial  tree.  A  chest  roent- 
genogram can  provide  useful  information  if  a  sufficient 
amount  of  blood  has  accumulated  to  be  visible  and  if  it  is 
restricted  to  a  particular  lobe.  At  the  very  least,  the  chest 
roentgenogram  may  identify  the  side  of  the  lung  that  is 
bleeding.  Flexible  bronchoscopy  can  be  performed  rap- 
idly, with  minimal  patient  preparation,  to  identify  the  source 
of  bleeding,  which  is  essential  to  guide  further  manage- 
ment and,  possibly,  surgery.  If  bleeding  is  brisk,  it  will 
virtually  be  impossible  to  visualize  the  bronchial  tree  with 
a  FOB.  Bronchoscopic  suction  is  limited  and  cannot  re- 
move large  clots.  In  most  circumstances  this  requires  mas- 
sive pulmonary  toilet  and  examination  with  a  rigid  bron- 
choscope under  general  anesthesia.  Clearly  this  is  not  an 
ideal  situation,  but  it  is  potentially  life-saving.  If  bronchos- 
copy fails  to  determine  the  location,  and  the  patient's  con- 
dition allows,  selective  pulmonary  and  bronchial  arteriog- 
raphy can  be  performed. 

In  all  cases  of  brisk  hemoptysis,  the  bleeding  lung  or 
lobe  should  be  isolated  from  the  uninvolved  lung.  This  is 
usually  achieved  by  intubation  with  a  DLET,  especially  in 
circumstances  of  brisk  bleeding.  With  both  cuffs  inflated, 
the  lungs  are  isolated  and  each  side  can  be  intermittently 
lavaged  to  remove  blood  and  to  protect  from  further  con- 
tamination. If  circumstances  allow,  a  small  Fogarty  cath- 
eter can  be  inserted  into  the  bleeding  secondary  bronchus 
to  occlude  the  appropriate  portion  of  the  lung.  From  a 
technical  standpoint,  this  is  much  more  difficult  and  time 
consuming,  and  nearly  impossible  if  the  upper  lobe  is 
involved. 

In  a  dire  emergency,  if  death  is  imminent,  we  recom- 
mend one  of  the  following  approaches.  If  a  left-sided  dou- 
ble-lumen endobronchial  tube  is  available,  intubate  and 
insert  it  until  the  tube  is  wedged  into  the  bronchus.  With 
both  cuffs  inflated,  the  lungs  will  be  isolated  and  can  be 
ventilated  independently  while  lavage  and  suction  can  be 
used  to  determine  which  side  is  bleeding.  Then,  positive 


end-expiratory  pressure  can  be  applied  to  the  bleeding  side 
to  assist  in  slowing  the  bleeding  and  directing  blood  flow 
to  the  uninvolved  lung.  Once  bleeding  has  slowed  suffi- 
ciently, flexible  bronchoscopy  can  commence.  The  other 
approach  is  to  attempt  a  blind  intubation  of  the  right  main 
bronchus  with  a  standard  ET.  This  will  work  temporarily, 
but  is  only  effective  if  the  left  lung  is  the  source  of  bleed- 
ing. Intubation  of  a  main  bronchus  is  the  only  choice  in 
pediatric  cases  of  massive  hemoptysis,  since  DLETs  for 
children  are  not  available.  Intubation  of  either  the  right  or 
left  main  bronchus  with  a  single-lumen  ET  can  be  achieved 
by  maintaining  the  styletted  ET  in  the  "hockey  stick"  con- 
figuration and  rotating  the  tube  in  the  manner  described 
for  insertion  of  the  DLET  into  the  same  bronchus.  Al- 
though this  is  still  a  blind  approach,  the  pediatric  bronchi 
diverge  at  fairly  equal  angles  from  the  trachea  (in  contrast 
to  the  adult  lung,  where  the  right  mainstem  branches  at  a 
less  acute  angle  from  the  carina  than  the  left).  Once  the 
airway  has  been  secured,  ventilation  with  100%  oxygen 
and  positive  end-expiratory  pressure  should  be  initiated, 
and  frequent  lavage  and  suctioning  to  remove  blood  clots 
from  the  lung  should  be  attempted. 

Endotracheal  Tubes  Designed  for  Laser  Surgery 

With  the  advent  of  laser  surgery  of  the  upper  airway,  the 
risk  of  ET  fires  has  lead  to  development  of  specialized, 
ignition-resistant  endotracheal  devices.  There  are  a  variety 
of  different  lasers  in  use,  and  laser-resistant  ETs  may  func- 
tion differently  with  different  laser  systems.-'--  The  risks 
with  tubes  and  laser  therapy  are:  (1)  direct  ignition  of  the 
tube  itself;  (2)  reflection  of  the  laser  from  the  tube  surface, 
causing  accidental  tissue  damage;  and  (3)  cuff  failure  from 
laser  perforation.  ETs  designed  to  be  suitable  for  laser 
surgery  are  stiffer.  bulkier,  less  stable  when  inserted,  and 
more  likely  to  cause  direct  airway  tissue  damage. 

The  Norton  tube  (Fig.  15),  is  a  reusable,  stainless  steel, 
flexible  tube  which  is  unaffected  by  any  laser.  It  has  no 
cuff,  and  a  tracheal  seal  must  be  established  by  packing 
around  the  tube  with  damp  surgical  sponges  or  by  attach- 
ing a  latex  cuff.  Note  that  this  latex  cuff  is  not  laser- 
resistant;  it  can  be  ignited,  and  it  can  be  dislodged  from  the 
tube  and  enter  the  distal  airway.  With  this  tube  it  is  pos- 
sible to  ventilate  without  using  sponge  packing  or  a  cuff, 
but  doing  so  requires  accepting  a  large  ventilation  leak  and 
compensating  for  the  leak  by  increasing  gas  tlows.  Also,  a 
low  fraction  of  inspired  oxygen  must  be  used,  so  as  to 
prevent  increasing  the  fire  hazard  during  tissue  vaporiza- 
tion. This  type  of  tube  is  bulky,  stiff,  and  can  easily  dam- 
age airway  structures  if  not  placed  and  secured  carefully. 
It  is  usually  necessary  to  use  a  stylette  to  maintain  shape 
for  intubating.  The  shiny  surface  reflects  laser  bursts,  which 
can  cause  accidental  burns  to  surrounding  tissues. 


672 


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Special  Purpose  Endotracheal  Tubes 


Fig.  15.  The  stainless  steel  Norton  endotracheal  tube  protects 
against  several  hazards  of  laser  surgery. 


Reflective  foil  wrappings  can  be  applied  to  any  conven- 
tional tube  to  increase  laser  resistance.  Problems  with  this 
approach  include  laser  reflection  damage,  exposed  areas 
that  can  ignite,  an  unprotected  cuff,  and  airway  damage 
from  the  sharp  edges  of  the  wrappings.-'  Foils  may  un- 
wrap during  use,  thus  interfering  with  the  surgery  and 
making  tube  removal  difficult.-"* 

Tubes  of  various  laser-resistant  materials  have  been  de- 
veloped. None  are  completely  safe  from  damage  from  di- 
rect laser  hits,  but  they  do  not  burst  into  flame. ^'^  The 
Laser-Shield  II  (Xomed-Trease  Inc.  Jacksonville.  Florida) 
(Fig.  16),  is  a  silicone  tube  with  an  inner  aluminum  wrap 
and  an  outer  Teflon  coating.  It  has  been  used  with  pota- 
sium-titanyl-phosphate  (KTP)  lasers,  neodynium-yttrium- 
aluminum-garnet  (Nd-YAG)  lasers,  and  COt  lasers.  The 
cuff  is  not  laser  resistant,  and  contains  a  blue  marker  to 
identify  perforation.  To  prevent  fire,  the  cuff  should  be 
inflated  with  water  or  saline  solution.  The  tube  distal  to  the 
cuff  is  also  unprotected.  The  Laser  Flex  tube  (Mallinck- 
rodt  Inc,  Pleasanton.  California)  (Fig.  17)  is  a  stainless 
steel  tube  with  a  matte  finish.  It  can  be  used  uncuffed  or 
with  two  cuffs  attached  in  series  (as  with  other  laser  tube 
cuffs,  these  should  be  inflated  with  water  or  saline  solu- 
tion). The  Laser  Flex  tube  is  designed  for  use  with  the  CO, 
laser  and  the  KTP  laser,  but  not  with  the  Nd-YAG  laser. 
The  Sheridan  red  rubber,  copper-wrapped  La.ser  Trach  tube 
(Kendall  Healthcare,  Mansfield,  Massachusetts)  (Fig.  18) 


Fig.  16.  The  Laser  Shield  II  endotracheal  tube  is  metal-wrapped 
and  covered  with  laser-resistant  material.  (Photograph  courtesy  of 
Xomed-Trease  Inc.) 


is  also  for  use  with  the  CO,  laser  and  KTP  la.ser.  It  comes 
with  pledgets  that  are  to  be  soaked  and  packed  around  the 
cuff  to  protect  the  cuff.  The  Lasertubus  (Riisch  Inc,  Du- 
luth,  Georgia)  (Fig.  19)  is  made  of  white  rubber  and  has  a 
cuff-within-a-cuff  design.  Its  surface  is  covered  with  a 
sponge  material  that  can  be  soaked  in  water  to  reduce 
ignition  potential.  Refection  is  not  a  problem  with  this 
tube,  which  can  be  used  with  the  argon  laser,  the  Nd-YAG 
laser,  and  the  CO,  laser.  The  Bivona  Fome-Cuf  laser  tube 
(Bivona  Medical  Technologies,  Gary,  Indiana)  was  de- 
signed to  solve  the  perforated-cuff-deflation-problem.  It 
consists  of  an  aluminum  wrapped  silicone  tube  with  a 
Bivona  foam-filled  self-inflating  cuff.  Even  when  pene- 
trated by  the  laser,  the  cuff  maintains  a  seal.  The  tube, 
however,  is  poorly  resistant  to  all  lasers,  and  fires  can 
occur.  If  the  cuff  is  penetrated,  it  can  no  longer  be  deflated 
for  removal.  From  the  variety  of  different  designs  avail- 
able, it  is  apparent  that  no  one  design  is  ideal  for  all  lasers 
and  all  procedures.  Continuing  innovation  is  likely  in  this 
area  of  tube  manufacturing. 

Endotracheal  Tubes  with  Additional  Ports 

Several  issues  have  arisen  to  advance  the  development 
of  tubes  with  additional  ports.  One  of  these  is  the  recog- 
nition that  many  drugs  can  be  quickly  administered  by 
way  of  the  lungs  in  situations  where  intravenous  access 
has  not  yet  been  established.  During  medical  einergencies. 


Respiratory  Care  •  June  1999  Vol  44  No  6 


673 


Special  Purpose  Endotracheal  Tubes 


Fig.  17.  The  Laser  Flex  endotracheal  tube  comes  with  a  double- 
cuff  or  no  cuff.  (Photograph  courtesy  of  Mallinckrodt  Inc.) 


intravenous  access  may  not  be  quickly  obtainable,  and  an 
ET  is  often  in  place  before  intravenous  access  is  estab- 
lished, so  drug  administration  via  the  lung  is  an  important 
option  in  certain  emergency  situations.  Special  ETs  with 
medication  ports  embedded  in  the  tube  wall  are  now  avail- 
able, and  these  tubes  allow  drugs  to  be  given  without 
interrupting  mechanical  ventilation.  The  medication  port 
may  include  a  one-way  valve  or,  if  not,  must  be  capped  to 
prevent  loss  of  gas  during  positive  pressure  ventilation. 

The  American  Heart  Association  has  moved  intubation 
up  on  the  priority  list  in  treating  cardiac  arrest.  During 
treatment  of  ventricular  fibrillation,  after  defibrillation 
(which  should  be  attempted  up  to  3  times  without  inter- 
ruption even  for  airway  management),  the  next  priority  is 
intubation  to  allow  drug  administration  (epinephrine)  and 
ventilation  to  treat  acidosis.  Current  recommendations  sug- 
gest that  2-2.5  times  the  intravenous  dose  should  be  ad- 
ministered through  the  ET,  in  at  least  10  mL  volume. 
However,  experimental  data  suggest  that  this  dose  should 
probably  be  increased  to  5-10  times  the  usual  dose,  at  least 
for  epinephrine.-''  Emergency  drugs  that  can  be  adminis- 
tered to  the  lung  through  the  ET  include:  epinephrine, 
norepinephrine,  lidocaine,  atropine,  diazepam,  and  nalox- 


Fig.  18.  The  Laser  Trach  endotracheal  tube  has  a  copper  foil  wrap- 
ping and  a  fabric  covering. 


one.  Figure  20  shows  an  ET  that  features  a  medication 
lumen. 

Tracheal  gas  insufflation  can  be  performed  through  a 
distal  tracheal  lumen.  Decreased  anatomical  dead  space 
and  increased  arterial  oxygenation  can  result  when  several 
liters  of  oxygen  are  insufflated  through  an  additional  lu- 
men. The  effectiveness  of  this  technique  in  acute  respira- 
tory distress  syndrome  and  asthma  may  be  related  to  the 
proximity  of  gas  flow  to  the  carina.-''-*'  Separate  catheters 
advanced  deeper  into  the  airway  may  be  more  effective, 
but  special  ETs  with  an  additional  port  may  allow  similar 
benefit  with  less  risk.-''  The  contribution  of  this  collateral 
gas  to  increased  peak  airway  pressure  (and  Vp)  should  be 
taken  into  account  when  considering  using  this  technique 
of  ventilatory  support."'  '''' 

Distal  airway  pressures  can  be  measured  through  an 
additional  lumen.  Figure  21  shows  tubes  designed  for  op- 
timization of  mechanical  ventilation  and  reduction  of  the 
work  of  breathing  by  measuring  airway  pressures  at  the 
tracheal  end  of  the  airway.  Triggering  of  demand  systems 
and  improvement  of  patient-ventilator  synchrony  can  be 
enhanced  by  distal  airway  pressure  measurements.  The 


674 


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Special  Purpose  Endotracheal  Tubes 


Fig.  19.  The  Lasertubus  endotracheal  tube  is  constructed  of  white 
latex  rubber.  (Photography  courtesy  of  RiJsch  Inc.) 


early  detection  of  a  partially  obstructed  airway  can  be 
facilitated  by  recognition  of  a  difference  in  proximal  and 
distal  pressures.  Because  of  these  benefits,  distal  and  prox- 
imal airway  pressure  monitoring  should  be  considered  in 
all  patients  receiving  mechanical  ventilation,  but  especially 
in  those  who  are  very  tenuous  or  difficult  to  wean. 

The  Hi-Lo  Jet  (Mallinckrodt  Inc,  Plea.santon,  Califomia) 
tube  (Fig.  22)  was  designed  to  provide  high-frequency  jet 
ventilation  through  an  additional  port  embedded  in  the 
wall  of  the  ET.  The  tube  is  more  rigid  than  conventional 
tubes,  so  as  to  preserve  a  straight  path  for  the  jet  gas  flow. 
The  bias  flow  and  positive  end-expiratory  pressure  can  be 
added  with  a  circuit  attached  to  the  ET  connector.  When 
using  high  frequencies,  adequate  gas  entrainment  from  the 
bias  tlow  circuit  is  necessary  to  produce  adequate  venti- 
lation. The  bias  circuit  is  also  the  conduit  for  exhalation, 
and  adequate  exhalation  time  during  the  jet  cycle  is  re- 
quired. 

Intubated  and  ventilated  patients  are  at  high  risk  for 
developing  pulmonary  infections.  The  incidence  of  noso- 


Fig.  20.  The  medication  lumen  embedded  in  the  endotracheal  tube 
wall  allows  tracheal  drug  administration  without  interrupting  ven- 
tilation. (Photograph  courtesy  of  Mallinckrodt  Inc.) 


comial  ventilator-associated  pneumonia  is  reported  to  be 
between  10%  and  60%,  and  is  associated  with  increased 
mortality.^-*-'''  Lung  infection  can  result  from  aspiration  of 
bacteria-laden  oropharyngeal  secretions  around  the  ETcuff. 
The  route  of  oral  colonization  is  believed  to  be  from  the 
stomach.  Preventive  strategies  include  reducing  gastric  col- 
onization by  maintaining  an  acid  environment,  and  selec- 
tive decontamination  with  nonabsorbable  antibiotics."' " 
Reducing  the  aspirated  bacterial  load  can  also  be  accom- 
plished by  oral  and  subglottic  secretion  removal."*  A  re- 
cent modification  of  the  ET  shown  in  Figure  2.^  allows 
continuous  aspiration  of  subglottic  secretions.  Preliminary 
results  with  this  tube  suggest  a  decrease  in  the  frequency 
and  a  delay  in  the  onset  of  ventilator-associated  pneumo- 
nia.'" 

Topical  anesthesia  of  the  airway  may  improve  patient 
tolerance  of  intubation.  In  fragile  patients,  spraying  the 


Respiratory  Care  •  June  1999  Vol  44  No  6 


675 


Special  Purpose  Endotracheal  Tubes 


Fig.  21.  Endotracheal  tubes  with  extra  lumens  for  distal  airway 
pressure  measurement.  (Photograph  courtesy  of  Mallinckrodt  Inc.) 


Fig.  23  A:  Endotracheal  tube  designed  to  allow  aspiration  of  sub- 
glottic secretions,  which  assists  in  prevention  of  nosocomial  in- 
fections. B:  Close-up  of  evacuation  port. 


Fig.  22.  The  additional  port  on  this  endotracheal  tube  allows  jet 
ventilation.  (Photograph  courtesy  of  Mallinckrodt  Inc.) 


vocal  cords  and  larynx  with  a  local  anesthetic  prior  to 
intubation  decreases  the  expected  rise  in  blood  pressure 
and  reduces  the  incidence  of  cardiac  stress.  This  rise  in 
blood  pressure  during  ET  placement  is  also  a  concern  in 
patients  with  altered  intracranial  compliance  (head  injury, 
hemorrhage,  or  tumors)  and  measures  (including  deep  an- 
esthesia and  topical  anesthesia)  are  often  needed  to  pre- 
vent brain  herniation  during  intubation.  Tracheal  suction 
and  movement  of  the  tube  during  nursing  maneuvers  may 


also  stimulate  a  hypertensive  response  with  an  increase  in 
intracranial  pressure.  Local  anesthetic  administered  down 
the  ET  can  modify  this  response,  but  the  larynx  remains 
unanesthetized  when  medications  are  administered  through 
the  ET.  A  special  ET  designed  with  an  additional  injection 
port  with  multiple  side  holes  on  the  outside  of  the  tube 
(Fig.  24)  allows  local  anesthetic  administration  to  the  lar- 
ynx and  upper  airway.  Uses  of  this  special  purpose  tube 
include:  head  and  neck  surgery  (to  prevent  coughing  dur- 
ing head  manipulation),  in  patients  with  cardiovascular 


676 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Special  Purpose  Endotracheal  Tubes 


Fig.  24.  This  special  purpose  endotracheal  tube  has  a  port  for 
injecting  local  anesthetic  to  the  trachea  and  larynx.  (Photograph 
courtesy  of  Mallinckrodt  Inc.) 


instability,  head  injury  patients,  and  in  patients  in  whom 
the  tube  is  anticipated  to  be  replaced  electively. 

The  Pittsburgh  Talking  Tracheostomy  tube  (Fig.  25)  is 
designed  to  allow  phonation  by  tracheostomized  patients. 
This  tube  has  an  extra  lumen  through  which  continuous  or 
intermittent  gas  flow  can  pass  upward  through  the  larynx, 
thus  allowing  speech  in  patients  who  would  otherwise  find 
it  difficult  or  impossible. 

Special  Tubes  and  Devices  to  Aid  with  Intubation 

Several  ET  modifications  to  facilitate  intubation  are 
available.  The  ANSI  standards  require  that  ETs  have  a 
preformed  curve  to  help  with  tracheal  placement.  During 
direct  visualization,  the  larynx  is  usually  seen  to  lie  above 
the  oral  floor  plane.  The  tube  tip  must  be  directed  anteri- 
orly to  enter  the  trachea.  Anterior  directioning  of  the  tip  is 
especially  important  during  nasal  intubation.  The  ANSI 
material  standards  require  the  tube  to  soften  at  body  tem- 


Fig.  25.  Pittsburgh  Talking  Tracheostomy  tube.  Gas  flow  through 
the  larynx  allows  phonation  for  patients  with  tracheostomies. 


Fig.  26.  A  malleable  stylette  allows  shaping  the  endotracheal  tube 
to  the  desired  curve.  The  tube  is  stiffened,  which  can  facilitate 
intubation. 


perature  to  conform  to  this  crooked  anatomical  course,  so 
as  to  prevent  undue  pressure  on  the  upper  airway  struc- 
tures and  trachea.  During  repeated  intubation  attempts,  the 
tube  may  soften  and  not  maintain  the  preformed  curve, 
which  further  complicates  intubation.  The  ET  can  be  tem- 
porarily stiffened  with  a  malleable  stylette  to  allow  ante- 
rior directioning  of  the  tip.  A  typical  intubation  shape,  like 
a  hockey  stick,  is  shown  in  Figure  26.  Depending  on  the 
patient's  actual  anatomy,  the  stylette  can  be  formed  to  help 
bypass  an  obstruction.  Pediatric  ETs  are  very  floppy  and  a 
stylette  is  frequently  useful  in  achieving  tracheal  intuba- 
tion. 

The  Endotrol  tube  (Mallinckrodt  Inc,  Pleasanton,  Cali- 
fornia) (Fig.  27)  has  an  embedded  string  that,  when  pulled. 


Respiratory  Care  •  June  1999  Vol  44  No  6 


677 


Special  Purpose  Endotracheal  Tubes 


Fig.  27.  The  Endotrol  endotracheal  tube  features  an  embedded 
string  that  flexes  the  tube  anteriorly,  facilitating  intubation. 

increa.scs  (or  restores)  the  tube's  curvature,  thus  facilitat- 
ing intubation.  When  used  with  a  stylette,  the  tip  alone  can 
be  controlled  and  directed  towards  the  larynx.  This  tube  is 
especially  useful  during  blind  nasal  intubation.^" 

A  modification  of  the  stylette  technique  is  the  Flexguide. 
which  is  a  combined  malleable  stylette  and  FOB.  This 
device  permits  a  fixed  curve  in  the  tube  as  well  as  visu- 
alization of  the  area  in  front  of  the  ET.  confirming  correct 
tracheal  placement. 

Another  modification  of  the  malleable  stylette  is  the 
lighted  slylettc  (Fig.  28).  which  is  equipped  with  a  bright 
light  on  the  tip  to  facilitate  blind  intubation."  The  lighted 
stylette  is  useful  for  both  oral  and  nasal  intubation,  and  in 
both  adults  and  children. ^-^'  The  tube  and  the  lighted 
slylettc  (shaped  like  a  hockey  stick)  are  inserted  blindly 
into  the  moulh  or  nose  after  topical  analgesia  or  under 
general  anesthesia.  The  room  is  darkened  and  transillumi- 
nation of  the  airway  allows  differentiation  of  the  esopha- 
gus from  the  trachea.  A  bright,  narrow  light  in  the  midline 


below  the  thyroid  cartilage  indicates  that  the  trachea  has 
been  entered,  while  a  diffuse  glow  laterally  indicates  that 
the  tube  is  in  the  esophagus.  With  this  implement,  suc- 
cessful tracheal  intubation  depends  on  normal  neck  anat- 
omy, good  analgesiii/anesthesia,  and  no  interfering  lesions. 
Since  this  is  a  blind  technique,  successful  tracheal  intuba- 
tion should  be  confirmed  with  routine  measures  such  as 
auscultation  and  measurement  of  exhaled  CO^.  This  is  not 
an  emergency  airway  technique,  since  the  procedure  can 
take  a  significant  amount  of  time  and  must  be  performed 
in  the  dark  (in  which  situation,  ob.servation  of  the  patient's 
clinical  status  is  suboptimal).  This  technique  may  be  con- 
sidered in  patients  during  difficult  intubation  but  with  an 
easy  airway  or  adequate  spontaneous  ventilation.  The  pa- 
tient with  a  suspected  cervical  spine  injury,  in  cervical 
traction,  and  who  is  breathing  spontaneously  is  an  excel- 
lent candidate  for  use  of  this  technique.-*-* 

The  laryngeal  mask  airway  can  provide  a  route  for  in- 
tubation, since  it  usually  rests  directly  in  front  of  the  la- 
ryngeal opening.  A  small  (6.5-7.0  mm),  cuffed  tube  can 
be  inserted  through  the  LMA  and  into  the  trachea,  achiev- 
ing a  secure,  protected  airway  during  an  emergency. -'■'^  How- 
ever, the  combination  must  be  left  in  place,  since  removal 
of  the  LMA  over  the  ET  is  difficult  and  can  result  in 
extubation.  An  intubating  stylette  (Eshelmann  Stylette  or 
gum  bougie),  with  its  additional  length,  can  be  inserted 
though  the  tube,  allowing  reinsertion  of  a  larger  tube  fol- 
lowing removal  of  the  LMA.-*^  A  newly-designed  rigid 
metal  LMA,  the  LMA-FasTrach  (The  Laryngeal  Mask  Co 
Ltd,  United  Kingdom)  (Fig.  29)  has  a  larger  internal  di- 
ameter and  stabilizing  flange  that  allows  a  special  long, 
flexible,  silicone  ET  to  be  blindly  placed  into  the  trachea, 
with  a  high  success  rate.  The  intubating  LMA  can  then  be 
withdrawn  over  the  tube,  using  the  supplied  pusher  or 
stabilizer  and  leaving  the  trachea  safely  intubated. 

Head  and  Neck  Surgery 

Dental  procedures  and  surgery  of  the  head  and  neck 
pose  special  problems  for  airway  management  and  endo- 
tracheal intubation.  While  special  equipment  is  helpful  in 
securing  the  airway  initially,  close  collaboration  between 
the  anesthesiologist  and  operating  surgeon  is  necessary  to 
prevent  inadvertent  airway  loss  and  patient  harm  during 
the  surgical  procedure.  The  major  airway  problems  during 
these  procedures  are  movement  of  the  ET  and  kinking  of 
the  tube,  causing  inadequate  gas  exchange.  While  these 
problems  can  occur  during  any  surgical  procedure,  they 
are  more  likely  during  head  and  neck  procedures,  since  the 
tube;  is  often  part  of  the  sterile  field  and  is  often  moved  by 
the  surgeon.  Also,  both  visual  and  manual  access  to  the  ET 
is  limited,  and  when  problems  arise  they  are  not  easily 
diagnosed  or  solved  without  contamination  of  the  incision. 


678 


Respiratory  Care  •  June  1999  Vol  44  No  6 


SPEriAl,  PURPOSF.  EnDOTRACHFAI,  Tl'BRS 


Fig.  28.  Three  types  of  malleable  stylette,  each  with  a  bright  light  at  the  tip.  Because  the  light  illuminates  the  necl<  differently  from  the  trachea 
and  esophagus,  it  facilitates  blind  tracheal  intubation. 


Low  profile  tubes  with  preformed  bends  have  been  de- 
signed to  reduce  some  of  these  risks.  The  bends  can  be 
straightened  with  a  stylette  to  facilitate  initial  tracheal  place- 
ment. One  such  ET  is  the  RAE  (Ring,  Adair,  Elwin  tube, 
Mallinckrodt  Inc,  Pleasanton.  California)  (Fig.  30).  which 
come  in  a  variety  of  sizes,  cuffed  and  uncuffed  models. 
and  shaped  for  oral  or  nasal  intubation.  The  preformed 
bend  rests  at  the  chin  or  external  nares,  and  prevents  oc- 
clusion under  the  surgical  drapes  or  on  the  field  during  the 
surgical  procedure.  The  location  of  the  bend  is  based  on 
the  diameter  of  the  tube.  The  tube  tip  may  be  too  long 
(resulting  in  bronchial  intubation)  or  too  short  (resulting  in 
extubation)  depending  on  the  particular  patient's  anato- 
my.-*^ Passage  of  a  suction  catheter  through  the  bend  is 
usually  difficult  and  may  be  impossible.  Head  extension  or 
flexion  after  securing  the  airway  can  move  the  tip  of  the 
tube  too  far  into,  or  out  of,  the  larynx.  For  patients  who  do 
not  fit  well  to  the  pre-formed  tubes,  the  RAE-Flex 
(Mallinckrodt  Inc,  Pleasanton,  California)  tube  has  a  wire- 
reinforced  flexible  section  that  can  be  bent  to  suit  the 
patient's  anatomy.  The  RAE-Flex  tube  can  be  used  for  oral 


Fig.  29.  The  LMA-FasTrach  intubating  laryngeal  mask  airway  (LMA) 
consists  of  a  metal  LMA,  silastic  tube,  and  stabilizers  or  pushers  to 
allow  the  LMA  to  be  removed,  while  leaving  the  endotracheal  tube 
in  the  trachea. 


Respiratory  Care  •  June  1 999  Vol  44  No  6 


679 


Special  Purpose  Endotracheal  Tubes 


Fig.  30.  Preformed  RAE  endotracheal  tubes  provide  low-profile  airways  for  head  and  neck  procedures. 


or  nasal  intubation.  Passage  of  a  suction  catheter  may  be 
less  difficult  through  a  RAE-Flex  tube  than  through  the 
conventional  RAE  tube. 

Tubes  that  are  flexible  and  resist  kinking  are  important 
additions  to  head  and  neck  surgical  procedures.  Figure  31 
shows  how  some  tubes  are  spiral-embedded  with  wire  or 
nylon  fibers  and  are  made  of  rubber,  PVC,  or  silicone. 
They  arc  flexible  and  maintain  their  internal  diameter  when 
bent.  They  also  resist  external  compression.-"*  However,  if 
bitten  or  otherwise  crushed,  the  tube  may  be  permanently 
narrowed."*'*  These  tubes  are  often  passed  through  the  stoma 
of  an  existing  tracheotomy,  and  can  be  placed  aseptically 
by  the  surgeon  during  the  procedure.  If  the  tube  is  made  of 
silicone,  it  will  be  very  limp,  making  intubation  difficult. 
Nasal  intubation  may  be  impossible  because  of  narrow 
nasal  passages.  Accidental  removal  frequently  occurs,  and 
suturing  the  tube  in  place  is  recommended.  Due  to  the  high 
frequency  of  inadvertent  extubation,  these  ETs  are  usually 
removed  and  replaced  with  conventional  ETs  at  the  end  of 
the  surgical  procedure  if  continued  airway  cannulation  is 
required.''"  These  tubes  cannot  be  shortened  without  dam- 
aging the  spiral  fibers  and  tube  integrity.  While  this  tube 
design  solves  one  problem,  a  high  degree  of  vigilance  is 
necessary  to  prevent  other  problems. 

Normal  speech  following  laryngectomy  is  impossible. 
Over  the  past  20  years,  creation  of  a  controlled  tracheo- 
esophageal fistula  (TEF)  to  allow  esophageal  speech  has 
been  perfected.  With  a  TEF,  air  from  the  lungs  can  be 
exhaled  through  the  fistula  into  the  esophagus  and  phar- 


/ 

■ 

k^^^^^^^^^^^^' 

'■'r  .^^^^^^^^^^^^^^^^^^^^^H^                    '^^M 

^^^^1 

Fig.  31 .  This  spiral  wrapped  endotracheal  tube  resists  kinking. 


680 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Special  Purpose  Endotracheal  Tubes 


Fig.  32.  The  Bloom-Singer  tracheal  esophageal  fistula  (TEF)  tube 
allows  esophageal  speech  following  laryngectomy. 


I 


Fig.  33.  The  Provox  II  tracheoesophageal  fistula  (TEF)  prosthesis. 


Fig.  34.  Five  types  of  tracheoesophageal  fistula  (TEF)  prostheses 
developed  around  the  Provox  shape.  (Modified  from  Reference 
51,  with  permission.) 


ynx,  producing  a  vibration  that  can  be  articulated  into 
verbal  speech.  A  silicone  prosthesis  is  used  to  prevent 
closure  of  the  fistula,  and  its  one-way  valve  reduces  the 
likelihood  of  aspiration  of  gastric  contents.  To  speak,  the 
patient  must  manually  obstruct  his  tracheal  stoma,  usually 
with  a  single  digit,  and  exhale  through  the  TEF.  Several 
different  prostheses  have  been  developed.  The  earliest  pros- 
thesis was  described  by  Bloom  and  Singer;  this  device 
(Fig.  32)  is  in  wide  use  throughout  the  world.  Another 
device  is  the  Provox  tube  (Fig.  33).  A  series  of  these 
devices  (Fig.  34)  were  developed  in  the  Netherlands,  and 
include  the  Groningen,  Nijdam,  and  Provox  variants.  These 
can  be  interchanged  using  the  unique  features  of  each  to 
solve  individual  patient  problems.^'  When  these  patients 
are  seen  clinically,  the  presence  and  function  of  the  pros- 
thesis should  be  confirmed.  If  intubation  is  required  for  a 
surgical  procedure,  the  prosthesis  can  be  removed  or  left  in 
place.  If  left  in  place,  it  is  necessary  to  confirm  at  the  end 
of  the  procedure  that  it  is  still  in  place.  If  prolonged  intu- 
bation is  needed,  the  prosthesis  can  be  removed  to  avoid 
pulmonary  aspiration  of  gastric  material  or  the  device  it- 
self. 

Summary 

This  article  has  described  only  selected  special  purpose 
ETs  in  common  use  today.  There  are  additional  devices 
not  mentioned,  which  have  small  followings  or  very  lim- 
ited applications.  Undoubtedly,  further  innovations  will  be 
available  in  the  near  future,  but  clinicians  and  researchers 
should  bear  in  mind  that  very  few  standards  protect  users 
from  poor  ET  designs.  Thus,  new  devices  should  be  care- 
fully assessed  prior  to  clinical  application. 


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demand  valve  triggering  and  total  work  during  continuous  positive 
airway  pressure  ventilation.  Chest  1996:1 10(3):775-783. 

34.  Wenzel  RP.  Hospital-acquired  pneumonia:  overview  of  the  current 
state  of  the  art  for  prevention  and  control.  Eur  J  Clin  Microbiol  Infect 
Dis  1989;8(l):56-60. 

35.  Jimenez  P,  Torres  A,  Rodriguez-Roisin  R,  de  la  Bellacasa  JP,  Aznar 
R,  Galell  JM,  Agusti-Vidal  A.  Incidence  and  etiology  of  pneumonia 
acquired  during  mechanical  ventilation.  Crit  Care  Med  1989;  17(9); 
882-885. 

36.  Driks  MR,  Craven  DE,  Celli  BR.  Manning  M,  Burke  RA,  Garvin 
GM,  et  al.  Nosocomial  pneumonia  in  intubated  patients  given  su- 
cralfate as  compared  to  antacids  or  histamine  type  2  blockers.  The 
role  of  gastric  colonization.  N  Engl  J  Med  1987;3I7(22):1376-I382. 

37.  Stoutenbeek  CP,  van  Saene  HK.  Prevention  of  pneumonia  by  selec- 
tive decontamination  of  the  digestive  tract  (SDD).  Intensive  Care 
Med  1992;l8(Suppl  1):S18-S23. 

38.  American  Thoracic  Society,  Hospital-acquired  pneumonia  in  adults: 
diagnosis,  assessment  of  severity,  initial  antimicrobial  therapy,  and 
preventive  strategies.  A  Consensus  Statement,  November  1995.  Am  J 
Respir  Crit  Care  Med  1996;151(5):171 1-1725. 

39.  Valles  J,  Artigas  A,  Rello  J,  Bonsoms  N,  Fontanals  D,  Blanch  L,  et 
al.  Continuous  aspiration  of  subglottic  secretions  in  preventing  ven- 
tilator-associated pneumonia.  Ann  Intern  Med  1995;122(3):I79-186. 

40.  Asai  T.  Endolrol  tube  for  blind  nasotracheal  intubation  (letter).  An- 
aesthesia I996;5U5):507. 

41.  Ainsworth  QP,  Howells  TH.  Transilluminated  tracheal  intubation. 
Br  J  Anaesth  I989;62(5):494^97. 

42.  Verdile  VP.  Chiang  JL.  Bedger  R,  Stewart  RD,  Kaplan  R,  Paris  PM. 
Nasotracheal  intubation  using  a  flexible  lighted  stylet.  Am  J  Emerg 
Med  I990;19(5):506-510. 

43.  Holzman  RS.  Nargozian  CD,  Florence  FB.  Lightwand  intubation  in 
children  with  abnormal  upper  airways.  Anesthesiology  1988:69(5): 
784-787. 

44.  Weis  FR  Jr.  Light-wand  intubation  for  cervical  spine  injuries  (letter). 
Anesth  Analg  I992;74(4):622. 

45.  Heath  ML.  Endotracheal  intubation  through  the  laryngeal  mask:  help- 
ful when  laryngoscopy  is  difficult  or  dangerous.  Eur  J  Anaesth  1990; 
4(Suppl):4l-45. 

46.  Brimacombe  J,  Berry  A.  Placement  of  a  Cook  airway  exchange 
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48(4):35 1-352. 

47.  Black  AE.  Mackersie  AM.  Accidental  bronchial  intubation  with  RAE 
tubes  (letter).  Anaesthesia  1991;46(1):42^3. 

48.  Beckers  HL.  Use  of  a  stabilized,  armored  tube  in  maxillofacial  .sur- 
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49.  Martens  P.  Persistent  narrowing  of  an  armoured  tube  (letter).  An- 
aesthesia I992;47(8):716-7I7. 

50.  Ripoll  1.  Lindhold  CE,  Carroll,  R,  Grenvik  A.  Spontaneous  disloca- 
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51.  Van  Den  Hoogen  EJ.  Oudes  MJ.  Hombergen  G,  Nijdam  HF,  Manni 
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tive clinical  coiriparison  based  on  845  replacements.  Acta  Otolaryn- 
gol (Stockh)  1 996;  11 6(1):  II 9- 124. 


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Special  Purpose  Endotracheal  Tubes 


Appendix  1 


Subdivisions  of  the  American  Society  for  Testing  and  Materials 
F-29  Technical  Committee 

F29.01  Division  One  on  Anesthesia  Apparatus 
F29.01.01  Anesthesia  Gas  Machine 
F29.01.02  Breathing  Systems/Performance 
F29.01.03  Connectors  &  Adapters 
F29.01.04  Breathing  Systems  and  Antidisconnect  Fittings 
F29.01.05  Pollution  Control 
F29.01 .06  Anesthetic  Agent  Analyzers 
F29.01.07  Lung  Ventilators  for  Use  in  Anesthesia 
F29.01.08  Gas  Mixers 
F29.01.09  Anesthesia  Workstations 

F29.02  Division  Two  on  Endoscopes  and  Airways 
F29.02.01  Tracheal  Tubes 
F29.02.02  Naso/Oropharyngeal  Airways 
F29.02.03  Breathing  Tubes/Bags 
F29.02.05  Tracheostomy  Tubes  Adult 
F29.02.06  Tracheostomy  Tubes  Pediatric 
F29.02.07  Laryngoscopes  Bulbs  /  Handles  /  Blades  (Rigid) 
F29. 02.08  Laryngoscopes  and  Bronchoscopes  (Flexible) 
F29.02.09  Bronchoscopes  (Rigid) 
F29.02.10  Tracheal  Tubes  for  Laser  Surgery 
F29.02.il  Suction  Catheters 

F29.03  Division  Three  on  Ventilators  and  Ancillary  Devices 

F29.03.01  Lung  Ventilators  (Other  than  for  Anesthetic  Use) 

F29.03.03  Resuscitators 

F29.03.04  Harmonization  of  Alarms 

F29.03.06  Cutaneous  Gas  Monitoring 

F29.03. 07  Humidifiers 

F29.03.08  Oxygen  Analyzers 

F29. 03. 09  Home  Care  Ventilators 

F29.03.10  Pulse  Oximeters 

F29.03.il  Capnometers 

F29.04  Division  Four  on  Terminology 

F29.06  Division  Six  on  Medical  Gas  Supply  Systems 
F29.06.02  Oxygen  Concentrators 

F29.07  Division  Seven  on  Suction  and  Drainage 

F29.07.01  Medical/Surgical  Suction  Systems 


Respiratory  Care  •  June  1999  Vol  44  No  6  683 


Special  Purpose  Endotracheal  Tubes 


Discussion 

Bishop:  A  couple  of  years  ago  I  was 
fascinated  by  a  description  of  a  spe- 
cialty endotracheal  tube  that  appeared 
in  Anesthesiology  from  the  NIH  [Na- 
tional Institutes  of  Health]  group  led 
by  Kolobow.'  It  was  a  tube  intended 
for  the  patient  undergoing  prolonged 
ventilation,  and  it  was  really  very  dif- 
ferent from  most  of  the  tubes  we  have 
now.  It  used  relatively  high-tech  ma- 
terial, which  gave  it  a  higher  inner- 
diameter-to-outer-diameter  ratio.  It 
showed  a  lot  of  promise.  It  seemed  to 
prevent  secretions  from  getting  past 
the  cuff,  it  caused  less  tracheal  dam- 
age in  animal  tests,  and  it  seemed  to 
be  able  to  ventilate  with  acceptable 
pressures.  The  last  time  I  talked  to 
him,  he  hadn't  been  able  to  get  a  man- 
ufacturer to  make  it  because  they  felt 
that  it  would  be  too  expensive  for  a 
very  small  market.  I  don't  know  if 
anyone  else  knows  what's  up  with  that, 
or  if  other  people  are  aware  of  the 
design,  but  I  think  it  has  many  of  the 
features  we'd  all  like  to  see  in  a  tube 
that's  used  for  prolonged  ventilation. 

REFERENCE 

L  Kolobow  T,  Tsuno  K,  Rossi  N,  Aprigli- 
ano  M.  Design  and  development  of  ullra- 
thin-walled,  nonkinking  endotraclieal 
tubes  of  a  new  "no-pressure"  laryngeal 
seal  design:  a  preliminary  report.  Ane.s- 
thesiology  1 994;8 1  (4):  1 06 1  - 1 067. 

Durbin:  I'm  not  familiar  with  that 
particular  tube.  There  have  been  sev- 
eral thousand  patents  issued  over  the 
years  for  variations  in  airway  devices, 
99%  of  which  never  came  into  pro- 
duction. I  think  marketing  factors  are 
important.  We've  talked  about  one  of 
these  tubes  here,  the  laryngeal  aspi- 
rating tube.  I  think  the  device  is  going 
to  face  a  similar  future  unless  a  clear- 
cut  indication  (value  and  cost-benefit) 
in  a  large  patient  population  can  be 


*David  J  Pierson  MD.  Division  of  Pulmonary  & 
Critical  Care  Medicine.  Department  of  Medicine, 
University  of  Washington.  Seattle,  Washington. 


identified.  Otherwise,  it  will  fall  by 
the  wayside  as  well. 

Pierson:*  Just  to  amplify  on  that: 
what  you've  touched  on  is  a  really 
important  issue  from  the  manufactur- 
er's perspective.  A  manufacturer  who 
makes  millions  of  tubes  will  not  in- 
vest in  a  new  tube  design  that  costs 
just  as  much  or  more  to  manufacture 
if  the  new  model  is  only  going  to  sell 
a  few  hundred  copies.  I  believe  that's 
one  of  the  problems  that  we've  had 
with  getting  some  of  these  specialty 
tubes  into  clinical  u.se  for  the  inten- 
sive care  unit,  as  opposed  to  using  them 
in  the  operating  room. 

Durbin:  Let's  go  back  to  the  laryn- 
geal mask  airway,  which  everyone 
seems  so  enthusiastic  about  today  in  a 
number  of  situations.  That  tube  was 
designed  by  Archie  Brain  in  England 
ten  years  ago,  is  still  made  by  hand, 
and  sells  for  over  $200  per  de- 
vice.Although  there  are  disposable 
models  now  made  that  are  a  little  less 
expensive,  they're  not  nearly  as  good. 
The  cost  has  limited  the  application  of 
this  device,  which  we  know  beyond  a 
shadow  of  a  doubt  is  an  advance  in 
airway  management. 

Hurford:  Clearly,  cost  is  a  big  fac- 
tor when  we  go  to  make  a  custom 
endotracheal  tube  for  particular  pa- 
tients who  have  unique  tracheal  pa- 
thology or  something  like  that.  We  can 
get  those  tubes  made,  but  at  $100, 
$200,  $300  on  the  run  for  two  tubes  or 
something  like  that,  and  certainly 
that's  difficult.  The  other  difficulty 
from  a  manufacturing  point  of  view 
seems  to  be  the  materials  that  differ- 
ent manufacturers  use.  The  LMA,  for 
example,  is  made  from  latex.  A  com- 
pany that  works  with  latex,  that's  what 
they  do.  But,  that  has  limitations,  pri- 
marily because  of  high-pressure  cuffs. 
So,  the  market  is  limited  and  the  du- 
rability of  latex  tubes  is  limited.  Then 
you're  left  with  PVC  and  silastic.  Both 
of  those  materials  have  severe  struc- 


tural limitations.  PVC  is  good  for  cer- 
tain cuff  designs,  but  can't  do  the 
things  that  those  wonderful  cuffs  that 
the  Robertshaw  right-sided  tube  had. 
When  you  inflated  the  bronchial  cuff 
on  a  right-sided  Robertshaw  tube,  the 
orifice  that  was  built  within  that  cuff 
expanded  to  a  prodigious  size,  and  that 
made  that  tube  very  safe  and  easy  to 
place.  That  just  can't  be  reproduced  in 
any  other  material,  so  when  you  ap- 
proach other  manufacturers  to  try  to 
mimic  that  design,  they  can't.  So  the 
odd  designs  that  we  sometimes  .see 
are  crippled  versions  because  of  the 
type  of  material  used.  Lastly,  you  have 
silastic,  but  the  problems  of  silastic 
are  also  rather  large,  and  I  think  the 
Univent  tube  being  made  purely  from 
silastic  is  a  case  in  point.  It's  very  stiff 
and  difficult  to  place  and  control  the 
blocker. 

Thompson:  I  would  like  to  empha- 
size that  the  problems  you've  men- 
tioned are  also  a  major  problem  in 
pediatrics.  Any  new  device  that  looks 
like  it  has  potential  for  use  in  infants 
and  children  has  to  overcome  the  hur- 
dle of  relatively  low  demand.  As  a 
consequence,  many  devices  are  never 
scaled  down.  Double-lumen  tubes  for 
use  in  children  under  age  7  or  8  are 
virtually  nonexistent.  I  mentioned  our 
desire  to  have  some  kind  of  marker 
that  identifies  proper  tube  depth  in  the 
trachea,  but  to  date  it  does  not  appear 
to  be  an  issue  worth  dealing  with  for 
the  manufacturers. 

Stauffer:  I've  been  frustrated  for 
many  years  trying  to  figure  out  what 
kind  of  endotracheal  tube  a  patient  in 
the  intensive  care  unit  actually  has  in 
place.  By  the  time  they  arrive  in  the 
ICU,  they  have  already  been  intubat- 
ed— in  the  emergency  room,  in  the 
field,  at  another  hospital,  in  the  oper- 
ating room,  or  in  the  recovery  room. 
Then  the  endotracheal  tube  is  anchored 
with  thick  bands  of  adhesive  tape.  It's 
very  difficult  for  me  to  know  what 
kind  of  cuff  is  on  the  distal  end  of  the 
tube.  There's  no  labeling  on  the  prox- 


684 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Special  Purpose  Endotracheal  Tubes 


imal  end  to  indicate  the  type  of  cuff. 
The  tube  size  is  often  difficult  to  de- 
termine, as  well.  If  you  turn  the  15 
mm  adapter  over  and  shine  a  light  on 
it,  you  might  get  a  clue,  but  often  the 
size  markings  are  very  difficult  to  read. 
I  wish  the  tube  manufacturers  would 
help  us  out  in  that  regard  so  that  we 
know  what  kind  of  cuff  we"re  dealing 
with  and  have  an  easier  identification 
of  the  tube  size.  1  don't  know  if  any- 
body else  has  a  similar  concern,  but 
it"s  a  problem  for  me. 

Durbin:  1  would  point  out  that  cuff 
compliance  is  variable  between  man- 
ufacturers. A  highly  compliant,  high- 
volume  cuff,  means  very  different 
things  in  a  Riisch  tube  versus  one  from 
Mallinckrodt.  It  is  essential  to  know 
who  the  manufacturer  is  and  what  the 
specifications  are  for  tube  compo- 
nents. 

Pierson:  Ray  Ritz  should  probably 
have  made  this  comment,  because  he 
used  to  be  the  manager  in  our  hospi- 
tal, but  here's  one  anecdotal  report: 
Since  with  most  intubations  that  reach 
our  ICU  the  respiratory  therapists  have 
participated  as  an  assistant,  they  rou- 
tinely take  a  tongue  blade  and  write 
on  it  the  brand  and  size  of  the  tube, 
the  date  it  was  inserted,  and  the  depth 
of  insertion,  measured  at  the  teeth. 
They  then  tape  that  tongue  blade  to 
the  ventilator  so  that  that  information 
is  always  conveniently  available.  It's 
a  crude  system,  but  useful. 

StoIIer:  I'd  like  to  use  the  Journal 
Conference  as  a  forum  to  think  about 
other  "boutique-y"  tubes  that  would 
be  of  value  in  specific  niches,  such  as 
the  bronchoscopy  suite.  Having  placed 
the  bronchoscope  through  the  airway, 
one  then  incurs  a  problem  of  bleeding 


and  wants  to  intubate  the  patient  while 
using  the  bronchoscope  as  a  stylette, 
but  not  having  threaded  a  tube  over 
the  bronchoscope  in  advance.  So,  what 
we  need,  and  this  is  a  plea  to  manu- 
facturers, is  a  bivalved  tube — a  tube 
that  actually  opens  up  on  its  long  axis 
and  then  could  be  slid  over  the  bron- 
choscope already  in  the  airway  and 
then  closed  on  itself  and  slid  into  the 
airway — a  "zippered"  endotracheal 
tube.  Although  1  realize  it  would  be  a 
low-volume  item,  1  think  there  are  rare 
instances  in  which  it  would  be  ex- 
tremely helpful. 

Ritz:  Charlie,  I'm  a  little  confused 
about  your  pressure  volume  curves  for 
your  endotracheal  tubes.  How  were 
those  done? 

Durbin:  Cuffs  were  filled  with  ali- 
quots  of  air,  allowed  to  equilibrate  sev- 
eral minutes  at  room  temperature,  and 
the  cuff  pressure  recorded. 

Ritz:  So  that  was  just  the  maximum 
volume  it  took  to  fill  the  cuff  before 
you  got  pressure. 

Durbin:  It  was  a  deflated  cuff  in- 
flated stepwise  to  60  mL  and  then  back 
down  again. 

Ritz:  Right.  Because  it  would  seem 
like  the  best  cuff  would  be  one  that 
created  no  pressure  until  it  approached 
its  critical  volume.  The  compliance  of 
the  cuff  should  be  high  enough  so  that 
as  you  add  appropriate  volumes  while 
it's  actually  in  the  patient,  the  only 
pressure  that  you  measured  was  the 
tracheal  wall  contact  pressure.  I  really 
only  care  about  the  distending  pres- 
sure of  the  cuff  when  I've  overinflated 
the  cuff  or  if  I'm  using  a  low-volume 
high-pressure  cuff  So,  it  seems  to  be 


a  positive  attribute  to  say  1  put  5  cc  in 
a  cuff  and  it  didn't  have  any  pressure. 

Durbin:  That's  correct.  But,  you  also 
have  to  recognize  that  there  are  cuffs, 
such  as  in  the  double-lumen  endotra- 
cheal tubes,  where  that  bronchial  cuff  is 
very  small  and  is  also  potentially  very 
high  pressure.  There  are  the  red  rubber 
cuffs,  that  are  still  in  use  in  some  insti- 
tutions, where  the  pressure  you're  mea- 
suring in  your  connecting  tube  to  the 
pilot  balloon  is  not  a  reflection  of  the 
pressure  against  the  wall.  1  think  what 
you're  saying  is  that  you  want  one  that 
lies  against  the  wall  and  tells  you  what 
that  pressure  against  the  wall  is. 

Ritz:  Right.  It  seemed  to  me  from 
Dean's  [Hess|  presentation  earlier  that 
you  still  see  descriptions  in  textbooks 
of  minimal  occlusive  volume  tech- 
nique for  managing  cuffs.  And  as  Dean 
eloquently  pointed  out,  the  incidence 
of  aspiration  can  be  relatively  high 
with  that  technique.  I  don't  see  any 
reason  to  promote  minimal  occlusive 
volumes.  It  seems  like  the  cuff  pres- 
sure should  be  taken  up  to  25-30  cm 
H2O,  as  long  as  you're  talking  about 
tracheal  wall  contact  pressure.  You 
need  to  use  minimal  occlusive  vol- 
ume if  you're  using  low-volume  high- 
pressure  cuffs. 

Durbin:  That  is  correct.  But  those 
cuffs  do  exist.  There  are  devices  that 
have  them — the  percutaneous  trache- 
ostomy by  Portex  being  one  in  partic- 
ular, has  a  high-pressure,  low-volume 
design.  This  design  is  easier  to  insert. 
If  you're  talking  about  people  who  are 
inexperienced  at  inserting  them,  the 
low-profile  cuffs  offer  a  theoretical  ad- 
vantage. These  devices  do  exist. 


Respiratory  Care  •  June  1999  Vol  44  No  6 


685 


Methods  to  Avoid  Intubation 


Ray  Ritz  RRT 


Introduction 

Avoiding  Intubation  in  tlie  Acutely  111 

Fundamental  Approaches 

Positioning 

High-Flow  Oxygen  Therapy 
Continuous  Positive  Airway  Pressure 
Noninvasive  Positive  Pressure  Ventilation 
Heliox 
Long-Term  Options  in  Avoiding  Intubation 

Negative  Pressure  Ventilation 

Rocking  Beds  and  Pneumobelts 

Diaphragmatic  Pacemaking 

Secretion  Clearance 
Summary 

[Respir  Care  1999;44(6):686-699]  Key  words:  avoiding  intubation,  continuous 
positive  airway  pressure,  noninvasive  positive  pressure  ventilation,  heliox,  neg- 
ative pressure  ventilation,  diaphragmatic  pacing,  in-exsufflator 


Introduction 


Avoiding  Intubation  in  the  Acutely  111 


The  current  focus  on  maintaining  and  improving  the 
quality  of  health  care  while  reducing  costs  creates  a  strong 
impetus  to  avoid  invasive  approaches  to  ventilatory  sup- 
port. Evolving  noninvasive  approaches  offer  options  for 
management  of  acutely  and  chronically  ill  patients  without 
the  need  of  an  artificial  airway.  Techniques  like  helium- 
oxygen  therapy,  described  over  60  years  ago,  have  been 
updated  and  used  with  increasing  frequency  in  the  man- 
agement of  acute  asthma.  Secretion  clearance  therapy,  first 
reported  in  1953,  is  now  being  added  to  the  repertoire  of 
therapies  that  allow  improved  home  management  for  some 
neuromuscularly  impaired  patients,  and  may  help  reduce 
their  need  for  artificial  airways.  The  intubation  procedure 
and  artificial  airways  are  both  associated  with  a  variety  of 
risks  that  have  been  well  described  by  numerous  authors. 
The  best  way  to  avoid  these  complications  is  to  not  insert 
the  artificial  airway  in  the  first  place. 


Ray  Ril/  RRT  is  alTilialed  with  Respiratory  Care  Services.  Massachusetts 
(icncral  Hospital,  and  Harvard  Medical  School,  Boston.  Massachusetts. 

Correspondence:  Ray  Ritz  RRT.  Respiratory  Care  Services,  Ellison  401. 
Massachusetts  General  Hospital.  55  Fruit  Street.  Boston  MA  02114. 
E-mail:  nit/fr'^partners.org. 


Sophisticated  and  rapidly  deployable  code  response  sys- 
tems are  available  in  all  areas  of  every  hospital  to  respond 
to  unstable  patients.  Emergency  departments  and  intensive 
care  units  routinely  maintain  intubation  supplies  and  pro- 
vide around-the-clock  availability  of  staff  who  are  skilled 
at  intubation  and  airway  management.  Because  these  sys- 
tems are  so  efficient  and  readily  available,  they  have  often 
been  used  as  the  initial  responders  to  provide  stabilizing 
care  for  patients  who  meet  the  criteria  for  noninvasive 
techniques.  Often  this  results  in  the  placement  of  an  arti- 
ficial airway  and  the  initiation  of  mechanical  ventilation. 

Providing  a  response  system  modeled  after  these  sys- 
tems but  with  the  specific  goal  of  providing  noninvasive 
support  requires  a  well  organized,  multidi.sciplinary  ap- 
proach. A  successful  noninvasive  response  program  must 
include  the  following  critical  components: 

1.  well  defined  criteria  that  identify  which  patients  are 
most  likely  to  benefit  from  a  noninvasive  approach; 

2.  critical  equipment  and  resources  that  are  stationed  in 
the  areas  where  they  are  likely  to  be  needed; 

3.  appropriate  staff  training  and  skills  assessment  in 
noninvasive  management  techniques; 

4.  an  institutional  commitment  to  support  and  promote 
noninvasive  approaches. 


686 


Respiratory  Care  •  June  1 999  Vol  44  No  6 


Methods  to  Avoid  Intubation 


Fundamental  Approaches 

Patients  in  significant  respiratory  distress  may  continue 
to  deteriorate  until  endotracheal  intubation  is  required,  but 
appropriate  interventions  prior  to  that  point  may  stabilize 
the  patient's  physiology  and  avoid  the  need  for  an  artificial 
airway.  Basic  bedside  interventions  that  are  immediately 
available  can  be  rapidly  implemented  and  may  slow  the 
patient's  deterioration.  Optimal  body  positioning  and  care- 
fully adapted  oxygen  therapy  may  alleviate  much  of  the 
distress  until  other  more  effective  actions  are  prepared  and 
the  underlying  etiologies  are  resolved. 

Positioning 

Patient  position  can  dramatically  affect  lung  volumes 
and  work  of  breathing  (WOB).  The  functional  residual 
capacity  of  the  supine  patient  can  increase  as  much  as 
20-30%  when  they  are  moved  to  the  upright  sitting  posi- 
tion.' Going  from  sitting  to  lying  on  the  side  can  decrease 
functional  residual  capacity  by  as  much  as  15%.-  By  in- 
creasing the  resting  lung  volume,  the  airway  resistance  is 
reduced,  which  lowers  the  WOB,  and  oxygenation  may  be 
improved  by  alveolar  recruitment.  Patients  in  significant 
respiratory  distress  should  be  positioned  in  the  upright 
sitting  position  if  possible  in  order  to  maximize  thoracic 
volume  and  improve  ventilatory  mechanics.  The  fatigued 
patient,  in  addition  to  slumping  in  bed,  may  also  have 
difficulty  avoiding  soft  tissue  obstruction  of  the  airway. 
Positioning  of  the  head  and  mandible  to  maintain  a  patent 
airway  may  also  be  critical  to  restoring  adequate  ventilation. 

High-Flow  Oxygen  Therapy 

While  low-flow  oxygen  therapy  devices  are  readily  avail- 
able in  most  patient  care  areas  and  are  sufficient  for  the 
majority  of  clinical  situations,  they  may  be  inadequate  for 
those  patients  who  are  tachypneic  and  in  respiratory  fail- 
ure. Low-flow  systems  provide  a  modest  fraction  of  in- 
spired oxygen  (Fk,,)  during  quiet,  stable  breathing,  but  the 
actual  delivered  concentration  of  oxygen  varies  inversely 
with  the  patient's  minute  ventilation.  High-tlow  oxygen 
delivery  devices  employ  air-entrainment  to  accurately  mix 
oxygen  and  air  to  a  specific  concentration,  and  deliver  the 
output  at  a  flow  that  meets  or  exceeds  the  flow  meter 
setting.  The  limitation  of  airentrainment  devices  is  that  the 
higher  the  delivered  oxygen  concentration,  the  lower  the 
flow  output.' 

Although  the  output  of  a  high  flow  device  may  meet  or 
exceed  the  patient's  minute  ventilation,  the  more  impor- 
tant consideration  is  how  the  output  compares  with  the 
patient's  peak  inspiratory  flow.  The  data  in  Figure  1  were 
calculated  to  estimate  the  peak  inspiratory  flow  at  various 
respiratory  rate  and  tidal  volume  (Vp)  combinations. ■*  A 


140 

120 

"E 

100 

E 

80 

oc 

60 

u. 

a. 

40 

20 

-♦-20  -B-aS  -*-30  -♦-35  -•-40 

.y^^^^^^^^j^^^"^^ 

.^^^^^^^^^ 

1^^^^^"^ 

200     300     400     500     600     700     800     900 
VT(mL) 

Fig.  1.  Peak  inspiratory  flow  rates  (PIFR)  with  an  inspiratory-expi- 
ratory  ratio  of  1:1,  tidal  volumes  (Vy)  of  200-900  mL,  and  respira- 
tory rates  of  20,  25,  30,  35,  and  40  breaths  per  minute.  (Adapted 
from  data  In  Reference  4.) 


patient  with  a  respiratory  rate  of  30  b/min  and  Vy  of  500 
mL  who  requires  an  F|q^  of  0.50  will  achieve  a  peak  in- 
spiratory flow  of  more  than  70  L/min.  An  air  entrainment 
device's  maximum  flow  output  at  that  F|o,  setting  is  27-40 
L/min,  which  allows  significant  dilution  from  the  desired 
oxygen  level.  Foust  et  al  demonstrated  that  even  using  2 
jet  nebulizers  in  tandem  set  at  F,o,s  of  0.60  and  higher 
failed  to  provide  adequate  flows  to  meet  the  peak  inspira- 
tory flow  of  various  ventilatory  patterns,  resulting  in  lower 
than  desired  Fjo^s."* 

True  high-flow  devices  capable  of  providing  flows 
>  100  L/min  while  delivering  F,o,s  of  0.60  to  1.0  are 
commercially  available  or  can  be  assembled  with  compo- 
nents commonly  used  in  respiratory  care  departments. 
These  systems,  if  available,  may  be  useful  in  optimizing 
oxygen  therapy,  but  they  require  more  time  than  desired  to 
set  up.  The  key  is  to  have  these  devices  readily  available 
and  prepared  for  use.  In  many  situations,  it  is  more  effi- 
cient to  use  a  nonrebreather  mask  connected  to  a  0-15 
L/min  flow  meter  set  at  "flush."  This  will  provide  a  flow 
of  >  40  L/min  of  100%  oxygen,  which  is  clearly  more 
flow  than  is  available  from  an  air  entrainment  device  at  the 
same  F|o,- 

Continuous  Positive  Airway  Pressure 

First  described  in  1936,'^''  continuous  positive  airway 
pressure  (CPAP)  has  been  used  in  the  treatment  of  pul- 
monary edema,  chronic  obstructive  pulmonary  disease 
(COPD)  and  other  clinical  presentations  where  hypoxemia 
is  not  reversed  by  aggressive  oxygen  therapy.  The  most 
common  current  use  of  CPAP  is  in  the  treatment  of  ob- 
structive sleep  apnea  (OS A).  Used  at  modest  levels  (4-6 
cm  H2O),  it  is  effective  at  clearing  soft  tissue  obstructions 
that  create  apnea.  If  the  OSA  is  accompanied  by  chronic 
hypoventilation  and  increased  arterial  carbon  dioxide  ten- 
sion (Paco,)'  inspiratory  pressure  support  may  be  needed 


Respiratory  Care  ♦  June  1999  Vol  44  No  6 


687 


Methods  to  Avoid  Intubation 


in  addition  to  CPAP.  A  less  desirable  but  definitive  method 
of  preventing  OSA  is  the  placement  of  a  tracheostomy. 
Besides  being  able  to  prevent  obstructive  apnea,  CPAP 
can  increase  functional  residual  capacity,  improve  atelec- 
tasis, reduce  right  to  left  shunt,  and  reduce  WOB  by  in- 
creasing lung  compliance. 

CPAP  also  can  reduce  the  WOB  caused  by  air  trapping 
and  endogenous  positive  end-expiratory  pressure  (auto- 
PEEP),  since  it  allows  for  the  equilibration  of  airway  pres- 
sure with  the  pressure  present  at  the  alveolar  lung  region.^ 
For  this  reason  it  has  been  considered  as  an  adjunct  in  the 
treatment  of  acute  asthma.  While  not  providing  inspiratory 
assistance,  and  therefore  not  ideally  suited  for  the  treat- 
ment of  hypercarbia,  CPAP  via  oronasal  mask  has  been 
shown  to  be  successful  in  reversing  hypoxemia  and  avoid- 
ing intubation  in  acute  cardiogenic  pulmonary  edema**  ". 
When  compared  to  bi-level  pressure  ventilation  in  acute 
pulmonary  edema,  CPAP  was  slower  to  improve  both  ven- 
tilation (as  measured  by  Paco,)  ^nd  vital  signs  (systolic 
and  mean  blood  pressure),  but  CPAP  had  a  lower  myo- 
cardial infarction  rate:  31%  to  71%  in  that  patient  popu- 
lation.'- It  is  unclear  why  the  rate  of  myocardial  infarction 
was  higher  with  bi-level  pressure  ventilation.  It  may  have 
been  related  to  the  greater  early  reduction  of  systemic 
blood  pressure.  The  possibly  higher  intrathoracic  pressures 
associated  with  bi-level  pressure  ventilation  may  have  fur- 
ther reduced  venous  return,  which  in  turn  may  have  re- 
duced myocardial  perfusion.  This  topic  needs  further  study 
to  determine  which  therapy  (CPAP  vs  bi-level  pressure 
ventilation)  is  best  suited  for  acute  pulmonary  edema.  We 
currently  use  CPAP  as  our  initial  and  more  conservative 
approach  in  these  patients,  but  bi-level  pressure  ventilation 
may  be  used  if  hypercarbia  is  a  primary  concern,  and  if  the 
patient  is  carefully  monitored. 

There  are  numerous  apparatus  available  that  can  pro- 
vide mask  CPAP.  Simple  constant  flow  generators  that 
deliver  stable  F,o,s  between  0.21  and  1.00,  regardless  of 
back  pressure,  are  available  commercially  or  can  be  as- 
sembled from  commonly  available  supplies.  The  constant 
flow  generator  CPAP  systems  require  a  special  mask  with 
valves  to  ensure  unidirectional  gas  flow  to  prevent  re- 
breathing,  and  the  PEEP  level  is  controlled  by  a  valve 
placed  at  the  expiratory  outlet.  Bi-level  pressure  ventila- 
tors easily  provide  CPAP,  but  most  lack  the  ability  to 
precisely  control  the  F,o,-  Oxygen  can  be  bled  into  the  gas 
stream,  but  the  actual  concentration  will  vary  as  the  gas 
flow  from  the  bi-level  pressure  generator  changes,  and 
high  F|Q^s  are  difficult  to  achieve.  While  all  these  devices 
and  others  not  described  can  provide  CPAP,  when  treating 
the  unstable  patient,  speed  and  flexibility  are  critical  to 
successfully  avoid  intubation.  For  that  reason  it  may  be 
more  efficient  to  begin  with  a  critical  care  ventilator.  A 
critical  care  ventilator  can  provide  mask  CPAP  at  a  stable 
F|o,,  allows  for  easy  adjustment  of  the  PEEP  level,  offers 


a  variety  of  monitored  parameters,  and  inspiratory  assis- 
tance can  be  added  if  desired.  If  the  attempt  at  avoiding 
intubation  fails,  it  can  be  used  for  invasive  ventilation. 

Noninvasive  Positive  Pressure  Ventilation 

For  the  last  10  years,  the  most  widely  applied  and  suc- 
cessful method  to  avoid  intubation  has  been  noninvasive 
positive  pressure  ventilation  (NPPV).  Both  controlled  and 
uncontrolled  studies,  listed  in  Table  1,  have  reported  re- 
sults on  patients  with  diagnoses  that  include  COPD,  con- 
gestive heart  failure,  pneumonia,  postextubation  failure, 
asthma,  chest  wall  disease,  cystic  fibrosis,  acute  respira- 
tory distress  syndrome,  postoperative  respiratory  failure, 
pulmonary  fibrosis,  and  restrictive  lung  disease.  The  meth- 
ods of  NPPV  varied  and  included  pressure  ventilation  or 
volume  ventilation  modes,  full  face  masks  or  nasal  masks, 
and  critical  care,  home  care,  or  bi-level  positive  airway 
pressure  ventilators.  The  pooled  data  indicate  a  74%  suc- 
cess rate  at  reducing  mortality  and  avoiding  intubation. 
Figure  2  summarizes  the  data  from  6  studies'-''  '**  on  intu- 
bation rates  of  patients  receiving  NPPV  versus  standard 
therapy;  most  of  these  studies  found  a  significantly  lower 
intubation  rate  with  NPPV.  Kramer  et  al'^  found  that  non- 
COPD  patients  did  not  seem  to  benefit  from  NPPV,  nor 
did  patients  without  carbon  dioxide  retention,  studied  by 
Wysocki"*  (Fig.  3).  This  would  indicate  that  respiratory 
failure  secondary  to  muscle  fatigue  may  respond  better  to 
NPPV  than  if  the  failure  is  caused  by  pneumonia,  acute 
respiratory  distress  syndrome,  congestive  heart  failure,  or 
other  parenchymal  lung  diseases. 

When  designing  an  NPPV  response  program,  patient 
selection  is  critical.  The  inclusion  and  exclusion  criteria 
listed  in  Fig.  4  reflect  commonly  accepted  patient  selection 
criteria.  The  next  issue  is  the  selection  NPPV  equipment. 
The  American  Respiratory  Care  Foundation's  consensus 
statement  on  NPPV  recognizes  2  levels  of  NPPV.  Type-1 
support  is  defined  as  NPPV  that  provides  life  sustaining 
support  that,  if  terminated,  could  be  life  threatening,  ver- 
sus Type-2  support,  which  is  beneficial  but  interruption  is 
not  life  threatening.'"^  Type-1  support  devices  differ  from 
Type-2  devices  in  that  they  include  the  ability  to  provide 
a  mandatory  breathing  rate,  precise  control  of  F,o,,  avail- 
ability of  PEEP  up  to  15  cm  H^O,  and  disconnect  and 
power  loss  alarms.  For  hospital  application,  the  critical 
care  ventilator  meets  or  exceeds  all  the  requirements  of  a 
Type-1  device.  Once  the  patient  is  stable  and  no  longer 
requires  aggressive  support,  he  or  she  can  be  switched  to 
a  Type-2  device.  These  are  commonly  bi-level  pressure 
generators  designed  for  home  use. 

One  of  the  more  challenging  and  vital  aspects  of  NPPV 
is  the  ability  to  choose  the  correct  patient  interface.  It  must 
minimize  leaks,  provide  adequate  patient  comfort,  and  not 
cause  skin  breakdown.  Many  patients  are  uncooperative  or 


688 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Methods  to  Avoid  Intubation 


Table  1 .      Summary  of  Studies  on  Intubation  Rates 


Author 

Year 

Number  of 
Patients 

Intubation 
Avoided 

Percent 

Controlled/ 
Uncontrolled 

Meduri'"' 

1989 

10 

7 

70 

U 

Brochard'^ 

1990 

13 

12 

92 

C 

Carrey-" 

1990 

3 

3 

100 

u 

Elliott" 

1990 

6 

5 

83 

u 

Chevrolet'''' 

1991 

6 

3 

50 

u 

Hodson'"' 

1991 

6 

5 

83 

u 

Marino"" 

1991 

13 

9 

69 

u 

Meduri" 

1991 

18 

13 

72 

u 

Pennock'- 

1991 

29 

22 

76 

u 

Benhamou" 

1992 

30 

18 

60 

u 

Foglio"-' 

1992 

25 

24 

96 

u 

Udwadia" 

1992 

22 

18 

82 

u 

Bott'" 

1993 

30 

26 

87 

C 

Conway" 

1993 

10 

7 

70 

u 

Fernandez"** 

1993 

12 

9 

75 

u 

Restrick™ 

1993 

14 

13 

93 

u 

Vitacca'" 

1993 

29 

24 

83 

c 

Wysocki"" 

1993 

17 

8 

47 

u 

Lapinsky"' 

1994 

2 

2 

100 

u 

Meduri"- 

1994 

11 

7 

64 

u 

Pennock"' 

1994 

110 

84 

76 

u 

Soo  Hoo" 

1994 

14 

7 

50 

u 

Tognet"' 

1994 

15 

6 

40 

u 

Ambrosino"'' 

1995 

59 

46 

78 

u 

BroL-hard" 

1995 

43 

32 

74 

c 

Chaing" 

1995 

19 

11 

58 

u 

Confalonieri"' 

1995 

28 

18 

64 

c 

Kramer'" 

1995 

16 

11 

69 

c 

Pollack"'* 

1995 

50 

43 

86 

u 

Sacchetti'*'^' 

1995 

22 

20 

91 

u 

Wysocki"* 

1995 

21 

12 

57 

c 

Meduri"' 

1996 

158 

112 

71 

u 

Meduri"" 

1996 

17 

16 

94 

u 

Patrick"' 

1996 

11 

8 

73 

u 

Totals 

889 

661 

745^ 

refuse  therapy  due  to  improper  mask  fit.  A  full  face  masic 
is  commonly  preferred  in  the  early  treatment  of  acute  re- 
spiratory failure  (ARF),  since  the  fatigued  or  somnolent 
patient  may  have  difficulty  closing  his  or  her  mouth,  which 
results  in  a  gross  air  leak.  This  mouth  leak  reduces  the 
efficiency  of  the  therapy  and  increases  the  patient's  dia- 
phragmatic activity.-"  Some  claustrophobic  patients  may 
only  tolerate  a  nasal  mask.  When  choosing  which  full  face 
mask  to  stock  for  NPPV.  the  answer  is  simple — as  many 
types  and  sizes  as  you  can  find.  A  1995  list  of  available 
NPPV  masks  counted  1 8  manufacturers  who  made  a  total 
of  1 1 1  masks  in  various  styles  and  sizes.-'  Although  it  is 
not  necessary  to  have  all  of  them,  we  found  the  best  so- 
lution was  to  keep  boxes  (Fig.  5)  with  a  wide  variety  of 
masks  and  accessories  stationed  in  critical  areas  (eg,  in  the 


emergency  room  and  medical  intensive  care  unit).  This 
was  important  for  efficiency  and  also  because  changing 
mask  styles  or  sizes  periodically  improves  patient  comfort 
and  cooperation. 

Once  the  correct  mask  is  chosen  and  the  procedure  is 
explained  to  the  patient,  NPPV  can  be  applied  in  stepwise 
fashion  to  acclimate  the  patient  to  the  system.  Starting 
with  a  low  PEEP  setting  and  inspiratory  pressures  of  5-10 
cm  HiO,  the  patient  (or  caregiver)  can  manually  hold  the 
mask  in  place  for  several  breaths.  Once  synchronous  ven- 
tilation is  developed,  the  mask  can  be  secured  with  the 
appropriate  head  strap.  Attach  the  head  strap  cautiously  so 
as  to  avoid  applying  excessive  pressure  to  the  face.  If  the 
mask  must  be  over-tightened  to  eliminate  gross  leaks,  a 
different  size  or  type  of  mask  should  be  tried.  Once  the 
mask  is  strapped  in  place,  the  inspiratory  and  expiratory 
pressures  should  be  adjusted  according  to  Figure  4.  Peak 
airway  pressures  greater  than  20-25  cm  H^O  are  rarely 
needed.  In  stable  COPD,  auto- PEEP  averages  2.4  ±  1.6 
cm  HjO.--  During  acute  exacerbations,  the  optimal  level 
of  PEEP  may  be  5-7.5  cm  HjO,  since  auto-PEEP  levels  in 
this  patient  population  are  generally  6.5  ±  2.5  cm  H^O. ''■'-'' 
Applied  at  a  slightly  lower  level  than  total  PEEP,  applied 
PEEP  generally  will  not  worsen  the  air  trapping,  but  will 
minimize  the  WOB. 

Monitoring  the  patient's  response  and  tolerance  is  a 
critical  aspect  of  NPPV.  If  successful,  P„co,  should  de- 
crease within  1-2  hours. -^  Within  this  same  period  there 
should  be  a  decrease  in  respiratory  rate,  increase  in  V^, 
and  the  patient  should  notice  a  marked  improvement  in 
dyspnea.  In  order  to  achieve  this  increased  Vj  and  reduced 
respiratory  rate,  it  may  be  useful  to  apply  inspiratory  pres- 
sure levels  as  high  as  20  cm  HiO.'"*  If  patient-ventilator 
dyssynchrony  occurs,  the  cause  should  be  determined  and 
resolved.  It  may  be  due  to  inadequate  applied  PEEP  on  a 
patient  with  air  trapping,  which  makes  triggering  inspira- 
tion difficult.  Other  causes  include  inadequate  sedation, 
excessive  mask  leak,  and  anxiety.  Frequent  coaching  and 
adjustment  of  the  mask  and  ventilator  may  be  required 
to  assure  success  with  NPPV.  Due  to  the  monitoring  re- 
quirements, NPPV  should  be  done  initially  in  an  intensive 
care  unit. 

A  common  observation  related  to  NPPV  is  the  increased 
time  required  for  patient  care  during  the  first  several  hours. 
Kramer'"  assessed  the  bedside  time  required  for  NPPV 
versus  patients  receiving  standard  care,  and  found  that 
during  the  first  8  hours  there  was  an  increased  amount  of 
bedside  activity  for  patients  receiving  NPPV.  During  the 
second  8  hours,  the  non-NPPV  patients  required  more  at- 
tention. When  both  8-hour  periods  are  combined,  there 
was  no  significant  difference  between  the  control  group 
and  the  NPPV  group.  Given  the  significant  reduction  in 


Respiratory  Care  •  June  1999  Vol  44  No  6 


689 


Methods  to  Avoid  Intubation 


Brochard 
1990 


Vitacca 
1993 


Brochard 
1995 


Kramer 
1995 


Wysocki 
1995 


Confalonieri 
1996 


Fig.  2.  Percent  of  patients  intubated  in  6  controlled  studies  (Brochard, ^^  Vitacca,^"  Brochard,''^ 
Kramer,^''  Wysocki, ^^  Confalonieri,"^  using  noninvasive  positive  pressure  ventilation  (NPPV)  to 
treat  ARF.  (Adapted  from  data  in  Reference  65.) 


100 


Kramer 
COPD 


Kramer 
non-COPD 


Wysocki 
PaC02  >  45 


Wysocki 
PaC02  <  45 


Fig.  3.  The  effect  of  noninvasive  positive  pressure  ventilation  (NPPV)  on  chronic  obstructive  pul- 
monary disease  (COPD)  versus  non-COPD  and  patients  vi^ith  and  without  CO2  retention  during 
acute  respiratory  failure.  (Adapted  fom  data  in  Reference  65,  using  the  studies  of  Kramer^'  and 
Wysocki.'^) 


mortality  and  length  of  intensive  care  unit  and  hospital 
stay  that  results  from  avoiding  intubation  by  employing 
NPPV,  the  increased  early  work  requirement  is  clearly 
worth  the  investment.  Weaning,  on  the  other  hand,  be- 
comes much  easier.  Some  patients  require  a  slow,  sequen- 
tial reduction  in  support,  much  the  same  as  with  invasive 
ventilation,  except  that  there  are  no  questions  or  issues 


regarding  extubation.  Some  patients  can  participate  in  the 
process;  once  they  are  recovered  from  their  fatigue,  many 
simply  remove  the  mask. 

Because  of  the  complexity  of  NPPV,  staff  must  be  spe- 
cifically trained  in  its  techniques  and  requirements.  Phy- 
sicians, nurses,  and  respiratory  therapists  must  understand 
selection  criteria  so  that  candidates  can  be  recognized 


690 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Methods  to  Avoid  Intubation 


MGH  NPPV  Guidelines 


Inclusion  Criteria: 

•Acute  hypercapnic  respiratory  failure  (2  or  more) 
-  severe  worsening  dyspnea  t 

-respiratory  rate  >  25/min.  t 

-use  of  accessory  muscles  /  abdominal  paradox    c 
-pH  <  7.35  and  PaCO^  >  45  mm  Hg 

•Clinical  impression  of  impending  intubation 


Yes 


Monitor: 

•Patient  comfort 

•Level  of  dyspnea 

'Respiratory  rate  and  tidal  volume 

•Heart  rate  and  blood  pressure 

•SpO, 

'Accessory  muscle  use  or  respiratory  paradox 

•Patient-ventilator  synchrony 

•Mask  leak 

•ABG  {30  -  60  min  after  acclimation) 


I 


Adjustments  to  Improve  Patient  Compliance: 

'Coaching 

'Mask  fit  (size  &  nasal  versus  full  face  mask) 

'Ventilator  mode  (PSV  vs  PCV  vs  VCV) 

'Inspiratory  and  expiratory  pressure  levels 

'FiOj 

'Sedation 

'Continuous  vs  intermittent  use 

•Bronchodilator  therapy 


Transfer  to  ICU: 

'Evaluate  patient  for  transport  without  NPPV: 
'respiratory  rate  <  20/min 
'dyspnea/paradox  relieved 
'Vt->  7mL/kg  on  PSV  <  15  cm  H;0 
•Standard  transport  monitoring  (EGG,  SpO;) 
'Transport  with  RRT,  RN  &  MD  if  unstable 


12-H  Rest  on  NPPV  if  Tolerated 


Nursing/Respiratory  Care  Considerations: 

•Standard  bed 

'Monitor  for  signs  of  gastric  distension 

'Bronchodilators  via  SVN/ventilator 

'Assess  mask  fit  (leaks,  dry  eyes,  skin  breakdown) 

'Out  of  bed  to  chair  if  tolerated 

'NPO  first  24  h 


T 


Exclusion  Criteria 

'Respiratory  arrest 

'Unable  to  cooperate 

'Need  for  airway  protection  (coma,  seizure,  vomiting) 

•Hypotension  (Systolic  blood  pressure  <  90  mm  Hg) 

'Recent  facial,  esophageal  or  gastric  surgery/trauma 

•Cardiorespiratory  instability/  Ml/cardiogenic  pulmonary  edema 


No 


Ves 


Initial  Ventilator  Settings: 

•Critical  care  ventilator 

•Full  face  mask 

•Pressure  support  ventilation 

•Titrate  pressure  level  to  patient  comfort 

•respiratory  rate  <  25/min;  V^  7  - 10  mL/kg 
•use  of  accessory  muscle/paradox 

•Limit  PSV  to  <  20  cm  HjO 

•PEEP  =  0  cm  HjO 

•Titrate  FiO;  for  SpOj  >  90% 


Failure  Criteria: 

•Hemodynamic  instability 
•Decreased  mental  status 
•Respiratory  rate  >  35/min 
'Worsening  respiratory  acidosis 
•Inability  to  maintain  SpO;  >  90% 
•Inability  to  tolerate  mask 
•Inability  to  manage  secretions 
•Patient  preference 


No 


Yes 

— ► 


Consider 
Intubation 


Unable  to  Transport  Safely 


Transfer  to  Floor 


Wean  as  Tolerated: 

•PSV  target  of  10  cm  HjO 

•wean  by  2  cm  Hp/hr  if  V,^  >  7  mL/kg 
•FiOj  target  of  0.40 

•wean  by  pulse  oximetery  if  SpO;  >  90% 


No 


I 


Free  from  NPPV  for  24  H  Without  Fatigue 


Yes 


Trials  Off  NPPV  as  Tolerated 


1 


Monitor  for  Signs  of  failure:  Resume  NPPV  if: 

•Respiratory  rate  >  25/min 
•Worsening  dyspnea 
•Increased  use  of  accessory  muscles 
•Patient  request 


Fig.  4.  Massachusetts  General  Hospital  noninvasive  positive  pressure  ventilation  (NPPV)  guidelines. 


quickly.  Specific  orientation  to  mask-fit  options  is  neces- 
sary because  much  of  the  success  of  NPPV  rehes  on  the 
interface  fitting  correctly  and  comfortably.  Ventilator  ad- 


justments must  be  made  quickly,  with  a  goal  of  unloading 
the  respiratory  muscles  and  achieving  good  patient-venti- 
lator synchrony.  Teamwork  between  the  nurse  and  the 


Respiratory  Care  •  June  1999  Vol  44  No  6 


69! 


Methods  to  Avoid  Intubation 


Fig.  5.  A  well  stocked  noninvasive  positive  pressure  ventilation 
(NPPV)  interface  box  contains  a  variety  of  types  and  sizes  of  full 
face  masks,  nasal  masks,  CPAP  equipment,  and  other  useful  ac- 
cessories to  facilitate  proper  mask  fit. 


respiratory  therapist  is  essential  in  order  to  provide  the 
level  of  monitoring  and  coaching  required  for  success. 

Heliox 

Patients  with  acute  asthma  or  upper  airway  obstruction 
may  require  intubation  and  mechanical  ventilation  because 
of  the  excessive  resistive  component  to  their  WOB.  Intu- 
bation is  usually  considered  when  there  is  worsening  hy- 
percarbia,  increasing  muscle  fatigue,  and  marked  air  trap- 
ping. An  intervention  that  reduces  the  resistance  to  air 
flow  through  the  central  and  upper  airways  may  signifi- 
cantly reduce  this  work  and  improve  ventilation  until  phar- 
macologic therapy  either  relieves  the  bronchospasm  or  re- 
duces the  inflammation  of  the  larynx  or  trachea  that  is  the 
underlying  cause  of  the  ARF.  As  early  as  1934,24-27  j^g. 
Hum  and  oxygen  mixtures  (heliox)  were  shown  to  relieve 
dyspnea  in  these  patients. 

Helium/oxygen  mixtures  are  less  dense  than  room  air, 
yet  slightly  more  viscous.  Figure  6  shows  the  density  and 
kinematic  viscosity  of  various  helium  and  oxygen  mix- 
tures. The  lower  density  of  heliox  increases  laminar  flow 
in  the  central  and  upper  airways,  where  flow  is  generally 
turbulent.  In  the  peripheral  airways  (generations  1 1  through 
20),  flow  is  much  lower  and  therefore  predominately  1am- 
inar.^**  In  the  laminar,  low-flow  environment  found  in  the 
peripheral  airways,  the  higher  viscosity  of  helium  may 
actually  increase  the  resistive  component  of  WOB.  When 
considering  a  patient  for  heliox  therapy,  it  is  prudent  to 
assess  the  site  of  increased  airway  resistance.  Patients  with 
COPD  or  small  airway  disease  may  not  respond  to  heliox, 
since  much  of  their  airway  resistance  occurs  in  the  periph- 
eral regions  of  the  lung.  Conditions  that  are  more  likely  to 
respond  to  heliox  therapy  are  those  of  the  central  and 


upper  airway,  including  obstruction  secondary  to  postex- 
tubation  stridor,29-3o  croup,"  and  obstructive  masses  and 
swelling. -'2-''5 

Heliox  may  not  always  improve  minute  ventilation  and 
reduce  airway  resistance  in  asthma.  Early  in  an  asthma 
flare,  the  primary  site  of  airway  obstruction  is  in  the  cen- 
tral airways,  where  heliox  is  effective.^*-^^  If  the  flare  has 
persisted  for  96  hours  or  more,  the  benefit  of  heliox  may 
be  reduced,-^'  because  the  peripheral  airways  can  become 
clogged  with  secretions  and  edema.  The  decision  tree  in 
Figure  7  describes  a  step-wise  treatment  plan  for  asthma 
patients,  which  includes  the  use  of  heliox  for  those  with 
severe  asthma.'*" 

When  using  heliox  to  avoid  intubation,  it  is  important  to 
be  able  to  provide  aggressive  aerosol  therapy  without  in- 
terrupting the  helium  delivery  or  diluting  the  inspired  he- 
lium concentration  with  gas  from  the  nebulizer.  To  accom- 
plish this,  a  nonrebreathing  mask  can  be  modified  by  placing 
a  Y-piece  between  the  reservoir  bag  and  the  mask,  and 
attaching  a  nebulizer  to  the  mask,  as  shown  in  Figure  8. 
Two  oxygen  flow  meters  can  be  attached  to  a  heliox  cyl- 
inder (Fig.  9);  one  flow  meter  connects  to  the  reservoir  bag 
and  is  set  at  a  flow  that  prevents  the  bag  from  completely 
deflating  on  inspiration.  The  other  flow  meter  is  connected 
to  the  nebulizer,  and  should  be  set  at  5-6  L/min,  as  ob- 
served on  the  flow  setting.  Since  the  flow  meters  are  cal- 
ibrated to  the  density  of  oxygen,  an  80%  helium  mixture 
will  be  incorrect  by  a  factor  of  1.8.  In  other  words  5-6 
L/min  displayed  is  an  actual  flow  of  9-1 1  L/min  of  heliox. 
This  flow  appears  to  improve  the  function  of  the  nebulizer 
to  deliver  albuterol  while  using  heliox  as  the  driving  gas."" 

The  effectiveness  of  heliox  to  produce  laminar  flow  is 
also  related  to  the  amount  of  helium  present  in  the  mixture. 
Medical  heliox  is  most  commonly  obtained  in  concentra- 
tions of  80%  helium  and  20%  oxygen.  This  mixture  is 
convenient,  since  it  provides  the  highest  possible  level  of 
helium  without  delivering  sub-ambient  levels  of  oxygen.  If 
additional  oxygen  is  required,  it  can  be  blended  in,  but  the 
lower  the  concentration  of  helium,  the  less  effective  it  is  at 
reducing  airway  resistance.  In  order  to  achieve  the  maxi- 
mum effect  from  heliox,  the  helium  concentration  should 
not  be  reduced  below  60-70%.  Fortunately,  patients  with 
acute  asthma  and  upper  airway  obstruction  generally  have 
adequate  oxygenation,  and  initial  hypoxemia  is  more  a 
function  of  inadequate  ventilation.  Once  the  heliox  is  ad- 
ministered, ventilation  and  oxygenation  are  improved  and 
air  trapping  is  reduced.  If  additional  oxygen  is  required 
when  providing  heliox  with  the  modified  nonrebreathing 
mask  shown  in  Figure  8,  the  easiest  method  is  to  use  a 
nasal  cannula  under  the  mask  at  a  flow  of  1-3  L/min, 
titrated  to  achieve  an  acceptable  pulse  oximetry-measured 
oxygen  saturation. 

While  heliox  does  not  actually  resolve  the  underlying 
problem,  it  does  buy  time  until  appropriate  pharmaceutical 


692 


Respiratory  Care  •  June  1999  Vol  44  No  6 


1.600 


Methods  to  Avoid  Intubation 


800 


CM 

o 

o 

o 

o 

o 

o 

O 

O) 

CO 

h- 

CO 

in 

■>!■ 

o 

o 

o 

o 

o 

ss 

CM 

CO 

■<1- 

If) 

CO 

o 

o 

Helium/Oxygen  Percentage 

Fig.  6.  The  density  and  kinematic  viscosity  of  various  tielium  and  oxygen  mixtures  (heliox). 


therapy  becomes  effective.  In  our  experience,  when  heliox 
is  required,  it  is  utilized  for  12-24  hours.  In  the  case  of 
asthma,  this  allows  time  for  j3-agonist  and  steroid  therapy 
to  be  implemented.  Aggressive  ^-agonist  therapy  is  ap- 
propriate, and  includes  both  continuous  aerosolized  albu- 
terol,-*2  •*\  and  high  dose  albuterol.-"'  If  postextubation  stri- 
dor does  not  improve  after  24  -36  hours  of  therapy  designed 
to  reduce  upper  airway  inflammation,  the  patient  should  be 
reassessed  for  webbing  of  the  vocal  cords  or  other  causes 
that  might  require  reintubation  or  surgical  treatment.  A 
24-hour  course  of  heliox  to  the  nonintubated  patient  will 
generally  consume  3-4  H  cylinders.  In  our  emergency 
department,  we  maintain  2  heliox  cylinders  with  preas- 
sembled  nonrebreathing  masks  (modified  as  shown  in  Fig- 
ure 8)  to  facilitate  rapid  deployment.  This  minor  modifi- 
cation has  greatly  improved  the  success  of  our  heliox 
program,  because  equipment  assembly  time  delays  had 
been  resulting  in  more  frequent  intubations. 

Unfortunately,  not  all  studies  were  able  to  demonstrate 
an  improvement  as  a  result  of  heliox  therapy.**'''"*  If  effec- 
tive, like  NPPV,  there  should  be  several  early  indications 
of  benefit.  If  the  heliox  flow  is  adequate,  there  should  be 
a  distinct  change  in  the  sound  of  the  patient's  voice.  He- 
liox produces  a  distinct  high-pitched  "cartoon"-like  voice. 
If  this  voice  change  does  not  occur,  the  total  flow  of  heliox 
may  be  inadequate  to  meet  the  patient's  inspiratory  flow 
demand  or  the  concentration  may  be  too  low  because  of 
excessive  dilution  with  supplemental  oxygen.  Shortly  after 
administration,  the  patient  should  experience  reduction  in 
respiratory  rate,  reduction  in  accessory  muscle  use,  and 
improvement  in  dyspnea.  The  latter  may  be  the  most  im- 
portant and  sensitive  indication  of  successful  heliox  ther- 
apy. There  will  also  be  a  reduction  in  pulsus  paradoxus. 


which  is  indirectly  related  to  inspiratory  muscle  work.'* 
The  monitoring  of  Paco,  can  provide  some  quantification 
of  increased  minute  ventilation  and  precisely  define  the 
degree  of  heliox  effectiveness,  but  this  may  not  be  re- 
quired if  an  overall  improvement  in  breathing  is  evident. 

Long-Term  Options  in  Avoiding  Intubation 

Negative  Pressure  Ventilation 

The  application  of  negative  pressure  to  the  thorax  and 
abdomen  was  the  first  method  used  to  provide  continuous 
artificial  ventilation.  Crude  versions  of  "tank"  ventilators 
were  produced  as  early  as  1832,''''  but  the  use  of  negative 
pressure  ventilation  (NPV)  to  treat  both  acute  and  chronic 
respiratory  failure  did  not  become  widespread  until  the 
1920s.  In  the  early  1950s,  invasive  positive  pressure  ven- 
tilation via  tracheostomy  provided  higher  survival  rates 
over  NPV  because  of  the  reduced  rate  of  aspiration  asso- 
ciated with  the  cuffed  airway.™  Still,  until  the  mid-1980s, 
when  mask  ventilation  became  popular,  NPV  was  the  most 
common  method  of  noninvasively  treating  chronic  respi- 
ratory failure. 

The  iron  lung,  although  effective  and  used  extensively 
during  the  poliomyelitis  epidemics,  had  several  notable 
drawbacks.  It  requires  the  patient  to  lie  supine  in  an  en- 
closed cylinder,  which  limits  access  for  care.  It  is  large  and 
heavy,  which  limits  patient  mobility.  Iron  lungs  and  their 
next  generation,  the  Portalung  (Respironics,  Pittsburgh, 
Pennsylvania),  a  smaller  and  lighter  version,  are  available 
today  but  are  infrequently  used. 

A  more  common  apparatus  today  for  providing  NPV  is 
the  chest  shell  or  cuirass.  Using  a  turtle  shell-shaped  dome 


Respiratory  Care  •  June  1999  Vol  44  No  6 


693 


Methods  to  Avoid  Intubation 


Exacerbation  of  Asthma 


T 


1 .  Aerosolized  B-agonist  every  0.5-1 .0  h  or 
continuously 

2.  Methylprednisolone  1-2  mg/kg  I.V.,  then 
0.5-2.0  mg/kg  every  6  h 


1-2  hours 


1.  Comfortable? 

2.  Respiratory  rate  <  25  breath/min? 
Is  patient:                3.  Pulsus  paradoxus  <  1 5  mm  Hg? 

4.  Peak  flow  >  60%  predicted? 

5.  Pco2  =  35-40  mm  Hg? 


Yes 


Consider  discharge  on  oral 
steroids  &  B-agonist  inhalers 
with  a  follow-up  appointment 


No 


Consider  adding: 

1 .  Theophylline 

2.  Ipratropium  or  glycopyrrolate  aerosols 

3.  Admission  for  treatment 


Is  patient: 


1.  Uncomfortable? 

2.  Respiratory  rate  >  30  breaths/min 

3.  Pulsus  paradox  >  15  mm  Hg? 

4.  Peak  flow  <  200  L/min 

5.  pH<7.3 

Consider  ICU  Admission 


i 


If  patient  is  stable, 

consider  70-80%  helium  breathing. 

Obtain  blood  gas  and  vital  signs 

after  10-15  minutes 


If  no  improvement 


Continue  Therapy  and 


Consider  intubation  for 

1.  pH<7.25 

2.  Pulsus  decreasing  during  patient  worsening 

3 .  Peak  flows  decreasing  despite  therapy 

4.  Respiratory  rate  >  35  breaths/min 


Intubate,  Mechanically  Ventilate 


Fig.  7.  Acute  asthma  pathway  that  includes  the  use  of  helium  and  oxygen  mixtures  (heliox)  for  those  patients 
in  which  intubation  is  considered. 


that  covers  the  anterior  surface  of  the  chest  and  abdomen, 
negative  pressure  is  applied  to  the  shell  with  a  separate 
negative  pressure  generator.  The  shell  must  be  carefully  fit 
to  the  patient  based  on  measurements  of  the  width  of  the 
chest  and  the  distance  from  nipple  line  to  the  symphysis 
pubis.  Improper  fit  can  seriously  impair  the  effectiveness 
of  the  device.  The  chest  shell  is  the  least  efficient  of  the 
negative  pressure  ventilators,  but  offers  some  distinct  ad- 
vantages. It  is  relatively  easy  to  apply  to  the  patient  and 


also  allows  the  patient  to  sit  reasonably  upright.  Although 
not  as  effective  at  supplementing  W-y.  in  those  patients  who 
refuse  to  use  bi-level  pressure  ventilators  and  nasal  or  oro- 
nasal  masks,  the  chest  shell  may  offer  an  adequate  substitute. 
A  variation  of  the  chest  shell  is  the  body  wrap.  The 
patient  wears  a  poncho  or  jumpsuit-type  wrap  over  a  half 
moon-shaped  wire  cage.  The  wrap  is  then  connected  to  a 
negative  pressure  generator,  like  the  chest  shell.  The  wrap 
avoids  some  of  the  fit  problems  associated  with  the  shell. 


694 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Methods  to  Avoid  Intubation 


Fig.  8.  A  modified  nonrebreathing  masl<  for  delivering  helium  and 
oxygen  mixtures  (heliox).  A  ventilator  Y-piece  allow/s  inclusion  of  a 
standard  small  volume  nebulizer  in  order  to  provide  aerosol  ther- 
apy without  interrupting  the  heliox  delivery. 


Fig.  9.  A  80%  helium  to  20%  oxygen  mixture  (heliox)  cylinder  v\/ith 
a  "heliox  mask"  prepared  for  use.  The  2  standard  oxygen  flow 
meters  are  not  calibrated  for  heliox  delivery,  and  therefore  provide 
an  actual  flow  of  1 .8  times  the  displayed  flow. 


but  introduces  other  issues.  The  cage  must  be  sufficiently 
large  to  allow  adequate  chest  excursion.  The  wrap  must  be 
tightly  secured  at  the  neck,  arms,  and  legs  or  waist  to 
prevent  leaks  that  compromise  Vy. 

A  problem  associated  with  all  NPV  devices  is  the  po- 
tential for  precipitating  a  period  of  obstructive  apnea.-'''  -''^ 
This  is  likely  due  to  a  mechanical  inspiration  occurring 
prior  to  a  spontaneous  inspiratory  effort,  which  includes  a 
pre-inspiratory  stabilization  of  the  upper  airway.  A  trache- 
ostomy resolves  this  problem  but  fails  to  meet  the  goal  of 
avoiding  intubation.  Studies  have  also  demonstrated  that 
NPV  is  less  effective  than  NPPV  at  reducing  WOB  in 
patients  with  an  acute  exacerbation  of  COPD.'^-*'^'^  The 
application  of  NPV  is  not  well  suited  for  the  treatment  of 
ARF  because  of  the  complicated  and  lengthy  application 
time  required.  It  may  be  best  suited  to  patients  with  neu- 
romuscular disease  who  require  chronic  intermittent  ven- 
tilatory support,  or  as  an  option  for  patients  who  find 
bi-level  pressure  ventilation  via  mask  unacceptable. 

Rocking  Beds  and  Pneumobelts 

Rocking  beds,  first  used  in  the  early  1 940s  for  support 
of  ventilation,''^  and  pneumobelts,  which  were  introduced 
in  the  IQSO's,'^  are  rarely  used  today.  They  both  function 


by  displacing  the  abdominal  viscera  upwards  toward  the 
thorax  to  drive  air  out  of  the  lungs  and  then  allowing  the 
diaphragm  to  fall,  drawing  air  into  the  lungs.  Neither  de- 
vice is  useful  in  the  treatment  of  ARF  because  of  their 
particular  limitations,  but  there  may  be  specific  occasions 
where  they  can  support  ventilation  in  patients  with  chronic 
muscle  weakness,  and  thus  avoid  the  need  for  intubation. 

Rocking  beds  create  the  greatest  diaphragmatic  move- 
ment when  moving  from  neutral  (horizontal)  position  to 
the  approximate  40°  foot-down  position.'''*'''^  The  optimum 
rate  appears  to  be  between  1 2  and  1 6  breaths  per  minute, 
since  higher  frequencies  tend  to  reduce  the  Vt.""  Their 
effectiveness  is  related  to  body  shape:  subjects  with  longer 
abdomens  experience  increased  ventilation,  and  those  with 
lower  abdominal  compliance  experience  reduced  minute 
ventilation. 

Pneumobelts  use  a  bladder  that  inflates  periodically  to 
compress  the  abdominal  compartment  and  push  the  vis- 
cera upwards,  forcing  air  out  of  the  lungs.  When  the  blad- 
der deflates,  the  diaphragm  falls,  causing  inspiration.  The 
patient  must  be  in  a  sitting  position  during  its  use,  since  the 
inspiration  depends  on  gravity  pulling  the  diaphragm  down. 
Bladder  pressures  of  15-50  cm  HjO  are  used,  and,  like  the 
rocking  bed,  body  type,  lung/chest  wall  compliance,  and 
abdominal  compliance  all  greatly  influence  effectiveness. 


Respiratory  Care  •  June  1999  Vol  44  No  6 


695 


Methods  to  Avoid  Intubation 


While  the  rocking  bed  and  pneumobelt  may  not  be  the 
first  choice  for  supporting  patients  with  chronic  respira- 
tory insufficiency,  they  may  be  useful  as  an  alternative  to 
allow  some  patients  time  off  of  the  mask  or  other  forms  of 
noninvasive  ventilation. 

Diaphragmatic  Pacemaking 

Electrical  stimulation  of  the  phrenic  nerve  can  be  con- 
sidered noninvasive  ventilation,  since  it  utilizes  the  pa- 
tient's existing  ventilatory  muscles  and  may  not  require  an 
artificial  airway.  It  does  require  the  surgical  implantation 
of  electrodes  onto  one  or  both  of  the  phrenic  nerves.  These 
electrodes  are  connected  to  a  radio  receiver  that  is  also 
implanted  in  a  subcutaneous  pocket.  An  external  transmit- 
ter and  antenna  send  energy  pulses  to  the  receiver,  causing 
phrenic  nerve  stimulation.  When  the  signal  is  terminated, 
the  diaphragm  relaxes  and  exhalation  begins.  The  patient's 
breathing  pattern  is  controlled  by  adjusting  the  external 
transmitter  to  achieve  the  desired  rate,  W-y,  and  inspiratory 
to  expiratory  ratio. 

The  effectiveness  of  diaphragmatic  pacemaking  requires 
that  the  patient  have  a  functional  phrenic  nerve  and  dia- 
phragm. There  have  also  been  reports  of  nerve  injury  oc- 
curring during  the  implantation  procedure,  which  can  ren- 
der the  device  ineffective.  Additionally,  the  patient  should 
have  near-normal  lung  and  chest  wall  compliance.  The 
most  common  diagnoses  that  respond  well  to  diaphrag- 
matic pacing  are  high  spinal  cord  injuries  and  central  hy- 
poventilation syndrome. 

Over  1 ,500  patients  worldwide  have  had  phrenic  pacers 
implanted  since  1968.  The  potential  benefits  of  diaphrag- 
matic pacing  include  eliminating  the  need  for  a  mechani- 
cal ventilator  and  supplies,  eliminating  the  need  for  an 
artificial  airway,  the  ability  to  communicate  and  swallow 
more  normally,  and  increased  patient  mobility  allowed  by 
the  small  size  of  the  device. 

According  to  some  studies,*'-''-  a  tracheostomy  is  re- 
quired in  as  many  as  90%  of  patients  being  diaphragmat- 
ically  paced,  so  as  to  avoid  periods  of  obstructive  apnea 
and  to  allow  suctioning,  since  exhalation  remains  passive 
and  secretion  clearance  can  be  problematic  without  an 
effective  cough.  Another  issue  to  consider  when  contem- 
plating phrenic  pacing  is  cost.  The  necessary  equipment 
costs  as  much  as  $20,000,  but  one  study  estimated  that  the 
total  costs,  including  surgical  costs,  hospital  fees,  and  other 
costs  exceeded  $200,000  in  1991.''-''  Since  avoiding  an  ar- 
tificial airway  is  successfully  accomplished  in  some  pa- 
tients, diaphragmatic  pacing  can  be  considered,  but  non- 
invasive ventilation  may  continue  to  be  more  successful  at 
providing  ventilatory  assistance  to  these  patients  without 
the  need  for  intubation. 


Secretion  Clearance 

Inability  to  manage  adequate  pulmonary  hygiene  can 
for  some  patients  result  in  endotracheal  intubation.  An 
ineffective  cough  in  spontaneously  breathing  patients  can 
be  augmented  with  a  variety  of  alternative  cough-like  ma- 
neuvers, which  include  forced  exhalation  technique,  active 
cycle  breathing,  and  autogenic  drainage.  Postural  drain- 
age, percussion,  and  vibration  can  help  mobilize  secre- 
tions, but  is  labor  intensive  and  may  not  be  provided  at  the 
frequency  required.  Mechanical  versions  of  postural  drain- 
age, percussion,  and  vibration  have  been  introduced,  and 
include  positive  expiratory  pressure  valves,  flutter  valves, 
the  intrapulmonary  percussive  ventilator,  and  high- 
frequency  chest  wall  compression  vests,  with  each  method 
being  studied  found  to  have  some  potential  value. 

In  the  patient  with  poor  or  nonexistent  cough  because  of 
muscle  weakness,  mobilizing  secretions  is  not  the  same  as 
clearing  them.  Active  removal  can  only  be  accomplished 
by  nasotracheal  suction  or  artificial  coughing.  Since  naso- 
tracheal suctioning  is  painful,  invasive,  and  not  without 
risk,  it  is  not  preferred  as  an  option  for  long-term  man- 
agement of  secretions  in  the  nonintubated  patient.  Quad 
coughing  (manually  compressing  the  abdomen  and  forcing 
the  diaphragm  upwards  to  simulate  a  cough)  has  limited 
effectiveness,  since  it  is  difficult  to  achieve  a  deep  inspi- 
ration and  increased  airway  pressure  prior  to  the  abdom- 
inal compression.  The  resulting  "cough"  lacks  the  high 
expiratory  flow  that  is  the  hallmark  of  an  effective  cough. 

Currently  the  most  effective  method  to  produce  an  ar- 
tificial cough  in  the  patient  with  significant  muscle  weak- 
ness is  with  the  in-exsufflator  (JH  Emerson,  Cambridge, 
Massachusetts).*"*  This  device  forces  an  inspiration  to  close 
to  total  lung  capacity  and  then  abruptly  applies  negative 
pressure  to  the  airway.  In  20  patients  with  impaired  cough, 
Bach  compared  3  different  assisted  cough  methods  to  an 
unassisted  cough.  The  results  show  the  in-exsufflator 
achieved  significantly  higher  peak  expiratory  flow  rates 
than  breath  stacking  and  assisted  (quad)  coughing  (Fig. 
10).  Candidates  for  in-exsufflator  therapy  will  generally 
have  neuromusculature  disease  (eg,  amyotrophic  lateral 
sclerosis,  muscular  dystrophy,  myasthenia  gravis,  Guillain 
Barre,  spinal  cord  injury),  and  exhibit  significant  muscle 
weakness,  poor  cough,  and  secretion  clearance  problems. 
The  goal  is  to  mimic  a  normal  cough  by  applying  inspira- 
tory pressure  of  30-40  cm  HjO  and  then  creating  a  sud- 
den, rapid  exhalation  by  reversing  the  pressure  to  a  neg- 
ative 35-45  cm  HjO.  Settings  must  be  individually  adju.sted 
for  each  patient,  and  success  is  based  of  the  ability  to  clear 
secretions.  When  initially  orienting  a  patient  to  this  ther- 
apy, lower  pressures  and  slower  flow  rates  may  be  useful 
while  the  patient  acclimates  to  the  device.  Pressures  and 
flows  can  be  slowly  increased  as  tolerated  until  optimal 
settings  are  achieved. 


696 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Methods  to  Avoid  Intubation 


Unassisted      Stacking        Assisted 


In- 

Exsufflator 


Fig.  10.  Comparison  of  effectiveness  between  3  different  artificial 
cougtiing  tectnniques  in  the  unassisted  patient  witti  neuromuscular 
disease.  PEFR  =  peak  expiratory  flow  rate.  (Adapted  from  data  in 
Reference  64.) 

Specific  contraindications  of  in-exsufflator-assisted 
cough  include  recent  barotrauma  or  risk  of  barotrauma  (eg, 
bullous  emphysema).  Patients  with  small  airway  disease 
(eg,  COPD)  are  not  specifically  excluded  from  this  ther- 
apy, but  in  these  patients  use  of  the  in-exsuftlator  should 
be  considered  cautiously.  Aggressive  negative  expiratory 
pressure  may  promote  small  airway  collapse  and  increase 
air  trapping.  Additionally,  patients  with  reasonably  intact 
neuromuscular  status  may  resist  the  action  of  the  device 
and  limit  its  effectiveness. 

Summary 

Noninvasive  strategies  to  avoid  intubation  are  varied, 
each  addressing  a  different  need  of  the  acute  and  chroni- 
cally ill.  The  benefits  include  lower  mortality  rates,  shorter 
lengths  of  hospitalization,  improved  quality  of  life,  re- 
duced costs,  and  the  avoidance  of  the  risks  and  discomfort 
associated  with  artificial  airways.  Although  this  article  cited 
numerous  examples  of  successful  avoidance  of  intubation, 
these  methods  do  not  work  for  all  patients.  Nocturnal  nasal 
ventilation,  while  not  routinely  accepted  by  all  COPD  pa- 
tients, has  provided  relief  and  improved  the  quality  of  life 
for  many.  NPPV  as  a  therapy  for  managing  ARF  has  averted 
intubation  in  a  significant  number  of  patients  who  previ- 
ously would  have  received  invasive  mechanical  ventila- 
tion, particularly  patients  suffering  acute  exacerbation  of 
COPD. 

CPAP  for  the  treatment  of  cardiogenic  pulmonary  edema 
may  have  some  benefit  over  the  use  of  NPPV,  but  further 
research  is  needed  to  better  answer  this  question.  Noctur- 
nal CPAP  has  become  the  standard  of  care  for  OSA.  He- 
liox  is  an  excellent  adjunct  in  the  treatment  of  asthma  and 
upper  airway  obstruction.  Negative  pressure  ventilation 
has  declined  in  use,  but  there  may  be  patients  who  derive 
great  benefit  from  it  if  we  retain  it  as  an  option.  Including 
a  pneumobelt  as  a  daytime  option  for  the  patient  with 
neuromusculature  disease  could  offer  new  flexibility  to 
their  life.  Diaphragmatic  pacing  appears  costly  yet  offers 


patients  with  intact  phrenic  nerves  and  diaphragms  an  al- 
ternative to  other  mechanical  devices  that  may  limit  their 
mobility.  In-exsufflators  are  difficult  to  acclimate  to,  but, 
for  some  patients  with  neuromuscular  disease,  may  be 
instrumental  in  the  prevention  of  chronic  infection  that 
would  require  tracheostomy  for  pulmonary  hygiene.  The 
growing  need  for  noninvasive  approaches  continues  to  spur 
our  interest  in  both  new  and  old  options.  Each  must  be 
considered  carefully,  and  our  techniques  evaluated  with 
the  goal  of  improving  our  success  rate  at  avoiding  intuba- 
tion and  improving  care. 

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pressure  ventilation  in  patients  with  acute  respiratory  failure:  diffi- 
cult and  time  consuming  procedure  for  nurses.  Chest  1991:100(3): 
775-782. 

68.  Hodson  ME,  Madden  BP.  Steven  MH,  Tsang  VT.  Yacoub  MH. 
Non-invasive  mechanical  ventilation  for  cystic  fibrosis  patients:  a 
potential  bridge  to  tran.splantation.  Eur  Respir  J  1991 :4{5):524-527. 

69.  Marino  W.  Intermittent  volume  cycled  mechanical  ventilation  via 
nasal  mask  in  patients  with  respiratory  failure  due  to  COPD.  Chest 
1 991 ,99(3  ):68 1-684. 

Meduri  GU,  Abou-Shala  N,  Fox  RC,  Jones  CB,  Leeper  KV,  Wun- 
derink  RG.  Noninvasive  face  mask  ventilation  in  patients  with  acute 
hypercapnic  respiratory  failure.  Chest  1991;l()()(2):445-454. 
Pennock  BE,  Kaplan  PD.  Carlin  BW,  Sabangan  JS,  Magovern  JA. 
Pressure  support  ventilation  with  a  simplified  ventilatory  support 
system  administered  with  a  nasal  mask  in  patients  with  respiratory 
failure.  Chest  199I:I00(5):I371-1376. 

72.  Benhamou  D.  Giraull  C.  Faure  C.  Portier  F.  Muir  JF.  Nasal  mask 
ventilation  in  acule  respiratory  failure:  experience  in  elderly  patients. 
Chest  1992:102(3):912-917. 

73.  Foglio  C.  Vitacca  M.  Quadri  A,  Scalvini  S,  Marangoni  S.  Ambrosino 
N.  Acute  exacerbations  in  severe  COLD  patients:  treatments  using 
positive  pressure  ventilation  by  nasal  mask.  Chest  1992:101(6):  1533- 
1538. 

74.  Udwadia  ZF.  Santis  GK,  Steven  MH.  Simonds  AK.  Nasal  ventilation 
to  facilitate  weaning  in  patients  with  chronic  respiratory  insuffi- 
ciency. Thorax  I992;47(9):715-718. 

75.  Bott  J.  Carroll  MP.  Conway  JH.  Keilty  SE,  Ward  EM.  Brown  AM. 
et  al.  Randomized  controlled  trial  of  nasal  ventilation  in  acute  ven- 
tilatory failure  due  to  chronic  obstructive  airways  di.sease.  Lancet 
1993:.341(8860):155.5-I557. 

76.  Conway  JH,  Hitchcock  RA.  Godfrey  RC.  Carroll  MP.  Nasal  inter- 
mittent positive  pressure  ventilation  in  acute  exacerbations  of  chronic 


70, 


71 


80 


^1. 


82 


83 


obstructive  pulmonary  disease:  a  preliminary  study.  Respir  Med  1 993; 
87(5):387-394. 

77.  Fernandez  R.  Blanch  L,  Valles  J,  Baigorri  F,  Artigas  A.  Pressure 
support  ventilation  via  face  mask  in  acute  respiratory  failure  in  hy- 
percapnic COPD  patients.  Intensive  Care  Med  1993;19(8):456-461. 

78.  Restrick  LJ.  Scott  AD,  Ward  EM,  Feneck  RO,  Cornwell  WE, 
Wedzicha  JA.  Nasal  intermittent  positive-pressure  ventilation  in 
weaning  intubated  patients  with  chronic  respiratory  disease  from 
assisted  intermittent  positive-pressure  ventilation.  Respir  Med  1993; 
87(3):  199-204. 

79.  Wysocki  M,  Trie  L.  Wolff  MA,  Gertner  J,  Millet  H,  Herman  B. 
Noninvasive  pressure  support  ventilation  in  patients  with  acute  re- 
spiratory failure.  Chest  I993;103(3):907-9I3. 
Lapinsky  SE,  Mount  DB.  Mackey  D,  Grossman  RF.  Management  of 
acute  respiratory  failure  due  to  pulmonary  edema  with  nasal  positive 
pressure  support.  Chest  1994;105(  1):229-231. 
Meduri  GU.  Fox  RC,  Abou-Shala,  Leeper  KV.  Wunderink  RG.  Non- 
invasive mechanical  ventilation  via  face  mask  in  patients  with  acute 
respiratory  failure  who  refused  endotracheal  intubation.  Crit  Care 
Med  1994:22(10):  1584- 1590. 

Pennock  BE,  Craw.shaw  L,  Kaplan  PD.  Noninvasive  nasal  mask 
ventilation  for  acute  respiratory  failure:  institution  of  a  new  thera- 
peutic technology  for  routine  u.se.  Chest  1994:I05(2):441^44. 
Soo  Hoo  GW.  Santiago  S.  Williams  AJ.  Nasal  mechanical  ventila- 
tion for  hypercapnic  respiratory  failure  in  chronic  obstructive  pul- 
monary disease:  determinates  of  success  and  failure.  Crit  Care  Med 
I994;22(8):1253-1261. 

84.  Tognet  E,  Mercatello  A.  Polo  P.  Coronel  B,  Bret  M,  Archimbaud  E. 
Moskovtchenk  JF.  Treatment  of  acute  respiratory  failure  with  non- 
invasive intermittent  positive  pres.sure  ventilation  in  haematological 
patients.  Clin  Itensive  Care  1994;5(6):282-288. 

85.  Ambrosino  N,  Foglio  K.  Rubini  F.  Clini  C.  Nava  S.  Vitacca  M. 
Non-invasive  mechanical  ventilation  in  acute  respiratory  failure  due 
to  chronic  obstructive  pulmonary  di.sease:  correlates  for  success. 
Thorax  1995;50(7):755-757. 

86.  Chaing  AA,  Lee  KC.  Use  of  noninvasive  positive  pressure  ventila- 
tion via  nasal  mask  in  patients  with  respiratory  distress  after  extu- 
bation.  Chung  Hual  Hsueh  Tsa  Chih  (Taipei)  1995;56(2):94-101. 

87.  Pollack  CV  Jr,  Fleisch  KB,  Dowsey  K.  Treatment  of  acute  broncho- 
spasm  with  B-adrenergic  agonist  aerosols  delivered  by  a  nasal  bi- 
level  positive  airway  pressure  circuit.  Ann  Emerg  Med  1995:26(5): 
552-557. 

88.  Sacchetti  AD,  Harris  RH,  Paslon  C.  Hernandez  Z.  Bi-level  positive 
airway  pressure  support  system  use  in  acute  congestive  heart  failure: 
preliminary  case  series  (review).  Acad  Emerg  Med  1995;2{8):714-7I8. 
Meduri  GU.  Cook  TR.  Turner  RE,  Cohen  M.  Leeper  KV.  Noninva- 
sive positive  pressure  ventilation  in  status  a.sthmaticus.  Chest  1996; 
1 1()(3):767-774. 

Patrick  W,  Webster  K,  Ludwig  L,  Roberts  D,  Wiebe  P,  Younes  M. 
Noninvasive  positive-pressure  ventilation  in  acute  respiratory  dis- 
tress without  prior  chronic  respiratory  failure.  Am  J  Respir  Crit  Care 
Med  1996;153(3):1005-10ll. 


89. 


90, 


Discussion 

Branson:  I  was  glad  that  you  made 
the  clear  distinction  (which  Dean  Hess 
is  probably  tired  of  hearing  me  talk 
about  by  now)  that  BiPAP  is  a  device, 
not  a  technique,  and  that  what  we  do 
with  the  BiPAP  device  is  provide  pres- 
sure support.  I  know  my  emergency 


medicine  colleagues  think  BiPAP  is 
something  different  than  all  the  other 
ventilators  in  the  world,  and  that  they 
can't  use  a  Nellcor  Puritan  Bennett 
7200  to  do  noninvasive  ventilation. 
That's  just  a  comment.  My  other  feel- 
ing is  that  with  all  the  history  we  have 
of  doing  mask  CPAP  and  looking  at 
success  against  how  many  patients 


didn't  get  intubated,  I  always  felt  there 
the  same  thing  I  felt  about  noninva- 
sive ventilation,  and  that  is,  if  you're 
not  too  sick,  this  stuff  works.  If  you're 
really  sick,  it's  not  going  to  work.  I 
really  think  the  mortality  rate,  stuff 
we  see  in  the  literature  and  that  you 
reported,  has  a  lot  to  do  with  that.  If 
noninvasive  ventilation  works,  then 


Respiratory  Care  •  June  1999  Vol  44  No  6 


699 


Methods  to  Avoid  Intubation 


you're  probably  not  that  sick,  so  the 
observed  mortahty  rate  isn't  that  great. 
If  noninvasive  doesn't  work,  you're 
probably  much  sicker  and  your  mor- 
tality rate  is  greater.  I  don't  know  that 
the  technique  in  itself  results  in  a  lower 
mortality.  I  would  be  happy  to  hear 
any  suggestions. 

Ritz:  I  think  that's  absolutely  right. 
And  the  problem  you  keep  running 
into  is  that  real  sick  patients  stay  real 
sick.  But,  I  think  there's  probably  a 
benefit.  If  you  look  at  the  rate  of  nos- 
ocomial pneumonia,  we  would  have 
to  assume  that  if  we  all  agree  that  in- 
tubation is  undesirable  and  that  we 
want  to  avoid  it,  then  maybe  the  mor- 
tality rates  and  length  of  stay  rates 
'don't  really  tell  us  what  we'd  like  to 
know.  But  they  may  very  well  point 
to  the  fact  that  this  is  probably  a  ben- 
eficial thing  to  do  to  patients.  Clearly, 
we  see  a  number  of  probably  unnec- 
essary intubations,  but  I  agree  with 
your  comment. 

Hess:  I  think  your  point  would  be 
correct  if  all  we  had  were  case  series 
for  noninvasive  ventilation.  But,  now 
several  prospective  randomized  con- 
trol trials  of  noninvasive  ventilation 
have  shown  a  survival  benefit  to  non- 
invasive ventilation.' " 


REFERENCES 

1,  Brochard  L,  Mancebo  J,  Wysocki  M,  Lo- 
faso  F,  Conti  G,  Rauss  A,  et  al.  Noninva- 
sive ventilation  for  acute  exacerbations  of 
chronic  obstructive  pulmonary  disease. 
N  Engl  J  Med  1995;333(l3):817-822. 

2.  Nava  S,  Ambrosino  N,  Clini  E,  Prato  M, 
Orlando  G,  Vitacca  M,  et  al.  Noninvasive 
mechanical  ventilation  in  the  weaning  of 
patients  with  respiratory  failure  due  to 
chronic  obstructive  pulmonary  disease:  a 
randomized,  controlled  trial.  Ann  Intern 
Med  1998;128(9):72l-728. 


*David  J  Pierson  MD,  Division  of  Pulmonary 
&  Critical  Care  Medicine,  Department  of  Med- 
icine, University  of  Washington,  Seattle,  Wash- 
ington. 


Branson:  I  have  talked  to  some  of 
people,  including  Nick  Hill's  group, 
who  indicate  that  when  a  patient  fails 
noninvasive  ventilation,  quite  often 
that  patient  is  placed  in  the  conven- 
tional ventilation  group.  Researchers 
tend  to  say  "I  have  all  these  patients 
on  noninvasive  ventilation,  and  20% 
of  them  get  intubated.  When  I  do  my 
data  analysis,  I'll  put  them  in  the  me- 
chanical ventilation  group."  Well,  that, 
in  and  of  itself,  biases  that  group  to  be 
the  sicker  group.  I'm  not  disputing  that 
we  should  do  noninvasive  ventilation. 
Obviously  we  should.  I'm  just  saying 
that  it's  my  impression  from  looking 
at  it  that  the  sicker  patients  go  on  the 
ventilator,  and  that's  why  they  have  a 
higher  mortality.  The  presence  of  the 
tube  and  nosocomial  pneumonia  may 
contribute  to  that. 

StoUer:  I  would  disagree  with  that 
comment.  Certainly  in  Nick  Hill's 
group's  paper,'  the  analysis  was  done 
in  an  intention-to-treat  mode.  That  is 
to  say,  patients,  once  allocated  to  the 
treatment  groups,  are  analyzed  in  that 
treatment  group  regardless  of  whether 
they  cross  over  to  the  intubated  group. 
In  this  way,  the  analysis  sticks  to  the 
initial  allocation  arm.  So  that  would 
tend  to  negate  the  potential  argument 
that  you,  appropriately,  advance,  ex- 
cept that  it's  not  borne  out  by  the  ac- 
tual analysis  in  those  series.  The  mor- 
tality disadvantage  is  not  due  to  the 
impact  of  crossing  over.  I  think  sev- 
eral other  papers  have  used  an  inten- 
tion-to-treat analysis,  which  is,  of 
course,  an  important  analytic  princi- 
ple in  a  randomized  trial,  otherwise  it 
would  obviate  the  advantage  of  ran- 
domized allocation.  The  other  point, 
and  I  think  Dean  said  it  in  his  paper 
before,  was  about  Nava's  paper,^ 
which  looked  at  a  randomized  trial  of 
a  strategy  of  extubating  patients  with 
COPD  to  look  at  noninvasive  strate- 
gies as  a  facilitator  of  rapid  extuba- 
tion.  It  was  in  that  series,  after  initial 
intubation,  that  the  rate  of  nosocomial 
pneumonia  was  found  to  be  lower  in 
the  noninvasively  managed  group.  So, 


there  does  seem  to  be  a  "nosocomial 
pneumonia  advantage"  of  noninvasive 
techniques.  I  think  you.  Dean,  alluded 
to  that  in  your  talk  earlier  today. 


REFERENCES 

1 .  Kramer  N,  Meyer  TJ,  Meharg  J,  Cece  RD, 
Hill  NS.  Randomized,  prospective  trial  of 
noninvasive  positive  pressure  ventilation 
in  acute  respiratory  failure.  Am  J  Respir 
Crit  Care  Med  1995;151(6):1799-I806. 

2.  Nava  S,  Ambrosino  N,  Clini  E,  Prato  M, 
Orlando  G,  Vitacca  M,  et  al.  Noninvasive 
mechanical  ventilation  in  the  weaning  of 
patients  with  respiratory  failure  due  to 
chronic  obstructive  pulmonary  disease:  a 
randomized,  controlled  trial.  Ann  Intern 
Med  1998;l28(9):721-728. 


Branson:  I  agree.  We  all  agree  that 
it's  not  ventilator-associated  pneumo- 
nia, it's  really  endotracheal-tube- 
associated  pneumonia.  And,  I  see  that 
as  the  advantage.  I'm  still  troubled. 
Again,  all  this  stuff  happened  with 
mask  CPAP.  Putensen's  group  did  a 
study  where  they  extubated  people 
with  hypoxemic  respiratory  failure, 
and  took  them  right  to  mask  CPAP 
for  the  same  advantages,  and  had  sim- 
ilar kinds  of  outcomes. '  I'm  still  strug- 
gling with  the  fact  that  it  appears  that 
noninvasive  ventilation  decreases 
mortality?  Is  that  solely  because  of 
nosocomial  pneumonia,  or  is  it  some- 
thing else?  I'd  just  be  interested  to  know 
the  explanation  behind  the  finding.  We 
have  the  finding,  but  no  explanation  for 
it;  we  have  just  accepted  it. 

REFERENCE 

I .  Putensen  C,  Hermann  C,  Baum  M,  Ling- 
nau  W.  Comparison  of  mask  and  nasal 
continuous  positive  airway  pressure  after 
extubation  and  mechanical  ventilation.  Crit 
Care  Med  1993;21(3):357-362. 

Hess:  I  don't  know  that  anybody 
knows  exactly  what  it  is.  I  don't  know 
that  anyone  has  tried  to  investigate  the 
causal  relationship. 

Pierson:*  In  the  absence  of  data,  I 
would  be  happy  to  advance  a  hypoth- 


700 


Respiratory  Care  •  June  1999  Vol  44  No  6 


Methods  to  Avoid  Intubation 


esis,  and  that  is  that  when  we  have 
people  invasively  ventilated,  we  are 
biasing  the  process  toward  their  stay- 
ing on  the  ventilator  if  we  are  not  per- 
fect in  knowing  exactly  when  they 
have  recovered.  Whereas,  if  we  have 
people  noninvasively  ventilated,  we 
are  biasing  the  process  toward  less  in- 
vasion, even  if  we're  not  assessing 
them  as  often  as  we  should  be.  Does 
that  make  sense?  The  fact  that  some 
patients  extubate  themselves  is  evi- 


dence that  we  sometimes  don't  assess 
people  often  enough  for  their  rate  of 
recovery,  and,  therefore,  if  they  re- 
main intubated,  we're  biasing  the 
whole  system  toward  prolonging  a 
therapy  that's  no  longer  necessary.  In 
that  situation,  you're  predisposing  to- 
ward iatrogenic  problems. 

Ritz:  It's  interesting,  Dave,  that  you 
bring  that  point  up.  When  we  were 
implementing  our  noninvasive  venti- 


lation program  at  Massachusetts  Gen- 
eral Hospital,  Dean  came  up  with  a 
very  algorithmic  approach  to  weaning 
noninvasive  ventilation,  and  we  never 
used  it  because  what  happened  was 
the  patient  took  the  mask  off.  We  get 
kind  of  excited  when  patients  take  their 
endotracheal  tubes  out,  but  we  gener- 
ally saw  it  as  a  good  sign  when  they 
took  their  noninvasive  mask  off,  at 
least  after  their  fatigue  seemed  to 
dissipate. 


Respiratory  Care  •  June  1999  Vol  44  No  6 


701 


Listing  and  Reviews  of  Bool<s  and  Otiier  Media.  Note  to  publishers:  Send  review  copies  of  boolis, 
films,  tapes,  and  software  to  Respiratory  CarI:.  600  Ninth  Avenue,  Suite  702,  Seattle  WA  98104. 


Books,  Films, 
Tapes,  &  Software 


SymBioSys  PFT  Pulmonary  Function 
Test.  Chicago  IL:  Critical  Concepts.  1997. 
$99.00. 

System  Requirements:  PC  with  Win- 
dows 3. 1  or  Windows  95,  minimum  486/66 
processor.  16  MB  RAM.  12  MB  hard  disk 
(full  in.stallation),  CD-ROM  (for  installa- 
tion only). 

The  SymBjoSys  PFT  Pulmonary 
Function  Test  software  package  is  an  in- 
teractive educational  program  designed  for 
a  wide  range  of  users,  including  medical 
students,  pulmonary  fellows,  respiratory 
therapists,  pulmonary  function  technolo- 
gists, nurses,  and  nurse  practitioners.  It 
presents  core  "lectures"  on  pulmonary  phys- 
iology and  pulmonary  function  interpreta- 
tion complemented  with  real  time  simula- 
tions in  a  hypertext  format. 

The  program  is  easy  to  install  and  begin 
using.  From  the  initial  screen,  the  learner  is 
easily  directed  to  the  core  curriculum  by 
instructions  to  press  the  "Exercise  Help" 
link.  The  lessons  are  well  organized  into 
conceptual  groups  or  chapters.  Chapter  1  is 
simply  a  guide  to  the  SimS/oSys  interface. 
Chapter  2  introduces  users  to  principles  of 
static  pulmonary  physiology:  lung  volumes, 
deterininants  of  static  lung  properties,  and 
chest  wall  mechanics.  The  final  lesson  in 
this  section,  integrated  respiratory  statics, 
illustrates  how  the  static  properties  of  the 
entire  respiratory  system  determine  com- 
mon measurements  of  pulmonary  function, 
such  as  total  lung  capacity,  functional  re- 
sidual capacity,  and  residual  volume.  Chap- 
ter ?>  covers  respiratory  system  dynamics 
with  lessons  on  forced  expiration,  errors  in 
forced  expiratory  measurements,  the  flow 
volume  loop,  and  airways  resistance.  In  this 
section,  the  simulated  spirometry  tracings 
are  particularly  effective  in  demonstrating 
the  effects  of  changes  in  airways  resistance 
and  elastic  recoil.  Chapter  4  discusses  gas 
exchange  measurements  such  as  the  mea- 
surement of  the  diffusing  capacity  for  car- 
bon monoxide  and  blood  gas  analysis. 
Chapter  5  gives  a  brief  introduction  to  the 
measurement  of  inspiratory  and  expiratory 
force  for  assessing  respiratory  muscle 
strength.  Chapter  6  integrates  the  principles 
covered  in  the  previous  chapters  by  dem- 
onstrating how  static  and  dynamic  PFTs 


are  affected  in  4  common  diseases:  restric- 
tive lung  disease,  emphysema,  bronchitis, 
and  asthma.  In  the  final  chapter,  6  cases  are 
presented  with  findings  on  physical  exam 
and  chest  x-rays  in  addition  to  spirometry, 
lung  volumes,  and  diffusing  capacity. 

The  core  text  presented  in  the  lessons 
begins  at  a  basic  level  but  quickly  progresses 
to  a  inoderately  sophisticated  level  that  may 
be  beyond  the  level  of  certain  users,  such 
as  medical  students,  who  have  no  prior 
background.  Respiratory  physiology,  a 
particularly  complex  topic,  may  be  diffi- 
cult for  some  users  to  understand  without 
additional  educational  resources.  The  Sim- 
BioSys  PFT  prograin  does  address  this  is- 
sue to  some  extent  by  including  additional 
topics  and  more  in-depth  discussions  under 
the  "Physiology  Help"  menu. 

A  particular  strength  of  the  SymBwSys 
cuniculum  is  its  approach  to  PFT  from  a 
variety  of  perspectives.  Because  potential 
users  of  the  program  inay  be  pulinonary 
function  technicians  or  health  care  provid- 
ers, the  lessons  cover  the  physiologic  basis 
of  PFT  in  normal  and  disease  states  as  well 
as  the  procedures  involved  in  performing 
the  tests  themselves.  To  their  credit,  the 
program  authors  also  describe  situations  in 
which  technical  problems  can  give  rise  to 
spurious  data.  This  information  is  particu- 
larly important  for  both  pulmonary  techni- 
cians and  health  care  providers  interpreting 
the  tests,  but  the  latter  unfortunately  un- 
derappreciate it. 

The  side-by-side  text  and  simulation  win- 
dows within  the  lessons  provide  an  effec- 
tive educational  medium.  The  simulations 
are  of  high  quality,  and  the  illustrated  ef- 
fects of  changes  in  physiologic  parameters 
on  the  graphs  and  pulmonary  function  mea- 
surement is  extremely  helpful.  The  simu- 
lated pulmonary  function  tracings  for  the 
clinical  cases  are  excellent  and  even  enable 
the  learner  to  determine  whether  a  bron- 
chodilator  response  is  present.  However,  a 
possible  source  of  confusion  that  should  be 
addressed  in  subsequent  editions  is  the  fact 
that  the  simulated  tracings  for  each  case  are 
not  cleared  from  the  screen  when  the  next 
case  is  loaded. 

The  case  presentations  overall  are  a  help- 
ful adjunct  to  the  basic  lessons  but  could  be 
improved  by  some  refinement.  The  physi- 


cal findings  are  stated  in  a  manner  that  is  of 
limited  value  to  the  case.  Unfortunately,  the 
simulations  do  not  include  simulated  heart 
sounds  and  breath  sounds.  Similarly,  the  chest 
radiographic  findings  are  also  stated  rather 
than  visually  illustrated  and  therefore  are  not 
particularly  contributory  to  the  case  presen- 
tation. 

SymBioSys  PFT  has  taken  on  the  chal- 
lenge of  teaching  new  learners  pulmonary 
function  at  a  fairly  sophisticated  level.  Con- 
sidering the  fact  that  the  software  program  is 
relatively  new.  its  organization  is  excellent. 
The  simulated  PFTs  are  a  valuable  approach 
to  illustrating  concepts.  Although  the  pro- 
gram could  be  further  improved  and  refined, 
it  is  an  effective,  worthwhile  tool  for  teach- 
ing PFT. 

Jacqueline  Chang  MD 

Senior  Fellow 

Division  of  Pulmonary  and 

Critical  Care  Medicine 

Department  of  Medicine 

University  of  Washington 

Seattle,  Washington 

Respiratory  Care  Pharmacology,  5'''  ed. 

Joseph  L  Rau  Jr  PhD  RRT.  Soft-cover,  illus- 
trated, 408  pages.  St  Louis  MO:  Mosby-Year 
Book  Inc;  1998.  $.39.00. 

Respiratory  Care  Pharmacology,  .i''' 
edition,  contains  22  chapters  and  .'i  appen- 
dixes divided  into  3  units:  "Basic  Concepts 
and  Principles  in  Pharmacology,"  "Drugs 
Used  to  Treat  the  Respiratory  System,"  and 
"Critical  Care  and  Cardiovascular  Drug 
Classes."  Unit  one  contains  chapters  review- 
ing basic  pharinacology.  principles  of  drug 
action,  administration  of  aerosolized  agents, 
calculating  drug  doses,  and  an  introduction 
to  the  peripheral  and  central  nervous  system. 
Unit  Two  contains  chapters  detailing  the  phar- 
macology of  various  classes  of  agents  com- 
monly used  in  treating  diseases  of  the  respi- 
ratory system.  Unit  Three  contains  chapters 
providing  very  limited  overviews  of  other 
medication  classes  cominonly  used  in  the 
treatment  of  critically  ill  patients.  The  .S  ap- 
pendixes review  the  answers  to  the  self-as- 
sessinent  recommendations  on  the  use  of 
aerosol  generators,  pharmacologic  manage- 
ment of  asthma  and  chronic  obstructive  pul- 


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Respiratory  Care  •  June  99  Vol  44  No  6 


Books,  Films,  Tapes,  &  Software 


monary  disease,  and  drug-induced  pulmo- 
nary diseases. 

The  material  is  well  organized  with  each 
chapter  dedicated  to  a  specific  class  of 
agents.  Each  chapter  is  divided  into  an  in- 
troduction, history,  and  development  of  the 
medication  class;  a  discussion  of  the  dis- 
ease state  or  physical  condition  that  is  being 
treated;  the  clinical  applications;  and  a  re- 
view of  individual  agents.  The  discussion 
of  each  medication  includes  a  review  of  the 
mechanism  of  action,  indications  for  use, 
dose  and  administration,  and  side  effects. 
Each  chapter  concludes  with  a  chapter  sum- 
mary of  key  terms,  self-assessment  ques- 
tions, clinical  case  examples,  and  questions. 

The  intended  readership  of  this  book  is 
respiratory  care  students.  Each  chapter  is 
easy  to  read  and  written  in  a  language  geared 
to  the  entry-level  student.  The  book  may 
also  serve  as  a  quick  reference  for  the  ex- 
perienced respiratory  therapist,  but  the  chap- 
ters are  much  too  superficial  if  one  is  look- 
ing for  an  in-depth  review  on  a  particular 
agent  or  class  of  agents. 

The  strength  of  the  book  is  the  author's 
knowledge  of  the  pharmacology  of  respira- 
tory therapy  medications.  The  information 
used  to  support  the  discussions  is  well  ref- 
erenced and  the  author  indicates  when  is- 
sues are  speculative.  Most  facts  are  sup- 
ported with  up-to-date  references.  The 
author  reaches  appropriate  conclusions  re- 
garding the  topics  being  discussed.  He  goes 
to  great  lengths  to  define  complex  terms 
and  theories.  Many  discussions  include  clin- 
ical pearls  indicating  the  author's  signifi- 
cant clinical  experience.  For  the  reader  look- 
ing for  in-depth  information  on  a  particular 
subject,  the  author  frequently  refers  to  cur- 
rent review  articles. 

The  limitations  of  the  book  are  found  in 
the  chapters  dealing  with  nonrespiratory  care 
medications.  These  chapters  are  limited  by 
outdated  and  misinformation.  The  author 
frequently  uses  drugs  that  are  outdated  or 
no  longer  marketed  as  examples  throughout 
the  book  (ie,  glutethimide,  oxytetracycline, 
meprobamate,  paraldehyde,  isoetharine, 
Dalmane,  D-tubocurarine,  promazine, 
hyaluronidase,  demecarium,  ambenonium, 
kanamycin,  lincomycin,  polymyxin  B.  sul- 
fanilamide, hexafluorenium,  chlorothiazide, 
deserpidine,  rescinnamine,  alseroxylon, 
mecamylamine).  It  appears  that  these  ex- 
amples may  have  been  used  in  previous  edi- 
tions of  the  book  but  have  not  been  updated 
for  the  current  edition. 


In  Chapter  1 ,  the  author  incorrectly  states 
that  the  National  Formulary  is  published  by 
the  American  Society  of  Hospital  Pharma- 
cists. The  United  States  Pharmacopeial  Con- 
vention publishes  the  National  Formulary 
as  part  of  the  U.S.  Pharmacopeia.  The  Amer- 
ican Society  of  Hospital  Pharmacists  is  of- 
ficially known  as  the  American  Society  of 
Health-Systems  Pharmacists.  In  Chapter  2, 
the  author  defines  a  term  called  "the  phar- 
maceutical phase,"  but  it  is  unclear  where 
this  term  originated.  He  also  here  incorrectly 
defines  the  terms,  "clearance"  and  "half- 
life."  Many  of  the  statements  made  by  the 
author  are  incorrect,  such  as  the  statements 
in  Chapter  2,  "when  a  drug  is  highly  sus- 
ceptible to  the  first  pass  effect,  the  oral  route 
should  be  avoided  and  other  routes  of  ad- 
ministration considered"  and  "dosing  which 
occurs  more  frequently  than  the  half-life 
time  can  result  in  drug  accumulation  with 
side  effects  and  toxicity."  These  are  clearly 
incorrect  statements,  because  many  drugs 
that  undergo  first  pass  metabolism  are  mar- 
keted as  oral  dosage  forms  (ie,  morphine, 
verapamil,  labetalol),  and  drugs  with  long 
half-lives  are  frequently  administered  at  dos- 
ing intervals  less  than  their  resjjective  half- 
lives  (ie,  amiodarone  t|^2'  50  d,  digoxin  t|/2: 
3-5  d,  phenobarbital  t,/,:  3-5  d).  Also,  the 
half-life  of  phenobarbital  is  incorrectly  listed 
as  4. 1  hours.  Its  actual  half-life  is  3-5  days. 

Numerous  other  inaccuracies  appear 
throughout  the  book.  The  author  incorrectly 
states  that  hypersensitivity  reactions  to  pen- 
icillins are  more  likely  to  occur  with  paren- 
teral than  oral  route  of  administration,  first 
generation  cephalosporins  and  aminoglyco- 
sides have  no  activity  against  H.  influenzae, 
cephalosporins  can  result  in  acute  tubular 
necrosis,  and  sulfonamides  are  not  classi- 
fied as  antibiotics.  In  the  discussion  of  am- 
photericin B,  the  author  incorrectly  states 
that  hypotension  limits  its  use  and  that  flucy- 
tosine is  usually  used  in  combination  with 
amphotericin  B. 

In  the  "Cold  and  Cough  Agents"  chap- 
ter, the  author  incorrectly  states  that  keto- 
conazole  and  macrolide  antibiotics  increase 
the  concentration  of  loratadine,  resulting  in 
cardiotoxic  effects.  Although  these  agents 
do  inhibit  loratadine  metabolism,  resulting 
in  increased  serum  concentrations,  the  con- 
centrations are  not  associated  with  the  car- 
diac toxicity  that  is  seen  with  astemizole 
and  terfenadine. 

One  major  concern  is  in  the  section  on 
calculating  pediatric  doses  in  Chapter  17. 
The  author  describes  the  use  of  Fried's  rule. 


Young's  rule,  and  Clark's  rule  for  calculat- 
ing pediatric  doses  from  adult  doses.  These 
are  antiquated  recommendations  that  have 
never  been  proven  to  provide  the  correct 
doses.  The  use  of  these  "rules"  may  result 
in  doses  that  produce  therapeutic  failure  or 
toxicity  because  they  do  not  take  into  ac- 
count the  effects  of  age  on  the  pharmaco- 
kinetic and  pharmacodynamic  properties  of 
drugs.  The  use  of  these  rules  must  be 
avoided. 

In  Section  Three,  "Critical  Care  and  Car- 
diovascular Drug  Classes,"  the  author's  un- 
familiarity  with  these  classes  of  agents  again 
results  in  misleading  information.  Although 
the  author  classifies  mivacurium  as  an  in- 
termediate-acting neuromuscular  blocking 
agent,  it  is  more  accurately  classified  as  a 
short-acting  agent.  The  author  states  that  ci- 
satracurium  has  the  same  potential  for  caus- 
ing histamine  release  as  mivacurium  and 
atracurium.  In  fact,  cisatracurium  is  associ- 
ated with  minimal  potential  to  cause  hista- 
mine release.  The  author  also  states  that  neu- 
romuscular blocking  agents  can  be 
beneficial  in  the  treatment  of  status  asth- 
maticus  and  status  epilepticus.  These  agents 
have  no  bronchodilating  or  anticonvulsants 
properties  and  their  use  in  these  settings  can 
be  harmful  to  a  patient.  It  is  currently  rec- 
ommended that  these  agents  be  avoided  in 
patients  with  these  conditions. 

In  Chapter  19,  "Cardiac  Drugs,"  there  is 
no  discussion  of  dopamine  under  the  sec- 
tion on  cardiotonic  (positive  inotropic) 
drugs.  In  Chapter  20,  there  is  no  discussion 
of  the  low  molecular  weight  heparins  in  the 
section  on  anticoagulants.  In  the  reference 
list  at  the  end  of  the  chapter,  the  review 
article  for  the  hypertensive  emergencies 
dates  back  to  1986. 

Chapter  22,  "Drugs  Affecting  the  Cen- 
tral Nervous  System,"  is  extremely  outdated. 
There  is  an  extensive  discussion  of  the  clin- 
ical pharmacology,  mechanism  of  action, 
clinical  effects,  clinical  uses,  and  overdose 
barbiturates.  Unfortunately,  these  agents  are 
rarely  used  in  clinical  practice.  The  discus- 
sion of  benzodiazepines  is  limited  to  sev- 
eral paragraphs. 

The  book's  general  appearance  is  quite 
nice.  There  are  few  typographical  errors. 
The  clarity  of  the  illustrations — one  of  the 
book's  strengths — is  outstanding,  signifi- 
cantly enhance  the  text,  and  help  to  clarify 
the  discussions  in  the  text.  In  general,  the 
references  are  up  to  date  and  cite  the  most 
current  recommendations  that  were  avail- 
able when  the  book  went  to  press.  Although 


Respiratory  Care  •  June  99  Vol  44  No  6 


703 


Books,  Films,  Tapes,  &  Software 


some  of  the  references  seem  to  be  outdated, 
they  are  appropriate  for  the  topics  being  dis- 
cussed. The  index  is  easy  to  use  and  accu- 
rate. 

hi  summary,  this  book  is  geared  to  the 
entry-level  respiratory  therapy  student.  The 
chapters  dealing  with  respiratory  care  phar- 
macology are  superficial,  but  well  written 
for  the  entry-level  student.  The  remainder 
of  the  book  should  be  avoided  because  of 
the  antiquated  examples,  misleading  infor- 
mation, and  errors.  Information  on  the  med- 
ications not  directly  related  to  the  respira- 
tory system  should  be  obtained  from  more 
traditional  pharmacology  or  subspecialty 
textbooks. 

Gregory  M  Susia  PharmD 

Clinical  Center  Pharmacy  Department 

National  Institutes  of  Health 

Bethesda,  Maryland 

Cardiopulmonary  Critical  Care,  3"'  ed. 

David  R  Dantzkcr  MD  and  Steven  M  Schaif 
MD  PhD,  Editors.  Hardcover,  illustrated, 
692  pages.  Philadelphia:  W  B  Saunders  Co; 
1998.  $125.00. 

The  third  edition  of  Cardiopulmonary 
Critical  Care,  edited  by  David  R  Dantzker 
and  Steven  M  Scharf,  is  a  scholarly  and 
highly  technical  review  of  the  pathophysi- 
ology of  diseases  of  the  cardiac  and  pulmo- 
nary system.  The  first  10  chapters  are  com- 
pletely devoted  to  pathophysiology,  while 
the  subsequent  chapters  focus  on  principles 
of  treatment,  including  mechanical  ventila- 
tion, cardiopulmonary  resuscitation,  and  di- 
agnostic radiology.  The  book  concludes  with 
comprehensive  and  practical  reviews  of  spe- 
cific disorders  of  the  cardiac  and  pulmonary 
system:  acute  myocardial  infarction,  dys- 
rhythmias, acute  respiratory  distress  syn- 
drome, sepsis,  pneumonia,  thromboembolic 
disease,  obstructive  airways  diseases,  hy- 
perbaric medicine,  and  high  altitude  pulmo- 
nary failure. 

The  editors  state  in  their  preface  that  they 
intend  to  provide  insights  into  the  patho- 
physiology of  diseases  of  the  cardiopulmo- 
nary system;  to  describe  advances  in  bio- 
medical science,  diagnostics,  and 
therapeutics;  and  to  provide  a  detailed  dis- 
cussion of  selected,  important,  difficult-to- 
nianage  diseases.  I  believe  they  have 
achieved  these  goals  on  all  counts.  The  chap- 
ters on  pathophysiology  provide  an  in-depth 
and  topical  discussion  of  cardiopulmonary 
function  and  dysfunction  in  the  critical  care 
setting.  The  chapter  on  the  pathogenesis  of 


acute  lung  injury  has  excellent  figures  and 
summary  tables,  and  comprehensively  re- 
views definitions,  inflammatory  mediators, 
and  cellular  events.  The  chapter  even  men- 
tions the  more  recently  described  role  of 
nitric  oxide,  adherence  molecules,  and  glu- 
cocorticoids in  late-phase  acute  respiratoiy 
distress  syndrome.  I  was  impressed  to  tlnd 
that  the  chapter  on  the  pulmonary  vascular 
bed  contains  very  recent  hypotheses  about 
the  role  of  nitric  oxide  in  hypoxic  pulmo- 
nary vasoconstriction  and  emerging  data  on 
the  role  of  hemoglobin  in  carrying  nitric 
oxide  to  the  microcirculation.  The  chapter 
on  oxygen  transport  and  utilization  proffers 
an  excellent  review  of  hemoglobin  function, 
oxygen  consumption,  and  the  ongoing  de- 
bate about  oxygen  supply  dependence  in 
critical  illness.  The  chapters  maintain  a  fo- 
cus on  critical  illness  with  one  exception. 
The  chapter  on  microcirculatory  flow  is  per- 
haps too  technical,  focusing  heavily  on  one 
research  group's  methods,  and  in  my  opin- 
ion would  be  more  appropriate  for  a  journal 
publication  than  for  a  review  textbook. 

Two  brief  chapters  on  mechanical  ven- 
tilation and  critical  care  radiology  are  well 
organized,  and  the  radiology  chapter  is  re- 
plete with  images  that  illustrate  most  of  the 
issues  covered.  The  chapters  on  specific  dis- 
ease states  are  well  organized,  clearly  writ- 
ten, well  referenced,  and  provide  detailed 
information  beyond  the  scope  of  most  re- 
view texts.  The  chapter  on  thromboembolic 
disease  provides  useful  decision  algorithms 
for  the  evaluation  of  suspected  deep  venous 
thrombosis  and  pulmonary  embolism,  in- 
cluding new  information  on  the  D-dimer 
assay,  the  role  of  serial  impedance  plethys- 
mography or  compression  duplex  ultrasound 
in  patients  with  adequate  cardiopulmonary 
reserve,  and  low  molecular  weight  heparin. 
The  chapter  on  asthma  covers  epidemiol- 
ogy, cellular  and  mediator  events,  clinical 
markers  of  severity,  and — relevant  to  the 
intensivist — reviews  mechanical  ventilation 
and  inhaled  helium-oxygen  mixtures. 

In  conclusion.  I  can  strongly  recommend 
this  book  to  the  physician,  therapist,  or  nurse 
seeking  a  scholarly,  thorough  review  of  the 
pathophysiology  of  the  cardiopulmonary 
system  and  specific  common  diseases  seen 
in  the  intensive  care  unit.  A  reader  who  wants 
a  light,  brief  review  of  critical  care  medi- 
cine should  look  elsewhere.  The  chapters  of 
this  book  are  comprehensive  and  dense  with 
information.  The  book  will  definitely  sat- 
isfy the  reader  in  search  of  a  more  substan- 


tive discussion  of  diseases  common  to  the 
intensive  care  unit. 

Mark  T  Gladwin  MD 

Critical  Care  Department 

National  Institutes  of  Health 

Bethesda,  Maryland 

One  Minute  Asthma:  What  You  Need  to 
Know,  4'"  ed.  Thomas  F  Plant  MD.  Soft- 
cover,  illustrated,  56  pages.  Amherst  MA: 
Pedipress  Inc;  1998.  $5.00. 

This  short  booklet  briefly  outlines  vari- 
ous aspects  of  asthma — the  signs  and  symp- 
toms, various  asthma  triggers,  and  medica- 
tions used  in  the  treatment  of  the  disease. 
The  booklet  would  be  useful  as  a  home  ref- 
erence and  is  intended  primarily  for  patients 
and  for  parents  of  children  with  a  new  di- 
agnosis of  asthma.  It  would  also  be  of  use  to 
primary  care  physicians,  pulmonologists, 
and  any  health  educator  as  a  framework 
to  further  patients'  understanding  about  the 
disease. 

The  author's  goal  is  to  give  "asthma  pa- 
tients the  facts  about  their  disease."  The  au- 
thor does  a  good  job  of  defining  asthma. 
The  material  is  well  selected  for  a  booklet 
of  this  size  and  is  presented  in  an  organized 
fashion,  moving  from  basic  pathophysiol- 
ogy in  a  layperson's  terms  to  asthma  trig- 
gers. The  author  extensively  describes  the 
various  medications  used,  along  with  com- 
mon side  effects.  The  book  is  somewhat 
disjointed  in  the  beginning  but  picks  up  about 
a  fourth  of  the  way  through  and  subsequently 
fiows  well.  The  descriptions  are  clear  and 
accurate.  The  pathophysiology  of  asthma  is 
written  very  simply  and  is  quite  understand- 
able for  those  not  in  the  medical  field.  The 
instructions  for  metered  dose  inhaler  use  and 
peak  flow  monitoring  are  well  written  and 
very  clear. 

However,  the  overall  tone  of  the  booklet 
is  one  of  absolutes  and  can  give  the  impres- 
sion that  asthma  is  always  very  straightfor- 
ward and  easy  to  treat.  Under  the  statement, 
"Asthma  should  not  slow  you  down,"  the 
author  should  put  a  disclaimer  to  indicate 
that  the  severity  of  asthma  varies  extensively 
from  person  to  person — some  individuals 
will  need  closer  monitoring  and  more  med- 
ications. The  text  on  Page  6  suggests  that  as 
long  as  you  work  out  a  "better  plan,"  you 
can  control  asthma.  This  may  indeed  be  tme 
for  many  asthmatics,  but  there  is  a  subset  of 
patients  for  whom  this  will  not  hold  true. 
This  is  the  group  usually  referred  to  a  pul- 


704 


Respiratory  Care  •  June  99  Vol  44  No  6 


I 


monologist.  and  patients  should  be  aware  of 
this  lest  they  be  lulled  into  a  false  sense  of 
complacency. 

I  also  disagree  with  the  author's  sugges- 
tion that  at  every  opportunity  a  "good  asthma 
doctor  will  check  peak  flows  or  pulmonary 
function  tests"  in  a  patient  with  asthma. 
Some  physicians  examine  their  patients'  di- 
aries for  trends  or  do  not  feel  peak  flows  are 
very  reliable  and  therefore  do  not  use  them 
extensively.  There  are  many  practice  styles; 


Books,  Films,  Tapes,  &  Software 


patients  should  be  encouraged  to  find  a  phy- 
sician whose  style  meets  their  needs. 

Overall,  the  book  is  an  excellent  intro- 
duction to  asthma  for  the  novice  with  the 
caveats  as  listed  above.  The  book  is  en- 
hanced by  very  clear  illustrations;  especially 
noteworthy  are  those  representing  the  air- 
ways in  asthma  and  the  use  of  metered  dose 
inhalers.  At  the  end  of  the  book,  which  is 
also  available  in  Spanish,  the  author  refers 
to  several  other  books  he  has  written  on 


asthma  and  also  includes  a  listing  of  orga- 
nizations and  newsletters  that  the  individual 
can  access  for  further  infonnation. 

Yolanda  Mageto  MD 

Senior  Fellow 

Division  of  Pulmonary  and 

Critical  Care  Medicine 

Department  of  Medicine 

University  of  Washington 

Seattle,  Washington 


I 


Respiratory  Care  •  June  99  Vol  44  No  6 


705 


Q^tiX^if/^^ for  Americm  Association  of 
Respiratory  Care  subscribers... 


OrdtT  (his  book  loday  and  take  "I \J      off  the  list  price 
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Physiological  Basis  of 
Ventilatorjr  Support 


(Lung  Biology  in  Health  and  Disease  Series/ 118) 
edited  by 

John  J.  Marini 

University  of  Minnesota  and  St.  Paul  Ramsey  Medical  Center, 
St.  Paid,  Minnesota 

Arthur  S.  Slutsky 

University  of  Toronto  and  Mount  Sinai  Hospital, 
Toronto,  Ontario,  Canada 

1998  /  1480  pp.,  illus.  /  ISBN:  0  8247  9861  9  / 
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CONTENT. 


^Section  Headings  Only) 


Physiology  Underlying  Ventilatory  Support 

Control  of  Breathing  and  Respiratory 

Muscle  liinction 
Rt'spiratoiy  Mcclianics 
Gas  Exdianjit' 

Consequences  of  Mechanical 
Ventilation 

Ventilation-Related  Consequences 
Non- Ventilation-Related  Consequences 

Implementing  Ventilatory  Support 

Initiating  Mechanical  Ventilation 
Modes  of  Ventilatory  Support 
Adjunctive  Methods  and  Approaches 

Specific  Problems  in  Ventilation 


Physiological 
Basis  of  Ventilory 
Support 


JohnJ.  Mafln) 
Arthurs.  Slutsky 


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UNIFORM 

REPORTING 


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for  Acute  Care 

The  Uniform  Reporting  Manual 

provides  you  with  nationally  recognized 

standards  for  documenting  v^rorkload 

units  and  time  standards.  Includes 

patient  assessment 

activities  covering  bronchial 

hygiene,  supplemental  oxygen, 

airway  care,  diagnostic  tests,  and 

cardiovascular  diagnostics.  In 

addition,  there  are  chapters  on  "Clinical 

Activities  Without  Time  Standard"  and 

"Management  Support  Activities." 

Authored  by  the  AARC  in  1990, 

updated  1 993.  Binder,  1 65  pages. 

ItemBKI    $65 
($85  nonmembers) 

Add  $5  for  shipping 

Call  (972)  243-2272  or 

fax  your  order  to 

(972)484-6010 


Visit  our  website  at:  www.aarc.org 

American  .Association  forRespiratory  Care 

11030  Abies  Ln.,  Dallas,  TX  75229-4593 

Texas  customers  only,  please  add  8.25%  sales  tax 

(inctudmg  shipping  charges).  Texas  customers  that  are 

exempt  from  sales  tax  must  attach  an  exemption 

certificate.  Prices  subject  to  change  without  notice. 


Circle  102  on  reader  service  card 


CPG  1 

CPG  2 
CPG  3 
CPG  4 
CPG  5 
CPG  6 

CPG  7 

CPG  8 
CPG  9 


CPG  10 
CPG  11 
CPG  12 
CPG  13 
CPG  14 
CPG  15 

CPG  16 

CPG  17 

CPG  18 
CPG  19 

CPG20 
CPG21 
CPG22 
CPG23 

CPG24 

CPG25 
CPG26 


Spirometry,  1996  Update  •  $1 

Oxygen  Therapy  in  Acute  Care  Hospital  •  $1 

Nasotracheal  Suctioning  •  $1 

Patient-Ventilator  System  Checks  •  $1 

Directed  Cough  ■  $1 

In-Vitro  pH  and  Blood  Gas  Analysis  and 

Hemoximetry  •  $1 

Use  of  Positive  Airway  Pressure  Adjuncts  to 

Bronchial  Hygiene  Therapy  •  $1 

Sampling  for  Arterial  Blood  Gas  Analysis  •  $1 

Endotracheal  Suctioning  of  Mechanically 

Ventilated  Adults  and  Children  with  Artificial 

Airways  •  $1 

Incentive  Spirometry  •  $1 

Postural  Drainage  Therapy  •  $1 

Bronchial  Provocation  •  $1 

Selection  of  Aerosol  Delivery  Device  ■  $1 

Pulse  Oximetry  •  $1 

Single-Breath  Carbon  Monoxide  Diffusing 

Capacity,  1999  Update-  $1 

Oxygen  Therapy  in  the  Home  or  Extended  Care 

Facility  •  $1 

Exercise  Testing  for  Evaluation  of  Hypoxemia 

and/or  Desaturation  ■  $1 
Humidification  during  Mechanical  Ventilation  ■  $1 
Transport  of  the  Mechanically  Ventilated 
Patient  •  $1 

Resuscitation  in  Acute  Care  Hospitals  •  $1 
Bland  Aerosol  Administration  •  $1 
Fiberoptic  Bronchoscopy  Assisting  ■  $1 
Intermittent  Positive  Pressure  Breathing 
(IPPB)  ■  $1 

Application  of  CPAP  to  Neonates  Via  Nasal 
Prongs  or  Nasopharyngeal  Tube  •  $1 
Delivery  of  Aerosols  to  the  Upper  Airway  •  $1 
Neonatal  Time-Triggered,  Pressure-Limited, 
Time-Cycled  Mechanical  Ventilation  •  $1 


'CPG27       Static  Lung  Volumes  ■  $1 
CP628       Surfactant  Replacement  Therapy  •  $1 
CPG29      Ventilator  Circuit  Changes  ■  $1 
CPG30       Metabolic  Measurement  using  Indirect 

Calorimetry  during  Mechanical  Ventilation 
CPG31       Transcutaneous  Blood  Gas  Monitoring  for 

Neonatal  &  Pediatric  Patients  ■  $1 
CPG32       Body  Plethysmography  •  $1 
CPG33       Capillary  Blood  Gas  Sampling  for  Neonatal  & 

Pediatric  Patients  •  $1 
CPG34      Defibrillation  during  Resuscitation  •  $1 
CPG35       Infant/Toddler  Pulmonary  Function  Tests  •  $1 
CPG3G       Management  of  Airway  Emergencies  ■  $1 
CPG37      Assessing  Response  to  Bronchodilator  Thera| 

Point  of  Care-  $1 
CPG38       Discharge  Planning  for  the  Respiratory  Care" 

Patient  -  $1 
CPG39       Long-Term  Invasive  Mechanical  Ventilation  in  the 

Home  -  $1 
CPG40       Capnography/Capnometry  during  Mechanical 

Ventilation  -  $1 
CPG41       Selection  of  an  Aerosol  Delivery  Device  for 

Neonatal  and  Pediatric  Patients  -  $1 
CPG42       Polysomnography  -  $1 
CPG43       Selection  of  an  Oxygen  Delivery  Device  for 

Neonatal  and  Pediatric  Patients  -  $1 
CPG44       Selection  of  a  Device  for  Delivery  of  Aerosol  to 

the  Lung  Parenchyma  -  $1 
CPG45      Training  the  Health-Care  Professional  for  the  Role 

of  Patient  and  Caregiver  Educator  •  $1 
CPG4B       Providing  Patient  and  Caregiver  Training  -  $1 
CPG47       Removal  of  the  Endotracheal  Tube  -  $1 
CPG48       Suctioning  of  the  Patient  in  the  Home  -  $1 
CPG49       Selection  of  Device,  Administration  of 

Bronchodilator,  and  Evaluation  of  Response  to 

Therapy  in  Mechanically  Ventilated  Patients  •  $1 


CPG93  -  Complete  Set  in  Binder  •  $35 

($60  AARC  nonmembers) 
(+$7.00  for  Shipping  and  Handling) 


j^ 


American  Association  for  Respiratory  Care 
11030  Abies  Ln.,  Dallas,  TX  75229-4593,  www.aarc.org 

Call  (972)  243-2272  or  fax  to  (972)  484-2720 

with  MasterCard,  Visa,  or  Purctiase  Order  Number 


Texas  customers  only,  please  add  8,25%  sales  tax  (including  shipping  charges).  Texas  customers  that  are  exempt  from  sales  tax  must  attach  an  exemption  certificate.  Prices  subject  to  change  wit  i.-uf  notice. 


News  releases  about  new  products  and  services  will  be  considered  for  publication  in  this  section. 

There  is  no  charge  for  these  listings.  Send  descriptive  release  and  glossy  black  and  white  photographs 

to  RESPIRATORY  CARE.  New  Products  &  Services  Dept.  1 1030  Abies  Lane.  Dallas  TX  75229-4593. 

The  Reader  Service  Card  can  be  found  at  the  back  of  the  Journal. 


New  Products 
&  Services 


Ventilator  Antidisconnect  Device.  Wen- 
Mar  Designs  Inc  introduces  the  WenMar 
Bridie,  an  antidisconnect  device  for  ven- 
tilator tubing.  WenMar  says  the  device  is 
adjustable  and  provides  assurance  that  tub- 
ing will  stay  securely  in  place  regardless 
of  repositioning  the  patient,  a  strong  cough, 
or  a  high  PEEP.  For  more  information 
from  WenMar  Designs,  circle  number  1 99 
on  the  reader  service  card  in  this  issue,  or 
send  your  request  electronically  via 
"Advertisers  Online"  at  http://www.aarc. 
org/buyers_guide/ 


Pulse  Oximeter/ECG  Monitor.  BCl  Inter- 
national has  introduced  the  Autocorr^^'^ 
Plus,  with  3-  or  5-lead  ECG,  pace  detect, 
digital  oximetry  with  SAC^"^  (Serial  Auto- 
correlation) technology,  and  respiration. 
BCI  International  says  the  Autocorr  Plus 
is  fourth  in  the  Clarity®  series  and  is  a  cost- 
effective,  versatile  monitor  that  can  be  used 


as  a  stand-alone  device  or  can  be  combined 
with  other  Clarity  Systems  for  multi-param- 
eter monitoring.  The  company  says  a  high- 
resolution  electroluminescent  display  pro- 
vides two  user  configurable  traces  and  say 
the  device  is  easily  portable.  For  more 
information  from  BCI  International,  cir- 
cle number  152  on  the  reader  service  card 
in  this  issue,  or  send  your  request  elec- 
tronically via  "Advertisers  Online"  at 
http://www.aarc.org/buyers_guide/ 


Portable  Suction  Unit.  Precision  Med- 
ical offers  the  EASY  GO  VAC  portable 
suction  unit  which,  according  to  the  com- 
pany, provides  twice  the  normal  power 
and  battery  life  of  other  portable  units. 
Precision  Medical  says  the  device  is  an 
AC/DC  portable  suction  unit  that  can  uti- 
lize any  standard  canister  and  incorporates 
many  safety  features  including  double 
overflow  protection,  a  low  battery  light, 
and  the  ability  to  be  recharged  while  in 
its  carrying  case.  For  more  information 
from  Precision  Medical,  circle  number  151 
on  the  reader  service  card  in  this  issue,  or 
send  your  request  electronically  via 
"Advertisers  Online"  at  http://www.aarc. 
org/buyers_guide/ 


Blood  Gas/Oximeter.  Nova  Biomedical 
has  introduced  the  Stat  Profile®  pHOxTM. 
The  company  says  this  device  measures 
oxygen  saturation  (S02%),  hemoglobin, 
and  hematocrit  as  well  as  the  standard 
blood  gas  menu  of  pH,  pC02,  and  pOi. 
According  to  Nova  Biomedical,  the  Stat 
Profile  pHOx  analyzer  provides  the  six-test 
blood  gas/oxygenation  menu  without  a  sep- 
arate CO-Oximeter  analysis  at  the  same 
cost  as  a  standard  three-test  menu.  Com- 
pany literature  says  the  six-test  panel 
requires  only  70  |iL  of  whole  blood,  and 
the  three-test  panel  only  40  pL  and  adds 
that  the  device  uses  a  liquid-only  calibration 
system  that  eliminates  the  compressed  gas 
tanks,  regulators,  gas  tubing  lines,  and 
humidifier  chambers  seen  on  conventional 
blood  gas  analyzers.  For  more  information 
from  Nova  Biomedical  circle  number  200 
on  the  reader  service  card  in  this  issue,  or 
send  your  request  electronically  via 
"Advertisers  Online"  at  http://www.aarc. 
org/buyers_guide/ 


708 


RESPIRATORY  CARE  •  JUNE   1 999  VOL  44  NO  6 


MEI^JfccH 


For  VOLUNTARY  reporting 

by  health  professionals  of  adverse 

events  and  product  problems 


Form  Approved:  0MB  No.  I)91(M)291  Expires:  4/3(VM 
See  0MB  statement  on  reverse 
FDA  Use  Only  (Resp  Care) 


THE    FDA    MEDICAL   PRODUCTS   REPORTrNG    PROGRAM 


A.  Patient  information 


1    Patient  Identifier 


In  confidence 


2   Age  at  time 
of  event: 

or  


Date 
of  birtti: 


3  Sex 

I     I  female 
I    I  male 


Page 


4.  Weiglit 


of 


Triage  unit 
sequence  i 


-lbs 


kgs 


B.  Adverse  event  or  product  problem 


1,  LJ  Adverse  event      and/or  Lj  Product  problem  (e.g.,  defects/malfunctions) 


2   Outcomes  attributed  to  adverse  event 

(check  all  that  apply) 

□  death    

|mo/day/yr) 

I     I  life-threatening 

I     I  hospitalization  -  initial  or  prolonged 


I    I  disability 

I     I  congenital  anomaly 

I     I  required  intervention  to  prevent 
permanent  impairment/damage 

n  other: 


3  Date  of 
event 

(mo/day/yO 


5    Describe  event  or  problem 


4  Date  of 
this  report 


6.  Relevant  tests/laboratory  data,  including  dates 


7.  Other  relevant  history,  Including  preexisting  medical  conditions  (e.g..  allergies, 
race,  pregnancy,  smoking  and  alcohol  use,  hepatic/renal  dysfunction,  etc.) 


Mall  to:    MEdWatch  or  FAX  to: 

5600  Fishers  Lane  1 -800-FDA-01 78 

Rockville,  MD  20852-9787 


C.  Suspect  medication(s) 


1 .  Name  (give  labeled  strength  &  mfr/labeler,  if  known) 
#1 


#2 


2.  Dose,  frequency  &  route  used 

#1 

#2 


3.  Therapy  dates  (if  unknown,  give  duration) 

from/10  lor  best  estimate) 
#1 


#2 


4.  Diagnosis  for  use  (indication) 
#1 


#2 


6.  Lot  #  (if  known) 
#1 


7.  Exp.  date  (if  known) 

#1 

#2 


9.  NDC  #  (for  product  problems  only) 


5.   Event  abated  after  use 
stopped  or  dose  reduced 

*1  Dyes  Dno    ngg^Py"'' 


#2  Dyes  D  no    D^'' 


6    Event  reappeared  after 
relntroductlon 

#1  Dyes  Dno   Dgg^Py"'' 


#2  Dyes  Dho    Dig^Py"'' 


10.  Concomitant  medical  products  and  therapy  dates  (exclude  treatment  of  event) 


D.  Suspect  medical  device 


1    Brand  name 


2   Type  of  device 


3    Manufacturer  name  &  address 


6. 
model  #  _ 

catalog  # 

serial  # 

lot#  


other  # 


4.  Operator  of  device 

I    I  health  professional 
I    I  lay  user/patient 
□  other: 


5.   Expiration  date 

(mo/day/yr) 


7.   If  Implanted,  give  date 

(mo/day/yr) 


8.    If  explanted,  give  date 

(mo/day/yr) 


9    Device  available  for  evaluation?               (Do  not  send  to  FDA) 
I     I    yes  LJ  ho  Lj  returned  to  manufacturer  on 


10.  Concomitant  medical  products  and  therapy  dates  (exclude  treatment  of  event) 


E.    Reporter  (see  confidentiality  section  on  back) 


1 .    Name  &  address 


phone  # 


2.  Health  professional? 

□  yes       □    no 


3.    Occupation 


5      If  you  do  NOT  want  your  Identity  disclosed  to 
the  manufacturer,  place  an  "  X  "  In  this  box.      Q 


4.  Also  reported  to 

I     I      manufacturer 
I    I      user  facility 
I     I      distributor 


=DA  Form  3500  1/9«) 


Submission  of  a  report  does  not  constitute  an  admission  that  medical  personnel  or  the  product  caused  or  contributed  to  the  event. 


ADVICE  ABOUT  VOLUNTARY  REPORTING 


Report  experiences  with: 

•  medications  (drugs  or  biologies) 

•  medical  devices  (including  in-vitro  diagnostics) 

•  special  nutritional  products  (dietary 
supplements,  medical  foods,  infant  formulas) 

•  otfier  products  regulated  by  FDA 

Report  SERIOUS  adverse  events.  An  event 
is  serious  when  the  patient  outcome  is: 

•  death 

•  life-threatening  (real  risk  of  dying) 

•  hospitalization  (initial  or  prolonged) 

•  disability  (significant,  persistent  or  permanent) 

•  congenital  anomaly 

•  required  intervention  to  prevent  permanent 
impairment  or  damage 

Report  even  if: 

•  you're  not  certain  the  product  caused  the 
event 

•  you  don't  have  all  the  details 

Report  product  problems  -  quality,  performance 
or  safety  concerns  such  as: 

•  suspected  contamination 

•  questionable  stability 

•  defective  components 

•  poor  packaging  or  labeling 

•  therapeutic  failures 


How  to  report: 

•  just  fill  in  the  sections  that  apply  to  your  report 

•  use  section  C  for  all  products  except 
medical  devices 

•  attach  additional  blank  pages  if  needed 

•  use  a  separate  form  for  each  patient 

•  report  either  to  FDA  or  the  manufacturer 
(or  both) 


Important  numbers: 

•  1-800-FDA-0178 

•  1-800-FDA-7737 

•  1-800-FDA-1088 


1  -800-822-7967 


to  FAX  report 

to  report  by  modem 

to  report  by  phone  or  for 

more  information 

for  a  VAERS  form 

for  vaccines 


If  your  report  involves  a  serious  adverse  event 
with  a  device  and  it  occurred  in  a  facility  outside  a  doc- 
tor's office,  that  facility  may  be  legally  required  to  report  to 
FDA  and/or  the  manufacturer.  Please  notify  the  person  in 
that  facility  who  would  handle  such  reporting. 

Confidentiality:  The  patient's  identity  is  held  in  strict 
confidence  by  FDA  and  protected  to  the  fullest  extent  of 
the  law.  The  reporter's  identity,  including  the  identity  of  a 
self-reporter,  may  be  shared  with  the  manufacturer  unless 
requested  otherwise.  However,  FDA  will  not  disclose  the 
reporter's  identity  in  response  to  a  request  from  the 
public,  pursuant  to  the  Freedom  of  Information  Act. 


The  public  reporting  burden  tor  this  collection  of  intormation 
has  been  estimated  to  average  30  minutes  per  response, 
including  the  time  for  reviewing  instructions,  searching  exist- 
ing data  sources,  gathering  and  maintaining  the  data  needed, 
and  completing  and  reviewing  the  collection  of  information. 
Send  comments  regarding  this  burden  estimate  or  any  other 
aspect  of  this  collection  of  information,  including  suggestions 
for  reducing  this  burden  to: 


DHHS  Reports  Clearance  Otflce 
Paperworlf  Reduction  Project  (0910-0291) 
Hubert  H,  Humphrey  Building.  Room  531-H 
200  Independence  Avenue.  S.w. 
Washington.  DC  20201 


An  agency  may  not  conduct  or  sponsor, 
and  a  person  is  not  required  to  respond  to. 
a  collection  of  information  unless  It  displays 
a  currently  valid  OMB  control  number." 


Please  do  NOT 
return  tliis  form 
to  either  of  these 
addresses. 


U.S.  DEPARTMENT  OF  HEALTH  AND  HUMAN  SERVICES 
Public  Health  Service  •  Food  and  Drug  Administration 


FDA  Form 35ooback       Plcasc  Usc  Addfcss  Provldecl  Below  -  Just  Fold  In  Thirds,  Tape  and  Mail 


Department  of 

Health  and  Human  Services 

Public  Health  Service 

Food  and  Drug  Administration 

Rockville,  MD  20857 

Official  Business 

Penalty  for  Private  Use  $300 


BUSINESS  REPLY  MAIL 

FIRST  CLASS  MAIL    PERMIT  NO.  946    ROCKVILLE,  MD 


POSTAGE  WILL  BE  PAID  BY  FOOD  AND  DRUG  ADMINISTRATION 


mel)s)^tch 


The  FDA  Medical  Products  Reporting  Program 
Food  and  Drug  Administration 
5600  Fishers  Lane 
Rockville,  MD  20852-9787 


NO  POSTAGE 

NECESSARY 

IF  MAILED 

IN  THE 

UNITED  STATES 

OR  APO/FPO 


iMl.lll.Mlnlnl.liMlillilnlinllMlilnilMlill 


American  Association  for  Respiratory  Care 


^\j^j^ij  d^\-yj  uj} 


Please  read  the  eligibility  requirements  for  each  of  the  classifications  in  the 
right-hand  column,  then  complete  the  applicable  section.  All  information 
requested  below  must  be  provided,  except  where  indicated  as  optional. 
See  other  side  for  more  information  and  fee  schedule.  Please  sign  and  date 
application  on  reverse  side  and  type  or  print  clearly.  Processing  of  applica- 
tion takes  approximately  15  days. 

n  Active 
Associate 

n  Foreign 

n   Physician 

D  Industrial 
n  Special 
D  Student 


Last  Name  _ 
First  Name 


Social  Security  No. 

Home  Address 

City 


State 


.Zip 


Phone  No.  ( . 


Primary  Job  RBsponsibility  fcheclr  one  onlyf 

D  Technical  Director 

D  Assistant  Technical  Director 

n  Pulmonary  Function  Specialist 

n  Instructor/Educator 

D  Supervisor 

□  Staff  Therapist 

D  Staff  Technician 

n  Rehabilitation/Home  Care 

n  Medical  Director 

n  Sales 

D  Student 

n  Other,  specify 


Type  of  Busfnoss 

n  Hospital 

n  skilled  Nursing  Facility 

D  DME/HME 

n  Home  Health  Agency 

n  Educational  Institution 

D  Manufacturer  or  supplier 

j .  D  Other,  specify 


Date  of  Birth  (optional) 


Sex  (optional) . 


U.S.  Citizen? 


Yes 


No 


Have  you  ever  been  a  member  of  the  AARC? 
If  so,  when?  From 


to 


Preferred  mailing  address:    D  Home    D  Business 


For  office  use  only 


FOR  ACTIVE  MEMBER 

An  individual  is  eligible  if  he/she  lives  in  the  U.S.  or  its  territories  or  was  an  Active  Member 
prior  to  moving  outside  its  borders  or  territories,  and  meets  ONE  of  the  following  criteria:  M )  is 
legally  credentialed  as  a  respiratory  core  professionol  if  employed  in  a  state  that  manaates 
such,  OR  (21  is  a  graduate  or  on  accredited  educotional  program  in  respiratory  care,  OR  [3] 
holds  a  creaential  issued  by  the  NBRC.  An  individual  who  is  an  AARC  Active  Member  in  good 
standing  on  December  8,  1 994,  will  continue  as  such  provided  his/her  membership  remains  in 
good  stonding. 

PLEASE  USE  THE  ADDRESS  OF  THE  LOCATION  WHERE  YOU  PERFORM  YOUR  JOB,  NOT 
THE  CORPORATE  HEADQUARTERS  IF  IT  IS  LOCATED  ELSEWHERE. 

Place  of  Employment 

Address 

City 

State 


-Zip 


Phone  No. 


Medical  Director/Medical  Sponsor . 


FOR  ASSOCIATE  OR  SPECIAL  MEMBER 

Individuals  who  hold  a  position  related  to  respiratory  care  but  do  not  meet  the  requirements  of 
Active  Member  shall  be  Associate  Members.  They  hove  oil  the  rights  and  benefits  of  the  Asso- 
ciation except  to  hold  office,  vote,  or  serve  as  chair  of  a  standing  committee.  The  following  sub- 
classes of  Associate  Membership  are  available:  Foreign,  Physician,  and  Industrial  (individuals 
whose  primory  occupation  is  directly  or  indirectly  devoted  to  the  manufocture,  sale,  or  distribu- 
tion of  respiratory  care  eauipmenf  or  supplies).  Speciol  Members  are  those  not  working  in  a 
respiratory  core-related  field. 

PLEASE  USE  THE  ADDRESS  OF  THE  LOCATION  WHERE  YOU  PERFORM  YOUR  JOB,  NOT 
THE  CORPORATE  HEADQUARTERS  IF  IT  IS  LOCATED  ELSEWHERE. 

Place  of  Employment 

Address 

City 

State 


-Zip 


Phone  No. 


FOR  STUDENT  MEMBER 

Individuals  will  be  classified  as  Student  Members  if  they  meet  all  the  requirements  for  Associate 
Membership  and  are  enrolled  in  an  educational  program  in  respiratory  care  accredited  by,  or 
in  the  process  of  seeking  accreditation  from,  an  AARC-recognized  agency. 

SPECIAL  NOTICE  —  Student  Members  do  not  receive  Continuing  Respiratory  Core  Education 
(CRCE)  transcripts.  Upon  completion  of  your  respiratory  care  education,  continuing  education 
credits  may  be  pursued  upon  your  reclassification  to  Active  or  Associate  Member. 

School/RC  Program 

Address 

City 

State 


-Zip 


Phone  No. 


Length  of  program 

D   1  year 
n  2  years 

Expected  Date  ot  Graduation  (REQUIRED 
INFORMATION) 


n  4  years 

n  Other,  specify  _ 


Month 


Year 


American  Association  for  Respiratory  Care  •  1 1030  Abies  Lane  •  Dallas,  TX  75229-4593  •  [972]  243-2272  •  Fox  [972]  484-2720 


American  Association  for  Respiratory  Care 


DemographU  Questions 

We  request  thaf  you  answer  these  questions  in  order  to  help  us 
design  services  and  programs  to  naeet  your  needs. 


Cheek  the  Highest  Degree  Earned 

□  High  School 

n  RC  Graduate  Technician 


D  Associate  Degree 

D  Bachelor's  Degree 

□  Master's  Degree 

□  Doctorate  Degree 


Number  of  Years  in  Respiratory  Care 

n    11-15  Years 

D    16  years  or  more 


D 

0-2  years 

D 

3-5  years 

n 

6-10  years 

Job  Status 

D 

Full  Time 

D 

Part  Time 

Credentials 

D 

RRT 

n 

CRT 

n 

Physician 

n 

CRNA 

D 

RN 

Salary 

a 

Less  than  $10,000 

D 

$10,001 -$20,000 

D 

$20,001 -$30,000 

a 

$30,001 -$40,000 

D 

$40,000  or  more 

D  LVN/LPN 

n  CPFT 

D  RPFT 

n  Perinatal/Pediatric 


PLEASE  SIGH 

I  hereby  apply  for  membership  in  the  American  Association  for  Respiratory  Care 
and  have  enclosed  my  dues.  If  approved  for  membership  in  the  AARC,  I  will  abide 
by  its  bylaws  and  professional  code  of  ethics.  I  authorize  investigation  of  all  state- 
ments contained  herein  and  understand  that  misrepresentations  or  omissions  of 
facts  colled  for  is  cause  for  reiection  or  expulsion. 

A  yearly  subscription  to  RESPIRATORY  CARE  journal  end  AARC  Times  magazine 
includes  on  allocation  of  $1 1 .50  from  my  dues  for  each  of  these  publications. 

NOTE:  Contributions  or  gifts  to  the  AARC  are  not  tax  deductible  as  charitable  con- 
tributions for  income  tax  purposes.  However,  they  may  be  tax  deductible  as  ordi- 
nary and  necessary  business  expenses  subject  to  restrictions  imposed  as  a  result  of 
association  lobbying  activities.  The  AARC  estimates  that  the  nondeductible  portion 
of  your  dues  —  the  portion  v/hich  is  allocable  to  lobbying  —  is  26%. 


SignafurB 
DaiB 


MBmbership  Fees 

Payment  must  accompany  your  opplication  to  the  AARC.  Fees  are  for  12 
months.  (NOTE:  Renewal  fees  are  $75.00  Active,  Associate-Industrial  or  Associ- 
ate-Physician, or  Special  status;  $90.00  for  Associate-Foreign  status;  and 
$45.00  for  Student  status). 


n  Active 

$  87.50 

n  Associate  (Industrial  or  Physician) 

$  87.50 

D  Associate  (Foreign) 

$102.50 

D  Special 

$  87.50 

D  Student 

$  45.00 

TOTAL 

$ 

Spetialty  Seetions 

Established  to  recognize  the  specialty  areas  of  respiratory  care,  these  sections 
publish  a  bi-monthly  newsletter  that  focuses  on  issues  of  specific  concern  to  that 
specialty.  The  sections  also  design  the  specialty  programming  at  the  national 
AARC  meetings. 

>  D  Adult  Acute  Care  Section 

D  Education  Section 
n  Perinatal-Pediatric  Section 
D  Diagnostics  Section 
n  Continuing  Care- 
Rehabilitation  Section 
D  Management  Section 
□  Transport  Section 
n  Home  Care  Section 
n  Subacute  Core  Section 

TOTAL 

GRAND  TOTAL  =  Membership  Fee 
plus  optional  seetions 


$15.00 

$20.00 

$15.00 

$15.00 

$15.00 

$20.00 

$15.00 

$15.00 

$15.00 

$ 

$ 

n  Total  Amount  Enclosed/Charged       $ 
D  Please  charge  my  dues  (see  below] 

To  charge  your  dues,  complete  the  following: 
D  MasterCard 
D  Visa 

Card  Number 


Card  Expires /_ 

Signature 


Mail  application  and  appropriate  fees  to: 
American  Association  for  Respiratory  Care  •  1 1030  Abies  Lane  •  Dallas,  TX  75229-4593 


[972]  243-2272  •  Fax  [972]  484-2720 


1 


RE/PIRATORy  QiRE 


Manuscript  Preparation  Guide 


General  Information 

Respiratory  Care  welcomes  original  manuscripts  related  to  the 
science  and  technology  of  respiratory  care  and  prepared  accord- 
ing to  these  Instructions  and  the  Uniform  Requirements  for 
Manuscripts  Submitted  to  Biomedical  Journals  [Respir  Care  1997; 
42(6):623-634].  Manuscripts  are  blinded  and  reviewed  by  pro- 
fessionals who  are  experts  in  their  fields.  Authors  are  responsible 
for  all  aspects  of  the  manuscript  and  receive  galleys  to  proofread 
before  publication.  Each  accepted  manuscript  is  copyedited  so  that 
its  message  is  clear  and  it  conforms  to  the  Journal's  style.  Published 
papers  are  copyrighted  by  Daedalus  Inc  and  may  not  be  published 
elsewhere  without  permission. 

Iiditorial  consultation  is  available  at  any  stage  of  planning  or  writ- 
ing. On  request,  specific  guidance  is  provided  for  all  publication  cat- 
egories. To  receive  these  Instructions  and  related  materials,  write 
to  Respiratory  Care,  600  Ninth  Avenue,  Suite  702,  Seattle  WA 
98104,  call  (206)  223-0558,  or  fax  (206)  223-0563. 

Publication  Categories  &  Structure 

Research  Article:  A  report  of  an  original  investigation  (a  study). 
It  includes  a  Title  Page,  Abstract,  Introduction,  Methods,  Results, 
Discussion,  Conclusions,  Product  Sources,  Acknowledgments,  Ref- 
erences, Tables,  Appendices,  Figures,  and  Figure  Captions. 

Evaluation  of  Device/Metliod/Technique:  A  description  and  eval- 
uation of  an  old  or  new  device,  method,  technique,  or  modification. 
It  has  a  Title  Page,  Abstract,  Introduction.  Description  of  De- 
vice/Method/Technique, Evaluation  Methods,  Evaluation  Results, 
Discussion,  Conclusions,  Product  Sources,  Acknowledgments,  Ref- 
erences, Tables,  Appendices,  Figures,  and  Figure  Captions.  Com- 
parative cost  data  should  be  included  wherever  possible. 

Case  Report:  A  report  of  a  clinical  case  that  is  uncommon,  or  was 
managed  in  a  new  way,  or  is  exceptionally  instructive.  All  authors 
must  be  associated  with  the  case.  A  case-managing  physician  must 
either  be  an  author  or  furnish  a  letter  approving  the  manuscript.  Its 
components  are  Title  Page,  Abstract,  Introduction,  Case  Summa- 
ry, Discussion,  References,  Tables,  Figures,  and  Figure  Captions. 

Review  Article:  A  comprehensive,  critical  review  of  the  literature 
and  state-of-the-art  summary  of  a  pertinent  topic  that  has  been  the 
subject  of  at  least  40  published  research  articles.  Title  Page,  Out- 
line, Introduction,  Review  of  the  Literature,  Summary,  Acknowl- 
edgments. References.  Tables,  Appendices,  and  Figures  and  Cap- 
tions may  be  included. 

Overview:  A  critical  review  of  a  pertinent  topic  that  has  fewer  than 
40  published  research  articles. 

Update:  A  report  of  subsequent  developments  in  a  topic  that  has 
been  critically  reviewed  in  this  Journal  or  elsewhere. 


Point-of- View  Paper:  A  paper  expressing  personal  but  substanti- 
ated opinions  on  a  pertinent  topic.  Title  Page,  Text,  References,  Tables, 
and  Illustrations  may  be  included. 

Special  Article:  A  pertinent  paper  not  fitting  one  of  the  foregoing 
categories  may  be  acceptable  as  a  Special  Article.  Consult  with  the 
Editor  before  writing  or  submitting  such  a  paper. 

Editorial:  A  paper  drawing  attention  to  a  pertinent  concern:  it  may 
present  an  opposing  opinion,  clarify  a  position,  or  bring  a  problem 
into  focus. 

Letter:  A  signed  communication,  marked  "For  publication," 
about  prior  publications  in  this  Journal  or  about  other  pertinent  tof)- 
ics.  Tables  and  illustrations  may  be  included. 

Blood  Gas  Comer:  A  brief,  instructive  case  report  involving  blood 
gas  values — with  Questions,  Answers,  and  Discussion. 

Drug  Capsule:  A  mini-review  paper  about  a  drug  or  class  of  drugs 
that  includes  discussions  of  pharmacology,  pharmacokinetics, 
and  pharmacotherapy. 

Graphics  Corner:  A  brief  case  report  incorporating  waveforms  for 
monitoring  or  diagnosis — with  Questions,  Answers,  and  Discussion. 

Kittredge's  Comer:  A  brief  description  of  the  operation  of  respiratory 
care  equipment — with  information  from  manufacturers  and  edito- 
rial comments  and  suggestions. 

PFT  Corner:  Like  Blood  Gas  Comer,  but  involving  pulmonary 
function  tests. 

Cardiorespiratory  Interactions.  A  case  report  demonstrating  the 
interaction  between  the  cardiovascular  and  respiratory  systems.  It 
should  be  a  patient-care  scenario;  however,  the  case — the  central 
theme — is  the  systems  interaction.  CRl  is  characterized  by  figures, 
equations,  and  a  glossary.  See  the  March  1 996  Issue  of  RESPIRA- 
TORY Care  for  more  detail. 

Test  Your  Radiologic  Skill:  Like  Blood  Gas  Corner,  but  involv- 
ing pulmonary  medicine  radiography  and  including  one  or  more  radio- 
graphs; may  involve  imaging  techniques  other  than  conventional 
chest  radiography. 

Review  of  Book,  Film,  Tape,  or  Software:  A  balanced,  critical 
review  of  a  recent  release. 

Preparing  the  Manuscript 

Print  on  one  side  of  white  bond  paper,  8.5  in.  x  1 1  in.  (216  x  279  mm) 
with  margins  of  at  least  1  in.  (25  mm)  on  all  sides  of  the  page.  Use 
double-spacing  throughout  the  entire  manuscript.  Use  a  standard 
font  (eg.  Times,  Helvetica,  or  Courier)  at  least  10  points  in  size,  and 


RESPIRATORY  CARE  Manuscript  Preparation  Guide,  Revised  2/98 


MANUSCRIPT  PREPARATION  GUIDE 


do  not  use  italics  except  for  special  emphasis.  Number  all  pages  in 
upper-right  comers.  Indent  paragraphs  5  spaces.  Do  not  justify.  Do 
not  put  authors'  names,  institutional  affiliations  or  allusions  to 
institutional  affiliations  in  the  text,  or  other  identiflcation  any- 
where except  on  the  title  page.  Repeat  title  only  (no  authors)  on 
the  abstract  page.  Begin  each  of  the  following  on  a  new  page:  Title 
Page,  Abstract,  Text,  Product  Sources  List,  Acknowledgments,  Ref- 
erences, each  Table,  and  each  Appendix.  Use  standard  English  in 
the  first  person  and  active  voice. 

Center  main  section  headings  on  the  page  and  type  them  in  cap- 
ital and  small  letters  (eg.  Introduction,  Methods,  Results,  Discus- 
sion). Begin  subheadings  at  the  left  margin  and  type  them  in  cap- 
ital and  small  letters  (eg.  Patients,  Equipment,  Statistical  Analysis). 

References.  Cite  only  published  works  as  references.  Manuscripts 
accepted  but  not  yet  published  may  be  cited  as  references:  desig- 
nate the  accepting  journal,  followed  by  (in  press),  and  provide  3  copies 
of  the  in-press  article  for  reviewer  inspection.  Cite  references  in  the 
text  with  superscript  numerals.  Assign  numbers  in  the  order  that  ref- 
erences are  first  cited.  On  the  reference  page,  list  the  cited  works 
in  numerical  order.  Follow  the  Journal's  style  for  references.  Abbre- 
viate journal  names  as  in  Index  Medicus.  List  all  authors. 

Article  in  a  journal  carrying  pagination  throughout  volume: 

Rau  JL,  Harwood  RJ.  Comparison  of  nebulizer  delivery  methods 
through  a  neonatal  endotracheal  tube:  a  bench  study.  Respir  Care 
1992;37(11):1233-1240. 

Article  in  a  publication  that  numbers  each  issue  beginning  with 
Page  1: 

Bunch  D.  Establishing  a  national  database  for  home  care.  AARC  Times 
1991;15(Mar):61,62,64. 

Corporate  author  journal  article: 

American  Association  for  Respiratory  Care.  Criteria  for  establish- 
ing units  for  chronic  ventilator-dependent  patients  in  hospitals.  Respir 
Care  1988;33(11):1044-1046. 

Article  in  journal  supplement:  (Journals  differ  in  their  methods  of 
numbering  and  identifying  supplements.  Supply  sufficient  information 
to  promote  retrieval.) 

Reynolds  HY.  Idiopathic  interstitial  pulmonary  fibrosis.  Chest  1986; 
89(3Suppl):I39S-143S. 

Abstract  in  journal:  (Abstracts  citations  are  to  tie  avoided.  Those  more 
than  3  years  old  should  not  be  cited.) 

Stevens  DP.  Scavenging  ribavirin  from  an  oxygen  hood  to  reduce  envi- 
ronmental exposure  (abstract).  Respir  Care  1990;35(11):  1087-1088. 

Editorial  in  journal: 

Enright  P.  Can  we  relax  during  spirometry?  (editorial).  Am  Rev  Respir 
Dis  1993;148(2):274. 

Editorial  with  no  author  given: 

Negative-pressure  ventilation  for  chronic  obstructive  pulmonary  dis- 
ease (editorial).  Lancet  I992;340(8833):1440-1441. 

Letter  in  journal: 

Aelony  Y.  Ethnic  norms  for  pulmonary  function  tests  (letter).  Chest 
199I;99(4):105I. 


Paper  accepted  but  not  yet  published: 

Hess  D.  New  therapies  for  asthma.  Respir  Care  (year,  in  press). 

Personal  author  book:  (For  any  book,  specific  pages  should  be  cited 
whenever  possible.) 

DeRemee  RA.  Clinical  profiles  of  diffuse  interstitial  pulmonary  dis- 
ease. New  York:  Futura;  1990.  p.  76-85. 

Corporate  author  book: 

American  Medical  Association  Department  of  Drugs.  AMA  drug  eval- 
uations, 3rd  ed.  Littleton  CO:  Publishing  Sciences  Group;  1977. 

Chapter  in  book  with  editor(s): 

Pierce  AK.  Acute  respiratory  failure.  In:  Guenter  CA,  Welch  MH,  edi- 
tors. Pulmonary  medicine.  Philadelphia:  JB  Lippincott;  1977:26-42. 

Tables.  Use  consecutively  numbered  tables  to  display  information. 
Start  each  table  on  a  separate  page.  Number  and  title  the  table  and 
give  each  column  a  brief  heading.  Place  explanations  in  footnotes, 
including  all  nonstandard  abbreviations  and  symbols.  Key  the  foot- 
notes with  conventional  designations  (*,  t,  t,  §.  II.  I  **,  tt)  in  con- 
sistent order,  placing  them  superscript  in  the  table  body.  Do  not  use 
horizontal  or  vertical  rules  or  borders.  Do  not  submit  tables  as  pho- 
tographs, reduced  in  size,  or  on  oversize  paper.  Use  the  same  type- 
face as  in  the  text. 

Illustrations.  Graphs,  line  drawings,  photographs,  and  radiographs 
are  figures.  Use  only  illustrations  that  clarify  and  augment  the  text. 
Number  them  consecutively  as  Fig.  1 ,  Fig.  2,  and  so  forth  accord- 
ing to  the  order  by  which  they  are  mentioned  in  the  text.  Be  sure 
all  figures  are  cited.  If  any  figure  was  previously  published,  include 
copyright  holder's  written  permission  to  reproduce.  Figures  for 
publication  must  be  of  professional  quality.  Data  for  the  original 
graphs  should  be  available  to  the  Editor  upon  request.  If  color  is  essen- 
tial, consult  the  Editor  for  more  information.  In  reports  of  animal 
experiments,  use  schematic  drawings,  not  photographs.  A  letter  of 
consent  must  accompany  any  photograph  of  a  person.  Do  not  place 
titles  and  detailed  explanations  on  figures;  put  this  information  in 
figure  captions.  If  possible,  submit  radiographs  as  prints  and  full- 
size  copies  of  film. 

Drugs.  Identify  precisely  all  drugs  and  chemicals  used,  giving  gener- 
ic names,  doses,  and  routes  of  administration.  If  desired,  brand  names 
may  be  given  in  parentheses  after  generic  names.  Drugs  should  be 
listed  on  the  product-sources  page. 

Commercial  Products.  In  parentheses  in  the  text,  identify  any  com- 
mercial product  (including  model  number  if  applicable)  the  first  time 
it  is  mentioned,  giving  the  manufacturer's  name,  city,  and  state  or 
country.  If  four  or  more  products  are  mentioned,  do  not  list  any  man- 
ufacturers in  the  text;  instead,  list  them  on  a  Product  Sources  page 
at  the  end  of  the  text,  before  the  References.  Provide  model  num- 
bers when  available  and  manufacturer's  suggested  price,  if  the  study 
has  cost  implications. 

Ethics.  When  reporting  experiments  on  human  subjects,  indicate 
that  procedures  were  conducted  in  accordance  with  the  ethical  stan- 
dards of  the  World  Medical  Association  Declaration  of  Helsinki 
[Respir  Care  1997;42(6):635-636]  or  of  the  institution's  committee 


RESPIRATORY  CARE  Manuscript  Preparation  Guide,  Revised  2/98 


Manuscript  preparation  Guide 


on  human  experimentation.  State  that  informed  consent  was 
obtained.  Do  not  use  patient's  names,  initials,  or  hospital  numbers 
in  text  or  illustrations.  When  reporting  experiments  on  animals,  indi- 
cate that  the  institution's  policy,  a  national  guideline,  or  a  law  on 
the  care  and  use  of  laboratory  animals  was  followed. 

Statistics.  Identify  the  statistical  tests  used  in  analyzing  the  data, 
and  give  the  prospectively  determined  level  of  significance  in  the 
Methods  section.  Report  actual  p  values  in  Results.  Cite  only  text- 
book and  published  article  references  to  support  choices  of  tests.  Iden- 
tify any  general-use  or  commercial  computer  programs  used,  nam- 
ing manufacturers  and  their  locations.  These  should  be  listed  on  the 
product-sources  page. 

Units  of  Measurement.  Express  measurements  of  length,  height, 
weight,  and  volume  in  metric  units  appropriately  abbreviated;  tem- 
peratures in  degrees  Celsius;  and  blood  pressures  in  millimeters  of 
mercury  (mm  Hg).  Report  hematologic  and  clinical-chemistry  mea- 
surements in  conventional  metric  and  in  SI  {Systeme  Internationale) 
units.  Show  gas  pressures  (including  blood  gas  tensions)  in  torr. 
List  SI  equivalent  values,  when  possible,  in  brackets  following  non- 
Si  values— for  example,  "PEEP,  10  cm  H2O  [0.981  kPa)."  For  con- 
version to  SI,  see  RESPIRATORY  Care  1988;33(  I0):861-873  (Oct 
1988),  l989;34(2);l45(Feb  1989),  and  l997;42(6):639-640(June 
1997). 

Conflict  of  Interest  Authors  are  asked  to  disclose  any  liaison  or  finan- 
cial arrangement  they  have  with  a  manufacturer  or  distributor  whose 
product  is  part  of  the  submitted  manuscript  or  with  the  manufacturer 
or  distributor  of  a  competing  product.  (Such  arrangements  do  not 
disqualify  a  paper  from  consideration  and  are  not  disclosed  to  review- 
ers.) A  statement  to  this  effect  is  included  on  the  cover-letter  page. 
(Reviewers  are  screened  for  possible  conflict  of  interest.) 

Abbreviations  and  Symbols.  Use  standard  abbreviations  and  sym- 
bols. Avoid  creating  new  abbreviations.  Avoid  all  abbreviations 
in  the  title  and  unusual  abbreviations  in  the  abstract.  Use  an  abbre- 
viation only  if  the  term  occurs  several  times  in  the  paper.  Write  out 
the  full  term  the  first  time  it  appears,  followed  by  the  abbreviation 
in  parentheses.  Thereafter,  employ  the  abbreviation  alone.  Never 
use  an  abbreviation  without  defining  it.  Standard  units  of  mea- 
surement can  be  abbreviated  without  explanation  (eg,  10  L/min, 
15  torr,  2.3  kPa). 

Please  use  the  following  forms;  cm  H2O  (not  cmH20),  f  (not  bpm), 
L  (not  1),  L/min  (not  LPM,  l/min,  or  Ipm),  mL  (not  ml),  mm  Hg  (not 
mmHg),  pH  (not  Ph  or  PH),  p  >  0.001  (not  p>O.OOI),  s  (not  sec), 
Sp02  (pulse-oximetry  saturation).  See  RESPIRATORY  CARE: 
Standard  Abbreviations  and  Symbols  [Respir  Care  1997;42(6):637- 
642]. 

Submitting  the  Manuscript 

Mail  three  copies  [1  copy  with  author(s)  name(s),  affiliation(s),  2 
copies  without  name(s)  and  affiliation(s)  for  reviewers]  of  the  manu- 
script, figures,  and  I  diskette,  and  the  Cover  Letter  &  Checklist  to 
RESPIRATORY  CARE,  600  Ninth  Avenue,  Suite  702,  Seattle  WA 
98 104.  Do  not  fax  manuscripts.  Protect  figures  with  cardboard.  Keep 
a  copy  of  the  manuscript  and  figures.  Receipt  of  your  manuscript 


will  be  acknowledged. 

Computer  Disl<ettes.  Authors  are  encouraged  to  submit  electron- 
ic versions  of  manuscripts  as  well  as  printed  copies  (3.5  in.  diskettes 
in  Macintosh  or  IBM-DOS  format).  Label  each  diskette  with  date; 
author's  name;  name  and  version  of  word-processing  program  used; 
and  filename(s).  Software  used  to  produce  graphics  and  tables  should 
be  similarly  identified.  Do  not  write  on  diskette  labels  except  with 
felt-tipped  pen.  If  revision  of  a  manuscript  is  required  as  a  condi- 
tion of  acceptance  for  publication,  we  ask  that  an  electronic  version 
of  revision  be  supplied  to  facilitate  copyediting  and  production. 

Prior  and  Duplicate  Publication.  Work  that  has  been  published 
or  accepted  elsewhere  should  not  be  submitted.  In  special  instances, 
the  Editor  may  consider  such  material,  provided  that  permission  to 
publish  is  given  by  the  author  and  original  publisher.  Please  con- 
sult the  Editor  before  submitting  such  work. 

Authorship.  All  persons  listed  as  authors  should  have  participat- 
ed in  the  reported  work  and  in  the  shaping  of  the  manuscript;  all  must 
have  proofread  the  submitted  manuscript;  and  all  should  be  able  to 
publicly  discuss  and  defend  the  paper's  content.  A  paper  with  cor- 
porate authorship  must  specify  the  key  persons  responsible  for  the 
article.  Authorship  is  not  justified  solely  on  the  basis  of  solicitation 
of  funding,  collection  or  analysis  of  data,  provision  of  advice,  or  sim- 
ilar services.  Persons  who  provide  such  ancillary  services  exclusively 
may  be  recognized  in  an  Acknowledgments  section. 

Permissions.  The  manuscript  must  be  accompanied  by  copies  of 
permissions  to  reproduce  previously  published  material  (figures  or 
tables);  to  use  illustrations  of  or  report  sensitive  personal  information 
about,  identifiable  persons;  and  to  name  persons  in  the  Acknowl- 
edgments section. 

Reviewers.  Please  supply  the  names,  credentials,  affiliations,  address- 
es, and  phone/fax  numbers  of  three  professionals  whom  you  con- 
sider expert  on  the  topic  of  your  paper.  Your  manuscript  may  be  sent 
to  one  or  more  of  them  for  blind  peer  review. 


Editorial  Office: 

RESPIRATORY  CARE 

600  Ninth  Avenue,  Suite  702 
Seattle  W A  98104 

(206)  223-0558  (voice) 

(206)  223-0563  (fax) 

e-mail:  rcjournal@aarc.org 

kreilkamp@aarc.org 


RESPIRATORY  CARE  Manuscript  Preparation  Guide,  Revised  2/98 


COVER  LETTER  &  CHECKLIST 

A  copy  of  this  completed  form  must  accompany  all  manuscripts  submitted  for  publication. 


Title  of  Paper: 


Publication  Category: 


Corresponding  Author: Phone: FAX:. 

Mailing  Address: 


Reprints:      □  Yes     □  No  E-mail  Address: 


"We,  the  undersigned,  have  all  participated  in  the  work  reported,  proofread  the  accompanying  manuscript,  and  approve  its  sub- 
mission for  publication."  Please  print  and  include  credentials,  title,  institution,  academic  appointments,  city  and  state.  If  more 
than  4  authors,  please  use  another  copy  of  this  form.* 

'First  Author: 


Author  Signature/Date. 


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Has  this  research  been  presented  in  any  public  forum?       □  Yes    □  No 
If  yes,  where,  when  and  by  whom? 


Has  this  research  received  any  awards?         □  Yes    □  No 
If  yes,  please  describe. 


Has  this  research  received  any  grants  or  other  support,  financial  or  material?      □  Yes    □  No 
If  yes,  please  describe. 


Do  any  of  the  authors  of  this  manuscript  have  a  financial  interest  in  (or  a  commercial  or  consulting  relationship  to)  any  of  the 
products  or  manufacturers  mentioned  in  this  paper  or  any  competing  products  or  manufacturers?        □  Yes    □  No 


If  yes,  please  describe. . 


□  Have  you  enclosed  a  copy  of  the  manuscript  on  diskette? 

□  Is  double-spacing  used  throughout  entire  manuscript? 

□  Are  all  pages  numbered  in  upper-right  corners? 

□  Are  all  references,  figures,  and  tables  cited  in  the  text? 

□  Has  the  accuracy  of  the  references  been  checked,  and  are  they  correctly  formatted? 

□  Have  SI  values  been  provided? 

□  Has  all  arithmetic  been  checked? 

□  Have  generic  names  of  drugs  been  provided? 

□  Have  necessary  written  permissions  been  provided? 

□  Have  authors'  names  been  omitted  from  text  and  figure  labels? 

□  Have  copies  of  'in  press'  references  been  provided? 

□  Has  the  manuscript  been  proofread  by  all  the  authors? 

□  Have  the  manufacturers  and  their  locations  been  provided  for  all  devices  and  equipment  used? 

Respiratory  Care  Manuscript  Preparation  Guide,  Revised  2/98 


Not-for-profit  organizations  are  offered  a  free  advertisement  of  up  to  eight  lines  to  appear,  on  a  space-available 

basis,  in  Calendar  of  Events  in  RESPIRATORY  CARE.  Ads  for  other  meetings  are  priced  at  $5.50  per  line  and  require 

an  insertion  order.  Deadline  is  the  20th  of  the  month  two  months  preceding  the  month  in  which  you  wish  the  ad  to  run. 

Submit  copy  and  insertion  orders  to  Calendar  of  Events,  RESPIRATORY  CARE.  1 1 030  Abies  Lane,  Dallas  TX  75229-4593. 


Calendar 
of  Events 


AARC  &  AFFILIATES 

July  16-18 — Phoenix,  Arizona 

The  Pointe  Hilton  Resort  at  Squaw 
Peak  is  the  site  of  the  1999  AARC 
Summer  Forum.  Topics  include  "The 
ABCs  of  Authoring  Test  Questions," 
"Outcomes:  What's  All  the  Fuss?" 
and  "Computer  Technology  —  New 
Paradigm  in  Education."  The  three- 
day  conference  is  approved  for  up  to 
1 8  hours  of  CRCE  credits. 
Contact:  The  national  AARC  office 
at  (972)  243-2272  or  register  online  at 
www.aarc.org. 

July  18-20 — Phoenix,  Arizona 
The  AARC  will  be  conducting  the 
Patient  Assessment  Course  for 
respiratory  therapists  at  The  Pointe 
Hilton  Resort  at  Squaw  Peak 
immediately  following  the  Summer 
Forum.  Each  attendee  will  receive  a 
pocket  guide  to  physical  assessment, 
and  1 6  hours  of  CRCE  credit  are 
available  as  well  as  a  certificate  of 
course  completion.  Preregistration  is 
required. 
Contact:  (972)  243-2272. 

August  25-27— Cleveland,  Ohio 
The  OSRC  state  conference  will  be 
held  at  the  Holiday  Inn  in 
Independence,  just  south  of 
Cleveland.  Specialty  sessions  include 
critical  care,  pediatrics,  rehab/ 
continuing  care,  research,  and 
management. 

Contact:  Joe  Huff  at  (216)  861-6200, 
ext.  3892,  ewlul8a@prodigy.com  or 
Nancy  Johnson  at  (330)  929-7 166, 
abbyru@aol.coni. 

September  16-17 — Pittsburgh, 

Pennsylvania 

The  PSRC  will  host  their  26th  Annual 
Western  Pennsylvania  Regional 
Pulmonary  Medicine  and  Physiology 
Conference  at  the  Sheraton  Station 
Square.  Topics  include  management, 
critical  care,  sleep  diagnostics, 
pulmonary  rehabilitation,  and  the 


physician  forum. 

Contact:  Debbie  Logan  at  (800)  545- 

4663,  ext.  112. 

September  24-25 — Cleveland,  Ohio 
The  AARC  presents  the  "Disease 
Management  of  Asthma"  seminar. 
Come  and  join  a  distinguished  faculty 
as  they  review  the  NIH  asthma 
guidelines,  marketing  the  asthma 
program,  pharmacology,  and 
numerous  other  aspects  of  asthma 
program  management. 
Contact:  The  AARC  Conventions 
Office  at  (972)  243-2272. 

October  1 — Melville,  New  York 
The  NYSSRC's  Southeastern  Chapter 
hosts  their  3 1  st  annual  symposium, 
"Respiratory  Care  —  A  Work  in 
Progress,"  at  the  Huntington  Hilton 
Hotel  in  Melville,  Long  Island.  The 
keynote  address  will  be  given  by  Carl 
Wiezalis,  vice-president  of  the  AARC. 
Contact:  For  information,  call  Jim 
Ganetisat(516)444-3181or 
www.nyssrc.org. 

October  20-22— Daniels,  West 

Virginia 

The  West  Virginia  Society  for 
Respiratory  Care  will  host  its  Annual 
Fall  Meeting  at  the  Glade  Springs 
Resort,  Country  Inns  and  Suites. 
Contact:  For  more  information, 
contact  Jay  Wildt,  co-chair  of 
program  and  education,  at 
(304)  442-7474. 

December  13-16 — Las  Vegas,  Nevada 
The  AARC's  45th  International 
Respiratory  Congress  is  scheduled  for 
Dec.  13-16  (Monday  through 
Thursday)  at  the  Las  Vegas 
Convention  Center.  Sessions 
appealing  to  all  levels  of  health  care 
providers  will  be  offered,  with  CRCE 
credit  available.  Exhibits  by 
international  manufacturers  of 
cardiopulmonary  equipment  will  be 
featured.  Additional  information  will 
be  available  in  the  fall. 


Other  Meetings 

August  19-20— Cleveland,  Ohio 
The  Cleveland  Clinic  Foundation  is 
sponsoring  a  continuing  education 
program  titled  "Respiratory  Therapy," 
which  has  been  approved  for  Category 
I  accreditation.  It  will  be  held  at  the 
Omni  International  Hotel. 
Contact:  For  more  information,  call 
Laurie  Martel  at  (216)  444-5696  or 
(800)862-8173. 

October  1-3 — Ottawa,  Ontario, 

Canada 

The  Canadian  COPD  Alliance  will 
host  "Building  and  Enriching 
Partnerships  in  the  Management  of 
COPD"  at  the  Radisson  Hotel  Ottawa 
Centre.  This  conference  will  include 
plenary  sessions  on  the  epidemiology 
of  COPD  and  scientific  workshops  on 
spirometry,  smoking  cessation,  and  the 
evidence  to  support  management 
approaches  to  COPD.  Included  is  a 
series  of  practical  workshops  on 
rehabilitation  and  a  parallel  consumer 
track  for  those  who  live  with  COPD. 
Contact:  call  (613)  747-6776  or  see 
their  web  site  at  www.lung.ca/CCA/ 
conference. 

October  4-5 — Ann  Arbor,  Michigan 
The  Office  of  Continuing  Medical 
Education  at  the  University  of 
Michigan  is  sponsoring  a  conference, 
"Update  on  Pulmonary  and  Critical 
Care  Medicine,"  at  the  Towsley  Center. 
Contact:  For  more  information, 
contact  Laura  Castellanos  at 
(734)  647-8784. 

October  31-November  4 — Chicago, 

Illinois 

The  American  College  of  Chest 
Physicians  will  host  their  65th  Annual 
International  Scientific  Assembly  at 
the  Lakeside  Center.  For  information, 
contact  Member  Services  at  (800) 
343-2227,  fax  (847)  498-5460,  or 
www.chestnet.org. 


RESPIRATORY  CARE  •  JUNE  1999  VOL  44  NO  6 


717 


Notices 


Notices  of  competitions,  scholarships,  fellowships,  examination  dates,  new  educational  programs, 

and  the  like  will  be  listed  here  free  of  charge.  Items  tor  the  Notices  section  must  reach  the  Journal  60  days 

before  the  desired  month  of  publication  (January  I  tor  the  March  issue,  February  I  for  the  April  issue,  etc).  Include  all 

pertinent  information  and  mail  notices  to  RhSFIRA lORY  CARE  Notices  Dept,  1 1030  Abies  Lane,  Dallas  TX  75229-4593. 


eaao 


il  Helpful  LiJeb|Sites 

American  Association  for  Respiratory  Care 

http://www.aarc.org 

—  Current  job  listings 

—  American  Respiratory  Care  Foundation 
fellowships,  grants,  &  awards 

—  Clinical  Practice  Guidelines 

Nationai  Board  for  Respiratory  Care 

http.7/www. nbrc.org 

RESPIRATORY  CARE  online 

http://www.rcjournal.com 

—  1 997  Subject  and  Author  Indexes     ^ 

—  Contact  the  editorial  staff 

Asthma  Management 
iModei  System 

http://www.nhlbi.nih.gov  : 


The  National  Board  for  Respiratory  Care — 1999  Examination  Dates  and  Fees 


Examination 

CRTT  (CRT)  Examination 

RRT  Examination 


Examination  Date 

Novetnber  13,  1999 

Application  Deadline:  September  1,  1999 

December  4,  1999 

Application  Deadlitie:  August  1,  1999 


Examination  Fee 

$120  (new  applicant) 

80  (reapplicant) 

120  written  only  (new  applicant) 

80  written  only  (reapplicant) 

1 30  CSE  only  (all  applicants) 

250  Both  (new  applicants) 

2 1 0  Both  (reapplicants) 


For  information  about  other  services  or  tees,  write  to  the  National  Board  for  Respiratory  Care, 
8310  Nieman  Road,  Lenexa  KS  66214,  or  call  (913)  .^99-4200,  hAX  (913)  54  l-0156,or  e-mail:  nbrc-infoca nbrc.org 


718 


RESPIRATORY  CARE  •  JUNE  1999  VOL  44  NO  6 


NOTICES 


WATCH     FOR 
SPECIAL    ISSUE 
PART 

ARTIFICIAL 
AIRWAYS 

JULY    19  9  9 

(^ummet 


arum 


oenix 


New  Additions  to  AARC  Web  Site  Make 
Communication  Easy 

The  AARC's  web  site  (www.aarc.org)  make  communication 
with  the  AARC  Executive  Office  and  among  other  AARC  mem- 
bers much  more  direct  and  accessible.  Recent  additions  to  the 
site  include: 

Chat  —  AARC  members  can  chat  in  real  time.  Organized  chats 
on  specific  topics  will  be  planned  in  the  future. 
Just  Ask  —  Do  you  have  a  question  about  AARC  policies  or 
positions  on  issues?  Do  you  need  help  in  interpreting  reim- 
bursement and  government  policies?  Do  you  want  to  know 
what  the  AARC  is  doing  about  legislative  advocacy?  You  can 
post  a  question  in  this  area  for  possible  posting. 
Hotline  to  the  President  —  Do  you  want  immediate  action 
from  the  top?  Click  on  the  "red  phone"  hotline  to  President 
Dianne  Kimball.  An  E-mail  will  be  sent  directly  to  her. 
Help  Line  —  Do  you  have  a  clinical  or  professional  question 
you  want  answered?  Post  it  on  the  help  line  and  other  AARC 
members  will  respond. 

Specialty  Section  Mailing  Lists  —  If  you  are  a  member  of  one 
of  the  nine  specialty  sections,  you  have  instant  networking 
capabilities  through  the  electronic  mailing  lists  of  each  group. 

Patient  Assessment  Course  for  Respiratoiy  merapists 

Due  to  overwhelming  demand,  the  patient  assessment  course  for 
respiratory  therapists  is  being  offered  twice  this  year.  The  first  test 
date  has  passed,  and  the  remaining  test  will  be  conducted  in 
Phoenix,  Arizona  from  July  18-20  (immediately  following  Summer 
Forum).  Space  is  at  a  premium  and  preregistration  is  required. 
Successful  completion  of  the  course  will  earn  participants  16 
hours  of  CRCE  credit  and  a  certificate  of  course  completion.  Each 
attendee  will  be  given  a  pocket  guide  to  physical  assessment,  to 
help  them  on  the  job.  Following  the  last  class,  participants  will 
take  a  100-item  test  developed  by  the  NBRC.  Tests  will  be  graded 
on-site  for  those  wishing  to  obtain  their  scores  immediately.  For 
more  information  and  to  register,  visit  the  AARC  web  site  at 
www.aarc.org. 

AARC,  Affiliates  Set  Conference  Sciiedules 

The  AARC  and  many  of  the  affiliates  have  set  their  schedules 
for  1999  conferences  and  seminars.  Foremost  among  AARC's 
offerings  are  its  Summer  Forum  (July  16-18)  and  Annual 
International  Respiratory  Congress  (Dec.  13-16).  Check  out 
the  AARC's  website  at  www.aarc.org  for  all  meeting 
registration  materials  and  a  list  of  affiliate  conferences. 

Videoconference  Program  Set;  Nursing  CEUs 
Offered 

A  series  of  eight  videoconferences  are  scheduled  for  1999 
through  the  AARC  Professor's  Rounds  series,  which  are  now 
approved  for  nursing  CEUs  as  well  as  CRCE  credit.  Topics  are: 
respiratory  assessment,  asthma  management,  ventilator  man- 
agement, disease  management,  pediatric  emergencies,  COPD, 
PEEP,  and  respiratory  pharmacology. 

CRCE  Online  Debuts 

Now  you  can  earn  continuing  education  on  the  Internet  from 
the  AARC  through  its  new  CRCE  Online  website.  After  you  pay 
for  the  number  of  continuing  education  units  you  wish  to 
attempt  (by  submitting  your  credit  card  number  on  a  secure 
server  site),  you  are  given  access  to  the  list  of  courses.  Read 
the  material,  take  the  test,  and  then  print  out  a  certificate 
showing  you  passed.  Your  participation  will  also  be  noted  on 
your  CRCE  record  with  the  AARC.  Log  on  to  the  AARC's  web- 
site at  www.aarc.org  and  look  for  CRCE  Online. 


RESPIRATORY  CARE  •  JUPJE  1999  VOL  44  NO  6 


719 


Authors 
in  This  Issue 


Branson,  Richard  D 593,  630 

Chang,  Jacquehne 702 

Durbin,  Charles  G  Jr 593,  661 

Gladwin,  Mark  T 704 

Hess,  Dean  R 604 

Hurford,  William  E 615,  643 


Jaeger,  J  Michael 661 

Mageto,  Yolanda 704 

Ritz,  Ray 686 

Stoller,  James  K 595 

Susla,  Gregory  M 702 

Thompson,  Ann  E 650 


Advertisers 
in  This  Issue 


To  advertise  in  RESPIRATORY  CARE,  contact  Tim  Goldsbury,  20  Tradewinds  Circle,  Tequesta  FL  33469 
at  (561)  745-6793,  Fax  (561)  745-6795.  e-mail:  goldsbury@aarc.org,  for  rates  and  media  kits.  For  recruitmenty 
classified  advertising  contact  Beth  Binkley,  Marketing  Assistant  for  RESPIRATORY  CARE,  at  (972)  243-2272. 
Fax  (972)  484-6010.  Rick  Owen  is  the  Marketing  Director  for  RESPIRATORY  CARE. 


California  College  for  Health  Sciences 571 

Circle  Reader  Service  No.  106  Call  (800)  961-6409 

Cardiopulmonary  Corp 575 

Circle  Reader  Service  No.  108  Call  (800)  337-9936 

DEY  Laboratories Cover  2 

Circle  Reader  Service  No.  1 33  Call  (800)  527-4278 

DHD  Healthcare Cover  4 

Circle  Reader  Service  No.  110  Call  (800)  847-8000 

Kaiser  Permanente 577 

Circle  Reader  Service  No.  115  Call  (800)  33 1-3976 

Maxtec  Inc 581 

Circle  Reader  Service  No.  1 1 7  Call  (800)  748-5355 


Marcel  Dekker  Inc 706 

Circle  Reader  Service  No.  102  Call  (212)  696-9000 

Pulmonetic  Systems  Inc Cover  3 

Circle  Reader  Service  No.  1 29  Call  (800)  754- 1914 

Respironics  Inc 569 

Circle  Reader  Service  No.  125  Call  (800)  669-9234 

Siemens  Medical  Systems 562 

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Westmed  Inc 566 

Circle  Reader  Service  No.  104  Call  (800)  724-2328 


Copyright  Information.  Respiratory  Care  is  copyrighted  by 
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written  permission  of  Daedalus  Enterprises  Inc  is  prohibited.  Permission  to 
photocopy  a  single  article  in  this  Journal  for  noncommercial  purposes  of 
scientific  or  educational  advancement  is  granted.  Permission  for  multiple 
photocopies  and  copies  for  commercial  purposes  must  be  requested  in  writ- 
ing, via  e-mail  (rcjoumaKgiaarc.org),  or  telephone  and  approved  by  RESPI- 
RATORY Care.  Anyone  may,  without  permission,  quote  up  to  500  words  of 
material  in  this  journal  provided  the  quotation  is  for  noncommercial  use  and 
RESPIRATORY  CARE  is  credited.  Longer  quotation  requires  written  ap- 
proval by  the  author  and  publisher.  Single  reprints  are  available  only  from  the 
authors.  Reprints  for  commercial  use  may  be  purchased  from  Daedalus  En- 
terprises Inc.  For  more  information  and  prices  call  (972)  243-2272. 

Disclaimer.  The  opinions  expressed  in  any  article  or  editorial  are  those 
of  the  author  and  do  not  necessarily  reflect  the  views  of  the  Editors,  the 
American  Association  for  Respiratory  Care  (AARC),  or  Daedalus  Enter- 
prises Inc.  Neither  are  the  Editors,  the  AARC,  or  the  Publisher  responsible 
for  the  consequences  of  the  clinical  applications  or  use  of  any  methods  or  de- 
vices described  in  any  article  or  advertisement. 

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Copyright  ©  1999,  by  Daedalus  Enterprises  Inc. 


720 


RESPIRATORY  CARE  •  JUNE  1999  VOL  44  NO  6 


Small  Enough  for  Homecare.., 

Powerful  Enough  for  Acute  Care 


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'#♦»' 


I    TYPEOf  INSTTTUnON 
ORPHACnCE 


117  118 

135  136 

U3  U4 

171  172 

189  190 


n  Hospital 

n  Skilled  Nursing 

Facility 

G  Subacute  Care  Facility 

n  Home  Care  Practice 

D  School 

D  Distributor 


II   DEPARTMENT 

A  D  Respiratory  Care 
B   D  Cardiopulmonary 
C  n  Subacute  Care 
D  n  Home  Care 

HISPEOALTY 

1  D  Clinician 

2  D  PerinaUl/  Pediatrics 

3  D  Critical  Care 

4  D  Research 

5  D  Subacute  Care 


6  D  Diagnostics/ 

Pulmonary  Function 

7  n  Management 

8  D  Home  Care 

9  D  Rehabilitation 

10  D  Education 

IV  POSITION 

A  D  Department  Head 

B  n  Chief  Therapist 

C  D  Supervisor 

D  D  Staff  Therapist/ 

Technician 

E  D  Medical  Director 

F  D  Educator/Instructor 

C  n  Sales 

H  D  Other  (please  specify) 


V  AREYOUANAARC 
MEMBER? 

1    D  Yes    2    D   No 


iul  Functions 

■e  or  Volume  Control 
'e  Support 

'iggering 

e  Breath  Termination  Criteria 

I  Supplementation 

ble  Configuration 

)  X  3  incties 
3ight-only  12.6  lbs. 
I  Battery 
essorless  Technology 


msssis 


100Q       Cw« 


PF/PIPATnDU  rADE 


Authors 
in  This  Issue 


Branson,  Richard  D . 
Chang,  Jacqueline  .  .  . 
Durbin,  Charles  G  Jr  , 
Gladwin,  Mark  T.  .  .  . 

Hess,  Dean  R 

Hurford,  William  E  .  , 


.  593,  630  Jaeger,  J  Michael 661 

....  702  Mageto,  Yolanda 704 

.  593,  661  Ritz,  Ray 686 

704  Stoller,  James  K 595 

604  Susla,  Gregory  M 702 

,615,  643  Thompson,  Ann  E 650 


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Copyright  Inforiv 

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