(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Biodiversity Heritage Library | Children's Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "Respiratory care : the official journal of the American Association for Respiratory Therapy"

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 
*\OF ASTECH INSTRUMENTS - 
Pi^^ FOR YEARS. ' 




|ust as ancient institutions relied on the Aztec 
calendar for vital measurements of time, today's 
leading medical institutions rely on ASTECH Peak 
Flow Meters for vital patient measurements* 
Because more accurate information leads to more 
effective therapy. 

Entrust the health of your patients to the peak 
flow meter trusted by some of the leading medical 
hospitals for pulmonary medicine. 

The ASTECH Peak Flow Meter. A precision instru- 
ment with a record of accuracy and reproducibility 
that has stood the test of time in the most 
demanding environments. 

Call 800-527-4278 today for really accurate infor- 
mation about a really accurate peak flow meter. 



*/4 



ZENITH A«- 



ASTECH' PEAK FLOW METER 



®l999DEy. All rights reserved. 
09-733-00 1/99 

' National Jewish Medical and Research Center (ratiked #1 tot pulmonary diseases b\' U.S. News and Wbrid Report, 
ttily 1 998} &r)6 other ttiought leaders L'se the Astech Pealt Flow Meter exclusively. 

Circle 133 on reader service card 



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 

$65 for AARC members, $90 for nonmembers-ltem BK55 

Cadd $8 for shipping and handling] 

Texas customers only, please add 8.25% sales tax Oncluding shipping charges). Texas customers that are exempt from 
sales tax must supply an exemption certificate. MasterCard, Visa, Institutional Purchase Order, or check payable to: 

Daedalus Enterprises, Inc. 

ATTN: Order Fulfillment Department 
1 1030 Abies Lane / Dallas, Texas 75229 / Phone (972} 243-2272 / Fax (972) 484-6010 / www.aarc.org 



SIEMENS 




< 



The greatest savings we offer youT 
:- benefit him first. 



The less time he has to spend on a ventilator, the more 
he benefits. When you invest in Servo Ventilator 300A 
technology, everybody benefits. Enroll in Siemens 
Clinical Management Program™ and we guarantee a 
minimum 5% reduction in ventilator length of stay, 
together with associated cost savings. The Servo 300A 
provides the lowest cost per procedure compared to 



competitive devices. With proven 99.9% uptime, you 
can maximize clinical outcomes while lowering the 
cost of care. And right now, when you purchase your 
Servo 300A, you have the option of paying nothing until 
the year 2000. Interest free. Interested? For more 
information, contact your local Siemens representative 
or call 1-800-333-8646. 



Servo 300A 


wm 


■H 


m 


"# 


Ventilation 
System 










4 


: ^ 


. i, f 


,JL 


^ 



Siemens medical 

Solutions that help 



Circle 112 on reader service card 



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 F IBROSIS. 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.) 



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. 



Order by calling (800) 434-4034 

' Guaranteed refund on all unopened products returned within 90 days of purcha; 



VORTRAN Medical Technology 1, Inc. 

3941 J Street, Suite 354 TEL: (800)434-4034 

Sacramento, C A 95819-3633 FAX: (916)454-0490 
htlp:\\www.vortran.com E-mail: offlce@vortran.ci 



Circle 127 on reader service card 



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. 

Circle 104 on reader service card 

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 





J 




•+ — ^ 



**^ i 



C*^ji 



?/ 




• '-'h ', :■■■": .''yjS^jt'-Si/jifef. -I 



Let Our Vision'" Of Tiie 
Present Help You Realize 
Your Vision Of Tiie Future. ^ 



Introducing The BiPAP®Vision™System. 
The Future Of Noninvasive Ventilatory Care. 

Higher Performance Capabilities provide 
you with higher flow and a wider pressure 
range to meet the challenging needs of 
patients with high breathing demand. 

Auto-Trak Sensitivity™ ensures an 
automatic breath-by-breath response to 
the patient's breathing patterns and circuit 
leaks, providing optimum support with 
every breath. 

To see a Vision for yourself or for more 
Information, call 1-800-345-6443. Rnd 
__ , out how the Vision System advances 
reliable O2 administration (from —cssrs respiratory care. 
21-100%) despite mask leaks. 



Designed with the user and the patient in 
mind, the BIPAP Vision System will help 
improve the way you treat your patients 
who require noninvasive ventilation. So 
versatile and simple. It's a dream come 
true for hospital and alternate care 
providers. 

Integrated Display Screen with real-time 
graphics, patient and system data, and 
alarm options provides complete 
patient monitoring. 

Adjustable Oxygen Control allows J^ti 

^^1 




Warning: The BiW '^'^'^"^Jf;^"'^f'^^;^l^l^°' '"t^ to augment Je ventilation of a spontaneously breathing patient. Refer to the BiW Vision System clinical manual 

for complete information on applications. Caution: U.S. federal la* restncts this device to sale by or on the order of a physician 

BiPAP. Vision and Auto-Trak Sensitivity are trademarks of Respironics. Inc. 

Circle 125 on reader service card 




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 



Advance Your Healthcare Career! 



Complete Your Degree at Home! 

Achieve Success Through Distance Education! 

Karn the educational credentials you need to advance your career — without 
spending extra time and money attending an on-campus university. Choose from 
California College for Health Sciences' exciting line-up of Associate, Bachelor's and 
Master's Degree Programs. 'Ybu'll enjoy the benefits that come with respeaed 
credentials in any one of 34 fast-growing healthcare or business specialties. 

• Accredited Member, Distance Education and Training Council. 

• You may be able to receive credit for previous college courses or work 
experience equivalent to college or university learning. 



CAU OR SEND FOR 
FREE INFORMATION! 

1-800-961-6409 

www.cchs.edu 

No obligation. Act today! 




Call today or send 
this coupon to: 



CCHS 



Since 1978 

California College 
for Health Sciences 

Dept. 1861 

222 West 24th St. 

National City, CA 91950 

FAX: (619) 477-4360 

cchsinfo@cchs.edu 



1 want to find out more about continuing my professional education at home with California College for Health 
Sciences No obligation Act today! Choose ONE ofthefoUoiving accredited programs: 



School of Health Sciences 

Master of Science in 
Healtli Services 

concentrations in: 



Associate of Science 

n Respiratory 
Technician 
n Respiratory Therapist 
D Allied Health 
n EEC Technologist 
Bachelor of Science 
in Health Services 
majors in: 
n Management 
D Respiratory Care 



School of Business 

Associate of Bachelor of 



D Community Health 
n Wellness Promotion 

Certificate Programs 
for Colleee Credit 

n Gerontology 

D Community Health Education 

D Health Psychology 

D Healthcare Ethics 

n Polysomnography 

n Business Essentials 



Science in 
Business 

majors in: 

D Accounting 
n Finance 
n Management 
D Marketing 
n Economics 
n Business 



Science in 
Business 

majors in: 

D Accounting 
D Finance 
n Management 
n Marketing 
n Economics 
D Business 



Career Diploma 
Programs 

D Pharmacy Technology 
D Dental Assisting 
D Medical Assisting 
D EKG Technology 
n Home Health Aide 
D Physical Therapy Aide 



D Master in Public Health 

D Master of Science in Healthcare Administration 



Name 

Address 

City/State _ 
Phone ( 
Hospital/Facility _ 



)_ 



Apt. * 

Zip_ 

E-mail . 



_Phone ( ) . 



California College for Health Sciences • A Division ofHarcourt Brace & Company 



Circle 106 on reader service card 



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 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 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- 



574 



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 





When was the last time 

your career made 

you feel this good? 



A prestigious consortium, the Pacific Business Group on Health, has 
honored us with Blue Ribbons for top quality clinical care, cost- 
effectiveness, automated data systems and the willingness to partner 
with business to improve employee health You too can share in the 
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 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 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 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 



■Respiratory Care • June 1999 Vol 43 No 6 



Maximize O2 Measurement with maxtec 



TM 





MSA Model* 

Respiratory Sensor 

MiniOX I. II, III 
MiniOX 3000 



maxtec ™ Inc. 




Air/Oxygen Mixer 

* Unmatched perfor- 
mance and reliability. 

* Simple operation. 

* Low cost. 



Siemens* 

Respiratory Sensor 

Models 900C & 300 
Ventilators 



FORMERLY CERAMATEC 



For more product information call: 800-748-5355 



2425 South 900 West, Suite B, S.L.C., Utah 84119 phone: 800-748-5355 fax: 801-956-1002 www.maxtednc.com 

MMSiMiiiMiSjSMiJmSAiMiii^ registered trademarks of their re.spective 



: Knot Mffiljated,nitli or endopivd b\ MSA or Siemens 



Circle 117 on reader service card 



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 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 



M\ to cut costs? 

Improve productivitij? 

Need help implementing protocols? 

Introducing the Universitj of California-San Diego 
Respiratory Care Patient Driven Protocols 

Developed by UCSD medical directors 
using AARC Clinical Practice Guidelines 

Provides 24 specific protocols in general and critical care including: 

'■' secretions management '•' oxygen '" chest percussion and drainage 

'"•■ extubation ''' aerosol therapy '■•'" volume reduction lung surgery 

management 

This manual defines: 

• how to document the initial ordering process 

• how to taper/discontinue treatments 

• the indications and standards of care 

• how to apply those criteria 

Additional Benefits: 

• enhance continuity of care 

• minimize variation in care 
• realize cost containment 

• improve utilization 

Written with the bedside practitioner in mind, these protocols saved UCSD almost 3 million dollars over 4 years! 

Start saving todaiil Order luhile supplies last! 



Phonc-in Orders: 972-243-2272 (Ask for Item #PA801) 
Fax Orders: 972-484-2720 



Price: $85 AARC Member AARC Member #_ 
$95 Non AARC Member 




ssfi 



|{(>si)ii-nl(ii-v Ciii'i' 
I'jilU'iil lli'ivi'n I'nilCHOlJ 



■ UmversHy of Cahlomia San D>»go. 
Rvspirakxy Services 



mmoDuciKG 



Item 


Quantity 


Price 


PA801 








Sub Total 






Tax 






Shipping 


$10 




Tota 





(TX orders add 8.25%) 



Name _ 
Facility . 



Shipping Address 

City 

Phone 



State 



□ Visa □ Mastercard #_ 
Expiration Date 



UmVEHSIIV of CnLIFOflHIH 
SHN DIEGO 



Respiroiorij 

Core 

Potieni 

Driven 

Protocols 



AMERICAN ASSOCIATION 
FOR RESPIRATORY CARE 



Signature 



■MttMMiaHIWlftlifi illifil''^ 




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, 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 



tember 
24-25 / 



Cleveland, Ohio 

4999 

sthma 

■ 

Disease State 
Management Course 



The course will provide up-to-date information and useful tools you can use on the job. The day and a half course providessi 
lectures covering: Disease Management, The NIH Asthma Gudelines, Education Strategies, Pharmacology, Marketing an 
Asthma Management Program, Outcomes Management, and Age Specific issues. Instruction begins at 12:30 Friday afternoon ■*" 
and concludes at 4:30 Saturday n • a m" w 

Reptration Form 

First and Last Name (include credentials) 



Ihis is the course you have been asking for! 
Drawing on the expertise of a nationally recognized 
faculty this course has been developed in accordance 
with the National Institute of Health Asthma Guide- 
lines for the Diagnosis and Management of Asthma. 
Completing this course will earn respiratory therapists 
II hours of continuing education credit. 




n AARCM 

Course Fee after September 3 

n AARC Member $275 D Nonmember $350 




n_ Check enclosed 

tcard#nn 

Signature 



Charge my : D VISA D MasterCard 




If paying by credit card, you may fax your Registration Form to 972.484.2720 
Mail registration Form and check, payable to: AARC • 11030 Abies Lane • TX 75229-4593 • 




Hotel Reservations 



All Asthma Disease State Management Course sessions will be held at 

The Marriott Cleveland Airport Hotel 

Cleveland, OH 

Room Rates: $92 (plus 14.5% tax) single or double occupancy 

For room reservations, call The Marriott Hotel at 1-800-228-9290 

toll-free number today and identify yourself as an attendee at the AARC Meetings. 

Cut-off date for the AARC's special room rates is August 30, 1999. 




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. 



596 



Respiratory Care • June 1999 Vol 44 No 6 



The History of Intubation, Tracheotomy, and Airway Appliances 



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- 



Respiratory Care • June 1999 Vol 44 No 6 



597 



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 



Respiratory Care • June 1999 Vol 44 No 6 



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 



Respiratory Care • June 1999 Vol 44 No 6 



599 



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 



Respiratory Care • June 1 999 Vol 44 No 6 



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. 



Respiratory Care • June 1999 Vol 44 No 6 



601 



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 



602 



Respiratory Care • June 1999 Vol 44 No 6 



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 / / 
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. 

REFERENCES 

1. AARC Clinical Practice Guideline. Management of airway emer- 
gencies. RespirCare 199.5;40(7):749-760. 

2. Bishop MJ. Airway Management. In: Tobin MJ. editor. Principles 
and practice of mechanical ventilation. New York: McGraw-Hill; 
1994. 

3. Plummer AL, Gracey DR. Consensus conference on artificial air- 
ways in patients receiving mechanical ventilation. Chest 1989;96(l): 
178-180. 

4. Reed AP. Current concepts in airway management for cardiopulmo- 
nary resuscitation. Mayo Clin Proc I995;70(I2):1 172-1 184. 

5. Mclntyre JWR. Oropharyngeal and nasopharyngeal airways. Can J 
Anaesth 1996;43(6):629-635. 



Respiratory Care • June 1999 Vol 44 No 6 



607 



Indications for Translaryngeal Intubation 



6. Greenberg RS. Brimacombe J, Berry A. et al. A randomized con- 
trolled trial comparing the cuffed oropharyngeal airway and the la- 
ryngeal mask airway in spontaneously breathing anesthetized adults. 
Anesthesiology l998;88(4):97()-977. 

7. Atherton GL, Johnson JC. Ability of paramedics to use the Combi- 
tube in prehospital cardiac arrest. Ann Emerg Med I99.'?;22(8): 1263- 
1268. 

8. Staudinger T. Tesinsky P, Klappacher G. Brugger S, Rintenlen C. 
Locker G, et al. Emergency intubation with the Combitubc in two 
cases of difficult airway management. Eur J Anaesthesiol 199,5; 
I2(2):I89-I93. 

9. Alexander R. Hodgson P, Lomax D, Bullen C. A comparison of the 
laryngeal mask airway and Guedel airway, bag and facemask for 
manual ventilation following formal training. Anaesthesia I993;48(3): 
231-234. 

10. The use of the laryngeal mask airway by nurses during cardiopul- 
monary resuscitation. Results ofa multicentre trial. Anaesthesia 1994; 
49(l):3-7. 

1 1 . Arosio EM. Conci F. Use of the laryngeal mask airway for respira- 
tory distress in the intensive care unit. Anaesthesia I995;50(7):635- 
636. 

1 2. Asai T, Morris S. The laryngeal mask airway: its features, effects and 
role. Can J Anaesth l994.4l(IO):93()-96(). 

13. Bailey AR. Hett DA. The laryngeal mask airway in resuscitation. 
Resuscitation 1994:28(2): 107-1 10. 

14. Benumof JL. Laiyngeal mask airway and the ASA difficult airway 
algorithm (review). Anesthesiology l996;84(3):686-699. 

15. Bogetz MS. The laryngeal mask airway-role in managing the diffi- 
cult airway. Int Anesthesiol Clin 1994:32(4): 109-1 17. 

16. Devitt JH. Wenslone R, Noel AG, O'Donnell MP. The laryngeal 
mask airway and positive-pressure ventilation. Anesthesiology 1994: 
80(3):550-555. 

17. Reinhart DJ, Simmons G. Comparison of placement of the laryngeal 
mask airway with endotracheal tube by paramedics and respiratory 
therapists. Ann Emerg Med 1994:24(2):260-263. 

18. Samarkandi AH. Seraj MA, el Dawlatly A, Mastan M. Bakhamees 
HB. The role of laryngeal mask airway in cardiopulmonary resusci- 
tation. Resuscitation 1994:28(2): 103-106. 

19. Sasada MP, Gabbott DA. The role of the laryngeal mask airway in 
pre-hospital care. Resuscitation 1994:28(2):97-I02. 

20. Weiler N, Latorre F, Eberle B, Goedecke R, Heinrichs W. Respira- 
tory mechanics, gastric insufflation pressure, and air leakage of the 
laryngeal mask airway. Anesth Analg 1997:84(.'i): 1025-1028. 

21. Brimacombe JR, Berry A. The incidence of aspiration associated 
with the laryngeal mask airway: a meta-analysis of published liter- 
ature. J Clin Anesth l995:7(4):297-305. 

22. Kil HK. Bishop MJ. Head position and oral vs nasal route as factors 
determining endotracheal tube resistance. Chest I994:l()5(6):1794- 
1797. 

23. Guttmann J, Eberhard L, Fabry B. Bertschmann W, Wolff G. Con- 
tinuous calculation of intratracheal pressure in tracheally intubated 
patients. Anesthesiology I993:79(3):503-513. 

24. Gal TJ. Pulmonary mechanics in normal .subjects following endo- 
tracheal intubation. Anesthesiology 1980:52( l):27-35. 

25. Bolder PM, Healcy TE, Bolder AR, Beatty PC, Kay B. The extra 
work of breathing through adult endotracheal tubes. Anesth Analg 
1986:65(8):85.3-859. 

26. Conti G. De Blasi RA, Lappa A, Ferretti A, Antonelli M. Bufi M, 
Gasparetto A. Evaluation of respiratory system resistance in mechan- 
ically ventilated patients: the role of the endotracheal tube. Intensive 
Care .Med l994:20(6):42l-424. 

27. Heyei- L. Louis B, Isabey D, Lofaso F, Broehard L, Fredburg JJ, Harf 
A. Noninvasive estimate of work of breathing due to the endotra- 
cheal tube. Anesthesiology 1996:85(6): 1324-1333. 



28. Lofaso F, Louis B, Broehard L, Harf A, Isabey D. Use of the Blasius 
resistance formula to estimate the effective diameter of endotracheal 
tubes. Am Rev Respir Dis l992:l46(4):974-979. 

29. Sullivan M, Paliotta J, Saklad M. Endotracheal tube as a factor in 
measurement of respiratory mechanics. J Appl Physiol 1976:41(4): 
590-592. 

30. Tipping TR, Sykes MK. Tracheal tube resistance and airway and 
alveolar pressures during mechanical ventilation in the neonate. An- 
aesthesia 1991 ;46(7):565-569. 

31. Shapiro M, Wilson RK, Casar G, Bloom K, Teague RB. Work of 
breathing through different sized endotracheal tubes. Crit Care Med 
1986; 1 4(1 2): 1 028- 1031. 

32. Yung MW, Snowdon SL. Respiratory resistance of tracheostomy 
tubes. Arch Otolaryngol 1984:1 10(9):591-595. 

33. van Surell C. Louis B, Lofaso F. Beydon L. Broehard L, Harf A, et 
al. Acoustic method to estimate the longitudinal area profile of en- 
dotracheal tubes. Am J Respir Crit Care Med l994:l49(l):28-33. 

34. Wright PE. Marini JJ. Bernard GR. In vitro versus in vivo compar- 
ison of endotracheal tube airflow resistance. Am Rev Respir Dis 
I989:I40(1):10-16. 

35. Broehard L, Rua F, Lorino H, Lemarie F, Harf A. Inspiratory pres- 
sure support compensates for the additional work of breathing caused 
by the endotracheal tube. Anesthesiology l99I:75(5):739-745. 

36. Fiastro JF, Habib MP, Quan SF. Pressure support compensation for 
inspiratory work due to endotracheal tubes and demand continuous 
positive airway pressure. Chest 1988;93(3):499-505. 

37. Kuhlen R. Rossaint R. Electronic extubation — is it worth trying it? 
(editorial). Intensive Care Med 1997:23(1 l):l 105-1 107. 

38. Guttmann J, Bernhard H, Mols G. Benzing A. Hofmann P. Haberthur 
C. et al. Respiratory comfort of automatic tube compensation and 
inspiratory pressure support in conscious humans. Intensive Care 
Med 1997:23(11):! 1 19-1 124. 

39. Fabry B, Haberthur C. Zappe D, Guttmann J, Kuhlen R, Stocker R. 
Breathing pattern and additional work of breathing in spontaneously 
breathing patients with different ventilatory demands during inspira- 
tory pressure support and automatic tube compensation. Intensive 
Care Med 1997;23(5):545-552. 

40. Esteban A, Alia 1, Gordo F, Fernandez R, Solsona JF, Vallverdu 1, et 
al. Extubation outcome after spontaneous breathing trials with T- 
tube or pressure .support ventilation. The Spanish Lung Failure Col- 
laborative Group. Am J Respir Crit Care Med 1997; 156(2 Pt l):459- 
465. Published erratum appears in Am J Respir Crit Care Med 
I997:I56(6):202H. 

41. Straus C, Louis B, Isabey D, Lemairc F, Harf A. Broehard L. Con- 
tribution of the endotracheal tube and the upper airway to breathing 
workload. Ain J Respir Crit Care Med l998:l57(l):23-30. 

42. Mehta S. The risk of aspiration in presence of cuffed endotracheal 
tubes. Br J Anaesth 1972;44(6):60l-605. 

43. Kollef MH, Silver P. Ventilator-associated pneumonia: an update for 
clinicians. Respir Care 1995;40( I l):l 1.30-1 140. 

44. McCleave DJ, Fisher M. Efficacy of high volume low pressure cuffs 
in preventing aspiration. Anesth Intensive Care 1977:5(2): 167-168. 

45. Macrae W, Wallace P. Aspiration around high-volume, low-pressure 
endotracheal cuff. Br Med J 198 1:283(630 1): 1 220. 

46. Seegobin RD. van Hasselt GL. Aspiration beyond endotracheal cuffs. 
Can Anaesth Soc J 1986:33(3 Pt l):27.3-279. 

47. Petring OU. Adelhoj B, Jensen BN, Pedersen NO, Lomholt N. Pre- 
vention of silent aspiration due to leaks around cuffs of endotracheal 
tubes. Anesth Analg 1986:65(7):777-780. 

48. Bernhard WN, Cottrell JE, Sivakumaran C, Patel K, Yost L, Turn- 
dorf H. Adjustment of intracuff pressure to prevent aspiration. An- 
esthesiology l979;50(4):363-366. 



608 



Respiratory Care • June 1999 Vol 44 No 6 



Indications for Translaryngeal Intubation 



49. Pavlin EG, Van Nimwegan D. Hornhein TF. Failure of a high- 
compliance low-pressure culT to prevent aspiration. Anesthesiology 
1975;42(2):2I6-219. 

50. Rello J, Sonera R, Jubert P. Artigas A. Rue M, Valles J. Pneumonia 
in intubated patients: role of respiratory airway care. Am J Respir 
Crit Care Med 1996;I54{1 ): 1 1 1-1 IS. 

51. Mahul P, Auboyer C. Jospe R. Ros A. Guerin C, el Khouri Z. el al. 
Prevention of nosocomial pneumonia in intubated patients: 
respective role of mechanical ventilation subglottic secretions drain- 
age and stress ulcer prophylaxis. Intensive Care Med I992;I8(I): 
20-25. 

52. Valles J. Artigas A. Rello J. Bonsoms N. Fontanals O, Blanch L. et 
al. Continuous aspiration of subglottic secretions in preventing ven- 
tilator-associated pneumonia. Ann Intern Med 1 995; 122(3): 1 79- 1 86. 

53. Sottile FD, Marrie TJ, Prough DS. Hobgood CD. Gower DJ. Webb 
LX, et al. Nosocomial pulmonary infection: possible etiologic sig- 
nificance of bacterial adhesion to endotracheal tubes. Crit Care Med 
1986;14(4):265-270. 

54. Inglis TJ, Millar MR, Jones JG. Robinson DA. Tracheal lube biofilm 
as a source of bacterial colonization of the lung. J Clin Microbiol 
1989;27(9):2014-2018. 

55. Bowinan FP, Menegazzi JJ, Check BD, Duckett TM. Lower esoph- 
ageal sphincter pressure during prolonged cardiac arrest and resus- 
citation. Ann Emerg Med 1995;26(2):216-219. 

56. Ruben H. Knudsen EJ, Carugati G. Gastric insufflation in relation to 
airway pressure. Acta Anaesth Scand 1961:5:107-1 14. 

57. Consensus statement: noninvasive positive pressure ventilation. Re- 
spir Care l997;42(4):365-369. 

58. Pang D, Keenan SP, Cook DJ, Sibbald WJ. The effect of positive 
pressure airway support on mortality and the need for intubation in 
cardiogenic pulmonary edema: a systematic review. Chest 1998; 
114(4):1 18.5-1 192. 



59. Keenan SP, Kennerman PD, Cook DJ, Martin CM, McCormack D. 
Sibbald WJ. Effect of noninvasive positive pressure ventilation on 
mortality in patients admitted with acute respiratory failure: a meta- 
analysis. Crit Care Med 1997:25(10); 1685-1692. 

60. Keenan SP, Brake D. An evidence-based approach to noninvasive 
ventilation in acute respiratory failure. Crit Care Clin 1998:14(3): 
359-372. 

61. Hess D. Noninvasive positive pressure ventilation: predictors of suc- 
cess and failure for adult acute care applications. Respir Care 1997: 
42(4):424-t31. 

62. Hill NS. Complications of noninvasive positive pressure ventilation. 
Respir Care I997;42(4);432^142. 

63. AARC Clinical Practice Guideline. Postural drainage therapy. Respir 
Care 1991;.36(12):1418-I426. 

64. AARCClinical Practice Guideline. Directed cough. RespirCare 1993; 
38(5):49.5-499. 

65. AARC Clinical Practice Guideline. Nasotracheal suctioning. Respir 
Care 1992;37(8):898-901. 

66. AARC Clinical Practice Guideline. Fiberoptic bronchoscopy assist- 
ing. Respir Care 1993:38(1 1):1 17.3-1 178. 

67. AARC Clinical Practice Guideline. Use of positive airway pressure 
adjuncts to bronchial hygiene therapy. RespirCare 1 993;38(5):5 16-521. 

68. Bach JR. Mechanical insuftlation-exsufnation. Comparison of peak 
expiratory flows with manually assisted and unassi.sted coughing 
techniques. Chest 1993; 104(5); 1553- 1.562. 

69. Hardy KA, Anderson BD. Noninvasive clearance of airway secre- 
tions. Respir Care Clin N Am 1996;2(2);323-345. 

70. Branson RD. The nuts and bolts of increasing arterial oxygenation: 
devices and techniques. Respir Care 1993;38(6):686. Discussion: 
687-689. 

71. Foust GN. Potter WH. Wilons MD. Golden EB. Shortcomings of 
using two jet nebulizers in tandem with an aerosol face Jiiask for 
optimal oxygen therapy. Chest 1991:99(6): 1346-1351. 



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 



Respiratory Care • June 1 999 Vol 44 No 6 



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. 



614 



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- 



Respiratory Care • June 1999 Voi. 44 No 6 



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 



618 



Respiratory Care • June 1999 Vol 44 No 6 



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 



61') 



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 
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 . AsV jK^^ 

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- 



622 



Respiratory Care • June 1999 Vol 44 No 6 



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). 



Respiratory Care • June 1999 Vol 44 No 6 



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 



624 



Respiratory Care • June 1999 Vol 44 No 6 



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. 

REFERENCES 

1. Roberts JT. Clinical manageinent of the airway. Philadelphia: WB 
Saunders; 1994. 

2. Roberts JT, Pino R. Functional anatomy of the airway. In: Roberts J. 
editor. Clinical management of the airway. Philadelphia: WB Saun- 
ders; 1994:2-17. 

3. Alikhani S. Roberts JT. Airway evaluation and management. In: 
Hurford W. Bailin M. Davison J. Haspel K, Rosow C. editors. Clin- 
ical anesthesia procedures of the Massachu.setts General Hospital, 
.ith ed. Philadelphia: Lippincott-Raven; 1998:204-222. 

4. Sellick BA. Cricoid pressure to control regurgitation of stoinach 
contents during induction of anesthesia. Lancet 1961:2:404^06. 

5. Benumof JL. Scheller MS. The importance of transtracheal jet ven- 
tilation in the management of the difficult airway (review). Anes- 
thesiology 1989;71(.')):769-778. 

6. Schwartz DE. Malthay MA. Cohen NH. Death and other complica- 
tions of emergency airway management in critically ill adults: a 
prospective investigation of 297 tracheal intubations. Anesthesiol- 
ogy 199.'):82(2):.167-.376. 

7. Adnet F, Lapostolle F, Borron SW. Hennequin B. Leclercq G. Fleury 
M. Optimization of glottic exposure during intubation of a patient 
lying supine on the ground. Am J Emerg Med I997;l5(6):.'i.'i.')-,5.'i7. 

8. Adnet F. Cydulka RK. Lapandry C. Emergency tracheal intubation 
of patients lying supine on the ground: influence of operator body 
position. Can J Anaesth l998;45(3):266-269. 

9. Walls RM. Manageinent of the difficult airway in the trauma patient. 
Emerg Med Clin North Am 1998;l6(l):4.'i-6l. 

10. American Heart Association. Adjuncts for airway control, ventila- 
tion, and oxygenation. In: Cummins R. editor. Textbook of advanced 
cardiac life support. Dallas: American Heart Association; 1994:2.1- 
2.17. 

1 1 . Suderman VS. Crosby ET, Lui A. Elective oral tracheal intubation in 
cervical spine-injured adults. Can J Anaesth 1991;38(6):785-789. 

12. 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 I99l;9(6):.'i3.v.'i38. 

13. American Heart Association. Essentials of ACLS. In: Cummins R. 
editor. Textbook of advanced cardiac life support. Dallas: American 
Heart Association; 1994:1.1-1.77. 

14. Campbell WH. Rigid laryngoscopes. In: Roberts J. editor. Clinical 
management of the airway. Philadelphia: WB Saunders; 1994:134- 
1.39. 

15. Rubsamen R. Managing the airway outside of the operating room. 
In: Roberts J. editor. Clinical management of the airway. Philadel- 
phia: WB Saunders; 1994:100-107. 

16. Matthews AJ. Johnson CJ. Goodman NW. Body posture during sim- 
ulated tracheal intubation. Anaesthesia 1998;.'i3(4):33 1-334. 

17. Vanner RG. Clarke P. Moore WJ, Raftery S. The effect of cricoid 
pressure and neck support on the \'iew at laryngoscopy. Anaesthesia 
1997;.52(9):896-9(X). 

18. Roberts JR. Spadafora M. Cone DC. Proper depth placement of oral 
endotracheal tubes in adults prior to radiographic confirmation. Acad 
Emerg Med l99.';;2(l):20-24. 

19. Caroline NL. The airway. In: Caroline N, editor. Emergency care in 
the streets. Boston: Little. Brown; 1994:63-1 12. 

20. Benuinof JL. Dagg R, Benumof R. Critical hemoglobin desaturation 
will occur before return to an unparalyzed state following I mg/kg 
intravenous succinylcholine. Anesthesiology 1997;87(4);979-982. 



Respiratory Care • June 1999 Vol 44 No 6 



625 



Orotracheal Intubation Outside the Operating Room 



21. Ligier B, Buchman TG, Breslow MJ. Deutschman CS. The role of 
anesthetic induction agents and neuromuscular blockade in the en- 
dotracheal intubation of trauma victims. Surg Gynecol Obstet 1991 ; 
173(6):477^81. 

22. Dufour DG, Larose DL, Clement SC. Rapid sequence intubation in 
the emergency department. J Emerg Med 1995;13(5):705-710. 

23. Nayyar P, Lisbon A. Non-operating room emergency airway man- 
agement and endotracheal intubation practices: a survey of anesthe- 
siology program directors. Anesth Analg 1997;85{l):62-68. 

24. Ma OJ, Atchley RB, Hatley T, Green M, Young J, Brady W. Intu- 
bation success rates improve for an air medical program after im- 
plementing the use of neuromuscular blocking agents. Am J Emerg 
Med 1998;16(2):125-127. 

25. Slater EA, Weiss SJ, Ernst AA, Haynes M. Preflight versus en route 
success and complications of rapid sequence intubation in an air 
medical service. J Trauma 1998;45(3):588-592. 

26. Ma OJ, Bentley B 2nd, Debehnke DJ. Airway management practices 
in emergency medicine residencies. Am J Emerg Med 1995; 13(5): 
501-504. 

27. Sakles JC, Laurin EG, Rantapaa AA, Panacek EA. Airway manage- 
ment in the emergency department: a one-year study of 610 tracheal 
intubations. Ann Emerg Med l998;31(3):325-332. 

28. Ovassapian A, Randel GI. The role of the fiberscope in the critically 
ill patient. Crit Care Clin 1995;! 1(1):29-51. 

29. Hughes S, Smith JE. Nasotracheal tube placement over the fibreoptic 
laryngoscope. Anaesthesia 1996;51(1 1):1026-1028. 

30. Weis FR, Hatton MN. Intubation by use of the light wand: experi- 
ence in 253 patients. J Oral Maxillofac Surg 1989;47(6):577-581. 

31. Hardwick WC, Bluhm D. Digital intubation. J Emerg Med 1984; 
I (4):3 17-320. 

32. Vacanti CA, Roberts JT. Blind oral intubation: the development and 
efficacy of a new approach. J Clin Anesth I992;4(5):399-401. 

33. Kreienbuhl G. Verification of endotracheal tube placement [in Ger- 
man]. Anaesthetist 1992;41(9):57 1-581. 

34. Birmingham PK, Cheney FW, Ward RJ. Esophageal intubation: a 
review of detection techniques. Ane.sth Analg 1986;65(8):886-891. 

35. Denman WT, Hayes M, Higgins D, Wilkinson DJ. The Fenen COj 
detector device: an apparatus to prevent unnoticed oesophageal in- 
tubation. Anaesthesia 1990;45(6);465^67. 

36. Omato JP, Shipley JB, Racht EM, Slovis CM, Wrenn KD, Pepe PE, 
et al. Multicenter study of a portable, hand-size, colorimetric end- 
tidal carbon dioxide detection device. Ann Emerg Med 1992;2I(5): 
518-523. 

37. Bhende MS, Thompson AE, Cook DR, Saville AL. Validity of a 
disposable end-tidal CO2 detector in verifying endotracheal tube 



placement in infants and children. Ann Emerg Med 1992;21(2): 
142-145. 

Falk JL, Rackow EC, Weil MH. End-tidal carbon dioxide concen- 
tration during cardiopulmonary resuscitation. N Engl J Med 1988; 
3I8(10):607-611. 

Higgins D, Hayes M, Denman W, Wilkinson DJ. Effectiveness of 
using end-tidal carbon dioxide concentration to monitor cardiopul- 
monary resuscitation. BMJ 1990;300(6724):581. 
Bozeman WP, Hexter D, Liang HK, Kelen GD. Esophageal detector 
device versus detection of end-tidal carbon dioxide level in emer- 
gency intubation. Ann Emerg Med l996;27(5):595-599. 
Esophageal intubation (letter). Anesth Analg 1987;66(5):481^83. 
Linko K, Paloheimo M, Tammisto T. Capnography for detection of 
accidental oesophageal intubation. Acta Anaesthesiol Scand 1983; 
27(3): 199-202. 

Sum-Ping ST, Mehta MP, Anderton JM. A comparative study of 
methods of detection of esophageal intubation. Anesth Analg 1989; 
69(5):627-632. 

Mizutani AR, Ozaki G, Benumof JL, Scheller MS. Auscultation 
cannot distinguish esophageal from tracheal passage of tube. J Clin 
Monit l991;7(3):232-236. 

Patil VU, Stehling LC, Zauder HL. Another use for the fiberoptic 
bronchoscope (letter). Anesthesiology 1981;55(4):484-485. 
Williams KN, Nunn JF. The oesophageal detector device: a prospec- 
tive trial on 100 patients. Anaesthesia 1989;44(5):412^14. 
Knottenbelt JD. The suction test for oesophageal placement of the 
endotracheal tube using an oesophageal detector device: caution is 
required with inexperienced operators. Eur J Emerg Med 1994; 1(4): 
173-174. 

Lang DJ, Wafai Y, Salem MR, Czinn EA, Halim AA, Baraka A. 
Efficacy of the self-inflating bulb in confirming tracheal intubation 
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 



Respiratory Care • June 1999 Vol 44 No 6 



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 



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 



630 



Respiratory Care • June 1999 Vol 44 No 6 



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) 





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 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- 



632 



Respiratory Care • June 1999 Vol 44 No 6 



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 



634 



Respiratory Care • June 1999 Vol 44 No 6 



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 



Respiratory Care • June 1999 Vol 44 No 6 



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.-^- 



636 



Respiratory Care • June 1999 Vol 44 No 6 



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 



Respiratory Care • June 1999 Vol 44 No 6 



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. 

REFERENCES 

1 . Peterson BD. Heated humidifiers; structure and function. Respir Care 
Clin N Am 1998;4(2):243-260. 

2. Walker AK, Bethune DW. A comparative study of condenser hu- 
midifiers. Anaesthesia I976;3I(8):1086-I093. 

3. Dery R. The evolution of heat and moisture in the respiratory tract 
during anaesthesia with a non-rebreathing system. Can Anaesth See 
J 1973;20(3):296-309. 

4. Ingelstedt S. Studies on conditioning of respired air in the respiratory 
tract. Acta Otolaryngol 1956;l31(Suppl);7-21. 

5. Dery R. Pelletier J, Jacques A, Clavet M, Houde JJ. Humidity in 
anesthesiology. 3. Heat and moisture patterns in the respiratory tract 
during anaesthesia with the semi-closed system Can Anaesth Soc J 
1967;14(4):287-295. 

6. Burton JD. Effects of dry anaesthetic gases on the respiratory mu- 
cous membrane. Lancet 1962;1:235-238. 

7. Chalon J, Loew DAY, Malebranche J. Effects of dry anesthetic gases 
on tracheobronchial epithelium. Anesthesiology 1 972;37(3);338-343. 

8. Fonkalsrud EW, Sanchez M, Higashijima I. Arima E. A comparative 
study of the effects of dry vs. humidified ventilation on canine lungs. 
Surgery 1975;78(3);373-380. 

9. Forbes AR. Humidification and mucus flow in the intubated trachea. 
Br J Anaesth 1973;45(8);874-878. 

10. AARC. Clinical Practice Guideline. Humidification during mechan- 
ical ventilation. Respir Care l992;37(8);887-890. 

1 1 . American Association for Respiratory Care. Consensus statement on 
the essentials of mechanical ventilators. Respir Care 1992;37(9): 
1000-1008. 

12. Hess DR. Branson RD. Humidification: humidifiers and nebulizers. 
In: Branson RD. Hess DR. Chatburn RL. editors. Respiratory care 
equipment. Philadelphia: JB Lippincott; 1995. 

13. Miyao H. Hirokawa T, Miyasaka K. Kawazoe T. Relative humidity, 
not absolute humidity, is of great importance when using a humid- 
ifier with a heating wire. Crit Care Med 1992;20(5):674-679. 

14. Chatburn RL. Physiologic and methodologic is.sues regarding hu- 
midity therapy (editorial). J Pediatr 1989;l 14(3):416-420. 

15. Rhame FS. Streifel A, McComb C, Boyle M. Bubbling humidifiers 
produce microaerosols which can carry bacteria. Infect Control 1986; 
7(8):403^07. 

16. Goularte TA, Manning MT, Craven DE. Bacterial colonization in 
humidifying cascade reservoirs after 24 and 48 hours of continuous 
mechanical ventilation. Infect Control 1987;8C5):20O-203. 



Respiratory Care • June 1999 Vol 44 No 6 



639 



HUMIDIFICATION FOR PATIENTS WITH ARTIFICIAL AlRWAYS 



17. Shanks CA. Clinical anesthesia and the multiple-gauze condenser- 
humidifier. Br J Anaesth 1974;46(10):773-777. 

18. Mapelson WW. Morgan JG. Hillard ER. Assessment of conden.ser 
humidifiers with special reference to the multiple-gauze model, Br 
Med J 1963;l:3()0-30.'i. 

19. Branson RD, Davis K Jr. Evaluation of 21 passive humidifiers ac- 
cording to the ISO 9360 standard: moisture output, dead space, and 
flow resistance. Respir Care 1 996:41 (8):736-743. 

20. Medical devices directorate evaluation. Department of Health, Scot- 
tish Home and Health Department. Welsh Office and Department of 
Health and Social Services Northern Ireland. 

21. Cigada M, Elena A. Soica M. Damia G. The efficiency of twelve 
heat and moisture exchangers: an in vitro evaluation. Intensive Care 
World 1990;7:98-101. 

22. Shelly M. Bethune DW. Latimer RD. A comparison of five heat and 
moisture exchangers. Anaesthesia 1986:4l(.'5):,'527-,'532. 

23. Weeks DB. Ramsey FM. Laboratory investigation of six artificial 
noses for use during endotracheal anesthesia. Anesth Analg 1983; 
62(8):758-763. 

24. Mebius C. A comparative evaluation of disposable humidifiers. Acta 
Anaesthesiol Scand I983;27(5):403^09. 

25. Evaluation report: heat and moisture exchangers. J Med Eng Technol 
1987;! 1{3):1 17-127. 

26. Ogino M, Kopotic R, Mannino FL. Moisture-conserving efficiency 
of condenser humidifiers. Anaesthesia 198,5;40(10):990-99.5. 

27. Health Devices. Heat and moisture exchangers. 1983;12:1.'>.'5-166. 

28. Unal N. Pompe JC, Holland WP, Gultuna I, Huygen PE, Jabaaij K, 
et al. An experimental set-up to test heat-moisture exchangers. In- 
tensive Care Med I99.'5;21(2):142-148. 

29. Annual book of ASTM standards: Fl 690-96 standard specification 
for humidifiers for medical use. Part 1: general requirements for 
active humidification systems. Section 13: medical devices and ser- 
vices. Volume 13.01: medical devices: emergency medical services. 
West Conshohocken PA: American Society for Testing Materials; 
1996:1078-1092. 

30. International Organization for Standardization 1992. ISO 9360: an- 
aesthetic and respiratory equipment — heat and moisture exchangers 
for use in humidifying respired ga.ses in humans. Geneva, Switzer- 
land: International Organization for Standardization; 1992. 

31. Branson RD. Cainpbell RS. Davis K Jr. Effect of expiratory tlow on 
moisture output of passive humidifiers as measured by the ISO 9360 
standard. Respir Care 1997;42( 10):960-964. 

32. Ploysongsang Y, Branson RD, Rashkin MC. Hurst JM. Effect of 
flowrate and duration of use on the pressure drop across six artificial 
noses. Respir Care 1989;34(10):902-907. 

33. Nishimura M. Nishijiina MK, Okada T, Taenaka N. Yoshiya I. Com- 
parison of flow-resistive work load due to humidifying devices. Chest 
1990;97(3):6(M)-604. 

.34. Manthous CA, Schmidt GA. Resistive pressure of a condenser hu- 
midifier in mechanically ventilated patients. Crit Care Med 1994; 
22(11): 1792- 1795. 

35. Chiaranda M. Verona L. Pinainonli O. Dominioni L, Minoja G, 
Conti G. Use of heat and moisture exchanging (HME) filters in 
mechanically ventilated ICU patients: influence on airway flow-re- 
sistance. Intensive Care Med 1993;19(8):462-466. 

36. McEwan AI, Dowell L, Karis JH. Bilateral tension pneumothorax 
caused by a blocked bacterial filter in an anesthesia breathing circuit. 
Anesth Analg 1993;76(2):440-442. 

37. l.oeser EA. Water-induced resistance in disposable respiratory-cir- 
cuit bacterial filters. Anesth Analg 1978:57(2):269-27l. 

38. Buckley PM. Increase in resistance of in-line breathing filters in 
humidified air. Br J Anaesth 1984;56(6):637-643. 



39. Tenaillon A. Cholley G, Boiteau R. Perrin-Gachadoat D, Burdin M. 
Heat and inoisture exchanging bacterial filters versus heated humid- 
ifier in long-term inechanical ventilation. Care Crit III 1991 ;7:56-66. 

40. Prasad KK, Chen L. Complications related to the use of a heat and 
inoisture exchanger (letter). Anesthesiology I990:72(5):958. Pub- 
lished erratum appears in Anesthesiology 1990;73(2):72. 

41. Martinez FJ, Pietchel S, Wise C, Walek J, Beamis JF. Increased 
resistance of hygroscopic condenser humidifiers when using a closed 
circuit suction system. Crit Care Med 1994:22(10): 1668-1673. 

42. Stacey MR, A.sai T, Wilkes A, Hodzovic I. Obstruction of a breath- 
ing system filler (letter). Can J Anaesth 1996;43(12):1276. 

43. Smith CE, Otworth JR, Kaluszyk P. Bilateral tension pneumothorax 
due to a defective anesthesia breathing circuit filter. J Clin Anesth 
1991;3(3):229-234. 

44. Koga Y. Iwatsuki N. Takahashi M, Hashimoto Y. A hazardous de- 
fect in a humidifier (letter). Anesth Analg 1 990:7 1(6):7 12. 

45. Prados W. A dangerous defect in a heat and moisture exchanger 
(letter). Anesthesiology 1989;71(5):804. 

46. lotti GA, Olivei MC, Palo A, Galbusera C. Veronesi R. Comelli A, 
et al. Unfavorable mechanical effects of heat and moisture exchang- 
ers in ventilated patients. Intensive Care Med I997;23(4):399^05. 

47. Pelosi P. Solca M. Ravagnan I. Tubiolo D, Ferrario L. Gattinoni L. 
Effects of heat and moisture exchangers on minute ventilation, ven- 
tilatory drive, and work of breathing duiing pressure-support ventilation 
in acute respiratory failure. Crit Care Med I996;24(7):l 184-1 188. 

48. Conti G. De Blasi RA, Rocco M, Pelaia P, Antonelli M, Bufi M, et 
al. Effects of heat-moisture exchangers on dynamic hyperinflation of 
mechanically ventilated COPD patients. Intensive Care Med 1990; 
16(7):441-443. 

49. Le Bourdelles G, Mier L, Fiquet B. Djedaini K, Saunion G, Coste F, 
Dreyfuss D. Comparison of the efTects of heat and moisture exchang- 
ers and heated humidifiers on ventilation and gas exchange during 
weaning trials from mechanical ventilation. Che.st 1996:1 1 0(5): 1294- 
1298. 

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. 



640 



Respiratory Care • June 1999 Vol 44 No 6 



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. 



Respiratory Care • June 1999 Vol 44 No 6 



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 



Respiratory Care • June 1999 Vol 44 No 6 



645 



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- 



646 



Respiratory Care • June 1999 Vol 44 No 6 



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 



1 . Goto T, Roberts JT. The nasal approach to intubation. In: Roberts J, 
editor. Clinical management of the airway. Philadelphia: WB Saun- 
ders 1994:173-186. 

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: 
anatomic considerations and techniques. Respir Care 1 999:44(6)6 1 5- 
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 
tubes in adults prior to radiographic confirmation. Acad Emerg Med 
1997;4(12):1111-1114. 

15. Harris RD. Gillett MJ. Joseph AP, Vinen JD. An aid to blind na.sal 
intubation. J Emerg Med 1998:16(l):93-95. 

16. Ovassapian A, Randel GI. The role of the fiberscope in the critically 
ill patient. Crit Care Clin 1995:1 l(l):29-5l. 

17. Dost P, Armbruster W. Nasal turbinate dislocation caused by naso- 
tracheal intubation. Acta Anaesthesiol Scand 1997;41(6):795-796. 

18. Berry FA Jr. Blankenbaker WL, Ball CG. Comparison of bacteremia 
occurring with nasotracheal and orotracheal intubation. Anesth Analg 
l973:52(6):873-876. 

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 
nasotracheal tube after facial fracture: a rare complication. J Emerg 
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. 



Respiratory Care • June 1 999 Vol 44 No 6 



647 



Nasotracheal Intubation 



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 



648 



Respiratory Care • June 1999 Vol 44 No 6 



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 



Respiratory Care • June 1999 Vol 44 No 6 



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 



6.51 



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. 



652 



Respiratory Care • June 1999 Vol 44 No 6 



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 



654 



Respiratory Care • June 1 999 Vol 44 No 6 



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 



655 



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 



656 



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. 

REFERENCES 

1 . King BR. Baker MD. Braitman LE. Seidl-Friedman J, Schreiner MS. 
Endotracheal tube selection in children: a complication of four meth- 
ods. Ann Einerg Med l993;22(3):530-5.^4. 

2. Kemper KJ, Benson MS, Bishop MJ. Predictors of postextubation 
stridor in pediatric trauma patients. Crit Care Med 1991; 19(3 );352- 
355. 

3. Seid AB. Godin MS. Pransky SM. Kearns DB. Peterson BM. The 
prognostic value of endotracheal tube-air leak following tracheal 
surgery in children. Arch Otolaryngol Head Neck Surg 1991:1 17(8): 
880-882. 

4. Schwartz RE. Stayer SA. Pasquariello CA. Tracheal tube leak test — is 
there inter-observer agreement? Can J Anaesth 1993:40(1 1):1 (M9- 
1052. 

5. Deakers TW. Reynolds G. Stretton M, Newth CJ. Cuffed endotra- 
cheal tubes in pediatric intensive care. J Pediatr 1994:l25(l):57-62. 

6. Khine HH. Corddry DH. Kettrick RG. Martin TM, McCloskey JJ, 
Rose JB. et al. Comparison of cuffed and uncutTed endotracheal 
tubes in young children during general anesthesia. Anesthesiology 
1997:86(3):627-631. discussion 27A. 

7. Robertson C, Orr R. Allen B, et al. Estimation of endotracheal tube 
depth placement in children (abstract). Crit Care Med 1 998:26: A58 

8. Freeman JA, Fredricks BJ, Best CJ. Evaluation of a new method for 
determining tracheal tube length in children. Anaesthesia 1995; 
50(12): 1050-1052. 

9. Levy FH, Bratton SL, Jardine DS. Routine chest radiographs fol- 
lowing repositioning of endotracheal tubes are necessary to assess 
correct position in pediatric patients. Chest 1994:106(5):1508-1510. 

10. O'Sullivan BP. Frassica JJ. Rayder SM. Tracheal bronchus: a cause 
of prolonged atelectasis in intubated children. Chest 1998:113(2): 
537-540. 

1 1. Rivers G. Gabram S. Schwartz R. et al. A comparison of intubation 
success in pediatric and adult populations (abstract). J Air Med Trans- 
port 1991:10:29. 

12. Nakayama DK. Gardner MJ. Rowe MI. Emergency endotracheal 
intubation in pediatric trauma. Ann Surg 1990:21 1(2):218-223. 

1 3. Berry AM. Brimacoinbe JR. Verghese C. The laryngeal mask airway 
in emergency medicine, neonatal resuscitation, and intensive care 
medicine. Int Anesthiol Clin 1998:.36(2):91-109. 

14. O'Neill B. Templeton JJ, Caramico L. Schreiner MS. The laryngeal 
mask airway in pediatric patients: factors affecting ease of use during 
insertion and einergence. Anesth Analg l994:78(4):659-662. 

15. Tait AR. Pandit UA. Voepel-Lewis T, Munro HM, Malviya S. Use 
of the laryngeal mask airway in children with upper respiratory tract 
infections: a comparison with endotracheal intubation. Anesth Analg 
1998;86(4):706-711. 



Respiratory Care • June 1999 Vol 44 No 6 



657 



Issues in Airway Management in Infants and Children 



16. Lopez-Gil M, Brimacombe J, Alvarez M. Safety and efficacy of the 
laryngeal mask airway: a prospective survey of 1400 children. An- 
aesthesia 1996;51(10):969-972. 

17. Smyth AR, Bowhay AR, Heaf LJ, Smyth RL. The laryngeal mask 
airway in fiberoptic bronchoscopy. Arch Dis Child 1996;75(4):344- 
345. 

18. Patel A, Venn PJ, Barham CJ. Fibreoptic intubation through a la- 
ryngeal mask airway in an infant with Robin sequence. Eur J An- 
aesth 1998;15(2):237-239. 

19. Paterson SJ, Byrne PJ, Molesky MG, Seal RF, Finucane BJ. Neo- 
natal resuscitation using the laryngeal mask airway. Anesthesiology 
1 994:80(6): 1248- 1 253, discussion 27A. 

20. Brimacombe J, Gandini D. Resuscitation of neonates with the laryn- 
geal mask-a caution (letter). Pediatrics I995;95(3):453^54. 

2 1 . Guidelines for prevention of nosocomial pneumonia. Center for Dis- 
ease Control and Prevention. MMWR Morb Mortal Wkly Rep 1997; 
46(RR-l):l-79 

22. Black AE, Hatch DJ, Nauth-Misir N. Complications of nasotracheal 
intubation in neonates, infants and children: a review of 4 years' 
experience in a children's hospital. Brit J Anaesth 1990;65(4):461- 
467. 

23. Way WL, Sooy FA. Histologic changes produced by endotracheal 
intubation. Ann Otol Rhinol Laryngol 1965;74(3):799-8I2. 

24. Koka BV, Jeon IS, Andre JM, Mackay I, Smith RM. Postintubation 
croup in children. Anesth Analg 1977;56(4):501-505. 

25. Litman RS, Keon TP. Po.st-intubation croup in children (letter). An- 
esthesiology 1991;75(6):1 122-1 123. 

26. Tobias JD. Heliox in children with airway obstruction. Pediatr Emerg 
Care 1997;13(l):29-32. 

27. Papamoschou D. Theoretical validation of the respiratory benefits of 
helium-oxygen mixtures. Respir Physiol I995;99(I):I83-I90. 

28. Kemper KJ, Ritz RH, Benson MS, Bishop MS. Helium-oxygen mix- 
ture in the treatment of postextubation stridor in pediatric trauma 
patients. Crit Care Med 1991;19(3):356-359. 

29. Anene O, Meert K, Uy H, Simpson P, Sarnaik AP. Dexamethasone 
for the prevention of postextubation airway obstruction: a prospec- 
tive, randomized, double-blind, placebo-controlled trial. Crit Care 
Med 1996;24(10):1666-I669. 

30. Noren JG, Ranggard L, Klingberg G, Persson C, Nilsson K. Intuba- 
tion and mineralization di.strubances in the enamel of primary teeth. 
Acta Odontol Scand 1993;51(5):271-275. 

31. McEniery J, Gillis J, Kilham H, Benjamin B. Review of intubation 
in severe laryngotracheobronchitis. Pediatrics l991;87(6):847-853. 

32. Geelhoed GC. Sixteen years of croup in a Western Australian teach- 
ing hospital: effects of routine steroid treatment. Ann Emerg Med 
l996;28(6):62l-626. 

33. Johnson DW, Schuh S, Koren G, Jaffee DM. Outpatient treatment of 
croup with nebulized dexamethasone. Arch Pediatr Adolesc Med 
I996;l50(4):349-355 



34. Johnson DW, Jacobson S, Edney PC, Hadfield P, Mundy ME, Schuh 
S. A comparison of nebulized budesonide, intramuscular dexameth- 
asone, and placebo for moderately severe croup. New Engl J Med 
1998;339(8):498-503. 

35. Tibballs J, Shann FA, Landau LI. Placebo-controlled trial of pred- 
nisolone in children intubated for croup. Lancet 1992:340(8822): 
745-748. 

36. Eckel HE, Widemann B, Damm M, Roth B. Airway endoscopy in 
the diagnosis and treatment of bacterial tracheitis in chidren. Int 
J Pediatr Otorhinolaryngol 1993;27(2):147-157. 

37. Sendi K. Crysdale WS, Yoo J. Tracheitis: outcome of 1,700 cases 
presenting to the emerency department during two years. J Otolar- 
yngol; 1 992;2 1 ( 1 ):20-24. 

38. Singh-Naz N, Sprague BM, Patel KM, Pollack MM. Risk factors for 
nosocomial infection in critically ill children: a prospective cohort 
study. Crit Care Med 1996;24(5):875-878. 

39. Fayon MJ, Tucci M, Lacroix J, Farrell CA, Gauthier M, Latleur L. 
Nadeau D. Nosocomial pneumonia and tracheitis in a pediatric in- 
tensive care unit: a prospective study. Am J Respir Crit Care Med 
1997; 155(1): 162-1 69. 

40. Bell LM, Baker MD, Beatty D, Taylor L. Infections in severely 
traumatized children. J Pediatr Surg 1992:27(1 1):1394-1398. 

41. Hjuler IM, Hansen MB, Olsen B, Renneberg J. Bacterial coloniza- 
tion of the larynx and trachea in healthy children. Acta Paediatr 
1995;84(5):566-568. 

42. Morar P. Singh V. Jones AS, Hughes J, van Saene R. Impact of 
tracheotomy on colonization and infection of lower airways in chil- 
dren requiring long-term ventilation: a prospective observational co- 
hort study. Chest 1998;1 13(l):77-85. 

43. Bos AP, Tibboel D, Hazelbroek FW, Hoeve H, Meradji M, Malenaar 
JC. Sinusitis: hidden source of sepsis in postoperative pediatric in- 
tensive care patients. Crit Care Med 1989;l7(9):886-888. 

44. Wald ER. Microbiology of acute and chronic sinusitis in children 
and adults. Am J Med Sci 1998;3 16(1): 13-20. 

45. Brook, I. Microbiology of nosocomial sinusitis in mechanically ven- 
tilated children. Arch Otolaryngol Head Neck Surg 1 998; 124(1 ):35- 
38. 

46. Zeitouni A, Manoukian J. Tracheotomy in the first year of life. J 
Otolaryngol 1993;22(6):431^34. 

47. Friedberg J, Giberson W. Failed tracheotomy decannulation in chil- 
dren. J Otolaryngol 1992;21(6):404^08. 

48. MacArthur CJ, Kearns GH. Healy GB. Voice quality after laryngo- 
tracheal reconstruction. Arch Otolaryngol Head Neck Surg 1994; 
120(6):641-647. 

49. Tobias JD. Airway management for pediatric emergencies. Pediatr 
Ann 1996;25(6):3 17-328. 

50. Practice guidelines for management of the difficult airway. A report 
by the American Society of Anesthesiologists Task Force on Man- 
agement of the Difficult Airway. Anesthesiology 1993;78(3):597- 
602. 



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- 



658 



Respiratory Care • June 1999 Vol 44 No 6 



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 



661 



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 



Respiratory Care • June 1 999 Vol 44 No 6 



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 



668 



Respiratory Care • June 1999 Vol 44 No 6 



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- 



Respiratory Care • June 1999 Vol 44 No 6 



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 



Respiratory Care • June 1999 Vol 44 No 6 



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 



Respiratory Care • June 1999 Vol 44 No 6 



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. 



REFERENCES 

1 . Seegobin RD, Van Hasselt GL. Endotracheal cuff pressure and tra- 
cheal mucosal blood flow: endoscopic study of effects of four large 
volume cuffs. Br Med J (Clin Res Ed) l984;288(6422):965-968. 

2. Bunegin L, Albin MS. Smith RB. Canine tracheal blood How after 
endotracheal tube cuff inflation during nonnotension and hypoten- 
sion. Anesth Analg 1993:76(5): 108.V1()90. 

3. Pavlin EG. VanNimwegan D. Hornbein TF. Failure'of a high-com- 
pliance low-pressure cuff to prevent aspiration. Anesthesiology 197.'S; 
42(2):216-219. 

4. Fischer CG, Cook DR. Endotracheal tube cuff pressure in the use of 
nitrous oxide (letter). Anesth Analg I99l:73(l):99. 

5. Bernhard WN. Yost L. Joynes D. Cathalls S, Turndorf H. Iniracuff 
pressures in endotracheal and tracheostomy lubes: related cuff phys- 
ical characteristics. Chest 1985;87(6):72()-72.'i. 

6. Macrae W. Wallace P. Aspiration around high-volume, low-pressure 
endotracheal cuff. Br Med J 1981:383(6.301 ):122(). 

7. Burns SM, Shasby DM. Burke PA. Controlled pressure cuffed en- 
dotracheal tubes may not be controlled (letter). Chest 1983:83(1): 
158-159. 

8. Brodsky JB. Adkins MO. Gaba DM. Bronchial cuff pressures of 
double-lumen tubes. Anesth Analg 1989:69(5):6()8-61(). 



Respiratory Care • June 1999 Vol 44 No 6 



681 



Sp[;Cial PukPosK Endotracheal Tubes 



10. 



12. 
13. 

14. 

15. 
16. 

17. 

18. 

19. 
20. 
21. 

22 
23. 
24. 

25. 

26. 

27. 



29. 



30. 



31. 



Claphajii MCC. Vuughuii RS. Bruiichiul inlubalion: a comparison 
bclwccii pol>\iii>l chloride and red rubber double lumen tubes. An- 
aesthesia 19X5:40(1 I ):1 II 1-1 114. 

Brodskj JB. BenunHilJL. Ehrenwerth J, O/aki GT. Depth of place- 
ment ollell double-lumen endobionchial tubes. Aneslh Analg 1991; 
73(5);570-572. 

Lieberman D, Liltlelord J, Horan I'. Unruh H. Placement of left 
double-lumen ciidotracheal lubes with or without a stylette. Can J 
Anacslh 1 996:43(3):238-242. 

Benumof JL. The position of a double-lumen lube .should be rou- 
tinely determined by fiberoptic bronchoscopy (editorial). J Cardio- 
ihorac Vase Ano.sth 1993;7:513-514. 

Inoue H. Shohtsu A, Ogawa J. Kawada S. Koide S. New device for 
one lung anesthesia: endotracheal tube with moveable blocker (let- 
ter). J Thorac Caidiovasc Suig I982;X3(6):940~94I. 
Vale R. Selective bronchial bk>cking in a small child. Br J Anaesth 
1969;41(5):453-t54. 

Ginsberg RJ. New technique for one-lung anesthesia using an endo- 
bronchial blocker. J Thorac Cardiovasc Surg 198l;82(4):542-546. 
Bcnujnof JL. Partridge BL. SalvatierraC, Keating J. Margin of safety 
in positioning Jiiodcrn double-lumen endotracheal tubes. Anesthesi- 
ology 1987;67(5):729-738, 

Yokota K. Toriumi T. Sari A, Endou S. Mihira M. Auto-positive 
end-expiratory pressure during one-lung ventilation using a double- 
lumen endobronchial tube. Aneslh Analg 1 996;82(5): 1007-1010. 
Gourin A. Garzon AA. Control of hemorrhage in emergency pul- 
monary resection for massive hemoptysis. Chest I975;68(1):I20- 
121. 

Cahill BC. Ingbar DH. Massive hemoptysis: assessment and man- 
agement. Clin Chest Med 1994: I5( I): 147-168. 
Slollcr JK. Diagnosis and management of massive hemoptysis: a 
review. Respir Care l992;37(6):564-578. Discussion: 578-581. 
Sosis MB. What is the safest endotracheal tube for Nd-YAG laser 
surgery? A comparative study. Aneslh Analg l989;69(6):802-804. 
Sosis MB. Which is the safest endotracheal tube for use with the CO, 
laser.' A comparative study. J Clin Anesth 1992;4(3): 217-219. 
Sosis M. Dillon E. Reflection of CO, la.ser radi;ition from laser- 
resistant endotracheal tubes. Anesth Analg 1991 ;73(3):338-340. 
Sprung J. Conlcy S1-. Brov\n M. Unusual case of difficult extubation 
(letter). Anesthesiology 1991:74(41:796. 

Jeckstrom W. Wawersik J. Hoffmann P. et. al. Anesthesiological 
problems of endolaryngeal and endotracheal laser surgery. In: Rudert 
H, Werner JA. editors. Lasers in otorhinolaryngology. and head and 
neck surgery. Adv Otorhrinolaryngol 1995:49:15-19. 
Hess D, Alagar R. Methods of emergency drug administration. Re- 
spir Care I995;4()(5):498-5I2. Discussion: 512-514. 
Barnett CC. Moore I'A, Moore EE. et al. : Tracheal gas insufflation 
is a useful adjunct in permissive hypcrcapnic management of acute 
respiratory distress syndrome. Ani J Surg l996;l72(5):5l8-522. 
Miro AM. Hoffman LA. I asota EJ. Sigler DW. Gowski DT, Lulz J, 
et al. : Tracheal gas insufllalion improves ventilatory efficiency dur- 
ing metacholine-lnduced bronchospasm. J Crit Care I997;I2( I):I3- 
21. 

Levy B. Bollaert PL. Nace L, Larcan A. Intracranial hypertension 
and adult respiratory distress syndrome: usefulness of tracheal gas 
insufflation. J Trauma I995:39(4):799-80I. 

Imanaka 11. Kacniarek KM. Riggi V. Rit/, R. Hess D. Expiratory 
phase and \olnme-adiusled tracheal gas insufflation: a lung model 
study. Crit Care Med 1998:26(5): 939-946. 

(iowski DT. Delgado E. Miro AM. Tasota EJ, Hoffman LA. Pinsky 
VIK. Tracheal gas insufllalion duiing pressure-control ventilation: 



effect of using a pressure relief valve. Crit Care Med 1997;25(1): 
145-152. 

32. Hotchkiss JR Jr, Crooke PS 3rd, Marini JJ. Theoretical interactions 
between ventilator settings and proximal deadspace ventilation dur- 
ing tracheal gas insufflation. Intensive Care Med 1996;22(10);l 1 12- 
1119. 

33. Hoyt JD. Marini JJ. Nahum A. Effect of tracheal gas insufflation on 
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 
catheter via the laryngeal mask airway (letter). Anaesthesia 1993; 
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- 
gery. Anesthesiology I982;56(4):309-310. 

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- 
tion of endotracheal tubes. Anesthesiology l978;49(l):50-52. 

51. Van Den Hoogen EJ. Oudes MJ. Hombergen G, Nijdam HF, Manni 
JJ. The Groningen, Nijdam, and Provox voice prostheses: a prospec- 
tive clinical coiriparison based on 845 replacements. Acta Otolaryn- 
gol (Stockh) 1 996; 11 6(1): II 9- 124. 



682 



Respiratory Care • June 1999 Vol 44 No 6 



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 = 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. 

REFERENCES 

1. Nunn JF. Applied respiratory physiology. Boston: Butterwortti and 
Co. Putilishers Ltd; 1971. 

2. Marini JJ. Respiratory medicine for the house officer. 2nd edition. 
Baltimore: Williams and Wilkins; 19X7 

3. Branson RD. The nuts and bolls of increasing arterial oxygenation: 
devices and techniques. Respir Care 1993;38(6):672-686. Discus- 
sion: 687-689. 

4. Foust ON. Potter WA, Wilons MD, Golden EB. Shortcomings of 
using two jet nebulizers in tandem with an aerosol face mask for 
optimal oxygen therapy. Chest I991:99(6):I346-13.'il. 

5. Poulton E. Oxon D. Left-sided heart failure with pulmonary edema: 
its treatment with the pulmonary plus-pressure machine. Lancet 1936: 
231:981-983. 

6. Barach AL, Martian J. Eckman M. Positive-pressure respiration and 
its application to the treatment of acute pulmonary edema and re- 
spiratory obstruction. Proc Am Soc Invest 1937:16:664-680. 

7. Appendini N, Patessio A. Zanaboni S. Carone M. Gukov B, Donner 
CF. Rossi A. Physiologic effects of positive end-pressure and mask 
pressure support during exacerbations of chronic obstructive pulmo- 
nary disea.se. Am J Respir Crit Care Med 1994:149(.'i):1069-I076. 

8. Rasanen J. Heikkila J. Downs J, Nikki P. Vaisanen I. Viitanen A. 
Continuous positive airway presstne by face mask in acute cardio- 
genic pulmonary edema. Am J Cardiol 198.');.')5(4):296-30(). 

9. Bersten AD, Holt AW, Vedig AE. Skowronski GA. Baggoley CJ. 
Treatment of severe cardiogenic pulmonary edema with continuous 
positive airway pressure delivered by face mask. N Eng J Med 
1991;32.')(26):1825-1830. 

10. Lin M. Chiang H. The efficacy of early continuous positive airway 
pressure therapy in patients with acute cardiogenic pulmonary edema. 
J Formosa Med Assoc 1991;90(8):736-743. 

11. Vaisanen M, Rasanen J. Continuous positive airway pressure and 
supplemental oxygen in the treatment of cardiogenic pulmonary 
edema. Chest 1987;92(3):481-48.S. 

12. Mehta S, Jay GD. Woolard RH. Hipona RA, Connolly EM. Ciniini 
DM, et al. Randomized, prospective trial of bilevel versus continu- 
ous positive airway pressure in acute pulinonary edema. Crit Care 
Med 1997;25{4):620-628. 

13. Brochard L. Mancebo J. Wysocki M. Lofao F. Conti G, Rauss A, et 
al. Noninvasive ventilation for acute exacerbations of chronic ob- 
structive pulmonary disease, N Eng J Med 1995;333( 13):8l7-822. 

14. Vitacca M, Rubini F, Foglio K, Scalvini S. Nava S, Anibrosino N. 
Non-invasive modalities of positive pre.s.sure ventilation improve the 
outcome of acute exacerbations in COLD patients. Intensive Care 
Med I993:93(8):450-455. 

15. Brochard L, Isabey D, Piquet J, Amaro P, Mancebo J, Messadi AA, 
et al. Reversal of acute exacerbations of chronic obstructive lung 
disease by inspiratory assistance with a face mask. N Engl J Med 
1990:323(22): 1523-15.30. 



Respiratory Care • June 1 999 Vol 44 No 6 



697 



Methods to Avoid Intubation 



16. Confalonieri M, Parigi P, Scartabellati A, Aiolfi S, Scorsetti S, Nava 
S, et al. Noninvasive mechanical ventilation improves the immediate 
and long-term outcome of COPD patients with acute respiratory 
failure. Eur Respir J 1996;9(3):422-^30. 

17. 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;15(6):1799- 
1806. 

18. Wysocki M, Trie L, Wolff MA, Millet H, Herman B. Noninvasive 
pressure support ventilation in patients with acute respiratory failure. 
A randomized comparison with conventional therapy. Chest 1995; 
107(3):761-768. 

19. American Respiratory Care Foundation. Consensus statement: non- 
invasive positive pressure ventilation. Respir Care 1997;42(4);365- 
369. 

20. Carrey Z, Gottfried SB, Levy RD. Ventilatory muscle support in 
respiratory failure with nasal positive pressure ventilation. Chest 
1990;97{1):150-158. 

21. Turner RE. NPPV; face versus interface. Respir Care 1997;42(4): 
389-393. 

22. Dal Vecchio L, Polese G, Poggi R, Rossi A. "Intrinsic" positive 
end-expiratory pressure in stable patients with chronic obstructive 
pulmonary disease. Eur Respir J 1990;3(l):74-80. 

23. Meduri GU, Turner RE, Abou-Shala N, Wunderink R, Tolley E. 
Noninvasive positive pressure ventilation via face mask: First-line 
intervention in patients with acute hypercapnic and hypoxemic re- 
spiratory failure. Chest 1996; 109(1): 1 79- 1 93. 

24. Barach AL. U.se of helium as a new therapeutic gas. Proc Soc Exp 
Bio Med 1934;462-464. 

25. Barach AL. The therapeutic use of helium. JAMA 1 936; 107: 1273- 
1275. 

26. Barach AL. The use of helium in the treatment of asthma and ob- 
structive lesions of the larynx and trachea. Ann Intern Med 1935;9: 
739-765. 

27. Barach AL. The use of helium as a new therapeutic gas. Anesth 
Analg 1935;14:210-215. 

28. Wood LD, Engel LA, Griffin P, Despas P, Macklem PT. Effect of 
gas physical properties and flow on lower pulmonary resistance. 
J Appl Physiol I976;41(2):234-244. 

29. Kemper KJ, Ritz RH, Benson MS, Bishop MS. Helium-oxygen mix- 
ture in the treatment of postextubation stridor in pediatric trauma 
patients. Crit Care Med 1991;19(3):356-359. 

30. Kemper KJ, Izenbegr S, Marvin JA, Heimbach DM. Treatment of 
postextubation stridor in a pediatric patient with burns: the role of 
heliox. J Burn Care Rehabil 1990;1 1(4):337-339. 

31. Nelson DS, McClellan L. Helium-oxygen mixtures as adjunctive 
support for refractory viral croup. Ohio State Med J 1982;78(10): 
729-730. 

32. Tobias JD. Heliox in children with airway obstruction. Pediatr Emerg 
Care 1997;13{l):29-32. 

33. Boorstein JM, Boor.stein SM, Humphries GN, Jonhston CC. Using 
helium-oxygen mixtures in the emergency management of acute up- 
per airway obstruction. Ann Emerg Med 1989;18(6):688-690. 

34. Lu TS, Ohmura A, Wong KC, Hodges MR. Helium-oxygen in the 
treatment of upper airway obstruction. Anesthesiology 1976;45(6): 
678-680. 

35. Curtis JL, Mahlmeister M, Fink JB, Lampe G, Matthay MA, Stul- 
barg MS. Helium-oxygen gas therapy. Use and availability for the 
emergency treatment of inoperable airway obstruction. Chest 1986; 
90(3):455-457. 

36. Manthous CA, Hall JB, Caputo MA, Walter J, Klocksieben JM, 
Schmidt GA, Wood LD. Heliox improves pulsus paradoxsus and 
peak expiratory flows in nonintubaled patients with .severe asthma. 
Am J Respir Crit Care Med 1995;151(2 Pt 1):3I0-3I4. 



37. Shiue ST, Gluck EH. The use of helium-oxygen mixtures in the 
support of patients with status asthmaticus and respiratory acidosis. 
J Asthma 1989;26(3):I77-I80. 

38. Kudukis TM, Manthous CA, Schmidt GA, Hall JB, Wylam ME. 
Inhaled helium-oxygen revisited: effect of inhaled helium-oxygen 
during the treatment of status asthmaticus in children. J Pediatr 1997; 
1 30(2):2 17-224. 

39. Kass JE, Castriotta RJ. Heliox therapy in acute asthma. Chest 1995; 
107(3):757-760. 

40. Manthous CA, Morgan S, Pohlman A, Hall JB. Heliox in the treat- 
ment of airflow obstruction: a critical review of the literature. Respir 
Care 1997;42(1 1):1034-1042. 

41 . Hess DR, Acosta FL, Ritz RH, Kacmarek RM, Carmargo CA Jr. The 
effect of heliox on nebulizer function using a beta-agonist broncho- 
dilator. Chest 1999;115(1):184-189. 

42. Rudnitsky GS, Eberlein RS, Schoffstall JM, Mazur JE, Spivey WH. 
Comparison of intermittent and continuously nebulized albuterol for 
treatments of asthma in an urban emergency room. Ann Emerg Med 
1993;22(12):1842-1846. 

43. Levitt MA, Gambrioli EF, Fink JB. Comparative trial of continuous 
nebulization versus metered-dose inhaler in the treatment of acute 
bronchospasm. Ann Emerg Med 1995;26(3):273-277. 

44. Papo MC, Frank J, Thompson AE. A prospective, randomized study 
of continuous versus intermittent nebulized albuterol for severe sta- 
tus asthmaticus in children. Crit Care Med I993;21(10):1479-1486. 

45. Reisner C, Kotch A, Dworkin G. Continuous versus frequent inter- 
mittent nebulization of albuterol in acute asthma: a randomized, 
prospective study. Ann Allergy Asthma Immunol 1995;75(l):41^7. 

46. Shrestha M, Bidali K, Gourlay S, Hayes J. Continuous vs intermit- 
tent albuterol, at high and low doses, in the treatment of severe acute 
asthma in adults. Chest 1 996; 1 10(1 ):42^7. 

47. Schiller IW, Lowell FC, Lynch MT, Franklin W. The effect of he- 
lium oxygen mixtures on pulmonary functions in asthmatic patients. 
J Allergy 1955;ll-14. 

48. Carter ER, Webb CR, Moffitt DR. Evaluation of heliox in children 
hospitalized with severe acute asthma. A randomized crossover trial. 
Chest 1996;109(5):I256-1261. 

49. Wollam CHM. The development of apparatus for intermittent neg- 
ative pressure respiration. Anesthesia 1976;31:666-685. 

50. Lassen HA. A preliminary report on the 1952 epidemic of poliomy- 
elitis in Copenhagen. Lancet 1953;l:37. 

51. Pelteir LF. Obstruction apnea in artificially hyperventilated subjects 
during sleep. J Appl Physiol 1953;5:614. 

52. Bach JR, Penek J. Obstructive sleep apnea complicating negative- 
pressure. ventilatory support in patient with chronic paralytic/restric- 
tive ventilatory dysfunction. Chest 1991;99(6):1386-I393. 

53. Levy RD, Bradley TD, Newman SL, Macklem PT, Martin JG. Neg- 
ative pressure ventilation. Effects on ventilation during sleep in nor- 
mal subjects. Chest 1989;95(l):95-99. 

54. Belman MJ. Soo Hoo GW, Kuei JH. Shadmehr R. Efficacy of pos- 
itive vs negative pressure ventilation in unloading the respiratory 
muscles. Chest l990;98(4):850-856. 

55. Lien T, Wang J, Chang M, Kuo CD. Comparison of BiPAP nasal 
ventilation and ventilation via iron lung in severe stable COPD. 
Chest 1993;104(2):460^66. 

56. Wright J. The respiraid rocking bed in poliomyelitis. Am J Nurs 
1947;47:454-455. 

57. Adamson JP, Lewis L, Stein JD. Application of abdominal pressure 
for artificial respiration. JAMA 1959;169:1613-1617. 

58. Colville P, Shugg C, Ferris BG. Effects of body tilting on respiratory 
mechanics. J Appl Physiol 1956;9:19-24. 

59. Joos TH, Dickin.son DG, Talner NS, Wilson JL. The rocking bed and 
head position. N Eng J Med 1956;255:1089-1090. 



698 



Respiratory Care • June 1999 Vol 44 No 6 



Methods to Avoid Intubation 



60. Gordon AS. Fainer DC. Ivy AC. Artificial respiration: a new method 
and comparative study of different methods in adults. JAMA 1950; 
144:1455-65. 

61. Glenn WW, Brouillette RT, Dentz B, et al. Fundamental consider- 
ations in pacing of the diaphragm for chronic ventilatory insuffi- 
ciency: a multi-center study. PACE 1998:2121-2127. 

62. Glenn WW. Phelps ML. Diaphragm pacing by electrical stimulation 
of the phrenic nerve. Neurosurgery 1985:17(6):974-984. 

63. Bach JR. O'Conner K. Electrophrenic ventilation: a different per- 
spective. J Am Paraplegia Soc 1991;14(1):9-17. 

64. Bach JR. Mechanical insuftlation-exsufflation. Comparison of peak 
expiratory flows with manually assisted and unassisted cough tech- 
niques. Chest I993;104(5):1553-1562. 

65. Hess DR. Noninvasive positive pres.sure ventilation: predictors of 
success and failure for adult acute care applications. Respir Care 
1997:42:4:424^31. 

66. Elliot MW. Steven MH. Phillips GD et al. Noninvasive mechanical 
ventilation for acute respiratory failure. Br Med J 1990:300:358-360. 

67. Chevrolet JC, Jolliet P. Abajo B, Toussi A, Louis M. Nasal positive 
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- 



702 



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 
a savings of more tlian SIOO.OO! 



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: 8247 9861 9 / 
List Price: S29 5. 00 

AMERICAN ASSOCIATION OF 
RESPIRATORY CARE 



SUBSCRIBERS' PRICE: S177.00!^ 



•*...the best single source on the sdence of ventilatory support.... 
•*It is a pleasure to encounter a well-edited and critically written 
volume intended for the most physiologically-oriented of respiratory 
practitioners....bccause of the high level of presentation covering a 
broad range of issues, this volume mertis a prominent place on 
the bookshelves of every investigator and teacliing working 
in the field of respiratory care." — Respiratory Care 



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 



To take advantage of this Special Discoimt, all orders must be 
prepaid and be sure to request the AARC subscribers' price . 

coffer exprics August 15, 1999) 



Three ways to order: 



Toll-free 1800 228 11 60 c^ /Fax 1-914 796-1772 
E-Mail bookorders@dekker.com ^>. 



Marcel Dekker, Inc., 

2/0 .Madison Ave.. New York, .\Y 1 00 1 6 / (21 2-696 9000) 




www.ciekKer.com 




UNIFORM 

REPORTING 



MANUAL 



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. 



*Second Author: 



•Third Author: 



Author Signature/Date, 



Author Signature/Date, 



•Fourth Author: 



Author Signature/Date. 



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 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 

Circle Reader Service No. 1 1 2 Call (800) 333-8646 

Vortran Medical 564 

Circle Reader Service No. 1 27 Call (800) 434-4034 

Westmed Inc 566 

Circle Reader Service No. 104 Call (800) 724-2328 



Copyright Information. Respiratory Care is copyrighted by 
Daedalus Enterprises Inc. Reproduction in whole or in part without the express 
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. 

Subscription Rates, individual subscription rates are $75 per year 
(12 issues), .$145 for 2 years, and $215 for 3 years in the US and Puerto 
Rico. Rates are $90 per year, $ 1 75 for 2 years, and $260 for 3 years in all other 
countries (add $94 per year for air mail). Single copies when available cost 
$7; add $9 for air mail postage to overseas countries. Checks should be 



made payable to RESPIRATORY CARE and sent to the subscription office at 
1 1030 Abies Lane, Dallas TX 75229-4593. 

SUBSCRIPTION Rates for associations. Basic annual subscrip- 
tions are offered to members of associations according to their member- 
ship enrollment: 101-500 members = $13.50/year, 501-1,500 = $13/year; 
1,500-10,000 = $l2.50/year; more than 10,000 = $1 1.50/year. Individual 
subscriptions ar available at these rates: $75/year ( 1 2 issues in the United States 
or Puerto Rico; $90/year in other countries. For information, contact Ray 
Masferrer at (972) 243-2272. 

Change of address. Notify the AARC at (972) 243-2272 as soon as pos- 
sible of any change in address. Note the subscription number (from the 
mailing label) and your name, old address, and new address. Allow 6 
weeks for the change. To avoid charges for replacement copies of missed is- 
sues, requests must be made within 60 days in the US and 90 days in other 
countries. 

Manuscripts. The Journal publishes clinical studies, method/device 
evaluations, reviews, and other materials related to cardiopulmonary med- 
icine and research. Manuscripts may be submitted to the Editorial Office, RES- 
PIRATORY Care, 600 Ninth Avenue, Suite 702, Seattle WA 98104. In- 
structions for authors are printed in every issue. An expanded version of 
the Instructions is available from the editorial office. 

Copyright © 1999, by Daedalus Enterprises Inc. 



720 



RESPIRATORY CARE • JUNE 1999 VOL 44 NO 6 



Small Enough for Homecare.., 

Powerful Enough for Acute Care 




Respiratory Care 
Subscription Form 

U.$. Subscriptions Subscripdom OuMde U A 



1 YR 
(12lssuct) 

2TIB 

(24 Issues) 

3YRS 
(36 Issues) 



D»75 

D'145 

n'215 



0*90 



n»175 



D'2«0 



RcsFfUTOlir Cmi is the most highly 
regarded peer-reviewed scientific 
publication for the Clinician 
participating in the evaluation 
and care of patients with 
cardiopulmonary problems. 
Please print; incomplete forms 
will not be processed. For faster 
service, fax to (972)484-2720 

Endotcd Is a diecfc 
In the amount of 



Oiargetomy; 

D Mastercard 
D Visa 
□ Bill Me 



The New LTVIOOO 
Hlator Delivers 
yerful Functions 
tin a Portable 
figuration 



Signature 



Expiration Date 



Credit Card Number 



Facili^h4ame 



City 



Telephone 



Product 
information 

For AABC membefihip intormaliott, ci 

101 102 103 104 105 

119 120 121 122 123 

137 138 139 140 141 

155 156 157 158 159 

ill 174 175 176 177 

191 192 193 194 195 



Country 




To receive information on the products 
and services mentioned in this issue, 
circle the corresponding category 
number or individual manufacturer's 
number. Fill in your name and address 
and mail this postage-paid card. 
Information will be sent directly to you 
■ from the manufacturer. Please print- 
incomplete forms will not be 
processed. For faster service, fax to 
(609)786-4415 



ircle 101 . For RisPWAicxtr Caw subMrhption in(orm*tion, ciick t02. 

106 107 108 109 110 111 112 113 m 115 116 

124 125 126 127 128 129 130 131 132 133 134 

142 143 144 145 146 147 148 149 150 151 152 

160 161 162 163 164 165 166 167 168 169 170 

178 179 180 181 182 183 184 185 186 187 188 
196 197 198 199 200 

n«M* dKlc no mot« than ISMiflH. 



NWTW 






Tide 




Facility Ham 


Address 


City 


State 


Zip Code 




Country 


Telephone 




* 




Fax 



RE/PIR/KTORy QiRE 







'#♦»' 



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 



Advert] 
in This I: 

California College fc 

Circle Reader Service 

Cardiopulmonary Co 

Circle Reader Service 

DEY Laboratories . . 

Circle Reader Service 

DHD Healthcare . . . 

Circle Reader Service 

Kaiser Permanente. . 

Circle Reader Service 

Maxtec Inc 

Circle Reader Service 



BUSINESS REPLY MAIL 

FIRST-CLASS MAIL PERMIT NO. 2480 Dallas.TX 



NO POSTAGE 

NECESSARY 

IF MAILED 

IN THE 

UNITED STATES 



POSTAGE WILL BE PAID BY ADDRESSEE 

AARC Subscriptions 

ATTN: Beth Binkley 
PO BOX 29686 
Dallas TX 75229-9691 



Copyright Inforiv 

Daedalus Enterprises Inc 
written permission of D; 
photocopy a single artii 
scientific or educational 
photocopies and copies i 
ing, via e-mail (rcjouma 
RATORY Care. Anyom 
material in this journal p 
Respiratory Care i 
proval by the author and 
authors. Reprints for cor 
terprises Inc. For more ii 

Disclaimer. The opii 
of the author and do no 
American Association f 
prises Inc. Neither are th 
for the consequences of t: 
vices described in any ai 

SUBSCRIPTION RATE 

(12 issues), $145 for 2 ; 
Rico. Rates are $90 per yt 
countries (add $94 per yi 
$7; add $9 for air mail 



IIm,I,I,Im.I.I..I.II.ImI,I,..II..I.I IIII...I 



BUSINESS REPLY MAIL 

FIRST-CLASS MAIL PERMIT NO. 881 Riverton, NJ 



NO POSTAGE 

NECESSARY 

IF MAILED 

IN THE 

UNITED STATES 



POSTAGE WILL BE PAID BY ADDRESSEE 



AARC Publications 

PO BOX 11605 
Riverton NJ 08076-7205 




720 



lll,„l..l.ll...l...l.ll..l...l..l.lll....l.l»lil>l 



Small Enough for Home care... 

Powerful Enough for Acute Care 




i ulmonetic Systems' new LTVlOOff" ventilator imparts quality, value, 
and innovation. Showcased in its small package are powerful features that 
redefine portability without compromising functionality. Its unique 
miniaturization technology coupled with its sophisticated pneumatic 
design afford patients maximum mobility for a better quality of life. 

The LTVIOOO is ideal for weaning and chronic use, for children and 
adults, for inter-facility and intra-facility transport, and for acute, sub- 
acute and homecare environments (510k clearance pending for homecare). 

Combine this versatility and technological advancement with an 
affordable price, the LTVIOOO is ventilation at its best. For more informa- 
tion on how the LTVIOOO can improve the quality of your patients' lives, 
Call us at 1-800-754-1914 or e-mail us at info@pulmonetic.com. 

t 
Pulmonetic Systems, Inc. 930 S. Mount Vernon Avenue, Suite 100, Colton, California 92324 Tel: 909-783-2280 
I O Circle 129 on reader service card 



The New LTVIOOO 



Ventilator Delivers 



Powerful Functions 



within a Portable 



Configuration 




Powerful Functions 

Pressure or Volume Control 

Pressure Support 

NPPV 

Flow-Triggering 

Variable Breatti Termination Criteria 

Oxygen Supplementation 

Portable Configuration 

12x10x3incties 
Ligtitweiglit-only 12.6 lbs. 
Internal Battery 
Compressorless Technology 



PulmonBtic SvstRms 



Mind at rest. 



Didphraqm at work. 




The new RFb System-lJ 
Reduce patient anxiety durinc| respiratory retraining. 



Now you can help respiratory patients releam controlled 
(diaphragmatic) breathing by helping them forget all about 
it. The RFb System-1 is a breakthrough biofeedback tool that 
significantly reduces patient anxiety through visualization 
of diaphragmatic breathing. The result is therapy that's 
easier — and less stressful — on both of you. 

A noninvasive sensor reflects diaphragmatic movement 
back to the brain through an audio/visual headset (patient 
can choose between white noise and a musical tone). 




125 Rasbach Street Canastota, NY 13032 USA 

AvvARb'^e.wtw RFb System-1 is a trademark of DHD Healthcare Corporation. 



The patient receives continuous reinforcement of the correct 
deep-breathing technique without electrodes or other 
invasive devices. A computer console makes it easy 
to monitor patient progress with minimal therapist 
involvement. Therapy has been reimbursed under 
Medicare B. For more information, call DHD Healthcare 
toll-free today: 1-800-847-8000. 

DHD 

Healthcare 

Innovations for respiratory care 
DHD Healthcare Corporation 

(315) 697-2221 • FAX: (315) 697-5191 • www.dhd.com 

© 1999 DHD Healthcare Corporation 



& 



Circle 110 on reader service card