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

March 1991 
Volume 36, Number 3 

ISSN 009891 42-RECACP 




A MONTHLY SCIENCE JOURNAL 
36TH YEAR— ESTABLISHED 1956 



1991 Call for Open Forum Abstracts 



Evaluation of Ten Manual Resusci- 
tators from -18°C to 50°C 

Radiographic Opacification follow- 
ing Relief of Endobronchial 
Obstruction: A Case Report 

Oxygen-Conservers, Home Oxy- 
gen Prescriptions, and the Role of 
the Respiratory Care Practitioner 

Symposium Papers: Long-Term 
Mechanical Ventilation 

Establishing Clinical Unweanability 
Placement Alternatives Outside the ICU 
Patient Selection and Discharge Planning 



Theophylline- 
Enigma 



-A Continuing 



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RE/PIRATORy C&RE 

A Monthly Science Journal. Established 1956. Official Journal of the American Association for Respiratory Care. 



EDITORIAL OFFICE 

1 1030 Abies Une 

Dallas TX 75229 

(214) 243-2272 

EDITOR 

Pat Brougher RRT 

ASSOCIATE EDITOR 

Gary Peck RPFT RRT 

ADJUNCT EDITOR 

Philip Kittredge RRT 

MANAGING EDITOR 

Ray Masferrer RRT 

EDITORIAL COORDINATOR 

Donna Stephens 

EDITORIAL BOARD 

Neil Maclntyre MD, Chairman 

Thomas A Barnes EdD RRT 

Richard D Branson RRT 

Robert L Chatburn RRT 

Charles G Durbin Jr MD 

Thomas D East PhD 

Dean Hess MEd RRT 

Robert M Kacmarek PhD RRT 

David J Pierson MD 

James K Stoller MD 

CONSULTING EDITORS 

Frank E Biondo BS RRT 
Howard J Bircnbaum MD 
John G Burford MD 
Bob Dcmers BS RRT 
Douglas B Eden BS RRT 
Donald R Elton MD 
Robert R Pluck Jr MS RRT 
Ronald B George MD 
James M Hursl MD 
Charles G Irvin PhD 
MS Jaslremski MD 
Hugh S Mathewson MD 
Michael McPeck BS RRT 
Richard R Richard BS RRT 
John Shigeoka MD 
R Brian Smith MD 
Jack Wanger RCPT RRT 
JefTrey J Ward MEd RRT 

JOURNAL ASSOCIATES 

Stephen M Ayres MD 
Reutien M Chernlack MD 
Joseph M Civetta MD 
John B Downs MD 
E>onald F Egan MD 
Garelh B Gish MS RRT 
George Gregory MD 
Ake Grenvik MD 
H Frederick Helmholz Jr MD 
John E Hodgkin MD 
William F Miller MD 
Elian J Nelson RN RRT 
Thomas L Peuy MD 
Alan K Pierce MD 
Manning Pontoppidan MD 
John W Severinghaus MD 
Barry A Shapiro MD 

PRODUCTION STAFF 

Donna Knauf 
Jeannie Marchant 
Jude Revoli 

MARKETING DIRECTOR 

Dale Griffiths 

ADVERTISING ASSISTANT 

Beth Binkley 



CONTENTS 



March 1991 
Volume 36, Number 3 



ORIGINAL CONTRIBUTIONS 

161 Evaluation of Ten Manual Resuscitators across an Operational 
Temperature Range of-18°C to 50°C 
by Thomas A Barnes and Deborah L Stockwell — Boston. 
Massachusetts 

173 Total Opacification of the Left Hemithorax after Relief of 
Endobronchial Obstruction: A Case Report 

by Leland Hanowell, David Thurston, Sulpicio Soriano, and Walter R 
Martin — Sacramento, California 

SPECIAL ARTICLES 

178 Oxygen-Conservers, Home Oxygen Prescriptions, and the Role of the 
Respiratory Care Practitioner 
by John W Shigeoka — Salt Lake City, Utah 

SYMPOSIUM PAPERS 

184 Long-Term Mechanical Ventilation Revisited: An Introduction 

by David J Pierson and Roger S Goldstein — Seattle, Washington, and 
Toronto, Ontario, Canada 

186 Establishing Clinical Unweanability 
by James K Stoller — Cleveland, Ohio 

199 Placement Alternatives for Ventilator-Dependent Patients Outside the 
Intensive Care Unit 

by Michael L Nochomovitz, Hugo D Montenegro, Susan Parran, and 
Barbara Daly — Cleveland, Ohio 

205 Long-Term Mechanical Ventilation: Patient Selection and Discharge 
Planning 
by Mary E Gilmartin — Denver, Colorado 

DRUG CAPSULE 

218 Theophylline — A Continuing Enigma 

by Hugh S Mathewson — Kansas City, Kansas 

TEST YOUR RADIOLOGIC SKILL 

222 A Possible Complication of Central Venous Catheterization 

by Curt M Morey, David C Lain, Bjorn Thorarinsson, Arthur A Taft, 
and Shelley C Mishoe — Albany arul Augusta, Georgia, and Baltimore, 
Maryland 



RESPIRATORY CARE (ISSN 00989142) is a monthly publication of Daedalus Enterprises, Inc, for the American Association for Respiratory Care. Copyright ® 1991 

by Daedalus Enterprises Inc, 1 1030 Abies Lane, Dallas TX 75229. All rights reserved. Reproduction in whole or in part without the express, written permission of Daedalus 

Enterprises, Inc, is prohibited. The opinions expressed in any article or editorial are those of the author and do not necessarily reflect the views of Daedalus Enterprises, 

Inc, the Editorial Board, or the American Association for Respiratory Care. Neither can Daedalus Enterprises, Inc, the Editorial Board, or the American Association for 

Respiratory Care be responsible for the consequences of the clinical applications of any methods or devices described herein. 

RESPIRATORY CARE is indexed in Hospital Lileralure Index and in Cumulalive Index to Nursing and Allied Health Literature. 

Subscription Rates: $5.00 per copy; $50.00 per year (12 issues) in the US; $70.00 in all other countries (add $84.00 for air mail). 

Second Class Postage paid at DaDas, TX. POSTMASTER: Send address changes to RESPIRATORY CARE. Daedalus Enterprises. Inc, 11030 AUes Lane. Dallas TX 

75229. 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



147 



SIEMENS 




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MANUSCRIPT SUBMISSION 

Instructions for Authors and Typists is printed near 
the end of every issue of Respiratory Care. 

PHOTOCOPYING & QUOTATION 

PHOTOCOPYING. Any material in this journal 
that is copyrighted by Daedalus Enterprises, Inc. 
may be photocopied for noncommercial purposes 
of scientific or educational advancement. 

QUOTATION. Anyone may, without permission, 
quote up to 500 words of material in this journal 
that is copyrighted by Daedalus Enterprises, Inc., 
provided the quotation is for noncommercial use, 
and provided Respiratory Care is credited. 
Longer quotation requires written approval by the 
author and publisher. 

SUBSCRIPTIONS/CHANGE OF ADDRESS 

Respiratory Care 
1 1030 Abies Une 
Dallas TX 75229 
(214) 243-2272 

SUBSCRIPTIONS. Individual subscription rates 
are $50.00 per year (12 issues) in the U.S. and 
Puerto Rico, $70.00 per year in all other countries; 
$95.00 for 2 years in the U.S. and Puerto Rico, 
$135.00 in all other countries; and $140.00 for 
3 years in the U.S. and Puerto Rico, $200.00 in 
all other countries (add $84.00 per year for air 
mail). Annual organizational subscriptions are 
offered to members of associations according to 
their membership enrollment as follows: 101-500 
members— $5.00, 501-1,500 members— $4.50, 
1,501-2,500 members— $4.25, 2,501-5,000 
members— $4.00, 5,001-10,000 members— $3.00, 
and over 10,000 members— $2.00. Singles copies, 
when available, cost $5.00; add $7.00 air mail 
postage to foreign countries overseas. 

CHANGE OF ADDRESS. Six weeks notice is 
required to effect a change of address. Note your 
subscription number (from the mailing label), your 
name, and both old and new addresses, included 
zip codes. Please note your subscription number 
on the envelope. Copies will not be replaced 
without charge unless a request is received within 
60 days of the mailing in the U.S. or within 90 
days in other countries. 

ADVERTISING: 

RATES AND MEDIA KITS 

Aries Advertising Representatives 

Saul Homik 

Todd Poole 

Sandy Getterman 

12 Court St. 

Freehold NJ 07728 

(201) 462-7422 or 972-1911 

ADVERTISING. Display advertising for the 
Journal should be arranged with the advertising 
representatives. Respiratory Care does not 
publish a classified advertising column. 



CONTENTS, 



Continued 



March 1991 
Volume 36, Number 3 



BOOKS, FILMS, TAPES, & SOFTWARE 

229 The Asthma Resources Directory, by Carol Rudoff MA 
reviewed by Gretchen Lawrence — Dallas, Texas 

LETTERS 

231 PCIRV: Panacea or Auto-PEEP?— A Response Based on Clinical 
Experience 

by Edward Abraham, Gary Yoshihara, and John Wright— Los Angeles, 
California; with response by Robert M Kacmarek and Dean Hess — 
Boston, Massachusetts, and York, Pennsylvania 

CORRECTION 

177 Correction to Bear Medical Response to Excessive Airway Pressures 

during Accidental Disconnection from a Mechanical Ventilator (Respir 
Care 1991;36:132-133) 

ABSTRACTS 

150 Summaries of Pertinent Articles in Other Journals 

CALENDAR OF EVENTS 

234 Meeting Dates, Locations, Themes 
NOTICES 

233 Examination Dates, Notices, Prizes 
CALL FOR ABSTRACTS 

235 1991 Call for Open Forum Abstracts 
INFORMATION FOR AUTHORS 

237 Instructions for Authors and Typists 

INDEXES 

240 Authors in This Issue 
240 Advertisers in This Issue 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



149 



Abstracts 



Summaries of Pertinent Articles in Other Journals 



Reviews and Statements to Note 

Longitudinal Designs and their Statistical Analysis in Pediatric 
Pulmonary Research (editorial) — RW Helms. Pediatr Pulmonol 
1990;9:69. 

State of the Art: Smoking and Smoking Cessation (review) — 
EB Fisher Jr, D Haire-Joshu, GD Morgan, H Rehberg, K Rest. Am 
Rev Respir Dis 1990; 142:702 

Medical-Legal Definition of Occupational Asthma (special 
article)— DD Smith. Chest 1990;98:1007. 

Infection Control for Home Health (special commentary) — B 
Simmons, M Trusler, J Roccaforte, P Smith, R Scott. Infect Control 
Hosp Epidemiol 1990; 11:362. 

Scientific Basis of Pulmonary Rehabilitation: Position Paper of 
the American Association of Cardiovascular and Pulmonary 
Rehabilitation— AL Ries. J Cardiopulmonary Rehabil 1990;10:418. 

Diagnostic Standards and Classification of Tuberculosis 

(statement) — American Thoracic Society. Am Rev Respir Dis 
1990; 142:725. 



Pulmonary Function Testing Prior 
to Extubation in Infants with 
Respiratory Distress Syndrome — 

KA Veness-Meehan, S Richter, JM 
Davis. Pediatr Pul.l990;9:2. 

Pulmonary function testing was 
performed just prior to extubation on 
50 infants mechanically ventilated for 
treatment of respiratory distress 
syndrome. All infants were ready for 
extubation as defined by clinical 
criteria. Pulmonary mechanics and 
energetics were measured by a 
computerized technique that consists 
of a pneumotachometer to measure 
flowrates and an esophageal balloon 
and differential transducer to estimate 
transpulmonary pressure. Tidal 
volume, minute ventilation, dynamic 
lung compliance, pulmonary resist- 
ance, and resistive work of breathing 



were then calculated by high speed 
microcomputer processing. Suc- 
cessful extubation was defined 
as > 72 hours without respiratory 
decompensation requiring reinstitu- 
tion of ventilatory support. Thirty-six 
(72%) infants were successfully 
extubated and 14 (28%) infants failed 
extubation. Infants in the success and 
failure groups were matched for 
birthweight, gestational age, age at 
study, weight at study, weight at study 
relative to birthweight, use of nasal 
continuous positive airway pressure 
(CPAP), and methylxanthines. No 
statistically significant differences in 
pulmonary mechanics were seen 
between the two groups. Data sug- 
gests that successful withdrawal of 
mechanical ventilation may be related 
to multiple factors such as central 
inspiratory drive, diaphragmatic 



endurance, and chest-wall stability, in 
addition to improved lung mechanics. 
Pulmonary function testing criteria 
alone may not be useful in determin- 
ing optimal timing of extubation in 
premature infants. 

Respiratory Mucus pH in Tra- 
cheostomized Intensive Care Unit 
Patients: Effects of Colonization 
and Pneumonia — DR Kamad, DG 
Mhaisekar, KV Moralwar. Crit Care 
Med 1990; 18:699. 

Daily, we studied the effects of 
colonization and pneumonia on the 
pH of respiratory mucus in 23 
critically ill patients. Sixteen patients 
had tracheobronchial colonization, 
and 11 of these subsequently deve- 
loped pneumonia. Two other patients 



150 



RESPIRATORY CARE • MARCH '91 Vol. 36 No 3 



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ABSTRACTS 



developed pneumonia without prior 
colonization. For the 13 patients with 
pneumonia, there was a significantly 
greater decrease in pH below the 
value recorded on the day of intu- 
bation vs that for the 10 patients who 
did not have pneumonia. In the 1 1 
patients who developed initial colon- 
ization and then pneumonia, the pH 
did not change after colonization, but 
became acidic with the development 
of pneumonia. The pH returned to 
basal levels after recovery from 
pneumonia. We tested the pH value 
to differentiate between colonization 
and infection in these intubated 
critically ill patients. A decrease in 
pH 2= 0.2 below the pH value on the 
day of intubation could ' predict the 
presence of pneumonia with a positive 
predictive value of 90%. This 
decrease in pH occurred before or on 
the same day as the development of 
radiologically detectable pneumonia 
in most cases. Daily monitoring of 
the pH of tracheal mucus may be of 
value in critically ill intubated 
patients. 

Role of Molecular Diffusion in 
Conventional and High Frequency 
Ventilation— RA Klocke, AR Saltz- 
man, BJB Grant, AT Aquilina, S 
Zhang. Am Rev Respir Dis 
1990; 142:802. 

The influence of molecular diffusion 
on gas-mixing during conventional 
mechanical ventilation (CMV) and 
high frequency ventilation (HFV) was 
studied by observing the wash-in of 
six poorly soluble, inert gases in 
arterial blood. Anesthetized dogs 
were ventilated either with CMV or 
HFV. Following a step change in 
inspired gas composition, the increase 
in arterial concentrations of hydrogen, 
helium, methane, ethane, isobutane, 
and sulfur hexafluoride was deter- 
mined by gas chromatography. The 
relative gas diffusivities encompassed 
a range of almost one order of 



magnitude. Propane, present in 
inspired gas during both the control 
and wash-in phases, served as an 
internal reference for calculation of 
blood tracer concentrations. The 
wash-in of all six inert gases followed 
a single exponential time course 
during both CMV and HFV. The rate 
of wash-in of each gas decreased with 
increasing molecular weight (MW). 
The relationship of rate constants to 
a measure of relative diffusivity 
(MW-o-5) was significantly different 
than zero for both types of ventilation. 
The slope of this relationship was 
three times larger for CMV than HFV, 
indicating that molecular diffusion 
has a greater role in gas mixing during 
ventilation with large tidal volumes. 
Diffusion has a minor role in gas 
mixing during high frequency venti- 
lation with small tidal volumes. 
Demonstration of the presence of gas 
separation secondary to molecular 
diffusion during HFV is enhanced by 
measuring wash-in, rather than wash- 
out, of inert gases because gas 
separation is likely to be obscured as 
exhaled gases pass through the well- 
mixed central airways during gas 
wash-out. 



Oxygen Supplementation during 
Exercise in Cystic Fibrosis — PA 

Nixon, DM Orenstein, SE Curtis, EA 
Ross. Am Rev Respir Dis 
1990; 142:807. 

Fourteen female and 22 male patients 
with cystic fibrosis (CF), 8 to 29 years 
of age, performed two progressive 
exercise tests to exhaustion on a cycle 
ergometer, breathing normoxic air 
(21% O2) for one test, and hyperoxic 
air (30% O2) for the other test. The 
order of gas administration was 
randomized. Minute ventilation (Ve)- 
oxygen uptake (VO2), end-tidal CO2 
tension (PgtCO )' work rate, oxyhe- 
moglobin saturation (SaOj), and heart 
rate (HR) were measured throughout 
the tests. The Sa02 of 1 1 patients at 



peak exercise was 90% or less ("Low 
Sat" group). The SgOj of 23 patients 
remained above 90% throughout the 
exercise ("High Sat" group). Hype- 
roxic air minimized desaturation 
during exercise in the Low Sat group 
to 2 ± 2% compared to a decrease of 
10 ±5% with normoxic air. The 
decrease in saturation was not signif- 
icant for the High Sat group (1 ± 1% 
for both 2 1 % and 30% O2). Peak work 
rate and VO2 did not differ signif- 
icantly between normoxic and hype- 
roxic conditions. However, Vg and 
HR at peak exercise tended to be 
lower, and Petc02 was higher during 
peak exercise with 30% O2 than 21% 
O2 for both groups. During submax- 
imal exercise, O2 desaturation was 
diminished and HR was significantly 
lower with supplemental O2, specif- 
ically in the Low Sat group. Vg was 
significantly lower for both groups 
during submaximal exercise with 
hyperoxic air. The results suggest that 
O2 supplementation minimizes O2 
desaturation and enables patients with 
CF to exercise with reduced venti- 
latory and cardiovascular work. 

Efficacy of Positive vs Negative 
Pressure Ventilation in Unloading 
the Respiratory Muscles — MJ Bel- 
man, GW Soo Hoo, JH Kuei, R 
Shadmehr. Chest 1990;98:850. 



We compared the efficacy of positive 
pressure ventilation (PPV) vs nega- 
tive pressure ventilation (NPV) in 
providing ventilatory muscle rest for 
5 normal subjects and 6 patients with 
chronic obstructive pulmonary dis- 
ease (COPD). All participants under- 
went measurement of transdia- 
phragmatic pressure (Pji), pressure 
time integral of the diaphragm (PTI), 
integrated diaphragmatic electromyo- 
gram (iEMG), minute ventilation Vg, 
tidal volume (Vj), and end-tidal CO2 
(etC02) during 15 minutes of PPV 
and NPV. For each subject, ventilator 



RESPIRATORY CARE • MARCH. '91 Vol. 36 No 3 



153 



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ABSTRACTS 



adjustments were made to obtain Vg 
similar to levels measured during 
quiet breathing (QB). We found that 
the iEMG, Pji, PTI, and average 
coefficient of variation of the tidal 
volume (CV-Vj) were consistently 
lower during PPV as compared with 
NPV (p = 0.01). The iEMG normal- 
ized for Ve and Vj was also signif- 
icantly lower during PPV (p = 0.01). 
During PPV, subjects were mildly 
hyperventilated (lower etC02 and 
higher Vg) compared with QB and 
NPV, but no significant correlation 
was noted between the change in 
etC02 and the change in iEMG. The 
change in PTI was significantly 
correlated with the change in iEMG 
(p = 0.01). We conclude that in the 
short term, PPV is more effective than 
NPV in reducing diaphragmatic 
activity. Positive pressure ventilation 
may be the preferred method of 
assisted ventilation in future studies 
of ventilatory muscle rest therapy. 

Surfactant Replacement Therapy 
in Respiratory Distress Syndrome: 
Meta-Analysis of Clinical Trials of 
Single-Dose Surfactant Extracts — 

HM Hennes, MB Lee, AA Rimm, DL 
Shapiro. Am J Dis Child 
1991;145:102. 

Replacement therapy with surfactant 
extracts in premature infants with 
respiratory distress syndrome has 
been evaluated in several clinical 
trials. The results of individual trials 
do not provide conclusive evidence 
that administration of a single dose 
of surfactant improves morbidity or 
mortality. Meta-analysis is a statis- 
tical method to combine the results 
of such clinical trials, and combined 
analysis provides a means to over- 
come the problem of not being able 
to detect significant small differences 
in individual trials due to these small 
sample sizes. Seven clinical trials 
(277 patients treated with nonhuman 
surfactant extract and 263 controls) 
met the criteria for analysis; five 



outcome measurements (mortality, 
patent ductus arteriosus, pneumo- 
thorax, intraventricular hemorrhage, 
and bronchopulmonary dysplasia) 
were selected to estimate the treat- 
ment effect. The meta-analysis 
showed that a single dose of surfactant 
administered before the first breath 
or within 15 hours of birth signifi- 
cantly decreased the mortality rate 
(95% confidence interval = —0.19 
to — 0.03) and the risk of developing 
pneumothorax (95% confidence inter- 
val = -0.28 to -0.14) in infants 
with respiratory distress syndrome. 
Further clinical trials are needed to 
evaluate other aspects of surfactant 
replacement therapy in premature 
infants because inconsistent results 
were observed among the seven 
analyzed studies. 

Circadian Basis of the Late Asth- 
matic Response — AA Mohiuddin, 
RJ Martin. Am Rev Respir Dis 
1990:142:1153. 

The late asthmatic response (LAR) to 
an allergen challenge has a marked 
impact on lung function in the patient 
with asthma. Virtually all studies on 
the LAR have been done during the 
daytime. This study evaluated the 
LAR as a function of the time of day 
an inhaled allergen challenge was 
performed. An allergen challenge 
given in the morning produced a LAR 
in 4 of 10 subjects, while the same 
challenge in the evening caused a 
LAR in 9 of 10 (p < 0.05). The time 
to onset of the LAR following the 
morning and evening challenges was 
9.4 ± 2.0 h versus 3. 1 ± 0.3 h, respec- 
tively (p<0.05). The maximal 
decrease in FEV, for the LAR was 
32.8 ± 5.6% for the morning chal- 
lenge versus 43.0 ±3.1% in the 
evening (p < 0.05). Additionally, the 
bronchial responsiveness to methach- 
oline was significantly greater at 24 
h following evening allergen chal- 
lenge than after the morning 



(p<0.05) challenge. Thus, it is 
important to take into account the time 
of day a patient is exposed to an 
allergen in regard to the development 
of the LAR. 

Design and Validation of an Indi- 
cator Gas Injector for Multiple Gas 
Washout Tests in Mechanically 
Ventilated Patients — PEM Huygen, 
BWA Feenstra, WPJ Holland, C Ince, 
H Stam, HA Bruining. Crit Care Med 
1990;18:754. 

A device to produce a stepwise 
indicator-gas-fraction variation to 
initiate a washout test in mechanically 
ventilated patients is described. The 
device, which can be used in con- 
junction with the commonly used 
Siemens-Elema series 900 ventila- 
tors, is based on simple, off-the-shelf 
technology. It features the simultane- 
ous use of two indicator gases (so that 
the influence of diffusion processes 
in the gas exchange to the patient can 
be measured) and maintains a nearly 
constant Fjo^ during a washout 
procedure. With this indicator gas 
injector, the transition time of the 
indicator gas fraction at the beginning 
of a washout proved to be short 
enough to detect ventilation inho- 
mogeneity by visual inspection of the 
washout curves. Functional residual 
capacity measurements using this 
device are presented on a test lung 
with known volume, on healthy 
volunteers, and on critically ill 
patients. 

Bronchodilator Response to Iprat- 
ropium Bromide in Infants with 
Bronchopulmonary Dysplasia — KL 

Brundage, KG Mohsini, AB Froese, 
JT Fisher. Am Rev Respir Dis 
1990; 142: 1137. 

Although the muscarinic antagonist 
ipratropium bromide is used clinically 
as a bronchodilator in infants venti- 
lated because of bronchopulmonary 
dysplasia (BPD), no studies have 
compared the response or efficacy of 



RESPIRATORY CARE • MARCH '91 Vol. 36 No 3 



157 




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ABSTRACTS 



different dosages or its effectiveness 
in combination with (3-adrenergic 
agonists. We measured the response 
of respiratory system mechanics in 10 
ventilated infants (25 ± 2 days of age) 
to 75, 125, and 175 |xg ipratropium 
bromide (IB), 125 jig IB plus 0.04 
mg salbutamol (SAL), 175 \i.g IB plus 
0.04 mg SAL, and saline vehicle, 
delivered via nebulizer into the 
ventilator circuit. Respiratory system 
resistance (Rfs) and compliance (Cjs) 
were measured by the passive flow- 
volume technique. R^^ and Crs were 
measured before and at 1 to 2 h and 
at 4 h after delivery of the five drug 
dosages or saline. All six studies were 
completed within a 72-h period. 
Saline had no significant effect on 
mechanics. Significant responses to 
ipratropium alone were seen only 
after 175 |xg where Rrs decreased 
20 ± 3% (SEM) (p < 0.05) at 1 to 2 
h and 16 ± 5% (p < 0.05) at 4 h. After 
125 (xg IB + SAL and 175 jig 
IB + SAL, Rrs was significantly 
decreased both at 1 to 2 h and at 4 
h, and Crs was significantly increased 
20 ± 6% and 20 ± 6% and 20 ± 4%, 
respectively, at 1 to 2 h. The greatest 
decrease in Rrs (26 ± 6%) was seen 
1 to 2 h after 175 jjig IB + SAL. We 
conclude that muscarinic receptors 
contribute to the increased bronchom- 
otor tone of infants with BPD and 
that a combined dose of 175 fig IB 
and SAL should be used with this 
delivery system to ensure that the 
most effective and long-lasting bron- 
chodilation is obtained in the majority 
of premature infants. 

Metered Dose Inhaler Aerosol 
Characteristics Are Affected by the 
Endotracheal Tube Actuator/ 
Adapter Used — MJ Bishop, RP 
Larson, DL Buschman. Anesthesiol- 
ogy 1990;73:1263. 

The authors studied the particle size 
of aerosols of metaproterenol pro- 
duced by three different actuators 
designed for use in patients with 



endotracheal tubes in place. These 
were compared with the metaprote- 
renol aerosol produced by the actuator 
(provided by Boehringer-Ingelheim 
[BI]) that was supplied by the 
manufacturer for use in patients 
whose tracheas are not intubated. The 
volume of particles in the respiratory 
size range (1.0-5.1 |xm) delivered to 
the end of the endotracheal tube were 
measured using adapters designed by 
Intec (IT), Instrumentation Industries 
(II), and Monaghan (MAIS). Particle 
numbers were measured using a 
CSAS 100 scattering-aerosol laser 
spectrometer, and volumes were 
calculated by assuming the particles 
were spheres. The authors found that 
the volume of particles in the respi- 
ratory range with the IT, II, and MAIS 
adapters plus endotracheal tube were 
11,31, and 66%, respectively, of the 
volume produced in the respiratory 
range by the BI. When particles likely 
to impact before reaching the lower 
airways (>5 jim) were measured, 
almost none was produced by the 
adapters plus endotracheal tube, 
whereas the majority of drug volume 
in the BI aerosol was in the > 5 iJim 
range. It was concluded that the 
aerosol produced by different actu- 
ators differ from each other, that all 
three produced less drug in the 
respiratory range than was produced 
by the manufacturer-supplied actua- 
tor, and that large particles are 
effectively removed by the adapter 
plus endotracheal tube. 



Things To Remember: 

Take Advanta^ of the Earh Deadline 
for Open Forum— M arch 20. Abstracts 
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notified b\ April 26 — to allow revision 
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Original 
Contributions 

Evaluation of Ten Manual Resuscitators across an 
Operational Temperature Range of -18°C to 50°C 

Thomas A Barnes EdD RRT and Deborah L Stockwell 



Because of the temperature extremes encountered during emergency resuscitation 
and transport in the field, we sought to evaluate the performance and safety of 
10 adult resuscitators (5 permanent units: Hope 4, Laerdal, Lifesaver, Mark 3, 
and PMR; and 5 disposable units: BagEasy, Code Blue, CPR Bag, DMR, and SPUR) 
across an operational temperature range of -18°C to 50°C. METHOD: We tested 
the devices against the American Society for Testing and Materials (ASTM) Standard 
F-920 and the International Organization for Standardization (ISO) Standard 8382. 
We tested each resuscitator by using a lung model, the Bio-Tek VT-1 Ventilator 
Tester. RESULTS: All of the resuscitators met the ventilation requirements for 
Vx and f (600 mL x 20) and I:E < 1:1 except the SPUR at -18°C. Standards ASTM 
F-920 and ISO 8382 specify a fractional delivered oxygen concentration (Fdoj) 
of > 0.85 with attachments and > 0.40 without attachments at oxygen flow of 15 
L/min and V^ of 7.2 L/min (600 mL x 12). Nine resuscitators met Standards ASTM 
F-920 and ISO 8382 for Fdo^ with attachments at 21°C and 50°C, but only 3 
units (Code Blue, DMR, and PMR) passed at -18°C. At 2rC, the Hope 4 had 
an FDO2 of 0-77 ± 0.03, which was significantly lower (p < 0.001) than that of 
the other 9 resuscitators, all of which were ^ 0.93. Nine resuscitators met the FDO2 
standard without attachments. All 10 resuscitators passed the tests for valve function 
after contamination with simulated vomitus (at an oxygen flow of 30 L/min) and 
for backward leakage. At the ventilation pattern recommended by the American 
Heart Association (AHA) (800 mL x 12) the PMR's mean FdOj dropped to 
0.86 ± 0.03 because of air leaking into the bag where it attaches to the patient- 
valve assembly. All 10 resuscitators passed the test for mechanical shock at 21°C 
and 50°C, but 3 units failed at -18°C. CONCLUSION: We conclude that only 
the Code Blue and DMR meet the ASTM and ISO standards for operator-powered 
adult resuscitators across the operational temperature range of-18°C to 50°C. (Respir 
Care 1991;36:161-172.) 



Dr Barnes is Director of Clinical Education and Associate 
Professor of Respiratory Therapy, College of Pharmacy and 
Allied Health Professions, Northeastern University; and Ms 
Stockwell is a Respiratory Therapist, Beth Israel Hospital — 
Boston, Massachusetts. 

This study was completed at Northeastern University, Boston, 
Massachusetts; and the U.S. Army Research and Development 
Center, Natick, Massachusetts. Neither of the authors has a 
financial interest in any of the products tested. 

Dr Barnes and Ms Stockwell presented some of the material 
in this paper at the Respiratory Care Open Forum during 
the 1990 A ARC Annual Meeting in New Orleans, Louisiana. 

Reprints: Thomas A Barnes EdD RRT, College of Pharmacy 
and Allied Health Professions, Northeastem University, Boston 
MA 021 15. 



Introduction 

Manual resuscitators are used widely by hospital 
and emergency medical personnel.'-^ These bag- 
valve devices, whether disposable or permanent, 
should meet a series of minimum performance and 
safety specifications developed by the American 
Society for Testing and Materials (ASTM) and the 
International Organization for Standardization 
(ISO). 3'' During emergency, transport, or main- 
tenance ventilation, it is imperative that bag-valve 
units perform adequately to optimize patient 
oxygenation and ventilation. With the introduction 
of disposable manual resuscitators in recent years, 
health care providers with various degrees of 
training and experience have more options available 
to them when selecting bag-valve devices. 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



161 



MANUAL RESUSCITATOR PERFORMANCE FROM -18°C to 50°C 



Abbreviations Used in this Paper 

FDO2 — Fractional oxygen concentration 

f — Ventilatory rate 

I:E — Inspiratory-expiratory time ratio 

PaCOi — Arterial carbon dioxide tension 

PEEP — Positive end-expiratory pressure 

Vg — Minute volume 

Vj — Tidal volume 

A Guide to the Use of SI in this Paper* 

The SI unit for compliance is liters/ kilopascal (L/kPa). 
(L/cm H2O) (10.20) = L/kPa. 



The SI unit for resistance is the kilopascal (kPa ' s ' 
(cm H2O • s ■ L-i) (0.098 06) = kPa ■ s ■ L"'. 



L-'.). 



*For further information on SI (le Systeme International 
d'Unites), see Respir Care 1988;33:861-873 (October 
1988) and Respir Care 1989;34:145 (February 1989— 
Correction). 



According to the manufacturers, disposable bag- 
valve devices do offer the advantages of reduced 
cross-contamination and lower cost. However, 
recent reports by the Emergency Care Research 
Institute (ECRI)'' and other investigators (personal 
communication, D Theron Van Hooser, 1990) 
suggest that disposable bag-valve devices perform 
poorly at extremely cold temperatures. 

When ventilation with manual resuscitators is 
initiated, many variables may alter performance both 
in the field and in the clinical setting. Varying hand 
size and technique (one-hand vs two-hand venti- 
lation) has been shown to significantly affect the 
tidal volume that can be delivered by adult bag- 
valve units.^'^ It has also been reported by several 
investigators that ventilation pattern, resuscitator 
design, oxygen flow, and operator technique affect 
delivered oxygen concentration (Fdo2)-*"'^ ^^ 
found only one study,'' however, that reported on 
resuscitator performance at the extremely cold 
(-18°C) or hot (50°C) operating temperatures 
specified by the ASTM and ISO standards. In this 
report of 8 disposable manual resuscitators, the 
ECRI recommended not using the Ambu SPUR at 
-5°C because the cycling rate was reduced to 8 
compressions/min. 



Temperatures of « 0°F (^ -18°C) were 
recorded by more than ten weather stations in each 
of 42 states of the USA during 1988, and 
temperatures of 3= 113°F (^ 45°C) were recorded 
in two states (Arizona and California). '^ We were 
particularly interested in resuscitator performance 
at the temperature extremes encountered by 
firefighters, emergency medical technicians, police, 
ski patrol, and medics of the armed forces stationed 
world-wide. First-responder personnel must often 
store rescue equipment in unheated garages or in 
outside compartments or trunks of their vehicles. 
Thus, it would be reasonable to assume that 
resuscitators are not always stored and utilized under 
ideal room temperature conditions of 21°C. To 
evaluate resuscitator performance across the 
operating temperature range of -18°C to 50°C 
specified by the ASTM and ISO standards, we 
investigated 5 permanent units: Hope 4, Laerdal, 
Lifesaver, Mark 3, and PMR; and 5 disposable units: 
BagEasy, Code Blue, CPR Bag, DMR, and SPUR 
(Figs. 1-4).* 

Materials and Methods 

We investigated all the resuscitators at 70°F 
(21°C) for (1) Fdo2 with oxygen reservoir attached. 




Fig. 1 . Two adult manual resuscitators tested. A-Mark 3 
(permanent), B-SPUR (disposable). (See Figs. 2, 3, & 4 
for the other resuscitators tested.) 



*Suppliers are identified in the Product Sources section at the 
end of the text. 



162 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



MANUAL RESUSCITATOR PERFORMANCE FROM -18°C to 50°C 




Fig. 2. Two adult manual resuscitators tested. A-DMR 
(Disposable), B-PMR (Permanent). (See Figs. 1, 3, & 4 
for the other resuscitators tested.) 




Fig. 3. Three permanent adult manual resuscitators 
tested. A-Laerdal, B-Hope 4, C-Lifesaver. (See Figs. 1, 
2, & 4 for the other resuscitators tested.) 




(2) Fdo2 without oxygen reservoir attached, (3) valve 
function in the presence of simulated vomitus, (4) 
valve function during high flow of 30 L/min, (5) 
backward leakage of exhaled gas, (6) tolerance of 
mechanical shock (wet and dry), (7) tidal volume 
capability, (8) cycle-rate capability, and (9) 
operation after water immersion. 

The resuscitators were also investigated at 0°F 
(-18°C) and 123°F (50°C) for (1) Fdo, with oxygen 
reservoir attached, (2) tidal volume capability, (3) 
cycle-rate capability, (4) valve function during high 
flow of 30 L/min, (5) valve function when wet with 
exhaled gas condensate (-18°C only), and (6) 
tolerance of mechanical shock. Four specifications 
tested at 21°C (Fdoj without oxygen reservoir, 
patient-valve function with vomitus, patient-valve 
backward leakage, and water immersion) were not 
evaluated at -18°C or 50°C due to limited time 
available in the environmental chamber. Patient- 
valve function when wet with condensate is not 
an ISO or ASTM specification and was not tested 
at 21°C or 50°C because we were only interested 
in the effect of ice formation. The relative humidity 
was maintained at 53% for tests at -18°C and at 
20% for tests at 50°C. Wind speed was < 3 mph 
during testing. The resuscitators were allowed to 
stabilize for a minimum of 4 hours at the ambient 
conditions used during testing. 

FDO2 

We evaluated the performance of each resusci- 
tator by means of the test apparatus shown in Figure 
5. A pressure-compensated Thorpe-tube flowmeter 
supplied oxygen to the resuscitator. The oxygen 



Fig. 4. Three disposable adult manual resuscitators 
tested. A-Code Blue, B-BagEasy, C-CPR Bag. (See Figs. 
1 , 2, & 3 for the other resuscitators tested.) 




Fig. 5. Test apparatus used to evaluate manual resus- 
citators. 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



163 



MANUAL RESUSCITATOR PERFORMANCE FROM -18°C to 50°C 



flowrate was verified before and after each test run 
with a Timeter Model RT-200 Calibration Analyzer. 
The resuscitator was manipulated to ventilate a Bio- 
Tek VT-1 Ventilator Tester. For tests at 21°C, a 
sampling probe from a Beckman OM-15 polaro- 
graphic oxygen analyzer was connected to the gas 
port of the VT-1 to measure Fdot A 3-point 
calibration of the oxygen monitor was performed 
immediately prior to testing each resuscitator with 
test gases having oxygen concentrations of 0.21, 
0.80, and 1.00 to assure linearity across the entire 
scale. Each resuscitator was tested at 21°C for FDO2 
at Ventilation Patterns 1, 2, and 3 with oxygen flow 
of 15 L/min to the unit. For each run, the VT-1 
was ventilated until the FDO2 was constant (3 to 4 
min). Five runs at 2 1 °C were made for each resuscitator 
at each ventilation pattern (Table 1 ). 

Because of the slow response time and inaccuracy 
of the OM-15 polarographic sensor at -18°C and 
50°C, we used an Ametek S-3A/I oxygen analyzer 
system with a ceramic zirconium oxide cell heated 
to 650°C for FDO2 measurements made in the 
environmental chambers at these extreme temper- 
atures. The S-3A/I system had a response time of 
100 ms to 90% of final reading and 0.01% resolution 
and accuracy. A 2-point calibration of the S-3A/I 
oxygen analyzer was performed with test gases having 
an oxygen concentration of 0.2 1 and 1 .00. Gas was 
pumf)ed from the gas port of the VT-1 at 100 mL/ 
min to the oxygen analyzer system, which was located 
outside the environmental chamber. Only Ventilation 
Patterns 1 and 3 were used for tests of FDO2 at -18°C 
and 50°C because of the limited time available in 
the environmental chambers. 

Ventilation 

Cycle Rate and Tidal Volume. At 21°C, the cycle- 
rate and tidal volume requirements were tested using 
Ventilation Patterns 1 , 2, and 3 and an oxygen flow 
of 15 L/min (Table 1). At -18°C and 50°C, these 

Table 1 . Ventilation Patterns Used To Test Resuscitators 



Ventilation 
Pattern 



Tidal 

Volume (Vj) 

(mL) 



Ventilatory Minute 

Rate (f) Volume (\fe) 
(cycles/min) (L) 



600 
800 
600 



12 
12 
20 



7.2 

9.6 

12.0 



requirements were tested using Ventilation Patterns 
1 and 3 and an oxygen flow of 15 L/min. Each 
resuscitator was evaluated against ASTM and ISO 
specifications for tidal volume and cycle rate by 
ventilating the VT- 1 for 4 minutes — configured for 
adult units. 

The VT-1 was set at a compliance of 0.02 L/ 
cm H2O [0.20 L/kPa] and a resistance of 20 cm 
H2O ■ s • L^' [2 kPa • s • L-'] as specified in the 
ASTM and ISO standards. The precision of the VT- 
1 display of tidal volume (Vj) was verified with a 
calibrated super syringe, and the display of ventilatory 
rate (f) was confirmed with a chronometer. A Wright 
Model L-D panel-mounted respirometer was placed 
between the VT-1 and the resuscitator to provide an 
approximate indication of the delivered V^, which 
was monitored breath-by-breath by the VT-1 status 
display. The primary control of the ventilation 
pattern was the VT-1 display, which indicated the 
Vj, f, minute volume (V^), and inspiratory- 
expiratory time ratio (I:E). We ventilated the VT- 1 
by squeezing the resuscitator bag while observing 
the Vj displayed by the VT-1, and using the 
chronometer to determine f. When the desired Vj 
was reached, the bag was released and allowed to 
fill without restriction. Immediately after the bag 
had been released, the VT-1 status display was 
checked to confirm that the Vj, f, and Vg were 
correct. We were able to control the ventilatory 
pattern by making small adjustments in the Vx and 
f based on immediate feedback from the VT-I 
display. 

For extreme temperature testing in the environ- 
mental chamber, the RS232 data-output port of the 
VT-1 was connected by cable to a Macintosh IIX 
computer located at a window outside the chamber. 
The data were displayed on a two-page Apple 
monitor that was easily read from inside the 
chamber. A Bio-Tek thermal printer was located 
outside the chamber and connected by cable to the 
VT- 1 . A Vent-Aid Training Test Lung (TTL) was 
used to evaluate tidal volume and cycle-rate 
specifications following the drop and ice-formation 
tests in the environmental chambers because the 
VT-1 was in continuous use for the FDO2 test. The 
TTL was also used to evaluate ventilation 
specifications whenever the patient valve became 
wet during testing (ie, from vomitus, water 
immersion, ice formation). 



164 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



MANUAL RESUSCITATOR PERFORMANCE FROM -18°C to 50°C 



Valve Performance 

High Supplemental Flows. To verify that the 
patient valve would not lock at high flow, oxygen 
flow to each resuscitator was set at 30 L/min, and 
the VT-1 was ventilated with Patterns 1 and 3. The 
flow of 30 L/min was verified with a Timeter Model 
RT-200 Calibration Analyzer. 

Patient- Valve Backward Leakage. The potential 
for rebreathing was tested by connecting the 
resuscitator (without attachments or oxygen flow) 
to a 2-L anesthesia bag supplied with an oxygen 
flow of 15 L/min. The resuscitator was cycled at 
f 30/min for 3 minutes, and then the oxygen 
concentration in the resuscitator bag was measured 
with a Beckman OM-15 Oxygen Monitor. The 
ASTM backward leak requirement limits the 
increase of Fq, in the resuscitator bag to less than 
10 percentage points (ie, to Fq^ < 0.31). 

Valve Function after Contamination by Vomitus. 

To evaluate this requirement, we poured 175 mL 
of simulated vomitus into the patient-connection 
port while cycling the resuscitator at f 12/min for 
30 seconds. Vomitus was simulated by a mixture 
of two parts of baby food (Gerber Toddler Meal, 
Beef with Vegetables) and one part water. The 
patient valve was cleared of vomitus by squeezing 
the bag briskly and shaking any remaining 
obstructing material out of the exhalation port and 
patient-connection port. Immediately following 
removal of the vomitus from the patient-valve 
assembly, performance was assessed by using the 
resuscitator to ventilate the TTL with Ventilation 
Patterns 1 and 3. The TTL was configured with 
the same compliance and resistance setting as the 
VT-1. 

Valve Function at Extreme Cold Temperature 

(-18°C). A spontaneously breathing healthy volunteer 
was ventilated with each bag-valve-mask device for 
10 min at -18°C. Ventilation was accomplished with 
communication and cooperation between the exper- 
imenter who squeezed the bag and the subject who 
held the mask tightly to his face. The patient valve 
was checked for ice formation and normal function 
during the 10-min trial when exhaled gas with 100% 



relative humidity (at body temperature) passed through 
the exhalation port. Following manual ventilation 
of the subject for 10 min, each resuscitator was 
set aside with the patient-valve assembly wet from 
exhaled gas condensate. The wet valves were 
checked for valve function after 5 min and 30 min 
by ventilating the TTL test lung with Ventilation 
Patterns 1 and 3. The TTL was configured with 
the same compliance and resistance setting as the 
VT-1. 

Mechanical Shock (Drop Test) 

Each resuscitator was dropped 5 times from a 
height of 1 meter onto a concrete floor at 21°C 
and onto a heavy steel plate inside the environmental 
chamber at -18°C and 50°C. The unit was dropped 
in a worst-case mode so that it landed on the patient- 
valve and gas-intake-valve assemblies. The units 
were dropped five times to assure that mechanical 
shock was delivered to both patient-valve and gas- 
intake-valve assemblies at a minimum of two impact 
angles. Following the shock test, we inspected the 
resuscitator for damage and checked its performance 
by ventilating the TTL with Ventilation Patterns 
1 and 3. 

Immersion in Water 

Each resuscitator was arranged in its ready-for- 
use configuration and dropped from a height of 1 
meter into a water reservoir. After 10 seconds, the 
resuscitator was removed from the reservoir and 
shaken for not more than 20 seconds to remove 
water. Once free of water, the resuscitator was tested 
for normal function by ventilating the TTL with 
Ventilation Patterns 1 and 3. 

The effect of resuscitator design, ventilation 
pattern, and temperature on FDO2 ^^^ evaluated by 
three-way analysis of variance. A paired t test was 
used to determine the independent effect of 
temperature or ventilation pattern on Fdot The 
effect of resuscitator design on Fdot was evaluated 
by one-way analysis of variance; p < 0.05 was 
considered significant. All statistical tests were 
performed with Exstatix version 1 .0. 1 software. 

Results 

Tables 2 and 3 list the mean (SD) Fdo-> values 
for the 10 resuscitators we studied. Tables 4 and 
5 list the resuscitators' pass/fail results for the ISO 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



165 



MANUAL RESUSCITATOR PERFORMANCE FROM -18°C to 50°C 



Table 2. Fractional Oxygen Concentration Delivered by Ten Resuscitators at 21 °C 



With Reservoir Without Reservoir 



600x12* 800x12 600x20 600x12 



Permanent Resuscitators 

Mark 3 1.00 (O.OO)t 0.99(0.01) 1.00(0.00) 0.44(0.01) 

Lifesaver 1.00 (0.01) 0.99 (0.02) 1.00 (0.00) 0.47 (0.01) 

Laerdal 0.99 (0.00) 0.99 (0.00) 1.00 (0.00) 0.40 (0.01) 

PMR 0.98 (0.01) 0.86 (0.01) 0.88 (0.04) 0.35 (0.01) 

Hope 4 0.77 (0.03) 0.75 (0.04) 0.72 (0.02) 0.42 (0.02) 

Disposable Resuscitators 

BagEasyt 1.00 (0.00) 1.00 (0.00) 1.00 (0.00) 

Code Bluet 100 (0.00) 0.98 (0.00) 0.97 (0.01) 

DMRJ 0.97 (0.00) 0.89 (0.01) 0.91 (0.01) 

CPRBag 0.96 (0.00) 0.96 (0.01) 0.94 (0.02) 0.43 (0.02) 

SPUR* 0.93 (0.01) 0.95 (0.01) 0.96 (0.00) 



*Tidal volume (mL) x ventilatory rate (cycles/min). 

Compliance 0.020 L/cm H2O [0.20 L/kPa]. 

Resistance 20 cm H2O • s • L' [2 kPa • s ■ L"']- 

Oxygen flow 15 L/min. 
tMean (SD). 
|The reservoir is permanently attached. 



Table 3. Fractional Oxygen Concentration Delivered by Ten Resuscitators at - 18°C and 50°C 

-18°C(0°F) 50°C(123°F) 



600x12* 600x20 600x12 600x20 



Permanent Resuscitators 



PMR 


0.93 (0.01 )tt 


0.85(0.01)1 


0.94 (0.02)t 


0.95 (0.02)$ 


Mark 3 


0.83 (0.06)t 


0.82 (0.01)4: 


1.00(0.00) 


1.00(0.00) 


Lifesaver 


0.81 (0.02)t 


0.70 (0.02):!: 


0.99(0.01) 


0.99(0.01) 


Laerdal 


0.73 (0.03)t 


0.74 (0.03):!: 


1.00(0.00) 


1.00(0.00) 


Hope 4 


0.54 (0.02)t 


0.48(0.01):!: 


0.91 (0.02):!: 


0.89 (0.0 l)t 


Disposable Resuscitators 










Code Blue 


1.00(0.00) 


0.99 (0.02) 


0.97 (0.03) 


0.94 (O.OO)* 


DMR 


0.89 (0.0 l)t 


0.81 (0.02)1 


0.92(0.01):]: 


0.89 (0.03) 


BagEasy 


0.66 (0.02)t 


0.64 (0.03)t 


1.00(0.00) 


1.00(0.00) 


CPR Bag 


0.53 (0.01)1 


0.51 (0.01 )t 


1.00(0.00)1 


1.00(0.00)$ 


SPUR§ 


o.oot 


0.00:1: 


1.00(0.00):!: 


1.00(0.00)1 



*Tidal volume (mL) x ventilatory rate (cycles/min). 

Compliance 0.020 L/cm H2O [0.20 L/kPa]. 

Resistance 20 cm H2O ■ s ■ L"' [2 kPa ■ s • L"']- 

Oxygen flow 15 L/min. 
tMean (SD). 

^Significance level p < 0.01 when compared to 21°C. 
§Bag would not reinflate after first cycle at - 18°C. 



166 RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



MANUAL RESUSCITATOR PERFORMANCE FROM -18°C to 50°C 



Table 4. Performance of Ten Resuscitators against Nine Requirements of ASTM F-920 and ISO 8382 at 2I°C 



Fd02 



Valve Function 



Meclianical 
Shock 



Ventilation 



Resuscitator With Without With With Flow Backward Drop Test Water Vt= f= 

Tested Reservoir Reservoir Vomitus of 30 L/min Leakage 1 Meter Immersion 600ml 20/min 



BagEasy < 


» - • • 


Code Blue « 


» - • • 


CPR Bag « 


> • • • 


DMR t 


» - • • 


Hope 4 C 


3 • • • 


Laerdal < 


» • • • 


Lifesaver * 


» • • • 


Mark 3 < 


» • • • 


PMR < 


» O • • 


SPUR < 


9^9 w 



• Resuscitator met or exceeded standard. 
O Resuscitator did not meet standard. 



Table 5. Performance of Ten Resuscitators against Five Requirements of ASTM F-920 and ISO 8382 at - 18°C and 50°C 







Valve 


Mechanical 








Fd02 


Function 


Shock 




Ventilation 




With 


With Flow of 


Drop Test 


Vt = 


f = 


Resuscitator 


Reservoir 


30 L/min 


1 meter 


600 mL 


20/min 


Code Blue 


• / 


• • 


• • 


• / 


• / 


PMR 


• / 


• / 


• / 


• / 


• / 


DMR 


• / 


• / 


• / 


• / 


• / 


Mark 3 


o / 


• / 


• • 


• / 


• / 


Lifesaver 


o • 


• / 


• / 


• / 


• / 


Laerdal 


o • 


• / 


• / 


• / 


• • 


BagEasy 


o • 


• / 


• / 


• / 


• / 


Hope 4 


o • 


• / 


o / 


• / 


• / 


CPR Bag 


o • 


• / 


o / 


• / 


• / 


SPUR 


o • 


o • 


o / 


o • 


o / 



• Resuscitator met or exceeded standard at - 1 8°C. 
O Resuscitator did not meet standard at - 18°C. 
/ Resuscitator met or exceeded standard at 50°C. 
X Resuscitator did not meet standard at 50°C 



and ASTM requirements for resuscitator perfor- 
mance and safety. We found that resuscitator design 
significantly affects the FDO2 (P < 0.0001). The Fdoj 
of all the resuscitators, except the Code Blue, was 
significantly affected by extreme cold temperature 
(p < 0.01). Ventilation pattern significantly affected 
the FDO2 of the Hope 4, PMR, DMR, and SPUR 
at 21°C (p < 0.01) and the PMR, Lifesaver, Hope 



4, DMR, and CPR Bag at -18°C (p < 0.01); but 
ventilation pattern did not significantly affect the FDO2 
of any of the resuscitators at 50°C. The extreme hot 
ambient temperature of 50°C affected the Fdo^ 
performance of 6 resuscitators (p < 0.01). The FDO2 
of the SPUR, Hope 4, CPR Bag, and Laerdal was 
higher at 50°C than at 21°C; and the FD02 °^ ^^e 
DMR and PMR was lower at 50°C than at 21°C. 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



167 



MANUAL RESUSCITATOR PERFORMANCE FROM -18°C to 50°C 



All the resuscitators (except the SPUR) were 
successfully used to ventilate a spontaneously 
breathing subject for 10 min in the arctic chamber 
at -18°C. All the resuscitators that were tested for 
ice formation remained functional after being set aside 
for 5 min with patient valves that were wet with 
condensate from exhaled gas. Decreased Vj due to 
ice formation was encountered with two resuscitators 
set aside wet for 30 min. The SPUR could not be 
tested for ice formation because its bag would not 
expand after being squeezed once. 

Code Blue 

The Code Blue passed nine ASTM and ISO 
standards at 21°C. It was the only unit to deliver 
an Fdo2 of 1.00 at both -18°C and 21°C. The Code 
Blue passed all five ASTM and ISO specifications 
tested at -18°C and 50°C. 

PMR 

The PMR passed eight ASTM and ISO standards 
at 21°C, but failed the requirement for Fdoj without 
the oxygen reservoir attached. A significant drop 
in Fdo2 occurred at Ventilation Patterns 2 and 3 
at 21°C (p < 0.001) and at Ventilation Pattern 3 
at -18°C and 50°C (p < 0.05). The PMR passed 
all five ASTM and ISO specifications tested at 
-18°Cand50°C. 

DMR 

The DMR passed eight ASTM and ISO standards 
at 21°C. The requirement for FDO2 without the 
oxygen reservoir was not evaluated because the 
reservoir is permanently attached. A significant drop 
in FDO2 occurred at Ventilation Patterns 2 and 3 
at 21°C (p < 0.001) and Ventilation Pattern 3 when 
tested at -18°C and 50°C (p < 0.001). The DMR 
passed all five ASTM and ISO specifications tested 
at-18°Cand50°C. 

Mark 3 

The Mark 3 passed nine ASTM and ISO standards 
at 21°C but failed the Fdoj requirement at -18°C. 
The Mark 3 passed all "five ASTM and ISO 
specifications tested at 50°C. 



Lifesaver 

The Lifesaver passed nine ASTM and ISO 
standards at 21°C, but failed the FDO2 requirement 
at -1 8°C. A significant further drop in Fdot occurred 
at -18°C with Ventilation Pattern 3 (p < 0.001). 
The FDO2 '^•^ "o*^ '^^^ significantly with changes 
in the ventilation pattern at 21°C or 50°C. The 
Lifesaver failed the mechanical shock test at 50°C 
because the patient-valve assembly separated into 
three parts, and the gas-intake valve fell into the 
resuscitator bag when it was dropped from a height 
of 1 meter. 

Laerdal 

The Laerdal passed nine ASTM and ISO 
standards at 21°C, but failed the FDO2 requirement 
at -18°C. The Laerdal passed all five ASTM and 
ISO specifications tested at 50°C. 

BagEasy 

The BagEasy passed eight ASTM and ISO 
standards at 21°C. The requirement for FDO2 without 
the oxygen reservoir was not evaluated because the 
reservoir is permanently attached. The BagEasy failed 
the Fdot requirement at -1 8°C. During the mechanical 
shock test at -18°C, the PEEP adjustment screw broke 
off when the unit was dropped from a height of 1 
meter. The BagEasy passed all five ASTM and ISO 
specifications tested at 50°C. 

Hope 4 

The Hope 4 passed eight ASTM and ISO 
standards at 21°C, but failed the FDO2 requirement 
because it delivered an oxygen concentration of only 
0.77 at Ventilation Pattern 1. The Hope 4 also failed 
the FDO2 requirement at -18°C, delivering an FDO2 
of only 0.54. The mechanical shock test was failed 
at -18°C because the oxygen reservoir shattered 
into pieces when dropped from a height of 1 meter. 
The Hope 4 passed all five ASTM and ISO 
specifications tested at 50°C. The Fdot increased 
significantly from 0.77 at 21°C to 0.91 at 50°C 
(p < 0.001). 

CPR Bag 

The CPR Bag passed nine ASTM and ISO 
standards at 21°C. The resuscitator failed the FD02 
requirement at -1 8°C because it delivered an oxygen 



168 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



MANUAL RESUSCITATOR PERFORMANCE FROM -18°C to 50°C 



concentration of only 0.53 at Ventilation Pattern 
1. The mechanical shock test was failed at -18°C 
because the exhalation port where a PEEP device 
would be attached shattered when dropped from 
a height of 1 meter. The CPR Bag passed all five 
ASTM and ISO specifications tested at 50°C. The 
Fdo2 increased significantly from 0.96 at 21°C to 
1.00at50°C(p < 0.0001). 

SPUR 

The SPUR passed eight ASTM and ISO standards 
at 2I°C. The requirement for FD02 without the 
oxygen reservoir was not evaluated because the 
reservoir is permanently attached. The SPUR failed 
all five of the ASTM and ISO requirements at-18°C 
because the bag would not inflate after being 
squeezed only once. The SPUR passed all five 
ASTM and ISO specifications tested at 50°C. The 
FDO2 increased significantly from 0.93 at 21°C to 
1.00at50°C(p < 0.01). 

Discussion 

There were several clinically important differ- 
ences in performance and safety among the 
resuscitators tested. Only the Code Blue, DMR, and 
PMR passed the ASTM and ISO standards for FDO2 
at the cold end of the operational range (-18°C). 
The Hope 4 (with reservoir) and PMR (without 
reservoir) failed the FD02 requirement at 21°C. The 
SPUR failed five ASTM and ISO specifications at 
-18°C because it failed to inflate after being 
squeezed only once. The extreme cold (-18°C) 
caused the SPUR, CPR Bag, and Hope 4 to fail 
the shock tolerance test, and extreme heat (50°C) 
caused the Lifesaver to fail the shock test. 

Shock Test 

Shock tolerance is an important requirement for 
resuscitators because time lost to repair or replace 
a disabled resuscitator may be critical during 
emergency ventilation. The most likely accident would 
be dropping the resuscitator onto a hard floor during 
a resuscitation or transport. Shock tolerance is 
evaluated based on the premise that a resuscitator 
should be functional after being dropped from 1 meter, 
which is the height of an average hospital bed. 
Previously tested resuscitators have been reported to 
have clinically important problems with mechanical 
shock resistance at an ambient temperature of 2 1 °C.*'^ 



The ASTM and ISO standards for resuscitators specify 
an operational range of -18°C to 50°C. Cardiopul- 
monary resuscitation is provided by rescuers in 
conditions at the extreme ends of the operating range 
often with equipment that is also stored at the ambient 
temperature. 

All ten units passed the shock test at 2 1 °C. However, 
three units failed at -18°C: The SPUR failed to inflate 
after the bag was squeezed only once, the oxygen 
reservoir of the Hope 4 shattered into several pieces 
when dropped from 1 meter, and the patient connection 
of the CPR Bag separated from the patient-valve 
assembly when dropped. Although PEEP is not 
addressed by either the ASTM or ISO standards, loss 
of ability to attach a PEEP valve or to regulate an 
integral PEEP mechanism may be critical to 
maintenance of adequate oxygenation. When dropped 
at -18°C, the BagEasy resuscitator had the PEEP- 
regulating screw break off, negating adjustment of 
PEEP. 

The total collapse of the bag of the SPUR at 
-18°C is the most serious resuscitator failure we 
have encountered in over 12 years of testing bag- 
valve devices. The unit becomes immediately 
nonfunctional as a result of normal use at the cold 
end of the operating range. Emergency personnel 
may not be aware of the problem until attempting 
to use the device during a resuscitation because the 
bag maintains its shape until squeezed. 

The separation of the patient connection of the 
CPR Bag when dropped at -I8°C is a serious 
problem because the chances of a bag-valve device 
being subjected to rough treatment is greater in the 
field under extreme cold-temperature conditions. 
The loss of the Hope 4's oxygen reservoir when 
dropped at -18°C was of little consequence because 
the 10-mil plastic was as hard as glass, and the 
reservoir was not able to inflate. 

The only shock-test failure at 50°C occurred when 
the patient valve and gas-intake valve of the 
Lifesaver fell apart when dropped. If all the parts 
could be located, an experienced user could possibly 
reassemble the unit; however, an unacceptable delay 
in emergency ventilation would occur. Further, the 
average rescuer may not have the skill to identify 
the missing parts and assemble the unit — especially 
the gas-intake valve, which fell into the bag when 
it was dropped. We suspect that the heat caused 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



169 



MANUAL RESUSCITATOR PERFORMANCE FROM -18°C to 50°C 



the threaded parts to expand beyond the tolerance 
Hmit for the components to remain together. 

The water-immersion test is part of the ISO 
standard, but it is not required by the ASTM 
standard. The rationale for the ISO specification 
is that resuscitators are often used in areas where 
the device could be dropped into water during 
resuscitation.'* Not surprisingly, all the units floated 
when dropped in the water-immersion tank, and the 
small amount of water that entered the units was 
easily cleared. 

Fdoj 

Delivery of a minimum oxygen concentration of 
0.85 is often necessary for treatment of severely 
hypoxic patients during resuscitation. This concen- 
tration should be obtainable with oxygen 
flows ^15 L/min, because flows > 15 L/min 
exceed the normal calibration of standard adult 
flowmeters and could potentially lead to extremely 
high input flows and valve lockup. '"^ Previous 
studies have reported that interaction between 
resuscitator design and flowrate significantly affects 
Fdo2 ^^^ ^^^^ ^^'-^ factor independently affects 

The Hope 4 failed the Fdoj test at 21°C and -18°C 
because of the failure of the oxygen reservoir to inflate 
fully. The reservoir is manufactured of heavy 10-mil 
plastic that became extremely brittle and hard at -1 8°C 
and was stiff even at 21°C. The Hope 4 had an FDO2 
of only 0.54 at -18°C, which can be compared to 
its FDO2 of 0.42 without a reservoir at 21°C. The 
extremely low FDO2 of 0.11 at room temperature makes 
the Hope 4 unacceptable for use during normal hospital 
CPR. It should be noted that the Hope 4 passed the 
FDO2 requirement at 50°C because the heat made the 
oxygen reservoir soft and compliant and consequently 
fiiUy expandable. 

All the resuscitators that had a bag-type oxygen 
reservoir delivered an unacceptable FDO2 when 
tested at -18°C (Table 3). We believe this is the 
result of incomplete expansion of the oxygen 
reservoir due to the plastic becoming stiff and 
noncompliant at low temperatures. The combination 
of small reservoir volume and stiff plastic has 
previously been reported to affect the FDO2 
performance of resuscitators.*-^ In our study the three 
units that passed the FDO2 requirement at -18°C 



all had tube reservoirs. We suspect that the Mark 
3, Lifesaver, Laerdal, Hope 4, and CPR Bag might 
all have had a higher FDO2 ^^ -18°C if they had 
used a tube reservoir, similar to the type used by 
the Code Blue. 

The PMR had marginal FD02 performance at the 
ventilation patterns recommended by the AHA (800 
mL X 12) '5 and required by the ASTM and ISO 
specifications for ventilation (600 mL x 20).^'* We 
believe this was due to an air leak located where 
the bag attaches to the patient-valve assembly. This 
leak appears to occur only when a larger force is 
applied to the bag for delivering a 800-mL tidal 
volume or when the cycle rate is increased from 
12/min to 20/min (Table 2). Another cause of the 
problem may be that the volume capacity of the 
PMR and DMR reservoirs may be too small to 
accommodate a Vg above 7.2 L/min. Indeed, we 
have recently been notified by Puritan-Bennett that 
they plan to lengthen the oxygen reservoirs of the 
PMR and DMR to improve FDO2 capability. 

The PMR failed the FDO2 test that requires an 
FDO2 ^ 0.40 when an oxygen reservoir is not 
attached to the resuscitator, but we do not believe 
this is a clinically important problem. Resuscitators 
used to deliver a low FD02 ^^^ normally cycled 
at rates low enough to allow retarding of bag refill, 
which would easily increase the FDO2 of the PMR 
to over 0.40. '2 

Valve Performance 

A locked patient valve at high supplemental 
oxygen flow may cause excessive airway pres- 
sures.'"' The resuscitators should be capable of 
functioning normally at high flows of 30 L/min 
because the adjustment between 15 L/min and the 
30 L/min portion of the flood setting is small. The 
nonrebreathing valves of all units functioned well 
with high flow of 30 L/min at -18°C, 21°C, and 
50°C except those of the SPUR, which were 
nonfunctional at -18°C. The SPUR might have 
passed at -18°C if its bag had not collapsed. 

Because it is very important to provide adequate 
ventilation during resuscitation, bag-valve units 
should be capable of being cleared of vomitus within 
20 seconds. Clearing simulated vomitus from the 



170 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



MANUAL RESUSCITATOR PERFORMANCE FROM -18°C to 50°C 



patient valves was not a problem with the 
resuscitators tested, and all units were functional 
in less than 20 seconds. 

Exhaled water vapor condensing on the patient- 
valve assembly was a potential problem at the low 
end of the required operational temperature range. 
We found that at -18°C, the valve did not freeze 
after 10 min of bag-valve-mask ventilation of a 
volunteer. Further, the valve was still functional after 
being set aside wet with condensate for 5 min. Two 
of the units set aside wet for 30 min had enough 
ice to significantly lower the V-j- capability; however, 
we do not believe this is clinically important because 
it is unlikely that a bag-valve unit would be set 
aside wet for more than a few minutes during CPR 
or transport. 

Patient-valve backward leakage was not a 
problem with the 10 units tested at 21°C. Backward 
leakage was not tested at -18°C and 50°C because 
of the constraints of collecting data in the 
environmental chambers. However, this test should 
be done when possible because valve seating may 
be disrupted at low and high temperatures, and 
exhaled gas may leak back into the bag. Exposure 
to even low levels of inspired CO2 may lead to 
increased arterial CO2 tension (Paco2) ^"^ to 
decreased arterial pH.'^ 

Ventilation 

The ASTM and ISO tidal-volume requirement 
of 600 mL is important because it is the maximum 
volume that typically can be delivered with one- 
handed use of adult manual resuscitators at the 
compliances and resistances found in abnormal 
lungs.3'4-7 The frequency requirement of 20/min 
represents the upper limit typically used in adult 
resuscitation.''4i5 We found that the ventilation 
pattern recommended by the AHA (800 mL x 12) 
required a two-handed squeeze of the resuscitator 
bag at the compliances and resistances specified 
by the ASTM and ISO standards. 

Conclusions 

Of the 10 units tested, only the Code Blue and 
DMR met the ASTM and ISO standards for 
operator-powered adult resuscitators across the 



operational range of -18°C to 50°C (Tables 4 and 
5). We conclude that in extremely cold ambient 
conditions, manual resuscitators with tube-type 
oxygen reservoirs deliver a higher Fdot than that 
delivered by manual resuscitators with bag-type 
reservoirs, and the difference is large enough to 
be clinically important. We recommend that the 
SPUR not be used at -18°C because the bag fails 
to inflate after only one cycle. Also, respiratory and 
emergency care practitioners should be aware that 
bag-type oxygen reservoirs significantly impair the 
FDO2 capability of resuscitators used in cold weather 
conditions. 

ACKNOWLEDGMENTS 

We thank Ambu Inc. Hudson RCI, Laerdal Medical Corp, 
Matrx Medical Inc, Mercury Medical Inc, Puritan-Bennett Corp, 
Respironics Inc, and Vital Signs Inc for donating samples of 
their products for use in this study and for providing financial 
support to operate the environmental chambers. We thank the 
Commander and staff of the U.S. Army Research and 
Development Laboratories, Natick, Massachusetts, for 
permission to use their Climatic Chamber Facilities. We thank 
the following Northeastern University respiratory therapy 
students for their help in collecting data in the Arctic and Tropic 
Chambers: Gavin Adams, Mellisa Collins, Peter Dias, Michael 
Falkson, David Flood, and Diane Rita. We thank Jerry Schrader 
for his professional skill in photographing the resuscitators. 

PRODUCT SOURCES 

Manual resuscitators: 

(Note: Disposable units are sold 6 per case; prices are suppliers' 
list prices per unit as of November 28, 1990.) 

BagEasy, Respironics Inc, Murraysville PA, $20.50 

Code Blue, Vital Signs Inc, Totowa NJ, $19.85 

CPR Bag, Mercury Medical Inc, St Petersburg FL, $22.75 

DMR, Puritan-Bennett Corp, Overland Park KS, $19.95 

Hope 4, Matrx Medical Inc, Orchard Park NY, $1 19.00 

Laerdal, Laerdal Medical Corp, Armonk NY, $157.25 

Lifesaver, Hudson RCI, Temecula CA, $177.90 

Mark 3, Ambu Inc, Hanover MD, $192.50 

PMR, Puritan-Bennett Corp, Overland Park KS, $125.25 

SPUR, Ambu Inc, Hanover MD, $20.95 

Test lung: 

Model VT-1 Ventilator Tester, Bio-Tek Instruments Inc, 

Winooski VT 
Vent-Aid Training Test Lung (TTL), Michigan Instruments, 

Grand Rapids MI 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



171 



MANUAL RESUSCITATOR PERFORMANCE FROM -18°C to 50°C 



Calibration analyzer: 

Model RT-200 Calibration Analyzer System, Timeter 
Instrument Corp, Lancaster PA 

Oxygen monitor: 

Beckman OM-15 Oxygen Monitor, SensorMedics Corp, 
Anaheim CA 

Ametek S-3A/1 Oxygen Analyzer, Ametek Inc, Pittsburgh 
PA 

Respirometer: 

Model L-D Panel-Mounted Wright Respirometer, formerly 
marketed by Fraser Harlake Inc, Orchard Park NY; now 
marketed by Ferraris, Medical Inc, Holland NY 

Flowmeter: 

Pressure-Compensated Thorpe-Tube Flowmeter, 
Puritan-Bennett Corp, Overland Park KS 

Statistical software: 

Exstatix, version I.O.I, (1988), Select Micro Systems Inc, 
Yorktown Heights NY 

Data Monitor: 

Macintosh IIX computer and Two Page Monitor, Apple Corp, 
Cupertino CA 

REFERENCES 

1. Bossaert L, Van Hoeyweghen R. Evaluation of cardio- 
pulmonary resuscitation (CPR) techniques. The cerebral 
resuscitation study group. Resuscitation I989;(I7 
Suppl):SI99-S206. 

2. Cummings RO, Austin D, Graves JR, Litwin PE, Pierce 
J. Ventilation skills of emergency medical technicians: 
A teaching challenge for emergency medicine. Ann Emerg 
Med 1986;15:1187-1192. 

3. American Society for Testing and Materials. Standard 
specification for performance and safety requirements for 
resuscitators intended for use with humans. Designation: 
F-920-85. Philadelphia: Am Soc Testing & Materials, 
1985. 



4. International Organization for Standardization. Interna- 
tional Standard ISO 8382: 1988 (E) Resuscitators intended 
for use with humans. New York: American National 
Standards Institute, 1988. 

5. Emergency Care Research Institute. Pulmonary resusci- 
tators. Health Devices 1989;18:333-352. 

6. Hess D, Goff G, Johnson K. The effect of hand size, 
resuscitator brand, and use of two hands on volumes 
delivered during adult bag-valve ventilation. Respir Care 
1989;34:805-810. 

7. Hess D, Goff G. The effects of two-hand versus one- 
hand ventilation on volumes delivered during bag-valve 
ventilation at various resistances and compliances. Respir 
Care 1987;32:1025-1028. 

8. Barnes TA, McGarry WP. Evaluation of ten disposable 
manual resuscitators. Respir Care 1990;35:960-968. 

9. Barnes TA, Potash R. Evaluation of five adult disposable 
operator-powered resuscitators. Respir Care 1989;34:254- 
261. 

10. Eaton JM. Adult manual resuscitators. Br J Hosp Med 
1984;31:67-70. 

11. Barnes TA, Watson ME. Oxygen delivery performance 
of old and new design of the Laerdal, Vitalograph, and 
Ambu adult manual resuscitators. Respir Care 
1983;28:1121-1128. 

12. Priano L, Ham J. A simple method to increase the FDO2 
of resuscitator bags. Crit Care Med 1978;6:48-49. 

13. National Climatic Data Center. 1988 U.S. Local Climatic 
Annual Summary. Asheville NC: Data Operations Branch, 
National Climatic Data Center, 1988. 

14. Klick J, Bushnell L, Bancroft M. Barotrauma: A potential 
hazard of manual resuscitators. Anesthesiology 
1978;49:363-365. 

15. Standards and guidelines for cardiopulmonary resusci- 
tation and emergency cardiac care. JAMA 1 986;255 :284 1 - 
3044. 

16. EUingsen I, Sydnes G, Hauge J, Zwart A, Liestol K, 
Nicolaysen G. CO2 sensitivity in human breathing 1 or 
2% CO, in air. Acta Physiol Scand 1986;129:195-202. 



172 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



Total Opacification of the Left Hemithorax after 

Relief of Endobronchial Obstruction 

by Foreign Body — ^A Case Report 

Leland Hanowell MD, David Thurston MD, Sulpicio Soriano MD, and Walter R Martin MD 

We report the case of a 2-year-old boy who aspirated a fragment of a walnut 
and shell. Two days after the incident, the child was in respiratory distress and 
was referred to our medical center. Rigid bronchoscopy was performed, and the 
foreign body was removed from the left main-stem bronchus; however, the left 
chest failed to expand fully with positive-pressure ventilation. An intraoperative 
radiograph revealed complete opacification of the left lung, suggestive of unilateral 
pulmonary edema; however, leftward mediastinal shift was suggestive of massive 
atelectasis and lung collapse. Repeat bronchoscopy failed to reveal additional foreign 
bodies; however, airway edema was observed, and a copious amount of clear 
serosanguinous fluid was suctioned from the left main-stem bronchus. Reexpansion 
of the left lung occurred following administration of nebulized racemic epinephrine. 
An understanding of the physiologic changes associated with endobronchial 
obstruction and relief of such obstruction is prerequisite to providing appropriate 
therapy based on radiologic and clinical monitoring during perioperative 
management of endobronchial foreign-body obstruction. (Respir Care 1991;36: 
173-177.) 



Introduction 

Airway obstruction can be a life-threatening 
disorder in the pediatric patient. We describe a 
complication, detected by intraoperative radio- 
graphs, that followed removal of an endobronchial 
foreign body. The case illustrates appropriate 
anesthetic, surgical, and intensive-care management 
of airway obstruction, based on radiologic and 
clinical monitoring. 



Case Summary 



Dr Hanowell is Assistant Professor and Dr Thurston is Senior 
Resident, Department of Anesthesiology, University of 
California, Davis Medical Center — Sacramento, California. Dr 
Soriano is a Fellow, Department of Anesthesiology, Children's 
Hospital — Boston, Massachusetts. Dr Martin is a Fellow, 
Divisions of Pulmonary Medicine and Infectious Disease, 
University of California, Davis Medical Center — Sacramento, 
California. 

Reprints: Leland Hanowell MD, Dept of Anesthesiology, Univ 
of California, Davis Medical Center, 2315 Stockton Blvd, 
Sacramento CA 95817. 



History 



A 2-year-old Caucasian boy was referred from 
a community hospital for management of respiratory 
distress associated with suspected aspiration of a 
foreign-body into the airway. According to the 
mother, the child had exhibited paroxysmal cough 
after ingesting walnuts 2 days prior to admission. 
A chest radiograph at the referring hospital had 
demonstrated air trapping in the left hemithorax. 
The child, who had a history of good health prior 
to this episode, was brought to the university medical 
center for further evaluation. 

Physical Examination 

The well-developed, anxious 14-kg child was in 
moderate respiratory distress — respiratory rate 40/ 
min, heart rate 150/min, blood pressure 100/45, and 
temperature 38.6°C. There was no cyanosis. The 
child's eyes, ears, nose, and throat appeared normal. 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



173 



OPACIFICATION FOLLOWING RELIEF OF OBSTRUCTION 



Abbreviations Used in this Paper 

IMV — Intermittent mandatory ventilation 

P((A-a)02) — Alveolar-arterial oxygen-tension 

gradient 
PCV — Pressure-controlled ventilation 

PIP — Peak inspiratory pressure 

PEEP — Positive end-expiratory pressure 

A Guide to the Use of SI in this Paper* 

The SI unit for pressure is the kilopascal (kPa). 
(cm H2O)(0.098 06) = kPa. 



*For further information on SI (le Systeme International 
d'Unites), see Respir Care 1988;33:861-873 (October 
1988) and Respir Care I989;34:145 (February 1989— 
Correction). 



but coarse breath sounds were audible without a 
stethoscope. Decreased excursion of the left chest 
was noted. Auscultation revealed diminished breath 
sounds in the left chest and coarse wheezes in the 
right chest. Suprasternal and intercostal retractions 
were noted. Cardiac and other physical examinations 
were normal. No intravenous access was present. 
Figure 1 shows the radiographic appearance of the 
chest immediately prior to surgical intervention. 




Fig. 1 . Chest radiograph of a 2-year-old boy in respiratory 
distress associated with suspected foreign-body aspira- 
tion, taken immediately prior to bronchoscopic 
intervention. 



Intraoperative Course 

The child was taken to the operating room where 
100% oxygen was administered via a standard face 
mask and anesthetic circle system. Halothane was 
delivered during spontaneous ventilation until loss 
of consciousness, at which time a peripheral venous 
catheter was inserted. While a rigid bronchoscope 
was prepared for insertion, atropine 0.2 mg and 
atracurium 5.0 mg were administered intravenously, 
and isoflurane was substituted for halothane to 
maintain general anesthesia. After the onset of 
neuromuscular relaxation, documented by loss of 
twitch response to peripheral nerve stimulation, the 
rigid bronchoscope was inserted and a large, hard 
fragment of a walnut and shell was removed from 
the left main-stem bronchus. Controlled ventilation 
was initiated, and bronchoscopic inspection of the 
airway was carried out. Edema and inflammation 
of the mucosa surrounding the carina and gener- 
alized tracheal irritation were observed. 

After bronchoscopic removal of the foreign body, 
the left chest failed to expand fully with positive- 
pressure ventilation. Breath sounds in the left chest 
continued to be diminished despite use of peak 
inflation pressures of 35 cm H2O [3.4 kPa]. An 
intraoperative radiograph was taken that revealed 
complete opacification of the left lung (Fig. 2). 
Bronchoscopy was repeated. No additional foreign 
bodies were disclosed, but a copious amount of clear, 
serosanguinous fluid was suctioned from the left 
main-stem bronchus and sent for bacteriologic 
culture. A nasogastric tube was inserted and attached 
to suction, and the bronchoscope was replaced with 
a cuffless endotracheal tube. Arterial oxygen 
saturation was 90% despite delivery of 100% 
oxygen. Nebulized racemic epinephrine was 
delivered via the inspiratory limb of the anesthetic 
circuit, yielding improved ventilation of the left lung 
and increased excursion of the left chest wall. 



Postoperative Course 

A radiograph taken in the recovery room showed 
partial resolution of the left-lung opacification. 
Arterial blood analysis, performed while the child 
was mechanically ventilated with 100% oxygen in 
the intermittent mandatory ventilation (IMV) mode, 



174 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



OPACIFICATION FOLLOWING RELIEF OF OBSTRUCTION 




Fig. 2. Chest radiograph of a 2-year-old boy in respiratory 
distress, taken immediately following bronchoscopic 
removal of a large, hard fragment of a walnut and shell 
from the left-main-stem bronchus. 



revealed Pa02 203 torr [27.1 kPa], Pacoj 37 torr 
[4.9 kPa], and pH 7.29. 

Pressure-controlled ventilation (PCV), with peak 
inspiratory pressure (PIP) of 20 cm H2O [2.0 kPa] 
and positive end-expiratory pressure (PEEP) of 5 
cm H2O [0.5 kPa], was instituted but was 
successfully discontinued on the first postoperative 
day. Arterial blood analysis revealed prompt 
resolution of metabolic acidosis. Reduction in the 
alveolar-arterial oxygen-tension gradient 
[P(A-a)0')]> during the 24-hour period following 
bronchoscopy, suggested resolution of pulmonary 
shunt. Stridor, following extubation, was managed 
with aerosolized racemic epinephrine and intrav- 
enous dexamethasone. Antibiotics were adminis- 
tered, but no specific pathogens were cultured. 
Fever, respiratory distress, and radiographic 
abnormalities resolved, and the child was discharged 
in stable condition on the fourth hospital day. 



Discussion 

This case illustrates routine management of 
pediatric foreign-body aspiration. However, the 
possible cause of the left-lung opacification seen 
on the intraoperative radiograph was a source of 
much speculation. The left-lung opacification was 
striking, suggestive of possible unilateral pulmonary 
edema; however, the leftward mediastinal shift 
(evident by the absence of the right heart border) 
was more suggestive of massive atelectasis and left- 
lung collapse. 

The high concentration of oxygen administered 
during bronchoscopy and the vigorous suctioning 
of copious secretions could have contributed to lung 
collapse. Absorption atelectasis can occur in poorly 
ventilated alveoli distal to airway obstruction, but 
gross atelectasis was not apparent in this child's 
preoperative chest radiograph. Persistently de- 
creased breath sounds and decreased excursion of 
the left chest wall suggested a retained foreign body. 

Repeat bronchoscopy revealed only airway 
edema. The improvement in ventilation of the left 
lung after the administration of aerosolized racemic 
epinephrine suggests that this airway edema may 
have contributed to the left-chest abnormalities, 
although the bronchodilatory effects of nebulized 
racemic epinephrine also may have been therapeutic. 
Copious fluid aspirated from the left lung after the 
radiographic detection of unilateral lung opacifica- 
tion, though suggestive of unilateral pulmonary 
edema, does not confirm that this entity was present. 

The prompt clearing of radiographic abnormal- 
ities observed in this case is compatible with either 
atelectasis or pulmonary edema. 

Atelectasis or Pulmonary Edema? 

Pulmonary edema. Pulmonary edema secondary 
to airway obstruction has been frequently described. 
Price and Hecker' described bilateral pulmonary 
edema subsequent to airway obstruction due to 
mediastinal tumor. Shumaker et aP described 
bilateral pulmonary edema subsequent to strangu- 
lation injury in an 11 -year-old boy. Lavertu and 
Gervais^ reported recurrent episodes of pulmonary 
edema, each following partial airway obstruction 
due to incomplete resection of epiglottic tumor. 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



175 



OPACIFICATION FOLLOWING RELIEF OF OBSTRUCTION 



Surgical excision of residual epiglottic tissue 
resolved these episodes. Szucs and Floyd'' described 
pulmonary edema following relief of laryngospasm 
occurring after tracheal extubation. Warner et aP 
noted pulmonary edema in an infant after a brief 
period of endotracheal -tube obstruction. Scherer et 
al* reported a case of pulmonary edema that followed 
relief of partial upper-airway obstruction (subglottic 
swelling) subsequent to endotracheal intubation for 
general anesthesia. Galvis^ reported 20 cases of 
bilateral pulmonary edema after relief of upper- 
airway obstruction in children. 

Unilateral pulmonary edema associated with 
unilateral airway obstruction has been previously 
reported. Shikhani et al** reported a case of unilateral 
pulmonary edema associated with contralateral 
bronchial obstruction. The mechanism was unclear; 
however, the unilateral pulmonary edema they 
described was thought to have occurred prior to 
alleviation of contralateral airway obstruction. 
Kramer et al^ described unilateral pulmonary edema 
associated with right-main-stem intubation. Pulmo- 
nary edema in their three elderly patients followed 
resuscitation from cardiac arrest, but preceded relief 
of left endobronchial obstruction by endotracheal- 
tube repositioning. 

Inspiratory effort against an obstructed airway 
generates negative interstitial pressure and promotes 
edema formation. This phenomenon is explained 
by the Starling equation: 1° 

Q = K(Pc-P,)-(TC,-7C,), 

where Q is the rate of fluid flow across the capillary 
membrane; K is the filtration coefficient; Pc is the 
capillary hydrostatic pressure, Pt is the interstitial 
hydrostatic pressure, n^. is capillary oncotic pressure, 
and Uf is interstitial oncotic pressure. If Pt becomes 
a negative value, movement of fluid out of the 
capillaries and into the interstitium is facilitated. 
Stalcup and Mellins'i measured mean pleural 
pressures up to -25.5 cm HjO [-2.50 kPa] and peak 
inspiratory pressures up to -38.8 cm H2O [-3.80 
kPa] in pediatric asthmatics. 

Capillary hydrostatic pressure can rise acutely 
during hypoxia due to a shift of systemic blood 
to the lung. Hypoxic pulmonary vasoconstriction 
in some segments of the lung can also shift blood 
flow to a reduced portion of the pulmonary 



vasculature. Subsequent to lung reexpansion, if 
capillary membrane integrity is impaired, pulmo- 
nary edema may ensue. 

Atelectasis. Radiographic infiltrates and atelectasis 
occur in at least 30% of pediatric foreign-body 
aspirations, although nearly half of the children 
presenting with this disorder will have normal chest 
radiographs. '2 Our patient had no atelectasis on his 
admission radiograph (Fig. 1); however, the 
intraoperative chest film (Fig. 2) clearly shows 
volume loss in the left lung with leftward mediastinal 
shift, indicative of atelectasis or left-lung collapse. 
Close inspection by a radiologist may discern subtle 
radiographic abnormalities in the majority of 
children with foreign-body aspiration. Unilateral 
emphysema, a common finding after foreign-body 
aspiration, can be more readily discerned in 
expiratory films. 

Atelectasis occurring during general anesthesia 
may present in a variety of clinical settings. 
Generally it is associated with mucus plugging and 
occasionally may be profound and result in 
hypoxemia.'-^ Inadvertent intubation of the right 
main-stem bronchus may result in left-lung 
atelectasis and/or right-upper-lobe atelectasis if the 
endotracheal tube occludes the right-upper-lobe 
bronchus. 

Atelectasis may be a factor in the development 
of reexpansion pulmonary edema. Intrapleural 
pressure may decrease when atelectasis develops. 
Atelectasis developing under circumstances of 
reduced intrapleural pressures is associated with 
impaired hypoxic pulmonary vasoconstriction.''' 
Relative hyperperfusion of atelectatic lung may lead 
to circumstances favoring edema formation. 

Summary 

Atelectasis after aspiration and subsequent 
removal of a foreign body was associated with left- 
lung opacification. Reexpansion or postobstruction 
pulmonary edema is a possible sequela associated 
with the relief of airway obstruction, though not 
confirmed in our patient. Retained foreign body, 
bronchospasm, airway edema, atelectasis, and 
pulmonary edema must be considered in the 
differential diagnosis of unilateral lung opacification 



176 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



OPACIFICATION FOLLOWING RELIEF OF OBSTRUCTION 



after relief of airway obstruction. Effective 
management of airway obstruction requires 
radiographic and clinical monitoring for pulmonary 
sequelae associated with the relief of airway 
obstruction. 

REFERENCES 

1. Price SL, Hecker BR. Pulmonary oedema following 
airway obstruction in a patient with Hodgkin's disease. 
BrJAnaesth 1987;59:518-521. 

2. Shumaker D, Kottamasu S, Preston G, Treloar D. Acute 
pulmonary edema after near strangulation. Pediatr Radiol 
1988;19:59-60. 

3. Lavertu P, Gervais AJ. Recurrent noncardiogenic 
pulmonary edema secondary to obstruction by hemiepi- 
glottic remnant. J Otolaryngol 1988;17:229-232. 

4. Szucs RA, Floyd HL. Laryngospasm-induced pulmonary 
edema. Radiology 1989; 170:446. 

5. Warner LO, Beach TP, Martino JD. Negative pressure 
pulmonary oedema secondary to airway obstruction in 
an intubated infant. Can J Anaesth 1988;35:507-510. 



6. Scherer R, Dreyer P, Jorch G. Pulmonary edema due 
to partial upper airway obstruction in a child. Intensive 
Care Med 1988;14:661-662. 

7. Galvis AG. Pulmonary edema complicating relief of upper 
airway obstruction. Am J Emerg Med 1987;5:294-297. 

8. Shikhani AH, Salman SD, Melhem R. Unilateral 
pulmonary edema as a complication of contralateral 
bronchial obstruction. Laryngoscope 1987;97:748-751. 

9. Kramer MR, Melzer E, Sprung CL. Unilateral pulmonary 
edema after intubation of the right mainstem bronchus. 
Crit Care Med 1989;17:472-474. 

10. Starling EH. On the absorption of fluids from the 
connective tissue spaces. J Physiol 1896;9:312-326. 

11. Stalcup SA, Mellins RB. Mechanical forces producing 
pulmonary edema in acute asthma. N Engl J Med 
1977;297:592-596. 

1 2. Laks Y, Barzilay Z. Foreign body aspirations in childhood. 
Pediatr Emerg Care 1988;4:102-106. 

13. Samuels SI, Brodsky JB. Profound intraoperative 
atelectasis. Br J Anaesth 1989;62:216-218. 

14. Chen L, Williams JJ. Alexander CM, Ray RJ, Marshall 
C, Marshall BE. The effect of pleural pressure on the 
hypoxic pulmonary vasoconstrictor response in closed 
chest dogs. Anesth Analg 1988;67:763-769. 



CORRECTION 

A production error occurred in AJ Beechko's response (Bear Medical) to the Monaco 
and Goettel letter entitled "Increased Airway Pressures in BEAR 2 and 3 Circuits 
following Airway-Pressure-Line Disconnection," which appeared in the February issue 
(Respir Care 1991;36:132-133). The fourth full paragraph should have begun as shown 
below. We regret the error. 

The Low Pressure Alarm is the first activated in the situation described by Monaco 
and Goettel. This alarm is activated when a positive pressure breath is delivered that 
is unable to transcend machine pressure above and below the threshold established 
by the alarm setting. Next, within 7-9 seconds of the commencement of compensatory 
flow of > 22 L/min, the Loss of PEEP Alarm will activate due to the intemal-flow- 
transducer monitoring system. 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



177 



Special Articles 



Oxygen-Conservers, Home Oxygen Prescriptions, and 
the Role of the Respiratory Care Practitioner 



John W Shigeoka MD 



Oxygen-conserving devices have been available 
for several years, offering a solution to the problems 
of conventional continuous-flow oxygen therapy — 
namely, wasteful flow, inconvenience, and expense. 
A 1985 editorial in this journal discussed the status 
of oxygen-conservers (the transtracheal catheter, 
reservoir cannula, and demand valve) and indicated 
that they offered the potential to substantially reduce 
oxygen costs and improve the quality of life for 
patients with chronic hypoxemia.' However, 
physicians, vendors, payers, and patients were not 
anxious to support this new technology. Since that 
editorial was published, profound changes in home 
oxygen reimbursement have altered prescribing 
practices and attitudes toward oxygen-conservers. 
Further, these changes may affect the role of 
respiratory care practitioners in home oxygen 
therapy. This paper reviews these changes. 

The Medicare Home Oxygen 
Reimbursement Problem 

In 1985, the Health Care Financing Administra- 
tion (HCFA-Medicare) announced a new policy of 
standardized prescription and reimbursement for 
home oxygen therapy to eliminate unreasonable and 



Dr Shigeoka is Chief, Pulmonary Section, Department of 
Veterans Affairs Medical Center; and Medical Director, 
Respiratory Care Center, University of Utah Medical Center — 
Salt Lake City, Utah. 

This paper is neither an endorsement nor a criticism of any 
specific commercial product by the author, the Department 
of Veterans Affairs, or this journal. 

Reprints: John W Shigeoka MD, Pulmonary Section, 11 IB, 
VA Medical Center, 500 Foothill Blvd, Salt Lake City UT 
84148. 



unnecessary prescription, simplify administration, 
and reduce program costs.^ Health care profes- 
sionals,-''4 the National Association of Medical 
Equipment Suppliers, and others worked closely 
with HCFA to modify the new policy that became 
law in 1987 and was implemented in 1989. Because 
Medicare is the largest single payer,^ this new policy 
has had major effects on home oxygen services. 
Unfortunately, much of the effect has been negative. 

Problems with Form 484 

The very complicated Certificate of Medical 
Necessity (CMN) for Home Oxygen Therapy 
(HCFA Form 484) serves as a prescription and 
justification.^ It was not well understood that a 
physician should complete the CMN before a patient 
is discharged from the hospital on oxygen therapy. 
Failure to complete the form before discharge 
created havoc for physicians and vendors unfamiliar 
with the new policy. Physicians belatedly discovered 
that they needed the patient's medical record to 
provide the necessary information, such as blood 
gas results. Because records are notoriously difficult 
to obtain immediately after discharge, certification 
was delayed. To worsen matters, Medicare 
administrators denied payment if physicians failed 
to use approved terminology, to conform to strict 
criteria, and to provide specific justifications. To 
expedite certification and payment, some vendors 
entered the necessary laboratory results, approved 
terminology, and justifications on the form that the 
physicians later reviewed and signed. Unfortunately, 
HCFA considered this practice to be too vulnerable 
to inappropriate prescription and has mandated that 
only physicians or their designated employees 
complete the CMN. Alarmed vendors and patients 
began to pester physicians for the delinquent or 



178 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



HOME OXYGEN THERAPY & MEDICARE 



revised CMN, and paperwork rapidly became 
onerous. 

Problems with the New Rates 

The new simplified monthly payment for oxygen 
is based on the average of local costs for liquid, 
cylinder, and concentrator oxygen. It applies to 
stationary equipment at flows of 1 to 4 L/min and 
is modified only for extremes of flow (50% of base 
if < 1 L/min and 150% if > 4 L/min), for annual 
inflation, and for a scheduled conversion to regional 
costs. There is a small supplement for portable 
equipment. In 1990, our Medicare administrator paid 
$232 plus a $40 supplement for portable equipment; 
the total reimbursement was one third lower than 
in 1987!^ The new rates have discouraged the use 
of portable equipment and the more convenient 
liquid-oxygen system. 

Additional Factors 

Recently the Joint Commission on Accreditation 
of Healthcare Organizations has required that 
vendors document infection control, maintenance, 
repair, safety, patient instruction, and proper 
operation of durable medical equipment in the 
home.^ This documentation and the sudden jump 
in gasoline prices have increased vendors' operating 
costs. 

The Effect of the New Policies 

Poor prescribing practices, complex paperwork, 
and the new Medicare payment rates have reduced 
cash flow for vendors who also now have higher 
operating expenses. One ironic result is that some 
vendors now advocate less expensive (but less 
convenient) equipment that gives them a higher 
profit margin. Thus, some patients are using less 
convenient equipment and others are tethered to their 
stationary equipment. 

It is clear that oxygen-conservers should receive 
more attention. If patients had them, vendors could 
make fewer deliveries and reduce their operating 
expenses, and patients could ambulate longer with 
lighter, more convenient equipment. The need is 
not restricted to Medicare patients; vendors have 
recently restructured prices, and our Medical Center 



costs have risen dramatically. Therefore, let us look 
at what oxygen-conserver technology offers today. 

Oxygen-Conserver Technology 

Transtracheal Oxygen Catheter 

This device reduces dead space, provides a larger 
anatomic reservoir, reduces expiratory loss of 
oxygen, eliminates nasal irritation, and is less 
conspicuous than a nasal cannula. 'The original 
simple catheter^ has been withdrawn from the 
market because of problems with kinking. A more 
complex system (SCOOP, Transtracheal Systems, 
Denver CO) provided an average 55% reduction 
of oxygen flow in the first 100 patients and had 
few complications such as mucus plugging, 
subcutaneous emphysema, cellulitis, malplacement, 
and hemoptysis.'" Others reported a higher 
frequency of complications that may reflect, in part, 
the problems associated with establishing a new 
program." SCOOP patients must be motivated to 
undergo a 7-week program and be able to care for 
the mini-tracheostomy site and catheter. 'o Our 
Medicare insurer supports part of the cost of the 
minor surgical procedure and of the expensive 
($100) catheters that are replaced every 90 days. 
A special low-flow flowmeter (eg, 0-4 L/min full 
scale) may be required for greatest oxygen savings. 

Reservoir Nasal Cannula and 
Pendant Reservoir Cannula 

These store oxygen during expiration and deliver 
a 20-mL bolus during early inspiration (Oxymizer 
and Oxymizer Pendant, Chad Therapeutics, 
Chatsworth CA). A 1985 paper reported that the 
reservoir nasal cannula reduced oxygen flow 75% 
at rest and 50% during exercise. '^ However, patients 
do not readily accept the device's mustache 
appearance. The more attractive pendant device was 
shown in 1986 to reduce oxygen flow 67% during 
exercise. '3 In contrast, a study in the home setting, 
published in 1987, found an average 35% oxygen 
savings and $71 in cost savings during a month- 
long evaluation. '■♦ In this study, discomfort 
substantially reduced patient compliance in using 
the pendant, and replacement costs of $6/week offset 
cost savings. When patients tolerated the pendant, 
oxygen savings averaged 53% and cost savings 
$141. This study illustrates the importance of long- 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



179 



HOMF OXYGEN THFRAPY & MEDICARE 



Table 1 . A Comparison (for Discussion Only, Not for Patient Care) of Three Oxygen Demand Values 



Attribute 



Valve X 



Valve Y 



Valve Z 



Size (cm) 

Weight (g) 

Regulator required 

Settings (L/min) 

Ease of setting 

Ease of setting 
for exercise 



9x6x 12 


9 X 6 X 20 


10.5 X 14 X 5 


370 


890 


890 


special pressure 


conventional flow 


special flow 


1-5 


1,1.5,2,2.5,3,3.5,4,5 


0.5,1,1.5,2,3,4,5 


excellent 


poor to fair 


good 


excellent 


fair (both regulator & valve 


good (regulator had to be 




had to be adjusted to higher 


adjusted to higher flows during 




flow for exercise, then 


exercise, then changed back) 



changed back) 



Sensitivity 



poor to fair (failed to detect 
inspiration in sleeping 
patients — manufacturer now 
recommends model not be 
used during sleep) 



excellent 



excellent 



Laboratory savings 



83% at lObpm* 
66% at 20 bpm 
32% at 40 bpm 



50-60% at 8-50 bpm 
(computer switches to continu- 
ous flow if respiratory rate is 
out of 8 to 50-bpm range or is 
chaotic) 



60% at 10 bpm, 
55% at 15 bpm 
(valve failed to actuate in 
phase when respiratory 
rate > 20 bpm and failed to 
maintain O2 saturation) 



Battery operation 

Solenoid position, 
if power fails 



6-8 h 

closed (no oxygen flows; over- 
ride switch must be changed 
manually to continuous 
position) 



3-4 h 



open 



3-4 h 



open 



Alarm loudness 



poor to fair 



poor to fair 



poor to fair 



*bpm = breaths/min. 



terrn field investigations (in contrast to brief 
laboratory studies), the need for others to verify 
the initial reports of a device's inventor or 
manufacturer, '5 and the difference between oxygen 
savings and cost savings. Unfortunately, our 
Medicare carrier does not support the cost of the 
reservoir cannula or pendant. 



Demand Oxygen Valve 

This device reduces expiratory waste of oxygen 
by restricting deliver)' to inspiration, and it may 
minimize dead-space loss by delivering oxygen in 
early inspiration.' Their noninvasive and relatively 
inconspicuous nature may explain why demand 



180 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



HOMF OXYGEN THF.RAPY & MEDICARE 



oxygen valves are popular — a recent home health 
care trade journal listed 11 manufacturers!'^ 

Unfortunately, experience remains limited. 
Published evaluations have involved small numbers 
of subjects studied for brief periods under controlled 
conditions, with oxygen savings reported from 55% 
to 88%. '''■23 Different operating characteristics of 
the various models make it difficult to pool 
information. This can be seen by examining three 
demand oxygen valves that have the following 
similarities: cost of $500, built-in rechargeable 
batteries, and alarms (Table 1). Valve X has 
advantages for ambulatory patients who are 
observant and able to switch to continuous mode 
when the batteries are discharged. Because this 
model can be used only during waking hours, overall 
oxygen savings will be less than those seen in 
laboratory studies. Valve Y has advantages for those 
less active patients who need a computerized device 
that switches to continuous flow when breathing 



rate changes drastically or the batteries are 
discharged. Valve Z does not seem to offer any 
advantage. Thus, although the three valves 
superficially resemble each other, they are quite 
different. 

The lack of long-term field studies of demand 
valves' performance and reliability remains a major 
problem. The threat of rapid technologic obsoles- 
cence may explain why investigators are reluctant 
to perform such investigations and why vendors 
have been cautious about purchasing demand valves. 

Because of pressing needs, it would be wise for 
manufacturers to pool resources, to consider trading 
(cross-licensing) proprietary technology, and to plan 
continued refinements with medical advice. Some 
problems with current valves might be solved by 
simply adopting technology from the electronics 
industry (Table 2). Other problems might be solved 
by cross-licensing; for example, the pulsed-dose 
concept might be traded for the computer- 



Table 2. Problems with Current Demand Valves and Possible Solutions* 



Problem 



Comments 



Solution 



Precedent 



Internal batteries hold limited short ambulatory time and long snap-on power packs 
charge recharge time 



camcorder power packs 



Heavy, bulky regulators 



traditional design in brass; sta- 
tionary and portable units use 
different fittings 



compact design in aluminum; 
quick-connect coupler 



compact cameras in alloys and 
plastic; electronic flash 
couplers for different cameras 



Excess weight and size 



ambulatory and stationary 
needs differ 



modular design; simple valve 
for ambulation with bedside 
unit for more sophisticated 
options (see below) 



laptop computer with desktop 
docking station for options 
(color CRT, modem, printer) 



Sensitivity is too low for sleep different inspiratory signal 
yet too high for activity strengths require different 

sensitivity settings 



bi-level sensitivity switch; low FM radio with distant and 
for exercise and high for sleep local station settings 



Alarms are too quiet or dim 



the elderly may not hear or 
see well 



extra loud and bright alarms in clock radio alarm; radio 
bedside unit; telemetry for intercom 

nearby family member 



*A partial listing of problems with current demand valves (see Table 1) and potential solutions that may be adapted from precedents 
found in the electronics industry. 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



181 



HOME OXYGEN THERAPY & MEDICARE 



monitored-valve concept. Some problems may 
require additional research — for example, the safe 
use of demand valves during sleep^^ (Table 2). 
Furthermore, marketing decisions may not be 
medically sound; for example, a manufacturer may 
consider an apnea alarm too costly, yet clinicians 
recognize how commonly nasal cannulas become 
dislodged during sleep. 

The technical aspects of oxygen-conservers have 
been reviewed by O'Donohue^^ and by Tiep and 
Lewis.26 

Now and in the Future 

The new Medicare policy has changed how long- 
term oxygen therapy is prescribed and provided. 
Evaluating the need for chronic home oxygen 
therapy must be part of hospital-discharge planning. 
Physicians are more objective and altruistic than 
profit-minded vendors and economy-minded payers 
when making important therapeutic decisions for 
their patients. Thus, physicians, not vendors, must 
select the most appropriate therapy based on patient 
need and availability of equipment,''^'' must enter 
the information supporting that decision on Form 
484, and must provide the vendor with enough time 
before discharge to properly train the patient and 
family to use the equipment.^ With this approach, 
patients will benefit from carefully selected therapy 
and training, payers will no longer have to support 
unnecessary or inappropriate therapy, physicians 
and medical records departments will be spared post- 
discharge requests, and vendors will have better cash 
flow. 

Respiratory care practitioners should play a larger 
role in the assessment for chronic home oxygen 
therapy. Wise physicians will leam that informed 
respiratory care practitioners can help them select 
the most appropriate equipment systems and titrate 
oxygen doses. The latest version (5/90) of the CMN 
allows designated employees of the physician to 
enter the necessary information that the physician 
must later review and sign. 

Finally, there is a need to support the cost of 
oxygen-conservers more consistently. The Medicare 
half-rate provision for flows < 1 L/min discourages 
the use of transtracheal catheters and reservoir 
conservers that operate by reducing oxygen flow. 
It is unclear why our Medicare insurer supports 
replacement transtracheal catheters but not reservoir 



cannulas that have the same annual cost. In turn, 
the cost of replacing transtracheal catheters for two 
years would equal the cost of purchasing a demand 
valve. In this regard, there may be hope. The 
appearance on the CMN of a check box for oxygen- 
conserving devices suggests that HCFA might be 
willing to spend a little money to save money — 
possibly as a small supplement for disposable 
conservers or demand-valve rental fees. Clinicians, 
patients, and the home oxygen industry should be 
prepared when this happens! 

REFERENCES 

1 . Shigeoka JW, Bonekat HW. The current status of oxygen- 
conserving devices (editorial). Respir Care 1985;30:833- 
836. 

2. Department of Health and Human Services, Health Care 
Financing Administration. Medicare program: Coverage 
of oxygen for use in a patient's home. Fed Register 
1985;50: 13,742-750. 

3. Conference report. Problems in prescribing and supplying 
oxygen for Medicare patients. Am Rev Respir Dis 
1986;134:340-341. 

4. Conference report. Further recommendations for 
prescribing and supplying long-term oxygen therapy. Am 
Rev Respir Dis 1988;138:745-747. 

5. O'Donohue WJ Jr. The future of home oxygen therapy. 
Respir Care 1988;33:1125-1130. 

6. Conference report. New problems in supply, reimburse- 
ment, and certification of medical necessity for long-term 
oxygen therapy. Am Rev Respir Dis 1990;142:721-724. 

7. Shigeoka JW. The practical prescription of home oxygen 
therapy. In: Stults BM, Dere WD, eds. The practical care 
of the pulmonary patient. Philadelphia: WB Saunders Co, 
1989:467-476. 

8. Joint Commission on Accreditation of Healthcare 
Organizations. Standards for accreditation of home care. 
Chicago: JCAHO, 1988. 

9. Heimlich HJ, Carr GC. The micro-trach: A seven-year 
experience with transtracheal oxygen therapy. Chest 
1989;95:1008-1012. 

10. Christopher KL, Spofford BT, Petrun MD, McCarty DC, 
Goodman JR, Petty TL. A program for transtracheal 
oxygen delivery. Ann Intern Med 1987;107:802-808. 

1 1. Adamo JP, Mehta AC, Stelmach K, Meeker D, Rice T, 
Stoller JK. The Cleveland Clinic's initial experience with 
transtracheal oxygen therapy. Respir Care 1990;35:153- 
160. 

12. Soffer M, Tashkin DP, Shapiro BJ, Littner M, Harvey 
E, Farr S. Conservation of oxygen supply using a reservoir 
nasal cannula in hypoxemic patients at rest and exercise. 
Chest 1985;88:663-668. 

13. Carter R, Williams JS, Berry J, Peavler M, Griner D, 
Tiep B. Evaluation of the pendant oxygen-conserving 
nasal cannula during exercise. Chest 1986;89:806-810. 



1S2 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



HOME OXYGEN THERAPY & MEDICARE 



14. Claibom RA, Paynter DE, Dutt AK, Rowlands JW. 21. 
Evaluation of the use of an oxygen conservation device 

in long-term oxygen therapy. Am Rev Respir Dis 
1987;136:1095-1098. 22. 

15. Branson RD. The responsibility of medical-product 
evaluators and inventors to avoid conflict of interest 
(editorial). Respir Care 1988;33:769-770. 

16. Hamilton MNW. Modality choices: How to satisfy patient, 23. 
physician, and dealer needs; conserving device compar- 
ison chart. Home Care 1 989; 1 1(3, Special Suppl):20-2I. 

17. Tiep BL, Nicotra MB, Carter R, Phillips RR, Otsap B. 
Low-concentration oxygen therapy via a demand oxygen 24. 
delivery system. Chest 1985;87:636-638. 

18. McDonnell TJ, Wanger JS, Senn S, Chemiack RM. 
Efficacy of pulsed oxygen delivery during exercise. Respir 25. 
Care 1986;31:883-888. 

19. Rinow ME, Saltzman AR. Effectiveness of a new oxygen 26. 
demand valve in chronic hypoxemia. Chest 1986;90:204- 

207. 

20. Tiep BL, Carter R, Nicotra B, Berry J, Phillips R, Otsap 27. 
B. Demand oxygen delivery during exercise. Chest 
1987;91:15-20. 



Bower JS, Brook CJ, Zimmer K, Davis D. Performance 
of a demand oxygen saver system during rest, exercise, 
and sleep in hypoxemic patients. Chest 1988;94:77-80. 
Senn S, Wanger J, Fernandez E, Chemiack RM. Efficacy 
of a pulsed oxygen delivery system during exercise in 
patients with chronic respiratory disease. Chest 
1989;96:467-472. 

Kerby GR, O'Donohue WJ, Romberger DJ, Hanson FN, 
Koenig GA. Clinical efficacy and cost benefit of pulse 
flow oxygen in hospitalized patients. Chest 1990;97:369- 
372. 

Carter RC, Tashkin D, Djahed B, Hathaway EL, Nicotra 
MB, Tiep BL. Demand oxygen delivery for patients with 
restrictive lung disease. Chest 1989;96:1307-131 1. 
O'Donohue WJ Jr. Oxygen conserving devices. Respir 
Care 1987;32:37-42. 

Tiep BL, Lewis ML. Oxygen conservation and oxygen- 
conserving devices in chronic lung disease. Chest 
1987;92:263-272. 

Pierson DJ. The physician's role in the cost of long-term 
oxygen therapy. Respir Care 1987;32:339-344. 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



183 



Symposium Papers 



Long-Term Mechanical Ventilation Revisited 

David J Pierson MD and Roger S Goldstein MD 



Five years ago this Journal published a special 
issue devoted to long-term mechanical ventilation 
(LTMV). ' That issue's eight articles were developed 
from a 1985 postgraduate course presented jointly 
by the American Association for Respiratory Care 
(AARC) and the American College of Chest 
Physicians (ACCP). These articles remain a valuable 
resource for those involved in the care of patients 
managed with LTMV, whether this involvement is 
focused in the intensive care unit (ICU), the home, 
or the regulating agency. 

The foreword introducing the 1 986 special issue^ 
concluded with several comments and predictions 
about the future of LTMV in the home. It predicted 
that the number of patients receiving such therapy 
would increase. This has probably occurred during 
the intervening 5 years, although we have no more 
nationwide data than we did in 1985. It pointed 
out the need for hospital-based and community- 
based components of the health care delivery system 
to work together in preparing for and carrying out 
LTMV in the home, and this need has not changed. 
It predicted that more sophisticated devices and 
services would be used in the home, and indeed 
there has been a marked increase in this area. It 
emphasized the need for better funding and 
reimbursement for home LTMV, "as government 
agencies and private carriers acknowledge the 
financial advantages of care outside the hospital. "^ 
Although there is now greater awareness of the 
problem at several levels,^ the modest progress in 
reimbursement that has occurred has been at the 



Dr Pierson is Professor of Medicine, University of Washington, 
and Medical Director, Respiratory Care Department, Harbor- 
view Medical Center — Seattle, Washington. Dr Goldstein is 
Associate Professor of Medicine, University of Toronto, and 
Director, Respiratory Medicine, West Park Hospital — Toronto, 
Ontario, Canada. 



local level, and for specific individuals rather than 
across the board for all patients in need of LTMV. 

Finally, the 1986 editorial noted that as the 
numbers of ventilator-assisted patients increased, 
they would be increasingly visible as a special- 
interest group, and might well develop "a 'National 
Organization of Ventilator-Assisted Persons,' with 
its own advocates and publications, helping its 
members to participate more and more successfully 
in society. "2 In fact, an organization exactly fitting 
this description — the International Ventilator Users 
Network* — has been in existence for a number of 
years. That this excellent organization is not more 
widely known among health professionals and 
patients is an example of the need for better 
communication about all aspects of LTMV. 

The articles in the 1986 special issue focused 
on LTMV in patients for whom this therapy 
represents life support — that is, individuals unable 
to be weaned from the ventilator after acute 
respiratory failure. It was hoped that increased 
understanding of respiratory muscle function and 
the work of breathing might permit earlier and more 
accurate separation of weanable and unweanable 
patients. Furthermore, although good clinical 
evidence was lacking, the authors postulated that 
initiating ventilatory assistance electively in selected 
individuals might forestall acute respiratory failure 
and improve both gas exchange and daytime 
functional level in these patients. In the intervening 
5 years, there has been tremendous interest in this 
approach to LTMV, with numerous groups of 
investigators studying it and several companies 
introducing new ventilators and other apparatuses 
designed for this purpose. 

In this and the next issue of Respiratory Care, 
six articles revisit the subject of LTMV in the context 



*IVUN, 4502 Maryland Ave, St Louis MO 63108. 



184 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



of the 1990s. These articles were developed from 
a symposium presented at the 36th Annual 
Convention of the AARC in New Orleans on 
December 9, 1 990. The symposium was structured 
to emphasize the two distinct settings in which 
LTMV is now used: life support and elective 
therapy. 

This month the focus is on LTMV as life support, 
as in the 1986 papers. Stoller^ first reviews the 
factors determining the need for ventilatory support 
and offers guidelines for establishing clinical 
unweanability. In the second paper, Nochomovitz 
et aP describe the placement options currently 
available for ventilator-dependent patients who no 
longer need ICU care. To conclude this month's 
articles, Gilmartin^ draws on her vast clinical 
experience in managing ventilator-dependent 
patients outside the hospital, and offers specific 
practical guidelines for selecting appropriate 
patients and preparing them for management in the 
home. 

Next month the focus is on LTMV as elective 
therapy. Stoller'' first discusses the theoretical and 
physiologic reasons for attempting such therapy in 
the light of the natural history of chronic respiratory 
insufficiency in different clinical settings. 
Spearman** then provides an update on ventilators 
and other equipment available for home use. Finally, 
Goldstein and Avendano^ place elective LTMV in 
a clinical perspective by reviewing what is currently 
known about its practical application and its 
effectiveness in altering the course and manifes- 
tations of chronic respiratory insufficiency. 

Numerous problems remain. We still do not know 
how many ventilator-dependent patients there are. 
Such data are important both for research and for 
improved communication among investigators, 
caregivers, and patients. Paying for LTMV remains 



a formidable problem, both for the health care 
system and for individual patients and their families, 
and for most patients the logistics of successful home 
care are far more complicated than they should be. 
There is still a critical shortage of beds for ventilator- 
dependent patients in hospitals and in skilled nursing 
facilities. The equipment available for LTMV is 
often unnecessarily complicated, and poses other 
problems for patients and caregivers. One can only 
hope that a third series of special articles in another 
5 years will be able to describe the satisfactory 
resolution of these problems, and at the same time 
bring exciting new information that will be of real 
benefit to those whose health care includes LTMV. 



REFERENCES 

1. Continuing care of the ventilator-dependent patient, 
(special issue) Respir Care 1986;31:266-337. 

2. Pierson DJ, George RB. Mechanical ventilation in the 
home: Possibilities and prerequisites. Respir Care 
1986;31:266-270. 

3. AARC Medicaid Reimbursement Project. Dallas: 
American Association for Respiratory Care, November 
1989. 

4. Stoller JK. Establishing clinical unweanability. Respir 
Care 1991;36:186-198. 

5. Nochomovitz ML, Montenegro HD, Parran S, Daly B. 
Placement alternatives for ventilator-dependent patients 
outside the intensive care unit. Respir Care 1991;36: 
199-204 

6. Gilmartin ME. Long-term mechanical ventilation: Patient 
selection and discharge planning. Respir Care 
1991;36:205-216. 

7. Stoller JK. Physiologic rationale for resting the ventilatory 
muscles. Respir Care 1991 (in press). 

8. Spearman CB. Ventilators and equipment for part-time 
ventilatory assistance. Respir Care 1991 (in press). 

9. Goldstein RS, Avendano MA. Long-term mechanical 
ventilation as elective therapy: Clinical status and future 
prospects. Respir Care 1991 (in press). 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



185 



Establishing Clinical Unweanability 



James K Stoller MD 



Introduction 

For the respiratory care practitioner working in 
intensive care, establishing clinical unweanability 
is a common challenge, which is posed whenever 
a chronically ventilated patient has recovered 
enough to no longer require hemodynamic support 
and intensive care monitoring but not enough to 
be ventilator-independent. 

Because no precise predictors of unweanability 
are available, this paper examines the available 
literature to develop a strategy for establishing 
clinical unweanability. In developing this strategy, 
the epidemiology of unweanability is considered 
first. Specifically, What is the prevalence of 
unweanable patients in reported series, and how 
many patients are currently estimated to be 
unweanable and, therefore, are ventilated outside 
of intensive care unit settings? The next section 
considers the statistics of negative prediction to 
illustrate how criteria for establishing unweanability 
are best judged. The third section considers available 
weaning predictors, both univariate and multivar- 
iate, highlighting their shortcomings in establishing 
unweanability but proposing a weaning "review of 
systems" based on approaches described in the 
literature. 

The final section of the paper reviews some 
strategies that are promising maneuvers (albeit 



Dr Stoller is Head, Section of Respiratory Therapy, and Staff 
Physician, Department of Pulmonary Disease, The Cleveland 
Clinic Foundation, Cleveland, Ohio. 

A version of this paper was presented by Dr Stoller during 
the Long-Term Mechanical Ventilation Symposium at the 1990 
Annual Meeting of the American Association for Respiratory 
Care in New Orleans, Louisiana. 

Reprints: James K Stoller MD, Department of Pulmonary 
Disease, A90, One Clinic Center, The Cleveland Clinic 
Foundation, Cleveland OH 44195. 



unproven) to enhance weaning success, but that 
when unsuccessful buttress the conclusion that the 
patient is unweanable. 

Epidemiology of Unweanability 

Table 1 reviews several available series that report 
the frequency of unweanable patients. '^ The pooled 
prevalence of unweanable patients in these five 
series (total n = 762) is 4.2%, but this frequency 
must be interpreted cautiously, recognizing that the 
five component series vary greatly in the types of 
patients studied. Specifically, whereas Larca and 
Greenbaum^ considered unweanability among all 
patients admitted to a medical intensive care unit, 
several of the series'^s examined a different patient 
population to determine the rate of unweanability 
(ie, those patients known to be difficult-to-wean 
by virtue of established longstanding mechanical 



Table 1. Studies Reporting the Frequency of Clinical 
Unweanability 

Patient 
Author (Date) n Characteristics Unweanable 



Sivak (1980)1 



Larca & Greenbaum 
(1982)2 

Morganroth et al 
(1984)3 



15 



573 



Respiratory 
failure, on MV 
>14d 

All MICU 
admissions 



20% 



1% 



1 1 COPD, on MV 
>30d 



Pardee etal (1984)" 133 Respiratory 

failure, medical 
& surgical ICU 

Aldrichetal (1989)5 30 Respiratory 

failure, deemed 

unweanable 

Total (Pooled) 762 



37% 



4.2% 



186 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



ESTABLISHING CLINICAL UNWEANABILITY 



ventilation). If only the three series of difficult-to- 
wean patients are considered, the frequency of 
clinical unweanability is higher (pooled prevalence 
28.6%), though the number of pooled patients 
considered is smaller (n = 56). Although the 
prevalence of unweanable patients varies with the 
profile of patients being weaned, the clinical 
observation that most patients who are easily weaned 
are weaned within a week of intubation* and that 
many of those not weaned early will experience 
prolonged (and perhaps indefinite) durations of 
ventilatory support underscores the importance of 
having a systematic approach to establishing 
unweanability. 

Estimates of the total number of ventilator- 
dependent patients in the United States suggest that 
between 6,500 and 10,000 patients are currently 
chronically ventilator-dependent.*'' Perhaps the best 
available estimates come from a survey of facilities 
caring for chronically ventilated patients in 
Massachusetts.'' In polling these institutions. Make 
and colleagues identified 147 chronic ventilator 
patients in Massachusetts, of whom 62% were in 
acute care hospitals, 24% were in chronic care 
facilities, and 14% were at home. Leading causes 
of chronic ventilator dependence included chronic 
obstructive pulmonary disease, or COPD (19%), 
amyotrophic lateral sclerosis (12%), peripheral 
neuromuscular disease (12%), and central nervous 
system disease (8%). Based on this survey, the 
estimated prevalence of chronic ventilator- 
dependent patients is 2.8 per 100,000, or 6,573 
chronic ventilator patients in the United States. 





Abbreviations Used in this Paper 


COPD 


— Chronic obstructive pulmonary 




disease 


MIP 


— Maximal inspiratory pressure 


MV 


— Mechanical ventilation 


MVV 


— Maximal voluntary ventilation 


O2COB 


— Oxygen cost of breathing 


PaOj/Fio, 


— Ratio of arterial oxygen tension to 




inspired oxygen concentration 


P0.1 


— Mouth occlusion pressure 


TTdi 


— Tension time index 


VC 


— Vital capacity 


Vd/Vj 


— Dead space-tidal volume ratio 


Ve 


— Minute ventilation 


Vt 


-^ Tidal volume 


woe 


— Work of breathing 



cited, the sensitivity of the weaning predictor (ie, 
of those who actually wean, how many were 
predicted to wean, or a/a + c?) is perhaps the least 
applicable to clinical decision making. Because the 
denominator of the sensitivity expression consists 
of patients who actually weaned (a + c), sensitivity 
presupposes knowledge of the very outcome (ie, 
weanability) that the parameter is intended to 
predict. More clinically germane are the positive 
and negative predictive values, the latter of which 
asks the question: Of those patients predicted not 
to wean on the basis of a weaning parameter, how 
many actually fail to wean? This is the question 
that the clinician poses when attempting to establish 



The Statistics of Negative Prediction 

Figure 1 presents a 2 x 2 table, which is a standard 
tool by which the diagnostic (or predictive) 
performance of a test (or predictor) is evaluated.^ 
When one assembles a 2x2 table for evaluating 
a weaning predictor, patients are placed in one of 
four cells: those predicted to wean who actually 
weaned (Cell a), those predicted to wean who could 
not be weaned (Cell b), those not predicted to wean 
who did actually wean (Cell c), and those predicted 
not to wean who did not wean (Cell d). Four 
summary statistics— sensitivity, specificity, positive 
predictive value, and negative predictive value — 
can be derived from the 2 x 2 table. Though widely 





Yes 




Actually weaned? 
Yes No 




Predicted to 
wean? 


- 


a - b 


; 



No 



Fig. 1.2x2 table for predicting weaning status and summary 
statistics: sensitivity, specificity, positive and negative 



predictive values. Sensitivity 



specificity = ■ 



itive predictive value 
live value = ;r4^. 



j-pg, and negative 



Td- Pos- 
predic- 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



187 



ESTABLISHING CLINICAL UNWEANABILITY 



Table 2. Proposed Univariate Predictors of Weanability 

Lung mechanics and work 
Vital capacity > 10 mL/kg 
Tidal volume > 300 mL 
Respiratory rate < 25/min 
Vd/Vt < 0.60 

Minute ventilation < 10 L/min 
Maximal voluntary ventilation (MVV) > 2 \^ 
Dynamic compliance > 25 mL/cm HiO 
Work of breathing < 1 .8 kg • m • min-' 
Oxygen cost of breathing < 15% of Vq, 

Respiratory muscle strength 

Maximal inspiratory pressure (MIP) > 30 cm H2O 

Respiratory drive 
Po.i < 6 cm H2O 

Gas exchange 

P(A-a)02 "^ 350 torr on Fjo, of I.O 

Pa02/Fl02>238 
PaO2/PAO2>0.47 



clinical unweanability, and weaning parameters that 
help to establish unweanability should have high 
negative predictive values. Because a statistical 
property of both positive and negative predictive 
values is that they may vary with the prevalence 
of the outcome (ie, weaning success or failure) in 
the population under study, parameters with high 
negative predictive values will be more credible to 
the extent they derive from studies in which the 
prevalence of unweanability is low. Specifically, 



in a series or clinical practice where most patients 
are unweanable, achieving a high negative 
predictive value is easy because almost any predictor 
(of unweanability) common to the unweanable 
majority of patients will show a high negative 
predictive value (including such nonsensical 
predictors as having ten fingers). However, because 
unweanable patients comprise only a minority of 
patients in available series (=s 37%, Table 1), criteria 
achieving a high negative predictive value in these 
series are better discriminators of unweanability and 
are therefore deemed more clinically useful. 

Predictive Performance of 
Available Univariate Weaning Predictors 

Table 2 summarizes the univariate predictors of 
weanability that have been proposed. As shown, 
many predictors reflect aspects of lung mechanics — 
respiratory muscle strength, respiratory drive, and 
work of breathing (WOB) and oxygen cost of 
breathing (O2COB). Finally, gas exchange parame- 
ters and the ratio of arterial oxygen tension to 
inspired oxygen concentration (Pa02/Fi02) have been 
proposed. Tables 3-5 review the predictive 
performance of selected univariate weaning 
predictors: minute ventilation (Vg) < 10 L/min, 
vital capacity (VC) > 10-17 mL/kg of body weight, 
and maximal inspiratory pressure (MIP) > 30 cm 
H20.^"''* A review of the performance of these three 
predictors, reported in several studies, suggests: 



Table 3. Minute Ventilation (Vg) < 10 L/min as a Univariate Weaning Predictor 











Prediction Performance 


Study (Date) 


n 


Sensitivity 

(%) 


Specificity 

(%) 


Positive 
Predictive 
Value (%) 


Negative 
Predictive 

Value (%) 


Sahn & Lakshminarayan ( 1973)«* 


100 


92 


100 


100 


71 


Tahvanainen et al (1983)'" 


47 


45 


78 


89 


25 


Kriegeretal(1989)'it 


269 


NS| 


NS 


93 


15 


Yang & Tobin (1989)'2 


41 


24 


69 


55 


37 



*\fe < 10 L/min, MIP > 30 cm H2O, and MVV > 2 Vg. 
tVE < 10 L/min and MIP > 30 cm HjO. 
INS = not stated. 



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Table 4. Vital Capacity (VC) as a Univariate Weaning Predictor 





Criterion 


n 


Sensitivity 

(%) 


Specificity 

(%) 


Prediction Performance 


Study (Date) 


Positive Predictive 
Value (%) 


Negative Predictive 
Value (%) 


Millbemetal (1978)13* 
Tahvanainen et al (IQSa)'" 
Pardee etal(1984)<t 


VC> 15 mL/kg 
VC> 10 mL/kg 
VC> 17 mL/kg 

> 25 cm HjO. 


33 

47 

133 


25 
97 
90 



13 
60 


58 
83 
88 



50 

NSt 


*VC > 15 mL/kg and MIP 
tNS = not stated. 





Table 5. Maximal Inspiratory Pressure (MIP) > 30 cm HjO as a Univariate Weaning Predictor 





n 
100 


Patient Type 


Sensitivity 

(%) 


Specificity 

(%) 


Prediction Performance 


Study (Date) 


Positive Predictive 
Value (%) 


Negative Predictive 
Value (%) 


Sahn & Lakshminarayan (1973)'* 


mean MV 37 h 


92 


100 


100 


71 


Millbem et al (1978)i3t 


33 


mean MV 37 h 


25 





58 





Tahvanainen et al (1983)io 


47 


mean MV 5 d 


68 





74 





DeHavenetal(1986)i'' 


48 


mean MV 55 h 


49 


100 


100 


12 


Kriegeretal(1989)" 


269 


mean age > 70 y, 
MV71 h 


NS 


NSt 


92 


21 



Yang & Tobin (1989) '2 



41 



NS 



76 



25 



61 



40 



*MIP > 30 cm H2O, Ve < 10 L/min, and MVV & 2 Vg. 
tMIP > 25 cm H2O, VC > 15 mL/kg. 
tNS = not stated. 



Table 6. How Long To Wean the Difficult-To-Wean Patient? 



Study (Date) 



Mean Days on 
Ventilator 
No. Weaned (%) (Range) 



Larca & Greenbaum (1982)2 
Morganroth et al (1984)3 
Aldrichetal (1989)5 



8(57%)* 29(11-78) 

9 (82%) 55.8 (30-100) 

12(40%) 52(21-196) 



'-. *0f those deemed difficult to wean. 



(1) With the possible exception of the study by 
Sahn and Lakshminarayan,^ the negative predictive 
values for all three parameters in all available studies 
are low (±50%). (2) Although the higher positive 
predictive values have appeal as predictors of 
weanability, the low negative predictive values 
suggest little usefulness as predictors of unwean- 
ability. (3) None of the studies^''' considers the 
difficult-to-wean patient, for whom accurate 
predictors of unweanability are most needed. 

Specifically, in the series by Sahn and Laksh- 
minarayan^ with the highest available negative 



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ESTABLISHING CLINICAL UNWEANABILITY 



Table 7. Estimates of Pulmonary Component of Resting Work of Breathing 




Mean Work of Breathing 


Author (Date) Normal (at rest) Emphysema Obesity 


Kyphoscoliosis 



Mcllroy & Christie 
(1954)15 

Bergofsky et al (1959)'* 
Fritts et al (1959)i7 
Otis (1964)18 
Sharp et al (1964)1' 



0.034 kg -m-L-i 
0.29kg-m-min-i 

0.051 kg -m-L-' 
0.31 kg-m-min-i 
<0.05kg-m-L-i 
0.035 kg-m-L-i 



0.065 kg -m-L-i 



0.8 kg-m-min- 



0.64 kg • m • min- 



0.063 kg- m-L- 



Table 8. Oxygen Cost of Breathing (O2COB) in Normal Sub- 
jects at Rest and in Subjects with Asthma and Em- 
physema at Rest and with Hyperventilation 



Mean O2COB* 



Author 

(Year) 



Normals 
(rest) 



Asthma Emphysema 



Chemiack(1959)'° 


1.16 


Campbell etal (1959)" 


0.35 


McGregor & Becklake 




(1961)''t 


2.23 


Harden etal (1961)" 


2.96 



6.68 



5.96 



31.85 



*mL Oj/L resting ventilation, 
tunobstructed hyperventilation. 



predictive value (71%), the mean duration of 
mechanical ventilation was 37 hours, with a 
maximal duration of 6 days, unlike the prolonged 
duration of mechanical ventilation seen in most 
series examining difficult-to-wean patients (Table 
6) 2,3,5 Univariate weaning predictors regarding 
work of breathing (WOB) and the oxygen cost of 
breathing (OjCOB) have received attention recently 
because ventilator dependency has come to be 
recognized as the final common pathway of 
ventilatory muscle fatigue. As shown in Table 7,'5-'9 
available estimates of the resting WOB (pulmonary 
component) cluster around 0.3 kg • m • min-', with 
a range from 0.29 kg • m • min-' to 0.33 
kg • m • min-'. As also shown in this table, resting 
estimates of WOB in emphysema and kyphoscoliosis, 
both conditions that may be associated with difficulty 
in weaning, are increased approximately 1.5 to 3- 



Table 9. Transpulmonary Work of Breathing as a Predictor of 
Nonweanability 

Study (Year) n Threshold Value Comment 

Peters et al 
(1972)'" 55 1.80kg -m-min' — 



Proctor et al 

(1973)" 168 



Henning et al 

(1977)'" 28 



Fiastro et al 
(1988)" 17 



Brochard et £d 
(1989)'" 



1.34 kg • m • min' 



1.70 kg • m • min' 



1.60kg • m • min' 



0.8 kg ■ m • min-i 



13.8% false 
positive & 
negative 
rate with 
this cutoff 



Mean value 
for patients 
ventilated 
>24h 



Better 

discriminator 
than VC, Yj, 
MIP,\fe 



fold. The O2COB is a manifestation of respiratory 
muscle work, which includes the isometric com- 
ponent of muscle contraction not measured by WOB 
estimates (which integrate the area under the 
pressure-volume curve). As such, O2COB may be 
a more accurate indicator of muscle energy 
expenditure and efficiency. As shown in Table 8,20-23 



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ESTABLISHING CLINICAL UNWEANABILITY 



available estimates of normal resting O2COB range 
from 0.35 to 2.96 mL of oxygen/L of resting Vg. 
At a Ve of 6 L/min, these estimates translate to 
7 to 18 mL of oxygen consumed by the respiratory 
muscles per minute, or approximately 2% to 7% 
of the total resting oxygen consumption (X),)- As 
also shown in this table, resting O2COB is increased 
as much as 5-fold in emphysema. With hyperven- 
tilation (simulated exercise) O2COB can be 
increased 1 5 -fold above resting levels in normal 
subjects. This is evidence of the mechanical 
disadvantage caused by hyperinflation and the 
lowered efficiency of respiratory muscles in 
obstructive lung disease. 

Based on these considerations, several investi- 
gators have examined the diagnostic value of WOB 
as a predictor of weanability (Table 9). 24-28 Although 
the threshold values for weaning cluster between 
0.8 kg • m • min-i and 1.8 kg • m • min-' (8 to 18 
J/min), the available reports do not permit a close 
analysis of the negative predictive values associated 
with these 'cut points.' Only the study by Fiastro 
et aP^ compares the predictive performance of WOB 
with other univariate parameters (eg, VC, Vp, MIP). 
In this study of 17 patients with respiratory failure 
due to parenchymal disease (only 6 of whom were 
on mechanical ventilation for longer than 4 days). 



ultimate weaning success occurred only when 
transpulmonary work fell below 1.6 kg • m • min-' 
and 0.14 kg • m • L-' of Vg. In contrast, none of 
the more traditional univariate weaning predictors 
distinguished between weaning success and failure. 
Despite these tantalizing findings in the study by 
Fiastro et al,^^ several impediments to adopting 
transpulmonary WOB as a predictor of unwean- 
ability remain: (1) the limited number of available 
studies, (2) the lack of hypothesis-validating studies, 
(3) the persisting lack of information regarding the 
predictive performance in chronically ventilated 
patients, and (4) the unavailability of WOB esti- 
mates in routine clinical intensive care. Although 
future investigation may overcome these current 
shortcomings, at present WOB must be considered 
only a promising predictor of unweanability. 

As reviewed in Table 10,29-35 O2COB has also 
been examined as a predictor of weanability in seven 
available studies, four of which suggest a relation- 
ship between O2COB and weaning duration or 
success29.30.32,35 but three do not.3' 33.34 Qf the four 
supportive studies, only that by Shikora and 
colleagues35 proposes a criterion that can be used 
as a cut point to segregate weaning success from 
failure (ie, O2COB ^ 15%ofX)2<^i'""g'"^<^hanical 
ventilation). However, despite initial appeal, closer 



Table 10. Oxygen Cost of Breathing (O2COB) as a Predictor of Weanability 



Study (Year) 


n 


Patient Type 


MV Time 


COB Useful?/Comment 


Nishimuraetal(1984)-' 


11 


Cardiothoracic surgery 


NS* 


Yes, 0,COB higher in nonweaners 
(20.6% vs 7.8%),t p < 0.05 


HarpinetaKlQS?)'" 


20 


Mixed (COPD in 9) 


16.4 d (mean) 


Yes, linear correlation with days to wean 


Kemper etal (1987)'' 


35 


All postoperative 


8.1 d(mean) 


No, O2COB did not distinguish non- 
weaners 


McDonald etal (1988)" 


30 


Mixed (COPD in 11) 


l-60d 


Yes, nonlinear correlation with days to 
wean 


Hubniayretal(1988)" 


10 


Mixed (COPD in 2) 


1 to > 30 d 


No, OjCOB did not distinguish non- 
weaners 


Annatetal(1990)" 


9 


COPD exacerbation 


3 d (mean) 


No, no correlation with days to wean 


Shikora etal (1990)" 


20 
imption. 


18 Surgical, no COPD 


All > 1 1 d 


Yes, O2COB > 15%t predicts unweana- 
bility 


*NS = not stated. 
tPercent of resting O, const 





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191 



ESTABLISHING CLINICAL UNWEANABILITY 



Weaned within 2 weeks? (as analyzed) 



(a) 



Yes 



No 



WOB 



< 15% 



> 15% 





5 




3 1 


|(a) 




(b) 











12 1 


|(c) 




(d) 





(b) 



5 15 

Ever weaned ? 

Yes 



12 



20 



No 



WOB 



< 15% 



> 15% 





6 




2 1 


|(a) 




(b) 






8 




^ 1 


j(c) 




(d) 





14 



12 



20 



Fig. 2. 2 X 2 tables analyzing data from Reference 35. 
Figure 2a considers the weaning outcome as weaned 
within 2 weeks of study onset (as specified in the study), 
whereas Figure 2b considers the weaning outcome as 
'ever weaned.' Note that because 9 patients were 
eventually weaned later than 2 weeks following the study 
onset, the sums of Cells a and c differ in these two 
analyses, with resultant differences in the predictive 
values. For Fig. 2a negative predictive value = 75%. For 
Fig. 2b negative predictive value = 33%. 



scrutiny of this study suggests shortcomings with 
O2COB as a predictor of unweanability. Specifi- 
cally, Shikora and colleagues^s examined 20 
consecutive, stable, ventilator-dependent (5=11 
days) patients, of whom 18 were ventilated post- 
operatively. O2COB was determined as the dif- 
ference between oxygen consumption during total 
ventilatory support and that during spontaneous 
breathing. Weaning failure in this trial was defined 
as the persistence of ventilator dependence 2 weeks 
after initiating the study, and 15 of the 20 study 
participants were considered weaning failures by 
this criterion. Figure 2a presents the study data in 
a 2 X 2 table to elucidate the predictive performance 
of the O2COB. Notably, the negative predictive 



value of 100% (based on the emptiness of Cell' c 
[patients with an O2COB > 15% but successfully 
weaned within 2 weeks]) is appealing, but 
reconsideration of the data according to whether 
patients were ever weaned (vs weaned within 2 
weeks of study onset) suggests a different 
conclusion. Specifically, Figure 2b re-analyzes the 
data using a definition of successful weaning as 
"ever weaned." With this rendition of the data. 
Cell c of the 2 X 2 table contains 8 patients who 
were ultimately successfully weaned, albeit later 
than the 2-week window proposed by the first 
criterion of weaning failure. In this second analysis, 
the negative predictive value of O2COB ^ 15% of 
Vq, during mechanical ventilation falls to 33%, 
suggesting less usefulness of this parameter as a 
criterion of unweanability. Overall, as with WOB, 
O2COB shows several limitations as a weaning 
predictor: 

1 . Conclusions from available studies are mixed. 

2. The negative predictive value of this criterion 
is low, even in the most supportive series. 

3. A useful cut point for cost of breathing is 
not currently available. 

4. The O2COB is not routinely available in 
intensive care units. 

In summary, because of low negative predictive 
values, available studies fail to provide a useful 
univariate predictor of unweanability. Not surpris- 
ingly, strict adherence to available univariate 
predictors with low negative predictive values can 
delay weaning. For example, Krieger and col- 
leagues" estimated that dependence on MIP and 
Ve as weaning predictors would have delayed 
weaning in 99 of 241 (41%) successfully weaned 
patients in their series. The inadequate predictive 
performance of univariate parameters suggests that 
the need for mechanical ventilation is a complex 
phenomenon and is, therefore, more likely to be 
successfully summarized by accounting for at least 
several variables rather than just one.^^^-^^ 

Available Multivariate Predictors of Weanability 

Recognizing the severe limitations of univariate 
weaning parameters, several investigators (Table 
1 1 ) have evaluated the predictive performance of 
multivariate indexes to predict weanabil- 



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ESTABLISHING CLINICAL UNWEANABILITY 



ity. 3,9, 1 1,12,39,40 As showM ill Table 1 1, the complexity 
of these multivariate indexes varies. The simplest 
includes just two parameters (MIP and Vg)," and 

Table 1 L Multivariate Indexes To Predict Weanability 



the most complex incorporates a large number of 
clinical features.^ Table 12 reviews the predictive 
performance of these multivariate indexes and 



Author (Year) 



Index 



Components (n) 



Patients Examined 



Sahn & Lakshminarayan (1973)' 
Hilberman et al (1976)" 
Morganroth el al (1984)^ 

Higginsetal(1988)'" 

Kriegeretal (1989)" 
Yang &Tobin (1989)" 



Satisfy all 3 criteria 

Nurses' assessments 

Adverse Factor Scored; 
Ventilator Scored 

Ventilator Dependency 
Scoreif 

Satisfy both criteria 

CROP' 



MIP, \e, MVV (3)* 
NSt 

Heart, lung, nutrition (21) 
F102, f, compliance (6) 

Compliance, Fio: heart, 
bilirubin, creatinine (9) 

MIP and \fe (2) 

Compliance, rate, 
oxygenation, pressure (4) 



1 00 patients, mean time on MV 37 h 
125 open heart surgery patients 
1 1 COPD patients, MV > 30 d 

29 open heart patients, MV > 48 h 

269 patients > 70 y, mean MV 71 h 
41 patients, unspecified 



*MIP = maximum inspiratory pressure; \fe = minute ventilation; MVV = maximal voluntary ventilation; MV = mechanical ventila- 
tion; f = frequency; COPD = chronic obstructive pulmonary disease; CROP = compliance, rate, oxygenation, & pressure. 
tNS = not specified. 
|See text. 

Table 12. Summary of Available Multivariate Indexes for Weaning Prediction 

Predictive Value 



Study (Year) 



Index 



Patient Type 



Positive 
Prediction 

(%) 



Negative 
Prediction 

(%) 



Sahn & Lakshminarayan 

( 1 973)" 1 00 MIP >30 cm H2O, \fe < 1 OL/min, inixed 

and MVV > 2 \fe 

Hilberman et al (1976)"' 124 Nurses' assessments 



100 



71 



Kriegeretal (1984)' 



269 MIP > 30 cm H2O,* 
\fe < 10 L/min 



Morganroth et al (1984)' II Adverse Factor Score t 

Ventilator Scoret 

Higgins et al ( 1 988)* 29 Ventilator Dependence 

Yang&Tobin (1989)" 41 'CROP' Score§ 



open heart surgery 


82 


67 


> 70 y, mean time on MV 7 1 h 


93 


15 


COPD, MV > 30 d 


73 


m 


open heart surgery. 


NS 


NSt 



MV > 48 h 



NS 



87 



72 



*MIP = maximum inspiratory pressure; \fe = minute ventilation; MV = mechanical ventilation; COPD = chronic obstructive pulmo- 
nary disease; MVV = maximal voluntary ventilation; NS = not stated. 
tSee text and Table 1 3. 

IHypothesis-generating study not confirmed in separate data set. 
§See Table 12. 



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ESTABLISHING CLINICAL UNWEANABILITY 



Table 13. Components of the Adverse Factor and Ventilator 
Scores of Morganroth et al' 

Adverse Factor Score (total points assigned = 48) 
Hemodynamics & vital signs 

Heart rate (0-3) 

Blood pressure (0-5) 

Temjjerature (0-3) 

Central venous pressure (0-2) 

Arrhythmia, by type ( 1 -4) 

Vasopressors needed? (0-2) 

Presence of infection 
Oral antibiotics needed? (0-1) 
Parenteral antibiotics needed? (0-2) 

Nutrition 
Calories/24 h (0-2) 

Neurologic/psychiatric state 
Level of consciousness (0-4) 
Communication (0-4) 
Mobility (0-1) 
Emotional status (0-2) 
Sedatives needed? (0-3) 
Pain medications needed? (0-3) 



Ventilator Score (total points assigned 
Fraction inspired oxygen (0-4) 
Level of PEEP (0-10) 
Static complicance (0-4) 
Dynamic compliiance (0-3) 
Ventilator minute volume (0-5) 
Triggered respiratory rate (0- 1 ) 



27) 



shows that the negative predictive values are 
generally higher than those reported with univariate 
predictors.-'"'^"''''*" That comprehensive clinical 
assessment can help predict unweanability is 
suggested in a study by Hilberman et al.^^ Nurses' 
weaning predictions based on a clinical gestalt 
of 124 patients following open heart surgery 
demonstrated a negative predictive value of 67%, 
somewhat higher than most of the univariate 
predictors available (Tables 3-5). On the other hand, 
the impact of this study is limited by the fact that 
the patients were generally short-term ventilator 
patients. Similarly, most of the multivariate studies 
that characterize patients have examined patients 
mechanically ventilated for a short term, again 
limiting the generalizability of these study 
conclusions for predicting unweanability among 
long-term mechanically ventilated patients. One 
exception is the study by Morganroth et al,^ which 



considered only patients on mechanical ventilators 
for at least 30 days. Examining 1 1 patients with 
COPD, these investigators found that VC and MIP 
failed to distinguish the 9 successfully weaned 
patients from the other 2 who remained unweanable. 
However, in a post-hoc analysis, Morganroth et al 
did find that better prediction of weaning failure 
could be made using a multivariate system (the 
Adverse Factor Score and the Ventilator Score). 
Components of these scores are listed in Table 13, 
with points assigned for increasing degrees of 
physiologic derangement. Recipients of a score 
exceeding 55 (out of a total 75 points for the sum 
of the Adverse Factor and Ventilator Score) were 
less likely to wean successfully. Despite the study's 
limitations — (1) it considers only a small number 
of patients, each of whom received multiple score 
determinations; (2) it is hypothesis-generating only, 
without validation of the predictive performance of 
the Adverse Factor and Ventilator Scores in a 
separate validation data set; and (3) its actual scoring 
system is cumbersome for routine clinical use — 
the high negative predictive value (97%) for scores 
exceeding 55 is compelling. Combined with data 
on nurses' assessments by Hilberman et al"*^ the 
impact of this study is to emphasize that the 
decisions regarding unweanability can best be made 
by assessing multiple clinical features, many of 
which are cited in the Adverse Factor and Ventilator 
Scores. 

Overall, because of the inadequate negative 
predictive value of available univariate predictors 
and the unvalidated performance of the more 

Table 14. Review of Systems: Key Factors To Consider Prior 
to Weaning 

Patient Features 

Hemodynamic stability? 

Control of infection? 

Adequate oxygenation? 

Optimized control of secretions and 
bronchospasm? 

Preserved drive to breathe? 

Psychologically ready to wean? 

Optimized nutrition? 

Optimized respiratory muscle function and 
endurance? 
Features of the patient-ventilator interface 

Minimized ventilator-imposed work of breathing? 

Maximized endotracheal-tube size? 

Inspiratory flow demands met? 

Minimized auto-PEEP? 



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ESTABLISHING CLINICAL UNWEANABILITY 



promising multivariate indexes, current assessment 
of unweanabiiity cannot depend entirely on available 
instruments. 

Rather, it appears that the best available current 
strategy to establish unweanabiiity is to review 
remediable aspects of the patient and the ventilator 
system and to optimize the likelihood of successful 
weaning. Unweanabiiity should be deemed to be 
established only after remediable factors to enhance 
weaning have been addressed. Key features 
regarding the patient, the ventilator circuit, and the 
patient-ventilator interface are summarized in a 
review of systems in Table 14. which proposes a 
systematic approach to establishing unweanabiiity. 

Specific Strategies To Enhance Weanability 

The issues of optimizing weaning status and 
minimizing the WOB during mechanical ventilation 
have been recently reviewed extensively. "-^^^i 
Table 15 lists several maneuvers to enhance 
weaning. 

Table 15. Maneuvers To Enhance Weanability 

Optimize nutrition 

Optimize respiratory muscle strength and stamina 

with drugs 

with inspiratory muscle training 
Optimize psychologic readiness 
Minimize imposed work of breathing 

by maximizing endotracheal-tube caliber 

by minimizing auto-PEEP 



As in the review of systems in Table 14, 
maneuvers to enhance weanability can be classified 
into clinical features of the patient that affect 
weanability and features of the ventilator-patient 
interface that affect weanability. 

In considering selected maneuvers, accumulating 
data suggest that nutritional repletion is an important 
aspect of optimizing weanability.^ 42-44 Several lines 
of evidence support this concept: (1) Malnutrition 
causes decreased respiratory muscle strength and 
endurance,"^ (2) nutritional repletion of malnour- 
ished COPD patients can enhance respiratory muscle 
strength and endurance,''^'" and (3) in uncontrolled 
series, a response to nutritional repletion is 
associated with enhanced weanability. 2-42 

The most optimistic reports available demonstrate 
the favorable effects of refeeding. Specifically, 
Whittaker and colleagues44 have recently conducted 



a randomized, double-blind, controlled trial in 10 
malnourished (< 85% ideal body weight) patients 
with COPD. Six patients were allocated to a 
refeeding regimen consisting of > 1 ,000 kcal above 
usual intake, given as an enteral formula (Isocal, 
Mead Johnson, Evansville IN) while four patients 
in the control group were maintained on their usual 
diet (>100 kcal above usual intake) over the mean 
6-day study period. Refed patients demonstrated 
greater weight gain (mean 2.4 kg increase) and with 
significant increases in maximal expiratory pressure 
and in mean sustained inspiratory pressure, a 
measure of respiratory muscle endurance. 

Although no prospective, randomized trials are 
available to establish the efficacy of refeeding to 
enhance weanability, supportive evidence comes 
from two observational studies. In a retrospective 
observational cohort study, Bassili and Deitel'*2 
showed that among patients ventilated for ^ 3 days, 
recipients of nutritional support (8,300-12,600 kJ/ 
day) had a higher rate of weaning (92.8%) than 
a non-alimented (1,650 kJ/day) comparison group 
(54.5% weaning success). In a subsequent case- 
control study, Larca and Greenbaum^ observed that 
in a group of ventilator-dependent patients on 
comparable nutritional regimens, those who failed 
to wean were less likely to show improvement in 
nutritional parameters (eg, albumin and transferrin 
levels) than those successfully weaned. Though 
neither of these studies establishes the efficacy of 
nutritional repletion for enhancing unweanabiiity, 
the weight of clinical evidence suggests that 
unweanabiiity cannot be established until nutritional 
repletion has been undertaken. Unfortunately, 
available studies do not establish nutritional target 
parameters for establishing unweanabiiity. How- 
ever, evidence suggests that improvement in 
respiratory muscle function and endurance can be 

Other promising strategies to optimize respiratory 
muscle strength and endurance and thus to enhance 
the patient's candidacy to wean include adminis- 
tering drugs to enhance respiratory muscle strength 
and endurance^s (eg, methylxanthines'"''*? and 
sympathomimetics48-49)^ and, in select instances, 
training the inspiratory muscles by inspiratory 
resistive exercises. ■''■^o In the absence of controlled 
trials, neither strategy can be strongly endorsed, but 
favorable experience in uncontrolled series suggests 
that a trial of aminophylline and/or inspiratory 
resistive training may occasionally be warranted 
before considering a patient to be unweanable. 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



195 



ESTABLISHING CLINICAL UNWEANABILITY 



resistive training may occasionally be warranted 
before considering a patient to be unweanable. 

Finally, the patient's psychologic status is an 
important determinant of weanability. Though 
infrequently given specific attention (perhaps 
because psychologic readiness is difficult to measure 
and modify), behavioral and psychologic maneuvers 
can enhance weanability and should be exercised 
before unweanability is considered established. 
Following scattered reports suggesting enhanced 
weaning by hypnosis^'-''^ and biofeedback,''^ a recent 
randomized trial suggests that biofeedback can 
accelerate weaning in difficult-to-wean patients.-''^ 
Forty awake ICU patients ventilated for > 7 days 
were randomly allocated to receive biofeedback (ie, 
reassurance plus reinforcement for adequate tidal 
volume and maximizing relaxation) or control 
(reassurance alone) maneuvers. Though the 
compared groups were similar at baseline for 
APACHE II scores and MIP, biofeedback recipients 
weaned significantly faster than control patients 
(20.6 ± 8.9 days vs 32.6 ± 17.6 days, p < 0.01) 
and showed greater and more efficient tidal volumes 
during weaning. These results establish biofeedback 
and reassurance as additional useful maneuvers for 
enhancing weanability. Psychologic readiness 
should be optimized before unweanability can be 
considered established. 

In addition to optimizing patient features to 
enhance weanability, minimizing WOB imposed by 
the ventilator circuit and ventilatory strategy can 
also aid weaning. Remediable aspects of the 
ventilator-patient interface include maximizing the 
caliber of the endotracheal tube, assuring that the 
patient's inspiratory flow demands are met by the 
ventilator, and, in the setting of obstructive airways 
disease, assuring that auto-PEEP is minimized. 

To the extent that the endotracheal tube may 
impose increased WOB^"* and that imposed WOB 
falls as the diameter of the endotracheal tube 
increases, provision of an endotracheal tube of the 
maximum feasible diameter is advised before 
unweanability can be considered established.^'' The 
detrimental impact of small endotracheal tube 
caliber has been demonstrated by Shapiro et al in 
a lung model system.^'' As shown in Figure 3, the 
tension-time index (TT^i) approaches the fatiguing 
threshold of 0.15 when V^ reaches high levels 
through small (eg, 6-mm) endotracheal tubes. The 
observation that imposed WOB in vivo exceeds the 



WOB ascribed to the endotracheal tube using a lung 
model underscores the importance of maximizing 
the endotracheal-tube caliber in clinical care.^^ 
Tubes with inner diameters ^ 8 mm should be used 
whenever technically possible. 

Another source of imposed WOB is auto-PEEP.^'' 
Realization that auto-PEEP can be an inspiratory 
pressure load has fostered interest in using explicit 
PEEP (ie, PEEP that is 'dialed in') to offset the 
inspiratory pressure loading. Two recent studies 
demonstrate that explicit PEEP can diminish the 
WOB imposed by auto-PEEP in patients with 
dynamic hyperinflation and expiratory flow 
limitation.5**-'''^ Studying 10 ventilated patients with 
COPD, Smith and Marini''** showed concomitant 
decreases in auto-PEEP and inspiratory WOB as 
applied PEEP increased from to 10 cm H2O. 
Although the magnitude of the decline in WOB 
varied greatly, features associated with the greatest 
diminution of WOB with applied PEEP were high 

0.2 r 

•— 6 Tube 

7 Tube 

8 Tube 

9 Tube 
0.15|- A-.^OTube 



0.1 



0.05 








j- 



-L. 



O. 



-L 



-L 



J 



5 10 15 20 25 30 



Fig. 



V£ L/min 

3. Relation between tension-time index (TTdi) and 



increasing minute ventilation (Ve) through endotracheal 
tubes of different sizes. With high V^ through small caliber 
endotracheal tubes (6-& 7-mm), TToi approaches the 
fatiguing threshold of 0.15. From Reference 52, with 
permission. 



196 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



ESTABLISHING CLINICAL UNWEANABILITY 



initial WOB and stability of static peak pressure 
with rising levels of applied PEEP. Similar 
observations by Petrof et al""^ underscore considering 
auto-PEEP as a remediable source of imposed WOB 
that should be addressed before considering a COPD 
patient to be unweanable. 

Conclusions 

To the extent that weaning represents a complex 
interaction between the patient and the ventilator 
system, establishing unweanability is not easily 
summarized by a simple rule of thumb. Rather, 
unweanability can only be considered established 
once the patient fails to wean despite optimal 
management to facilitate weaning. 

The foregoing discussion suggests the following 
conclusions: 

• Available parameters are poor predictors of 
unweanability. 

• For long-term ventilated patients, the predictive 
performance of available predictors is even more 
limited. 

• Multivariate indices are more promising, but no 
valid predictor of unweanability is currently 
available. 

• In view of an inability to predict unweanability, 
establishing unweanability is empiric (ie, requires 
showing that the patient cannot wean despite 
optimized candidacy to wean). 

• Until better negative prediction is available, 
optimizing clinical features summarized in the 
patient-ventilator review of systems is a sensible 
approach. 

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39. Hilberman M, Kamm B, Lamy M, Dietrich HP, Martz 
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43. Pingleton SK, Harmon GS. Nutritional management in 
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44. Whittaker JS, Ryan CF, Buckley PA, Road JD. The effects 
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45. Aubier M. Pharmacotherapy of respiratory muscles. Clin 
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46. Moxham J. Aminophylline and the respiratory muscles: 
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47. Viires N, Aubier M, Murciano D, Fleury B, Talamo C, 
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48. Stoller JK, Wiedemann HP, Loke J, Snyder P, Virgulto 
J, Matthay RA. Terbutaline and diaphragm function in 
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49. Aubier M, Murciano D, Menu Y, Boczkowski J, Mai 
H, Pariente R. Dopamine effects on diaphragmatic 
strength during acute respiratory failure in chronic 
obstructive pulmonary disease. Ann Intern Med 
1989:110:17-23. 

50. Aldrich TK, Karpel JP. Inspiratory muscle resistive 
training in respiratory failure. Am Rev Respir Dis 1985; 
131:461-462. 

51. LaRiccia PJ, Katz RH, Peters JW, Atkinson W, Weiss 
T. Biofeedback and hypnosis in weaning from mechanical 
ventilation. Chest 1985;87:267-269. 

52. Corson JA, Grant JL, Moulton DP, Green RL, Dunkel 
PT. Use of biofeedback in weaning paralyzed patients 
from respirators. Chest 1979;76:543-545. 

53. Holliday JE, Hyers TM. The reduction of weaning time 
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141:1214-1220. 

54. Brochard L, Rua F, Lorino H, Lemaire F, Harf A. The 
extra work of breathing due to endotracheal tube is 
abolished during inspiratory pressure support breathing 
(abstract). Am Rev Respir Dis 1988:137(4, Part 2):64A. 

55. Shapiro M, Wilson RK, Cesar G, Bloom K, Teague RB. 
Work of breathing through different sized endotracheal 
tubes. Crit Care Med 1986;14:1028-1031. 

56. Wright PE, Marini JJ, Bernard GR. In vitro versus in 
vivo comparison of endotracheal tube airflow resistance. 
Am Rev Respir Dis 1989;140:10-16. 

57. Pepe PE, Marini JJ. Occult positive end expiratory 
pressure in mechanically ventilated patients with airflow 
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58. Smith TC, Marini JJ. Impact of PEEP on lung mechanics 
and work of breathing in severe airflow obstruction. J 
Appl Physiol 1988;65:1488-1499. 

59. Petrof BJ, Legare M, Goldberg P. Milic-Emili J, Gottfried 
SB. Continuous positive airway pressure reduces work 
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disease. Am Rev Respir Dis 1990;141:281-289. 



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Placement Alternatives for Ventilator-Dependent Patients 
Outside the Intensive Care Unit 

Michael L Nochomovitz MD, Hugo D Montenegro MD, 
Susan Parran MSW, and Barbara Daly RN MSN 



Patient Management and 
Financial Consequences of Prolonged ICU Care 

Advances in medical practice and the increased 
availability of new technology have increased the 
scope of care delivered to critically ill patients in 
the modem intensive care unit (ICU). Munoz et 
al suggest that critical care medicine accounts for 
approximately 15% of hospital costs.' A corollary 
of our ability to prolong life in the ICU, for both 
medical and surgical conditions, is a large number 
of patients dependent on mechanical ventilators for 
a prolonged period of time. 

The introduction of the diagnosis-related-group, 
or DRG, system of reimbursement for hospitalized 
Medicare patients has resulted in institutions' often 
incurring substantial losses from such hospitaliza- 
tions. This reality has resulted in a focus on the 
efficient utilization of these resources and innovative 
experiments for the saving of ICU resources for 
patients most requiring this intensity of care and 
this particular environment for their treatment. 

The Ventilator-Dependent Patient 

The nature of current practice patterns and their 
implication for resource utilization have resulted in 
the refinement of the concept of the ventilator- 
dependent patient. The characterization of the 



Dr Nochomovitz and Dr Montenegro are associated with the 
Pulmonary Treatment Center, Department of Medicine, 
University Hospitals of Cleveland, and the Department of 
Medicine, Case Western Reserve University School of 
Medicine; Ms Parren is associated with the Social Work 
Department, University Hospitals of Cleveland; and Ms Daly 
is associated with the Department of Nursing, University 
Hospitals of Cleveland Francis Payne Bolton School of Nursing, 
Case Western Reserve University — Cleveland, Ohio. 



ventilator-dependent patients has been extended 
beyond the patient destined for lifelong ventilatory 
support. The experience with more than 737 patients 
in the medical intensive care unit at the University 
Hospitals of Cleveland suggests that only one third 
of these patients remain intubated for more than 
1 week (Fig. 1). 




I DAYS 



Fig. 1 . Length of mechanical ventilation for 757 consec- 
utive mechanically ventilated patients in the medical 
intensive care unit of University Hospitals of Cleveland. 



Of the patients requiring intubation and mechan- 
ical ventilation, most are weaned and extubated 
rapidly; however, some require prolonged hospi- 
talization before being weaned from the ventilator 
and discharged from hospital; and a still smaller 
number require chronic ventilation following 
discharge from hospital. 

Chronic ventilator care may take the form of full- 
time mechanical ventilation or more frequently only 
part-time or nighttime assistance. An increasing 
number of patients are utilizing noninvasive 
ventilatory assistance in the form of negative- 
pressure support (cuirass, body suit) or positive- 
pressure nasal ventilation.^-^ Although these patients 



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PLACEMENT FOR VENTILATOR-DEPENDENT PATIENTS 



are not dependent on ventilatory assistance for life 
support, patient and family education and financial 
resources are required to institute and maintain these 
forms of therapy. 

The group requiring permanent tracheostomy and 
positive-pressure ventilation tend to be ventilator 
dependent for life support. They are often the most 
difficult challenges for discharge planning because 
of the financial and social support systems required. 
In addition, these patients may, despite all efforts, 
be unable to return to a home environment and 
require discharge to a chronic care facility, nursing 
home, or alternate community location. ^-^ 

Patients in chronic respiratory failure often may 
have other organ-system diseases that further 
complicate their discharge planning and long-term 
management. Their care necessitates the use of often 
scarce intensive care beds at extremely high cost 
to the third-party payer, the patient, or the institution. 

Managing those ventilator patients who are not 
speedily weaned and extubated requires specific 
skills that are different from those traditionally found 
among intensivists. The patients often require a 
lesser intensity of care with less reliance on high 
technology. The therapeutic intervention is of a more 
rehabilitative nature, and the family or other 
caregivers at home play an important role in 
supporting and encouraging the patient being 
weaned from the ventilator prior to discharge. 

The realization that this process is unique and 
requires a special expertise and environment has 
been bolstered by the financial pressures in health 
care to study our practice patterns and modify our 
strategy. In addition, the paucity of alternatives for 
placement of ventilator-dependent patients has 
resulted in a reevaluation of current traditional sites, 
home ventilation, and consideration of innovative 
alternatives (eg, group residential and foster care). 

Hospital Alternatives to the Intensive Care Unit 

A number of attempts have been made to establish 
intermediate care units to facilitate the management 
and weaning of patients who require less intense 
care but are still ventilator dependent. These have 
been documented to varying degrees since the initial 
description of a respiratory care unit by Petty et 
alin 1971." 

The original respiratory care unit sought to 
differentiate patients who had ventilatory insuffi- 



ciency from other critically ill patients. However, 
the evolution of critical care has been such that 
this appears to be a flawed separation. Although 
patients in surgical, cardiac, neurosurgical, and 
medical intensive care units may normally require 
ventilatory support for short periods of time during 
the acute phase of their illness, a number of these 
patients will enter a more subacute or chronic phase 
of recovery, with care requirements different from 
those available in the conventional ICU setting. 

The appropriateness of caring for such chronic 
patients in the traditional ICU setting has also been 
questioned. A rehabilitative environment rather than 
intensive care is appropriate for many of these 
patients and their critical care beds are needed to 
accommodate patients requiring intensive care. 

Prolonged weaning may also be better accomp- 
lished in a setting in which the patient can be 
reoriented to a conventional sleep cycle and can 
become a participant in the evolution of his care. 
Such an environment may also facilitate family 
participation in the patient's care and recovery. A 
number of models have been proposed, although 
the data supporting their cost-effectiveness or 
superiority, over the traditional environment is not 
yet available. 

Models of Intermediate Care Units 

Noninvasive Monitoring Unit 

The model described by Bone and Balk'" 
emphasizes the use of noninvasive technology for 
monitoring patients and a team approach to patient 
management and weaning. The unit is located on 
a general medical floor, with consequent lower costs. 
The medical director supervises the development 
and execution of the care plan. Medical housestaff 
are assigned to the unit and work with nurses 
assigned in a ratio of 1:3 or 1:4. Noninvasive 
monitoring includes pulse oximetry, capnography, 
and inductive plethysmography. Formal compara- 
tive data relating to the cost-effectiveness of this 
unit have not yet been published. 

Prolonged Respiratory Care Unit 

Indihar and Walker" described a unit for 
prolonged respiratory care staffed by a medical 
director and a team drawn from nursing, respiratory 



200 



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PLACEMENT FOR VENTILATOR-DEPENDENT PATIENTS 



therapy, social work, and the nutrition services. No 
medical house officers are assigned to this unit and 
the reimbursement is arranged with local third-party 
payers to conform to one of four levels of care 
intensity. This reimbursement excludes physician 
and pharmacy costs. The unit is apparently capable 
of managing patients for an indefinite period and 
goes beyond the intermediate care concept; 
however, the identification of patients who could 
be discharged home is emphasized. No formal study 
data are available for evaluation from this unit. 

Special Care Unit 

The special care unit (SCU) model has been 
developed at the University Hospitals of Cleveland 
and is currently being studied within the context 
of a grant to the Frances Payne Bolton School of 
Nursing and the Nursing Department of the 
University Hospitals of Cleveland. '2 

The unit was opened in May 1989 and is 
structured around an experienced group of nurse 
case managers and pulmonary physicians. The 
multidisciplinary team includes a respiratory 
therapist, nutritionist, and social worker. No house 
officers work in the SCU, but the various medical 
and surgical consultants frequently interact via the 
nurse case managers. 

Patients are housed in single patient rooms in 
the dedicated physical plant. The daily schedule is 
designed to foster recovery of normal orientation 
and sleep patterns and family involvement. High 
technology is restricted, and noninvasive techniques 
(eg, oximetry, inductive plethysmography, and 
bedside echocardiography) are routinely utilized. 

Following a week in one of the conventional units 
(medical or surgical), ventilator patients are 
randomized to the study. Patients may be controls 
(ie, remain in ICU receiving conventional therapy) 
or study subjects (ie, be transferred to the special 
care unit). Severity of illness is controlled for across 
the two groups by APACHE and TISS scores. No 
hemodynamic monitoring is employed. 

Preliminary study suggests that outcome is no 
worse for the SCU patients, with a tendency for 
fewer tests to be performed. Some evidence suggests 
that this model will be cost-effective from the 
hospital standpoint, though this remains to be 
statistically validated.'^ 



Chronic Ventilation Outside the Hospital 

Home Ventilation 

The majority of patients on chronic mechanical 
ventilation in the United States reside in their homes. 
Although this is clearly advantageous for many 
patients, it also reflects the lack of alternate sites. '-^ 

The decision to discharge a patient home depends 
on the presence of: 

• a diagnosis amenable to home ventilation, 

• clinical stability and a manageable care routine, 

• an appropriate physical environment, 

• qualified caregivers, 

• financial resources necessary to meet recurring 
expenses, and 

• informed consent. 

Home ventilation, a technically feasible treatment 
modality for many patients, has been utilized 
extensively in some centers in the U.S. over the 
last 10 years. The general experience suggests the 
most success with chronic respiratory failure 
secondary to chest-wall deformities (eg, kyphoscoli- 
osis) and neuromuscular disease (eg, Duchennes 
muscular dystrophy).^ Such patients may achieve 
substantial vocational or occupational independ- 
ence. '"* The results in patients with chronic 
obstructive pulmonary disease have been less 
satisfactory, although individual patients may do 
quite well. Persistent sensations of severe dyspnea 
and copious secretions have been discouraging to 
many mechanically ventilated COPD patients. 
COPD candidates for chronic mechanical ventilation 
should be carefully selected. 

Patients should not be discharged on ventilators 
to nonhospital environments before they are 
clinically stable. The challenges of caring for 
ventilator-dependent patients are sufficiently great 
without having to contend with a fluctuating clinical 
course because of other complicating conditions. '^ 
A patient's need for a second complex technology 
(eg, home dialysis) usually precludes care at home. 
However, situations do exist in which additional 
complexities can be successfully introduced. An 
example is phrenic nerve pacing in high quadriplegia. 
Such patients require the presence of a backup 
ventilator in addition to the pacemaker. Patient, 
family, and caregivers are required to be well trained 
in the manipulation of both devices. Outside of a 



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PLACEMENT FOR VENTILATOR-DEPENDENT PATIENTS 



handful of centers with experience managing these 
patients, successful application woridwide has been 
limited."' 

The home environment needs to be suitable to 
accommodate the patient and the necessary 
equipment. A poorly maintained home precludes 
discharge of the patient to the home, and an 
alternative location for placement should be sought. 
A patient usually should not be discharged home 
unless a caregiver will always be available. Coverage 
for aides and nurses vary according to the payer. 
In the case of Medicare, only intennittent nursing 
visits are usually covered. Private payers may 
reimburse for continuous care, but policies are 
usually capped at a level designated by the individual 
policy. Health maintenance organizations (HMOs) 
and other managed care programs have a range of 
benefits that require individual clarification. 
Appropriate patient and caregiver education must 
be provided before the patient's discharge. The 
durable medical equipment required for home 
ventilation is usually covered by third-party payers 
(including Medicare and Medicaid). Disposable 
supplies (eg, tracheostomy tubes and suction 
catheters) are often not covered by third-party payers, 
and the patient needs to be able to cover these 
expenses. Patients are sometimes expected to make 
co-payments on the order of 20% even when 
insurance coverage is available, and the presence 
of this requirement must be clarified at the out.set. 

If clinical, social, and financial conditions lend 
themselves to consideration of home ventilation, the 
patient's informed consent must be obtained before 
the option is pursued further. The patient must be 
made aware of the implications of home ventilation 
in terms of the course of the illness, quality of life, 
and social and financial impact on the family. At 
our institution, we make it clear that choosing 
mechanical ventilation is not an irrevocable decision 
and that long-term mechanical ventilation can under 
appropriate circumstances be discontinued. How- 
ever, in our experience, it is the rare patient who 
will elect to discontinue ventilatory support. 

Respite Care 

Although home care for the patient with 
appropriate resources is clearly ideal, such an 



arrangement results in severe stress on the extended 
family. Social and recreational activities are always 
limited by considerations for the ventilator- 
dependent loved one. Some hospitals and interme- 
diate care facilities make provisions to allow families 
to take vacations or just have physical and emotional 
respite from the burden of chronic care. Such respite 
may be particularly needed during intercurrent 
illness, should be viewed as an integral part of health 
care, and should clearly be recognized under specific 
guidelines by private and public payers. 

Foster Care 

It is possible for persons who are not family 
members to provide home care for ventilator- 
dependent patients. The importance of pursuing the 
possibility of community, rather than institutional, 
care for long-term ventilator patients cannot be 
overemphasized. Precedents for foster care of such 
patients have been established, and this could become 
a more frequently utilized alternative, with formal 
screening of interested parties and regular follow 
up by the funding agency and the attending physician 
caring for the patient. 

Nursing-Home Care 

Stable ventilator-dependent patients for whom 
home care is not feasible may require nursing-home 
placement. However, this alternative is limited 
nationwide by the small number of nursing-home 
beds available for ventilator patients. In many states, 
reimbursement for such care is limited, making the 
care of ventilator patients a financially nonviable 
option for many nursing homes. '^ 

Reimbursement from private payers is often 
capped, thereby limiting long-term coverage. 
Coverage from public sources (eg. Medicare, 
Medicaid) is usually insufficient to adequately cover 
the institution's costs — hence the small number of 
beds available nationwide for this purpose. Although 
states are mandated by the federal government to 
provide nursing-home care for the chronically 
disabled, coverage varies from state to state. In some 
states (eg, California and Delaware) additional 
reimbursement is made to nursing homes for 
ventilator-dependent patients thereby facilitating this 
alternative. However, in some states the nursing- 



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PLACEMENT FOR VENTILATOR-DEPENDENT PATIENTS 



home options are so limited for Medicaid patients 
that cases of out-of-state placement to accommodate 
these patients have been reported. 

An informal survey of acute care hospitals 
conducted in Ohio in August 1990, revealed that 
at least 50 ventilator-dependent patients were waiting 
for nursing-home placement. These patients 
accounted for 4,345 patient days while waiting for 
placement (personal communication, S Parran, 
1990). The economic implications of this situation 
for acute care facilities are obvious. 

Even though funds allocated for nursing-home 
placement are limited and often inadequate, they do 
exist; but such funds are not usually made available 
to cover the provision of caregivers in the home 
or group residential facility. The patient who wishes 
to live outside a nursing home cannot usually obtain 
public funds to cover the cost of caregivers and a 
suitable home environment. However, notable 
exceptions to this generalization do exist. For 
example, Larry Mcafee, a 34-year-old civil engineer, 
sustained a permanent high-cervical-cord injury in 
a motor vehicle accident in 1985. The accident left 
him ventilator dependent. State benefits for a home 
attendant were denied, but Mcafee was reluctant to 
be placed in a nursing home. He successfully 
petitioned the courts in Georgia for the right to be 
disconnected from the ventilator. Consequently, state 
funds were allocated to establish a group residence 
for ventilator-dependent patients in Augusta, 
Georgia. Mcafee currently resides in that residence 
with state support. 

Group Community Facilities 

In recent years, alternatives to placement of 
ventilator-dependent patients at home or in nursing 
homes have been considered — the concept of group 
accommodation in a noninstitutional setting. Such 
an approach for clinically appropriate patients offers 
a number of potential advantages: 

• shared attendants, 

• shared cost, 

• a community residential setting (vs an 
institution), 

• patient independence encouraged, and 

• vocational and occupational activity facilitated. 

The limited experience with this approach in the 
United States has not been related to any concern 



about the validity and favorability of the concept 
but rather to the lack of public-payer support, legal 
restrictions on persons attempting to care for 
chronically ill patients (health codes), and consequent 
liabilities for prospective private investors. 

The best example of the noninstitutional group 
facility is the product of the work of Mary Williams 
RN who directs such a private-sector effort (New 
Start Homes Inc, Chatworth CA). This pilot project 
in group residential living was initiated in 1982. 
Through tireless work by Ms Williams, a special 
waiver program was introduced by the California 
legislature in 1987. The Congregate Living Health 
Facilities Law was an amendment to the Health and 
Safety Code and allows for public funds to be 
allocated for qualifying patients requiring this care. 
At the end of 1990 this venture owned three houses 
in residential areas with a total of 14 ventilator- 
dependent patients. An additional small number of 
disabled nonventilator patients with neuromuscular 
disease are also resident in these homes. 

This private initiative serves as an outstanding 
example of a humane and efficient method of 
providing long-term care that allows the patient to 
maintain a place within a community without the 
institutionalization of a nursing home or the severe 
family disruption associated with home care. Current 
initiatives are aimed at obtaining appropriate 
Medicare certification that would allow for 
reimbursement from federal sources for group 
residential care. 



The International Experience 

Studies have not yet documented prolonged 
ventilatory care in intensive care units and the need 
for modulation of the care milieu. Less data are 
available about cost — perhaps because socialized 
systems as yet do not have the methodology or the 
incentive to monitor and 'fine tune' the cost of 
maintaining these more chronic critically ill patients. 

I have observed that home care in general is less 
accessible and less accepted by the medical 
community outside the United States. The full 
spectrum of home care (and respiratory care is no 
exception) as it has developed in the United States 
is not available outside this country. Availability is 
limited and acceptance by physicians seems to be 



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PLACEMENT FOR VENTILATOR-DEPENDENT PATIENTS 



constrained by the lack of appropriate resources and 
service industries to meet patient needs. 

In most parts of the world, chronic ventilatory 
support is not a well-developed field of expertise. 
Physicians in other countries may be more likely 
to make unilateral decisions regarding chronic or 
prolonged life support than would physicians in the 
United States. Chronic ventilator care outside the 
U.S. has focused on postpoliomyelitis patients, high 
quadriplegics, and patients with neuromuscular 
disease. However, two programs for chronic 
ventilator care in England and France are excellent 
models. '8.19 

In France, a national system for care of patients 
with chronic respiratory insufficiency is in place. 
A central organization, the National Home Care 
Association for Chronic Respiratory Insufficiency 
(ANTADIR), is the national organization respon- 
sible for a decentralized publicly funded program 
to provide home oxygen and ventilator care. In 1 986, 
approximately 1,200 patients were reported to be 
on full-time or part-time ventilatory support in that 
system. A breakdown of patient diagnoses and the 
number of patients on positive- and negative- 
pressure ventilation is not available. 

In Great Britain, a program has been reported that 
involves intermediate care for patients requiring 
ultimate discharge from hospital. A limited 
framework for group residential living also exists, 
and facilities for respite care have been developed. 
The program is geographically limited but open to 
patients from anywhere in the country. The program 
was developed originally to service the needs of the 
Intensive Care Unit at St Thomas Hospital in London. 
This combined effort involving private and public 
funding is limited in its scope by its size and location 
but has provided service to several hundred patients 
since its inception. 

REFERENCES 

1. Munoz E, Josephson J, Tenenbaum N, et al. Diagnosis 
related groups: Costs and outcome for patients in the 
intensive care unit. Heart and Lung 1989;18:627-633. 

2. Mohr CH, Hill NS. Long term follow up of nocturnal 
ventilatory assistance in patients with respiratory failure 



due to Duchennes type muscular dystrophy. Chest 
1990;97(l):91-96. 

3. Bach JR, Alba AS. Management of chronic alveolar 
hypoventilation by nasal ventilation. Chest I990;97:52- 
57. 

4. Splaingard ML, Prates RC, Jefferson LS, Rosen CL. Home 
negative pressure ventilation: Report of 20 years of 
experience in neuromu.scular disease. Arch Phys Med 
Rehabil 198.5;66:239-242. 

5. Cropp A, DiMarco AF. Effects of intermittent negative 
pressure ventilation on respiratory muscle function in 
patients with severe chronic obstructive pulmonary disease. 
Am Rev Respir Dis 1987;135:1056-1061. 

6. Garay SM, Turino GM, Goldring RM. Sustained reversal 
of chronic hypercapnia in patients with alveolar 
hypoventilation syndromes. Am J Med 1981;70:269-274. 

7. O'Donohue WJ, Giovanonni RM, Goldberg AL et al. Long- 
term mechanical ventilation: Guidelines for management 
in the home and at alternate community sites. Chest 
1986;90(July, Suppl):IS-37S. 

8. Make BJ, Gilmartin ME. Rehabilitation and home care 
for ventilator assisted individuals. Clin Chest Med 
1986;7:679-691. 

9. Petty TL, Farrington JF. The intensive respiratory care 
unit. Clin Notes Respir Dis I97I;I0(1):3-1 1. 

10. Bone RC, Balk RA. Noninvasive respiratory care unit: 
A cost effective solution for the future. Chest 1 988;93:390- 
394. 

11. Indihar FJ, Walker NE. Experience with a prolonged 
respiratory care unit — revisited. Chest 1984;86:616-620. 

12. Daly BJ, Rudy EB, Thompson KS, Happ MB. Devel- 
opment of a special care unit for chronically critically 
ill patients. Heart & Lung 1991;20:45-52. 

13. Plummer AL, O'Donohue WJ, Petty TL. Consensus 
conference on problems in home mechanical ventilation. 
Am Rev Respir Dis 1989;40:555-560. 

14. Nochomovitz ML. Respiratory home care. In: Chemiack 
NS, ed. Chronic obstructive pulmonary disease. Philadel- 
phia: WB Saunders Co, 1991:576-584. 

15. Goldberg AI. Life sustaining technology and the elderly: 
Prolonged mechanical ventilation factors influencing the 
treatment decision. Chest 1988;94:1277-1282. 

16. Nochomovitz ML, Peterson DK, Stellato TK. Electrical 
activation of the diaphragm. Problems Respir Care 
1990;3:507-533. 

17. Cooper H, Blumberg EC. Pioneering respiratory care in 
the nursing home. Am Health Care Assoc J 1984; 1 0:59- 
62. 

18. Goldberg AI, Faure EAM. Home care for life-supported 
persons in England — The Responaut program. Chest 
1984;86:910-914, 

19. Goldberg AI, Faure EAM. Home care for life-supported 
persons in France: The regional association. Rehabil Lit 
1986;47:60-64. 



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RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



Long-Term Mechanical Ventilation: 
Patient Selection and Discharge Planning 

Mary E Gilmartin RN BSN RRT 



Introduction 

Over the past decade, an increasing number of 
patients have been maintained in the home on Ufe- 
support equipment. This population of patients has 
consisted of (1) those unable to be weaned from 
ventilatory support after an acute episode of 
respiratory failure and (2) those who are being 
electively ventilated with intermittent noninvasive 
modes of ventilatory support.''"' 

Successful outcome for ventilator-assisted patients 
depends on many factors: appropriate selection of 
patients for care outside the hospital, stability of the 
patient, patient and family motivation, and their ability 
to leam. Comprehensive discharge planning and 
coordination of hospital and community services are 
major components of care, and play a key role in 
the success of home care. 

Patient Selection Based on 
the Underlying Disease Process 

If the goals of home mechanical ventilation are 
to extend life, enhance quality of life, provide an 
environment to enhance individual potential, reduce 
morbidity, improve physical and physiologic function. 



Ms Gilmartin is Adult Clinical Specialist, National Jewish 
Center for Immunology and Respiratory Medicine, Denver, 
Colorado. 

A version of this paper was presented by Ms Gilmartin during 
the Long-Term Mechanical Ventilation Symposium at the 1990 
Annual Meeting of the American Association for Respiratory 
Care in New Orleans. Louisiana. 

Reprints: Mary E Gilmartin RN BSN RRT, Adult Clinical Nurse 
Specialist, National Jewish Center for Immunology and 
Respiratory Medicine, 1400 Jackson St, Denver CO 80206. 



and be cost-effective,' proper selection of patients is 
extremely important. (Not every patient who is unable 
to be weaned from mechanical support is candidate 
for home care, and for some the home ventilation 
option should not even be considered or offered.) 

Appropriate Candidates for Home Ventilation 

Most of the reported experiences with home 
ventilator care have shown that patients with 
neuromuscular or skeletal disorders are the best 
candidates for long-term ventilatory support.2i3-is-24 
Table 1 lists the medical conditions that may necessitate 
long-term mechanical ventilation, classified according 
to neuromuscular, chest-wall and diaphragmatic 
disorders, and primary pulmonary disease. 

Why are patients with neuromuscular or skeletal 
disorders the best candidates? Many patients with 
these disorders can be maintained on noninvasive 
ventilatory support. They do not have problems with 
airflow obstruction, and their ventilation and oxygen 
requirements do not change very much over time. 
Some patients (such as those with kyphoscoliosis, 
poliomyelitis, thoracoplasty, and Ondine's curse) 
may only need ventilation at night, thus decreasing 
the need for backup ventilators and allowing them 
much more mobility. Because some of the 
neuromuscular disorders are slowly progressive, a 
decision about long-term ventilation can be made 
on an elective rather than emergency basis, which 
lessens complications and shortens the hospital stay. 
Lastly, many patients with neuromuscular or skeletal 
disorders seem to adjust better to the increasing 
disability associated with their disease than those 
with chronic lung disease. Many patients with 
neuromuscular or skeletal disease have had to deal 
with their disability throughout their lives but 



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PATIENT SELECTION & DISCHARGE PLANNING 



patients with lung disease are affected later in life 
and therefore may feel particularly limited by their 
dyspnea (physically and psychologically). 

Although, in general, those with neuromuscular 
disorders are the best candidates for long-term 
ventilation in the home, exceptions do exist. If a 
child with a neuromuscular disorder develops 
chronic lung or airway involvement because of 
multiple infections related to mechanical ventilation 
and tracheostomy, he may not be medically stable; 
or if he has had inadequate ventilation and periods 
of hypoxemia, he may develop cor pulmonale and 
pulmonary hypertension.' The medical caretakers 
need to be aware of these problems and be sure 
that the child is stable before discharge to home. 

Inappropriate Candidates for Home Ventilation 

Of the many patients with neuromuscular disease, 
those with amyotrophic lateral sclerosis (ALS), in 
general, do not adjust well to their progressive 
disability. These patients tend to have a much more 
rapid progression, with loss of swallowing and 
speech and total dependency on their caretakers. 
The loss of independence related to this disease 
causes depression and feelings of hopelessness, 
which makes it very difficult to provide successful 
home care. 

Other disorders that stimulate much controversy 
related to the use of long-term support fall into the 
category of primary pulmonary disease (Table 1 ). 
Adults with severe pulmonary disease who need 
ventilatory support usually have concomitant 
pulmonary hypertension and cor pulmonale; may 
also have rapid deterioration secondary to changes 
in airflow obstruction, infections, and heart failure; 
and are more difficult to manage at home because 
of the potential for frequent changes in ventilation 
and oxygen requirements. Children and adults with 
cystic fibrosis are not considered good candidates; 
placing them on a ventilator does not diminish the 
problems with copious secretions and recurrent 
infections, and the ventilator and artificial airway 
may actually increase the chance of infection. 

Patients who have pulmonary fibrosis generally 
are not considered good candidates for ventilatory 
support, even in an acute situation, because of their 
need for very high ventilatory pressures and oxygen. 
Their hypoxemia and dyspnea may be refractory 



to medical management, and the mechanical 
ventilator may actually increase their work of 
breathing. ' 

Infants with bronchopulmonary dysplasia may not 
be clinically stable until they are 1-2 years of age 
because of the immaturity of the lungs and airways. 
This instability may necessitate that they remain 



Table 1. Conditions that may Necessitate Long-Term 
Mechanical Ventilation 



Neuromuscular Disorders 

Central Nervous System 

Central hypoventilation syndromes 
Ondine's Curse 
Amold-Chiari malformation 

Spinal Cord 

Traumatic injuries 
Thoracic myelomeningocele 
Syringomyelia 

Anterior Horn Cell (Lower Motor Neuron) 
Poliomyelitis 

Spinal muscle atrophy (Werdnig-Hoffman) 
Amyotrophic lateral sclerosis* 

Muscle 

Muscular Dystrophy (Duchenne's, limb girdle, myotonic 

dystrophy) 
Congenital myopathies 

Peripheral Nerve 
Phrenic neuropathies 
Diaphragmatic paralysis 

Idiopathic 

Postsurgical 
Guillain-Barre syndrome 

Chest- Wall and Diaphragmatic Defects 

Kyphoscoliosis 
Postsurgical (thoracoplasty) 
Diaphragmatic hernia 

Primary Pulmonary Disorders 

Tracheomalacia 

Bronchiectasis 

Bronchopulmonary dysplasia 

Chronic aspiration 

Chronic bronchitis, emphysema* 

Cystic fibrosis* 

Interstitial lung disease (multiple causes)* 

Adult respiratory distress syndrome 



*Less appropriate disorders for home mechanical ventilation 



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PATIENT SELECTION & DISCHARGE PLANNING 



in the hospital until sufficient maturation occurs to 
assure a safe transition to the home without adverse 
consequences. 

Clinical and Physiologic Stability 
Co-Existing Disease 

Many patients, especially the elderly population, 
may have other medical diseases that will interfere 
with successful discharge and home care. A cardiac 
evaluation may be appropriate, especially in the 
elderly, to rule out underlying cardiac dysfunction. 
When these patients are immobilized in the bed 
or chair, cardiac dysfunction may not be apparent; 
but, when a program of rehabilitation is started, 
the underlying disease interferes with their physical 
progress. 

Patients with terminal cancer who are on 
ventilatory support are not appropriate candidates 
for home care because of the time and expense 
needed to prepare the patient and family for the 
transition to home. Even with full-time professional 
caretakers in the home, the family may need to 
be responsible for some of the care. The equipment 
and supplies needed by these patients will also be 
very expensive and probably not justified from a 
cost-containment point of view. 

Other patients who may not be candidates for 
home care are those with unstable psychiatric illness. 
Their potential inability to make rational decisions 
or judgments about their care puts them at high 
risk for major physical and mechanical problems. 
They would need to have a family willing to take 
total responsibility for their care. 

Medical Readiness for Discharge 

If home care is to be successful and cost-effective, 
the patient must meet certain criteria of clinical and 
physiologic stability (Table 2). The patient should 
be stable for at least 2 to 4 weeks prior to discharge. 
You cannot write a home care plan for a moving 
target (personal communication, A Goldberg, 
presentation at annual ACCP meeting, Toronto, 
Canada, 1990). We may all have anecdotal reports 
of patients who have not met these criteria and 
survived at home, but, in general, this places a 
tremendous burden on the patient, family, and 
caregivers. 

The critically ill patient (one who needs frequent 
changes in ventilator settings, high oxygen concen- 



trations, and positive end-expiratory pressure [PEEP]) 
is still in need of intense medical care and is not ready 
for discharge. '•'*-2'' The ventilators used in the home, 
even though sophisticated, would require modifications 
to provide higher oxygen concentrations, PEEP, and 
adequate flow for synchronized intermittent mandatory 
ventilation (SIMV), '•**•''' which would greatly increase 
the potential for malfunction and error. 

The patient who requires frequent laboratory work 
because of unstable metabolic and acid-base status, 
which in turn necessitate changes in medications, 
is not ready to be discharged. The same applies 
to the patient who is having multiple episodes of 
infection and requires frequent coverage with 
antibiotics. 

In infants and children, nutritional status is very 
important not only for growth and development but 
for increasing their weaning potential.'^ Failure to 
thrive in an infant may be indicative of irreversible 
damage, and caring for this infant in the home may 
not be an option. Nutritional status needs frequent 

Table 2. Patient Stability and Medical Readiness for Discharge 

Control or absence of sustained dyspnea 

Acceptable arterial blood gases, with Fioj < 0.40 

Stable ventilator settings 

Flo, < 0.40 

Assist/control or pressure-limited mode (pediatrics) 

Limited use of PEEP 

Minimal fluctuations in airway resistance and compliance 

Stable 'free time" periods 

Optimal metabolic and acid-base status 

Absence of acute infectious processes 

Absence of life-threatening cardiac dysfunction or arrhythmias 

Other organ systems stable 

Ability to clear secretions and protect airway 

Adequate nutrition 

Progression of growth and development (in children) 

If artificial airway, a tracheostomy, not an oral or nasal airway 

Able to handle the daily stressors 

Management at home exjjected to be stable, without the need 
for readmission within at least 1 month 



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PATIENT SELECTION & DISCHARGE PLANNING 



monitoring to be sure that the patient is either 
maintaining or gaining weight and that the method 
of providing nutrition is appropriate for the patient. 
If the patient is being ventilated through an 
artificial airway, it must be a tracheostomy, not an 
oral or nasotracheal tube. The patient must also be 
able to clear secretions either through suctioning 
or adequate coughing. Lastly, the patient and family 
must be able to deal with the stress involved in 
home ventilator care. 

Nonmedical Aspects of Patient Selection 

The medical diagnosis and stability of the patient 
are only part of the process related to successful 
home care. Each patient with whom we deal in 



the hospital comes to us with his own individual 
strengths and weaknesses; it is these aspects and 
other individual characteristics that play a major 
role in successful outcomes. 

Internal Factors — Coping Skills 

The patient may have the 'best' diagnosis, but 
have no coping skills or other resources that would 
allow for successful home care. Because these 
nonmedical aspects of patient selection may play 
a significant role in home care, it is important to 
assess factors that would make a patient an 'ideal' 
candidate. This profile of an ideal candidate can 
serve as a basis for choosing the acceptable 
candidate (Table 3).^^ A determination of the 



Table 3. Patient Characteristics That May Determine Success in Home Ventilator Care 



Ideal 



Individual Coping Style 

Optimistic 

Motivated 

Resourceful 

Flexible 

Adaptable 

Sense of humor 

Directive 

Support Systems 

Close family & 
social supports 

Education 

College degree 
Ability to learn 

Financial Resources 

Adequate personal 
assets 
Optimal health 



Acceptable 



Optimistic 
Motivated 
Sense of humor 



Social supports 



Ability to learn 
Mechanically astute 

Adequate health 



Unacceptable 



None 



Lack of family & 
social supports 

Altered mental status 
Unable to learn 



Lack of personal assets 
Lack of health insurance 



Medical Condition 

Stable neuromuscular 

disease 
Adequate free time 

off ventilator 
No other illnesses 



Stable neuromuscular 
or obstructive disease 

Limited or no time off 
ventilator 



Medically unstable 



Self-Care Ability 

Able to provide self- 
care and/or direct 
others 



Able to provide self-care 



Unable to care for 
self or direct 
others 



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PATIENT SELECTION & DISCHARGE PLANNING 



patient's individual coping style can be elicited 
through a psychological evaluation and the patient's 
past performance during times of stress.^'^^ If the 
patient and family don't feel optimistic about their 
future and lack the motivation needed to get through 
the hospitalization and discharge-planning process, 
then home care may not be successful. The patient 
must take an active part in planning his care and 
in the decision-making process; without this 
participation, the risk of failure is greatly 
increased.25 The resourceful, flexible, and adaptable 
person will have an easier time dealing with the 
many potential problems related to changes in 
physical condition, caregiver support, and equip- 
ment function. A sense of humor is one asset that 
I have found to be important in successful home 
care; being able to relieve stresses through humor 
is extremely helpful to patients, families, caregivers, 
and multidisciplinary team members. 

External Factors 

Support systems. Close family and social supports 
are integral components of the ideal patient profile. 
Many patients who cannot provide their own care 
will need to direct others in the provision of daily 
care. Maintaining the family identity, with the 
patient assuming much of his prior role in the family 
structure and continuing with certain responsibil- 
ities, contributes a great deal to successful home 
care. When the patient is treated as the 'sick' person, 
his identity and role in the family will change ,which 
will contribute to loss of self-esteem and self-worth. 

Education. The college-educated patient, unless 
factors such as cognitive impairment, depression 
or anxiety interfere with learning, will be able to 
understand and assimilate all of the concepts of 
medical and physical care as well as the functioning 
of the equipment. 25-26 For many patients and 
families, an educational background is not important 
as long as they can learn about their care and utilize 
the knowledge to function safely in the home 
environment. 

Financial considerations. The patient's financial 
situation should not be a contributing factor in 
successful home care; but in this era of cost- 
containment and reimbursement issues, the patient 
who has his own personal assets and an excellent 
insurance policy will have fewer worries. The issues 



of equipment, supplies, home modifications, and 
caretaker support will not be major obstacles to 
discharge planning and home care for those with 
adequate finances. 
The Ideal vs the Acceptable Candidate 

The person with stable neuromuscular disease, 
no other medical problems, and the ability to be 
off the ventilator for significant periods of time is 
an ideal candidate for home ventilator care. When 
a patient can breath spontaneously for long periods 
of time, equipment needs are less and there are 
fewer problems associated with equipment malfunc- 
tion and power interruptions. Also, the patient who 
can perform his own care or direct others in 
providing his care is ideal. 

Regretfully, few people fit this profile of the ideal 
candidate, but by using it we can decide on the 
criteria that make a patient 'acceptable' for home 
care. These patients must still be motivated and 
optimistic, otherwise discharge planning and home 
care will be frustrating, unrewarding, and likely to 
fail. A sense of humor is a key asset with these 
patients, because they may have to deal with many 
frustrations related to obtaining supplies, insurance 
woes, and lack of understanding by other people. 
Home care ventilator patients may not adapt well 
to change and may be rigid in their thinking and 
daily routine, which will create anxiety when 
problems arise. Caregivers need to be aware of these 
personality traits and be somewhat flexible in their 
routines. 

These patients may live alone but have helpful 
friends and/or may live in a supportive community. 
Many small communities will rally to the support 
of one of their members by providing meals, 
transportation, social activities, or even some 
personal care. Patients will need to be able to ask 
for help, to accept the support offered to them, and 
to learn how to take care of themselves and 
understand the functions of the equipment, even 
though they may not have any formal education. 
Patients who have some mechanical aptitude will 
feel less threatened about the equipment.--'' 

Adequate third party coverage is necessary, even 
if it is a state Medicaid program. If these patients 
do not have any personal funding, they or their 
families will need to provide the necessary care, 
supplemented only by intermittent nursing care 
covered by the health insurance policy. 



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PATIENT SELECTION & DISCHARGE PLANNING 



The Unacceptable Candidate 

Patients 'unacceptable' for home care are those 
patients who do not have any of the personal, 
educational, or financial assets important for its 
success. These patients are either unlikely to be 
able to deal with the daily stressors or their cognitive 
functioning is limited or altered, which makes home 
an unsafe environment for them. They have no 
family or community support and somehow 'fall 
through the cracks' for adequate health insurance 
or state-funded medical coverage. Because of 
unstable disease and lack of other assets, successful 
home care is unlikely and if placed in the home, 
morbidity and mortality may be greatly increased. 

If we look not only at the medical condition of 
the patients but at their own individuality, the 
decision for placement in the home can be made 
somewhat more easily. These patient assets must 
be looked at early in the hospital course prior to 
making any decisions about home care and, if 
possible, before elective ventilatory support is 
initiated. 

Comprehensive Discharge Planning 
Multidisciplinary Team 

Discharge planning requires the support and 
interest of the physician, nurses, and other allied 
health professionals. If the driving force is only 
to get the patient out of the hospital as quickly 
as possible, the preparation for discharge and home 
care will not be smooth and the patient and family 
will get mixed messages. The team must work 
together to make the transition from hospital to home 
a safe and satisfactory one (Fig. 1). 

The physician is the leader of the team because 
he makes the judgment calls about the stability of 
the patient and the feasibility for home care. Because 
he has this responsibility, it is extremely important 
that he has an interest and some expertise in 
rehabilitation and home care. Further, he needs to 
understand the intricacies involved in the discharge- 
planning process and realize that it is not 
accomplished overnight. 

Many centers that routinely discharge ventilator 
patients will have a discharge-planning coordinator 
who will oversee the day-to-day process of preparing 
the patient for home. This person will work directly 
with the physician, be the link between the hospital 



and home services, and work directly with the 
patient and family. 

Patient and family are also key members of the 
team. Without their motivation, desire, and 
participation in the rehabilitation and discharge- 
planning process, home care will not be successful. 
Careful attention must be paid to their progress and 
willingness to participate throughout the discharge 
preparation and ultimately when home 

The amount of involvement of other members 
of the team (except for nursing, respiratory therapy, 
and the durable medical equipment [DME] 
company) depends on the patient's condition and 
self-care needs. Because the hospital program 
should be individualized for each patient, each of 
the services may have some involvement with the 
patient even on a limited basis. The home care 
services need to be involved early in the discharge- 
planning process in order for a smooth transition 
to take place. The therapist who will be involved 
with the patient after discharge should meet with 
the patient and family, and may also participate 
in teaching the patient and family, which will make 
the patient feel comfortable with the therapist and 
ease the transition to home. 

Communication among all members of the team 
is mandatory for successful discharge planning. The 



Physician 



Discharge Plannin); 
Coordinator 



Nursing 

Respiratory Therapy 
Rehabilitation Services 
Speech Therapy 
Social Services 
Psychiatry/Psychology 
Clinical Nutrition 



Durable Medical 
Equipment Company 

Community Nursing 
Agencies 

Community Services 

School Services 



Patient, Family 



Fig. 1. Physician authorized services coordinated by the 
discharge planner. 



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RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



PATIENT SELECTION & DISCHARGE PLANNING 



multidisciplinary team should meet on a regular 
basis to discuss progress, set new goals for the 
ultimate discharge to home, and discuss any 
problems that have developed. 

Patient and Family Education 

Education is a major component of the discharge- 
planning process and needs to begin early in the 
patient's hospital stay. Initially, this education may 
consist of explaining the procedures and the reasons 
for doing them. The patient and family will also 
learn by observation, and this makes it critical that 
good technique be used when performing proce- 
dures.26 It's not uncommon for an observant patient 
or family member to comment that what they are 
being taught is different from what they see 
performed by others. 

A basic checklist of skills that the patient and 
family will need to know should be developed; skills 
that will be needed for individual situations can 
be added to the list. Table 4 lists some of the skills 
the patient and family must learn prior to discharge; 
they not only need to learn these skills, but they 
must become proficient at them. Documentation is 
necessary to determine when the task was taught 
and when it was performed independently by the 
patient and family. 

The team needs to decide who will be doing the 
teaching and how it will progress; the patient should 
not be inundated with all of the material at one 
time. The patient should learn in a timely manner 
and progress from simple to more complex tasks. 
As each new task is learned, it should be reinforced 
by all team members and the patient given positive 
feedback about progress. The patient and family 
need to understand the importance of practice; many 
times they think that if the procedure is done 
correctly once, they do not need to do it again. 

Particular attention needs to be paid to emergency 
measures (such as those to be used when the 
ventilator fails, the airway obstructs, or bleeding 
occurs), and these measures should be taught in 
a stepwise fashion. The patient and family need 
to be prepared for all emergencies (Table 4), even 
though they may never happen; for that reason, some 
of the potential emergency situations should be 
simulated. Both patient and family caregivers will 
function better in a stressful situation if there is 
a step-by-step plan of action to follow. 



In one recent study, patients and families felt 
that learning skills through demonstration at the 
bedside with only a few people present was the 
most beneficial.9 They also felt that the sessions 
should be short and that learning skills was more 
beneficial than learning about their lung disease. 
Teaching methods should be geared to the patient's 
learning capabilities. Some patients will need to 
have the procedures written on large cue cards to 
refer to as they practice a procedure. Many times 

Table 4. Skills Needed by Patient and/or Caregivers prior to 
Discharge 

Self-Care Techniques 

Airway Management 

Tracheostomy and stoma care 

Cuff care 

Tracheal suctioning 

Changing the tracheostomy tube 

Changing the tracheostomy ties 
Chest physical therapy techniques 

Percussion 

Vibration 

Coughing 
Medication administration 

Oral 

Inhaled 
Bed-to-chair transfers 
Feeding-tube care 
Indwelling-catheter care 
Implantable-I.V.-line care 
Bowel care 
Switching from the ventilator to weaning device 

Equipment Maintenance 

Ventilator 
Humidifier 
Suction machines 
Battery and charger 
Oxygen administration 
Manual resuscitator 
Troubleshooting for problems 
Cleaning and disinfection 

Emergency Measures 

Ventilator failure 

Power failure 

Dislodged tracheostomy tube 

Obstructed airway 

Cuff leaks 

Shortness of breath 

Ventilator circuit problems 

Infection 

Falls 

Bleeding 

Cardiac arrest 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



211 



PATIENT SELECTION & DISCHARGE PLANNING 



the psychosocial evaluation will help decide which 
teaching method will be appropriate for the patient 
(eg, some patients may not be able to read but are 
embarrassed to admit it). Special needs should be 
determined early so that time is not lost in educating 
the patient or his family. 

Selection of Caregivers 

Some patients will provide all of their own care 
and only need minimal support from family members. 
In other situations, the family will be the primary 
caregiver. Many times, it will depend on the patient's 
condition and what the insurance company will cover — 
skilled vs unskilled care, specific activities requiring 
care, hours per day of coverage needed. If the patient 
only needs unskilled care for personal hygiene, 
dressing, and meal preparation, a home health aide 
can be used. In many states, there are centers for 
independent living that assist patients to continue to 
live in a home environment by helping them find 
accessible housing and providing funding for personal 
care attendants. Because these personal care attendants 
are hired and trained by the patient or family, there 
are no restrictions on the complex care that diey 
perform. These programs have allowed many patients 
with neuromuscular disease to live at home, at a much 
lower cost than using professional caretakers — even 
though they are ventilator-dependent. However, it is 
important to note that these patients need to possess 
the patient characteristics discussed under patient 
selection (Table 3). 

Rehabilitation 

An individualized program must be developed 
for each patient, depending on the patient's primary 
problem. For patients with COPD, many of the 
principles of pulmonary rehabilitation can be 
utilized in their care plan. For patients with a 
neuromuscular disorder, the goal may be to prevent 
further loss of function and to maintain joint 
mobility. The use of assistive devices for mobility 
and physical functioning will increase patient 
independence and improve quality of life. 

In any rehabilitation program, realistic short- and 
long-term goals are necessary. All members of the 
team need to work together to prevent fragmentation 
in care, to assist the patient in meeting goals, and 
to help the patient progress from the simple to the 
more complex tasks. For many patients, the ability 
to move from the bedside by having the ventilator 
mounted on a wheelchair or cart gives them a sense 



of freedom. Patients who require a wheelchair for 
long-term use will need a prescription and 
professional guidance in the selection process. ^'^ 
Having specific wheelchair accessories and adaptive 
equipment to meet the patient's needs is critical, 
as is anticipating and planning for needs that may 
arise as the patient's physical condition changes. 

A rehabilitation program for children may be very 
extensive and require many more services than for 
adults. Children need frequent evaluation of their 
physical, emotional, and intellectual development. 
If they are progressing well, as they grow, their 
equipment will need modification or replacement. 

Home Care Equipment 

Once the feasibility of home care is established, 
a durable medical equipment (DME) company 
should be contacted. The DME selected should be 
one that can provide all of the necessary equipment 
and supplies, has experienced home care respiratory 
therapists, and has previous experience with home 
ventilator care. An equipment and supply list should 
be developed and individualized for each patient. 
(If the patient has an artificial airway, some 
equipment is mandatory, as listed in Table 5.) 

Table 5. Accessory Equipment for Patients with Artificial 
Airways in the Home 



Essential 

Manual resuscitator bag 

Humidifier 

Suction machine 

electric 

battery 
Backup ventilator* 
Battery* 
Battery charger* 
Ventilator cable to battery* 
Secondary ventilator alarms 



According to Need 

Oxygen 

Hygroscopic condenser 

humidifier 
Water traps 
Compressors 

medication delivery 

bland aerosol 
Generator 
Remote alarms 



*Needed for any patient who cannot maintain spontaneous 
ventilation for 4 consecutive hours or who lives in a rural 



It is important that the patient use the ventilator 
that will be used in the home for at least two weeks 
prior to discharge. He will also need to get 
accustomed to using other equipment such as the 
suction machine, air compressors, or oxygen 
because these are operationally different from the 



212 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



PATIENT SELECTION & DISCHARGE PLANNING 



piped-in compressed gases and vacuum available 
in the hospital. Everything that will be available 
in the home should be used in the hospital, and 
the hospital room should be set up as the patient's 
room will be in the home. 

Assessment of the Home Environment 

An assessment of the patient's home should be 
made by a hospital team member and the DME 
early enough in advance of discharge to allow time 
for modifications. Other team members may need 
to visit the home, depending on the patient's 
functional status and mobility. Table 6 lists the more 

Table 6. Assessment of the Ventilator-Dependent Patient's 
Home 



Accessibility 

In and out of home 
Bathroom 
Kitchen 
Between rooms 
Wheelchair mobility 

Doorway width 

Thresholds 

Stairways 

Carpeting 

Equipment 

Space 

Electrical power supply 

Amperage 

Grounded outlets 

Environment 

Temperature 
Lighting 
Living space 



common aspects of the home environment that need 
to be observed. 

Patients who will be using quite a bit of electrical 
equipment may need additional wiring and 
placement of grounded outlets. I like to use an 
electrical power strip with a circuit breaker for the 
patient's ventilator and accessory equipment 
because it can be mounted on a table or cart with 
the ventilator and be clearly visible. 

Ideally, space should be adequate to allow for 
the patient's comfort and privacy and equipment 
and supply placement and storage, but realistically 
this may not always be possible. Home modifica- 
tions are out-of-pocket costs and not always 
affordable by the patient. It is also important not 



to have the home look like a hospital. This can 
be avoided by taking care to keep as many personal 
items in the room as possible (desk, pictures, book 
case, favorite furniture). 

Nursing Agencies and Community Resources 

The choice of a nursing agency may depend on 
the patient's need for continuous or intermittent care, 
the need for other allied health professionals, and 
each agency's experience with home ventilator care. 
Other factors to be considered in the selection 
process are whether they ( 1 ) are certified Medicare 
providers, (2) accept assignment for state-funded 
Medicaid patients, and (3) as with any home care 
agency, are accredited by the Joint Commission of 
Accreditation for Healthcare Organizations 
(JCAHO). The nursing agency should be contacted 
well in advance of discharge to give the staff ample 
time to meet with the patient and family, participate 
in discharge-planning conferences, and obtain the 
necessary information on reimbursement. 

Other community resources (such as housekeep- 
ing, meal preparation, transportation, and school 
services) should be contacted depending on the 
needs of the patient. 

Transition from Hospital to Home 

Whenever possible, trials away from the hospital 
should be part of the discharge-planning process. 
However, this should only be initiated when the 
patient and family have learned all of the skills 
necessary for successful home care. Generally, 
overnight trials in the home are done just prior to 
discharge. These trials will help the patient and 
family gain confidence in their own abilities, help 
both the patient and management team address 
unanticipated problems, and ensure continued 
teaching of aspects of care in which the patient 
and family are weak. 

Medical Follow-Up 

Prior to discharge, the physician who will be 
providing medical care should be identified. This 
may be a physician caring for the patient in the 
hospital or it may be the patient's local medical 
doctor. The physician will need to be updated 
frequently about the patient's condition, understand 
the home care plan, and have a backup consultant 
for ventilatory problems (if he's not a pulmonolo- 
gist). All facets of care should be considered — eg, 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



213 



PATIENT SELECTION & DISCHARGE PLANNING 



if this physician will be involved with tracheostomy 
tube changes, has he had prior experience? All 
follow-up care must be organized in advance of 
discharge to decrease the stress for the patient and 
family. 

Specific Issues Related to 
Long-Term Ventilator Patients 

Airway Management 

Each patient with a tracheostomy should have 
his airway assessed via bronchoscopy for tube 
placement, airway obstruction by granulation tissue, 
tracheomalacia, and tracheal stenosis. The tracheal 
tube should be positioned comfortably in the stoma 
with the flange resting against the neck without any 
pressure, and the curve of the tube should be 
appropriate for the patient's anatomy. The inner 
diameter should be appropriate to the patient's 
anatomy for comfort and to decrease airway 
resistance. The length of the tube may need to be 
customized depending on tracheal problems.^^ 

If the patient will be progressing to a fenestrated 
tracheostomy tube, the position of the fenestration 
within the airway should be assessed. If the 
fenestration is not positioned fully in the airway, 
irritation of tracheal tissue can result during repeated 
placement of the inner cannula with resultant 
bleeding, granulation tissue formation, or intrusion 
of tissue into the fenestration. An intrusion of tissue 
can result in the inability to place the inner cannula, 
so proper positioning is important. 

The vocal cords and upper airway should also 
be assessed for edema, granulation tissue, and vocal 
cord movement — especially if the patient can be 
off the ventilator for long periods of time and will 
have the ability to phonate normally. Vocal-cord 
dysfunction will interfere with swallowing and will 
need early intervention to prevent aspiration into 
the lungs. 

Evaluation and Treatment of 
Swallowing Dysfunction 

Reports are scarce on the incidence of dysphagia 
in patients requiring ventilatory support through an 
artificial airway.^^ The mechanisms of swallowing 
disorders may be related to the rigidity of the 
tracheostomy tube and anchoring of the trachea to 
the strap muscles, decreased laryngeal sensation 
related to the diversion of air through the stoma, 
and overinflation of the tracheal tube cuff.^^ 



All patients with an artificial airway should be 
evaluated for swallowing disorders; this can be done 
at the bedside by the speech pathologist, using foods 
and liquids of varying consistencies with food 
coloring added to the food. The patient is suctioned 
and positioned upright, small amounts of liquids 
and solids are given to him, and then he is suctioned 
with the cuff inflated and then deflated. Aspiration 
into the airway may not always be immediately 
noted because of pooling in the valleculae and 
pyriform sinuses, which may cause spillover into 
the airway at a later time. 

If there is any suspicion of aspiration, this bedside 
evaluation should be followed by a radiographic 
evaluation. A video fluoroscopy with barium is the 
best method to determine swallowing disorders, but 
this technology may not be available in all medical 
centers. With this technique, the patient is given 
small boluses of barium in different consistencies 
while the video fluoroscopy is being done. The video 
is extremely helpful because the swallow may be 
so fast that small amounts of aspiration may not 
be noted on the fluoroscopy alone. The radiologist 
and speech pathologist can review the video and 
assess each aspect of the swallowing mechanism. 

Once diagnosed, the treatment for swallowing 
disorders will depend on the cause. For some 
patients, positioning upright with the head tilted 
forward may be all that is necessary. For others, 
teaching compensatory mechanisms and tongue 
exercises may help. Some patients may require foods 
of only one consistency to prevent aspiration, and 
others will not be able to have oral feedings at all; 
these patients will need a nasal or gastric feeding 
tube placed for nutrition. Patients who cannot 
tolerate oral or nasogastric feedings will need 
intravenous hyperalimentation. 

Communication Strategies 

When a patient cannot communicate normally 
because of an artificial airway and/or problems with 
phonation secondary to bulbar weakness, an 
alternative means of communication should be 
available. As with swallowing disorders, the speech 
therapist is invaluable in the assessment and 
treatment of communication problems. Table 7 
shows many of the communication alternatives 
available for the ventilator-assisted patient. 

If the patient is able to speak with his normal 
voice either by cuff deflation or an uncuffed 



214 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



PATIENT SELECTION & DISCHARGE PLANNING 



Table 7. Communication Alternatives for Ventilator-Assisted 
Patients 

Cuff deflation (or uncuffed tracheostomy tube) 

'Talking' tracheostomy tube 

Electrolarynx 
neck placement 
intra-oral placement 

Pneumatic voice device 

Lip speaking 

Writing 

Sign language 

Communication boards 

Alphabet keyboards with printed messages 

Preprogrammed computers with voice synthesizers 

tracheostomy tube and augmented tidal volumes on 
the ventilator, his sense of self-esteem and feelings 
of self-control will be greatly increased. For other 
patients, a 'talking' tracheostomy tube will allow 
normal speech. Many simple devices such as the 
electrolarynx or sophisticated, highly technical 
devices such as computers with voice synthesizers 
are available to augment speech. The choice of a 
device needs to be individualized, although some 
patients may refuse to use the electronic devices 
because they are self-conscious about the projected 
sound of their voice. The patient's, family's, and 
caretaker's frustration is greatly increased when the 
patient cannot be understood, so it is important that 
this aspect be considered. 

'Free' Time from the Ventilator (Weaning) 

Prior to the patient's discharge, the amount of 
free time he can tolerate off the ventilator should 
be determined. If weaning is possible, the technique 
should be simple and able to be carried out in the 
home. Weaning with a critical care ventilator on 
CPAP and/or a pressure support mode cannot be 
continued in the home, and the amount of free time 
with these methods may differ greatly when weaning 
with a T-piece. Portable ventilators are not adequate 
for SIMV without modification as discussed earlier. 

The amount of free time should be consistent 
from day to day, and the patient should be stable 
within predetermined limits. As the patient 



progresses to longer weaning periods, ability to 
perform functional activities while weaning needs 
to be assessed. If the patient can wean for long 
periods of time and be active, he will have much 
more freedom and mobility. 

Psychosocial Issues 

For any patient who has been hospitalized for 
a long period of time, the transition to home may 
provoke much anxiety. For patients who are on life- 
support equipment, the impending discharge to 
home may stir up many feelings. As much as the 
patient wants to be at home, the change from a 
protected environment and experienced caretakers 
to the home with only family or self as caretaker 
will increase anxiety and ambivalence about going 
home.^25 Patients and families react to this in many 
ways; they may become increasingly dependent and 
angry, and have many somatic complaints. The 
family may miss teaching appointments or not visit 
as often, or they may fail to make necessary home 
arrangements. Frequent family meetings, realistic 
discussions about home care, and meetings between 
the patient, his family, and other ventilator-assisted 
patients and their families will help. 

After discharge, the patient and family will need 
to establish routines and gain confidence in 
themselves. They will need frequent reassurance and 
review of the skills that they have learned. If they 
are providing all of the care, they may feel 
overburdened and overwhelmed by the care 
requirements, especially until they establish 
routines. Respite care can help with some of these 
issues, but a mechanism needs to be in place to 
provide it (neighbors or relatives who are trained 
to relieve the primary caregiver for short periods 
of time). 

Conclusion 

The process of discharging a ventilator-assisted 
patient has many intricate facets and requires the 
coordination of many services and people. Tran- 
sition to home ventilator care is easier when the 
criteria for patient selection is realistic; trying to 
prepare an unstable patient or one without support 
systems for home is an exercise in futility. The 
frustration resulting from this futility only leads to 
anger and a feeling of impotence among the team. 
When this happens, many of the team members 
will not be interested in or have the energy to deal 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



215 



PATIENT SELECTION & DISCHARGE PLANNING 



with another patient deemed to be a candidate for 
home care. We need to ensure safe, quality care 
that is cost-effective, and at the same time we need 
to feel a sense of accomplishment for a job well 
done. 

REFERENCES 

1. O'Donohue WJ, Giovannoni RM, Goldberg AI, et al. 
Long-term mechanical ventilation: Guidelines for 
management in the home and alternate community site. 
Chest 1986;90(Suppl):lS-37S. 

2. Make BJ, Gilmartin M. Rehabilitation of ventilator- 
assisted individuals. Clin Chest Med 1986;7:679-691. 

3. Kettrick RG, Donar ME. Ventilator-assisted infants and 
children. Problems Respir Care 1988;l(2):269-278. 

4. Leger P, Jennequin J, Gerard M, Robert D. Home positive 
pressure ventilation via nasal mask for patients with 
neuromuscular weakness or restrictive lung or chest-wall 
disease. Respir Care 1989;34(2):73-77. 

5. Prentice WS. Transition from hospital to home. Problems 
Respir Care 1988;1(2):174-191. 

6. Goldberg AL Mechanical ventilation and respiratory care 
in the home in the 1990s: Some personal observations. 
Respir Care 1990;35(3):247-259. 

7. LaFond L, Homer J. Psychological issues related to long- 
term ventilatory support. Problems Respir Care 
l988;l(2):241-256. 

8. O'Donohue WJ Jr. Patient selection and discharge criteria 
for home ventilator care. Problems Respir Care 
1988; 1(2): 167- 174. 

9. Thompson CL Richmond M. Teaching home care for 
ventilator-dependent patients: The patients' perception. 
Heart Lung 1990;19:79-83. 

10. Wilhelm L, Plummer A. Role of the home care 
practitioner. Problems Respir Care 1988;l(2):279-292. 

1 1 . O'Donnell C, Gilmartin ME. Home mechanical ventilators 
and accessory equipment. Problems Respir Care 
1988;l(2):217-240. 

12. Plummer AL, O'Donohue WJ, Petty TL, et al. Consensus 
conference on problems in home mechanical ventilation. 
Am Rev Respir Dis 1989;140:555-560. 

13. Sivak ED, Crodasco EM, Gipson WT, et al. Home care 
ventilation: The Cleveland Clinic experience from 1977 
to 1985. Respir Care 1986;31:294-302. 

14. Schreiner MS, Downes JJ, Kettrick RG, et al. Chronic 
respiratory failure in infants. JAMA 1987;258:3398-3404. 



15. Kacmarek R, Stanek KS, McMahon KM, Wilson RS. 
Imposed work of breathing during synchronized 
intermittent mandatory ventilation provided by five home 
care ventilators. Respir Care 1990;35(5):405-414. 

16. Donar ME. Community care: Pediatric home mechanical 
ventilation. Holistic Nurse Pract 1988;2(2):68-80. 

17. LaFond L, Make BJ, Gilmartin ME. Home care costs 
for ventilator-assisted individuals (abstract). Am Rev 
Respir Dis 1988; 137(4, Part 2):62. 

18. Fischer DA, Prentice WS. Feasibility of home care for 
certain respiratory-dependent restrictive or obstructive 
lung disease patients. Chest 1982;82:739-743. 

19. Indihar FJ, Walker NE. Experience with a prolonged 
respiratory care unit revisited. Chest 1984;86:616-620. 

20. Make BJ. Long-term management of ventilator-assisted 
individuals: The Boston University experience. Respir 
Care 1986;31:303-310. 

21. Splaingard ML, Frates RC, Harrison GM, et al. Home 
positive pressure ventilation: Twenty years experience. 
Chest 1983;84:376-382. 

22. Splaingard ML, Frates RC, Jefferson LS, et al. Home 
negative pressure ventilation: Report of 20 years of 
experience in patients with neuromuscular di.sease. Arch 
Phys Med Rehab 1985;66(4):239-242. 

23. Czorniak M, Make BJ, Gilmartin ME. Home mechanical 
ventilation: Clinical course of patients with neuromuscular 
disease (NMD) and chronic obstructive pulmonary disease 
(COPD) (abstract). Am Rev Respir Dis 1987; 135(4, Part 
2):A194. 

24. Robert D, Gerard M, Leger P, et al. La ventilation 
mecanique a domicile definitive par tracheotomie: De 
I'insuffisant respiratoire chronique. Rev Fr Mai Resp 
1983;11:923-936. 

25. Gilmartin ME. Long term mechanical ventilation outside 
the hospital. In: Pierson DJ, Spearman CB, Kacmarek 
RM, eds. Foundations of respiratory care. New York: 
Churchill Livingstone Inc, (in press). 

26. Gilmartin ME. Patient and family education. Clin Chest 
Med l986;7(4):6l9-627. 

27. Ringel SP. Neuromuscular disorders: A guide for patient 
and family. New York: Raven Press, 1987. 

28. Wilson DJ. Airway management of the ventilator-assisted 
individual. Problems Respir Care 1988; 1(2): 192-203. 

29. Weisinger W, Goldsmith T. Artificial ventilation: Its 
impact on communication and swallowing problems. 
Problems Respir Care 1988;1(2):204-2I6. 



216 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 




Now,,, 

Seven Reasons 
Every Asthmatic 
Should Use ASSESS 

I Provides accurate peak flow measurement' 

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3 Warns of bronchospasm prior to onset of 
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lL Signals need to adjust dosage or seek medical attention" 
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flftS References 1. Hendler J. Shapiro S. Ogirala R. AldrichT: Accuracy of new and used portable 
= = == peak flow meters. Abstract presented at the 46th Annual Meeting of the American College of Altei^ 
and Immunology, Orlando, FL. November 11-15, 1989. 2. Shim CS, Williams MH: Relationship of 
wheezing to the severity of obstruction in asthma. Arch Intern Med M3:S90. 1983. 3. Williams 
MH: Expiratory flow rates: Their role in asthma therapy. Hospital Praciice:95, October, 1982. 
4. Woolcock AJ. Yan K. Salome CM: Effect of therapy on bronchial hyperresponsiveness in the 
long-term management of asthma. Clinical Allergy 18:165, 1988. 



Products Inc. 



Drug 
Capsule 



Hugh S Mathewson MD, Section Editor 



Theophylline — A Continuing Enigma 



Hugh S Mathewson MD 



Since strong coffee was recom- 
mended for the treatment of asthma 
over a century ago,' the methyl- 
xanthines (caffeine, theobromine, 
theophyUine) have been used for both 
prophylaxis and therapy of broncho- 
spasm. Caffeine is still used as a 
respiratory stimulant for neonatal 
apnea, whereas theobromine has 
practically disappeared. However, an 
estimated 10 million Americans take 
theophylline, according to industry 
officials, about half of them for asthma, 
the rest for chronic lung disease.^ Even 
this is a modest figure compared to 
the number of people who took the 
drug 25 years ago. 

Theophylline once had clinical 
stature as a cardiac stimulant, a 
peripheral vasodilator, and a diuretic. 
It was often prescribed for congestive 
heart failure and for angina pectoris. 
In these therapeutic applications, it has 
been superseded by more effective 
drugs. Now its status as a broncho- 
dilator is subject to challenge, partic- 
ularly when it is administered intra- 
venously for treatment of acute 
asthmatic episodes. Although moni- 
toring of plasma concentrations has 
become routine,' some clinicians have 
expressed doubt whether theophylline 
can be given with predictable safety, 
and whether its contribution to the 
treatment of asthma is sufficient to 
justify its continued use. 



Dr Mathewson is Professor of Anesthesi- 
ology and Medical Director, Respiratory 
Therapy, University of Kansas Medical 
Center, Kansas City, Kansas. 



A recent paper by Lam and 
Newhouse'' summarizes in detail the 
shortcomings of theophylline. In an 
accompanying editorial, Newhouse^ 
states that it has been a first line 
antiasthmatic drug for 50 years despite 
its relatively weak bronchodilator 
effect, narrow therapeutic window, 
numerous drug interactions, and low 
therapeutic index. Its recent surge of 
popularity, which peaked about 1988, 
is attributable to the introduction of 
sustained-release preparations, which 
bridged the nocturnal gap of 6 hours 
that could not be covered by beta- 
adrenergic aerosols.' However, new 
long-acting beta-adrenoceptor agonists 
such as salmeterol and formoterol* 
appear to provide continuous bron- 
chodilator efficacy for periods of 10 
to 12 hours. Also, aerosol administra- 
tion has been markedly improved by 
the use of metered dose inhalers 
supplemented by mist-confining 
devices (so-called spacers). This is of 
especial benefit to children and elderly 
adults, for whom the use of conven- 
tional nebulizers may be grossly 
inefficient. 

A more flexible and adaptable 
regimen for control of asthma may be 
provided by inhaled beta-adrenergic 
agents, perhaps supplemented by the 
anticholinergic aerosol ipratropium 
bromide thus avoiding the use of oral 
bronchodilator preparations entirely.' 
One reason that heavy maintenance 
dosage of theophylline persists is probably 
that beta-adrenoceptor agonists are not 
given in adequate doses."* The two-puff 
self-administration recommended in 
some package inserts does not deliver 
enough drug to accomplish an optimal 
response. 



The potential for dose-related toxic 
side actions of theophylline is well 
documented."''" The therapeutic 
plasma level range is about 10 to 20 
/ng/mL. Toxic side actions in the form 
of emesis, precordial pain, tachyar- 
rhythmias, and central-nervous-system 
hyperirritability are likely to appear at 
concentrations above 20 /ug/mL. 
Convulsions and death have occurred 
at concentrations of 25 ^ig/mL, 
although seizures are relatively rare at 
values below 40 ixg/mU*. Sustained- 
release preparations create the problem 
of continued absorption in the face of 
toxic manifestations. Although acti- 
vated charcoal administered orally will 
accelerate clearance of theophylline, 
levels above 100 //g/mL will require 
invasive measures, including hemoper- 
fusion through charcoal cartridges.'" 

Most cases of severe toxicity occur 
in patients receiving repeated oral or 
parenteral theophylline." Long-term 
intoxication appears to render patients 
more prone to seizures than do short- 
term overdoses," which compounds 
the difficulty in establishing a relation- 
ship between plasma concentration 
and severity of side actions." Rapid 
intravenous administration of amino- 
phylline in 500-mg doses can result in 
sudden death from cardiac 
arrhythmia.'* The drug should be 
injected slowly over a period of 20 to 
40 minutes, and should not be given 
to a patient already taking theophylline 
until a plasma concentration value has 
been obtained. 

Dose scheduling in children is 
particularly difficult, and an adequate 
therapeutic response may not be 
obtained unless plasma values are close 
to toxic levels." It has been contended 



218 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



DRUG CAPSULE 



that behavioral abnormalities and poor 
school performance can be attributed 
to oral theophylline use,^"'^' although 
this remains unproven.^^ 

The use of theophylline as a neonatal 
respiratory stimulant has recently been 
questioned. Its central action in 
preterm infants is partly attributable to 
the fact that up to 25% of the drug 
is converted in vivo to caffeine. 
However, theophylline inhibits 
erythropoietin production; it has been 
employed to prevent erythrocytosis in 
patients after renal transplantation.^' 
There is current concern that the drug 
may have a similar depressant effect 
on erythropoietin synthesis in the 
neonate, and therefore could be 
responsible for causing some cases of 
anemia of prematurity.^^ 

The Association of Trial Lawyers 
of America (ATLA) held a news 
conference October 30, 1990, warning 
of the hazards of theophylline.^ They 
reported 26 cases in which Association 
members provided legal representation 
for alleged injuries and preventable 
deaths involving theophylline use. The 
ATLA has urged the Food and Drug 
Administration (FDA) to ban over- 
the-counter theophylline preparations, 
and to require that package inserts be 
revised to warn of potential hazards. 
The FDA did not comment, but there 
were spirited replies from the Amer- 
ican College of Allergy and Immuno- 
logy and from the Schering-Plough 
Corporation, which has nearly 50% of 
the prescription theophylline market in 
the U.S. Dale B Sparks MD, president 
of the College, was quoted as saying: 
"We've used theophylline for 50 years, 
and physicians are well aware of the 
complications." A spokesman for 
Schering-Plough stated that about 60 
million prescriptions have been written 
for the company's theophylline 
products since 1985. The incidence of 
serious adverse effects reported to the 
FDA during that period was 1.3/ 
100,000 prescriptions.^ 

The status of theophylline would 
probably be improved if more were 



known about its mechanism of action. 
Whether the drug produces broncho- 
dilatation primarily by relaxing smooth 
muscle or by inhibiting the action of 
spasmogens is unclear. There is current 
focus on the adenosine-receptor- 
blocking property of methylxan- 
thines," but the role of adenosine in 
the pathogenesis of asthma is still 
undefined. Theophylline can improve 
exercise capacity in some COPD 
patients by mechanisms that are 
probably unrelated to bronchodilata- 
tion."**"'" The therapeutic response of 
the patient with asthma, itself a disease 
with multifactorial etiology, can at this 
time be assessed only empirically. In 
a recent editorial," Niewoehner 
pointed out that theophylline is a drug 
ill-suited for widespread administra- 
tion. In a retrospective review at his 
institution (a Veterans Administration 
Medical Center), the risk of a fatal or 
life-threatening complication of theo- 
phylline therapy was about 0.5% per 
year, in a population largely composed 
of elderly patients with COPD and 
other medical problems. Extrapolation 
of this figure to the total U.S. popu- 
lation receiving theophylline suggests 
that several thousand patients expe- 
rience severe adverse reactions each 
year. Theophylline continues to have 
staunch advocates, however. The latest 
edition of Goodman and Gilman's 
Pharmacological Basis of Therapeutics 
( 1 990), arguably the most authoritative 
source book in the U.S., offers the 
following statement: 

The oral administration of 
theophylline-containing prepara- 
tions has been used to produce 
bronchodilatation for over 50 years. 
The efficacy of theophylline is 
unquestioned, and, with supple- 
mental inhalation of beta2- 
adrenergic agonists, successful treat- 
ment of most patients with moder- 
ately severe chronic asthma has been 
a reality for nearly 20 years. 

This is followed by admonitions 
concerning its narrow margin of safety, 
the augmented susceptibility to seizures 



brought on by long-term administra- 
tion, and the necessity to titrate the 
drug in successive stages until maximal 
efficacy is reached. Each upward 
adjustment of dosage is to be preceded 
by a determination of plasma concen- 
tration. Also, it is noted that, over the 
long term, theophylline appears to have 
little effect on bronchial hyper- 
responsiveness. 

The primary emphasis in the treat- 
ment of asthma and COPD has now 
shifted toward control of the chronic 
inflammatory process responsible for 
bronchial hyperreactivity, with less 
importance attached to providing 
symptomatic relief of bronchospasm." 
Potent topical steroids" and cromolyn 
congeners'"* can provide good long- 
term control, with occasional supple- 
mentation by beta-adrenoceptor 
agonists or anticholinergic agents. 
Large doses of steroids are advocated 
for acute treatment of asthma 



attacks. 



It has been stated that 



theophylline preparations contribute 
but little when added to combined 
beta-agonist and steroid therapy."'^" 

In the maintenance of asthma 
control. Lam and Newhouse" place 
dose-optimized inhaled steroids as first- 
line therapy. Inhaled adrenoceptor 
agonists are second-line medications, 
anticholinergic aerosols third-line, and 
theophylline, if needed at all, can 
provide a minor steroid-sparing func- 
tion in severe asthmatics. 

The question whether theophylline 
should be relegated to obsolescence can 
probably not be answered unless placebo- 
controlled trials are carried out.'* This 
kind of study would be expensive, 
cumbersome, and time-consuming, and 
is not likely to be undertaken because 
some COPD patients respond pooriy to 
steroids and others cannot tolerate beta- 
adrenoceptor agonists. It is likely that the 
use of theophylline for asthma will decline 
in the foreseeable future, but its place 
in the treatment of selected patients will 
remain secure until longer acting and 
more potent agents whose effects are safer 
and more predictable are introduced. 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



219 



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DRUG CAPSULE 



REFERENCES 

1. Salter H. On some points in the 
treatment and clinical history of 
asthma. Edinburgh Med J 
1859;4:1109-1115. 

2. American Medical News. American 
Medical Association, November 16, 
1990. 

3. Rowe DJF, Watson ID, Williams J, 
Berry DJ. The clinical use and 
measurement of theophylline. Ann 
Clin Biochem 1988;25:4-23. 

4. Lam A, Newhouse MT. Management 
of asthma and chronic airflow limita- 
tion: Are methylxanthines obsolete? 
(editorial). Chest 1990;98:44-52. 

5. Newhouse MT. Is theophylline obso- 
lete? Chest 1990;98:1-3. 

6. Helm SG, Meltzer SM, Improved 
control of asthma in the office setting: 
A large-scale study of once-daily 
evening doses of theophylline. Am J 
Med 1988;85(Suppl lB):30-34. 

7. Ullman A, Svedmyr N. Salmeterol, 
a long acting inhaled B2 adrenoceptor 
agonist: Comparison with salbutamol 
in adult asthmatic patients. Thorax 
1988;43:674-678. 

8. Lofdahl C-G, Svedmyr N. Inhaled 
formoterol, a new betai-adrenoceptor 
agonist, compared to salbutamol in 
asthmatic patients (abstract). Am Rev 
Respir Dis 1988; 137(4, Part 2):330. 

9. Newhouse MT, Dolovich MB, Con- 
trol of asthma by aerosols. N Engl 
J Med 1986;315:870-874. 

10. Jenne JW. Theophylline is no more 
obsolete than "two puffs qid" of 
current betai agonists (editorial). 
Chest 1990;98:3-4. 

11. Littenberg B. Aminophylline treat- 
ment in severe acute asthma— A 
meta-analysis. JAMA 1988;259: 
1678-1684. 

12. Siegel D, Sheppard D, Gelb A, 
Weinberg PP. Aminophylline in- 
creases the toxicity but not the efficacy 
of an inhaled beta-adrenergic agonist 
in the treatment of acute exacerbations 
of asthma. Am Rev Respir Dis 1985; 
132:283-286. 

13. Mountain RD, Neff TA. Oral theo- 
phyUine intoxication: A serious error 
of patient and physician under- 
standing. Arch Intern Med 1984; 
144:724-727. 



14. Goldberg MJ, Park GD, Berlinger 
WG. Treatment of theophylline 
intoxication. J Allergy Clin Immunol 
1986;78:811-817. 

15. Bertino JS Jr, Walker JW. Reassess- 
ment of theophylline toxicity: Serum 
concentrations, clinical course, and 
treatment. Arch Intern Med 1987; 
147:757-760. 

16. Paloucek FP, Rodvold KA. Evalua- 
tion of theophylline overdoses and 
toxicities. Ann Emerg Med 1988; 
17:135-144. 

17. Aitken ML, Martin ER. Life- 
threatening theophylline toxicity is not 
predicted by serum levels. Chest 
1987;91:10-14. 

1 8. Rail TW. Drugs used in the treatment 
of asthma. In: Oilman AG, Rail TW, 
Nies AS, Taylor P, eds. Goodman and 
Oilman's The pharmacological basis 
of therapeutics. New York: Pergamon 
Press, 1990:618-637. 

19. Weinberger M. Pharmacologic 
management of asthma. J Adolesc 
Health Care 1987;8:74-83. 

20. Rachelefsky GS, Wo J, Adelson J, 
et al. Behaviour abnormalities and 
poor school performance due to oral 
theophylline use. Pediatrics 1986; 
78:1133-1138. 

21. Furakawa CT, DuHamel TR, 
Weimer L, Shapiro GG, Pierson WE, 
Bierman CW. Cognitive and behav- 
ioral findings in children taking 
theophylline. J Allergy Clin Imnunol 
1988;81:83-88. 

22. Creer TL, McLoughlin JA. The effects 
of theophylline on cognitive and 
behavioral performance. J Allergy 
Clin Immunol 1989;83:1027-1029. 

23. Roberts RJ. Drug therapy in infants: 
Pharmacologic principles and clinical 
experience. Philadelphia: WB 
Saunders Co, 1984. 

24. Aranda JV, Chemtob S, Laudignon 
N, Sasyniuk BI. Pharmacologic effects 
of theophylline in the newborn. J 
Allergy Chn Immunol 1986;78:773- 
780. 

25. Bakris GL, Sauter ER, Hussey JL, 
Fisher JW, Guber AO, Winsett R. 
Effects of theophylHne on erythro- 
poietin production in normal subjects 
and in patients with erythrocytosis 
after renal transplantation. N Engl J 
Med 1990;323:86-90. 

26. Beach RS, Donlon D, Escoto D, 
McCarthy J, Napolitano A, Sosa R. 



Theophylline for erythrocytosis after 
renal transplantation (letter). N Engl 
JMedl990;323:1635. 

27. Williams M. Adenosine antagonists. 
Med Res Rev 1989;9:219-243. 

28. Guyatt GN, Townsend M, Pugsley 
SO, et al. Bronchodilators in chronic 
air-flow limitation: Effects on airway 
function, exercise capacity and quality 
of life. Am Rev Respir Dis 1987; 
135:1069-1074. 

29. Aubier M, Roussos C. Effect of 
theophylline on respiratory muscle 
function. Chest 1985;88(2, Suppl): 
91S-97S. 

30. Mahler DA, Matthay RA, Snyder PE, 
Wells CK, Loke J. Sustained release 
theophylline reduces dyspnea in non- 
reversible obstructive airway disease. 
Am Rev Respir Dis 1985;131:22-25. 

31. Niewoehner DE. Theophylline 
therapy: A continuing dilemma 
(editorial). Chest 1990;98:5. 

32. Barnes PJ. A new approach to the 
treatment of asthma. N Engl J Med 
1989;321:1517-1527. 

33. Kraan J, Koeter GH, Van der Mark 
TW, et al. Dosage and time effects 
of inhaled budenoside on bronchial 
hyperreactivity. Am Rev Respir Dis 
1988;137:44-48. 

34. Gonzalez JP, Brogden RN. Nedo- 
cromil sodium: A preliminary review 
of its pharmacodynamic and pharma- 
cokinetic properties, and therapeutic 
efficacy in the treatment of reversible 
obstructive airways disease. Drugs 
1987;34:560-577. 

35. Fanta CH, Rossing TH, McFadden 
ER Jr. Glucocorticoids in acute 
asthma: A critical controlled trial. Am 
J Med 1983;73:845-851. 

36. Ratto D, Alfano C, Sipsey J, Glorsky 
MM, Sharma O. Are intravenous 
corticosteroids required in status 
asthmaticus? JAMA 1988;260:527- 
529. 

37. Barclay J, Whiting B, Addis GJ. The 
influence of theophylline on maximal 
response to salbutamol in severe 
chronic obstructive pulmonary 
disease. Eur J Clin Pharmacol 1982; 
22:388-393. 

38. Guyatt GH, Sackett D, Taylor DW, 
Chong J, Roberts R, Pugsley SO. 
Determining optimal therapy: 
Randomized trials in individual 
patients. N Engl J Med 1986;3 14:889- 
892. 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



221 



Test Your 
Radiologic Skill 



Charles G Durbin Jr MD and 

Douglas B Eden BS RRT, Section Editors 



A Possible Complication of Central Venous Catheterization 

Curt M Morey CPFT RRT, David C Lain PhD RRT, Bjorn Thorarinsson MD, 
Arthur A Taft MHS RRT, and Shelley C Mishoe MEd RRT 



A 5 1 -year-old woman presented to our emergency 
room complaining of nausea, vomiting, fever, night 
sweats, and a productive cough (1 cup of green 
sputum/day for the previous 4 days). She denied 
pleuritic chest pain, shortness of breath, abdominal 
pain, diarrhea, headaches, and neck stiffness. 

Physical examination revealed her temperature 
to be 4rC [314°K], heart rate 132/min, blood 
pressure 125/45, and respiratory rate 22/min. Chest 
auscultation revealed diminished breath sounds in 
the middle posterior portion of the left lung and 
inspiratory crackles, which were more pronounced 
in the left lung than in the right. A chest radiograph 
was taken (Fig. 1). 

The white-blood-cell count was 14,700/|jt,L with 
a left shift. The hemoglobin was 12.2 g/dL with 
a hematocrit of 35.1%. SMA-10 was normal. 
Analysis of arterial blood, with the patient breathing 
room air, revealed pH 7.51, PaOj 60 torr [8.0 kPa], 
Paco2 30 torr [4.0 kPa], calculated HCO3 24.2 mEq/ 
L [24.2 mmol/L], and measured SaOj 90.9%. 

A sputum gram stain revealed gram-positive 
cocci, gram-negative rods and cocci, and a few white 
blood cells. She was admitted to our hospital with 
a diagnosis of community-acquired pneumococcal 
pneumonia and was started on intravenous (I.V.) 
cefuroxime. During the first 48 hours after 



Mr Morey was a student in the Respiratory Therapy Program, 
Dr Lain was Clinical Instructor and Coordinator of Research 
and Education, Dr Thorarinsson is Assistant Professor of 
Medicine and Director of the Medical Intensive Care Unit, 
Mr Taft is Assistant Professor of Respiratory Therapy and 
Director of Clinical Education, and Ms Mishoe is Associate 
Professor of Respiratory Therapy and Chairman of the 
Respiratory Therapy Program — Medical College of Georgia, 
Augusta, Georgia. Mr Morey is now a staff therapist at Phoebe 
Putney Memorial Hospital, Albany, Georgia. Dr Lain is now 
Product Specialist, Ohmeda, Baltimore, Maryland. 




Fig. 1. Admission chest radiograph of a 51 -year-old 
woman complaining of nausea, vomiting, fever, night 
sweats, and productive cough. 



admission, the patient continued to be febrile, and 
exhibited increasing respiratory distress. Chest 
radiographs revealed diffuse bilateral infiltrates. 
Administration of erythromycin was initiated, and 
the patient was moved to the intensive care unit. 

The patient continued to deteriorate, and on the 
third hospital day required intubation and mechan- 
ical ventilation. Later that morning, a bronchoscopy 
was performed and bronchoalveolar lavage fluid was 
sent for microbiologic evaluation including direct 
fluorescent antibody for legionella. Later that day, 
a pulmonary artery catheter was placed that revealed 
a normal pulmonary capillary wedge pressure. 



222 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



TEST YOUR RADIOLOGIC SKILL 



On Day 6 and Day 11 of hospitalization, central 
venous lines were placed. (On Day 10, an 
unsuccessful attempt to place a central venous line 
resulted in a right pneumothorax, which was 
successfully treated with tube thoracostomy.) On 
Day 20, the patient was extubated, following an 
uneventful course of weaning from the ventilator. 
On Day 21, she was moved to the general ward. 
A few days later, a chest radiograph was taken (Fig. 
2). 




Fig. 2. Chest radiograph of a 51 -year-old woman with 
resolving pneumococcal pneumonia, taken after extuba- 
tion and subsequent to 17 days of mechanical ventilation. 



r 



Questions 

Radiographic Findings on Admission: What does 
the chest radiograph in Figure 1 show? What 
anatomic areas (lobes, segments) are affected? 
Radiographic Findings after Extubation: What 
does the chest radiograph in Figure 2 suggest? 
Further Testing: What test(s) might help confirm 
or deny your diagnosis? 

Answers and Discussion 
on Next Page 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



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Answers 

Radiographic Findings on Admission: The chest 
radiograph in Figure 1 reveals alveolar infiltrates 
in the superior segment of the left lower lobe. The 
clear diaphragmatic border makes basilar involve- 
ment unlikely. The clear left-heart border rules out 
lingular involvement; therefore, the superior 
segment of the left lower lobe is the most likely 
anatomic location. This was further supported by 
a retrocardiac shadow, and was confirmed by a 
lateral chest radiograph. 

Radiographic Findings after Extubation: Figure 
2 suggests resolving left-lower-lobe infiltrates and 
an elevated right hemidiaphragm, possibly due to 
unilateral diaphragmatic paralysis. 
Further Testing: A sniff test was performed under 
fluoroscopy that revealed paradoxical motion of the 
right hemidiaphragm, thus confirming the diagnosis 
of right hemidiaphragm paralysis. 

Discussion 



Central venous catheterization is indicated when 
I.V. access is needed for high volume intravenous 
fluid administration and/or peripheral LV. access 
is difficult to obtain. '^ The two phrenic nerves, one 
for each hemidiaphragm, arise from the third, fourth, 
and fifth cervical nerves. As the phrenic nerves 
descend from their point of origin, they curve around 
the lateral borders and obliquely cross the anterior 
surfaces of the anterior scalene muscles. They pass 
posterior and lateral to the internal jugular veins 
and underneath the sternocleidomastoid muscles as 
they enter the thorax. At this point, they pass 
posterior to the subclavian veins and anterior to 
the subclavian arteries descending into the anterior 
mediastinum, parallel to the lateral surfaces of the 
brachiocephalic veins.^ •'' 

Important complications and potentially lethal 
hazards associated with insertion of central venous 
lines and pulmonary artery catheters have been 
reported: pneumothorax, '•^•'♦.ft-io bleeding and/or 
hemothorax, '•2'*'^-'*-"'-' 2 infection, '•^Ae-'^'O'^ venous 
air embolism,^-''''-**" carotid or subclavian artery 
puncture,"-'* cardiac dysrhythmias,^"'''''^ perfora- 
tion of the pulmonary artery, '0'3.i4,i6 hemopty- 
sis,'2.'6 intrapulmonary hemorrhage,^- '2. '5 pulmo- 
nary infarction,'"'''' pulmonic valve injury, '3-''' 
tricuspid valve injury, '3-"* catheter embolus,''-'"-''' 



thoracic duct laceration on the left side,^ pleural 
effusion,^ pulmonary embolus,'' brachial plexus 
damage,^ ventricular tachycardia,^ vascular occlu- 
sion, '^ intracardiac knotting of the pulmonary artery 
catheter,''* thrombosis,'"* complete heart block in a 
patient who already had left-bundle-branch 
blockage,^'' and injury to the phrenic nerve.^-^-''-^-^' 
We suspect that in the case we report, central 
venous-line placement resulted in injury to the 
phrenic nerve and consequent unilateral diaphrag- 
matic paralysis. 

Unilateral diaphragmatic paralysis can be 
suspected if one of the hemidiaphragms is observed 
to be elevated in the chest radiograph.^ However, 
this is not observed often in the mechanically 
ventilated patient, and only becomes obvious when 
the patient is off the ventilator and breathing 
spontaneously as in the case of our patient. In 
addition to radiographic evidence, electromyogra- 
phic^'' and/or fluoroscopic'' evidence is needed to 
confirm diagnosis of unilateral diaphragmatic 
paralysis. Having the patient sniff (creating a brief 
but intense contraction of the diaphragm and other 
respiratory muscles) during fluoroscopy is referred 
to as the sniff test. If unilateral diaphragmatic 
paralysis is present, when the sniff test is performed 
the healthy hemidiaphragm will descend sharply 
(move caudad) and the paralyzed hemidiaphragm 
will rise (move cephalad).22-23 

The recovery of the injured diaphragm depends 
upon the extent of the injury. If a blunt injury or 
partial laceration of the phrenic nerve has occurred, 
recovery is usually within several months.^ If the 
nerve has been severed, end-to-end anastomosis and 
sural nerve grafts may be successful in treating the 
injured nerve. ^ If the nerve has been paralyzed with 
medication, such as lidocaine, recovery is usually 
prompt."* The case presented in this report is too 
recent to assess whether permanent damage to the 
phrenic nerve has occurred. 



REFERENCES 

1 . Smith BE, Modell JH, Gaub ML, Moya F. Complications 
of subclavian vein catheterization. Arch Surg 
1965;90:228-229. 

2. Vest JV, Pereira MB, Senior RM. Phrenic nerve injury 
associated with venipuncture of the internal jugular vein. 
Chest 1980;78:778-779. 



224 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



Wffi5gS:55aW: 




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.... ... 






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www 



EACH YEAR, IT IS ESTIMATED THAT 

5,000 CHILDREN DIE FROM 
RSV COMPLICATED INFECTIONS! 



Consider treatment with ribavirin aerosol. 



For infants hospitalized with lower respiratory tract disease 



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severe or complicated RSV 



yJ^^^^J This includes infants with ^^^Ql^SEHQ 



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Since severity of illness is often 



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determination of the blood gas(!S is often necessary. Infants 



[Pa02 levels of less tha n 65 mmHg 
I increasing PaC02 levels 



and those with 



should be considered as 



candidates for ribavirin therapy. Oximetry may be used 
as a non-invasive means of determining the arterial oxygen 
saturation. Infants who might be considered for treatment 
are those hospitalized with lower respiratory tract disease 



which is not initially severe, but 



who may be at some 



I increased risk of progr essing 
I by virtue of young age 



to a more complicated course 



(< 6 weeks), or in wh(mi prolonged 



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li^Mrazole* 




avirin) 

•psol administratiM 

covery. 



Kathy Foltz, R.N. 
Marseilles, Illinois 61341 

November 19, 1990 

ICN Pharmaceuticals, Inc. 

ICN Plaza 

3300 Hyland Ave. 

Costa Mesa, CA 92626 

Dear Sirs: 

I am not in the habit of writing letters to drug companies but this time 
I felt a true need. I want to thank you for how your drug helped my 
daughter recover from RSV. 

I am an O.R. supervisor in a surgery department. When my daughter, 
Nikki, was 9 months old, she developed what we thought was a cold; 
wheezing, congestion and fever. One night her wheezing worsened and her 
breathing became extremely rapid. She got progressively worse and at 
4 a.m., I took her to the Emergency room. There, they told me I was 
doing all the right things and sent us home with antibiotics. At home, 
Nikki 's condition deteriorated — faster respirations and significant 
retraction. I tried steam, gave the antibiotics and felt absolutely 
helpless. Years of nursing experience had not taught me what was 
happening to my daughter. I called our family physician a few hours 
later and explained Nikki ' s symptoms. He met us at the Emergency room. 
Nikki was admitted that night with a diagnosis of pneumonia. Blood 
cultures were ordered, IV antibiotics given and a test was done for 
something called RSV. 

I had never heard of RSV, but when the test returned positive, our 
physician immediately ordered a "mist treatment". I have since come 
to know this mist treatment as Virazole. Nikki was so sick at the 
initiation of treatment, I was afraid she would give up trying to 
breathe. 

Prayers do get answered. By the next afternoon, her breathing normalized 
and her color improved — she started smiling and playing again. Nikki 
remained on Virazole for three days and then we went home. 

In a small town, 100 miles south of Chicago, my physician knew about 
Virazole and was able to treat my daughter close to home. Had he not 
known, Nikki would have been shipped to a PICU in a large Chicago 
hospital. The physician, the staff and the drug saved my daughter. 

Thank you. 



K<^ ^(tVk^^'^- 



Kathy Foltz, R.N. 



Letter composed Irom actual experience and printed with permission o( Kathy Foltz. 



Virazole 

(ribavirin) 

lyophilized for aerosol admimstration 

Rapid response. Rapid recovery. 



PRESCRIBING INFORMATION 



WARNING: RIBAVIRIN AEROSOL SHOULD 
NOT BE USED FOR INFANTS REQUIRING 
ASSISTED VENTILATION BECAUSE PRECIPI- 
TATION OFTHE DRUG IN THE RESPIRATORY 
EQUIPMENT MAY INTERFERE WITH SAFE 
AND EFFECTIVE VENTILATION OF THE 
PATIENT Conditions lor safe use with a ventilator 
are still in development 

Deterioration ol respiratory lunction has been 
associated with ribavirin use in infants, and in adults 
with chronic obstructive lung disease or asthma 
Respiratory (unction should be carefully monitored 
during treatment II initiation ol ribavirin aerosol 
treatment appears to produce sudden deterioration 
ol respiratory lunction, treatment should be stopped 
and reinstituted only with extreme caution and 
continuous monitoring. 

Alttiough ribavirin is not indicated in adults, the 
physician should be aware that it is teratogenic in 
animals (see CONTRAINDICATIONS). 



DESCRIPTION: 

Virazole® (ribavirin) Aerosol, an antiviral drug, is a ste- 
rile, lyophilized powder to be reconstituted for aerosol 
administration Each 100 ml glass vial contains 6 grams 
ol ribavirin, and when reconstituted lo the recommended 
volume ol 300 ml with sterile water lor injection or sterile 
water tor inhalation (no preservatives added), will contain 
20 mg/ml ribavirin, pH approximately 5.5. Aerosolization 
IS to be carried out in a SPAG-2 nebulizer only 

Ribavirin is 1-beta-Dribofuranosyl-1,2,4triazole-3car- 
boxamide, with the lollowing structural formula: 






Ribavirin, a synthetic nucleoside, is 
a stable white crystalline compound 
( ^ with a maximum solubility in water ol 
142 mg/ml at 25°C and with only a 
slight solubility in ethanol. The empi- 
rical lormula is CsHijNjOs and the 
molecular weight is 244,2 Daltons. 



CLINICAL PHARMACOLOGY: 
Antiviral effects: 

Ribavirin has antiviral inhibitory activity in vitro against 
respiratory syncytial virus,' rfluenza vinjs. and herpes sim- 
plex virus. Ribavirin is also active against respiratory syn- 
cytial virus (RSV) in experimentally infected cotton rats,^ 

In cell cultures, the inhibitory activity of ribavirin tor RSV 
IS selective. The mechanism ol action is unltncwn. Re«rsal 
ol the in vilfo antiviral activity by guanosine or xanthosine 
suggests ribavirin may act as an analogue ol these cellular 
metabolites 
Immunologic effects: 

Neutralizing antibody responses to RSV were decreased 
m ribavirin treated compared to placebo treated mlants.^ 
The clinical significanceolthisobservation IS unknown. In 
rats, ribavirin resulted in lymphoid alropfry ol thymus, 
spleen, and lymph nodes Humoral immunity was reduced 
in guinea pigs and ferrets Cellular immunity was also 
mildly depressed m animal studies 
Microbiology: 

Several clinical isolates of RSV were evaluated tor 
ribavirin susceptibility by plaque reduction in tissue culture. 
Plaques were reduced 85-98% by 16 /xg/ml; however, 
plaque reduction varies with the test system The clinical 
significance of these data is unknown 
PtiarmKOklnetlct: 

Assay for ribavirin m human materials is by a radio- 
immunoassay which detects ribavirin and at least one 
metabolite 

Ribavirin administrered by aerosol is absorbed 
systemically Four pediatric patients inhaling ribavirin 
aerosol administered by face mask for 2.5 hours each day 
for 3 days had plasma concentrations ranging Irom 0,44 
to 1.55 >iM, with a mean concentration of 0.76 ^M. The 
plasma half-life was reported to be 9.5 hours Three 
pediatric patients inhaling nbavinn aerosol administered 
by face mask or mist lent for 20 hours each day for 5 days 
had plasma concentrations ranging from 1 .5 to 14 3 ^M. 
with a mean concentration of 6.8 ^M 

It IS likely that the concentration of ribavirin in respiratory 
tract secretions is much higher than plasma concen 



trations m view of the route of administration 

The bioavailability of ribavirin aerosol is unknown and 
may depend on the mode of aerosol delivery. After aerosol 
treatment, peak plasma concentrations are less than the 
concentration that reduced RSV plaque formation in tissue 
culture by 85 to 98%. After aerosol treatment, respiratory 
trad secretions are likely to contain ribavirin in concen 
trations many told higher than those required to reduce 
plaque formation However, RSV is an intracellular virus 
and serum concentrations may better reflect intracellular 
concentrations m the respiratory tract than respiratory 
secretion concentrations. 

In man, rats, and rhesus monkeys, accumulation ol 
ribavirin and/or metabolites in the red blood cells has been 
noted, plateauing in red cells in man in about 4 days and 
gradually declining with an apparent half-life of 4(3 days 
The extent of accumulation of ribavirin lollcfwing inhalation 
therapy is not well defined. 

INDICATIONS AND USAGE: 

Ribavirin aerosol is indicated m the treatment ol tios- 
pitaiized infants and young children with severe lower res- 
piratory tract infections due lo respiratory syncytial virus 
(RSV). In two placebo-controlled trials in infants hospi- 
talized with RSV lower respiratory trad intedion, ribavirin 
aerosol treatment had a therapeutic etfed, as judged by 
the redudion by treatment day 3 ot seventy of clinical 
manifestations ol disease.^'' Virus titers in respiratory 
secrdions were also significantly reduced with ribavirin in 
one ot these studies " 

Only severe RSV lower respiratory tract infection is to be 
treated with ribavirin aerosol. The vast majority of infants 
and children with RSV infection have no lower respiratory 
trad disease or have disease that is mild, self-limited, and 
does not require hospitalization or antiviral treatment. Many 
children with mild lower respiratory trad involvement will 
require shorter hospitalization than would be required for 
a full course of ribavirin aerosol (3 to 7 days) and should 
not be treated with the drug. Thus the decision to treat with 
ribavirin aerosol should be based on the severity ol the RSV 
intedion 

The presence of an underlying condition such as pre- 
maturity or cardiopulmonary disease may increase the 
severity of the infection and its risk to the patient. High risk 
infants and young children with these underlying condi- 
tions may benefit from ribavirin treatment, although efficacy 
has been evaluated in only a small number of such 
patients. 

Ribavirin aerosol treatment must be accompanied by 
and does not replace standard supportive respiratory and 
fluid management tor infants and children with severe 
respiratory trad infection. 
Diagnosis: 

RSV infection should be documented by a rapid 
diagnostic method such as demonstration of viral antigen 
in respiratory trad secretions by immunofluorescence^* 
or ELISA^ before or during the first 24 hours of treatment. 
Ribavirin aerosol is indicated only for Iwer respiratory tract 
infection due to RSV Treatment may be initiated while 
awaiting rapid diagnostic test results. However, treatment 
should not be continued without documentation of RSV 
infection. 

CONTRAINDICATIONS: 

Ribavirin is contraindicaled in women or girls who are 
or may become pregnant during exposure to the drug. 
Ribavirin may cause fetal harm and respiratory syncytial 
virus infection is selMimited in this population. Ribavirin 
IS not compldely cleared from human blood even four 
«ei<s after administration. Although there are no pertinent 
human data, ribavirin has been found to be teratogenic 
and/or embryolethal in nearly all species in which it has 
been tested . Teratogenicity was evident after a single oral 
dose ol 25 mg/kg in the hamster and after daity oral doses 
of 10 mg/kg in the rat Malformations of skull, palate, eye, 
law, skeletpn. and gastrointestinal trad were noted in 
animal studies. Survival of fetuses and offspring was 
reduced. The drug causes embryolethality in the rabbit at 
daily oral dose levels as low as 1 mg/kg 

WARNINGS: 

Ribavirin administered by aerosol produced cardiac 
lesions in mice and rats after 30 and 36 mg/kg. respectively, 
for 4 weeks, and after oral administration in monkeys at 120 
and rats at 154 to 200 mg/kg for 1 to 6 months. Ribavirin 
aerosol administered to dei«loping ferrets at 60 mg/kg for 
10 or 30 days resulted in inflammatory and possible 
emphysematous changes in the lungs. Proliferative 
changes were seen at 131 mg/kg for 30 days. The signifi- 
cance of these findings to human administration is 
unknown 

Ribavirin lyophilized in 6 gram vials is intended for use 
as an aerosol only 

PRECAUTIONS: 
General: 

Patients with lower respiratory tract infection due to 
respiratory syncytial virus require optimum monitoring and 
attention to respiratory and fluid status 
Drug Interactions: 

Interactions of ribavirin with other drugs such as digoxin, 
bronchodiiators. other antiviral agents, antibiotics, or anti 
metabolites has not been evaluated Interference by 



ribavirin with laboratory tests has not been evaluated 
Carcinogenesis, mutagenesis. Impairment of 
fertility: 

Ribavirin induces cell transformation in an (^ vitro mam- 
malian system (Balb/C3T3 cell line). Hwever in vivo carcin- 
ogenicity studies are incomplete. Results thus far. though 
inconclusive, suggest that chronic feeding of ribavirin to 
rats at dose levels in the range d 16-60 mg/kg body weight 
can induce benign mammary pancreatic, pituitary and 
adrenal tumors. 

Ribavirin is mutagenic to mammalian (L5178Y) cells in 
culture Results of microbial mutagenicity assays and a 
dominant lethal assay (mouse) were negative. 

Ribavirin causes testicular lesions (tubular atrophy) in 
adult rats at oral dose levels as low as 16 mg/kg/day (lower 
doses not tested), but fertility of nbavirin-treated animals 
(male or female) has not been adequately investigated. 
Pregnancy: 

Teratogenic Effects: Pregnancy Category X See "Con 
traindications" section 

Nursing Mothers: Use of nbavinn aerosol in nursing 
mothers is not indicated because RSV infedion is self- 
limited m this population. Ribavirin is toxic to lactating 
animals and their offspring It is not known whether the 
drug IS excreted in human milk 
ADVERSE REACTIONS: 

Approximately 200 patients have been treated with 
ribavirin aerosol in controlled or uncontrolled clinical 
studies. 

Pulmonary fundion significantly deteriorated during 
ribavirin aerosol treatment m six of six adults with chronic 
obstructive lung disease and in tour of six asthmatic adults. 
Dyspnea and chest soreness were also reported in the 
latter group Minor abnormalities in pulmonary function 
were also seen in healthy adult volunteers. 

Several serious adverse events occurred in severely ill 
infants with life-threatening underlying diseases, many of 
whom required assisted ventilation The role ol ribavirin 
aerosol in these events is indeterminate. The following 
events were associated with ribavirin use. 
Pulmonary - Worsening of respiratory status, bacterial 
pneumonia, pneumothorax, apnea, and ventilator 
dependence 

Cardiovascular : Cardiac arrest, hypotension, and digitalis 
toxicity 

There were 7 deaths during or shortly after treatment 
with ribavirin aerosol. No death was attributed to ribavirin 
aerosol by the investigators. 

Some subjects requiring assisted ventilation have 
experienced serious difficulties, which may jeopardize ade- 
quate ventilation and gas exchange Precipitation of drug 
within the ventilatory apparatus, including the endotracheal 
tube, has resulted in increased positive end expiratory 
pressure and increased positive inspiratory pressure. 
Accumulation ot fluid in tubing ("rain out") has also been 
noted. 

Although anemia has not been reported with use of the 
aerosol, it occurs frequently with oral and intravenous 
ribavirin, and most infants treated with the aerosol have 
not been evaluated 1 to 2 weeks post-treatment when 
anemia is likely to occur Reticulocytosis has been reported 
with aerosol use. 

Rash and conjunctivitis have been associated with the 
use of ribavirm aerosol. 
Overdosage: 

No overdosage with ribavirin by aerosol administration 
has been reported in the human The LDm in mice is 

2 gm orally Hypoactivity and gastrointestinal symptoms 
occurred In man, ribavirin is sequestered in red blood cells 
for weeks after dosing. 

DOSAGE AND ADMINISTRATION 

Before use, read thoroughly the Viratek Small Particle 
Aerosol Generator (SPAG) Model SPAG-2 Operator's 
Manual for small particle aerosol generator operating 
instructions. 

Treatment was effective when instituted within the first 

3 days ol respiratory syncytial virus lower respiratory tract 
infection ^ Treatment early in the course of severe lower 
respiratory tract inledion may be necessary to achieve 
efficacy. 

Treatment is carried out for 12-18 hours per day for at 
least 3 and no more than 7 days, and is part of a total treat- 
ment program. The aerosol is delivered to an infant oxygen 
hood from the SPAG-2 aerosol generator Administration 
by face mask or oxygen tent may be necessary if a hood 
cannot be employed (see SPAG-2 manual). Hovrever. the 
volume of distribution and condensation area are larger 
in a tent and efficacy of this method of administering the 
drug has been evaluated in only a small number of patients 
Ribavirin aerosol is not to be administered with any other 
aerosol generating device or together with other 
aerosolized medications. Ribavirin aerosol should not be 
used for patients requiring simultaneous assisted 
ventilation (see Boxed Warnings) 

Virazole is supplied as 6 grams of lyophilized drug per 
100 ml vial tor aerosol admmistration only By stenle 
technique, solubilize drug with sterile USP water for injec 
tion or inhalation in the 100 ml vial Transfer to the clean, 
sterilized 500 ml widemouth Erienmeyer llask (SPAG-2 
Reservoir) and lurther dilute to a Imal volume ol 300 ml 



with sterile USP water tor injection or inhalation The final 
concentration should be 20 mg/ml Important: This water 
should not have had any antimicrobial agent or other sub- 
stance added. The solution should be inspected visually 
for particulate matter and discoloration prior to administra- 
tion Solutions that have been placed in the SPAG-2 unit 
should be discarded at least every 24 hours and when the 
liquid level is low before adding newly reconstituted 
solution 

Using the recommended drug concentrahon of 
20 mg/ml ribavirin as the starting solution in the drug 
reservoir of the SPAG unit, the average aerosol 
concentration for a 12 hour period would be 190 micro- 
grams/liter {0,19 mg/l) of air 

HOW SUPPLIED: 

Virazole® (ribavirin) Aerosol is supplied in 100 ml glass 
vials with 6 grams of sterile, lyophilized drug which is to 
be reconstituted with 300 ml sterile water for injection or 
sterile water for inhalation (no preservatives added) and 
administered only by a small particle aerosol generator 
(SPAG-2) Vials containing the lyophilized drug powder 
should be stored in a dry place at 15'25°C {59-78°F), 
Reconstituted solutions may be stored, under sterile 
conditions, at room temperature (20-30X. 68-86°f^ for 24 
hours Solutions which have been placed in the SPAG-2 
unit should be discarded at least every 24 hours. 

REFERENCES: 

1 Hruska JF Bernstein JM. Douglas Jr, RG, and Hall CB 
Effects of ribavirin on respiratory syncytial virus in vilro 
Antimicfob Agents Chemother 1980:17770775. 

2 Hruska JR Morrow PE, Suffin SC and Douglas Jr . RG. 
tn VIVO inhibition of respiratory syncytial virus by ribavinn. 
Anlimicrob Agents Chemother 1982;21-125-130 

3 Taber LH, Knight V Gilbert B£, McClung HW et al 
Ribavirin aerosol treatment of bronchiolitis associated 
with respiratory tract infection in infants. Pediatrics- 
1983;72:613-618. 

4, Hall CB, McBride JT Walsh EE, Bell DM et al. Aero- 
solized ribavirin treatment of infants with respiratpry 
syncytial viral infection. A/ f/Tff/J/Wetf 1983:30814437 

5. Hendry RM. Mcintosh K, Fahnestock ML, and Pierik LT 
Enzyme-linked immunosorbent assay for detection of 
respiratory syncytial virus infection. J Clin Microbiol. 
1982:16:329-33, 

ADVERTISING REFERENCES: 

1, Hall CB. Update in Upstate 1990; 1-11 

2, Adapted from "Policy Statement. Ribavirin Therapy 
of Respiratory Syncytial Virus!' American Academy 
of Pediatrics Committee on Infectious Diseases, 
1986-87 

The appearance of the name American Academy 
ot Pediatrics does not constitute a guarantee or 
endorsement of the product advertised or the 
claims made. 

.^ 1991 ICN Pharmaceuticals 




D 
B 



ICN Pliarmaceutlcals, Inc. 

ICN Plaza 

3300 Hyland Avenue 
Costa Mesa, CA 92626 
Telephone: (714) 545-0100 



TEST YOUR RADIOLOGIC SKILL 



3. Hadeed HA, Braun TW. Paralysis of the hemidiaphragm 
as a complication of internal jugular vein catheterization. 
J Oral Maxillofac Surg 1988;46:409-411. 

4. Stock MC, Downs JB. Transient phrenic nerve blockade 
during internal jugular vein cannulation using the 
anteriolateral approach. Anesthesiology 1982;57:230-233. 

5. Moore KL. Clinically oriented anatomy. Baltimore: 
Williams & Wilkins, 1980:96,11 18,1 140. 

6. Obel IWP. Transient phrenic nerve paralysis following 
subclavian venipuncture. Anesthesiology 1970;33:369- 
370. 

7. Feliciano DV, Mattox KL, Graham JM. Major compli- 
cations of percutaneous subclavian vein catheters. Am 
J Surg 1979;138:869-874. 

8. Goldenheim PD, Kazemi H. Cardiopulmonary monitoring 
of critically ill patients. N Engl J Med 1984;31 1:776- 
778. 

9. Puri VK, Carlson RW, Bander JJ, Weil MH. Compli- 
cations of vascular catheterization in the critically ill: A 
prospective study. Crit Care Med 1980;8:495-499. 

10. Senagore A, Waller JD, Bonnell BW. Pulmonary artery 
catheterization: A prospective study of internal jugular 
and subclavian approaches. Crit Care Med 1987;15:35- 
37. 

11. Paskin DL, Hoffman WS, Tuddenham WJ. A new 
complication of subclavian vein catheterization. Ann Surg 
1974;179:266-268. 

12. Barash PG, Nardi D, Hammond G. Catheter-induced 
pulmonary artery perforation: Mechanisims, management. 



and modifications. J Thorac Cardiovasc Surg 1981;82: 
5-12. 

13. Elliot CG, Zimmerman GA, Clemmer TP. Complications 
of pulmonary artery catheterization in the care of critically 
ill patients. Chest 1979;76:647-652. 

14. Sprung CL, Jacobs W, Caralis PV. Ventricular arrhyth- 
mias during Swan-Ganz catheterization of the critically 
ill. Chest 1981;79:413-415. 

15. Shah KB, Rao TLK, Laughlin S, El-Etr AA. A review 
of pulmonary artery catheterization in 6245 patients. 
Anesthesiology 1984;61:271-275. 

16. Lapin ES, Murray JA. Hemoptysis with flow-directed 
cardiac catheterization (letter). JAMA 1972:220:1246. 

17. O'Toole JD, Wurtzbacher JJ, Wearer NE. Pulmonary 
valve injury and insufficiency during pulmonary-artery 
catheterization. N Engl J Med 1979:301:1 167-1 168. 

18. Boscoe MJ, Delange S. Damage of the tricuspid valve 
with a Swan-Ganz catheter. Br Med J 1981:283:346-347. 

19. Doering RB, Stemmer EA, Connolly JE. Complications 
of indwelling venous catheters with particular reference 
to catheter embolus. Am J Surg 1 967; 1 14:259-266. 

20. Abemathy WS. Complete heart block caused by the Swan- 
Ganz catheter. Chest 1974;65:349. 

21. Drachler DH, Koepke GH, Weg JG. Phrenic nerve injury 
from subclavian vein catheterization: Diagnosis by 
electromyography. JAMA 1976;236:2880-2881. 

22. Pare JAP, Eraser RG. Synopsis of diseases of the chest. 
Philadelphia: WB Saunders Co, 1983:737-740. 

23. Hinshaw HC, Murray JF. Diseases of the chest. 4th ed. 
Philadelphia: WB Saunders Co, 1980:921. 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



225 



Deaigned to E>elJve 

Directly to th 



"V 



T 



.With the AeroVent device, you dedicate without compromising the integrity of the ventilator 
circuit and without taking valuable tiqie for Small Volume Nebulizer (S VN) hook-ups or 
circuit disconnections . The AeroVent device incorporates many design innovations 

including features of the Aerochamber" aerosol delivery system.— 



When actuated, the therapist 
can see the MDI spray 

/ directed at an angle to allow 
minimum impaction on the 
walls while allowing the 

I plume to mature tKus 
achieving the greatest 

. deposition in the 4- 
patient's lungs. 




Metered Dose Inhaler Actuator-Adapters: A Comparison of Particle Size and Drug Delivery Through an Endotracheal Tube - Richard P. Larson, RRT et all - Resp. Care. Nov '89 Vol 34 No 1 1 



The AeroVent device is designed for convenient single patient use. 



Aerosol Medications 

^tilated Patient. 



The AeroVent device includes a built- 

j in snap closure to keep the AeroVent 

collapsed while in place and not in 

use, allowing unrestricted gas flow 

through the breathing circuit. 



J' 

IT 



The AeroVent holding j 
chamber can be latched I 
when collapsed in the ! 

circuit, ready for the next 
time you need to medicate --^- 
the patient. Simply unlatch, 
expand the AeroVent device 
and actuate the aerosol — ~ 
medication from the me- I 
tered dose inhaler (MDI). \ 



The AeroVent device has 
been tested and proven 
to deliver 4.5 times greater * 
deposition than a standard 
SVN to the mechanically 
ventilated patient. * ■ 




• Fuller HD, Dolovich 
MB, Posmituck G, Wong 
Pack W. and Newhouse 
MT. Pressurized Aerosol 
versus Jet Aerosol Deliv- 
ery lo Mechanically 
Ventilated Patients: 
Comparison of dose to 
the lungs. Am Rev 
Respir Dis; 141:440-444 



-h 



Graphic Representation of Actual Lung Deposition Data. 



vtv 



'»a«v' 



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Circle 142 on reader service card 



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Listings and Reviews of Books and Otiier Media 

Note to publishers: Send review copies of books, films, tapes, and software to 
Respiratory Care. 1 1030 Abies Lane, Dallas TX 75229. 



Books, Films, 
Tapes, & Software 



Asthma Resources Directory, by 

Carol Rudoff MA. Soft cover, 320 
pages. Allergy Publications, PO Box 
640, Menlo Park CA 94026. $29.95 
plus $2.00 shipping (U.S. dollars). 

In her introduction, the author 
states that this book provides a wide 
variety of resources and products, 
with 2,586 listings. I do not think that 
I have ever seen such a collection of 
information in one resource book. 

The book is organized into four 
sections: Section I — Asthma Triggers, 
Section n — Patient Support, Section 
III — Medical Care, and Section FV — 
Information Resources. 

In Asthma Triggers, the author 
begins with lists of months of the year, 
types of pollen, and states in which 
the pollens are found. A stronger 
beginning might have been a good 
introduction to what asthma is, how 
it is described medically (reversible 
airways obstruction), what that 
means, and what the various triggers 
are known to be. We have noted with 
patients in our hospital that asthmatic 
patients have a problem with the 
inferences that everyone with asthma 
has allergies and that everyone with 
allergies has asthma. 

The information on filters, humid- 
ifiers, and similar devices is exten- 
sive. A diagram showing how to 
calculate the volume (number of cubic 
feet) in a room might be helpful to 
one planning to purchase a home 
filtering system. Placing the descrip- 
tion of a device immediately before 
specific product information would 
also make the information clearer to 
the reader. The information contained 
in the chapters Living with the Air 
in Your Home and Controlling Your 
Home Environment could have been 
combined into one better-organized 
section. Regardless of the shortcom- 
ings in organization and the confusion 
it caused me, there is still an incred- 
ible amount of good information in 
these chapters. 



The chapter on traveling with 
asthma has valuable information for 
anyone who has a chronic disease that 
requires preplanning a trip. Informa- 
tion listed under In an Emergency 
should be categorized. Putting Epi- 
Pen information in the same area as 
Emergency Prescription Service 
(provides a toll-free number to get 
prescriptions filled) just didn't make 
sense to me. 

It has been our experience that 
patients with asthma want to read 
everything they can get their hands 
on. The Asthma Resources Book 
contains names, addresses, and tele- 
phone numbers for hundreds of 
groups that produce written, audio, 
and video materials related to this 
disease. For clinicians looking for 
patient education material, take this 
advice Don't 'reinvent the wheel.' 
Get this book, send off for all the 
free (or cheap) literature, and choose 
the best for use with your patients. 

Medical Care contains information 
on pulmonary function equipment 
that may be useful to the technician 
but confusing to the layman. It might 
be more helpful to know the Whats 
and Whys about testing and how that 
information is used to determine the 
individualized treatment plan. Much, 
much more information could be 
given about self-monitoring. This 
whole book is talking about a proac- 
tive health model, and many clini- 
cians believe that daily measurement 
of peak flow is one of the most 
important things that the patient can 
do to help gain control, instead of 
letting the disease be in control. 

Pictures and diagrams are always 
helpful when they are simple and 
directly tied to written descriptions. 
Pictures of a typical air compressor 
and a disposable nebulizer would 
have been good additions to the 
section on adapters and respiratory 
devices. 

Information Sources provides some 
of the most valuable information in 
the book. The resources are catego- 



rized — organizations, health lines, 
directories, newsletters, and adult and 
childrens' reading materials. Under 
Libraries, a statement about what to 
ask for when you call your public 
library might suffice. Almost every 
community has a library and a 
mechanism within that library, no 
matter how small, to provide re- 
quested information. The Database 
listing was unclear to me. I am not 
computer literate and would need 
more information to make use of it. 

Insurance was one of the best 
chapters and contained excellent 
information related to the very issues 
that persons with asthma and other 
so-called pre-existing conditions are 
struggling with. Remembering the 
differences among PPOs, HMOs, and 
IPAs is a challenge for anyone! 

Undoubtedly, equipment manufac- 
turers and pharmaceutical companies 
were asked to provide product infor- 
mation for this book, and, certainly, 
a book like this could not be compiled 
without their help. But, regardless of 
disclaimers, it was hard to miss the 
advertising contained in these 320 
pages. There were reminders on 
almost every other page for the reader 
to let companies know they had been 
referred by the Asthma Resources 
Directory. That was distracting and 
tiresome. 

The author is to be congratulated 
for putting together a complete 
resource. This book can be of great 
benefit to the clinician who is looking 
for just the right information to share 
with patients and their parents. 

Gretchen Lawrence RRT 

Manager 

Asthma & Pulmonary 

Rehabilitation Center 

Baylor University Medical Center 

Dallas, Texas 



RESPIRATORY CARE MARCH '91 • Vol. 36 No 3 



229 




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Letters on topics of current interest or commenting on material in Respiratory Care will be considered for publication. 
The Editor may accept or decline a letter or edit it without changing the author's views. The content of letters 
as published may simply reflect the author's opinion or interpretation of information — not standard practice or 
the Journal's recommendation. Authors of criticized material will have the opportunity to reply in print. No anonymous 
letters can be published. Type letter double-spaced, mark it "For publication," and mail to Respiratory Care 
Journal, 1 1030 Abies Lane, Dallas TX 75229. 



Letters 



PCIRV: Panacea or Auto-PEEP— A 
Response Based on 
Clinical Experience 

We were disappointed when we read the 
editorial by Kacmarek and Hess in the 
October 1990 issue of Respiratory Care.' 
The editorial builds its case with what we 
believe to be some misrepresentation of 
previously published data. Although there 
is reference to one of the authors having 
experience with PCIRV in a laboratory 
model, there is no mention of clinical 
experience with the mode to substantiate 
the authors" point of view. We would like 
to clarify several points in the editorial that 
easily could be misconstrued. 

The editorial stated that no control group 
was used during any of the studies. In the 
study conducted at our institution by 
Abraham and Yoshihara,- the patients 
themselves served as their own control. We 
believe that a comparison of the effects of 
two modes of mechanical ventilation is best 
achieved on the same patient, whereby the 
number of variables (eg, the disease state 
and APACHE score) are minimized. To use 
a separate group of patients as a control 
would have introduced additional variables, 
diminishing the significance of any 
correlations. 

The authors of the editorial stated, 
"Further, we believe that the same effect 
might have occurred if the authors used 
higher levels of PEEP with conventional 
volume-control ventilation! " ' This comment 
may be true, but one must remember that 
the goal of PCIRV is not only to improve 
oxygenation, but to do so by using lower 
peak inspiratory pressures and lower 
inspired oxygen concentration. The respi- 
ratory rate, inspiratory pressure, and I-E 
ratios are manipulated to intentionally 
generate auto-PEEP. The auto-PEEP 
created is then used to replace the high levels 
of applied (set) PEEP. Thus, the set PEEP 
can be greatly reduced or eliminated. In 
addition, the change in pressure (AP) is 
reduced, which theoretically reduces the 
negative effect of shear forces.^ 

In PCIRV the set pressure and inspiratory 
flow are reached almost immediately. The 
inspiratory pressure is maintained for the 
duration of the set inspiratory time exposing 
pathologic alveoli to the peak inspiratory 



pressure (which is lower than conventional) 
for a longer fwriod of time. This process 
promotes recruitment based on a time factor 
(ie, more time is dedicated to a pressure 
level that exceeds critical pressure). As the 
inspiratory flow encounters back pressure, 
the flow decelerates, which not only assists 
in maintaining the peak inspiratory pressure 
at a constant level, but also, in conjunction 
with the sustained inspiratory pressure, aids 
in the recmitment of unstable lung units 
and may provide better distribution of gas.-*- 
^ Therefore, auto-PEEP or high levels of 
set PEEP may not be the only alternatives 
to increased Fio, for improving oxygena- 
tion. PCIRV may provide a multifactoral 
alternative to improve oxygenation and 
ventilation in patients who are refractory 
to conventional therapy. 

Kacmarek and Hess stated that auto- 
PEEP was not recognized or measured in 
the studies cited. Furthermore, they 
criticized that all of the papers on PCIRV 
failed to acknowledge that short expiratory 
times produce air trapping and auto-PEEP. 
The studies by Tharratt et aF and Abraham 
and Yoshihara- make reference to the fact 
that expiratory flow was monitored with 
an oscilloscope or strip recorder. The 
monitors were utilized to ensure that the 
end expiratory flow did not reach zero prior 
to triggering of the next breath. Although 
auto-PEEP is not mentioned as being 
recorded in any of the articles, the 
monitoring of the end-expiratory flow 
indicated that auto-PEEP was being 
monitored and intentionally generated to 
replace the applied PEEP. In the article by 
Abraham and Yoshihara,- end-expiratory 
pressure was measured and adjusted to 
maintain the same level as the PEEP utilized 
during volume-control ventilation. End- 
expiratory pressure is a more applicable 
term to use because it represents the total 
PEEP to which the patient is exposed. 

Another criticism was "the presence of 
auto-PEEP also requires increased patient 
effort to trigger assisted breaths, which 
might be part of the reason that sedation 
and paralysis are necessary during PCIRV." 
The patient is sedated and paralyzed on 
PCIRV because the inspiratory-to- 
expiratory ratio is reversed, presenting an 
unnatural (and uncomfortable) pattern of 
breathing. To receive full benefit of the 



PCIRV mode, patients must be prevented 
from disrupting the preset I-E ratio. 
Paralysis prevents the patient from 
'bucking,' assisting, or, in any other way, 
disrupting the preset I-E ratio. Because 
Kacmarek and Hess are well-respected, 
many readers may regard their editorials 
as being accurate, well-researched, and, 
therefore, applicable in the clinical setting. 
Because many readers may be influenced 
by these two j authors, two unfortunate 
situations could result (1) patients who 
are appropriate candidates for PCIRV 
could be denied the benefit of the mode, 
and (2) studies with PCIRV could be 
deterred and the subsequent value of the 
knowledge and clinical experience lost. 

Although we agree with the authors' 
suggestion that the mode be used with 
caution, we are not only surprised but also 
disappointed that they wrote such an 
adamant editorial without properly citing 
published data and without citing personal 
clinical experience with PCIRV to substan- 
tiate their views. 

Edward Abraham MD 

Associate Professor 
Department of Medicine 

Gary Yoshihara BA RRT 

Clinical Specialist 

Medical Intensive Care Unit 

Division of Pulmonary Medicine 

and Critical Care 

John Wright BS RRT 

Assistant Director of Respiratory Care 

UCLA Medical Center 
Los Angeles, California 



REFERENCES 



1. Kacmarek RM, Hess D. Pressure- 
controlled inverse-ratio ventilation: 
Panacea or auto-PEEP? (editorial). 
RespirCare 1990:35:945-948. 

2. Abraham E, Yoshihara G. Cardiores- 
piratory effects of pressure controlled 
inverse ratio ventilation in severe res- 
piratory failure. Chest 1989;96: 
1356-1359. 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



231 



LETTERS 



3. Lachmann B, Danzmann E, Haendly 
B, Jonson B. Ventilator settings and 
gas exchange in respiratory distress 
syndrome. In: Prakash O, ed. Applied 
physiology in clinical respiratory care. 
Boston: Martinus Nijhoff, 1982: 
141-176. 

4. Gurevitch MJ, VanDyke J, Young ES, 
Jackson K. Improved oxygenation 
with lower peak airway pressures in 
severe adult respiratory distress 
syndrome: Treatment with inverse 
ratio ventilation. Chest 1988;94: 
755-762. 

5. Al Saady N, Bennett ED. Decelerating 
inspiratory flow waveform improves 
lung mechanics and gas exchange in 
patients on intermittent positive- 
pressure ventilation. Intensive Care 
Med 1985;11:68-75. 

6. Connors AF, McCaffree DR, Gray 
BA. Effect of inspiratory flow rate 
on gas exchange during mechanical 
ventilation. Am Rev Respir Dis 
1981;124:537-543. 

7. Tharratt RS, Allen RP, Albertson TE. 
Pressure controlled inverse ratio 
ventilation in severe adult respiratory 
failure. Chest 1988;94:755-762. 

Kacmarek and Hess respond: 

Abraham et al imply in their response 
to our editorial that we developed our 
concerns regarding PCIRV purely on 
theoretical grounds. Although we chose to 
argue our point based on published data, 
our concern initially resulted from our 
anecdotal clinical experience. It is true that 
we may be less capable of applying this 
ventilatory technique than Abraham et al, 
but our results have been much less 
promising than theirs. The frequency of 
hemodynamic compromise and the devel- 
opment of barotrauma as well as the 
magnitude of auto-PEEP developed in our 
experience far exceeds that noted in the 
literature. We have anecdotally noted a far 
better response in our patients with 
conventional ventilation and PEEP than 
with PCERV. 

We indicated in our editorial' that no 
control group was used by Abraham and 
Yoshihara (1989);^ however, they indicate 
in their letter that patients themselves were 
used as controls. We must question these 
authors' understanding of a controlled 



clinical study. This study' did not control 
for a single variable between the two 
treatment modalities except for end- 
expiratory pressure. In addition, no stated 
protocol for the setup of conventional 
ventilation with PEEP is presented. We ask 
the authors to compare these methods in 
the 1989 study^ to those in their recently 
published study on pressure control 
ventilation. 3 In their 1990 study, the 
application of volume-limited and pressure- 
controlled ventilation was controlled 
adequately enough to allow the authors' 
results (an increase in PO2) to be attributed 
to the use of pressure control. 

Abraham et al state that auto-PEEP was 
used to replace the high levels of applied 
PEEP. This we believe is exactly what 
occurred in their study; however, no 
measure of the auto-PEEP that developed 
as the I:E was reversed is provided. They 
do pK)int out in their introduction that 
PCIRV is associated with auto-PEEP, but 
make no further reference to its develop- 
ment. Abraham et al argue that they 
monitored expiratory flow and terminated 
expiration before expiratory flow fell to 
zero. We agree that this implies the presence 
of auto-PEEP. However, in no way does 
this indicate the magnitude of auto-PEEP. 
The use of the term end-expiratory pressure 
and applied PEEP by Abraham et al are 
confusing to us. They imply that end- 
expiratory pressure represents total PEEP. 
We are unaware of the use of this term 
to represent auto- plus applied PEEP nor 
do Abraham et al define how total PEEP 
can be determined without the direct 
measurement of auto-PEEP. In addition, as 
we previously indicated, equal levels of 
auto-PEEP and applied PEEP may not 
produce the same physiologic response. 

The fact that the inspiratory-to-expiratory 
pressure differential that alveoli are exposed 
to during volume-limited ventilation with 
nonnal I:E is higher than that occurring 
during PCIRV has never been demon- 
strated. However, we agree with Abraham 
et al that the use of pressure control 
ventilation at normal ratios may result in 
improved distribution of inspired gas and 
better gas exchange.' However, we believe 
that additional research is necessary before 
any conclusion can be drawn. 

Two issues confuse the discussions of 
the efficiency of PCIRV. One is I:E, about 
which we believe no data exist supporting 



the use of inversed ratios over conventional 
ratios. The other is the use of pressure 
control ventilation at conventional ratios. 
These two issues need to be separated and 
studied independently in order to resolve 
the questions raised regarding PCIRV. We 
do encourage controlled systematic study 
of PCIRV, but we must still caution 
practitioners about the use of inverse-ratio 
ventilation until more complete data are 
available. 

Robert M Kacmarek PhD RRT 

Assistant Professor 

Department of Anesthesiology 

Harvard Medical School 

Director 

Respiratory Care 

Massachusetts General Hospital 

Boston, Massachusetts 

Dean Hess MEd RRT 

Assistant Director of 
Clinical Research York Hospital 

Instructor 

Respiratory Care Program 

York Hospital 

and York College of Pennsylvania 

York, Pennsylvania 

REFERENCES 

1. Kacmarek RM, Hess D. Pressure- 
controlled inverse-ratio ventilation: 
Panacea or auto-PEEP? (editorial). 
Respir Care 1990;35:945-948. 

2. Abraham E, Yoshihara G. Cardiores- 
piratory effects of pressure controlled 
inverse ratio ventilation in severe 
respiratory failure. Chest 1989; 
96:1356-1359. 

3. Abraham E, Yoshihara G. Cardiores- 
piratory effects of pressure control 
ventilation in severe respiratory 
failure. Chest 1990;98:1445-1449. 



Call for 

1991 

Open Forum 

Abstracts 



page 235 



232 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



Notices 



Notices of competitions, scholarships, fellowships, examination dates, new education programs, and the like will 
be listed here free of charge. Items for the Notices section must reach the Journal 60 days before the desired 
month of publication (January 1 for the March issue, February 1 for the April issue, etc). Include all pertinent 
information and mail notice to Respiratory Care Notices Dept, 1 1030 Abies Lane, Dallas TX 75229. 



PSRC AWARDS 

The Pennsylvania Society for Respiratory Care through its Scholarship Literary Award 
Program is offering awards of $350 plus 1-year free AARC memberships to three 
active practitioners and three students enrolled in accredited respiratory therapy programs. 
Applicants must be Pennsylvania residents. Application and manuscript deadline is 
March 22, 1991. Contact Dennis Wimer at 800 346-4789, ext 5341. 

AARC SUMMER FORUM 

The Westin, Vail, Colorado, July 12-14, 1991 

AARC ANNUAL CONVENTION SITES & DATES 

1991 — Atlanta, Georgia, December 7-10 
1992 — San Antonio, Texas, December 12-15 
1993 — Nashville, Tennessee, December 11-14 
1994 — Las Vegas, Nevada, December 12-15 
1995 — Orlando, Florida, December 2-5 



THE NATIONAL BOARD FOR RESPIRATORY CARE 
1991 Examination and Fee Scliedule 



CRTT Examination 



EXAMINATION DATE: 
Applications Accepted Beginning: 
Application Deadline: 

EXAMINATION DATE: 
Applications Accepted Beginning: 
Application Deadline: 

EXAMINATION DATE: 
Applications Accepted Beginning: 
Application Deadline: 



MARCH 9, 1991 

November 1, 1990 

January 1, 1991 

JULY 20, 1991 

March 1, 1991 

May 1, 1991 

NOVEMBER 9, 1991 

July 1, 1991 

September 1, 1991 



CPFT Examination 

EXAMINATION DATE: JUNE 1, 1991 

Applications Accepted Beginning: December 1, 1990 

Application DeadHne; April 1, 1991 



RRT Examination 

EXAMINATION DATE: 

Applications Accepted Beginning: 
Application Deadline: 

EXAMINATION DATE: 

Applications Accepted Beginning: 
Application Deadline: 



JUNE 1, 1991 

December 1, 1990 

February 1, 1991 

DECEMBER 7, 1991 

June 1, 1991 

August 1, 1991 



Perinatal/Pediatric Respiratory Care 
Specialty Examination 

EXAMINATION DATE: MARCH 9, 1991 

Applications Accepted Beginning: July 1, 1990 

Application Deadline: November 1, 1990 

Application Fee: $150 



RPFT Examination 

EXAMINATION DATE: DECEMBER 7, 1991 

Applications Accepted Beginning: July I, 1991 

Application Deadline: September 1, 1991 



Entry Level CRTT- 
Entry Level CRTT- 



Fee Schedule 

-new applicant: 
-reapplicant: 



RRT Written and Clinical Simulation — 

new applicant: 
Written Registry Only new applicant: 
Written Registry Only reapplicant: 
Clinical Simulation Only new and reapplicant: 



Entry Level CPFT- 
Entry Level CPFT- 

Advanced RPFT- 
Advanced RPFT- 



-new applicant: 
-reapplicant: 

-new applicant: 
-reapplicant: 



CRTT Recredentialing: 

RRT Recredentialing: 

Written Registry Examination 
Clinical Simulation Examination 

CPFT Recredentialing: 

RPFT Recredentialing: 

Membership Renewal 

CRTT/RRT/CPFT/RPFT 



$ 75.00 
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$175.00 
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8310 Nieman Road • Lenexa, Kansas 66215 • (913) 599-4200 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



233 



Calendar 
of Events 



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 month two months preceding the month 
you wish the ad to run. Submit copy and insertion orders to: Calendar of Events, Respiratory Care, 
1 1030 Abies Lane, Dallas TX 75229. 



AARC & AFFILIATES 



March 14-15 in Newport, Rhode Island. The RISRC 

presents "The Newport Challenge: Sailing into the 90s." 
Topics include transtracheal oxygenation, ventilator 
weaning, humor as therapy, microphysiology of 
asbestosis, and cystic fibrosis. Workshops, social 
activities and a large exhibit complete the program. 
Contact Skip Bangley RRT, St Joseph Hospital, 21 Peace 
St, Providence RI 02907 or call (401) 456-4174. 

March 25-27 in Philadelphia, Pennsylvania. The PSRC 

presents its 26th Annual Conference and Exhibition at 
the Adam's Mark Hotel. This year's theme is "The Next 
Generation," featuring a space-age trek into the realm 
of respiratory care and cardiovascular technology. 
Contact Betsy Schneck, (2 1 5) 829-3578 or Kathy Yandle, 
(215)453-4517. 

April 3-5 in Nashville, Tennessee. The TSRC presents 
its Annual Convention and Exhibition at the Vanderbilt 
Plaza Hotel. This year's theme is Everything Under The 
Sun in '91, and focuses on current trends and all phases 
of cardiopulmonary care. For registration information 
contact Collen Schabacker at (6 1 5) 384- 1 569. For exhibit 
information contact Candy Partee at (615) 449-0500. 

April 10-12 in Bismarck, North Dakota. A New Decade 
of Strength in Respiratory Care is the theme for NDSRC's 
annual convention. Topics include nutrition studies, adult 
and neonatal critical care issues, and management 
strategies. For more information, call (701) 224-7870. 

April 17-19 in Osage Beach, Missouri. The Missouri 
Society for Respiratory Care presents its 20th Annual 
Meeting at the Tan-Tar-A resort. Lake of the Ozarks. 
Speakers include Neil Mclntypre MD and Sheldon Braun 
MD Contact Jim Pattinson RRT, at (417) 885-2800. 

May 1-3 in Rapid City, South Dakota. Rapid City 
Regional Hospital hosts the annual convention of the 
SDSRC. Featured speakers (including WJ O'Donohue 
Jr MD, Robert Kacmarek PhD RRT, and Anthony Talbert 
MD) discuss neonatal, pediatric, and adult critical care 
issues. Contact Terry Anderson RRT, Respiratory Care 
Department, 1-800-232-9287. 

May 16-17 in Wichita, Kansas. The KRCS presents 
its 14th Annual Education Seminar at the Airport Hilton. 
Topics range from future directions of the profession 
to PPT, asthma, and critical care issues. Scheduling 
allows for golf, exhibits and a great time for everyone. 
Contact Don Richards, MS RRT, VA Medical Center, 
(316) 685-2221 for more information. 



May 28-31 in Jekyll Island, Georgia. The Georgia/ 
South Carolina Region VI presents its 15th Annual 
Conference and Assembly at the Holiday Inn, Jekyll 
Island. Contact Mike Payne RRT, 730 South Pleasantburg 
Dr, Suite 525, Greenville SC 29607. (803) 879-0130. 

June 12-14 in Vail, Colorado. The CSRC State 
Convention's theme "Bringing It All Together" focuses 
on the crossover between hospital and home care. A 
golf tournament is featured for the morning of the 1 2th, 
followed by a barbecue picnic that evening. Contact Jim 
Bowman, Vencor Hosn, 1 920 High St, Denver CO 802 1 8, 
(303)320-5871. 

July 10-12 in Houston, Texas. The TSRC meeting 
features AARC President Patrick Dunne, Kevin Shrake, 
Diane Lewis, Connie Podesta, and Ulf Borg. For 
information contact TSRC Executive Office, PO Box 
5 1 5239, Dallas TX 7525 1 , (2 1 4) 239-8772 or FAX (2 1 4) 
239-6418. 

OTHER MEETINGS 

March 10-13 in Denver, Colorado. The National Jewish 
Center for Immunology and Respiratory Medicine, in 
conjunction with the American College of Chest 
Physicians, presents the 3rd International Conference on 
Pulmonary Rehabilitation and Home Mechanical 
Ventilation, with concurrent workshops on home 
ventilator care and pulmonary rehabilitation, at the 
Denver Hyatt. Contact Adele Gelfand, Conference 
Coordinator, (303) 398-1359. 

April 12-14, Miami to Nassau. Another "Floating 
Seminar" for Health Care Professionals on "Quality 
Assurance — How To Accomplish It." A hands-on 
program. Deadline for reservations — March 15, 1991. 
Contact Dave Robbins at (305) 441-6819. 

May 17-18 in Las Vegas, Nevada. The American Lung 
Association of Nevada sponsors the 6th Annual Southern 
Nevada Respiratory Health Conference at the Sahara 
Hotel. Contact American Lung Association of Nevada, 
PO Box 44137, Las Vegas NV 891 16. (702) 454-2500. 

August 25-September 1, Caribbean Cruise. Cruise the 
Western Caribbean aboard the SS Sea Breeze while 
earning 8 CRCE credits. Topic is "Aid for AIDS." $895 
prepaid includes airfare, cruise, transfers, food, and 
entertainment. Friends and family welcome. Call or write 
Dream Cruises, 10882 LaDona Ave, Garden Grove CA 
92640. 1-800-462-3628. 



234 



RESPIRATORY CARE • MARCH '91 Vol. 36 No 3 



Respiratory Care • OPEN FORUM 



1991 Call for Abstracts 



The American Association for Respiratory Care and its science 
journal, Respiratory Care, invite submission of brief abstracts 
related to any aspect of cardiorespiratory care. The abstracts 
will be reviewed, and selected authors will be invited to present 
papers at the Open Forum during the AARC Annual Meeting 
in Atlanta, Georgia, December 7-10, 1991. Accepted abstracts 
will be published in the November 1991 issue of Respiratory 
Care. Membership in the AARC is not necessary for 
participation. 

Specifications 

An abstract may report (1) an original study, (2) the 
evaluation of a method or device, or (3) a case or case series. 

Topics may be aspects of adult acute care, continuing care/ 
rehabilitation, perinatology/pediatrics, cardiopulmonary 
technology, health occupations education, or management of 
personnel and health-care delivery. The abstract may have been 
presented previously at a local or regional — but not national — 
meeting and should not have been published previously in a 
national journal. 

The abstract will be the only evidence by which the reviewers 
will decide whether the author should be invited to present a 
paper at the Open Forum. Therefore, the abstract must provide 
all important data, findings, and conclusions. Give specific 
information. Do not write such general statements as "Results 
will be presented" or "Significance will be discussed." 

Essential Content Elements 

An original study abstract must include (1) Introduction: 
statement of research problem, question, or hypothesis; (2) 
Method: description of research design and conduct in sufficient 
detail to permit judgment of validity; (3) Results: statement of 
research findings with quantitative data and statistical analysis; 
(4) Conclusions: interpretation of the meaning of the results. 

A method/device evaluation abstract must include (1) 
Introduction: identification of the method or device and its 
intended function; (2) Method: description of the evaluation in 
sufficient detail to permit judgment of its objectivity and validity; 
(3) Results: findings of the evaluation; (4) Experience: summary 
of the author's practical experience or a notation of lack of 
experience; (5) Conclusions: interpretation of the evaluation and 
experience. Cost comparisons should be included where possible 
and appropriate. 

A case report abstract must report a case that is uncommon 
or of exceptional teaching/learning value and must include: (1) 
case summary and (2) significance of case. Content should reflect 
results of literature review. The author(s) should have been 
actively involved in the case and a case-managing physician must 
be a co-author or must approve the report. 



Abstract Format and Typing Instructions 

An optical scanner will be used to process abstracts. First 
line of abstract should be the title. Title should explain content. 
Type or electronically print the abstract double-spaced on plain 
white bond paper, on one page only (copier bond is excellent). 
Do not underline or boldface and insert only one letter space 
between sentences. Provide a 1-inch margin top and bottom, 
a '/i-inch left margin, and an approximate '/6-inch ragged-right 
margin. Text may be submitted on diskette but must be 
accompanied by a hard copy. 

No identification of authors or institutions is to appear on 
the abstract sheet or in the abstract itself Make the abstract 
all one paragraph. Data may be submitted in table form provided 
the table width is limited to 60 letter spaces (ie, letters or 
numbers plus necessary blank spaces = 60). IMo figures or 
illustrations are to be attached to the abstract. 

Type all information required to complete the author 
information form on the other side of this page. A photocopy 
of good quality may be used. 

Standard abbreviations may be employed without explanation. 
A new or infrequently used abbreviation should be preceded 
by the spelled-out term the first time it is used. Any recurring 
phrase or expression may be abbreviated if it is first explained. 

Check the abstract for (1) errors in spelling, grammar, facts 
and figures; (2) clarity of language; (3) conformance to these 
specifications. An abstract not prepared as requested may not 
be reviewed. 

Questions about abstract preparation may be telephoned to 
the editorial staff of Respiratory Care at (214) 243-2272. 

Deadlines 

The mandatory Final Deadline is June 5 (postmark). Authors 
will be notified of acceptance or rejection by letter only — to 
be mailed by August 1 5. 

Authors may choose to submit abstracts early. Abstracts 
received by March 20 will be reviewed and the authors notified 
by April 26. Rejected abstracts will be accompanied by a written 
critique that should in many cases enable authors to revise their 
abstracts and resubmit them by the final deadline (June 5). 

Mailing Instructions 

Mail (Do not fax!) 1 copy of the abstract, 1 author information 
sheet, and a stamped, self-addressed postcard (for notice of receipt) 
to: 

Respiratory Care 
11030 Abies Lane 
Dallas TX 75229 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



235 



Please type: 



1991 OPEN FORUM 
AUTHOR INFORMATION SHEET 



Abstract title 



Principal author 



Institution 



Corresponding author 



Presenter 



Mail station, building, or room 



Mail station, building, or room 



Institution 



Institution 



Street address 



Street address 



City, State, Zip 



City, State, Zip 



Telephone 



Telephone 



Co-author 



Institution 



Co-author 



Institution 



Co-author 



Institution 



Mail, with abstract and stamped self-addressed postcard, to Respiratory Care Open Forum 
11030 Abies Lane, Dallas TX 75229 



RE/PIRATORy C^RE 



Instructions for Authors and Typists 



These Instructions are meant to guide authors and typists, including 
veterans in those roles, in the production of quahty manuscripts. Perfection 
is not expected, but the well-prepared manuscript has the best chance 
for prompt review and early publication. 

General Requirements 

Submissions should (1) be related to respiratory care, (2) be planned 
for one of the publication categories below, and (3) be prepared as 
indicated in these Instructions. A letter accompanying the manuscript 
must specify the intended publication category, be signed by all the authors, 
and, when there are two or more authors, state that "We, the undersigned, 
have all participated in the work reported, read the accompanying 
manuscript, and approved its submission for publication." 

Publication Categories 

Research Article (Study): A report of an original investigation. 

Evaluation of a Device/Method/Technique: A description and 

evaluation of an old or new device, method, technique, or modification. 

Case Report: A report of a clinical case that is uncommon or of 

exceptional teaching value. The author(s) must have been associated 

with the case. A case-managing physician must be one of the authors 

or, if not an author, must supply a letter approving the manuscript. 

Case Series: Like a Case Report but including a number of cases. 

Review Article: A comprehensive, critical review of the literature and 

state of the art of a pertinent topic that has been the subject of 40 

or more published research papers. 

Overview: A critical review of a pertinent topic about which not enough 

research has been published to merit a Review Article. 

Update: A report of subsequent developments in a topic that has been 

critically reviewed (not necessarily in this journal). 

Point of View: A paper expressing the author's personal opinions on 

a pertinent topic. 

Special Article: If a paper does not fit one of the foregoing categories 

but is pertinent, the editors may consider it as a Special Article. 

Editorial: A paper that draws attention to a pertinent concern. 

Letter: A signed communication about material published in this journal 

or on topics of interest or value to readers. 

Blood Gas Comer: A brief, instructive case report (real or fictional) 

involving invasively or noninvasively obtained respiratory care blood 

data, followed by questions for readers — with answers and discussion. 

PFT Comer: Like Blood Gas Corner but involving pulmonary function 

testing. 

Test Your Radiologic Skill: Like Blood Gas Comer and PFT Corner 

but involving pulmonary-medicine radiography and including one or 

two 4 X 5 or 5 X 7 inch prints of radiographs. The case must be real. 

Review of Book, Film, Tape, or Software: Anyone interested in writing 

a review can discuss it with an editor. 

Editorial Consultation and 
Author's & Typist's Kit 

To discuss a writing project, write to Respiratory Care, 1 1030 Abies 
Une, Dallas TX 75229 or call 214/243-2272. 

Authors are urged to obtain the Respiratory Care Author's & Typist's 
Kit. The Kit provides authors with specific guidance about writing a 
research paper, writing a case report, converting to and fi-om SI units. 



and in-house manuscript review. Typists can use the Kit's Model 
Manuscript, a list of journal name abbreviations, and a copy of these 
Instructions. The Kit is free from the Journal office. 

Preparing the Manuscript 
General Concerns — Typist 

• Double-space ALL lines, including those in references, figure legends, 
and tables. Do not justify right margins. 

• Number pages in upper right corner and leave margins of IVi" or 
more on all four sides of the page. 

• For research articles, follow format of Model Manuscript, Respir Care 
l984;29:182(Feb 1984). 

• Meticulously follow instructions for typing references. 

General Concerns — Author: 

• Structure manuscript as specified hereafter. 

• Provide all requested information on title page as specified hereafter. 

• Proofread manuscript for completeness, clarity, grammar, spelling; 
be sure all references, figures, and tables are cited in the text. 

• Consider having paper reviewed in-house before submission. 

• Have all co-authors proofread and approve manuscript and sign 
submission letter. 

Manuscript Stmcture 

Most kinds of papers have standard parts in a standard order. However, 
papers can vary individually, and not every paper will have all the parts 
listed here. 

Research Article: Title page, abstract page, continuous text (Introduction, 
Materials & Methods, Results, Discussion), Product Sources page. 
Acknowledgments page, references, tables, figure legends. Please consult 
"Writing a Research Paper," Respir Care I985;30:1057 (Dec 1985) 
and Model Manuscript, Respir Care 1984;29:182 (Feb 1984). 
Evaluation of Device/Method/Technique: Title page, abstract page, 
continuous text (Introduction, Description of Device/Method/Technique, 
Methods of Evaluation, Results of Evaluation, Discussion), Product 
Sources page. Acknowledgments page, references, tables, figure legends. 
Case Report or Case Series: Title page, abstract page, continuous text 
(Introduction, Case Summary, Discussion), Acknowledgments page, 
references, tables, figure legends. Also see "How To Write a Better Case 
Report," Respir Care 1982;27:29 (Jan 1982). 

Review Article: Title page. Table of Contents page, continuous text 
(Introduction, History, Review of Literature, State of the Art, Discussion, 
Summary), references. May include figures & tables. No abstract. Table 
of Contents optional. Other formats may be appropriate. 
Overview, Update, Point of View, or Special Article: Title page, text 
(introduction, message), references, tables, figure legends. No abstract. 
Letter: Title page (provide a title), text, writer's name & affiliation, 
references. Tables & figures may be included. Double-space everything. 
Write "For Publication" on title page. 

Structure: Important Details 

Title Page: List title of paper, all authors' full names, degrees, credential 
letters, professional positions, and affiliations. List correspondence address, 
telephone number, and reprint address if desired. Name sources of grants 
or other support. Identify any author's consulting or commercial 
relationships that pertain to the paper's topic. 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



237 



INSTRUCTIONS FOR AUTHORS & TYPISTS 



Abstract Page: Number this Page 1. List paper's title but omit authors' 
names. Abstract should be 200 words or less and must be informative, 
briefly specifying main points of paper, such as methods, results, and 
conclusions drawn. 

Statistical Analysis: In research articles, identify statistical tests and chosen 
level of significance in the Methods section. In Results section, report 
actual P values. 

Figures (illustrations): All photographs, diagrams, & graphs must be 
numbered as Figure 1, Figure 2, etc, according to the order in which 
each is first mentioned in the text. Photographs must be glossy prints 
5 X 7 to 8 X 10 inches and should be black & white unless color 
is essential. Letters and numerals must be neat and large enough to 
remain legible if figure is reduced in size for publication. Final figures 
must be of professional quality, but 'rough' sketches may accompany 
the submitted manuscript, with final figures to be prepared after review. 
Identify each figure on back with a stick-on label showing figure number 
and arrow indicating top: omit author's name. Cover label with clear 
tape so ink will not smudge other prints. Supply three sets of unmounted 
figures. If figure has been published before, include copyright-holder's 
written permission to use it. 

Figure Legends: List figure legends on a separate page, not on figures. 
If a figure has been published before, list the source in the fegend. 
Tables: Type each table on a separate page. Avoid more than 8 columns 
across. Continue a deep table on following pages. Give each table a 
number and descriptive title, placed above the table. Double-space ALL 
lines in tables, including column headings and footnotes. 
Drugs: Brand names may be given, but always also show generic names. 
Units of Measurement: In addition to conventional units of measure, 
show SI values and units in brackets after conventional expressions: ie, 
"PEEP, 10 cm H2O [0.981 kPa]." For conversion to SI, see Respiratory 
Care 1988;33:861-873 (Oct 1988). 

Commercial Products: If three or fewer commercial products are named 
in the text, list the manufacturer's name and location in parentheses 
the first time each is mentioned. If four or more products are named, 
do not list manufacturers in the text; instead, name the products and 
manufacturers in a Products Sources list at the end of the text. Provide 
model numbers when available. 

Abbreviations: Use an abbreviation 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. Do not create 
new abbreviations unless absolutely necessary. 

References: 

• Use references to support statements of fact, indicate sources of 
information, or guide readers to further pertinent literature. 

• Cite only published works — or works accepted for publication. When 
listing an accepted but still unpublished work, designate the accepting 
journal's name, followed by "(in press)." 

• In the text, cite references by superscript numerals (half space above 
text), not in parentheses. The first reference cited in the text is number 
I, the next is number 2, etc. 

• In the reference list, place the cited works in numerical order. 

• For the reference list, obtain author names, article and book titles, 
dates, volume and page numbers from the original cited articles and 
books, not from secondary sources such as other articles' reference lists, 
which often are inaccurate. 

• Type references in medical-journal style. Examples appear at the end 
of these Instructions. Abbreviate journal names as in Index Medicus. 
A list of many journal-name abbreviations was published in Respir Care 
I988;33;1050(Nov 1988). 

• DOUBLE-SPACE the lines of references. 

• List ALL authors' names. Do not use "et al" to substitute for names. 

• Identify abstracts, editorials, and letters as such. See examples. 
Personal Communications, Unpublished Papers, and Unpublished 
Observations: List unpublished items in parentheses in the text, not 
in the reference list. 



Examples of How To Type References 

Notes: Although the examples here are printed with single-spaced lines, 
please double-space references in manuscripts. Also, note that words 
in article and book titles are not capitalized — except proper names. 

Standard Journal Article: 

1. Shepherd KE, Johnson DC. Bronchodilator testing: An analysis of 
paradoxical responses. Respir Care 1 988;33:667-67 1 . 

Corporate Author Journal Article: 

2. American Association for Respiratory Care. Criteria for establishing 
units for chronic ventilator-dependent patients in hospitals. Respir 
Care 1988;33:1044-1046. 

Article in Journal Supplement: 

(Journals differ in their methods of numbering and identifying 

supplements. Supply sufficient information to allow retrieval.) 

3. Reynolds HY. Idiopathic interstitial pulmonary fibrosis. Chest 
I986;89(3, suppl):139s-143s. 

Abstract in Journal: 

(Abstracts are not strong references; when possible, full papers should 

be cited. When cited, abstracts should be identified as such.) 

4. Lippard DL, Myers TF, Kahn SE. Accuracy of pulse oximetry in 
severely hypoxic infants (abstract). Respir Care 1988;33:886. 

Editorial in Journal: 

5. Rochester DF. Does respiratory muscle rest relieve fatigue or incipent 
fatigue? (editorial). Am Rev Respir Dis 1988;138:516-517. 

Letter in Journal: 

6. Smith DE, Herd D, Gazzard BG. Reversible bronchoconstriction 
with nebulised pentamidine (letter). Lancet 1988;2:905. 

Personal Author Book: 

7. Nunn JF. Applied respiratory physiology. New York: Appleton- 
Century-Crofts, 1969. 

Note: To specify pages cited in a book, place a colon after the year 
and then list the page(s). Examples: 1969:85 (one page), 1963:85-95 
(series of contiguous pages), 1963:85,95 (separated pages). 
Corporate Author Book: 

8. American Medical Association Department of Drugs. AMA drug 
evaluations, 3rd ed. Littleton CO: Publishing Sciences Group, 1977. 

Book with Editor, Compiler, or Chairman as 'Author': 

9. Guenter CA, Welch MH, eds. Pulmonary medicine. Philadelphia: 
JB Lippincott, 1977. 

Chapter in Book: 

10. Pierce AK. Acute respiratory failure. In; Guenter CA, Welch MH, 

eds. Pulmonary medicine. Philadelphia: JB Lippincott, 1977:171- 

223. 

Submitting the Manuscript 

After preparing the manuscript according to these Instructions, perform 
a final proofreading and check for accuracy and completeness. Then 
mail three copies of the manuscript and three sets of figures to 
Respiratory Care, 1 1030 Abies Lane, Dallas TX 75229 (or Federal 
Express to Respiratory Care, 11030 Abies Lane, Dallas TX 75229). 
Manuscript copy on IBM-compatible or Macintosh disks in addition 
to the requisite three hard copies will facilitate processing (Macintosh 
preferred). Enclose a letter as specified under General Requirements 
at the beginning of these Instructions. Do not submit material that has 
been published or is being considered elsewhere. 

Author's Checklist 

1 . Is paper for a listed publication category? 

2. Does cover letter meet specifications? 

3. Is title page complete? 

4. Are all pages double-spaced and numbered? 

5. Are all references, figures, and tables cited in the text? 

6. Are references typed in requested style? 

7. Have SI values been provided? 

8. Has all arithmetic been checked? 

9. Has manuscript been proofread by all authors? 



238 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 




start your own 

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"IJ/c und Iheuth "can start you on your 
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It explains the roles of respiratory care 
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senior citizens, to students, to staff and 
other hospital professionals. 



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Tel: (416) 926-7098 Fax: (416) 926-4988 




THt WELLEsi.t;\ Hospital 



239 



Authors 

in This Issue 



Abraham, Edward 231 

Barnes, Thomas A 161 

Daly, Barbara 199 

Gilmartin, Mary E 205 

Goldstein, Roger S 184 

Hanowell, Leland 173 

Hess, Dean 232 

Kacmarek, Robert M 232 

Lain, David C 222 

Lawrence, Gretchen 229 

Martin, Walter R 173 

Mathewson, Hugh S 218 

Mishoe, Shelley C 222 

Montenegro, Hugo D 199 



Morey, Curt M 222 

Nochomovitz, Michael L 199 

Parran, Susan 199 

Pierson, David J 184 

Shigeoka, John W 178 

Soriano, Sulpicio 173 

Stockwell, Deborah L 161 

Stoller, James K 186 

Taft, Arthur A 222 

Thorarinsson, Bjorn 222 

Thurston, David 173 

Wright, John 231 

Yoshihara, Gary 231 



Advertisers 
in This Issue 



Bird Products Corp 158 

Ciba-Corning Diagnostics 154, 155 

DHD Medical 160 

Hamilton Medical 220 

HealthScan Products 217 

ICN Pharmaceuticals Inc 224a 

Lifecare 1 56 

Medical Graphics Corp 228 

Employment Opportunities 

The Wellesley Hospital, Toronto, Canada 239 



Monaghan Medical Corp 226, 227 

Newport Medical Instruments 151 

Puritan-Bennett Corp Cover 2, 145 

Quinton Instrument Co 146 

Respironics Inc 230 

Schering-Plough Cover 3, Cover 4 

Sherwood Medical 152 

Siemens Life Support Systems 148 



240 



RESPIRATORY CARE • MARCH '91 Vol 36 No 3 



81 AARC 

Membership Info 

82 RESPIRATORY CARE 
Subscription Info 

100 Bird Products Corp 
VIP Bird Ventilator 

102 Ciba-Corning Diagnostics 

CLIA Compliance 
112 DHD Medical 

Incentive Spirometers 
160 Hamilton Medical Inc 

Veolar Ventilator 
115 HealthScan Products 

Assess Peak Flow Meter 
122 ICN Pharmaceuticals Inc 

Virazole 

126 Lifecare 
Portable Ventilator 

127 Medical Graphics Corp 
Corporate 

142 Monaghan Medical Corp 
AeroVent 

101 Newport Medical 
Neonatal /Pediatric Ventilator 

152 Puritan-Bennett Corp 
5-Yr Warranty 7200ae 

140 Puritan-Bennett Corp 
Reusable Tubing System 

105 Quinton Instrument Co 
PFT System 

141 Respironics Inc 

BagEasy Manual Resuscitator 
114 Schenng-Plough 

Proventil Solution 
131 Sherwood Medical 

PF/Ventilation Monitor 
124 Siemens Life Support Systems 

Servo Ventilator 



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Pluu Cird* No Mora Than IS N«nt 






12 3 4 


S 


6 7 8 9 10 11 12 13 14 15 


16 


17 18 19 20 


21 22 23 24 


25 


26 27 28 29 30 31 32 33 34 35 


36 


37 38 39 40 


41 42 43 44 


45 


46 47 48 49 50 51 52 S3 54 55 


56 


57 58 59 60 


61 62 63 64 


65 


66 67 68 69 70 71 72 73 74 75 


76 


77 78 79 80 


81 82 83 S4 


85 


86 87 888990 9192939495 


96 


97 98 99 100 


101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 


121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 


141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 



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6 7 8 9 10 11 12 13 14 15 


16 


17 18 19 20 


21 


22 23 24 «25 


26 27 28 29 30 31 32 33 34 35 


36 


37 38 39 40 


41 


42 43 44 45 


46 47 48 49 50 51 52 53 54 55 


56 


57 58 59 60 


61 


62 63 64 65 


66 67 68 69 70 71 72 73 74 75 


76 


77 78 79 80 


81 


82 83 84 85 


86 87 88 89 90 91 92 93 94 95 


96 


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101 


102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 


121 


122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 


141 


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L Type si InMR/Prscttcv 

1. a Hosp- 500 or more beds 

2. a Hosp 300 to 500 beds 
a O Hosp- 200 to 300 beds 

4. a Hosp. 1 00 to 200 beds 

5. a Hosp. 100 or tess beds 

6. O Clintc/Group Practice 

7. D lr)depef>deni RT Provider 

8. D iTKfustry (Ibtfgr/ Sales) 



A. D neepiratory Ther. 

B. O Cardiopulmonary 

C. O Anesthesia Service 

D. D Emerger>cy Dept. 



1. D CHrtical Practice 

2. O Perinatal Pediatrics 

3. D Critical Care 

4. D Clinical Research 

5. D Pubrnmary Func Lab 
& O Home Care/Rehab 

7. D Education 

8. D Ii4anagemenl 

IV. PBiMon 
A.O0aptHead 
a O Chief Therapist 
CD Supervisor 

D. O Staff Technician 

E. D Staff Therapist 

F. D Educator 

a D Medical Director 
K D Anesthesiologist 
I. D Other MD 
J. D Nurse 



V. ArefDua 

1, DYes 

2. DNo 



QfttieAARC? 



L Type o( luabi/ Practice 

1. a Hosp. 500 or more beds 

2. a Hosp 300 to 500 beds 
a a Hosp 200 Ic 300 beds 

4. D Hosp. 100 to 200 beds 

5. O Hosp- 100 or less beds 

6. O Clinic/Qroup Practice 

7. a Indeperxlent RT Provider 

8. a Industry (Mfgr/Sales) 

N. Dapertnant 

A. a naapiratory Ther. 

B.D Cardiopulmortary 

C. n Anealhesia Service 

D. D Emeroency Depi 



1. G Clinical Practice 
2 D Perinatal Pediatrics 

3. G Critical Care 

4. G Oinical Research 

5. G Pulmorwry Func Lab 

6. G HofTte Care/ Rehab 

7. G Education 

8. G Mar»gement 



A.GOept Head 
a G Chief Therapist 
C. G Supervisor 

0. G Staff Technician 
e. G Staff Therapist 

F. G Educator 

G. G Medical Director 
H. D Anesthesiologist 

1. DOtfterMD 
J. DMurse 

V. Are you a member of the AARC? 

1. GYes 

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THE 0/VIKAPPROVED 
ALBUTEROL SULFATE UNIT DOSE 



IT'S THE EASY SOLUTION 



Proventil 

(albuterol sulfate) 

Solution for Inhalotion 



Unit Dose 0.083%* 
0.5%' 20 mL bottle 

'Potency expressed as albuterol 



Please see full prescribing 
information on adjacent page 



Copyright ©1991, Schering Corporation 

All rights reserved 

PN-073/1 6898406 2/91 Printed in U.S.A. 



Schering Corporation 
Kenilworth, NJ 07033 




IT'S THE EASY SOLUTION 



Proventil 

(albuterol sulfate) 
Solution for Inhalation 



Unit Dose 0.083%* 
0.57o* 20 mL bottle 

'Potency expressed as albuterol 



DESCRIPTION PROVENTIL, brand ol aibulerol sulfate, Solution lor Inhala- 
tion, is a relalively selective belaj-adienergic bronchodilalot (see CLINICAL 
PHARMACOLOGY section belo*) Albuterol sulfate has the chemical name 
o'-|(/ert-Bulylamino) methyl|-4-hydroxy-m-xylene-a.o'-diol sulfate (2:1) 
(salt), and the following chemical structure: 






> — ' rv 



HCHjNHCiCHj), 

OH 



Albuterol sullate has a molecular weight of 576 7 and the empirical formula 
(C,3H2iN03)2*H2S04, Albuterol suHate is a white crystalline powder, soluble in 
water and slightly soluble in ethanol. 

The international generic name tor aibulerol base is salbutamol 

PROVENTIL Solution lor Inhalation is available in two concentrations. The 
05% solution is in concentrated torm Dilute 5 mL of the solution to 3 mL 
with normal saline solution prior to administration. The 0,083% solution re- 
quires no dilution prior to administration. 

Each ml of PROVENTIL Solution lor Inhalation (0 5%) contains 5 mg of 
albuterol (as 6.0 mg of albuterol sulfate) in an aqueous solution containing 
benzalkonium chloride; sulfuric acid is used to adjust the pH between 3 and 5. 
PROVENTIL Solution for Inhalation (0,5%) contains no sulfiting agents. It is 
supplied in 20 mL bottles. 

Each mL of PROVENTIL Solution tor Inhalation (0.083%) contains 0,83 mg 
of albuterol (as 1.0 mg ol albuterol sulfate) in an isotonic aqueous solution 
containing sodium chloride and benzalkonium chloride; sulfuric acid is used to 
adjust Ihe pH between 3 and 5, PROVENTIL Solution for Inhalation (0.083%) 
contains no sulfiting agents. II is supplied m 3 mL bottles for unit-dose 
dispensinp 

PROWJTIL Solution for Inhalation is a clear, colorless to light yellow 
solution. 

CLINICAL PHARMACOLOGY The prime action of beta-adrenergic drugs is 
to stimulate adenyl cyclase, the enzyme which catalyzes the formation of 
cyclic-3',5'-adenosine monophosphate (cyclic AMP) from adenosine triphos- 
phate (ATP). The cyclic AMP thus formed mediates the cellular responses. In 
vitro studies and in vivo pharmacologic studies have demonstrated that albuterol 
has a preferential effect on beta-adrenergic receptors compared with isoprotere- 
nol. While it is recognized that beta2-adrenergic receptors are the predominant 
receptors in bronchial smooth muscle, recent data indicate that 10 to 50% of Ihe 
beta receptors in the human heart may be beta2 receptors. The precise function 
of these receptors, however, is not yet established Albuterol has been shown in 
most controlled clinical trials to have more eflect on the respiratory tract, in the 
form of bronchial smooth muscle relaxation, than isoproterenol at comparable 
doses while producing fewer cardiovascular effects. Controlled clinical studies 
and other clinical experience have shown that inhaled albuterol, like other beta- 
adrenergic agonist drugs, can produce a significant cardiovascular effect in 
some patients, as measured by pulse rate, blood pressure, symptoms, and/or 
EGG changes. 

Albuterol is longer acting than isoproterenol in most patients by any route of 
administration because it is not a substrate for Ihe cellular uptake processes for 
catecholamines nor for catechol-0-methyl transferase 

Studies in asthmatic patients have shown that less than 20% of a single 
albuterol dose was absorbed following either IPPB or nebulizer administration; 
the remaining amount was recovered from the nebulizer and apparatus and 
expired air Most of the absorbed dose was recovered in the urine 24 hours after 
drug administration Following a 3 mg dose of nebulized albuterol, the max- 
imum albuterol plasma level at 0.5 hour was 21 ng/mL (range 1.4 to 3.2 
ng/ml). There was a significant dose-related response in FEV, and peak flow 
rate (PFR). II has been demonstrated that following oral administration of 4 mg 
albuterol, the elimination hall-lile was 5 to 6 hours 

Animal studies show that albuterol does not pass the blood-brain barrier 
Recent studies in laboratory animals (minipigs, rodents, and dogs) recorded the 
occurrence of cardiac arrhythmias and sudden death (with histologic evidence of 
myocardial necrosis) wtien beta-agonists and methylxanthines were admin- 



istered concurrently. The significance of these findings when applied to humans 
is currently unknown. 

In controlled clinical trials, most patients exhibited an onset ol improvement 
in pulmonary tunction within 5 minutes as detemiined by FEV,. FEV, measure- 
ments also showed that the maximum average improvement in pulmonary 
function usually oaurred at approximately 1 hour following inhalation of 2 5 mg 
of albuterol by compressor -nebulizer, and remained close to peak lor 2 hours. 
Clinically significani improvement in pulmonary function (defined as mainte- 
nance of a 15% or more increase in FEV, over taseline values) continued for 3 
to 4 hours in most patients and in some patients continued up to 6 hours 

In repetitive dose studies, continued effectiveness was demonstrated 
throughout the 3-month period of treatment in some patients, 

INDICATIONS AND USAGE PROVENTIL Solution for Inhalation is indicated 

for the relief of bronchospasm in patients with reversible obstructive airway 
disease and acute attacks of bronchospasm. 

CONTRAINDICATIONS PROVENTIL Solution for Inhalation is contraindi- 
cated in patients with a history of hypersensitivity to any of its components, 

WARNINGS As with other inhaled beta-adrenergic agonists, PROVENTIL 
Solution for Inhalation can produce paradoxical bronchospasm, which can be 
life threatening. If il occurs, the preparation should be discontinued immediately 
and alternative therapy instituted. 

Fatalities have been reported in association with excessive use of inhaled 
sympathomimetic drugs and with the home use of sympathomimetic nebulizers. 
It is. therefore, essential that Ihe physician instruct the patient in the need tor 
further evaluation il his/her asthma becomes worse. In individual patients, any 
beta2-adrenergic agonist, including albuterol solution for inhalation, may have a 
clinically significani cardiac effect. 

Immediate hypersensitivity reactions may oaur alter administration ol al- 
buterol as demonstrated by rare cases of urticaria, angioedema, rash, bron- 
chospasm, and oropharyngeal edema. 

PRECAUTIONS General: Albuterol, as with all sympathomimetic amines, 
should be used with caulion in patients with cardiovascular disorders, especially 
coronary insufficiency, cardiac arrhythmias and hypertension, in patients with 
convulsive disorders, hyperthyroidism or diabetes mellitus, and in patients who 
are unusually responsive to sympathomimetic amines. 

Large doses of intravenous albuterol have been reported to aggravate preex- 
isting diabetes mellitus and ketoacidosis. Additionally beta-agonists, including 
albuterol, when given intravenously may cause a decrease in serum potassium, 
possibly through intracellular shunting. The decrease is usually transient, not 
requiring supplementation. The relevance of these observations to the use of 
PROVENTIL Solution for Inhalation is unknown. 

Inlormation For Pallents: The action of PROVENTIL Solution lor Inhala- 
tion may last up to 6 hours and therefore it should not be used more frequently 
than recommended. Do not increase the dose or Irequency of medication without 
medical consultation, II symptoms get worse, medical consultation should be 
sought promptly. While taking PROVENTIL Solution for Inhalation, other anti- 
asthma medicines should not be used unless prescribed 

Drug Interactions: Other sympathomimetic aerosol bronchodilators or epi- 
nephrine should not be used concomitanlly with albuterol. 

Albuterol should be administered with extreme caution to patients being 
treated with monoamine oxidase inhibitors or tricyclic antidepressants, since the 
action ol albuterol on the vascular system may be potentiated. 

Beta-receptor blocking agents and aibulerol inhibit the effect of each other. 

Carcinogenesis, Mutagenesis, and impairment of Fertility: Al- 
buterol sulfate, like other agents in its class, caused a significant dose-related 
increase in the incidence of benign leiomyomas ol the mesovarium in a 2-year 
study in the rat, at oral doses corresponding to 10, 50, and 250 times the 
maximum human nebulizer dose. In another study, this effect was blocked by the 
coadministration of propranolol The relevance ol these findings to humans is 
not known An 18-month study in mice and a lifetime study in hamsters revealed 
no evidence ol tumorigenicity. Studies with albuterol revealed no evidence of 
mutagenesis. Reproduction studies in rats revealed no evidence ol impaired 
fertility 

Teratogenic Ettects-Pregnancy Category C: Albuterol has been shown 
to be teratogenic in mice when given subcutaneously in doses corresponding to 
the human nebulization dose. There are no adequate and well -control led studies 
in pregnant women. Albuterol should be used during pregnancy only il the 
potential benefit justifies the potential risk to the fetus, A reproduction study in 
CD-I mice with albuterol (0025, 0,25, and 2,5 mg/kg subcutaneously, corre- 
sponding to 0.1, 1, and 12 5 times the maximum human nebulization dose, 
respectively) showed dell palate formation in 5 ol 111 (4 5%) ol fetuses at 025 
mg/kg and in 10 ol 108 (9.3%) of fetuses at 2,5 mg/kg. None were observed at 
0,()25 mg/kg. Cleft palate also occurred in 22 ol 72 (30,5%) of fetuses treated 
with 2,5 mg/kg isoproterenol (positive control). A reproduction study in Stride 
Dutch rabbits revealed cranioschisis in 7 ol 19 (37%) ol fetuses at 50 mg/kg, 
corresponding to 250 times the maximum human nebulization dose. 

Labor and Delivery: Oral albuterol has been shown to delay preterm labor 
in some reports. There are presently no well-controlled studies which demon- 
strate that it will stop preterm labor or prevent labor at term Therefore, cautious 
use of PROVENTIL Solution for Inhalation is required in pregnant patients when 
given tor reliel of bronchospasm so as to avoid interference with uterine 
contractibility 

Nursing Mothers: It is not known whether this drug is excreted in human 
milk. Because of the potential for tumorigenicity shown for albuterol in some 
animal studies, a decision should be made whether to discontinue nursing or to 

Circle 114 on reader service card 



discontinue the drug, taking into account the importance of Ihe drug to the 
mother. 

Pediatric Use: Safety and effectiveness of albuterol solution for inhalation 
in children below the age of 12 years have not been established. 
ADVERSE REACTIONS The results of clinical trials with PROVENTIL Solu- 
tion for Inhalation in 135 patients showed the following side effects which were 
considered probably or possibly drug related: 

Central Nervous System: tremors (20%), dizziness (7%), nervousness (4%). 
headache (3%), insomnia (1%). 
Gastrointestinal: nausea (4%), dyspepsia (1%). 
Ear Nose and Throat: pharyngitis (<1%), nasal congestion (1%). 
Cardiovascular: tachycardia (1%), hypertension (1%), 
Respiratory: bronchospasm (8%), cough (4%), bronchitis (4%), wheezing (1%). 

No clinically relevant laboratory abnormalities related to PROVENTIL Solu- 
tion for Inhalation administration were determined in these studies. 

In comparing the adverse reactions reported lor patients treated with 
PROVENTIL Solution for Inhalation with those of patients treated with isoproter- 
enol during clinical trials ol 3 months, Ihe following moderate to severe reac- 
tions, as judged by the investigators, were reported. This table does not include 
mild reactions. 

Percent Incidence of Moderate To Severe Adverse Reacti o n s 



Reaction 


fm 


ISSpr^^ 


Central Nervous System 

Tremors 

Headache 

insomnia 


107% 
3.1% 
3.1% 


13,8% 
1.5% 
1.5% 


Cardiovascular 

Hypenension 
Arrhythmias 
"Palpitation 


3.1% 
0% 
0% 


31% 
3.0% 
22.0% 


Respiratory 

"Bronchospasm 

Cough 

Bronchitis 

Wheeze 

Sputum Increase 

Dyspnea 


154% 
3.1% 
1.5% 
1.5% 
1.5% 
1.5% 


18% 
5% 
5% 
1,5% 
1.5% 
1.5% 


Gastrointestinal 

Nausea 
Dyspepsia 


31% 
1.5% 






Systemic 

Malaise 


15% 






'In most cases of bronchospasm, this term was generally used to descritje exacerfea- 

tions in Ihe underlying pulmonary disease 
"The linding ol no arrhythmias and no palpitations alter aibulerol administration in 

this clinir:al study should not he interpreted as indicating that these adverse eflecis 

cannot occur alter the administration ol inhaled albuterol 

Rare cases ol urticaria, angioedema, rash, bronchospasm. and 
oropharyngeal edema have been reported alter the use ol inhaled albuterol 
OVERDOSAGE Manitestations ol overdosage may include anginal pain, hy- 
pertension, hypokalemia, and exaggeration ol the pharmacological etiecis listed 
in AOVERSE REACTIONS. 

The oral LDu, in rats and rrice was greater than 2,000 mg/kg. The inhala- 
tional LD^ could not be determined 

There is insullicieni evidence to determine if dialysis is beneficial for over- 
dosage ol PROVENTIL Solution lor Inhalation 

DOSAGE AND ADMINISTRATION The usual dosage lor adults and chif- 
dren 12 years and older is 2 5 mg ol aibulerol administered 3 to 4 times daily by 
nebulization More frequent administration or higher doses is not recommended. 
To administer 2 5 mg ol albuterol, either dilute 5 mL ol Ihe 5% solution lot 
inhalation to a total volume ol 3 mL with normal saline solution, or adminisler 
the contents ol one unit-dose boftfe (3 mL of 083% nebufizer solution) by 
nebulization. The tfow rate is regulaled to suil the particular nebulizer so Ihal Ihe 
PROVENTIL Solution tot Inhalation will be delivered over approximately 5 lo 15 
minutes 

The use ol PROVENTIL Solution tor Inhalalion can be continued as medicafly 
indicated to control recurring bouts ol bronchospasm During treatment, most 
patients gain optimum benefil from regular use of the nebulizer solution 

It a previously effective dosage regimen faifs lo provide the usual reliet 
medical advice should be sought immediately, as this is olten a sign ol seriously 
worsening asthma which would require reassessment ol therapy 
HOW SUPPLIED PROVENTIL Solution for Inhalation, 0.5%, is a clear, color- 
less to light yellow solution, and is supplied in bofffes ol 20 mL 
(NDC-0085-0208-02) with accompanying calibrated dropper: boxes of one. 
Store between 2° and 25°C (36° and 77°F). 

PROVENTIL Solution for Inhalation, 0.083%, is a clear, colorless to light 
yellow solution, and is supplied in unit-dose bottles ol 3 mL each, boxes of 25 
(NDC-0085-0209-01 ) Store between 2° and 25°C (36" and 77°F). 



Schering Corporation 
Revised 1/90 Kemlworlh, NJ 07033 USA 13934339 

CopytlgW e 1986. 1987, 1990, Sdnring Corporation, kenllwonli. (U 07033 All rigWs reseivM