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JULY 2002
VOLUME 47
NUMBER 7

ISSN 0020-1324-RECACP

A MONTHLY SCIENCE JOURNAL
47TH YEAR— ESTABLISHED 1956

EDITORIALS

SPECIAL ISSUE

AIRWAY CLEARANCE
TECHNIQUES

Secretion Clearance Techniques

SYMPOSIUM PAPERS

Physiology of Airway Mucus Clearance

Positioning vs Postural Drainage

Autogenic Drainage and Active Cycle of
Breathing

Positive Pressure Techniques

High-Frequency Oscillation of the Airway and
Chest Wall

Techniques for Artificial Airways

Mucoactive Agents

Strategies for the Pediatric Patient

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We've all heard horror stories about patients who were denied access to care by their MCOs.
Sometimes, it's hard to separate fact from fiction. As a former medical reviewer for one of the
nation's largest insurers, Dr Linda Peeno has the inside track and will share it with conven-
tioneers during the opening ceremonies. The subject of a recent movie on Showtime called
"Damaged Care," she has dedicated her life to exposing what she calls "the menace of man-
aged care."

Come hear what Dr. Peeno has to say about the financial incentives driving medical coverage
today and what we ought to be doing to create a more equitable system for all.

As the "gold standard" of respiratory care meetings worldwide, the AARC Congress provides
you with everything you need to know to stay abreast of important developments in the respira-
tory care profession. It's your number one convention destination for:

• The lowest cost of continuing education per credit!

• The largest and most impressive Exhibit Hall, featuring the most vendors AND the ability to
buy right onsite.

• The largest gathering of respiratory experts in the world.

• The most diverse and dynamic series of lectures.

• The largest presentation of original research by RTs.

• The most opportunities for YOU to network with your peers.

Don't miss this opportunity to attend the
longest-running respiratory therapy show in history!

October 5-8, 2002 • Tampa Bay, Florida
48th Annual International Respiratory Congress

For more information, visit www.aarc.org

and click on Tampa Bay. Or call 972-243-2272.

American Association for Respiratory Care

11030 Abies Lane, Dallas, TX 75229

Vrato*""

Visit www.visittampabay.com for up-to-date information about things to see and do in Tampa Bay.

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JULY 2002 / VOLUME 47 / NUMBER 7

FOR INFORMATION,
CONTACT:

AARC Membership
or Other AARC Services

American Association for

Respiratory Care

11030 Abies Ln

Dallas TX 75229-4593

(972) 243-2272 • Fax (972) 484-2720

tittp://www.aarc.org

Therapist Registration or
Technician Certification

National Board tor Respiratory

Care

8310Nieman Rd

LenexaKS 66214

(91 3) 599-4200 • Fax (91 3) 541 -01 56

http://www,nbrc,org

Accreditation of Education
Programs

Committee on Accreditation for

Respiratory Care

1701 W Euless Blvd. Suite 300

Euless TX 76040

(817) 283-2835 • Fax (817) 354-8519

tittpV/www, coarc.com

Grants. Scholarships.
Community Projects

American Respiratory Care

Foundation

11030 Abies Ln

Dallas TX 75229-4593

(972) 243-2272 • Fax (972) 484-2720

AARC Government Affairs Office

Director of Govt Affairs

Jill Eicher

1225 King St, Second Floor

Alexandria VA 22314

(703) 548-8538 Fax (703) 548-8499

eicher@aarc.org

Director of State Govt Affairs
Cheryl West MHA
8630 Braeswood Pt. #2
Colorado Springs. CO 80920
(719) 535-9970 west@aarc, org

RE/PIRATORy
Q\RE

RtSIMK\r<)R\ CVRE (ISSN 0020-1324. USPS 0489-
190) IS published monthl> by Daedalus Enierprises Inc, al
1 1030 Abies Lane. Dallas TX 75229-4593. for (he .\mer-
ican Association tor Respiraiorv Carc- One volume is
published per year beginning each January Subscription
rates are S75 per year in the US; SMO in all other countries
(for airmail, add $94)

The contents oC the Jounial are indexed in liuhw
A/fJ/(i(.\7MEDLINE. Hospital and Health Administralion
Index. Cumulative Index to Nursing and Allied Health
Literature. EMBASE/Excerpla Medica. and RNdex Li*
brary Edition. An abridged version ot RhSPlR.ATORV
Care is also published in Japanese, with permission from
Daedalus Enterpnses Inc.

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

©^rinled on acid-free paper.

Printed in the Uniitii Siutcs of Amvrua

17TH ANNUAL

NEW HORIZONS SYMPOSIUM:

AIRWAY CLEARANCE TECHNIQUES

GUEST EDITORS

James B Fink MSc RRT FAARC
^ Bruce K Rubin MEngr MD FAARC

EDITORIALS

Secretion Clearance Techniques: Absence of Proof e^r Proof o\' Absence?

h\ Di'iiu R Hew — Bosion. Md.ssachu.selfs

757

FOREWORD

New Horizons in Respiratory Care; Airway Clearance Techniques

hy James B Fink — Mounlain View. California

and Bruce K Rubin — Winston-Salem. North Carolina

759

SYMPOSIUM PAPERS

Physiology of Airway Mucus Clearance

h\ Bruce K Rubin — Winston-Salem, North Carolina

Positioning Versus Postural Drainage

by James B Fink — Mountain View. California

Airway Physiology. Autogenic Drainage, and Active Cycle of Breathing

by Craig D Lapin — Hartford, Connecticut

Positive Pressure Techniques for Airway Clearance

by James B Fink — Mounlain Vien: California

High-Frequency Oscillation of the Airway and Chest Wall

by Jtunes B Fink — Mountain View. California

and Michael J Mahlmeister — San Mateo. California

Airway Clearance Techniques for the Patient with an Artificial Airway

by Robert M Lewis — Atlanta. Geori^ia

The Pharmacologic Approach to Airway Clearance: Mucoactive Agents

by Bruce K Rubin — Winston-Salem. North Carolina

Airway Clearance Strategies for the Pediatric Patient

by Kalhryn L Davidson — Salt Lake City. Utah

761
769
778
786

797
808
818
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CONTINUED.

ALSO
IN THIS ISSUE

AARC Membership
839 Application

746

Abstracts from
Other Journals

848

Advertisers Index
& Help Lines

848

Author
Index

847

Calendar
of Events

841

Manuscript
Preparation Guide

845

Hevi Products

846

Notices

BOOKS, FILMS, TAPES, & SOFTWARE

PlissiothLMapy in Rcspiraldiy Care: An lividencc-Bascd Approach
to Respiratory and Cardiac Management. 3rd ed (Hough A)

rcr/ciiri/ h\- Dennis C Siihiixh -Milwaukee. Wi\eonsin

Mosby's Complementary & Alternative Medicine: A Research-Based
Approach (Freeman LW, Lawlis GF)

reviewed h\ Jim BlairSeatlle. Wu.shin^fiin

Pharmacology in Respiratory Care (Levine SR, McLaughlin AJ Jr)

reviewed In Hni;lt S Malhewson — Kansas City. Kansas
Carbon Monoxide Toxicity (Penney DG, editor)

reviewed I'v Liiulell K Weaver—Sail Lake City. Utah

Respiratory Care Sciences: An Integrated Approach. 3rd ed
(Wojciechowski WV)

reviewed h\ Conrad Colhy— Boise. Idaho

Pediatric Pulnionology Pearls (Inselman LS)
reviewed bv Michelle M Cloiitier— Hartford. Connecticut

Teaching in Your Office: A Guide to Instructing Medical Students
and Residents (Alguire PC, DeWitt DE. Pinsky LE. Ferenchick GS)

reviewed In Mark G Graham — Philadelphia. Pennsylvania

AARC'S INTERNATIONAL
RESPIRATORY CONGRESS

OCTOBER 5-8, 2002

829

829
830
831

833
833

834

RE/PIRATORy
CARE

A Monthly Science Journal
Established in 1956

The Official Journal of the

American Association for

Respiratory Care

This year's International Respiratory

Congress in Tampa, Florida, promises

to offer many unique cultural, educational,

and other entertaining experiences to

its attendees. Come to Tampa for one

of the most breathtaking educational

events of the year. Be sure to mark

your 2002 calendar for the next AARC

Congress, October 5-8, 2002.

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EDITORIAL OFFICE

()()0 Ninth A\emn.'. Siiilc 702

Seattle \V A yS 104

(20(i)22.V0.'i?8

Fax (206) 223-0563

www.rcjournal.com

MANAGING EDITOR

R;i\ Maslerrer RRT FAARC

EDITOR IN CHIEF

David J Pierson MD FAARC

//i//7'(iM icn Miiliciil Criihr
i'iii\ci:sil\ of \Va\luiif;li)ii
SfcinU'. Wdsllilliildll

ASSOCIATE EDITORS

Richard D Branson RRT FAARC
[ 'niversity- of Cincmmtti
Ciminnuti. Ohio

Dean R Hess PhD RRT FAARC

Masstulmsetts General ihispiuil
Harvard University
Boston. MasMichusetls

James K Sioller MD MSc FAARC
The Cleveland Clinu foundalinn
Cleveland. Ohio

ASSISTANT
EDITOR

Kathenne Kreilkanip

EDITORIAL
ASSISTANT

LinJa Baivus

COPY EDITOR

Matthew Mero MA

PRODUCTION

Kelly Piotrowski

MARKETING

Dale L Gnttlihs
Director of Market m^

Tim Goldsbury RRT
Director. Advertising Sales

Beth Binkley

Advertising Assistant

PUBLISHER

.Sam P Giordano MBA
RRT FAARC

RE/PIRATORy
QVRE

A Monthly Science Journal
Established in 1956

The Official Journal of the

American Association for

Respiratory Care

Charle^ G Durhin Jr MD FAARC
L'nivi-r\it\ ct Vu\;inta
ChitrlolU'Svillt'. \ 'iii;inui

EDITORIAL BOARD

Neil R Maclntyre MD FAARC
DtiU Uiiivt'r\lt\
Diithiim. NtuJh Caroiiiui

Alexander B Adains MPH RRT
FAARC

Rcf^ionx HospiUll
Si Paid. Minnesnui

Thomas A Barnes EdD RRT
FAARC

Niirllicaslfm Vniwrsity
Boston. Maisachiisciis

Joshua O Benditt MD

Uiincisily ofWaslliiiK'o'i
Seattle. Wa.'^hiiislon

Michael J Bishop MD

University of Wasliiiif;i<in
Seattle. Washinf;ion

LIuis L Blanch MD PhD
Hospital lie Sahailell
Stihailell. Siuiiti

Bartolome R Celli MD
Tufts University
Boston. Massaelmsetts

Robert L Chatburn RRT
FAARC

University Hospitals of Clevehnul
Case We.slern Re.ser^e Universit\
Cleveland. Ohio

Patrick J Dunne MEd RRT
FAARC

Health Care Produetions
Fullerton. California

James B Fink MS RRT FAARC

.■\eroCien hie

Mountain View. California

John E Heffner MD

Medual University of South Carolina
Charleston. Simlh Carolina

Mark J Heuiitt MD FAARC

L 'niversity of A rkansas
Little Rock. Arkansas

SECTION EDITORS

Leonard D Hudson MD

University of Washini>tiin
Seattle. Wasliini;lon

Robert M Kacmaiek PhD RRT
FAARC

Massachiisetls Oeneial Hospital
Harvard Universitv
Boston. Massaehiisetis

Richard H Kallet MS RRT

San Franciseo General Hospital
Univer.iity of Califinnta San Franciseo
San Francisco, California

E Lucy Kester MBA RRT
FAARC

The Cleveland Clime Foundation
Cleveland. Ohio

Max Kirmse MD

University of Eriangen-Niirnherg
Mohrendorf. Germany

Toshihiko Koga MD FAARC
Koga Instituet fen- Medical Research
Tokyo. Japan

Marin H Kollef MD

Washington University
St Louis. Missouri

Constantine A Manthous MD
Bridgeport Hospital
Bridgeport. Cfmiiectictd

John J Murini MD

Universitv of Miimesola
St Paul. Minnesota

Shelley C Mishoe PhD RRT
FAARC

Medical College of Georgia
Augusta. Georgia

Steven B Nelson MSc RRT

FAARC

Overland Paik. Kansas

Ma\o Pulmonary Sen-ices

Rochester. Mmnesola

Marcy F Petri ni PhD

Ullivcrsilx of Mississippi
.lackson. Mississippi

Joseph L Rau PhD RRT FAARC

Georgia State University
.Atlanta, Georgia

Catherine SH Sassoon MD

University of California Inine
Ijmg Beach. California

John W Shigeoka MD

Veterans Administration Medical Center

Salt hike Cit\. Utah

Eric J Stern MD
Hai-boniew Medical Center
( Iniversity of Washington
Seattle. Washington

Martin J Tobin MD

Loxola Universitx
Chicago. Illinois

Jeffrey J Ward MEd
RRT FAARC

.Mayo Medical School
Rochester. Minnesota

Robert L Wilkins PhD RRT
FAARC

hima Linda I 'nivcruty
Lama Linda. California

STATISTICAL CONSULTANT

Gordon D Rubcnfeld MD MSc

University of Washington
Seattle. Washinglim

Hughs MalhcwMin MD
Joseph L Rau PhD RRT [AARC
Drug Capsule

Charlc G In in PhD

C}reg2 L Ruppcl Mhd RRT RPPT lAARC

PFT Corner

Richard D BranMin RRT FAARC
Roben S Campbell RRT FAARC
Kittredgc's Corner

Sicven B Nelson MSt
RRT FAARC
RC Web Sites

Jon NiKcsiuen PhD RRT FAARC
Ken Hargetl RRT
Graphics Comer

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

Abstracts

Summaries of Pertinent Articles in Other Journals

Editorials, Commentaries, and Reviews to Note

Can Health Care Costs Be Reduced l)> IJniiting Intensive Care at the Knd of Life? — luce
JM, RulxTilckKM) All) J Rcpir Crit Care Med 2(10: Mar ]5;I6.S(6|:75()-7S4.

Future Research Directions in Chronic Obstructive Pulmonary Disease — Croxton TL. Wein-
inann GG, Senior RM, HoiJal JR Am J RespirCril Care Med 2002 Mar 15:165(6):838-844.

Clinical Practice. Acute Exacerbations of Chronic Obstructive Pulmonary Disease — Stoller

JK. N i-.ngi J Med 2002 Mar 28;346( 1 3):9SX-994.

Should Family Members Be Present During Cardiopulmonary Resuscitation? — Tsai E. N
Engl J Med 2002 Mar 28;346( LM; 10! 4- 1 02 1 .

Air Pollution and Short Term Mortality (ediluriall — Hennessy E. BMJ 2002 Mar
23;324(7339l:691-692.

Saving Face: Better Interfaces for Noninvasive Ventilation — Hill S Intensive Care Med 2002
Mar;28( 3 1:227-229.

Evidence-Based Medicine or Fuzzy Logic: What Is Best for ARDS Management? — Dreyfuss
D. Saumon G. Intensive Care Med 2002 Mar;28(3):230-234.

F'videncc-Based Medicine in the Therapy of the Acute Respiratory Distress Syndrome —

K(ipp R, Kuhlen R. Max M. Rossaint R. Intensive Care Med 2002 Mar;28(3):244-255.

Lung Abscess in Adults: Clinical Comparison of Immunocompro-
mised to Non-Immunocompromised Patients — Mansharaniani N. Bal-
achandran D. Delaney D. Zibrak JD, Silvestri RC. Koziel H. Respir Med
2002 Mar;9f>(3):178-18.'i.

Information related to the clinical characteristics and isolated microbes
associated with lung abscesses comparing immunocompromised (IC) to
non-immunocompromised (non-IC) patients is limited. A retrospective
review for 1984-1996 identified 34 consecutive adult cases of lung
abscess (representing 0.2'7f of all cases of pneumonia), including 10 non-
IC and 24 IC patients. Comparison of age. gender, tobacco use, pre-exist-
ing pulmonary disease or recognized aspiration risk factors were not sig-
nificantly different between the two groups. Upper lobe involvement
accounted for the majority of cases, although multi-iobe involvement was
limited to IC patients. There were no differences in the need for surgical
intervention, and mortality was very low for both groups. Anaerobes
were the most frequent isolates for non-IC patients (30%), whereas aer-
obes were the most frequent isolate for IC patients (63%). Importantly,
certain organisms were exclusively isolated in the IC group and multiple
isolates were obtained only from the IC patients.Thus. comparing non-IC
to IC patients, clinical characteristics may be similar whereas important
differences may exist in the microbiology associated with lung abscess.
These findings have important implications for the clinical management
of these patient groups, and support a strategy to aggressively identify
microbial agents in abscess material.

Inipacl of a Family Information I.eatlet on FTfectiveness of Informa-
tion Provided to Family Members of Intensive Care Unit Patients: A
Multicentcr, Prospective, Randonii/,cd, Controlird Trial — A/oulay E,
Pochard H, Chevret .S. Jourdain M, Bornslain C, Wernet A, el al. Am J
RespirCnt Care Med 2002 Feb 15;lh.'S(4l:438-442.

Comprehension and satisfaction are relevant criteria for evaluating the
effectiveness of information provided to family members of intensive
care unit (ICU) patients. We performed a prospective randomized trial in
34 French ICUs to compare comprehension of diagnosis, prognosis, treat-
ment, and satisfaction with information provided by ICU caregivers, in
ICU patient family representatives who did (n = 871 or did not (n = 88)
receive a family information leaflet (FID in addition to standard informa-
lion. An FIL designed specifically for this study was delivered at the first
visit of the family representative: it pro\ ided general information on the
ICU and hospital, the name of the ICU physician caring for the patient, a
diagram of a typical ICU room with the names of all the devices, and a
glossary of 12 terms commonly used in ICUs. Characteristics of the
ICUs, patients, and family representatives were similar in the two groups.
The FIL reduced the proportion of family members with poor compre-
hension from 40.9% to 1 1.5% (p < 0.0001). In the representatives with
good comprehension, the FIL was associated with significantly better sat-
isfaction (21 [ 1 8 to 24, quartilesj versus 27 |24 to 29, qu;u-tiles], p = 0.01 ).
These results indicate that ICU caregivers should consider using an FIL
to improve the effectiveness of the information lhe\ impart to families.

Incidence and Mortality of .Acute Lung Injury and the .\cutc Respi-
ratory Distress Syndrome in Three .Australian States — Bersten AD,
Edibam C, Hunt T, Moran J, Group TA. Am J Respir Crit Care Med 2002

Feb l5;16.'>(4):443-448.

To determine the incidence and 28-d mortality rale for acute lung injury
(.ALl) and acute respiratory distress syndrome (ARDS) using the 1994
American-European Consensus Conference definitions, ue prospectively
screened every admission to all 2 1 adult intensive care units in the States
of South Australia. Western Australia, and Tasmania (total population
older than I. 'i yr of age estimated as 2,941,137), betvveen October 1 and
November 30. 1999. A total of 1,977 admissions were screened of which

746

Respirators Care . Juls 2002 Vol 47 No 7

SETTING the STANDARD /or AIRWAY CLEARANCE.

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The Vest™ system consists of an inflatable vest connected by tubes to an air-pulse generator. The
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More than 3,000 physicians have prescribed The Vest system for 20,000 patients with respiratory
complications associated with more than 280 diseases and conditions.

The Vest system sets the standard for airway clearance therapy:

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Abstracts

IfiS developed Al.l and I4S developed ARDS. v\hich represents a first
incidence of 34 and 28 cases per l(M).0()0 per annum, respectively. The
respective 28-d mortality rates were i29c and .34%. The most common
predisposing factors for ALI were nonpulmonary sepsis (319'r) and pneu-
monia {2^'7r). Although the incidences of AI.I and ARD.S are higher and
the mortality rates are lower than those reported from studies in other
countries, multicenter international studies are required to exclude
methodological differences as the cause for this finding.

Improved .Arterial Oxygenation with Biologically \ ariable or Frac-
tal \ entihition I'sing Low Tidal \'oliime.s in a Porcine Model of .Acute
Respiratory Distress Syndrome — Boker A. Ruth Ciraham M. Wallcy
KR. McManus BM, Girling LG, Walker E, et al. Am J Respir Crit Care
Med 2002 Feh l-'i;l6.'S(4l:4.';6-462.

We compared biologically variable ventilation (Vhv; n = 9) with control
mode venlilalion (V^; n = 8) at low tidal volume ( VtI — initial 6 mL/kg —
in a porcine model of acute respiratory distress syndrome (ARDS).
Hemodynamics, respiratory gases, airway pressures, and Vx data were
measured. Static P-V curves were generated at .") h. Inlerleukin (lL)-8 and
IL-10 were measured in serum and tracheal aspirate. By .^ h. higher PaO;
(173 ± 30 mm Hg versus 1 19 ± 23 mm Hg; mean ± SD: p < 0.0001 group
xtime interaction |G x T]), lower shunt fraction (6 ± 1% versus 9 ±3%; p
= 0.0026. G X T) at lower peak airway pressure (2 1 ± 2 versus 24 ± 1 cm
H:0; p = 0.0342; G x T) occurred with Vbi- IL-8 concentrations in tra-
cheal aspirate and wet:dry weight ratios were inversely related: p = 0.01 1 .
With V^, IL-8 concentrations were 3.75-fold greater at wet:dry weight
ratio of 10. IL-10 concentrations did not differ between groups. In both
groups, ventilation was on the linear portion of the P-V curve. With Vbv.
Vt variability demonstrated an inverse power law indicating fractal
behavior. In this model of ARDS, Vbv improved PaO; at lower peak air-
way pressure and IL-8 levels compared with V^.

Kffect of Lung Volume Reduction Surgery for Severe Emphysema on
Right \ entricular Function — Mineo TC. Pompeo E. Rogliani P. Dauri
M. Turani F. Bollero P, Magliocchetti N. .Am J Respir Crit Care Med
2002 Feb I.5;I65(4):489-4'M.

Lung volume reduction surgery (LVRS) can improve the functional
capacity of selected patients with severe emphysema. Hypothesized
physiologic effects of LVRS include an improvement in right ventricular
function, although this has not been investigated in detail. To help clarify
this issue, we used fast-thermistor thermodilulion at rest and during sub-
ma.ximal upright exercise in 12 patients, before and 6 mo after bilateral
LVRS. Preoperative^, all patients had severe airflow obstruction, with a
mean FEV, of 0.69 L and an RV-to-TLC ratio of 0.67. Six months after
LVRS. significant improvements occurred in respiratory function mea-
sures (-1-0.39 L in FEV,. p < 0.002; and -0. 15 in RV/TLC ratio, p < 0.002)
and in right ventricular function indexes measured at rest (■(■0.21 L in car-
diac index |CI|, p < 0.01; and +i.O mL in stroke volume, p < 0.01) and
during exercise (■hO.9 L in CI, p < 0.002; ■•■10.0 niL in stroke volume
index, p < 0.002; and -(-20'/f in ejection fraction |EF], p < 0.002). A sig^
nificant correlation was found between pre^ to postoperative changes in
the EF response to exercise and changes in the RV/TLC ratio (R = -0.68;
p = (1.01 ). We conclude thai a significant improvement in right ventricular
performance, particularly during exercise, can occur 6 mo after bilaleral
LVR.S.

Pulmonary Function. Body Composition, and Protein Catabolism in
Adults «ilh Cystic Fibrosis- loiicscii .A.A. Nixon l,S, Lu/io S. Lewls-
Jenkins V. Evans WD. Slonc MD. ct al. Am J Respn Crit Care Med 2002
Feb l5;l65l4l:495-.5()().

Increased survival in cystic fibrosis (CF) is associated with bone thin-
ning and fat-free mass (FFM) loss. We hypothesized that the se\erity of

lung disease would be associated with increased protein catabolism and
systemic inflammatory status in clinically stable patients. Forty adults
with CF and 22 age-matched healthy subjects were studied. Body com-
position was determined by dual-energy X-ray absorptiometry. Urinary
pseudouridine (PSU). a marker of protein breakdown, and cross-linked
N-telopeptides of type I collagen (NTx), a marker of bone connective
tissue breakdown, serum tumor necrosis factor (TNF)-a, interleukin
(lLl-6, and their soluble receptors were measured. A 3-d food intake
diary revealed 21 patients had a low energy intake. Excretion of PSU (p
= 0.019) and NTx (p < 0.01 ) was increased in patients and was inversely
related to FEV,; PSU (r = - 0.53, p = 0.001 ) and NTx (r = - 0.43. p <
0.01 ). Increased excretion of PSU and NTx (p < 0.05 for both) was also
related to a low FFM. All inflammatory mediators were greater in
patients and were related to PSU and NTx. Clinically stable adults were
catabolic with both cellular and connective tissue protein breakdown,
which was related to lung disease severity, systemic inflammation, and
body composition.

Screening for Lung Cancer » ith Low -Dose Spiral Computed Tomog-
raphy— Swensen SJ. Jett JR. Sloan JA, Midthun DE, Hartman TE. Sykes
AM, et al. Am J Respir Crit Care Med 2002 Feb I5;165(4);508-513.

Studies suggest that screening with spiral computed tomography can
detect lung cancers at a smaller size and earlier stage than chest radiogra-
phy can. To evaluate low -radiation-dose spiral computed tomography
and sputum cytology in screening for lung cancer, we enrolled 1.520 indi-
\ idnals aged 50 >r or older who had smoked 20 pack-years or more in a
prospective cohort study. One year after baseline scanning, 2,244 uncal-
cified lung nodules were identified in 1,000 participants (66%). Twenty-
five cases of lung cancer were diagnosed (22 prevalence. 3 incidence).
Computed tomography alone detected 23 cases; sputum cytology alone
delected 2 cases. Cell types were: squamous cell. 6: adenocarcinoma or
bronchioalveolar. 15: large cell, I; small cell. 3. Twenty-two patients
underwent curative surgical resection. Seven benign nodules were
resected. The mean size of the non-small cell cancers detected by com-
puted tomography was 17 mm (median. 13 mm). The postsurgical stage
was lA. 13: IB. 1: IIA. 5: IIB. 1: IIIA. 2: limited. 3. Twelve (57%) of the
21 non-small cell cancers detected by computed tomography were stage
lA at diagnosis. Computed tomography can detect early-stage lung can-
cers. The rate of benign nodule detection is high.

Nosocomial Infections in a Neonatal Intensive Care Unit: Incidence
and Risk Factors — Nagata E, Brito AS, Matsuo T. .Am J Infect Control
2002 Feb:.3()(l):26-3I.

BACKGROUND: Nosocomial infections (NIs) have become a matter of
major concern in neonatal intensive care units (NICUs). The objectives of
this study were to determine the incidence rate and the most frequent sites
of infection in a Brazilian NICU from January 1 999 to March 2000 and to
study the risk factors for NIs. METHODS: A cohort study w as carried out
in which 225 neonates who remained at least 24 hours in the NICU were
followed-up; neonates with NIs were identified, and the presence of risk
factors was studied. Results were submitted to X" distribution.
RESULTS: The incidence rate and the incidence density rate were 50.7%
and 62 infections per 1000 patient-days, respectively. In order of fre-
quency, the sites of infection were: pneumonia (40.3%), primary blood-
stream (16.7%). skin and .soft tissue (14.9% ). and meningitis (9.6% ). The
following risk factors were associated with NIs (p <0.05): birth weight,
gestational age. mechanical ventilation, total parenteral nutrition, umbili-
cal catheter, use of antibiotics, and intubation in the delivery room. CON-
CLUSION: Risk factors were similar to those reported by other authors.
However, incidence rales of infections in our NICU were much higher,
possibly because of different methodologies and the adopted criteria for
the classification of NIs.

748

RESPIRATOR') Care . July 2002 Vol 47 No 7

Abstracts

Surveillance of Ventilator-Associated I'lU'iinionia in \it)-I,o«-
Birth-WeiKhl Infants— Cunicri) L, Avers I.W. Milkr RR. Segiiin III
Coley Hn Am J Intecl Control 2(X)2 Feb;3()( 1 );3:-39.

BACKGROUND: Surveillance of ventilator-associateJ piieunioni.i
(VAP) is an essential part of quality patient care. Very-low-birth-weighi
(VI.BW) infants, many with tracheal microbial colonization and bron-
chopulmonary dysplasia (BPDl. comprise a difficult group in whom to
make a diagnosis of pneumonia with the Centers for Disease Control anil
Prevention (CDCl criteria tor inlants younger than I year. OBJbCTIVI
Our objective was to retrospectively compare VAP surveillance diag-
noses made by the hospital infection control practitioner (ICP) with those
made by a panel of experts with the same clinical and laboratory evidence
and supportive radiologic data. A secondary objective was to compare
radiologic diagnosis of pneumonia made by the general hospital radiolo-
gists, by the panel of experts, and by a pediatric radiologist from another
hospital. Study Population: Thirty-seven VLBW infants identified as at
nsk for VAP by the ICP on the basis of a positive bacterial tracheal cul-
ture and the application of CDC criteria for the definition of pneumonia
were studied. METHODS: Clinical and laboratory evidence and routine
radiologic reports made by the general radiologist were reviewed inde-
pendently by a panel of experts composed of .^ experienced neonatolo-
gists. Chest x-rays from the day before, day of. and day after the surveil-
lance date were reviewed separately by the 3 neonatologists and also by a
pediatric radiologist. RESULTS: After inter-reader reliability was found
satisfactory (kappa's coefficient, 0.47-0.75; p <0.05), the panel of neona-
tologists determined that the 37 VLBW infants represented 4 distinct
clinical categories. Group 1 comprised 12 airway-colonized infants, aged
14 to 30 days, who on the surveillance date, albeit intubated, were asymp-
tomatic, not treated with antibiotics, and survived. Group 2 comprised 1 1
ainv ay -colonized infants, aged 7 to 42 days, who presented with equivo-
cal clinical, laboratory, or radiologic signs of VAP and survived. Group 3
comprised 7 airway-colonized infants, aged 14 to 21 days, who were
acutely ill (3 died) and had clinical and laboratory evidence of nosoco-
mial bloodstream infection (BSI) but no radiologic signs of pneumonia.
Group 4 comprised 7 infants, aged 14 to 28 days, who were acutely 111 (4
died) and had clinical and laboratory evidence of infection and radiologic
changes consistent with VAP. Radiologic Findings: General radiologists,
neonatologists, and the pediatric radiologist agreed that none of the
asymptomatic airway-colonized infants (Group I) had VAP. General
radiologists reported signs suggestive of pneumonia in 8 of 1 1 infants
(Group 2), a finding not corroborated by the others. Everybody agreed on
the absence of radiologic pneumonia in 6 of 7 patients with nosocomial
BSI (Group 3) and on the presence of signs consistent with pneumonia in
the remaining 7 infants (Group 4). CONCLLISION: Surveillance diagno-
sis of VAP in VLBW infants is ditTicult because current CDC definitions
are not specific for this population. Isolated positive tracheal culture
alone does not distinguish between bacterial colonization and respiratory
infection. Clinical and laboratory signs of VAP, mostly nonspecific, can
be found in other conditions such as bronchopulmonary dysplasia and
nosocomial BSI. Routine radiologic reports suggestive of pneumonia in
airway-colonized infants without definitive clinical and laboratory evi-
dence of infection could be misleading. To improve accuracy, surveil-
lance diagnosis of VAP in special populations such as VLBW infants
should be reformulated; meanwhile. ICPs should seek consultation with
experienced clinicians for interpretation of data.

The risk of Hospitalization and Near-Fatal and Fatal Asthma in
Relation to the Perception of Dyspnea — Magadle R. Berar-Yanay N.
Weiner P. Chest 2002 Feb;121(2):329-333.

BACKGROUND: A life-threatening asthma attack is still of major con-
cern. One of the main goals in treating patients with asthma is identifica-
tion of the patients at nsk of having these attacks. It has been shown that
patients who have a near-fatal asthma attack have a blunted perception of

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dyspnea (POD). The purpose of this study is to measure the POD in
patients with asthma, and to relate POD to life-threatening attacks within
a 24-month follow-up period. METHODS: The POD was scored using
the Borg scale during breathing against a progressive load at 1-min inter-
vals, in order to achieve mouth pressure up to W cm HjO, in 1 13 consec-
utive asthmatic patients with stable asthma attending an outpatient clinic.
All patients were invited to regular follow-up every 3 months for up to 24
months, and all hospitalizations and near-fatal and fatal asthma attacks
were recorded. The prebronchodilator morning peak expiratory flow rate
(PEFR), daily regular treatment, and Bi-agonist consumption were
recorded in a diary card for the first 4 weeks. RESULTS: Seventeen
patients (15%) had high POD compared to the nomial subjects. 67
patients 1599}-) had POD within the normal range, and 29 patients (269!-)
had lower-than-normal POD. In the patients with low POD. there was a
tendency for higher age, higher female/male ratio, and a longer duration
of disease. The rate of severe asthma was higher in the low -POD group
than in the normal-POD group, but did not differ from the rale in the
high-POD group. The mean daily 6:-agonist consumption in the patients
with low POD was significantly lower (p < 0.01 ) than in the patients with
high POD, although the mean PEFR was lower in the low-POD group.
During the 2 years of follow-up. the patients in the low-POD group had
statistically significantly more emergency department {EDi visits, hospi-
talizations, near-fatal asthma attacks, and deaths compared to the normal-
POD and high-POD groups. CONCLUSIONS: Appro.vimately 26'/ of
the referral subjects v. Ith asthma had low POD when compared to healthy
matched subjects. Patients with low POD had statisticallv significantlv
more ED visits, hospitalizations, near-fatal asthma attacks, and deaths

RESPIRATORY CaRE • JULY 2002 VOL 47 NO 7

749

Abstracts

during the lolldu-iip pcnnd. Rccliii.cd POD [iiay pivtlLsp^sc palicnls to a
life-lhrealening allack. See the accompanyiiifi editorial: Pink puffers vs
blue hloaleis in iislhma hhk' Alilrich TK. Cliesi 2002 Feh.l2l(2):313-3I5.

Oropharyngeal l)i'!>liititi(iii in Stable COPI) — Mokhlcsi B, Logemann
JA. RadL-MKikcr AW. Slarigl CA, Curbridge TC. CheM 2002
Feb;121(2);361-36y.

STUD^i' OBJLC TIVES; The aim of this siudy was lo L-xamim: deglutition in
stable patients with COPI) and lung hyperinllation. DHSIUN; Twenty eon-
secutlve. eligible COPD patients with an FEV| < 65'/c of prcdieted and a
total lung eapaeily > 120% of predicted were enrolled prospectively.
INTERVENTION: Patients received a detailed videofluoroscopic evalua-
tion of oropharyngeal swallowing and were compared to 20 age-matched
and sex-matched historical control subjects. SETTING: An outpatient pul-
monale clinic at a Veterans Affairs Medical Center. MEA.SUREMENTS
AND RH.SUI.TS: The mean total king capacity, functional residual capac-
ity, and residual volume for the patients were 128'/?^ of predicted, 1689!^ of
predicted, and 2 1 8'/r of predicted, respectively. The mean FEV i was 39'^ of
predicted. There was no evidence of tracheal aspiration in either group. The
laryngeal position at rest measured relative to the cervical vertebrae was not
different between groups. The maximal laryngeal elevation during swallow-
ing was significantly lower in patients with COPD (p < O.OOI ). Patients with
COPD exhibited more frequent use ot spontaneous protective swallowing
maneuvers such as longer duration of airway closure and earlier laryngeal
closure relative to the cricopharyngeal opening than did control subjects (p <
O.D.'S). CONCLUSIONS: We conclude that hypermllatcd patients with
COPD have an altered swallowing physiology. We suspect that the protec-
tive alterations in swallowing physiology (swallow maneuvers) may reduce
the risk of aspiration. However, these swallowing maneuvers may not be
useful during an exacerbation and may require further research.

Body Mass Index and the Risk of COPD— Hank Khan Rl, Fleg JL,
Wise RA. Chest 2002 Feb:121(2):37()-376.

BACKGROflND: Previous studies have documented the prognostic value
of low body weight in patients w ith COPD and also in general populations.
However, it is not clear whether low body weight is a risk factor for COPD
or a consequence of established disease. STUDY OBJECTIVE; To deter-
mine whether asymptomatic subjects with low initial body mass were at a
greater risk of having COPD develop during subsequent follow-up.
DESIGN AND SUBJECTS: Observational retrospective study of 4.'S8 male
and 192 female participants (age range, 40 to 7.3 years) in the Baltimore
Longitudinal Study of Aging. .At baseline, the participants did not have
COPD. After tnean follow-up periods of 10.2 years for the men and 6.4
years for the women, 40 men and 7 women received a diagnosis of COPD.
METHODS: Cox proportional-hazards regression models were used to
assess the relationship between COPD diagnosis and baseline body mass
index (BMI) in men. RESULTS: The risk of COPD developing in men var-
ied inversely with baseline BMI, even after adjusting for other risk factors,
including cigarette smoking, age, FEV| percent predicted, abdominal obe-
.sity, and educational status. In men, the relative risk of COPD developing
for the lowest BMI tcrtile relative to the highest tcrtile was 2.7fi {95'i con-
fidence interval, \.\5 to b.59). The small number of women who had
COPD did not allow us to draw conclusions regarding BMI as a risk factor
for COPD. CONCLUSION: After controlling for confounding variables,
men with low BMI are at increased risk for getting COPD.

Disconlinuullon of Fiiroseniidv Decreases Paio in Patients with
COP!) -Bnikci f. Hei|dia Yf, \an den l-Jshout FJ, l-olgenng HT. Chest
2002 Feb;121(2):.^77-3S2.

STUDY OBJECTIVE: To evaluate whether the discontinuation of
furosemide treatment resulted in a decrease in P.ico.. and an increase in day-
hnie and nociurn:il owgenation. BACKGROUND: Furosemide is widelv

prescribed in patients with COPD for the treatment ol peripheral edema. It is
known that furosemide cau.ses a metabolic alkalosis. A diminished chemore-
ceptor stimulation may cause a decreased alveolar ventilation. DESIGN:
Randomized, double-blind, placebo-controlled, crossover trial. SETTING:
Department of Pulmonology, Rijnstate Hospital Arnhem. the Netherlands.
PATIENTS: Twenty patients with stable COPD (10 men; median age, 70
years (range, ."iS to 81 years]; FEV| 3,'S'/f predicted jrange, 19 to 70';i pre-
dicted! 1. Subjects were included if they had received lurosemide, 40 nig/d,
for the treatment ot peripheral edema for at least a month and if they had a
mean nocturnal anerial oxygen saturation (Sjo?) < 92'/r. Patients with ciir-
diac left and/or right ventricular dysfunction, sleep apneas, and patients
receiving other diuretics, angiotensin-converting en/.yme inhibitors, potas-
sium or chloride replacement therapy, or long-term oxygen treatment were
excluded. INTERVENTION: Furosemide was discontinued for 1 week and
replaced by placebo treatment in the first or the second week. MEASL'RE-
MENTS AND RESULTS: Ventilation, daytime arterial blood gas levels,
and nocturnal Sjo. were measured at baseline, alter I. and after 2 weeks.
Sixteen subjects completed the study. Ventilation increased from 10.4 IVmin
(range. 6.7 to 1.^.4 L/niin) at baseline to 11.6 L/min (range. 8.7 to 14.0
L/min) after discontinuation of furosemide (p<O.O.S). Pjco; decreased from
45 mm Hg (range, 35 to 64 mm Hg) to 41 mm Hg (range, 32 to 61 mm Hg:
p < 0.01 ). Daytime and nocturnal oxygenation did not improve. CONCLU-
SIONS: Although it does not improve oxygenation, the discontinuation of
furosemide decreases PjCO; in patients with COPD.

KfTects of Acetazolamide and Furosemide on Ventilation and Cere-
bral Blood Volume in Normocapnic and Hypercapnic Patients with
COPD— van de Ven MJ. Colier WN, van der Sluijs MC. Oeseburg B.
Vis P. Folgering H. Chest 2002 Feb:121(2):383-.392.

STUDY OBJECTIVES: Effects of chronic metabolic alkalosis and acido-
sis and their relation to central chemoregulation may differ between nor-
mocapnic and chronic hypercapnic patients \vith COPD. The relationship
between responses of inspired ventilation ( V|). mouth occlusion pressure
(Po.i). and cerebral blood volume (CBV). to short-term changes in anerial
Pco: was measured. PATIENTS AND METHODS: Seventeen patients
with chronic hypercapnia and COPD ( Pjco; > 6.0 kPa) and 16 normocap-
nic patients with COPD (P;,co: ^ 60 kPa) |FEVi 27% predicted] were
studied under baseline metabolic conditions and after 1 week of treatment
with oral furosemide. 40 mg/d. or acetazolamide. 500 mg/d. Hypercapnia
(change in end-tidal carbon dioxide > 1 kPa) was induced by administer-
ing adequate amounts of carbon dioxide in the inspired air. CBV was
measured using near-infrared spectroscopy. RESULTS: Compared with
baseline metabolic condition, chronic metabolic acidosis and alkalosis
did not change ventilatory (AV|/AP.|CO:) and cerebrovascular
(ACBV/APaco;) reactivity. Base excess (BE) decreased by 6.8 ± I.I
mEq/L and 6.9 ± 1.6 niEq/L. respectively, in the normocapnic and
chronic hypercapnic COPD groups during metabolic acidosis, resulting
in a not-quite-significant leftward shift of both the ventilatory and cere-
brovascular carbon dioxide response curve. BE increased by 2.3 ± 1.2
mEq/L and 1.2+ 1.3 mEq/L. respectively, during chronic metabolic alka-
losis in both COPD groups, without concomitant shift. Poor correlations
between ventilatory and cerebrovascular carbon dioxide responsiveness
(ACBV/AR,a>; and AV,/AP.,ro:. ACBV/AP,co; and AP„ |/AP.,a)... respec-
tively) were found irrespective of baseline, respiratory condition, and
induced metabolic state. CONCLUSIONS: Normocapnic and chronic
hypercapnic COPD patients have the same ventilatory and cerebrovascu-
lar carbon dioxide responsiveness irrespective of induced metabolic state.

Impact of Body Weight on Long-Term .Sur>i>al After Lung Trans-
plantation— Kanasky WF Jr. Anton SD. Rodrigiie JR. Pern MG. Szwed
T. Ba/ MA. Chest 2002 Feb;121(2):4()l-406.

STUDY OBJECTIVES: The purpose of this study was to detenmne the
impact ol a pietranspl.ml.ilion determination of body mass index iBMll

750

Respiratory Care . July 2002 Vol 47 No 7

on survival atier lung iransplantatlnn. DESIGN AND PATIENTS: Uni-
variate and multivariate sur\ival analyses of a single insiitutiim database
consisting of X5 patients who had undergone lung transplanlalions
between March I W4 and October 1948. SETTING; University ol Florida
Health Science Center. RESULTS: Kaplan-Meier survival curves
showed that patients who were obese (ie. BMl. > 30) at a pretransplania-
tion assessment had a marked decrease in posttransplantation survival
time (log rank, p < 0.05; Wilcoxon, p < 0.05). The final Cox regression
model revealed that the most powerful predictors of monality after lung
transplantation were higher pretransplantation BMl and the development
of obliterative bronchiolitis. CONCLUSIONS: Our results suggest that
the posttransplantation risk for mortality is possibly three times greater
for obese patients than for nonobese patients. Additional study is needed
to identify the mechanisms for such higher risk in obese patients. Our
data also suggest that transplantation centers should not routinely reject
underweight patients (ie. BML < 18.5) or overweight patients (ie. BML
25 to 29.9) for lung transplantation listing solely on the basis of weight,
as their outcomes may not be significantly different than patients with
normal BMIs.

Determinants of Chronic Hypercapnia in Japanese Men with
Obstructive Sleep Apnea Syndrome — Akashiba T. Kawahara S.
Kosaka N. Ito D. Saito O. Majima T. Horie T. Chest 2002

Feb:i:i(2):4l5-42l.

STUDY OBJECTIVE: To identify the determinants of chronic hypercap-
nia (ie. Paco:. S 45 mm Hg) in men with obstructive sleep apnea syn-
drome (OSAS) without airflow ob.struction. DESIGN: An analysis was
conducted of 143 male patients with OSAS, which had been diagnosed by
polysomnography (PSGi. who had been referred to a university hospital.
Patients were classified as hypercapnic (ie. Paco:. - '♦S mm Hgl and nor-
mocapnic (ie. Pjco;. < 45 mm Hgl. and obese (ie. body mass index
|BMI], > 30 kg/m-) or nonobese (ie. BML < 30 kg/m-). Patients with air-
flow obstruction (ie. FEVi/FVC ratio. < 70%) were excluded from the
study. Baseline clinical characteristics, pulmonary function. PSG data,
and blood gas data were compared between hypercapnic and normocap-
nic patients. Correlations between PaCO; and several anthropometric, res-
piratory, and polysomnographic variables were determined by stepwise
multiple regression analysis. RESULTS: Fifty-five patients (38%) were
hypercapnic. Hypercapnic patients were younger and heavier, and had
more abnormalities on pulmonary and PSG testing. Stepwise multiple
regression analysis revealed that the Paco: ie\e\ was influenced signifi-
cantly by the mean level of arterial oxygen saturation (SaO;) during sleep
and by the percent of vital capacity (% VC) (R- = 0.430; p < 0.0001 ). indi-
cating that 43% of the total variance in the PaCO; could be explained by
the mean SaO; and %VC in hypercapnic patients. In contrast, only 13% of
the total vanance in the Paco; was accounted for by the mean SaO; and
BMl in normocapnic patients (R- = 0.134; p = 0.0034). The mean SaO;.
%VC. and PaO: were selected as independent variables for predicting the
PaCO' '" obese patients. These variables explained 41% of the total vari-
ance in the Paco; (R" = 0.407; p < 0.0001 ). whereas the mean SaO; only
accounted for 13% of the total variance in Paco: levels in nonobese
patients (R= = 0.134; p = 0.00641. CONCLUSION: Nocturnal desatura-
tion and restrictive pulmonary impairment play major roles in determin-
ing the PaCO; in hypercapnic and obese OSAS patients without airflow
obstruction.

Severe Obstructive Sleep Apnea Is Associated with Left Ventricular
Diastolic Dysfunction — Fung JW. Li TS. Choy DK. Yip GW. Ko FW.
Sanderson JE. Hui DS. Chest 2002 Feb;I21(2):422-429.

INTRODUCTION: Hypertension is common in patients with obstructive
sleep apnea (OSA). However, the effect of OSA on ventricular function,
especially diastolic function, is not clear. Therefore, we have assessed the
prevalence of diastolic dysfunction in patients with OSA and the relation-

Respiratory Care . July 2002 Vol 47 No 7

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Abstracts

ship between diastolic parameters and severity of OSA. MBTHODS:
Sixty-eight consecutive patients with OSA confirmed by polysomnogra-
phy underwent echocardiography. Diastolic function of the left ventricle
was determined by trunsmitral valve pulse-wave Doppler echocardiogra-
phy. Various ba.seline characteristics, severity of OSA, and echocardio-
graphic parameters were compared between patients with and without
diastolic dysfunction. RESULTS: There were 61 male and 7 female
patients with a mean age of 48. 1 ± II . I years, body mass inde.\ of 28.5 ±
4.3 kg/m-, and apnea/hypopnea index (AHI) of 44.3 ± 23.2/h (mean ±
SD). An abnormal relaxation pattern (ARP) in diastole was noted in 25
patient.s (36.8%). Older age (52.7 ± 8.y years vs 45.1 ± 1 1.3 years, p =
0.0051, hypertension (56% vs 20%, p = 0,002). and a lower minimum
pulse oximetric saturation (SpoO during sleep (70.5 ±' 17.9% vs 78.8 ±
12.9%, respectively; p = 0.049) were more common in patients with
ARP. By multivariate analysis, minimum Spo: < 70% was an independent
predictor of ARP (odds ratio, 4.M: 95% confidence interval, 1.23 to
15.25; p = 0.02) irrespective of age and hypertension. Patients with AHI >
40/h had significantly longer isovolumic relaxation times than those with
AHI < 40/h (106 + 19 ms vs 93 ± 17 ms, respectively; p = 0.005). CON-
CLUSION: Diastolic dysfunction with ARP was common in patients
with OSA. More severe sleep apnea was associated with a higher degree
of left ventricular diastolic dysfunction in this study.

Long-Term Compliance Rates to Continuous Positive .Airwa) I'res-
surc in Obstructive Sleep Apnea: A Population-Based Study — Sin

DD, Mayers I. Man GC, Pawluk L. Chest 20(12 Feh:12 l(2):4.^(l-435.

STUDY OBJECTIVES: To determine long-term compliance rates to
continuous positive airway pressure (CPAP) therapy in patients with
obstructive sleep apnea enrolled in a comprehensive CPAP program in
the community. DESIGN: Prospective cohort longitudinal study. SET-
TING: University sleep disorders center. PATIENTS: Two hundred
ninety-six patients with an apnea-hypopnea index (AHI) > 2()/h on
polysomnography. INTERVENTIONS: A CPAP device equipped with a
monitoring chip was supplied. Within the first week, daily telephone con-
tacts were made. Patients were seen at 2 weeks, 4 weeks, 3 months, and 6
months. RESULTS: Of the 296 subjects enrolled, 81.1% were males.
Mean ± SD AHI was 64.4 ± 34.2/h of sleep; age, 51 ± 1 1.7 years; and
body mass index. 35.2 ± 7.9 kg/m-. The mean duration of CPAP use was
5.7 h/d at 2 weeks. 5.7 h/d at 4 weeks. 5.9 h/d at 3 months, and 5.8 h/d at
6 months. The percentage of patients using CPAP > 3.5 h/d was 89.0% at
2 weeks. 86.6% at 4 weeks, 88.6% at 3 months, and 88.5% at 6 months.
There was a decrease in the Epworth Sleepiness Scale (ESS) score of
44% by 2 weeks of therapy. The patients continue to improve over the
follow-up period, with the lowest mean ESS score observed at 6 months.
With multiple regression analysis, three variables were found to be sig-
nificantly correlated with increased CPAP use: female gender, increasing
age, and reduction in ESS score. CONCLUSION: A population-based
CPAP program consisting of consistent follow-up, "troubleshooting."
and regular feedback to both patients and physicians can achieve CPAP
compliance rates of > 85% over 6 months.

Spironu'try in the Supine Position lmpr()>es the Detection of
Diaphragmatic Weakness in Patients with Amyotrophic Lateral

Sclero.sis— Lechtzin N, Wiener CM, Shade DM. Clawson L, Diette GB.
Chest 2002 Feb;121(2):436-442.

STUDY OBJECTIVES: To detcrniine which lespiitilory function tests
best predicted diaphragmatic strength in patients w ith amyotrophic lateral
sclerosis, PATIENTS AND METHODS: Patients referred for pulmonary
evaluation were included (n = 25) if they underwent nieasurenienl of
transdiaphragmatic pressure (Pdi) and one or more of the following on
the same day: upright FVC. supine FVC. upright FEV|, supine FEV|.
maximal inspiratory pressure (MIPl, maximal expiratory pressure

(MEP), and Pacoi- Abdominal paradox and use of accessory muscles
were also assessed. Bivariale analyses were performed using simple lin-
ear regression. Sensitivity and specificity of the potential predictors to
detect an abnormal Pdi (< 70 cm H:0) were calculated. SETTINCi: Pul-
monary function laboratory of an academic medical center. RESULTS:
Upright FVC. FEV], and MEP were all significantly correlated with Pdi,
while MIP and P.,o>.' were not. Supine FVC was the most highly corre-
lated predictor of Pdi (R- = 0.76). A cutoff of supine FVC that was < 75%
predicted was 100% sensitive and specific for predicting an abnormally
low Pdi. Accessory muscle use and abdominal paradox were both signifi-
cantly associated with Pdi. and the presence of accessory muscle use had
a sensitivity of 84% and a specificity of 100% for detecting a low Pdi.
CONCLUSIONS: Our findings suggest that supine FVC is an excellent
:md simple test of duiphragniatic weakness.

Domiciliary-Assisted Ventilation in Patients with Myotonic Dystro-
phy—Nugent AM. Smith IE. Shneerson JM. Chest 2002 Feb;121(2K459-
464.

STUDY OBJECTIVES: Respiratory failure is louiid in many neuromus-
cular diseases, even when the lungs may be healthy, because of an inade-
quacy of the ventilatory pump. Long-term domiciliary ventilation is a
well-established treatment in conditions such as postpoliomyelitis; how-
ever, its use in patients with respiratory failure secondary to myotonic
dystrophy has not been well described. The purpose of this study was to
review the use of domiciliary-assisted ventilation in these patients and to
assess their response to treatment. DESIGN: Descriptive analysis of ret-
rospective and prospective clinical data. SETTING: Inpatient, noninva-
sive respiratory-care unit in a tertiary referral center. PATIENTS: Sixteen
patients with myotonic dystrophy, 13 of whom required ventilatory sup-
port. INTERVENTIONS AND MEASUREMENTS: A retrospective
study of all patients with myotonic dystrophy referred for assessment for
assisted ventilation was pcrlormed. including results of arterial blood gas
analysis, pulmonary function tests, and overnight oxygen saturation and
transcutaneous carbon dioxide levels. A prospective reassessment of all
patients established on domiciliary ventilation was performed, including
measurements of quality of life, RESULTS: Results of arterial blood gas
analysis showed a fall in mean Paco; from 64.3 to 53,8 mm Hg (p < 0.05)
on discharge after starting ventilation and a rise in mean P^o; from 53.0 to
65.3 mm Hg (p < 0.05). There were three deaths, at 5 months, 32 months,
and 57 months, respectively. The survivors received assisted ventilation
for a mean period of 27 months (range. 2 to 76 months). At reassessment,
improvements in arterial blood gas levels were maintained, with mean
P,iCO; of 52.4 mm Hg and PaO: of 59.0 mm Hg. Mean overnight mean
arterial oxygen saturation rose from 80.5 to 90.3% after the start of treat-
ment (p < 0.001) and was maintained at 90.4% at reassessment. Mean
transcutaneous Pco; during sleep fell from 59.3 to 41.4 mm Hg (p <
0.05). and to 43.7 mm Hg at reassessment. There were no significant
changes in spirometry or maximum mouth pressures. Compliance with
treatment for our test group was lower than compliance in a group of age-
and sex-matched postpoliomyelitis patients. CONCLUSION: Use of
domiciliary-assisted ventilation in patients with myotonic dystrophy is
:issocialed with prolonged survival and a sustained improvement in arte-
rial blood gas tensions.

Effect of Continuous Positive .Airway Pressure on the Rapid Shallow
Breathing Index in Patients Following Cardiac Surgery — El-Khatib
MF. Jamalcddine G\V. Khoury AR. Obcid MY. Chest 2002

Fcb;121(2):475-479.

OBJECTIVES: To compare the rapid shallow breathing index (RSBl)
under different ventilatory support settings prior to extubation trials.
DESIGN: Prospective study. SETTING: Cardiac surgery unit at a univer-
sity hospital. PATIENTS: A total of 33 coronary artery bypass grafting

752

RESP1RAT0R>- Carh . J LILY 2002 VOL 47 No 7

Abstracts

patients reads tor cMubation. IN TFRVF.NTIONS: Ijirnllcd palicnls
received a continuous positive airway pressure (CPAPl trial of 5 cm H^O
and fraction of inspired oxygen (F|0;) of 40' j (condition I ). a CPAP (rial
of ? cm H:0 and Fio. of 2\''i (condition 2). and a l-iiiln spontaneously
breathing room air trial without ventilatory support (condition 3). These
trials were applied in random order. Measurements and main resulis:
Average values of respiratory frequency and tidal volume were measured
under the three experimental conditions in all patients immediately prior
to extubation. The RSBIs were determined for each patient under each
condition; the average RSBIs under conditions I. 2. and 3 were comparcil
for signitlcance. The average RSBIs (± SD) were significantly smaller
under condition I l34± 1 3l and condition 2 (36 ± 14) compared to condi-
tion 3 (71 ± 24). There was no significant difference in RSBI between
conditions 1 and 2. CONCLUSIONS: The administration of 5 cm H:0 of
CPAP can influence the determination of the RSBI. In contrast, changes
in Fio., have no effect on RSBI determination. We speculate that using the
RSBI during CPAP may mislead the clinician into premature discontinu-
ation of mechanical ventilation. Consequently, different threshold values
for the RSBI should be derived for different ventilatory support levels.

Central Venous and Bladder Pressure Reflect Transdiaphragmatic
Pressure During Pressure Support Ventilation — Chieveley-Williams
S, Dinner L. Puddicombe A. Field D. Lovell AT. Goldslone JC. Che.st
2002Feb;l2l(2):-'i33-.S.W.

STUDY OBJECTIVES: To determine whether the change in bladder
pressure (Pbiad) and central venous pressure (P^p) may reflect the
changes in esophageal pressure (Pes) and gastric pressure (Pgas) when
Inspiratory pressure support (IPS) is altered. DESIGN: Prospective clini-
cal study. SETTING: The ICUs of a teaching hospital. PATIENTS: Ten
patients currently receiving IPS ventilation via a tracheostomy or an
endotracheal tube who already had bladder and central venous catheters
in situ. MEASUREMENTS AND RESULTS: Airway pressure. Pes. P„as.
Ptvp. Pbiaii- and flow were measured at the original IPS setting. IPS then
was reduced by 5-cm HiO increments until IPS was zero or was at the
minimum pressure that could be tolerated by each patient. At each level
of IPS. pressures and flow were measured at steady-state breathing. The
ma.ximum pressure difference for each pressure during inspiration was
calculated. We found that the APhijj correlated closely with the AP„js (r =
0.904) and that the APes correlated with the AP,>p (r = 0.951 1. When the
APtvp - APhiad was compared with the transdiaphragmatic pressure for
each patient as the IPS was altered, the correlation coefficients varied
from 0.952 to 0.999. CONCLUSION: Although absolute values for the
APevp during mechanical ventilation do not always reflect the APes. useful
information can be obtained from this route. In individual patients, the
two sites of measurement followed each other when IPS was changed,
enabling a bedside assessment of the response to reducing respiratory
support.

A Cross-Cultural Comparison of Critical Care Delivery: Japan and
the I'nited States — Sirio CA. Tajimi K. Taenaka N, Ujike Y. Okamoto
K. Katsuya H. Chest 2002 Feb;121(2):539-548 .

OBJECTIVE: To compare the utilization and outcomes of critical care
services in a cohon of hospitals in the United Stales and Japan. DESIGN:
Prospective data collection on 5.107 patients and detailed organizational
characteristics from each of the participating Japanese study hospitals
between 1993 and 1995. with comparisons made to prospectively col-
lected data on the 17.440 patients included in the US APACHE (acute
physiology and chronic health evaluation) III database. SETTING:
Twenty-two Japanese and 40 US hospitals. PATIENTS: Consecutive,
unselected patients from medical, surgical, and mixed medical/surgical
ICUs. MEASUREMENTS: Severity of illness, predicted risk of in-hospi-
tal death, and ICU and hospital length of stay (LOS) were assessed using
APACHE 111. Japanese ICU directors completed a detailed survey

describing their units. MAIN RESULTS: US and Japanese ICUs have a
similar array of modalities available for care. Only I.O'/t (range. 0.5ft to
2.7'r ) of beds in Japanese hospitals were designated as ICUs. The organi-
zation of the Japanese and US ICUs varied by hospital, but Japanese
ICL's were more likely to be organized to care for heterogeneous diagnos-
tic populations. Sample case-mix differences reflect diflerent disease
prevalence. ICU utilization for women is significantly lower (35.5% vs
44.8'/r of patients) and there were relatively fewer patients > 85 years old
in the Japanese ICU cohort ( 1.2"^ vs 4.6%). despite a higher per capita
rate ol individuals > 85 years old in Japan. The utilization of ICUs for
patients at low risk of death significantly less in Japan ( 10. 2'* I than in the
Linited States (12.9%). The APACHE III score stratified patient risk.
Overall mortality was similar in both national samples after accounting
for differences in hospital LOS. utilizing a model that was highly discrim-
inating (receiver operating characteristic. 0.87) when applied to the
Japanese sample. The application of a US-based mortality model to a
Japanese sample overestimated mortality across all but the highest (>
90% ) deciles of risk. Significant variation in expected pert'ormance was
noted between hospitals. Risk-adjusted ICU LOS was not significantly
longer in Japan: however, total hospital stay was nearly twice that found
in the US hospitals, rellecling differences in hospital utilization philoso-
phies. CONCLUSIONS: Similar high-technology critical care is avail-
able in both countries. Variations in ICU utilization reflect differences in
case-mix and bed availability. Japanese ICU utilization by gender reflects
differences in disease prevalence, whereas differences in utilization by
age may reflect differences in cultural norms regarding the limits of care.
Such differences provide context from which to assess the delivery of
care across international borders. Miscalibration of predictive models
applied to international data samples highlight the impact that differences
in resource use and local practice cultures have on outcomes. Models may
require modification in order to account for these differences. Neverthe-
less, with large databases, it is possible to assess critical care delivery sys-
tems between countries accounting for differences in case-mix. severity
of illness, and cultural normative standards facilitating the design and
management such systems.

2-Month Mortality and Functional Status of Critically III Adult
Patients Receiving Prolonged Mechanical \ entilation — Quality of
Life After Mechanized Ventilation in the Elderly Study Investigators.
Chest 2002 Feb:l2l(2):-549-558.

STUDY OBJECTIVES: To describe the 2-month mortality and func-
tional status of adult patients receiving prolonged (at least 48 h) mechani-
cal ventilation (MV), and to identify patient characteristics that are asso-
ciated with 2-month mortality. DESIGN: Prospective cohort study.
SETTING: Four ICUs at a tertiary-care institution. PATIENTS: Eight
hundred seventeen patients who received prolonged MV. INTERVEN-
TIONS: None. MEASUREMENTS AND RESULTS: Median age. sex
distribution, and median Charlson comorbidity score of the 817 patients
were 65 years, 45.8% women, and I. respectively. The median scores on
Katz Activities of Daily Living, Instrumental Activities of Daily Living
Deficits, and Medical Outcomes Study Short-Form 36 surveys before
hospitalization were 0, 1, and 50. respectively. Median APACHE (acute
physiology and chronic health evaluation) III score and probability of
hospital death for the cohort were 64 and 0.3 1 . respectively. Median dura-
tion of M V was 9 days. Two-month mortality was 43%. Independent pre-
dictors of mortality at 2 months were age. comorbidities, and prehospital
functional status. The adjusted odds of dying within 2 months increased
34% for each decade increase in age. Functional status deteriorated at 2
months compared to functional status prior to hospitalization, and 35% of
the survivors were at risk for clinical depression. Among the 2-month sur-
vivors for whom the need for a caregiver was assessed, 78% had a care-
giver. CONCLUSIONS: Older age, in addition to functional status and
comorbidities, was associated with increased mortality at 2 months.
Functional status of survivors declined at 2 months.

RESPIRATORY CARE . JULY 2002 VOL 47 NO 7

753

ABSTRACTS

A Systematic Review of the Effects of Bronchodilators on Exercise
Capacitj in Patients with C'OPD- l.icskcr JJ, Wi|ksira PJ. Ten Hacken
NH, Koeter GH. PoMiiia DS, Kcrstjens HA. Chest 2002 Feb; 1 2 1(2 1:597-
608.

One of the major goals of hronchodilalor therapy in patients with
COPD is to decrease airflow limitation in the airways and. as a conse-
quence, improve dyspnea and exercise tolerance. The focus of this
systematic review is to assess the effects of treatment with 6-agonists,
anticholinergics, and theophyllines on dyspnea, and steady-state and
incremental exercise capacity. Thirty-three, double-blind, random-
ized, placebo-controlled studies written in English were selected. This
review shows that approximately half of the studies showed a signifi-
cant effect of bronchodilator therapy on exercise capacity. Anticholin-
ergic agents have significant beneficial effects in the majority of stud-
ies, especially when measured by steady-state exercise protocols.
There is a trend toward a better effect of high-dose compared to low-
dose anticholinergics. Short-acting Bi-mimetics have favorable
effects on exercise capacity in more than two thirds of the studies;
surprisingly, the situation is less clear for long-acting Bi-agents. The
majority of the results of the published reports on theophyllines and
their effects on exercise are negative. Direct comparisons of different
classes of bronchodilators have not been made in a sufficient number
of studies for a rational preference. The addition of a second bron-
chodilator has no proven advantage for improving exercise test
results, but this has not been studied extensively and not in suffi-
ciently large studies. The majority of studies reporting a measure of
dyspnea found improvements, even in the absence of improvement in
exercLse capacity.

COPD and Osteoporosis— Biskobing DM. Chest 2002 Feb;121(2):609-
620.

Osteoporosis, with resulting fractures, is a significant problem in patients
with advanced COPD. The etiology for the bone loss is diverse but
includes smoking, vitamin D deficiency, low body mass index, hypogo-
nadism, sedentary lifestyle, and use of glucocorticoids. Effective strate-
gies to prevent bone loss and/or to treat osteoporosis include calcium and
vitamin D. hormone replacement when indicated, calcitonin, and bispho-
sphonate administration. However, many patients remain undiagnosed
until their first fracture because of the lack of recognition of the disease.
With an increased awareness by pulmonologists and the increased use of
preventive strategies, the impact of osteoporosis on those patients with
COPD should decrease.

Pulmonary Edema Caused by Inhaled Nitric Oxide Therapy in Two
Patients with Pulmonary Hypertension Associated with the CREST
Syndrome — Preston IR. Klinger JR. Houtchens J. Nelson D. Mehta S.
Hill NS. Chest 2002 Feb;121(2):656-6.'i9.

Pulmonary arterial hypertension (PAH) is commonly associated with the
CREST (calcinosis, Raynaud phenomenon, esophageal dysmotility. scle-
rodactyly, telangiectasia) syndrome. Inhaled nitric oxide (iNO) is often
used to assess acute vasoresponsiveness in patients with PAH, and
reports of adverse reactions have been infrequent. We describe two of
nine patients with PAH and CREST syndrome who had pulmonary
edema develop during acute iNO testing. This complication was not
encountered in the 46 patients with other forms of PAH tested with iNO.
We suggest that INO should be used with caution, if at all. to test acute
vasoreactivity in patients with CRF.ST syndrome.

DitTust Panhnmchiolitis: A Treatable Sinobrunchial Disease in Need
of Recognition in the finited States — Krishnan P. Thachil R. Gillego V.

Chest 2(102Feb;i21(2):6.Sy-661.

Diffuse panbronchiolitis (DPB) is a progressive inflammatory disease,
well recogm/ed in Japan, characterized by sinusitis and obstructive small
airway disease; if left untreated, it progresses to bronchiectasis, respira-
tory failure, and death. Treatment using low-dose erythromycin has
proven to be highly eft~icacious. Lack of familiarity with DPB in the
United States may result in the failure to correctly diagnose and treat this
disorder. We describe a Cambodian man in whom the characteristic
imaging and histologic features of DPB were elicited but not recognized
in spite of evaluation at a referral center. When DPB was diagnosed 6
years later, he was in respiratory failure, but made an excellent recovery
once erythromycin therapy was instituted. We report this case to increase
physician awareness of DPB as a cause of sinobronchial disease and dis-
cuss its diagnostic features so that the disease is recognized and treated
without delay.

Alteration of Contractile Force and Mass in the Senescent
Diaphragm with li2-Agonist Treatment — Smith WN. Dirks A, Sugiura
T, Muller S, Scarpace P, Powers SK. J Appl Physiol 2002 Mar.92(3):94l-
94X.

Aging is associated with a decrease in diaphragmatic maximal tetanic
force production (P,,) in senescent rats. Treatment with the Bi-agonist
clenbuterol (CB) has been shown to increase skeletal muscle ma,ss and Po
in weak locomotor skeletal muscles from dystrophic rodents. It is
unknown whether CB can increase diaphragmatic mass and Po in senes-
cent rats. Therefore, we tested the hypothesis that CB treatment will
increase specific Pn (i.e., force per cross-sectional area) and mass in the
diaphragm of old rats. Young (5 mo) and old (23 mo) male Fischer 3-M
rats were randomly assigned to one of the following groups 'n =
10/group): 1 ) young CB treated; 2) young control; 3) old CB treated; and
4) old control. Animals were injected daily with either CB (2 mg/kg) or
saline for 28 days. CB increa.sed (p < 0.05) the mass of the costal
diaphragm in both young and old animals. CB treatment increased
diaphragmatic-specific P„ in old animals (approximately 15%; p < 0.05)
but did not alter (p > 0.05) diaphragmatic-specific Po in young animals.
Biochemical analysis indicated that the improved maximal specific Po in
the diaphragm of CB-treated old animals was not due to increased
myofibrillar protein concentration. Analysis of the myosin heavy chain
(MHO content of the costal diaphragm revealed a CB-induced Increase
(p < 0.05) in type lib MHC and a decrease in type I. Ila. and llx MHC in
both young and old animals. These data support the hypothesis that CB
treatment can restore the age-associated decline in both diaphragmatie-
specitic P,, and muscle mass.

Nitric Oxide Mediates Hypoxla-Induced Cerebral Vasodilation in
Humans— Van Mil AH. Spilt A. Van Buchem MA. Bollen EL,
Teppema L. Westendorp RG, Blauw GJ. J Appl Physiol 2002
Mar;92(3):962-966.

Nitric oxide (NO) plays a pivotal role in the regulation of peripheral vas-
cular tone. Its role in the regulation of cerebral vascular tone in humans
remains to be elucidated. This study investigates the role of NO in
hypoxia-induced cerebral vasodilatation in young healthy volunteers. The
effect of the NO syntha.se inhibitor N(G)-monomethyl-L-arginine (L-
NMMA) on the cerebral blood flow (CBF) was assessed during normoxia
and during hypoxia (peripheral O: saturation 97 and 809r. respectively).
Subjects were positioned in a magnetic resonance scanner, breathing nor-
mal air (normoxia) or a N^- O: mixture (hypoxia). The CBF was mea-
sured before and after administration of L-NMM.^ (3 mg/kg) by use of
phase-contrast magnetic resonance imaging techniques. Administration
of L-NMMA during normoxia did not affect CBF. Hypoxia increased
CBF from l.(U9 ± 113 to 1.209 ± 143 mL/min (p < 0.05). After L-
NMMA administration, the augmented CBF returned to baseline ( 1 .050 ±
161 mL/min; p < 0.05). Similarly, cerebral vascular resistance declined
during hypoxia and returned to baseline alter administration of L-NMMA

754

Rh.spir.atory Care . July 2002 Vol 47 No 7

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ABSTRACTS

(p < 0.05 for both). Use of phase-contraM magnetic resonance imaging
shows that hypoxia-induced cerebral vasodilatation in humans is medi-
ated by NO.

Kioenerci'tie Aduplallon of Individual Human Diuphra^imatic
.NlMiUhers In Severe COI'I) — l.cMiii.- .S. (irci;iM> C. Ngu\en T. Shrager
J, Kaiser L. Rubinstein N. Dudley G. J Appi Physiol 21)0:
Mar;92(3):1205-I2l3.

To assess the effect of severe chronic obstructive pulmonary disease
(COPD) on the ability of human diaphragmatic myofibers to aerobi-
cally generate ATP relative to ATP utili/ation. we obtained biopsy
specimens of the costal diaphragm from seven patients with severe
COPD (mean + SE; age 56 ± I yr; forced expiratory volume in I s 23 ±
2% predicted; residual volume 267 ± 30'* predicted) and seven age-
matched control subjects. We categori/ed all fibers in these biopsies
by using standard techniques, and we carried out the following quanti-
tative histochemical measurements by microdensitometry: 1) succinate
dehydrogenase (SDH) activity as an indicator of mitochondrial oxida-
tive capacity and 2) calcium-acti\aicd myosin ATPase (mATPase)
activity, the ATPase that represents a major portion of ATP consump-
tion by contracting muscle. We noted the following: 1 ) COPD
diaphragms had a larger proportion of type I fibers, a lesser proportion
of type Ilax fibers, and the same proportion of type lla fibers as con-
trols. 2) SDH activities of each of the fiber types were higher in COPD
than control diaphragms (p < 0.0001); the mean increases (expressed
as percent of control values) in types I. Ila. and Ilax were 84, 1 14, and
IBC;}-, respectively. 3) COPD elicited no change in mATPase activity
of type I and Ila fibers, but mATPase decreased in type Ilax fibers (p =
0.02). 4) Mitochondrial oxidative capacity relative to ATP demand
(i.e., SDH/mATPase) was higher (p = 0.03) in each of the fiber types in
COPD diaphragms than in controls. These results demonstrate that
severe COPD elicits an increase in aerobic ATP generating capacity
relative to ATP utilization in all diaphragmatic fiber types as well as
the previously described fast-to-slow fiber type transformation (Levine
S. Kaiser L, Leferovich J. and Tikiinov B. N Engl J Med 337: 1799-
1806, 1997).

Effect of Positive Pressure on Venous Return in Volume-Loaded
Cardiac Surgical Patients — van den Berg PC. Jansen JR. Pinsky MR. J
AppI Physiol 2002 Mar:92(3):l223-I23l.

The hemodynamic effects of increases in airway pressure (Pan) are
related in part to Pa»-induced increases in right atrial pressure (Pra). the
downstream pressure for venous return, thus decreasing the pressure
gradient for venous return. However, numerous animal and clinical
studies have shown that venous return is often sustained during ventila-
tion with positive end-expiratory pressure (PEEP). Potentially, PEEP-
induced diaphragmatic descent increases abdominal pressure (Pabj). We
hypothesized that an increase in Pj„ induced by PEEP would minimally
alter venous return because the associated increase in P„ would be par-
tially offset by a concomitant increase in Pahj. Thus we studied the
acute effects of graded increases of Paw on Pra, Pabd- and cardiac output
by application of inspiratory-hold maneuvers in sedated and paralyzed
humans. Forty-two patients were studied in the intensive care unit after
coronary artery bypass surgery during hemodynamically stable, tluid-
resuscilated conditions. P,m was progressively increased in steps of 2 to
4 cm HiO from 0 to 20 cm HiO in sequential 2.'i-s inspiratory-hold
maneuvers. Right ventricular (RV) cardiac ou(put (COu) and RV ejec-
tion fraction (EF,J were measured at 5 s into the inspiratory-hold
maneuver by the thermodilution technique. RV end-diastolic volume
and stroke volume were calculated from EF,, and heart rate data, and
Pra was measured from the pulmonary artery catheter. Pabd was esti-
mated as bladder pressure. We found that, although increasing Pj„ pro-

gressively increased Pra. neither CO^ nor RV end-diastolic volume
changed. The ratio of change (A) in Pan to A Pra was 0.32 ± 0.20. The
ratio of A P,a to A CO,j was 0.05 ± 00. 1 5 I x min ' x mm Hg ' . However,
Pahii increased such that the ratio of A P,a to A Pabd was 0.73 ± 0.36,
meaning that most of the increase in Prj was reflected in increases in
P,ihj We conclude that, in hemodynamically stable tluid-resuscitated
postoperative surgical patients, inspiratory-hold maneuvers with
increases in Pan of up to 20 cm HiO have ininimal effects on cardiac
output, primarily because of an in-phase-associated pressurization of
the abdominal compartment associated with compression of the liver
and squeezing of the lungs.

Asthma in Exercising Children Exposed to Ozone: A Cohort Study —

McConnell R. Berhane K. Gilliland F, London SJ. Islam T. Gaudemian
WJ. e( al. Lancet 2002 Feb 2:359(9304):386-.39l.

BACKGROUND: Little is known about the elfect of exposure to air
pollution during exercise or time spent outdoors on the development
of asthma. We investigated the relation between newly-diagnosed
asthma and team sports in a cohort of children exposed to different
concentrations and mixtures of air pollutants. METHODS: 3535 chil-
dren with no history of asthma were recruited from schools in 12 com-
munities in southern California and were followed up for up to 5
years. 265 children reported a new diagnosis of asthma during follow-
up. We assessed risk of asthma in children playing team sports at
study entry in six communities with high daytime ozone concentra-
tions, six with lower concentrations, and in communities with high or
low concentrations of nitrogen dioxide, particulate matter, and inor-
ganic-acid vapour. FINDINGS: In communities with high ozone con-
centrations, the relative risk of developing asthma in children playing
three or more sports was 3.3 (95% CI 1.9-5.8). compared with chil-
dren playing no sports. Sports had no effect in areas of low ozone con-
centration (0.8, 0.4-1.6). Time spent outside was associated with a
higher incidence of asthma in areas of high ozone (1.4, 1.0-2.1), but
not in areas of low ozone. Exposure to pollutants other than ozone did
not alter the effect of team sports. INTERPRETATION: Incidence of
new diagnoses of asthma is associated with heavy exercise in commu-
nities with high concentrations of ozone, thus, air pollution and out-
door exercise could contribute to the development of asthma in chil-
dren.

Factors Determining Cardiac Nurses' Intentions to Continue Using a
Smoking Cessation Protocol — Bolman C. de Vries H. Mesters I. Heart

Lung 2002 Jan-Feb;31( I ): 15-24.

OBJECTIVE: Our objective was to facilitate the continued use of a
smoking cessation protocol among cardiac nurses by assessing their
intentions and motives for continuation. A model that coinbines atti-
tude, social influence, and self-efficacy constructs as predictors of
intentions (ASE model) served as the theoretical framework. SET-
TING: The study took place in the cardiology wards of 5 hospitals.
RESPONDENTS: Respondents were 85 nurses who worked in the car-
diology wards of the hospitals. OUTCOME MEASURES: The out-
come measures were nurses' intentions and motives for continuing to
use a smoking cessation protocol for patients who smoke. RESULTS:
Greater perceived simplicity and advantages of the protocol were as.so-
ciated with increased intentions to continue, whereas perceived social
inlluences and self-efficacy were not. The influence of the level of
experience in using the protocol and the nurses' own smoking behavior
was mediated by attitude about the smoking cessation protocol. CON-
CLUSIONS: Nurses who do not intend to continue using the protocol
need to be convinced of the advantages of working with such a proto-
col and of its user-friendliness.

756

RESPIRATORY CARE . JULY 2002 VOL 47 NO 7

Editorials

Secretion Clearance Techniques:
Absence of Proof or Proof of Absence?

Healthy lungs clear mucus from the airways via the
mucociliary escalator. When the mucociliary escalator is
challenged in disease, secretions are cleared with the cough
reflex. Acute and chronic respiratory diseases are com-
monly associated with increased respiratory secretions due
to increased mucus production, impaired mucociliary trans-
port, or a weak cough. Howe\er. it is unknown whether
increased respiratory secretions contribute to the deterio-
ration of respiratory function, or whether this is merely a
symptom associated with the progression of the disease.
Moreover, increased mucus expectoration does not neces-
sarily imply mucus stasis in the airways.

Clinicians and patients are troubled by respiratory se-
cretions, and standard practice calls for efforts to clear
these from the lungs. An important proportion of respira-
tory therapists" time is spent in efforts to remove secre-
tions from the lower respiratory tract. For patients with
diseases such as cystic fibrosis a great deal of each day can
be spent using techniques designed to enhance secretion
clearance. In recent years a variety of techniques for se-
cretion clearance ha\e become available. Many of these
techniques are described in this issue of Respiratory Care.
Despite clinical enthusiasm for many of these by both
clinicians and patients, there is sparse high-level evidence
demonstrating benefit from many of these techniques. As
pointed out by others' '-* and me,'^ there are a number of
methodologic limitations of published reports of secretion
clearance techniques. Most studies are small and use cross-
over designs (rather than randomized parallel designs).
Sham therapy was not used in most studies — often one
technique was compared to another (for example, chest
physiotherapy \ s positive expiratory pressure). Many stud-
ies were limited to short-term outcomes such as sputum
clearance with a single treatment session. It might be ar-
gued that short-term outcomes are irrelevant and that the
focus should be on long-term outcomes such as disease
progression. qualit\ of life, and patient satisfaction.

Conducting a methodologically strong study (ie. place-
bo-controlled prospecti\e randomized trial) with an ade-
quate sample size and iinportant outcomes (eg. disease
progression, morbidity, mortality i is difficult. Such a study
would be expensi\e and industrial support is not likely.
Moreover, secretion clearance is an integral component of
disease management for patients with increased sputum

production, raising seritius ethical concerns about placebo-
controlled studies. 1 have always found it intriguing that a
new drug to improve secretion clearance must pass through
the usual Phase 1 through Phase 3 approval process, whereas
a new device is not subjected to the same scrutiny.

Is absence of proof the same as proof of absence? Does
the lack of evidence mean lack of benefit? Is the lack of
evidence due to study methodology, or is there really no
benefit from many techniques used to enhance secretion
clearance? Although we should not be dogmatic about
endorsing a therapy with absence of proof of its benefit,
we must also not be dogmatic about abandoning a therapy
because of absence of proof of its benefit — absence of
proof is not proof of absence. In fact, from a methodolog-
ical and statistical standpoint, absence of proof is very
difficult to prove. Gi\en a lack of e\idence. 1 suggest the
following clinical hierarchy t)f questions when considering
secretion clearance therapy for a patient.

1. Is there a pathophysiologic rational for use of the
therapy? Is the patient experiencing difficulty clearing se-
cretions? Are retained secretions affecting lung function in
an important way. such as gas exchange or lung mechan-
ics? Remember that the production of large amounts of
sputum does not necessarily mean that the patient is ex-
periencing difficulty clearing sputum.

2. What is the potential for adverse effects from the
therapy? Which therapy is likely to provide the greatest
benefit with the least harm?

3. What is the cost of the equipment for this therapy?
Some devices are very expensive.

4. What are the preferences of the patient? Lacking
evidence that any technique is superior to another, patient
preference is an important consideration.

When a decision is made to try a secretion clearance
technique, an H-of-1 trial can be conducted.'" "* For ex-
ample, imagine that a decision is made to try positive
expiratory pressure therapy for a patient with cystic fibro-
sis. The clinician and patient agree that a clinically useful
outcome measure is sputum production. A 12-week trial is
designed. For I week, the only sputum clearance tech-
nique used is huff coughing. Fi)r a second week, positive
expiratory pressure (in addition to huff coughing) is used,
as provided b> the manufacturer. For a thiid week, the
positive expiratory pressure device is used v\ith pressure

Respiratory C.\re • Jll-i 2002 Vol 47 No 7

757

Secretion Clearance Techniques: Absence of Proof or Proof of Absence?

set al such a low le\el that it is probably suh-therapoutic
(sham therapy). The patient is naive to the therapy and
does not knou whether the device should be used w ilh or
without the high-pressure setting. The order ol' treatments
is randomized (the patient flips a coin) and the sequence is
repeated 4 times. Each day. the sputum produced during
the therapy session is weighed. A diary is also kept, in
vshich e\enls such as chest infections are logged. At the
end of 12 weeks the results are analyzed (this may include
statistical analysis), reviewed together by the clinician and
patient, and a collaborative decision is made regarding the
benefit of the therapy. In this manner an objective decision
is made regarding the benefits oi the therapy for this in-
dividual patient.

Despite the clinical observation that retained secretions
are detrimental to respiratory function and despite anec-
dotal associations between secretion clearance and im-
provements in respiratory function, there is a dearth of
high-level evidence to support any secretion clearance tech-
nique. This is problematic, given that secretion clearance
is an important aspect of respiratory care practice. Al-
though lack of evidence does not mean lack of benefit, it
is desirable to have better evidence to support the practice.
Appropriately powered and methodologically sound re-
search is desperately needed. This provides an opportunity
for respiratory therapists to conduct research on a very
important aspect of our practice. For the effective therapy
of our patients and for the efficient use of health care
resources, it is incumbent upon us to improve the scientific
basis for secretion clearance techniques.

Dean R Hess PhD RRT FAARC

Department of Respiratory Care

Massachusetts General Hospital

Harvard Medical School

Boston, Massachusetts

Correspondence: Dean R Hess PliD RRT F.'V.ARC. Department of Re-
spiratory Care Services, Massacliusetls General Hospital. 55 Fruit Street.
Ellison 401. Boston MA 0211-1-2696. Email: (Jliess@partners.org.

REFERENCES

1 . Stiller K. Pliysiotherapy in intensive care: tou ards an evidence-based
practice. Chest 20()();1 18(6):1801-I8I3.

2. Williams MT. Chest physiotherapy and cystic tlhrosis. Why is the
most effective tbrin of treatment still unclear? Chest 1994:106(6):
IS72-1882.

3. Krause MF. Hoehn T. Chest physiotherapy in mechanically venti-
lated children: a review. Crit Care Med 2000:28(5): 1648- 1651.

4. McCrory DC. Brown C. Gelfand SE, Bach PB. Management of acute
exacerbations of COPD; a summary and appraisal of published ev-
idence. Chest 2001;119(4):l 190-1209.

5. Dean E, Ross J. Discordance between cardiopulmonary physiology
and physical therapy: toward a rational basis for practice. Chest
1992:101(61:1694-1698.

6 Kirilloff LH. Owens GR. Rogers RM. Mazzocco MC. Does chest
physical therapy work.' Chest 1985:88(31:436-444.

7. Wallis C, Prasad A. Who needs chest physiotherapy? Moving from
anecdote to evidence. Arch Dis Child 1999;80(4):393-397.

8. Judson MA. Sahn SA. Mobilization of secretions in ICU patients.
RespirCare 1994:39(3):213-226.

9. Eid N. Buchheit J, Neuling M, Phelps H. Chest physiotherapy in
review. Respir Care 1991:36(4):270-282.

10. Thomas J. Cook DJ. Brooks D. Chest physical therapy management
of patients with cvstic fibrosis: a meta analysis. Am J Respir Cril
Care Med 1995:151(3 Pt 1): 846-850.

1 1. Jones A, Rowe BH. Bronchopulmonary hygiene physical therapy in
bronchiectasis and chronic obstructive pulmonary disease: a system-
atic review. Hean Lung 2000;29(2):125-135.

12. Thomas J, DeHueck A. Kleiner M. Newton J, Crowe J, Mahler S.
To \ ibrate or not to vibrate: usefulness of the mechanical vibrator
for clearing bronchial secretions. Physiother Can 1 995:47(2 ): 120-
125.

13. van der Schans C. Prasad A. Main E. Chest physiotherapy compared
to no chest physiotherapy for cystic fibrosis. Cochrane Database Syst
Rev 2000;(2):CD001401.

14. Flenady VJ. Gray PH. Chest physiotherapy for preventing morbidity
in babies being extubated from mechanical ventilation. Cochrane
Database Syst Rev 20O0;(2):CDO0O283.

15. Hess DR. The evidence for secretion clearance techniques. Respir
Care 2001:46( 1 1 ):1276-1293.

16. Guyatt G. Sackett D. Taylor DW. Chong J. Roberts R. Pugsley S.
Determining optimal therapy: randomized trials in individual pa-
tients. N Engl J Med 19S6;3I4( 14):889-892.

17. Guyatt G. Sackett D. Adachi J, Roberts R. Chong J. Rosenbloom D,
Keller J. A clinician's guide for conducting randomized trials in
individual patients. CMAJ 1988;l39(6):497-503.

18. Montori VM. Guyatt GH. What is evidence-ba.sed medicine and why
should it be practiced' RespirCare 2()01:46( 1 1 ):1201-I21 1.

758

Respirators Care • July 2002 Vol 47 No 7

Foreword

New Horizons in Respiratory Care:
Airway Clearance Techniques

It was an honor to co-chair the 17th Annual New Ho-
rizons Symposium at the American Association tor Respi-
ratory Care's International Respiratory Congress in San
Antonio, Texas, on December 2, 2001. The New Horizons
Symposium has been a landmark feature of the meeting
for 17 years. This full-afternoon session provides a com-
prehensive, focused, and multi-dimensional exploration of
a key aspect of the practice of respiratory care, usually
reviewing areas of evolving clinical practice. In many in-
stances the manuscripts from the symposium are then pub-
lished in a special issue of Respirator'. Cari-:.

Airway mucus is a critically important host defense.
Normal mechanisms for mobilization of secretions include
mucociliary transport, autocephalad flow (secretions mov-
ing toward the central airway during normal breathing),
and cough. Mucus hypersecretion and impaired mucus
clearance can be serious problems, leading to discomfort,
dyspnea, airway obstruction, atelectasis, infection, bron-
chiectasis, and pulmonary disability. As respiratory care
has evolved as a profession, airway secretion clearance has
always been part of our scope of practice.' -* Terms such
as "bronchial hygiene" and "pulmonary toilet" have been
used to characterize the process of assisting patients to
clear airway secretions. Too often, however, those terms
have been associated only with postural drainage, percus-
sion and vibration, or mechanical aspiration of the airways
in acutely ill patients.

Over the past 40 years we have come to better under-
stand the mechanisms of airway clearance in health and
disease, and this has led to the development of devices
and techniques to assist in secretion removal. The amount
and quality of evidence from rigorously conducted, ran-
domized clinical trials in support of these diverse tech-
niques varies widely.^ However, most of the techniques
are based on physiologic rationale and are at least sup-
ported by case studies. -

This year's New Horizons Symposium began with a
review of the "Physiology of Airway Mucus Clearance"
(Bruce Rubin). The major bronchial hygiene techniques
were reviewed in "Positioning Versus Postural Drainage"
(Jim Fink). "Airway Physiology, Autogenic Drainage, and

Active Cycle of Breathing" (Craig Lapin). "Positive Pres-
sure Techniques" (Jim Fink), and "High-Frequency Oscil-
lation of the Airway and Chest Wall" (Mike Mahlmeister
and Jim Fink). Kathy Davidson discussed "Airway Clear-
ance Strategies for the Pediatric Patient" and presented
strategies for introducing these techniques as the patient
develops from infancy through to adulthood. Robert Lewis
then reviewed key practice considerations for the intu-
bated patient in or out of the intensive care unit in "Airway
Clearance Techniques for the Patient with an Artificial
Airway." Dr Rubin's review of "The Pharmacologic Ap-
proach to Airway Clearance: Mucoactive Agents" then
summarized the state of the art for medical management of
secretion retention.

As we concluded the symposium it was clear that we
had not addressed one potentially valuable method of air-
way clearance: ultra-low-frequency airway oscillation, bet-
ter known as the Insuftlator/Exsuftlator (Fig. I). This de-
vice has been studied for more than 50 years. Evidence
suggests that it is an effective method to assist airway
clearance in debilitated patients or in those with severe
neuromuscular weakness.

The symposium participants agreed that although there
may be few data to unequivocally support the use of many
of these techniques, there is strong observational evidence

Fig. 1. Mechanical In-Exsufflator. (Courtesy JH Emerson Com-
pany, Cambridge, Massachusetts.)

Respiratory Care • July 2002 Vol 47 No 7

7.59

New Horizons in Respirators Care: Airway Clearance Techniques

Order Tor poslural
drainage

Poilurat diiintgc noi

indicaied Evaluiic for

lung expansion

Tutu frequenlly

Inmate PAP

Assure sec re Hon

ticarancc from airway

Inslnici m directed

cough. ACB.FET

Instruct in dcrp breathing, ^
splinting, and dirccied cough

fcncourage patici
dcep-brcaihc and

Iniiiatfr'intmjci to uic
incentive spi(timeir>
every hour while avt^kc

Fig. 2. Flow diagrams for protocolized treatment options in response
to order for (A) postural drainage and (B) lung expansion therapy.
ACB = active cycle of breathing technique. ASAP = as soon as pos-
sible. CF = cystic fibrosis. FET = forced expiratory technique. HFO =
high-frequency oscillation. IPPB = intermittent positive pressure breath-
ing. PAP = positive airway pressure. PEP = positive expiratory pressure.
(Adapted from Reference 1 .)

that suggest that many of these techniques can have a role
in nu)bili/ing secretions, reducing dyspnea, and helping
patients mainlain paleni airways. Selection of a "best"
technique is currenlly more of an art than a science and
depends greatly on the patient's underlying condition, level
of functioning and understanding, and ability and willing-
ness to perform the technique and integrate it into normal
daily routines. For the clinician, the decision diagrams in
Figure 2 represent one approach for technique selection.
Education is key to the success of any technique. The
better a patient understands a technique the better chance
the patient has of adopting it appropriately.

Future research needs to better define and refine tech-
niques in use and to incorporate good study designs in
well-powered clinical trials that use meaningful out-
coines. As an example, although often measured, the
volume of expectorated sputum is of limited or no value
in determining the clinical effectiveness of these de-
vices and techniques. Measuring the frequency of pvo-
tocol-defined exacerbations, antibiotic use. unplanned
physician visits, hospitalizations, or missed days of work
or school appears to be of greater clinical and scientific
relevance. The more that we as a profession invest in
learning, teaching, and studying these techniques, the
greater the chance that our patients can benefit from
their use.

James B Fink MSc RRT FAARC

Fellow, Respiratory Science

Aerogen Incorporated

San Francisco. California

Bruce K Rubin MEngr MD FAARC

Department of Pediatrics

Wake Forest University School of Medicine

Winston-Salem. North Carolina

REFERENCES

1. Fink JB. Bronchial hygiene and lung expansion. In: Fink JB. Hum .1,
editors. Clinical practice of respiratory care. Philadelphia: Ra\en-
Lippincott: 1999.

2. Fink JB, Hess DR. Secretion clearance techniques. In: Hess DR.
Maclntyre NR, et al. editors. Respiratory care: principles and prac-
lices. Philadelphia: W'B Saunders: 2002.

3. American Association lor Respiratory Care. A.ARC Clinical Practice
Guideline: Postural drainage therapy. Respir Care 1 99 1 :36(l 2 ): 1 4 1 8-
1426.

4. Fink JB, King M. Mechanical methods of mucus clearance. In: Rubin
B. Van der Schans CP. editors. Therapy for mucus clearance disorders:
lung biology in health and disea.se. New York: Marcel Dekker (in press).

.s. Hess DR. The evidence for secretion clearance techniques. Respir
Care 200I:46( 1 1 ):I276-I292.

760

Respiratory Care • Jli.'i 2002 Vol 47 No 7

Symposium Papers

Physiology of Airway Mucus Clearance

Bruce K Rubin MEngr MD FAARC

Introduction

Role of Mucus in Mucociliary Clearance

Mucus Properties

Sputum
Cilia

Airway Surfactant
Cough Clearance

Role of Inflammation

Chest Physical Therapy
Summary

Respiratory tract secretions consist of mucus, surfactant, and periciliary fluid. The airway surface
fluid is present as a bilayer, with a superficial gel or mucous layer and a layer of periciliary fiuid
interposed between the mucous layer and the epithelium. A thin layer of surfactant separates the
mucous and periciliary fluid layers. The mucous layer extends from the intermediate airway to the
upper airway and is approximately 2-10 juim thick in the trachea. Airway mucus is the secretory
product of the goblet cells and the submucosal glands. It is a nonhomogeneous, adhesive, viscoelastic
gel composed of water, carbohydrates, proteins, and lipids. In health, the mucous gel is primarily
composed of a 3-dimensional tangled polymer network of mucous glycoproteins or mucin. Mucin
macromolecules are TO-SO'?? carbohydrate, 20% protein, and 1-2 '7f sulfate bound to oligosaccha-
ride side chains. The protein backbones of mucins are encoded by mucin genes (MUC genes), at
least 8 of which are expressed in the respiratory tract, although MUC5AC and MUC5B are the 2
principal gel-forming mucins secreted in the airway. Mucus is transported from the lower respi-
ratory tract into the pharynx by air fiow and mucociliary clearance. Kxpectorated sputum is
composed of lower respiratory tract secretions along with nasopharyngeal and oropharyngeal
secretions, cellular debris, and microorganisms. Disruption of normal secretion or mucociliary
clearance impairs pulmonary function and lung defense and increases risk of infection. When there
is extensive ciliary damage and mucus hypersecretion, airflow -dependent mucus clearance such as
cough becomes critically important for airway hygiene. Key words: imiciis. sputum, coiii^h. cilia,
miicociliitrx cli'tirancc. siirfactiint. suhniucdSdl i^lmuls. golylet cells, cystic fibrosis, chronic bronchitis,
asthma. [Respir Care 2002;47(7):761-7681

Introduction estimated that mucus secretion volume is between 10 and

100 mL per day in health.' Airway mucus is a viscoelastic
Mucus secretion and clearance are extremely important
for airway integrity and pulmonary defense. It has been

Horizons Symposium :il llic 47lh liucriiLilion;il Rcsplruloiy Congress, San

Antonio. Texas, December 14. 20(11.

Bruce K Rubin MEngr MD FAARC is afhlialed uitli the Department of

Pediatrics, Wake Forest University School of Medicine, Winston-Salem, Correspondence: Bruce K Rubin MEngr MD FAARC. Department

North Carohna "' Pediatrics. Wake Forest llniversily School ol Medicine, Medical Cen-

ter Boulevard. Wmsion-Salem NC 27 1. 'iV- 1 OX I. E-mail: brubin@
Dr Rubin presented a version of this report at the 17th .'Annual Nevi vvfubmc.edu.

Respiratory Care • Jl ly 2002 Voi 47 No 7 761

Phvsioi or,y of Airway Mucus Clearance

Mucus Flow

Surfactant
Layer

Mucous Gland

Fig. 1 . Ciliary clearance versus cough clearance. Top: Airway epithelium, cilia, and surlactant and mucous layer during normal operation
of cilia. Bottom: Mucus hypersecretion and cough clearance in the presence of ciliary dysfunction.

gel containing water, carbohydrates, proteins, and lipids. -
It is the secretory product of the mucous cells (the goblet
cells of the airway surface epithelium and the submucosal
glands). Mucus is transported from the lower respiratory
tract into the pharynx by air flow and mucociliary clear-
ance. In hinnan large airways, and in many larger species
of mammal, the capacity to secrete mucus in response to a
stimulus seems to lie principally in the glands. However,
at rest, goblet cells may contribute a greater fraction to the
total mucus volume, considering the contribution of distal

airways, where surface mucous cells are found in the ab-
sence of submucosal glands.^

Mucus consists of a superficial gel or mucous layer and
a liquid or periciliary fluid layer that bathes the epithelial
cilia. These 2 layers are separated by a thin layer of sur-
factant (Fig. I ).■* In health, the mucous layer is about 2-5
jum thick in the trachea, and it extends from the bronchi-
oles to the upper airway. The periciliary fluid layer lies
between the cell surface and the mucous layer at a depth
that is just less than the height of a fully extended cilium.

762

Respiratory Care • July 2002 Vol 47 No 7

Pti^sioKKiY o\- Airway Mucus Clearance

Mlicus protects the cpitheliLiiii from tbiviiin nuitcrlal and
trom nuici loss.^ The depth and composition of mucus
depends on secretion from airway glands, goblet cell dis-
charge, and active ion transport across sinface epithelium."

Sputum consists of lower respiratory tract secretions,
nasopharyngeal and oropharyngeal material (including sa-
liva), microorganisms, and cells. When there is mucous
hypersecretion and impaired clearance, abnormal respira-
tory secretions can impair pulmonary function, reduce lung
defenses, and increase the risk of infection and possibly
neoplasia.^

The collection of normal mucus for analysis requires
sampling from endotracheal tubes, bronchial aspirates from
healthy animals or persons, or .secreted material from an-
imal trachea or human bronchial explants.** Commonly the
study of airway secretions consists of examining expecto-
rated sputum, but that material would give only limited
insight into the properties of native, uninfected mucus.

Role of Mucus in Mucociliary Clearance

In health, mucus forms a discrete 5-20 ;u,m layer that
rests at the tips of the cilia. The cilia are bathed in peri-
ciliary fluid that is thought to be an ideal (Newtonian)
liquid of low viscosity. The volume of periciliary fluid
appears to be regulated by surface epithelial cells. '' In the
cartilaginous conducting airways the mucous layer forms
an uninterrupted blanket that prevents airway dehydration
and plays an important role in entrapping and clearing
inhaled particulate matter and cellular debris. There is some
evidence that mucus forms discrete and discontinuous rafts
in smaller airways, and there is little if any mucus in the
terminal airways.*^ Although this has not been verified in
humans, animal studies suggest that mucous layer discon-
tinuity is a function of airway diameter and that the rheo-
logic properties of mucus are also strongly related to air-
way diameter.'" This makes sense, as airtlow-associated
particulate deposition and fluid loss are probably more
important in the larger conducting airways. There is also
the theoretical observation that if mucus secretion volume
and clearance were constant at all anatomic levels, the
proximal airways would rapidly become flooded by the
waves of mucus welling up from the large surface area of
the terminal airways.

Mucus consists primarily of water and is thought to
have only 5-7% solid material, consisting principally of
mucins but also containing secreted antimicrobial proteins
and peptides, phospholipids, and particulate and cellular
debris.' ' Mucins are large glycoproteins that are expressed
in 2 forms: the secreted gel-forming mucins that form the
mucous gel layer and the membrane-tethered mucins
present on the epithelial surface, which may act as cell
surface receptors. Mucin glycoproteins range in size from
several hundred to several thousand kilo-Daltons. Most of

ilie molecular mass of ilie glycoprotein consist of the oli-
gosaccharide sugars that link to the serine- and threonine-
rich protein core called apomucin (Fig. 2). The principal
secreted mucins that form the airway mucous gel are
MUC5AC and MUC5B, the former being primarily a prod-
uct of the surface goblet cells and the latter mostly se-
creted from the submucosal glands.'- The glycosylated
mucin proteins form a gel by linearly polymerizing as
mucin oligomers, resulting in very long and extended mol-
ecules, which form a tangled network. This tangled net-
work produces a gel of fairly low viscosity and elasticity,
permitting it to be easily secreted and cleared by the cilia.
Airway mucus is cleared by 2 principal mechanisms:
mucociliary clearance and airflow interaction (see Fig. 1).
Cough clearance becomes more important as lung disease
de\elops.^ Model studies suggest that mucociliary cleitrance
depends on maintaining the depth of periciliiiry tluid." The
noimal daily volume of respiratory secretion arriving at the
larynx is estimated to be approximately I (J mL.

Mucus Properties

Serous fluid viscosity and depth probably affect muco-
ciliary clearance. If the serous fluid is too viscous the cilia
will not be able to move as well and the decreased ciliary
tip velocity will decrease inucociliary clearance. This prin-
ciple is well established for water propelling cilia, but for
the periciliary fluid in the 2-layer mucociliary system the
serous fluid viscosity is unknown. Active ion transport and
its associated transepithelial water tlux'' are probably im-
portant in modulating serous fluid viscosity. Tran.sepithe-
lial protein fluxes may also contribute to serous fluid vis-
cosity.'"* The efficient transfer of momentum between the
cilia and the mucous layer requires that the cilia firmly
contact the mucus during their forward stroke while min-
imally interacting with it during the return. Mucociliary
clearance will probably also decrease if the serous fluid is
too deep or too shallow.

Mucous factors affecting mucociliary clearance are the
mucus depth and viscoelasticity.^ Although deep mucus
hinders clearance by cilia, it is better suited to clearance by
coughing.'^ Both viscosity and elasticity are essential for
the clearance of airway secretions. Viscosity (energy loss)
is a property of liquids and an ideal (Newtonian) liquid
and can be described strictly in terms of viscosity. An ideal
(Hookian) solid is described entirely by elasticity or en-
ergy storage with an applied stress. A non-Newtonian gel
such as mucus has both viscous and elastic properties (Fig.
3). The elastic component is essential for beating cilia to
transmit kinetic energy to the mucus. Viscosity is also
essential for effective clearance. Patients who have liquid-
like bronchorrhea are unable to clear secretions effectively.
Mucociliary clearance is much more sensitive to high lev-
els of viscositv. although high levels of elasticity may also

Respiratory Care • July 2002 Vol 47 No 7

763

Physioi.ogy of Airway Miiri's Clearance

Oligosaccharide side chain

Serine

Threonine

Fig. 2. Gel-forming airway mucins are large glycoproteins that are secreted to form the mucous gel layer. Most of the molecular mass of
the glycoprotein consist of the oligosaccharide sugars that link to the serine- and threonine-rich protein core called apomucin.

impede eiliary transport."' A balance between these fac-
tors must be maintained (or optimal effect on mucociliary
clearance. '^

Sputum

Expectorated sputum is a sign of disease and indicates
excessive production (hypersecretion) and retention (im-
paired clearance), as occurs in patients with respiratory
infection, bronchitis, asthma, bronchiectasis, and cystic fi-
brosis (CF), When purulent secretions are expectorated
this substance is called sputum.

The characteristics of mucus change with infection and
innammation. Intlammation leads to mucus hypersecre-
tion, ciliary dysfunction, and changes in the composition
and property of airway secretions. Inflammatory cells, par-
ticularly neutrophils, (hat are recruited to the air\\a\ to
combat infection disappear from the airway either through
progranniied cell death (apoptosis) or by necrosis. Ne-
crotic neutiophils release prointlanmiatory mediators thai
damage the epithelium and reciiiit nn)ie inflanniiatory cells.
They also release deoxyribonucleic acid (DNA) and fila-
mentous actin (F-aclin) from the cytt)skelelon. DNA and
F-actin copolynieri/e to form a second rigid nelvsork w ithin
airway secieiions.'^ Neiitrophil-deri\ed myelopero.xidase
imparts a characterisdc green color to intlamed airway
secretions, and thickened and green secretions are usually
described as purulcni.

Cilia

Mucociliary clearance also depends on the function of
the cilia and the interactions between cilia and mucus. The
conducting airways are largely covered by a columnar
pseudo-stratified ciliated epithelium. Each cell has approx-
imately 200 cilia, which propel mucus by beating in a
coordinated, metachronal fashion toward the larynx. Cilia
are motile projections from the polarized surface of the
epithelial cell. The ciliary "motor"' is dri\'en by the dynein-
tubulin interaction (Fig. 4). This adenosine 5 '-triphosphate
(ATP)-dependenl contraction and relaxation are similar to
the actin-m\osin interaction that leads to contraction of
cardiac and skeletal muscle. The coordinated beating of
cilia is internally regulated by the cell; ciliar\' incoordina-
tion is one of the early signs of airway intlammation.

Ciliary factors that affect mucus clearance are mainly
ciliarv amplitude and beat frequencN. which together de-
termine the maximum velocity at the tips of the cilia. In
principle, the faster the cilia beat the faster the mucociliary
clearance, although there are few published data support-
ing this in \ is ().''' Longer cilia should be able to clear
mucus faster because they can generate a greater forward
\elocit\ . A I'lillv extended tracheal cilium is approximately
7 /xm long. In smaller airways the cilia are generally shorter
and fewer in nmiiber than in the large bronchi, and even
though cilia beat frequency may be comparable, the rate of
nuimentum iranst'er to the mucus is proportionately less. In

764

RiiSPiRATORY Cari^ • JuL'i 2002 Vol 47 No 7

Physiology oi- Airway Muc^us Clearance

Strain

Displace rnent

A Ideal Solid

B Ideal Liquid

C: Viscoelastic
Material

Time

Fig. 3. Responses of different types of material to stress and strain,
known as viscoelastic properties. Application of stress or force (Y
axis) over time (X axis) produces the responses sfiown: A. An ideal
or Hookian solid responds to a stress by energy storage or elas-
ticity: tfiis energy is released wfien tfie strain is removed. B. An
ideal or Newtonian liquid responds to stress by deforming contin-
uously with no energy storage; this rate of deformation or energy
loss is viscosity. C. A viscoelastic gel initially stores energy like a
solid but, with continued strain, will then deform more like a liquid.
(From Reference 4, with permission.)

ullraslriic'liii;il iilinoriiialiliL's ot cilia.'' I'hc liiaci ol situs
inversus, chronic bronchiectasis, and male infertility is re-
ferreil to as Kartagcner syndrome, based on a 1933 pub-
lication describing 4 patients Vk-ith this symptom associa-
tion.-- Although persons with PCD often develop recurrent
chest infections and bronchiectasis, the majority of these
people ha\e a normal life expectancy and can be treated by
avoiding aero-irritanls and by receiving antibiotic therapy
for exacerbations of disease. Because this is very different
from the shortened life expectancy of persons with C\\ it
is generally acknowledged that the primary airway defect
in CF is not one of altered mucociliary clearance.

Acute and chronic airway intlammation can also lead to
acquired ciliary dysfunction and to sloughing of the cili-
ated epithelium, with disruption of the mucociliary eleva-
tor. With chronic airway inflammation the cilia can be-
come entangled in the mucus network, making it even
more difficult to clear those secretions. Characteristic ab-
normalities in PCD are discrete frt)m those seen with ac-
quired ciliary dysfunction. In PCD the ultrastructural ab-
normalities in the dynein arms, nexin links, radial spokes,
and ciliary length or orientation are consistently seen in
the majority of cilia. With acquired cilia dysfunction these
abnormalities are seen less commonly, and large fusion
cilia (megacilia) are more the norm.-'

these small airways, mucus clearance is augmented by
autocephalad flow: there is a slightly greater flow during
exhalation than during inhalation, particularly in the distal
lung. Furthermore, there is a small but significant decrease
in resistance across the length of each airway as these
slowly merge and enlarge throughout the bronchial tree.
Together these mechanisms contribute to the progressive
mobilization of distal secretions up the airway toward the
trachea and larynx.

More than 50 congenital abnormalities of ciliary struc-
ture or function have been described as causing primary
ciliary dyskinesia (PCD). Although once termed "immo-
tile cilia syndrome." it is now recognized that many of
these genetic abnormalities produce cilia that are motile
but ineffective at propelling mucus (dyskinetic). Embryo-
logically. normal ciliary function coordinates the rotation
of the thoracic and abdominal viscera, so patients with
PCD have a 50% chance of having mirror-image reversal
of cardiac and abdominal viscera, referred to as situs in-
versus totalis. Because spermatic flagella have the same
ultrastructure as cilia, and flagellar development is gener-
ally under the same genetic control as ciliary development,
most male patients with PCD are infertile. Chronic sinus-
itis and chronically draining ears (chronic otitis media) are
nearly universal in patients with PCD.-" The clinical syn-
drome of PCD was first described in 1901 by Oeri. but in
the mid-1970s Afzelius first showed that PCD was due to

Airway Surfactant

There is increasing evidence that a surfactant phospho-
lipid layer lies between the periciliary fluid layer and the
mucous gel. This surfactant layer has been observed his-
tologically* and is thought to be responsible for effective
spreading of mucus as it is secreted from the submucosal
glands, preservation of the discrete integrity of the peri-
ciliary fluid and the mucous gel, and effective mucociliary
interaction allowing the beating cilia to transmit energy to
the mucous gel without becoming entangled in the mu-
cus.-"* In the course of many inflammatory airway dis-

outer sheath

outer

microtubule —
doublet

radial spoke

centra I
mici'O tubule

Fig. 4. Cross-section of ciliary ultrastructure.

Respiratory Care • July 2002 Vol 47 No 7

765

PiiYsioi.oGY OF Airway Mucus Clearance

eases, secretory plmspholi pases A2 (sPLA2) are secreted,
which can clea\e arachitionic acid from cell membranes,
leading lo ilie generation of ieukotrienes via the lipoxy-
genase pathway and prostaglandins, kinins. and thrombox-
ane \ ia the cyck)o\ygenase pathway. However, these phos-
pholipases also avidly hydrolyze surfactant phospholipids,
including phosphotidal glycerol and dipalmitoyl phospholi-
dylcholine.^^ Surfactant hsdrolysis disrupts this protective
surfactant layer, and it is thought that the lyso-phospho-
lipids generated by the action of phospholipases on sur-
factants are themselves pro-inllammalory and lead to in-
crea.sed mucoadhesion.-'' Airway surfactants are thought
to be derived from the serous cells of submucosal glands
and from the distal airw ays and alveoli. Persons with chronic
intlammatory lung diseases such as CF. chronic bronchi-
tis, and asthma have decreased amounts of bronchial sur-
factant and in many cases increased amounts of airway
lyso-phospholipids. Aerosolized surfactant has been shown
to be effective in promoting mucociliary clearance in pa-
tients with chrt)nic bronchitis and CF. leading to signifi-
cant improvement in pulmonary function.-^

Cough Clearance

In lung diseases characterized by mucus hypersecretion
and impaired airway clearance, the excess mucus is largely
expectorated by coughing. A cough is a complex reflex arc
that begins with the stimulation of an irritant receptor.
Effective cough depends on high gas How and intratho-
racic pressures to enhance mucus removal.-** Cough is in-
effective when respiratory muscles are weak or when mu-
cus adheres to the airway wall. The cough clearability of
mucus simulants increases with the increasing depth of the
mucous layer and is inversely related to mucus elasticity,
cohesivity. and adhesivity.-'' Mucus tenacity, the product
of adhesivity and cohesivity. is a powerful determinant of
cough transportability. -■* Cough transportability is less depen-
dent on viscosity. In fact, preliminaiy studies suggest that for
mucus with similar degrees of tenacity, cough transpoilabil-
ity is increascil by increasing sputum viscosity.

Role of Inflammation

Hypersecretion is usually induced by products of in-
Hammation and infection.'" Inflammatory mediators can
increase mucus secretion as a general response to airway
insult. Changes in the airway microenvironment. such as
pH and osmolarity changes, can also acutely increase se-
cretion and may activate intlammatory mediators that can
also lead to acute increase in secretion." Chronic exposure
to inllammation can lead to hypertrophy and hyperplasia
of both goblet cells and submucosal glanils. When there is
extensive damage to the mucociliary apparatus, these se-

cretions must be cleared by airflow mechanisms, primarily
cough.

For paticiUs with poor nuicociliary clearance and mucus
hypersecretion, airway hygiene can be improved by inter-
ventions that decrease the burden ot airway secretions.
This includes reducing inllammation and infection with
anti-intlanunatory medications and antibiotics, when indi-
cated, or using mucoregulatory medications that reduce
hypersecretion (which are discussed in a subsequent arti-
cle in this issue of RnspiRAroRV Care;).'-

Chest Physical Therapy

Airflow-dependent clearance can also be increased by
moving secretions from the periphery of the lung to more
proximal airways, where greater secretion depth and higher
expiratory air tlow can improve expectoration. This is why
cough is generally incorporated into most chest physical
therapy (CPT) maneuvers."

CPT includes the application of directed cough, forced
expiratory techniques, postural drainage, chest percussion,
clapping, vibration, high-frequency oscillation, and breath-
ing exercises. Mucus transport by expiratory air tlow (in-
cluding cough) is the primary transport mechanism in pa-
tients with pulmonary diseases when mucociliary transport
is damaged.'^ Cough transport is dependent on airflow
velocity, especially peak expiratory flow, which facilitates
mucus detachment from the epithelium. The mucociliary
and mucus-epithelial interaction is most pronounced at the
interface between the 2 surfaces. Detachment can be af-
fected either by airflow forces or by application of phys-
ical therapy techniques such as chest percussion. Once a
critical air tlow is reached (detachment velocity) there is
marked improvement in mucus clearance and ciliary effi-
cacy.

CPT combined with vigorous, directed cough is effec-
tive in clearing the airways of retained secretions." Evi-
dence from studies using inhaled radioaerosol techniques
show that cough alone and cough combined w ith CPT are
equivalent in promoting central airway mucus clearance,
whereas combined techniques are better for accelerating
clearance from the small airways.'''

High expiratory air flow (mucus shearing forces) de-
pends on generation of large positive intrapleural pressure,
best achieved at high lung volumes. High expiratory tlow
can be achieved by a forced expiration, and this appears to
be most efficacious in patients with opimiallv treated air-
tlow obstruction. Dynamic compression of the airways
lakes place during a forced expiration upwards from the
airway equal pressure point. The location and magnitude
of the compression can be varied by expiration force (in-
trapleural pressure) and lung volume (elastic recoil pres-
sure)." For these reasons, breathing exercises are often
combined with CPT.

766

Rhsi^irator'i Care • July 2002 Vol 47 No 7

Physiology oi- Airway Mucus Clearance

Addition ot percussion to ct)n\cntional physiotherapy
has not, in most studies, improved sputum yield or muco-
ciliary clearance, except possibly for CF patients. Postural
(gravity assisted) drainage, as distinct from chest percus-
sion, adds little to the effectiveness of chest percussion and
increases the risk of aspiration from increased gastroesoph-
ageal reflux.'^

Summary

Understanding the physiology of mucus secretion and
clearance cannot only improve our ability to evaluate the
effectiveness of therapeutic interventions; it enhances our
ability to target medications and airway clearance tech-
niques to patients most likely to benefit.

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3. Aikawa T. Shimura S. Sasaki H. Takishima T, Yaegashi H. Taka-
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5. King M. Rubin BK. Mucus physiology and pathophysiology: ther-
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6. Boucher RC. Human airway ion transport. Parts one and two. Am J
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8. Rubin BK. Ramirez O, Zayas JG. Finegan B, King M. Collection and
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9. van As A. Regional variations of mucus clearance in normal and in
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10. Tomkiewicz RP. Albers GM, De Sanctis GT. Ramirez OE. King M.
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1 1. Wanner A. Salathe M. O'Riordan TG. Mucociliary clearance in the
airways. Am J Respir Crit Care Med 1996:154(6 Pt 1 ):1868-1902.

12. Rose MC. Gendler SJ. Airway mucin genes and gene products. In:
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13. Zahm JM. Pierrot D. Vaquez-Girod S. DuvivierC. King M. Puchelle
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14. Govindaraju K. Cowley EA. Eidelmaii 1)11, l.loyd FJK. Analysis of
proteins in micro samples of rat aiiway surface lluid by capillary
electrophoresis. J Chromatography Biomed Sci Applic 1998:705(2):
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15. Bennett WD. Foster WM. Chapman WF. Cough-enhanced mucus
clearance in the normal lung. J AppI Physiol I990;69(5):I670-I675.

16. King M. Rheological requirements for optimal clearance of secre-
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1 7. Puchelle E, Zahm JM, Gir;ird F, Bertrand A, Polu JM, Aug F, Sadoul P.
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18. Tomkiewicz RP, Kishioka C, Freeman J, Rubin BK. DNA and actin
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19. Katz I. Zwas T, Baum GL, Aharonson E, Belfer B. Ciliary beat
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20. Turner JAP, Corkey CWB, Lee JYC, Levison H, Sturgess J, Clinical
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21. Afzelius BA. A human syndrome caused by immotile cilia. .Science
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22. Kartagener M. Zur Patholodie der bronchiektasien: bronchiektasien
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26. Girod S, Galabert C, Lecuire A, Zahm JM, Puchelle E. Phospholipid
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29. King M, Zahm JM, Pierrot D, Vaquez-Girod S, Puchelle E. The role
of mucus gel viscosity, spinnability. and adhesive properties in clear-
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30. King M. Role of mucus viscoelaslicity in cough clearance. Biorheo-
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31. Kishioka C, Okamoto K, Kim JS, Rubin BK. Regulation of secretion
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Physiol 2001:126(2): 163-171.

32. Rubin BK. The pharmacologic approach to airway clearance: mu-
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M. Kim CS, Rodriguez CR, Eldridge MA. Sackner MA. Criteria for
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767

Phvsioi (KiY oi- Airway Mucus Clearance

sion on trachciibronchial clearance In patients with chronic airtlou
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3X.

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Courtesv Health Sciences Libraries. Universitv of Washington

768

Respiratory Carl • Jll^ 2002 Vol 47 No 7

Positioning Versus Postural Drainage

James B Fink MSc RRT FAARC

Introduction

(iravity

Posture iuid Turning

Postural Drainajje
Practice to Evidence
Postural Drainage Procedure

External Manipulation ot the Thorax

Contraindications for Postural Drainage

Hazards/Complications

Role of Exercise

Summary

For the past 70 years positioning and postural drainage have played an important role in increasing
lung \ olumes. perfusion, oxygenation and mobilization of secretions. While gravity is not a primary
mechanism for normal secretion clearance, it plays a major role in depth and pattern of ventilation,
perfusion, and lymphatic drainage. Changing patient position, or turning patients on a regular
basis, is a powerful tool in maintaining lung health in a broad range of patients. In contrast,
postural drainage requires considerable investment of time, and has been shown to have limited
benefit in most patients. Postural drainage has been shown to improve mobilization of secretions in
patients with cystic fibrosis as well as patients who produce, and have difficulty clearing, large
quantities of sputum. The benefits of postural drainage appear technique-dependent, requiring
sufficient drainage time (3 - 15 mini for each position drained. The evidence does not support the
use of vibration and percussion independent of active postural drainage. Exercise (tffers benefit
in secretion clearance, which increases when combined with a program of postural drainage. In
conclusion, routine turning, mobilization and exercise is important to maintain lung health in
all patients, while postural drainage, properly applied, has been shown to improve secretion
clearance in a relatively narrow range of patients with cystic fibrosis and excessive sputum
production. Key Words:, po.stural drainage, secreliiui clearance, chest physical therapy, cystic
fibrosis. IRcspirCare 2()()2;47(7):769-777]

Introduction

Since the 193()s. clinicians have used gravity (by turn-
ins: the patient) to increase lung volumes and oxygenation

James B Fink MSc RRT FAARC is FclUm in Respiralory Science,
Aerogen Incorporated. Mountain View. California
Mr Fink presented a version ol ttiis repori al llie I7tti Annual New
Horizons Symposium at the 47tli International Respiratory Congress. San
Antonio. Texas. December 14. 2(M)1.

Correspondence: James B Fink MSc RRT FAARC. Aerogen Incorpo-
rated. 2071 Stierlin Court. Mountain View CA 94043. E-mail:
jfink@aerogen.com.

and to help mobilize secretions (via postural drainage).
Low lung volume, ineffective cough, ventilation/perfusion
mismatch, and thick secretions are commonly associated
with pulmonary complications.' Though postural drainage
has become synonymous with secretion clearance in pa-
tients who have large volumes of secretions, there is a
greater body of evidence supporting the therapeutic impli-
cations of mobilization and patient positioning for a broader
patient population.' This became evident to the team
charged to develop the American Association for Respi-
ratory Care's Clinical Practice Guideline on Postural Drain-
age. Consequently, that documcni expanded its scope be-
yond postural drainage, to include the therapeutic impact

RiiSPiRATORY Cari-; • Jii.^- 2002 Vol 47 No 7

769

Positioning Versus Postural Drainage

Fig. 1. Changes in perfusion with position change. (From Refer-
ence 1 , with permission.)

of positioning.'' In this paper I explore tlie practice of and
the rationale and evidence for positioning and postural
drainage in secretion clearance.

Gravity

Though postural drainage has been shown to be of clin-
ical benefit for selected patients under very specific cir-
cumstances, gravity is not a primary mechanism for nor-
mal mucus transport in the lung. On the contrary, the
viscosity of the normal mucus blanket is such that it does
not typically flow into gravity-dependent terminal airways.-*

Gravity has a key role in maintaining lung health, with
body position impacting depth and patterns of ventilation.
perfusion, and lymphatic drainage, each of which impact
the ability to effectively clear secretions from the lung and
improve oxygenation. Consequently, mobilizing and reg-
ularly changing the patient's position has long been ac-
cepted as key in management and support of the airway of
the acutely and critically ill patient.

In healthy lung tissue, ventilation is greater in gravity-
dependent areas, with smaller aheoli being more compli-
ant than larger ones. Pulmonary blood flow and lymphatic
circulation are relatively low-pressure systems that are
greatly affected by gravity, so body position affects the
distribution of both blood and lymphatic fluids (Fig. 1;.

Posture and Turning

Turning the patient from supine to lateral or prone po-
sition (Fig. 2) results in a net increase in lung volumes
(functional residual capacity) and improved oxygenation.^
As the patient is turned, the weight of the mediastinum,
lung tissue, and abdominal contents tends to compress the
gravity-dependent lung, while the superior lung is pulled
open to a larger volume, resulting in a net increase in lung
volume. When areas of atelectatic lung are mo\ed to su-
perior position, the weight of the mediastinum and lung
pulls on elastic tissue in the lung, expanding the airways
and alveoli. As the patient is turned, blood, lymphatic
fluid, and extravascular water migrate to gra\ity-depen-
dent areas of the lung. Consequently, in the superior lung

Fig. 2. Common patient positions. A. Supine. B. Prone. C. Fowl-
er's. D. Semi-Fowler's. E. Side-lying. F. Supported prone. (From
Reference 1 , with permission.)

there is reduced perfusion, increased forces expanding the
airway, and reduced tidal \entilation secondary to the in-
creased size of the airways. The strategy of placing the
good lung dow 11 promotes good ventilation matching areas
ot perfusion, w hile the superior lung is expanded and per-
fusion is reduced.

770

Ri-spiRATORY Care • Jul^' 2(X)2 Vol 47 No 7

PosmoNiNCi Vi;rsus Postiirai Drainagh

o
>

7.00 n

6.00

5 00

4,00

3.00

2.00 -

1 00 -

0.00

Sitting

Standing

inspiratory
Capacity

Expiratory

Reserve

Volume

Residual
Volume

Supine

Right Lateral Left Lateral Trendelenburg

Fig. 3. Changes in lung volumes with position. Top row of bars represents inspiratory capacity. Middle row of bars represents expiratory
reserve volume. Bottom row of bars represents residual volume. Function residual capacity (expiratory reserve volume plus residual volume)
IS reduced in the supine position, with net increases in either lateral position. Note further reduction in functional residual capacity in
Trendelenburg position. (From Reference 1 . with permission.)

Douglas et al demonstrated that the supported prone
position (supporting the patient at the hips and chest, al-
lowing the abdominal contents to hang freely) results in
larger lung volumes, with blood oxygen saturation im-
provement similar to that obtained with application of con-
tinuous positive airway pressure in chronic obstructive pul-
monary disease patients in acute respiratory failure.''
Consequently, use of the prone position, even without sup-
port, has been shown to offer important benefits in oxy-
genation (Fig. 3).''-'^

In critical care and postoperative situations, where atel-
ectasis is a major complication, factors such as pain and
the risk of dislodging tubes, monitor leads, and lines make
it very tempting to leave the patient supine for a prolonged
period. However, the longer a patient remains supine the
greater the chance that lung volumes will be reduced and
that secretions, aspirated gastric contents, and extravascu-
lar interstitial fluids will pool in gravity-dependent areas.'"

Turning the patient is a primary technique for lung ex-
pansion. Patients should be encouraged to turn, or be turned,
at least every 2 hours, while awake. Early mobilization of
patients (who can safely get out of bed) is a superb exam-
ple of optimal lung expansion therapy, with minimal ad-
ditional cost.'

Just as changes in body position can improve the match-
ing of ventilation with perfusion in the dependent lung.
turning can have deleterious effects, so each change in
position should be evaluated for patient tolerance. When
the less-healthy lung is in the dependent position, areas of
decrea.sed \entilation ha\e increased perfusion, resulting

in poor oxygenation and potential heinodynamic instabil-
ity. When turning unstable or critically ill patients, oxygen
saturation, dyspnea, and blood pressure should be moni-
tored to determine patient respon.se and tolerance.

In unilateral lung disease, placing the healthier lung
down initially improves oxygenation. However, over time
the gravity-dependent intercellular fluids, lymphatic flu-
ids, and secretions migrate, transforming the healthier lung
into the less-healthy lung. Consequently, turning the pa-
tient every I or 2 hours, so that the less-healthy lung is
down, even for short periods, will help to maintain the
integrity of the good lung.

Rotating beds that continuously turn the patient from
side to side are associated with fewer pulmonary compli-
cations and a lower incidence of pulled and disconnected
lines. Though the studies have been encouraging, more
randoiTiized controlled studies are necessary to determine
whether these expensive support devices are better overall
than the standard practice of periodically turning the patient.

Postural Drainage
F'ractice to F3\idt'nce

In a recent reviev\ of the evidence supporting the prac-
tice of secretion clearance techniques. Hess reported a
dearth of high-level evidence to support any secretion clear-
ance technique.'" A brief history of postural drainage may
offer some insights as to how early anecdotal observations

Respiratory Carii • Jt ly 2002 Vol 47 No 7

771

Positioning Versus Pcxsturak Drainage

have led to therapeutic interventions that represent a sub-
stantial component of respiratory care practice.

The practice of postural drainage began with the treat-
ment of surgical patients, prior to the availability of anti-
biotics. Bronchiectasis was a common disease, and when
patients with bronchiectasis required lung resection to treat
tuberculosis, surgeons observed thick secretions infiltrat-
ing the fresh incisions and a high incidence of postopera-
tive complications. Tipping was used to drain secretions
from the bronchiectatic airways adjacent to the resected
area and was associated with fewer postoperative infec-
tions.

The earliest text I am aware of on postural drainage was
published in 1956. It is a 63-page monograph by E Wini-
fred Thacker, Superintendent Physiotherapist, at Harefield
Hospital, United Kingdom, entitled Postural Drainage and
Respiratory Control." which identified many of the ra-
tionales for and practical limitations of chest physical ther-
apy (CPT), as shown in the following excerpts:

Postural drainage must be regarded as a period of
concentrated coughing and basal breathing, during
which time every effort is made to clear the lungs of
secretions. To achieve this, determined enthusiasm
on the part of the therapist as well as accurate pos-
turing, good diaphragmatic breathing and correct
coughing will produce the best results.

Thus, breathing exercises and controlled cough are in-
tegral with postural drainage.

To those who do not appreciate the necessity of
postural drainage in the presence of lung suppura-
tion we give the following analogy. The infected
area is like a narrow necked bottle filled w ith thick
oil. The ordinary cough resembles hitting the base
of the bottle and jerking some of the oil out. The
answer is to invert the bottle and leave it with the
neck hanging down: this can only be done if the
bottle is placed in the proper position. A further aid
to ejection is concentrated localized breathing ex-
ercises, particularly if carried out during postural
drainage.

That analogy was later corrupted into the "ketchup bot-
tle analogy" of hitting the bottle to mobilize the contents.
But, on the contrary, the key concepts of postural drainage
are posture, time. hreathinK. and cough: percussion and
vibration are only minor components of the therapy.

Ideally patients w ith a quantity of sputum should tip
4 times daily for al least half an hour at each ses-
sion, or an hour if there are 2 or more areas to drain.

Based on this seminal text, treatment was typically 1 or
2 positions per session, lasting from 30-60 min. Over the
years, many institutions have redefined CPT to include up
to 12 positions, for as little as 15 min, v\ith no e\idcnce to
sujiport the change in practice.

Too often it is found that ""postural drainage"' con-
sists only of raising the foot of the bed or tipping
the patient once or twice a day. . . posture must be
used over prolonged periods.

Similarly, many clinicians have substituted percussion
and vibration for proper positioning and appropriate drain-
age times.

Forty years later, there has been little high-level evi-
dence introduced to support the clinical benefit of postural
drainage and the evolution of practice and clinical appli-
cations from that first early monograph.

Postural drainage is the gold standard to which all other
bronchial hygiene techniques are compared. Although tech-
niques such as directed cough, active cycle of breathing,
forced expiratory technique, positive airway pressure, and
high-frequency oscillation of the airway and chest wall
more directly support normal mucus transport mechanisms
than does postural drainage, they have, at best, equivalent
efficacy.

Thomas et al conducted a meta-analysis'- of the effi-
cacy of physical therapy modalities (eg, positive expira-
tory pressure, forced expiratory technique, exercise, auto-
genic drainage, and standard CPT) for clearing bronchial
secretions with cystic fibrosis patients. They reviewed 456
citations from 1966 to 1993. which yielded 35 trials that
met inclusion criteria. Standard physical therapy (postural
drainage with percussion and vibration) resulted in signif-
icantly greater expectoration than no treatment (effect size
of 0.61 SD units, p < 0.0001). CPT with exercise was
associated with better FEV, than CPT alone (p = 0.04).
They found no other differences between physical therapy
modalities. The majority of studies suffered from small
sample size, short duration, and inadequate descriptions of
the treatments being tested. In addition, the end points are
all too often indirect surrogates for improved airway clear-
ance. The 3 rnost common variables measured have been
changes in pulmonary function, clearance of radiolabeled
aerosol, and volume of sputum. In the long run. the vol-
ume of sputum is among the easiest to perform and the
least meaningful. Quantitation of difficulty in expectora-
tion (eg. with a visual analog scale) has substantial impli-
cations tor patient quality of life. Other important vari-
ables include number of missed days of work or school,
frequency of exacerbations (as evidenced by number of
emergency visits), hospital admissions, and hospital length
of stay.

772

RESPikAroRY Care • July 2002 Vol 47 No 7

Positioning Vi;rsiis Postural Drainagh

Fig. 4. Common positions for chest physiotherapy. Drainage for (A) anterior segments of upper lobes. (B) superior and inferior segments
of lingula. (C) anterior basal segment of lower lobe, (D) lateral basal segment of lower lobe, (E) superior segment of lower lobe, (F) posterior
basal segments of lower lobes, (G) lateral and medial segments of right middle lobe, (H) apical segment of upper lobe, (I) posterior segment
of upper lobe. (From Reference 2, with permission.)

Respiratory Care • July 2002 Vol 47 No 7

773

Positioning Versus Postukai. Drainage

Table 1. Proucdurc lor Posilioning

Turning (Repositioning j/Mobility

1. Explain lo the patient that the reason lor Ireiiiient position
changes and niohility is lo promote lung expansion anj to
improve blood oxygenation.

2. Encourage the patient lo turn independently and/or assist him or
her to change position as necessary. Optimal positions for lung
expansion and secretion mobilization are oblique side-lying with
the bed at any degree of inclination as tolerated by the patient,
and prone. Sitting, dangling at the bedside, and ambulation are
also effective in promoting lung expansion and secretion
mobilization.

3. Repositioning frequency is determined in part by assessment of
tissue tolerance. The reddened area marking the points of pressure
should disappear within 30 min after the patient is repositioned. If
the reddened area remains longer than 30 min the turning frequency
should be increased and/or the support suiface changed.

4. Pillows and other positioning devices should be used to keep
bony prominences from direct contact with one another and to
prop up or help support the patient in the desired position.

5. With each change in position, assess the patient for increased
dyspnea, decreased oxygen .saturation, and discomfort.

6. Even when positions are poorly tolerated, position changes for as
little as 5 min serve to promote redistribution of ventilation,
blood perfusion, and lymphatic How.

7. Document patient response in the patient record.

^■Ui»' —

Fig. 5. Percussion devices and techniques. A. Manual clapping. B.
Manual clapping devices. C. Mechanical percussor. (From Refer-
ence 1, with permission.)

Table 2. Procedure for Postural Drainage

Equipment

• Bed or table that can assume a range ol positions, from
Trendelenburg to reverse Trendelenburg position

• Pillows for supporting patient while in position

• Light towel for covering area of chest during percussion

• Tissues and/or basin for collecting expectorated sputum

• Suction equipment for patients unable to clear own secretions

• Gloves, goggles, gown, and mask

• Optional; hand-held or mechanical percussor or vibrator

1. Instruct patient that postural drainage therapy is used to mobilize
secretions and that regular use can reduce deterioration of lung
function and acute exacerbations. Patients should also be taught to
perform active cycle of breathing technique and huff.

Instruct the patient to:

(a) Assume each position with niininium ol discomlort. and to
maintain each position for ?-IO mm.

(b) Take slow deep breaths and to use thoracic expansion, forced
expirations, and huff in each position.

(c) While draining a position, percussion or vibration may be
applied over the affected area of the lung. Manual vibration
may be applied on exhalation.

2. Modify positions to optimize patient tolerance and comfort (ie.
reduce angle of head-down lilt while draining posterior basal
segments).

3. Evaluate the patient or caregiver for his or her ability lo self-
adininister. Observe patient self-administer on several occasions to
assure proper uncoached technique prior lo allowing patient to sell-
administer without supervision.

Though most protocols are compared against standard
postural drainage therapy, it is clear that inost of the avail-
able alternatives are comparable in terms of benetlt to the
patient. The question appears to be less one of "will it
work?" than "will the patient use it?" If the patient per-
ceives benefit, then the chance of adherence is greatly
increased (Table I ).

Fig. 6. Manual vibration technique. (From Reference 40, with per-
mission.)

774

RispiR ATORY Care • ivL\ 2002 Vol 47 No 7

PosirioNiNCi Vi:rsus Postural Drainage

Postural Drainase Procedure

Posiuial drainage consists of positioning the patient so
that secretions u ill drain from specific segments and lohes
of the lung tow ard grav ity-dependent central airways, u here
they can be more readily removed with cough or mechan-
ical aspiration. This is accomplished by positioning the
patient so that the affected segments of the lung are supe-
rior to the carina, with each position maintained for at least
3-15 min. Nine to 12 positions are needed to drain all
areas of the lungs, requiring at least 1 hour for a complete
session (Fig. 4 and Table 2).-'

There is evidence that postural drainage is effective in
treating acute and stable cystic fibrosis, bronchiectasis,
and other conditions characterized by mucus hypersecre-
tion or difficulty clearing secretions." Postural drainage
has been found to ha\e little or no effect in conditions
associated with scant secretions (eg, viral pneumonia, post-
operative coronary artery bypass). Consequently, the indi-
cations for postural drainage are largely limited to patients
with cystic fibrosis'-*--- or bronchiectasis"-^ and patients
VK ho produce > 30 mL of secretions per day and who have
difficulty clearing secretions.--'' Similarly, studies in
which indi\ idual positions were drained for less than 3-10
min ha\ e shown no advantage over controls.

Sputum production of < 25 niL/day is insufficient to
justify the application of postural drainage thera-
py 12.20,30.34 -3is Some patients have productive coughs, with
sputum production of 15-30 mL/day (occasionally as high
as 70-100 mL/day) without use of postural drainage. If
postural drainage does not increase sputum production in
a patient who produces > 30 mL/day witht)ut postural
drainage, the continued use of postural drainage is not
indicated. Improved ease of clearing secretions during and
immediately after postural drainage supports continuation
of the therapy.

External Manipulation of the Thorax

Percussion therapy (not to be confused with high-fre-
quency oscillation of the chest wall) is a technique of
rapidly clapping, cupping, or striking the external thorax
directly over the lung segment being drained. This can be
accomplished with cupped hands or mechanical devices
(Fig. 5). Theoretically, percussion assists secretion mobi-
lization by shaking the secretions loose, like shaking
ketchup from a bottle. Though there is little evidence that
percussion improves mobilization of secretions during pos-
tural drainage, there is no evidence that percussion alone,
w ithout patient positioning, is of any \ alue. Manual meth-
ods offer no advantage over mechanical meth-
ods I ''■-IM- '"'-'"

Vibrating the chest wall over the draining area, using
a fine tremorous action during expiration, has also been

advocated to assist secretion mobilization during
postural drainage (Fig. 6). Evidence suggesting that vi-
bration for up to an hour can increase movement of
secretions does not support the clinical efficacy of this
procedure. I '•!■'■='•'•*■->'■'■'"•••" -*■* Percussion and vibration
appear to be relatively ineffective-*- -^^ and do not seem
to add to the effectiveness of the combination of cough-
ing, breathing exercises, and postural drainage, •*■*
whereas forced expiratory technique, even without pos-
tural drainage, enhances tracheobronchial clearance. ■•''

Unfortunately, some clinicians interpret an order for
CPT to mean percussion without use of postural drainage
positions. In light of the absence of evidence (or even
anecdote) that percussion without positioning is of any
benefit to the patient, that practice would seem to be clin-
ically inappropriate.

Whether or not vibration or percussion is effective for
mobilization of secretions, the application of these proce-
dures as an adjunct to postural drainage, especially with
mechanical vibrators and percussors, often feels good to
the patient, which is the most convincing reason to con-
sider applying the techniques.

Contraindications for Postural Drainage

Head-down or Trendelenburg position impacts hemo-
dynamics and the interaction of physical forces between
the thorax and the abdomen. Trendelenburg position should
be avoided in patients whose intracranial pressure (eg,
neurosurgery, aneurysm, eye surgery) is elevated > 20
mm Hg-*^ -*' or who have uncontrolled hypertension or gross
hemoptysis related to recent surgery for lung carcinoma or
radiation therapy.^*" Shifting of abdominal and thoracic
contents with gravity in Trendelenburg may be deleterious
in patients at risk for aspiration with uncontrolled airway,
distended abdomen, or recent esophageal surgery. Reverse
Trendelenburg may be hazardous for patients with hypo-
tension and those receiving vasoactive medications.

Percussion involves substantial risk but little benefit. It
is contraindicated in patients with suspected pulmonary
tuberculosis or resectable tumors of the thorax or neck,
because the percussion might shake loose bacteria or can-
cer cells that could transport to other parts of the body.
Small lipomas and sebaceous cysts are not contraindica-
tions for percussion. Percussion can increase wheezing,
airway closure, and dyspnea. Lung contusion and coagu-
lopathies may be aggravated by percussion. Relative con-
traindications are osteoporosis and osteomyelitis of the
ribs or complaints of chest pain.'

Hazards/Complications

Postural drainage therapy has been associated with hy-
poxemia, bronchospasm. acute hypotension, increased in-

Respirator'i- Care • Jll^- 2002 Vol 47 No 7

775

PoSITIONINC; VkRSUS POSTI'RAI, DRAINAGE

tracranial pressure, pulmonary hemorrhage (hemoptysis),
pain/injury to the tissue, and Nomitins:. with risk of aspi-
ration.-'*' To minimize risiv ol \onnlinij and aspiration for
patients receiving tube feedings, slop feeding I hour prior
to and during therapy. Simiiariv. therapy should be per-
formed either before meals or more than 1 hour after meals.
Bronchodilators are commonly administered prior to pos-
tural drainage therapy to patients with a history of bron-
chospasm.

Conditions that can be exacerbated by percussion or
vibration to the thorax include burns, open wounds, skin
infections, recent skin grafts, subcutaneous emphysema,
recently placed pacemaker, or recent epidural spinal infu-
sion of anesthesia of spinal type. Percussion and vibration
are difficult for patients to apply without assistance.

Postural drainage therapy is time-intensive, requiring
30-60 min 3-4 times each day. with special equipment
such as a tilt table. This time-commitment is a major ob-
stacle to prescription adherence by the patient. Less ob-
trusive and time-consuming alternative therapies would be
of great value, if they are clinically equivalent.

Role of Exercise

Baldwin et aH'' evaluated the effect of exercise plus
CPT on sputuiTi expectoration and lung function in 8 adult
subjects with cystic fibrosis. Exercise alone increased spu-
tum production 3-fold, compared to rest. In a direct com-
parison of exercise with physiotherapy, Sahl et al showed
that exercise increa.sed sputum production, but not as much
as physiotherapy.'^" Zach et al'^' suggested that exercise
could be substituted for physiotherapy without deteriora-
tion in most patients, Baldwin et aP'* found that exercise as
an adjunct to physiotherapy was more effective than phys-
iotherapy alone, whereas Bilton et al'^- found no differ-
ence. Exercise appears to augment bronchial hygiene and
should be encouraged, as tolerated: however, it should not
substitute for other bronchial hygiene regimens.

Summary

Although gravity is a minor factor in normal mobiliza-
tion of secretions, it has major influence in factors such as
lung volumes and ventilation patterns that can impact cough
effectiveness in a broad range of acutely ill and bed-ridden
patients. These benefits can accrue with minimal effort
through routine turning and mobilization protocols. Pos-
tural drainage has long been considered the gold standard
for secretion clearance, but has only been proven to benefit
patients with diseases such as CF and bronchiectasis. Tech-
niques such as percussion and vibration, which appear to
be active, have not been shown to significantly improve
secretion clearance during drainage, and have no evidence
supporting their use outside ol drainage. In contrast, breath-

ing exercises and directed coughing are important compo-
nents of effective postural drainage therapv.

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98(6):1336-1340.

47. Oldenburg FA Jr. Dolovich MD. Montgomery JM. Newhouse MT.
Effects of postural drainage, exercise and cough on mucus clearance
in chronic bronchitis. Am Rev Respir Dis 1979;12n(4):739-745.

48. Tyler ML. Complications of positioning and chest physiotherapy.
Respir Care I982;27(4i:458^66.

49. Baldwin DR. Hill AL. Peckham DG. Knox AJ. Effect of addition of ex-
ercise to chest physiotherapy on sputum expectoration and lung lunction
in adults with cystic fibrosis. Respir Med 1994;8S( 1 1:49-53.

50. Sahl W, Bilton D. Dodd M. Webb AK. Effect of exercise and phys-
iotherapy in aiding sputum expectoration in adults with cystic fibro-
sis. Thorax I989;44(I2):I006-1008.

51. Zach MS. Purrer B. Oberwaldner B. Effect of swimming on forced
expiration and sputum clearance in cystic fibrosis. Lancet 1981;
2(8257):I20I-I203.

52. Bilton D. Dodd ME. Abbott JV. Webb AK. The benefits of exercise
combined with physiotherapy in the treatment of adults with cystic
fibrosis. Respir Med l9y2;86(6):.S07-51 1.

Respiratory Carl • iv\,\ 2002 Vol 47 No 7

777

Airway Physiology, Autogenic Drainage,
and Active Cycle of Breathing

Craig D Lapin MD

Introduction
Airway Physiology

Equal Pressure Point

Collateral Ventilation
Autogenic Drainage
Active Cycle of Breathing Technique
Evidence-Based Medicine
Summary

Airway clearance techniques are used to aid in mucus clearance in a variety of disease states.
Autogenic drainage and active-cycle-of-breathing technique are 2 such modalities that rely heavily
on basic airway physiology to enhance clearance. In this review I discuss the equal pressure point,
huffing, and asynchronous and collateral ventilation, and review the literature and theory regard-
ing autogenic drainage and active cycle of breathing. Selection of airway clearance techniques is
discussed in the light of evidence-based medicine. Key wards: airway physiology, ainvay clearance
techniques, chest physical therapy, equal pressure point, huff, autogenic drainage, active cycle of breath-
ing technique. [Respir Care 2002;47(7):778-785]

Introduction

Production and clearance of airway secretions occurs
throughout the respiratory tract on a daily, minute-by-
minute basis. Under normal conditions the volume and
viscoelastic properties of the secretions produced are eas-
ily managed by the cilia, regular respiration, and, when
necessary, the occasional cough. In many disease states,
however, changes in mucus characteristics or quantity, or
changes in lung physiology overwhelm the normal muco-
ciliary escalator.

Craig D l^pin MD is affiliated with tine Division of Pediatric Pulmonan.'
Medicine, Connecticut Children's Medical Center, Hartford. Connecticut.

Dr I.apin presented a version of this report at the 17th .\nnual New
Horizons Symposium at the 47th International Respiratory Congress. San
Antonio. Texas. December 14. 2001.

Correspondence: Craig D l.apm MD. Division ol Pediatric Pulnionar\
Medicine. Connecticut Children's Medical Center. 282 Washington Street.
Hartford CT 06106.

Over the past 35 years a multitude of airway clearance
techniques have been developed, introduced, refined, re-
.searched, and used in patient populations, from asthma to
atelectasis, from cystic fibrosis (CF) to chronic obstructive
pulmonary disease (COPD), to help assist normal mucus clear-
ance mechanisms. Chest physical therapy has become almost
synonymous with postural drainage and percussion (PD&P).
Newer modalities include autogenic drainage (AD), active
cycle of breathing technique (ACBT), positive expiratory pres-
sure methods, high-frequency airway oscillation (flutter),
high-frequency chest wall oscillation {The Vest), intrapulmo-
nai7 percussive ventilation (IPV), and mechanical insuffla-
tion-exsuftlation (the "iii-exsufllator""!. The impetus tor this
explosion in airway clearance options, as with any medical
treatment, has been the continued search for improved effi-
cacy and tidherence to a presciibed therap).

Mucus is moved by 3 mechanisms. First, slug flow de-
scribes the means by which a semi-solid mucus plug ob-
structing or partially obstructing an airway can be pushed
from behind by air tlow. Second, annular flow describes
miictis mo\ ing tiloiig the v\alls of the airw a> . either being
pulled aloTig by expiratory air tlow or transported by cilia.

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Respirator'*- Care • July 2002 Voi. 47 No 7

Airway Pii\.sK)i(Kiv. Aukkii.nk DkAiNACih, anu Activi: C^ci.i; oi Bklahiing

Third. ini.M JIdw describes iicriisoli/L'd mucus dial is ex-
haled as suspended droplets. Slug and annular flow ac-
count for the majority of airway secretion clearance.

There are only 2 o\er-riding physical principles to air-
way clearance techniques: first, there must be airtlow; and.
second, for the patient to have air flow . the patient must he
able to get air behind the mucus.

Airway Physiology

All airway clearance techniques, lo be errecli\e. must
inleracl with liuig ph\siology to enhance secretion mo\e-
ment. A clear and thorough luidcrsianding ol a few phys-
iologic concepts and hypotheses will help the respiratory
practitioner understand how each airway clearance tech-
nique works. Without knowledge or consideration of these
principles, someone might suggest, for example, that hav-
ing a patient mentally visualizing increased secretion clear-
ance w hile w atching television will impro\ e secretion clear-
ance! Not only can know ledge of the basis of these therapies
help understand why they work: it may also aid in decid-
ing which modality to use for which disease state.

EQUAL

PRESSURE

POINT

Ppl = 10 cmH2 0

PstI = 10 cmH20

Palv = 20cmH2O

Fig. 1 . The equal pressure point concept. Pressure is dissipated as
air flows towards the mouth. The point at which the pressures
inside and outside the wall are the same is the equal pressure
point (EPP). Downstream (toward the mouth) from the EPP, the
airway is compressed because the pressure surrounding it is greater
than the pressure in the lumen. Pp, ^ expiratory force. P^,, = static
elastic recoil. P^,^ - intraluminal (alveoloar) pressure. (From Ref-
erence 1, with permission.)

Equal Pressure Point

The equal pressure point (EPP) concept is integral to
understanding the airtlow limitation that is so important in
many aspects of pulmonary medicine, from pulmonary
function testing (PPT) to airway clearance techniques. The
point at which the intraluminal and extraluminal pressures
are equal is the EPP (Fig. 1 ). Beyiind that point (ie. toward
the mouth), the external pressure around the airway is
greater than the pressure within it. and the airway com-
presses, which limits (low . During a forced exhalation the
pressure in the airways (intraluminal) decreases from the
peripheral airw ays to the mouth, because of frictional pres-
sure loss and convecti\e acceleration pressure loss." The
pressure decreases because of the movement of air from
the periphery (with a cumulatisely large cross-sectional
airway area) centrally (with gradual cumulative cross-sec-
tional area decreasing). During the exhalation the extralu-
minal (pleural) pressure remains relatively constant: the
intraluminal pressure gradually decreases. Thus there is a
wave of equal pressure points moving deeper (more pe-
ripherally) into the airways as exhalation proceeds and
intraluminal pressures fall.

The site of the EPP is determined by the amount ol
expiratory force and the elastic recoil (see Fig. I ). A higher
expiratory force shifts the EPP peripherally (tovvard the

alveoli). Likewise, if the forced exhalation is initiated at a
lower lung volume, the pressure from the static elastic
recoil will be less, as will the intraluminal pressure, and
the resulting EPP will again be more peripheral. Initiated
at normal lung volumes or with normal-to-high expiratory
pressure, the EPP is estimated to lie at the carina or larger
bronchi.^ which are reinforced by cartilage and thus resist
collapse.

Cough is the body's natural backup inechanism for air-
way clearance. Usually a deeper inspiration is followed by
closure of the glottis, high intrapulmonary pressures are
built up behind the glottis, and when the glottis opens,
supra-maximal, expiratory, turbulent air Hows (flow tran-
sients) are generated. The EPP plays an extremely impor-
tant role in the effectiveness of cough, because a substan-
tial jump in airflow selocity occurs at points of narrow ing
(choke points). High linear airflow velocity provides the
turbulent How, high shearing forces at the airway walls,
and high kinetic energy that move secretions cephalad —
analogous to the effect of a strong wind over a body of
water: and the waves and spray generated are visibly sim-
ilar. Physiologically, consider that the amount of air flow-
ing past a choke point at any instant is equal to that flow-
ing in less constricted regions. The only way it can be
equal under such conditions is it ilie linear gas velocity is
L'reater.

Respiratory Carh • ivi\ 2002 Vol 47 No 7

779

Airway Physiology, Autogenic Drainage, and Active Cycle of Breathing

Maximum forced
flow-volume loop 1

Volume (L)

fVlaximum forced
flow-volume loop 2

Volume (L)

Fig. 2. Flow-volume curves comparing flow-transients from voluntary cough (left) and huff (nght). relative to the subject's maximum forced
flow-volume loop.

Mathematically, if flow is equal and cross-sectional
Area-, is smaller (ie. more narrow) than Area,, and

Flow
Volume

Volume/Second
Area X Length

then

Flow =

Velocity =

(Area X Distance )/Second
Distance/Time

and

Flow

Area, X Velocity i = Areai X Velocity^

then Velocity, must be greater than Velocity,.

Another means to produce supra-maximal air flow and
high linear velocities is by huff (Fig. 2). Huff is a forced
expiratory maneuver, usually initiated from mid-to-low
lung volumes and is performed with an open glottis.'* Again,
the EPP augments the linear velocities occurring with this
maneuver. Although a huff does not produce the same
magnitude of tlow transients as a cough, it has several
other advantages. A cough is generated by the build-up of
extremely high intraluminal and cxtraluminai pressures, so
with cough there is more potential for substantial airway
collapse at the EPP. especially if airway stability is lack-
ing. Cartilaginous support decreases from trachea and larger
bronchi to the smaller bronchi, and probably is minimal
within bronchioles. Although smooth muscle may aid in
maintaining the patency of the smaller airways, a cough
may compress those airways too much to allow effective
clearance.'^ Another mechanism that impairs cough clear-

ance is dynamic collapse, which may occur in disease
states that have increased airways compliance (eg, CF,
COPD). Even the larger airways may become unstable if
frequent coughing has damaged the cartilage (eg, chronic
bronchitis, CF).

Coughing is mostly reflexive (although it can be "di-
rected"), so cough does not allow as much conscious con-
trol of starting lung volume or pressures developed. Thus,
huff has the advantage that the patient and therapist can
adjust the huff to balance the potential of airway collapse
against expiratory force. Huff can also be started at various
lung volumes, thus allowing the shift of the EPP into more
peripheral airways and maximizing air tlow there.

But the question arises whether the flows generated by
a huff or by moving the EPP are sufficient to promote
mucus clearance. Studies have shown that mucus can be
mobilized with expiratory airflow velocities of 1.0-2.5
m/s for annular flow or > 2.5 m/s for mist flow ." Mucus
transport can even occur from the flow of tidal breathing,
in some circumstances.' Bennett and Zeman** detennined
that airway clearance with huff was faster than control and
similar to that generated by voluntary cough.

For mucus clearance to occur, air must be able to get
behind (ie. peripheral to) the mucus. Even in normal lungs,
time constants vary among lung regions, and asynchro-
nous ventilation (ie, differences in lung filling) occurs sec-
ondary to regional and stratified inhomogeneity.'' Mucus
obstruction (partial or complete) in disease states may in-
crease the inhomogeneity.'" substantially impairing the
ability to get air past mucus obstructions. Many airway
clearance techniques include a breath-hold to compensate
for asynchrt)nous ventilation.

Inspiration dilates airways as negative pleural pressure
causes the luniis to inflate, causins a transient decrease in

780

Respiratory Care • July 2002 Vol 47 No 7

Airway PHVsioi.otiv, Autogknic Drainage, and Activk Cyci.k ui- Brhaihing

llow

Fig. 3. Airway diameter increases during inspiration (left), which
decreases resistance and therefore increases flow. Airway diam-
eter decreases during expiration, which increases resistance and
therefore decreases flow.

the resistance to airway flow (relative to exlialalioii) (Fig.
3), which aids in getting air behind the mucus, interde-
pendence between adjacent parenchymal lung units occurs
because of the elasticity of the surrounding interstitium,' '
and also occurs between the lungs and chest wall.'- The
effect of both help to preserve uniform \entilation distri-
bution.

Collateral \ entilation

Collateral ventilation channels (the canals of Lambert,
channels of Martin, and pores of Kohn) (Fig. 4) between
adjacent contiguous lobules and adjacent alveoli are prob-
ably not important in normal ventilation, but may be im-
portant when there is airway obstruction." '"*

The major physiologic factors in collateral ventilation
are collateral resistance and respiratory frequency relative
to regional time constants. Increasing lung volume sub-
stantially decreases collateral resistance, probably as a re-
sult of the outward forces of interdependence on the ob-
structed region and increased segmental volume.'^ At an
increased respiratory rate and flow, an unobstructed region
will till more rapidly than a partially or completely ob-
structed one. because the pressure drop across the obstruc-
tion is less and flow is less impeded. As the time constants
of the connected pathways shift, the more slowly ventilat-
ing unit will receive part of its inspired volume via col-
lateral channels from the more rapidly ventilating unit (this
is known as pciidelluft flow). Lower respiratory frequency

Interbronchiolar channels of Martin

Bronchiolar-alveolar
channels of Lambert

Alveolar pores of Kohn

Fig. 4. Collateral ventilation channels.

and larger tidal \oluiiie should increase the degree of col-
lateral ventilation.'"

Autogenic Drainage

Autogenic drainage was conceived by Jean Chevaillier
in Belgium in 1967 at the Zeepreventorium De Haan. an
institution dedicated to the care of difficult asthma. Care-
ful t)bservation had suggested that more mucus was cleared
during breathing exercises, playing, laughing, forced ex-
piratory maneuvers, or even sleep than during postural
drainage, percussion, or pursed-lip breathing (Jean Chev-
aillier, Physiotherapy Departement, Zeepreventorium De
Haan, Belgium, personal communication, 1990). The un-
derlying concept of AD is to achieve high expiratory flows
in various generations of bronchi, by controlled breathing,
but to avoid coughing or substantial airway closure.''''*
The AD technique requires feedback to the patient until
the patient attunes to the auditory and chest sensations
associated with mucus clearance.

Autogenic drainage is initiated with a slow inspiration
through the nose, followed by a 2-3-second breath-hold.
Breathing slowly through the nose humidifies and warms
the inspired air and minimizes the air tlow turbulence,
which helps prevent coughing. The breath-hold and slow
inspiration provide optimal filling of obstructed lung seg-
ments while avoiding excessive intrapleural pressure
(which could compress unstable airways). Phase 1 (periph-
eral "unsticking" of mucus) is accomplished by having the
patient exhale, with an open glottis, down into expiratory
reserve volume (ERV). but not to residual volume. This is
similar to steaming a mirror or eyeglasses. The patient
then breathes with inhalations of mid-tidal volume, com-
pleted each time with a 2-3-second breath-hold, and ex-
hales into the ERV. Peak expiratory tlow (PEF) should be
high, but without generating wheeze, bronchospasm. or
compression of collapsible airway segments. Flow-volume
loops (Fig. 5) show substantial overlap at or above the
effort-independent portion of a maximum expiratory flow-
volume maneuver. After several repeated breaths in this
manner, to mobilize peripheral secretions, the patient grad-
ually inhales a tidal volume from ERV. to functional re-
sidual capacity and then into the inspiratory reserve vol-
ume (IRV). Breaths in the range of functional residual
capacity begin Phase 2 (collection of peripheral and apical
secretions). Inspiration continues to be punctuated by the
breath-hold, and, again, compression of airways is mini-
mized during exhalation. Coughing or expectorating is
strongly discouraged. Finally. Phase 3 (evacuation) starts
from low-to-mid-IRV. with breath-holding inspirations fol-
lowed by a minimal forced expiratory maneuver or gentle
clearing of the throat. Unproductive ctiughing with forced
expiration is undesirable at any stage."''' Figure 6 dia-
grams the AD phases.

Respiratory Care • July 2002 Vol 47 No 7

781

Airway Physioi.ociy, Autogenic Drainagi;, and Activk Cycle of Breathing

5 -

2 3

Volume (L)

Peak flow

_—

_ Normal breathing

—

_ Autogenic drainage

'in

r
t

'-•f^

1 1

1 T

l^^J 1 .^

Volume (L)

— *^s

~ / V

' V

tf)

1 %

U-

'• ^

.'"^v

,-'^x ^

«^

i '^

1 .'I 1

! ,

^^.

, / . ^

■ A- .

1 2

Volume (L)

Fig. 5. Flow-volume curves showing overlap in the effort-independent regions of the maximum forced exhalation curve while performing
autogenic drainage in (A) bronchorrheic. (B) asthmatic, and (C) cystic fibrosis patients. (From Reference 19, with permission.)

Unfortunately there have been few studies published on
AD. In the CF literature. Ptleger et al-" compared AD to
high-pressure positive expiratory pressure and found both
significantly improved PFT values. Although AD caused
the most significant change, it produced the least amount
of sputum. A study by Davidson et al (never published in
a peer-reviewed journal)-' addressed patient preference for
AD (a complicated technique) to PD&P. In a planned
2-year crossover study there were no differences in clini-
cal status or PFT values, which improved in both groups.
Compliance was strictly monitored. At the end of the first
year, almost half the AD group refused to change over to

Phase 1

W\ V

M(\

ERV

Vfrc

invi

Fig. 6. Lung volumes dunng phases of autogenic drainage. Phase
1: Unsticking. Phase 2: Collection. Phase 3: Evacuation. ERV =
expiratory reserve volume. FRC = functional residual capacity.
RV -= residual volume.

PD&P because they thought AD was more effective. One
study comparing AD, ACBT, and PD&P found improved
ventilation (as measured via radiolabeled aerosol technique),
but AD caused a better improvement of airway clearance rale
centrally and for the v\hole lung than did ACBT. There was
no significant effect on PFT values or blood oxygen satura-
tion.-- A comparison of AD to PD&P showed a small but
statistically significant desaturalion with PD&P and a small
but statistically significant improved saturation with .AD.-'
Comparison of sputum rheology following flutter therapy
and AD showed no change with AD,-^ as might be expected.
Savci et al-^ compared AD and ACBT with COPD pa-
tients over a 20-day period. Both therapies statistically
improved forced vital capacity, PEF, P.,o,, blood satura-
tion oxygen, and exercise performance. For AD there was
also a statistical impio\ement in forced expiratory Nolume
in the first second, forced expirators flow during the mid-
dle half of the forced \ital capacity. P.,( ,),. and d_\spnea
score. The impro\ement in P,,, was clinically important
and statistically significant for both AD and .ACBT. but
forced vital capacity, forced expiratory volume in the first
.second, and PEF were clinicalls improved only by AD.
not by ACBT. Impixnement in PEF and P.,,,), were sta-
tistically better in the AD group than the ACBT group, and

782

Resi'IRMor^ Care • Ji'ly 2002 Voi 47 No 7

Airway Physiology, Autogenic Drainage, and Activh Cycli; oi BkI'Vuiing

FRC

BC FET

Fig. 7. Lung volumes during active cycle of breathing. IRV - in-
spiratory reserve volume. V^ = tidal volume. FRC = functional
residual capacity. ERV = expiratory reserve volume. RV residual
volume. BC = breathing control. TEE = thoracic expansion exer-
cises. FET - forced expiratory technique.

blood oxygen saturation increase was statistically higher
in the ACBT group than in the AD group.

Active Cycle of Breathing Teclinique

Like AD. ACBT (under the name forced cApiratory
technique [FET]) was developed (by Thompson and
Thompson, a physician and therapist working with pa-
tients in New Zealand) for secretion clearance in asthma.-"
ACBT is now the most common technique used in England.
From its earliest description as an airway clearance ad-
junct. ACBT included 1 or 2 huffs from mid-to-low lung
volumes, followed by a period of relaxed, controlled dia-
phragmatic breathing, with expansion breathing exercises.
Secretions mobilized to the upper airways would then be
expectorated and the process repeated.-'' Because of some
misinterpretation that the huffing was the major or only
part of the technique, its main proponents clarified and
emphasized the integral importance of relaxed breathing
control (BC) and thoracic expansion exercises (TEE). The
characteristics of effective and ineffective huffing were
also delineated.-* For further clarification, the name of the
technique was changed from FET to ACBT.

Figure 7 shows the respiratory volume movements of
ACBT. ACBT begins with BC, which is gentle, relaxed
breathing at the patient's own tidal volume and resting
respiratory rate. BC is also interspersed throughout the
cycle to allow recovery and prevent any increase in air
flow obstruction. The duration of BC is dependent on the
patient's signs of airtlow obstruction. BC may be fol-
lowed by TEE or several huffs (also termed FETs here-
after). TEE are deep. slow, relaxed inspirations to IRV.
with or without breath-holds, with quiet, unforced ex-
halations. These respirations help maximize ventilation
via collateral channels. This portion of the cycle aids
with problems of asynchronous ventilation and blocked
airways.

The FET is a series of huffs, usually starting from mid
lung volume, slightly above the tidal volume, with an easy.

Fig. 8. Three active-cycle-of-breathing routines. A. The simplest
routine, most applicable to mucus production without airway hy-
per-reactivity, atelectasis, or plugged airways. B. t^/lore periods of
or longer breathing control (BC) decreases potential for broncho-
spasm. C. Additional BC and thoracic expansion exercises (TEE)
for patients with airway plugging, atelectasis, or reactive airway
disease. FET = forced expiratory technique. (From Reference 30,
with permission.)

active exhalation into the ERV (but not to residual vol-
ume). The following huffs may start at higher lung vol-
umes (further into the IRV) and again move into the ERV
(but perhaps not as far as the first huffs).-' Physiologically,
this maneuver starts the EPP at a mid-lung, then this dy-
namic compression point moves peripherally with a con-
comitant migration in the jump point of air flow linear
velocity, promoting cephalad movement of secretions. The
next huff starts the EPP at a high lung volume, and it again
moves out peripherally. This combination can be visual-
ized as a "milking" action, as it forces the mucus toward
the central airways where it can be more easily expelled.

The fluidity of the ACBT allows easy adaptation to
patients with different disease states. The cycle is adjusted
for each individual patient. Figure 8 shows 3 examples of
the ACBT. The simplest is a repeating cycle of BC, TEE,
BC. FET. and would be most applicable for someone with
mucus hypersecretion but without much airway hyper-re-
activity, atelectasis, or airway plugging. The second ver-
sion, potentially for use with patients who tend to suffer
bronchospasm. intersperses more periods of. or longer du-
ration of BC. The third version involves additional BC and
TEE. which might be more helpful to someone with air-
way plugging, atelectasis, or reactive airway disease.

Much of the original research on ACBT is found under
the term FET. However, with an ACBT or FET article,
extremely careful reading of the methodology section is

Respiratory Care • Jul'i 2002 Vol 47 No 7

783

Airway Physiology, Au iogenic Drainage, and Active Cycle of Breathing

necessary id uiidcrsiaiiiJ vvhcilici' the nu)i.lalii> under in-
vestigation was the whole cycle or only the FET (hutT)
portion ofit." '- ACBT is an effective treatment in that it
improves pulmonary function ' ' '■* and airw a\ clearance. '^■"'
The addition of PD&P," positive expiratory pressure
techniques,"* and oscillating positive expiratory pressure
(Flutter)"'^" has been e\ aluated. and the majority of stud-
ies suggest that ACBT is equivalent or possibly more
effective. In the partial review of the literature above,
many of the articles were on CF patients.-''-'''''-'-"*''^
However. ACBT has also been evaluated in other dis-
eases and pathologies, such as asthma.-'' COPD.-^^'
chronic bronchitis. ■'"-•'- airway obstruction.'^ and mu-
cus hypersecretion. '-

(lie care pro\ider (therapist and physician) is seemingly in
a quandary as to whether airway clearance techniques are
appropriate. To answer that question, in the same breath as
1 express the need for larger randomized controlled stud-
ies. I also suggest the use of the H-of-1 study approach,''"
in v\ hich the patient is both the test subject and the control
subject. If an airway clearance technique seems appropri-
ate, obtain baseline values and observations of respiratory
health, initiate the airway clearance technique, and then
re-evaluate. The length of time before re-evaluation differs
based on the chronicity or acuteness of the process; if there
has been no clinical improvement, then discontinue the
intervention: however, if the patient has improved, then
continue with that clearance technique.

Evidence-Based Medicine

Summary

The physiologic rationales, theories, and studies upon
which AD and ACBT are based support their use in sev-
eral disease states. There are significant costs involved in
the performance of airway clearance techniques, both in
the therapist tinie needed to administer and teach the tech-
niques and in the time that patients or families expend.
Two excellent reviews recently questioned the evidence
supporting the use of any type of airway clearance.-" ■*-'
Many studies have shown no significant differences be-
tween the treated groups and the controls. In CF. most of
the studies compared one technique to another, because
use of airway clearance techniques has become the stan-
dard of care, so withholding treatment is considered un-
ethical, thus eliniinating true controls. The majority of
studies have been short or had small numbers of patients,
limiting the ability to determine a statistical difference. As
well, the difference between statistical significance and
clinical importance must be considered. For example, a
study showing p < 0.005 for a 3% change from baseline
in forced expiratory volume in the first second is statisti-
cally significant, but is it clinically important?

Nevertheless, chronic mucus hypersecretion is associ-
ated with higher mortality and faster decline in pulmonary
function .■*-''■■** It has been suggested that airway mucus sta-
sis may be important in certain lung pathologies (eg,
Pseudomoncis biofihn).^^ In asthma, secretions can worsen
ventilation-perfusion mismatch and may be associated with
more severe or life-threatening exacerbations. ■*'*-''^ The log-
ical assumption is that iniproved clearance will decrease
obstruction and work of breathing and thereby improve
oxygenation and potentially improve well-being and qual-
ity of life. It is not clear, however, whether airway clear-
ance techniques will affect those outcomes, even if they
improve pulmonary function or secretion production. Two
approaches are therefore necessary. First, better-designed
randomized controlled trials, of longer duration and larger
sample size, are essential. L'ntil such studies are perfornied

Airway clearance techniques are used to aid in nuicus
clearance in a \ariety of disease states. A clear understand-
ing of airway physiology elucidates the mechanisms
whereby AD and ACBT, "mere" breathing maneuvers, can
be successful in enhancing tnucociliarv clearance.

REFERENCES

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2. Mead J. Turner JM. Mackleni PT. Little JB. Significance of the
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3. Mead J. Expiratory flow limitation: a physiologist's point of view.
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4. Rossman CM. Waldes R. Sampson D, Newhouse MT. Effect of
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5. Rayl JE. Tracheobronchial collapse during cough. Radiology 1965:
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6. Clarke SW. Jones JG. 01i\ er DR. Resistance to two-phase gas-liquid
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12. Mackleni PT. Relationship between lung mechanics and ventilation
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21. Davidson AGF. Wong LTK. Pirie GE. Mcllwaine PM. Long-term
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22. Miller S. Hall DO. Clayton CB, Nelson R. Chest physiodieiapy m
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Giles DR. Wagener J. .Accurso FJ, Butler-Simon N. Shoit-term ef-
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App EM, Kieselmann R, Reinhardt D. Lindemann H. Dasgupia B.
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25. Savci S. Ince DI. Arikan H. A comparison of autogenic drainage and
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26. Thompson B. Thompson HT. Forced expiration exercises in asthma
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27. Pryor JA. Webber BA. Hodson ME. Batten JC. Evaluation of the
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28. Partridge C. Pryor J. Wbber B. Characteristics of the forced expira-
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29. Pryor J A. Active cycle of breathing technique. In: International Phys-
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30. Webber B A. Pryor J A. Physiotherapy techniques. In: Pryor J A. Web-
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31. Reisman JJ. Rivington-Law B. Corey M. Marcotte J. Wannamaker
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32. Middleton E. Clout C. Occleshaw C. Tindale WB. Parker BV, Bar-
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33. Webber BA, Hofmeyr JL. Morgan MDL. Hodson ME. Effects of
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34. Verhoon JM. li.ikker V\ . Sleik I'.l I lie v.ihie ol the forced expiration
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36. Hasani A. Pavia D. Agnew JE. Clarke SW Regional iiuiciis transport
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37. Sutton PP. Parker RA. Webber BA. Newman SP. Garland N. l.ope/.-
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38. Hofmeyr JL, Webber BA. Hodson ME. Evaluation of positive ex-
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39. Pryor JA. Webber BA. Hodson ME. Warner JO. The Flutter VRPl
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van Hengstum M, Festen J. Beurskens C. Hankel M. van den Brock
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42. van Hengstum M. Festen J. Beurskens C. Hankel M. Beekman F.
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48. Maxwell GM. The problem ot mucus plugging in children with
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49. Aikawa T. Shimura S. Sasaki H. Ebina M. Takishima T. Marked
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2(K)l;80(IO):786-796.

Rfspir.viorv Carf • }i\.\ 2002 Voi 47 No 7

785

Positive Pressure Techniques for Airway Clearance

James B Fink MSc RRT FA ARC

Introduction

Definitions of Positive Airway Pressure

Continuous Positive Airway Pressure

Expiratory Positive Airway Pressure

Positive Expiratory Pressure
Types of Resistors

Underwater Seal

Weighted Ball

Spring-Loaded Valve

Magnetic Valve

Fixed-Orifice Resister
Physiologic Rationale for Positive Airway Pressure
Administration Techniques
Administration Considerations
Aerosol Administration

Comparison of Flow, and Airway and Esophageal Pressures
Summary

Positive airway pressure (PAP) has been used since the 193()s to improve oxygenation, increase lung
volumes and reduce venous return. More recently, PAP has been identified as an effective method
of splinting airway during expiration, improving collateral ventilation, increasing response to in-
haled bronchodilators, and aiding secretion clearance in patients with cystic fibrosis and chronic
bronchitis. A range of devices, administration techniques, and evidence supporting their clinical use
is explored, suggesting that PAP is equivalent to postural drainage in the clearance of secretions.
PAP produced by threshold and fixed orifice resistors generate different characteristic flow, and
airway and esophageal pressure patterns that may contribute to different physiologic effects. Fur-
ther clinical studies are required to better understand the effects of these differences. Key words:
airway clearance, positive airway pressure, continuous positive airway pressure, expiratory positive
airway pressure, positive expiratory pressure, resistor. [Respir Care 2002;47(7):786-796]

Introduction

Positive airway pressure (PAP) is an effective tool in
promoting bronchial hygiene. Since the 1930s, positive
airway pressure has been used to improve oxygenation.

James B Fink MSc RRT f-AARC is l-cllow in Respiratory Science,
Aerogen Incorporated. Mountain View, Calit'ornia ■

Mr Fink presented a version of tiiis report at the 17ih Annual New
Horizons Symposium at the 47th International Respiratory Congress. San
Antonio. Texas. December 14. 2001.

Correspondence: James B Fink MSc RRT l-AARC, Aerogen Incorpo-
rated, 2071 Stierlin Court. Mountain View CA 94043. E-mail:
jtmk@aerogen.com.

increase lung volumes, and reduce venous return in pa-
tients with congestive heart failure. More recently, posi-
tive airway pressure for mobilization and clearance of se-
cretions has captured the attention of the cystic fibrosis
coniiiuinity, and a growing body of evidence has evolved
to support its use. This review explores how PAP is gen-
erated and the theoretical and empirical basis for its use as
a secretion clearance technique.

Definitions of Positive Airway Pressure

As defined in the American Association for Respiratory
Care's Clinical Practice Guideline.' PAP includes contin-
uous positive airway pressure (CPAP). positive expiratory

786

Rfspiratorv Care • Ji'i v 2002 Voi. 47 No 7

Posnivi; PrhssurI'. TixiiNiyuus ior Airway C'LhARANCB

Fig. 1 . A. During forced expiration and cough, external forces com-
press and close unstable airways, trapping gas and reducing the
ability to expel secretions. B. Positive airway pressure splints the
airway open during expiration, reducing air trapping and improving
expiratory flow. (From Reference 7)

pressure (PEP), and expiratory positive airway pressure
(EPAP). when used to mobilize secretions and treat atel-
ectasis. In the past 20 years PAP bronchial hygiene tech-
niques ha\ e emerged as effective ahernatives to chest phys-
ical therapy (CPT) for expanding the lungs and mobilizing
secretions. Evidence suggests that PAP therapy is more
effectise than incentive spirometry and intermittent posi-
tive-pressure breathing (IPPB) in the management of post-
operati\e atelectasis- ' and enhances the benefits of aero-
sol bronchodilalor delivery. ^^ Airway clearance techniques
such as forced expiratory technique, active cycle of breath-
ing, and huff are essential components of effective PAP
therapy.

Positi\e airway pressure should be differentiated from
IPPB and intermittent positive-pressure ventilation, which
are techniques of providing mechanical \cnlilation.''
Though PAP can occur during inspiration, the benefit is
derived from the pressure splinting open the airway
during expiration, increasing both lung xiilumes and
flows (Fii;. 1 ).

Continuous Positive Airway Pressure

CPAF' is (he ap|ilicalioM of posiiivc airway pressure dur-
ing both inspiration and expiration during spontaneous
breathing. A Ci^AP system consists of a pressurized circuit
with a threshold resistor on the expiratory limb. CPAP
maintains a consistent baseline airway pressure (5-20 cm
H^O) throughout the respiratory cycle. CPAP systems re-
quire a gas How greater than the patient inspiratory (low to
maintain the desired positi\e airway pressure.

Expiratory Positive Airway F'ressure

Expiratory positive airway pressure applies positive pres-
sure only during expiration. Subatmospheric pressures are
generated on inspiration, and positive pressure is gener-
ated during expiration. During EPAP therapy the patient
exhales against a threshold reslster. generating a preset
pressure of .'S-20cm H^O. Expiratory positive airway pres-
sure devices tend to be less complicated and less expen-
sive than CPAP systems, not requiring a high-flow gas
source.

Positive Expiratory Pressure

Positive expiratory pressure is generated as a patient
exhales through a fixed-orifice resistor, generating pres-
sure of 10-20 cm H,0 (although therapeutic use of pres-
sures up to 60 cm H,0 have been reported tt) be effective).
The fixed-orifice resister differentiates PEP from EPAP
and CPAP. The fixed-orifice resister only generates pres-
sure when expiratory flow is high enough to generate back
pressure from the orifice. In theory the threshold resister
does not produce the same mechanical or physiological
effects as a fixed-orifice resister. but further study is re-
quired to determine how those differences affect clinical
outcome.

Throughout expiration a threshold resistor exerts a pre-
dictable and relatively constant force on the expiratory
limb of the circuit. When the force is applied over a unit
area a constant threshold pressure is established. Pressure
exceeding the threshold opens the valve and allows expi-
ration, whereas pressure below the threshold will not open
the valve. Near the end of a breath, when the expiratory
pressure drops below the threshold, the valve closes, seal-
ing the circuit and stopping the How of gas. A true thresh-
old resister maintains constant pressure in the circuit, in-
dependent of changing flow rate.

Types of Resistors

Several type ot resistors are used to generate P.-XP dur-
ing expiration. They include:

Underwater Seal

With the untlcrwater seal system the expiratory limb of
the circuit is submerecd uniler water. The heiiihl ol the

Respiratory Care • J ley 2002 Voe 47 No 7

787

PosmvK Pressure Techniques for Airway Clearance

High
Expiratory Flow

Moderate

Expiratory Flow

No
Expiratory Flow

o=H

^>=\

'^ >

r ■

cinH20

o •

•V

■

.'-a

'ym

^j!l j^ Jl

Fig. 2. Resistors used to generate positive airway pressure, and
the impact of high, moderate, and no expiratory flow on airway
pressure. Water column (A), weighted ball (B), and spring-loaded

(C) are threshold resistors, which maintain the same airway pres-
sure independent of flow rate. In contrast, the fixed-orifice resistor

(D) generates pressure that correlates directly with flow rate. (From
Reference 8, with permission.)

water above the terminal end of the expiratory limb cor-
responds to the threshold pressure generated (Figure 2a).
A variant of the underwater seal is the water column de-
vice, in which the threshold pressure is generated from a
column of water above a diaphragm directly above the
expiratory limb of the circuit. Pressure in the circuit must
be greater than the pressure of the water to raise the dia-
phragm and allow gas to exit, so the threshold pressure is
a product of the water column height and the surface area
of the diaphragm.

Weighted Ball

With the weighted-ball system a precision-ground ball
of a specific weight sits above a calibrated orifice (imme-
diately above the expiratory limb of the circuit) in a hous-
ing with expiration ports. If the diameter of the orifice is
not the narrowe.st point in the expiratory limb of the cir-
cuit, the weight of the ball determines the threshold pres-

sure. Weighted ball systems require nielicuk)us attention
to vertical orientation to maintain consistent pressure, be-
cause if the system is tilted it can rattle or llutler during
expiration (see Fig. 2b).

Spring-Loaded Valve

With the spring-loaded \alve system a spring presses a
disc or diaphragm dt)v\n over the outlet of the expiratory
lintb of the circuit. The force of the spring must be over-
come for the disc or diaphragm to open and allow gas to
exit. The functioning of the spring-loaded valve is inde-
pendent of position or vertical orientation (see Fig. 2c).

Magnetic Valve

With the magnetic valve device a bar magnet attracts a
magnetic disc to seat on the outlet orifice. As the pressure
exceeds the attraction of the magnet the disc is displaced,
allowing gas to exit. The greater the distance between the
magnet and the disk, the lower the pressure required for
gas to leave the circuit.

Fixed-Orifice Resistor

A fixed-orifice resistor has a restricted opening of a
fixed size at the end of the expiratory limb. As gas reaches
the restricted orifice, higher fiow increases turbulence and
airway resistance, increasing pressure v\ithin the circuit.
For any given gas flow, the smaller the orifice the higher
the pressure generated. The expiratory pressure is flow-
dependent, so as flow decreases, pressure decreases. With
this device there is no threshold pressure to overcome
before gas can exit the system. In fact, there is no pressure
generated until expiratory flow is high enough to create
turbulence on exiting through the orifice (see Fig. 2d).

The fixed-orifice resistor was in large part abandoned
by the critical care community 20 years ago because of
concern that high pressure could be generated w ith chang-
ing flows (eg. coughing). However, the pressure generated
with a fixed-orifice resistor during a cough has not been
shown to be greater than that of a normal cough against
aclosed glottis, and no adverse effects have been associ-
ated with use of a fixed-orifice resistor.

Physiologic Rationale for Positi\e Airway Pressure

As an instinctive adaptation to disease, pursed-lips
breathing represents a functional predecessor to many of
our modern strategies of applying positive expiratory pres-
sure to the airway. Pursed-lips breathing is a simple pro-
cedure that many chronic obstructive lung disease patients
use to relieve air trapping caused by collapse of unstable
airways during expiration. It is believed that the resistance
at the mouth during a pursed-lips exhalation transmits back
pressure that splints the airways open, preventing com-

788

Respiratory Care • Julv 2002 Vol 47 No 7

PosiTivK Prhssure Techniquus for Airway Clearance

pressiiin and pivnuiliirc closiiiv. whkli is ihc same jirinci-
ple of operation as llic rixod-oriricc resistor."'"

As carlv as 1Q36 iho use of the posili\e pressure mask
for treatment ol' congestive heart faikue and earcUogeiiie
puhnonary edema was described." Barach et aP- reported
the use of "continuous positive pressure hreathing" via
mask with patients suffering from respiratory obstruction
and puhnonary edema. Imphcations for the treatment ot
atelectasis were not described until .^0 years later, when
Cheney et al" described P_,(,_ imprcnements after applica-
tion of expiratory resistance in anesthetized patients on
mechanical ventilation and speculated that this was caused
by reversing aKeolar collapse. In the 19(i()s Ashbaugh et
al'-* established the concept of positive end-expiratory pres-
sure (PEEP) as a technique to improve oxygenation in
acute respiratory failure and acute respiratory distress syn-
drome. In 1^71 Gregory et al'"^ found lower mortality from
respiratory distress among neonates who received CPAP.
PEEP and CPAP reduce the alveolar-arterial oxygen dif-
ference and right-to-left intrapulmonary shunt, increasing
functional residual capacity (FRC) in intubated patients
suffering acute respiratory failure.'""*

It was not until 1979 that PAP was suggested to have a
role in mobilization of secretions. Andersen et al''' dem-
onstrated reintlation of collapsed exci.sed human lungs with
CPAP via collateral \ entilation, suggesting that CPAP "has
a potential secretion clearing effect in that pressure is built
distal to an obstruction."

Andersen and Jespersen^" then made castings of human
lungs and identified communications between interseg-
mental respiratory bronchioles, concluding that collateral
ventilation might be important in normal lung function.

Interest in CPAP and PEEP for lung expansion and
mobilization of secretions began in the early 1980s.-' --
Andersen et al--* conducted a prospective, randomized, con-
trolled clinical trial, using a sequential analysis design, to
determine the effect of conventional therapy versus con-
ventional therapy plus periodic CPAP via mask, in the
treatment of 24 surgical patients with atelectasis. CPAP
was given each hour for 25-35 breaths, with an average
pressure of 15 cm H^O. At 12 hours, patients in the CPAP
group exhibited significantly greater improvement (P.,,,,
and radiographic findings) than the control group.

Soon thereafter, Pontoppidan advocated periodic CPAP
as a tool for treating postoperative pulmonary complica-
tions.-■* Several studies during the early 1980s explored the
application of various methods of PEEP and CPAP to
nonintubated patients, -'*^^" including comparisons of mask
CPAP to incentive spirometry, and of deep breathing and
coughing to IPPB, with various results. As more effective
strategies were developed. Stock et al-'*-'" concluded that
intermittent mask CPAP was as effective as incentive spi-
rometry or deep breathing and coughing in the return of
pulmonary function following thoracic or upper abdomi-

c
E

baseline during after during after
PEP5cmH,0 PEP15cmH,0

Fig. 3. Thoracic gas volume at functional residual capacity (solid
bars) and at total lung capacity (shaded bars) at baseline and
during and after 2 minutes of breathing with positive expiratory
pressure (PEP) (generated with a spring-loaded threshold resistor)
of 5 and 15 cm I-I2O. Functional residual capacity and total lung
capacity increase from baseline during therapy with both pres-
sures, returning to baseline after therapy. (From Reference 35,
with permission.)

nal surgery. Additionally, they suggested that mask CPAP
might be preferable, as it requires less effort and is pain-
less.

Ricksten et al' performed a randomized comparative
study of 43 upper-abdominal-surgery patients. They com-
pared postoperative complications, alveolar-arterial oxy-
gen difference, peak expiratory flow, and forced vital ca-
pacity (FVC) in a control group of patients using incentive
spirometry and a group using either CPAP or PEP. All 3
groups took 30 breaths each hour while awake, for 3 days
postoperatively. Although change in peak flow was not
different between the groups, FVC was greater in the CPAP
and PEP groups. The alveolar-arterial oxygen difference
increased uniformly for all groups for the first 24 hours,
but then decreased in the CPAP and PEP groups (being
insignificantly lower in the PEP group). Atelectasis was
observed in 6 of 15 patients in the control group. 1 of 13

Respirator"*' Care • July 2002 Vol 47 No 7

789

Positive Prhssure Techniques for Aikw a-i Clearance

P = 0.04

O 9S%

90%

75%

soy.

Mean

FEF 25-75

25%

10%
5%

Confidence
Intervals

Fig. 4. Change in percent of predicted for forced vital capacity (FVC). forced expiratory volume in the first second (FEV,). and forced
expiratory flow during the middle half of the forced vital capacity (FE\/25_75) over a 12-month period. Shaded bars represent a group of
patients who received postural drainage and percussion. Clear bars represent a group of patients who received positive expiratory pressure
physiotherapy. (From Reference 37, with permission.)

in the CPAP group, and 0 ot \f< in the PEP group. The
authors concluded that periodic PEP and CPAP are supe-
rior to deep breathing exercises with respect to impro\ing
gas exchange, preserving lung volumes, and pre\enting
postoperative atelectasis after upper abdominal surgery.
They also concluded that "the simple and commercially
available PEP mask is as effective as the more compli-
cated CPAP system." A simple PEP system certainly rep-
resents a cost savings o\er the use of a more complex
CPAP system, which requires a gas flow that will not
change the fraction of inspired oxygen (F|,) ) in response
to back pressure, pressure monitor, and oxygen analyzer.
Lindner et al." in a randomized study of 34 upper-
abdominal surgery patients, compared postoperative phys-
iotherapy and postoperative physiotherapy plus mask
CPAP. They found that the group treated u iih physiother-
apy plus CPAP had a more rapid recovery of vital capacity
and FRC, and fewer pulmonary complications. Campbell
et aP- randomized 71 abdominal surgcr\ patients into 2
groups. Group I did breathing exercises and huff cough-
ing. Group 2 did breathing exercises and huff coughing
plus PAP (w ith a water column ihreshold resistor adjusted
to produce pressures of .'i-l.'S cm Hi(). with the patient
exhaling through a mouihpicce). There were no differ-
ences in pulmonary function between the 2 groups, and the
incidence of respiratory complications was 31% in group
1 and 22'7f in group 2. which was not statistically signif-
icant. The authors concluded that PHP coukl serve as an
adjunct to routine CPT. particularly with postoperative
smokers, in that 43'f of the smokers in ilieir suuK devel-

oped respiratory complications, compared to none of the
nonsmokers (p < 0.01).

By preventing expiratory collapse. PEP is thought to
facilitate a more homogenous distribution of ventilation
throughout the lung, via the collateral interbronchiolar chan-
nels." Groth et al'^ measured lung function from the ex-
piratory port of the PEP mask with 12 CF patients and
found a significant change in FRC (p < 0.02), less trapped
gas (p < 0.05). and less washout volume (p < 0.05) than
pretreatment measurements. They concluded that the
changes were attributable to more even lung distribution
of ventilation and opening of airways that were otherwise
closed off during normal ventilation. In contrast, van der
Schans et a.\- reported that use of a 5 and 1 5 cm H^O thresh-
old resistor for 2 minutes increased FRC from 2.6 to 3.6 and
4.4 L. respectivelv. and an increase in total lung capacity
from .^.1 to >}) and 6.9 L (Fig. 3). These lung volumes
leturned to baseline immediaiely. They also found that use of
a threshold resistor did not intluence mucus clearance.

Because the patient must breathe down to subatmospheric
pressures on inspiration, both EPAP and PEP are believed
to impose a higher w i)rk of breathing than CPAP. Van der
.Schans et al "' examined the effect of EPAP w iih .^ cm H-,0
using a threshold resistor (Vital Signs. Towtowa. New
Jersev ) with S chronic obstructive pulmonary disease pa-
tients, measuring w ork of breathing and myoelectrical ac-
liviiv of the scalene, parasternal, and abdominal muscles.
During HP.'XP breathing at rest, mean specitic work of
breathing increased from 0.54 J/L to 1.08 J/L. expired
niiniite volume decreased from 12.4 L/min to 10.5 L/min.

790

Respirator'i Care • Jily 2002 Vol 47 No 7

Positive Pressure Techniques for Airway Clearance

Rotating Cap with 4 orifices

Orifice on cap aligns
with exit port on body

One-way valves

One-way vaJves

Fig. 5. Two commercially available positive expiratory pressure
devices. Above: Resistex, (Mercury Medical. Clearwater, Florida).
Below: TheraPEP (DHD Healthcare, Wampsville, New York). (From
Reference 8. with permission.)

and the ratio of dead-space volume to tidal volume de-
creased from 0.39 to 0.34. Phasic respiratory muscle ac-
tivity increased with EPAP. Dyspnea sensation during ex-
ercise test was hicher than durins: the test with undisturbed

hrcalhing. It is unclear sshclhcr the llxcel-orificc resistor.
more coninn)nly associated with PEP. would hn\ o the same
effect.

Mcllwainc ct aP' randomly assigned 40 patients, ages
6-17 years, to perform CPT or PEP therapy for a I -year
period. CPT consisted of 5-6 postural drainage positions,
with percussion for 3-5 min each, tollowcd hy deep breath-
ing exercises combined with vibration on expiration, forced
expirations, and vigorous coughing. These 30-min ses-
sions were done twice daily. PEP was performed with a
fixed-orifice resistor (Astra Meditec, Lund. Sweden). With
the patient in a sitting position, 1 5 tidal breaths with slightly
active expiration were taken through the device (approx-
imately every 2 min). The patient then performed 2-3
forced expiratory technique maneuvers, followed by cough,
and a 1-2 min period of relaxed, controlled breathing. This
sequence was repeated 6 times in a 2()-min session. In the
CPT group all the pulmonary function variables declined,
whereas the PEP group had positive changes in FEV, (p =
0.02) and FVC (p = 0.02) (Fig. 4). Reisman et al'» re-
ported a rate of decline similar to that experienced by the
CPT group (FEV, -1.9% of predicted per year). The PEP
group improved from baseline in FVC (+6.57%). FEV,
(-1-5.98%). and forced expiratory flow during the middle
half of the forced vital capacity ( + 3.3%). That was the
most convincing study to date that PEP may be superior to
standard CPT.

Administration Techniques

Equipment for PEP therapy consists of a soft, transpar-
ent, hand ventilation mask or mouthpiece. T as.sembly with
a one-way valve, a variety of fixed-orifice resistors (or
adjustable expiratory resistor), and a manometer (Figs. 5.
6. and 7). The mask is applied tightly but comfortably over
the mouth and nose. A mouthpiece can be used only if the
patient can maintain a reasonable seal and not release air
through the nose during the maneuvers. PEP therapy is
typically performed with the subject seated comfortably,
with elbows resting on a table. The subject is instructed to
relax while performing diaphragmatic breathing, inspiring
a volume of air larger than normal tidal volume but not
to total lung capacity, through ihc l-wa\ nuInc. Exha-
lation to FRC is active but not forced, through the re-
sistor chosen to achieve a PAP of 10-20 cm H^O during
exhalation (Table 1 ).

A series of 10-20 breaths are performed with the mask
or mouthpiece in place. The mask (or mouthpiece) is then
removed, and the individual performs several directed
coughs to raise secretions. This sequence of 10-20 PAP
breaths, followed by huff or forced expiratory technique is

Respiratory Care • }vl\ 2002 Vol 47 No 7

791

Posnivi: Prkssurr THcnNigui;s i-ok Aikvvav Clearance

EXPIRATORY RESISTOR
4 SETTINGS

MOUTHPIECE,

AEROSOL TUBING (oplional)

Fig. 6. Equipment tor positive expiratory pressure thierapy. (From Reference 7)

repeated 4-6 times per PEP therapy session. Each session
for bronchial hygiene takes 10-20 min and may be per-
formed 1 — \- times a day. as needed. For lung e.\pansion.
patients should be encouraged to take 10-20 breaths every
hour while awake.

Administration Considerations

Selecting an appropriate resistor with the right orifice
size is critical for effective therapy. The goal is to achieve
a positive expiratory pressure of 10-20 cm H-,0. with an
inspiration-expiration ratio of 1 :3 to 1 :4. Commonly, adults
achieve that pressure range with a tlow-restricting orifice
of 2.5 — 1.0 mm in diamclcr. The proper resistor helps pro-
duce the desired inspiration-expiration ratio of 1:3 to 1:4.
An in-line manometer can measure the expiratory pressure
to select the appropriate orillce si/e. Once the proper re-
sistor orifice (that generates peak pressures of 10-20 cm
H2O) has been determined, the manometer may be re-
moved from the system. A resistor with too large an orifice
produces a short exhalation and fails to achieve the proper
expiratory pressure. With too small an orifice the expira-
tory phase is longer, pressure can increase to above 20 cm
H,0. and the work of breathing may he increased. PEP

Fig. 7. AeroPEP Plus is a valved holding chamber designed to
combine aerosol therapy from a pressunzed metered-dose Inhaler
with a f Ixed-orif Ice resistor. (Courtesy of Monaghan Medical. Platts-
burgh. New York.)

sessions lasting more than 20 min ma\ cause fatigue. Dur-
ing exacerbations. indi\iduals are encouraged to increase
Ihe fh'cjiiency of PEP rather than extending the length of
individual sessions.

Aerosol Administration

Positive expiratory pressure and aerosol therapy done
simultaneously, either by hand-held nebuli/cr or metered-
dose inhaler (MDI). can improve the response to the bron-
chodilator. In a randomized crossover studs with S pa-

Tahle 1. Procedure for Administration of Positive Airway Pressure

1. Explain Ihat P.AP tfierapy is used to re-expand lung tis>ue and fielp
mohilize secretions.

Palienls should also he taught to pert'orni the huff.

2. Instruct the patient to:
(a) Sit comfortably.

lb) If using a mask, apply it tightly but comfortably over the nose
and mouth. If a mouthpiece is used, place lips Urmly around it
and breath through the mouth.

id) Exhale actively, but noi forcel'ull>. creating a PAP of 10-2(1 cm
H,0 during exhalation (determined with manometer during
initial Iherapy sessions). The inhalation should be approximately
1/.^ of the total breathing cycle (ie. inspiration-expiration ratio
\:M.

(e) Perform 1()-2U brealhs.

(f) Remove the mask or mouthpiece and perform 2-} hulls and
then rest as needed.

(g) Repeat above cycle 4-8 limes, not to exceed 20 minutes,
(h) When patients are also receiving bronchodilator aerosol,

administer in conjunction with PAP Iherapy by placing a
holding chamber/MDI or nebulizer at the inspiratory port of the
PAP device.

PAP - poMti\c airvsay pressure
MDI = mclcrcd-ilosc inhaler

792

Risi'iRATORV Care* JiLY 2002 Voi, 47 No 7

PosiiiM I'ki ssi'Ri- Ti:ctiNiyui;s ior AlK\vA^ Ci iaranci-:

Threshold Resistor

Flutter Valve

Fixed Orifice Resistor

High Flow

Gas Source

Oxygen or

Air

TUT

CPAP

EPAP

Flutter

PEP

Fig. 8. Comparison of airway pressure waveforms generated with continuous positive airway pressure (CPAP), expiratory positive airway
pressure (EPAP), weighted ball threshold resistor (Flutter), and fixed-orifice resistor positive expiratory pressure (PEP) devices. (From
Reference 8, with permission.)

Fig. 9. Flow (upper curve) and airway pressure and esophageal pressure (lower curve) during normal tidal breathing, measured with a
pneumotachometer placed at the airway and using a VenTrak monitor.

tients .sultering severe broncho.spasm, PEEP was applied
via face mask while administering nebulized bronchodila-
tors,-" Each patient had 2 PEEP treatments and 2 control
treatments (with zero end-expiratory pressure) at intervals
of 3 hours between each treatment. FEV,. FVC. and peak
flow improved significantly following PEEP treatments
(p < 0.03). PEEP improved the efficacy of bronchodilator
administration, possibly because of better distribution to
the peripheral airways.

Similar results were found when PEP was applicil in
conjunction with /B, agonists administered via MDl with

spacer. In a randomized crossover study. S patients alter-
nately received treatments of 2 puffs ot lerbutaline via
MDI without PEP. terhulaline via MDl with PEP. and
placebo via MDl w ith PEP.^ The results showed improve-
ment in peak expiratory How (p < ().()()() 1).

Conditions such as sinusitis, ear infection, epistaxis. or
recent facial, oral, or skull injury or surgery should be
carefully evaluated before a decision is made to iinliate
PEP mask therapy. Patients who arc e\|iericncing active
hemoptv sis or those with unrcsolvetl pncumolhoiax should
avoid PAP iherapv until those acule pulinonarv prohlems

Respiratory Care • Jut v 2002 Voi 47 No 7

793

Positive Pressure Techniques iok Aikwa'i' Clearance

80-r

-R4-

Fig. 10. Flow (upper curve) and airway pressure and esophageal pressure (lower curve) while breathing through a spring-loaded threshold
resistor (Vital Signs) with a 10 cm HjO valve.

Fig. 11. Flow (upper curve) and airway pressure and esophageal pressure (lower curve) while breathing through a fixed-orifice resistor
(TheraPEP).

have resolved. Though barotraunia and hemodynamic com- has been used for lung e.xpansion or secretion clearance, in

promise are possible with the use of positive pressure, no large part because of the techniques in\ dived in the ther-

complications have been reported when PEP mask therapy apy and the patient population.

794

Respiratory Care • July 2002 Vol 47 No 7

PosiriM Pri ssiiRi Ti ciiNiyn s ior Airway Ci.i;.\r.\nci-;

Comparison of Flow, and Airway and Esophageal
Pressures

To clarity terms to ttescribe PAP options, Pijzuie S shows
the difference in pressure patterns generated with CPAP. EPAP
(tiireshoid resistors), and PHP with a nxed-orifice resistor.

To better understand the relative effects of these devices, a
normal volunteer, with an esophageal balloon in place, was
asked to breathe (in accordance v\ith manufacturer instruc-
tions) through a variety of devices. Airway pressures and
flows were determined with a pneumotachometer placed at
the airway using a VenTrak monitor (No\ametri\. Connect-
icut). The upper panel represents flow ami the lower |ianel
shows airway anil esophageal pressure.

Normal tidal breathing (Fig. 9) shows a peak expiratory
flow of 35 L/min, with an inspiratory flow of 30 L/min.
Airway pressure fluctuates from atmospheric baseline by
< 1 cm H,0. Esophageal pressures are subatmospheric.
with tidal changes of -6 to -12 cm H^O; minor rhythmic
fluctuations of 0.5-2.0 cm H2O occur at a rate of 64/min
and correlate with the subject's heart rate.

The spring-loaded threshold resistor (recorded using a
Vital Signs 10 cm H-,0 valve) generates a distinct breath-
ing pattern. As expected with a threshold resistor, expira-
tory flow appears unrestricted at 40 L/min. with a square
wave pattern and prolonged expiration. Inspiration time is
similar but flows are higher. The airway pressure peaks
and maintains a plateau until exhalation begins (square
wave), and esophageal pressure equalizes with airway pres-
sure early in the expiratory phase. As active exhalation
continues past 1.5-2.0 s. esophageal pressure increases
above airway pressure by as much as 8-10 cm H^O (Fig. 10).

A fixed-oriflce resistor (TheraPEP. DHD Healthcare.
Wampsville, New York) (Fig. 1 1) restricts expiratory flow
to < 20 L/min, correlating to an airway pressure peak of
10 cm HiO. Airway pressure decreases with the expiratory
flow, with both returning to baseline prior to the next
breath. The esophageal pressure is nonnal on inspiration
but increases to positive during expiration, remaining con-
sistent to the last 0.5 s. reducing with reduced flow. During
a prolonged active expiration against a smaller orifice,
esophageal pressure steadily increa.ses with time and may
exceed airway pressure by the end of the breath.

It is clear from these waveforms that each method of
generating PAP generates a different correlation of flows
and airway and esophageal pressure patterns. Further stud-
ies are required to better understand the differences in
effect with these 3 modalities.

Summary

Positive airv\ay pressure, generated as CPAP. EPAP
and PEP has been shown to increase hnig volumes, im-
prove bronchodilator response, and im[iro\e secretion clear-

ance similar to postmal drainage, when combined with
PET or active cycle of breathing. l-!\|iiralory positive air-
way pressure and PEP devices lend to be inexpensive and
lequirc considerably less time anil physical acconnnoda-
tion lor |iroper use than postuial tirainage. and may be
more readily accessible lor ihe palicnl Ui iiilcgralc into his
or hei" dailv life.

RKKKRKNCKS

1 .American Association for Respiratory Care. AARC Clinical Prac-
iicc Guideline: Use of positive airway pressure adjuncts to bronchial
liyt^iene therapy. Respir Care I9y.^:.18(.'5):.'il6-52l.

2. Paul WL. Downs JB. Postoperative atelectasis: intermittent positive
pressure breathing, incentive spirometry, and lace-mask positive end-
expiratory pressure. Arch .Suri; l')Si;l lfi(7l:S61-S(i.^.

.V Ricksten SE. Benjilsson A. .Soderberg C. Thorden M. Kvisl H. Ef-
fects of periodic positive airway pressure by mask on postoperative
pulmonary function. Chest iy86;X9(6);774-781.

4. Andersen JB. Klausen NO. A new mode of administration of ncb-
uh/ed bronchodilator in severe hronchospasm, Eur J Respir D\s
.SuppI 1982:119:97-10(1.

5. Fri.schknecht-Christensen E. Norregaard O. Dahl R. Treatment of
bronchial asthma with terbutaline inhaled by conespacer com-
bined with positive expiratory pressure mask. Chest 1991:100(2):
} 1 7-.^2 I .

6. Kacinarek RM. Dimas S. Reynolds J. Shapiro BA. Technical aspects
of positive end expiratory pressure (PEEP). Part I. Physics of PEEP
devices. Respir Care I982:27( I2):I478-I489.

7. Mahlmeister MJ. Fink JB. Hoffman GL. Filer LF. Positive-expi-
ratory-pressure mask therapy: theoretical and practical consider-
ations and a review of the literature. Respir Care 1991 :.16( 1 1 1:
I2I8-I2.W.

8. Fink JB. Bronchial hygiene and lung expansion. In: Fink JB. Hunt
GE. editors. Clinical practice in respiratory care. Philadelphia: Lip-
pmcott Williams & Wilkms: 1999.

9. Thoman RL, Stoker GL. Ross JC. The efficacy of pursed-lips breath-
ing in patients with chronic obstructive pulmonary disease. Am Rev
Respir Dis I966:9.1( 1 ): 100-106.

10. Petty TL. Chronic obstructive pulmonary disease. New York: Marcel
Dekker: 1978.

1 1. Poulton HP. Odon DM. Leil-sided heart lailure wuh pulmonary oe-
dema: its treatment with the "pulmonary plus pressure machine."
Lancet 1936;231:981-983.

1 2. Barach AL, Martin J. Eckman L. Positive pressure respiratuni and its
application to the treatment of acute pulmonary edema and respira-
tory obstruction. Proc Am Soc Clin Invest l937:l(i:Wi4-(i80.

13. Cheney FW. Hornbein TF. Crawford EW. The effect of expiratory
resistance on the blood gas tensions of anesthetized patients. Anes-
thesiology l967:28(4):67()-f)76.

14. Ashbaugh DG. Petty TL. Bigelow DB. Harris IM. Continuous pos-
itive pressure breathing (CPPB) in adult respiratory distress syn-
drome. J Thorac Cardiovasc Surg I969;.'i7( l):3l-»l

l.'i. Gregory GA. Kilterman JA. Phibbs RH, Tooley WH. Hamilton WK.
Treatment of Ihe idiopathic respiratory distress syndrome with con-
tinuous positive airway pressure. N Eng J Med 1971 :2X4( 24): 1333-
1 340.

\(i. Pontoppidan H. Wilson RS. Rie MA. Schneider RC. Respiratory
intensive care. Anesthesiology I977:47(2):96-1 16.

17. Km/. J a. PEEP and CPAP in perioperative respiratory care. Respir
Care 1984:29(6):6l4-624; discussion 624-629.

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Positive Pressure Techniques for Airway Clearance

1 8. Garrard CS, Shah M. The effects of expiratory positive airway pres-
sure on function residual capacity in normal subjects. Grit Care Med
|y7S;6(5|:32()-33:.

I'). Andersen JB. Qvist H. Kann T. Recruilinj; collapsed lung through
collateral channels with positive end-expiratory pressure. Scan J Re-
spir Dis l979;6()(.'i):2W)-:66.

20. Andersen JB, Jespersen W. Demonstration of intersegmental respi-
ratory bronchioles in normal lungs. Eur J Respir Dis 1 980:61 (6):
337-341.

21. Branson RD. Hurst JM, DeHaven CB. Mask CPAP: stale of the art.
Respir Care I985;30( 10):846-857.

22. Branson RD. PEEP without endotracheal intubation. Respir Care
|y88;33(7):59S-610.

23. Andersen JB. Olesen KP. Eikard E. Jansen E. Qvist J. Periodic
continuous positive airway pressure. CPAP, by mask in the treatment
of atelectasis: a sequential analysis. Eur J Respir Dis 1 980:6 1 :20-25.

24. Pontoppidan H. Mechanical aids to lung expansion in nonintubated
surgical patients. Am Rev Respir Dis 1980:122(5 Pt 2):109-119.

25. Carlsson C, Sonden B, Thylen U. Can postoperative continuous
positive airway pressure (CPAP) prevent pulmonary complications
after abdominal surgery? Intensive Care Med 1981:7(5):225-229.

26. Martin JG. Shore S, Engel LA. Effect of continuous positive pressure
on respiratory mechanics and pattern of breathing in induced asthma.
Am Rev Respir Dis I982:126(5):8I2-817.

27. Stock MC. Downs JB. Administration of continuous positive airway
pressure by mask. Acute Care 1983/84:10(3-4):184-188,

28. Stock MC, Downs JB, Corkran ML, Pulmonary function before and
after prolonged continuous positive airway pressure by mask. Crit
Care Med 1984:12( 1 1 ):973-974.

29. Stock MC. Downs JB. Cooper RB, Lebenson IM, Cleveland J, Weaver
DE, et al. Comparison of continuous positive airway pressure, in-
centive spirometry, and conservative therapy after cardiac opera-
tions. Crit Care Med 1984:12(1 1):969-972.

30. Stock MC, Downs JB. Gauer PK. Alster JM, Imrey PB. Prevention
of postoperative pulmonary complication with CPAP, incentive spi-
rometry and conservative therapy. Chest 1985:87(2):I51-I57.

3 1 . Lindner KH, Lotz P, Ahneleld FW. Continuous positive airway pres-
sure effect on functional residual capacity, vital capacit> and its
subdivisions. Chest 1987:92( 1 166-7(),

32. Campbell T. Ferguson N. McKinlay RGC. The use of a simple
self-administered method of positive expiratory pressure (PEP) in
chest physiotherapy alter abdominal surger\. Physiotherapy 1986:
72:498-500.

33. Frolund L. Madsen F. Self-administered prophylactic postoperative
positive expiratory pressure in thoracic surgery. Acta Anaesthesiol
Scand 1986:30(5):38 1-385.

34. Groth S, Stafanger G. Dirksen H, Andersen JB. Falk M, Kelstrup M.
Positive expiratory pressure (PEP maski physiotherapy improves
ventilation and reduces volume of trapped gas in cystic fibrosis. Bull
Eur Physiopathol Respir l985:2l(4l:339-.343.

35. van der Schans CP. van der Mark TW. de Vries G, Piers DA, Beekhuis
H, Danken-Roelse JE. et al. Effect of positive expiratory pressure
breathing in patients with cystic fibrosis. Thorax 1991:46(4):252-
256.

36. van der Schans CP. de Jong W, de Vries G. Kaan WA. Postma DS,
Koeter GH, van der Mark TW. Effects of positive expiratory pres-
sure breathing during exercise in patients with COPD. Chest 1994:
105(3):782-789.

37. Mcllwaine PM. Wong LT. Peacock D, Davidson AG. Long-term
comparative trial of conventional postural drainage and percussion
versus positive expiratory pressure physiotherapv in the treatment of
cystic fibrosis. J. Pediatr 1997:131(41:570-574.

38. Reisman JJ, Rivington-Law B, Corey M, Marcotte J, Wannamaker
E, Harcourt D, Levison H. Role of conventional physiotherpay in
cystic fibrosis. J Pediatr 1988:1 13(4):632-636.

796

Respirators Care • }il\ 2002 Vol 47 No 7

High-Frequency Oscillation of the Airway and Chest Wall

James B Fink MSc RRT FAARC and Michael J Mahlmeister MSc RRT

Introduction

Deflnition

High Frequency Airway Oscillation Devices

Flutter Valve
Intermittent Percussive Ventilation (The Percussionator)
Hij;h-Frequency External Chest Wall Compression

The Vest

The Hayek Oscillator
Summarv

High-frequency oscillation (HFO), applied to either the airway or chest wall, has been associated
with changes in sputum attributes and clearance. The evolution of evidence, both in vitro and in
vivo, supporting the use of HFO is reviewed. Devices that apply HFO to the airway range from the
relatively simple mechanical Flutter and Acapella devices to the more complex Percussionaire
Intrapercussive Ventilators. The Vest and the Hayek Oscillator are designed to provide high-
frequency chest wall compression. Operation and use of these devices are described with examples
of differentiation of device types by characterization of flows, and airway and esophageal pressures.
Although HFO devices span a broad range of costs, they provide a reasonable therapeutic option
to support secretion clearance for patients with cystic fibrosis. Key words: high-frequency oscilhitiou,
mucus clearance, cystic fibrosis. [Respir Care 2002:47(7):797-807]

Introduction

High-frequency oscillation (HFO) of the air column in
the conducting airways represents one of several tech-
niques a\ailable to facilitate secretion removal in vulner-
able patients. A variety of devices are available that gen-
erate HFO by applying forces either at the airway opening
or across the chest wall. These devices range from plastic
hand-held products to table and floor models.

High-frequency oscillation was initially administered
only to the cystic fibrosis (CF) population, but a growing
body of peer-reviewed scientific literature and anecdotal
case studies suggests the value of HFO for a wide range of
pulmonary, neurologic, and neuromuscular disorders. This
review explores the range of devices, their principles of
operation, and the evidence supporting their use.

Definition

James B Fink MSc RRT FAARC is Fellow in Respiratory Science,
Aerogen Incorporated. Mountain View. California. Michael J Mahlmeis-
ter MSc RRT IS attiliated with the Respirator) Care Department, San
Mateo Communitv Hospital. San Mateo. California.

Mr Fink presented a version of this repon at the 17th Annual New
Horizons Symposium at the 47th International Respiratory Congress, San
Antonio. Texas. December 14. 2001.

Correspondence: James B Fink MSc RRT FAARC. Aerogen Incorpo-
rated, 2071 Stierlin Court. Mountain View CA 94043. E-mail:
jfink@aerogen.com.

The history of HFO started with its "anecdotal discov-
ery" 20 years ago, during research on high-frequency ven-
tilation. High-frequency pulsatile gas flow to the airway or
across the chest wall, at 3-30 Hz, was observed to increase
the volume of secretions at the upper airway. .Subsequent
studies with radiotagged aerosols confirmed the finding
that the cephalad flow of pulmonary secretions was accel-
erated during exposure to HFO.

High-frequency oscillation is thought to facilitate mu-
cus clearance through a variety of mechanisms. HFO re-
duces the viscosity of sputum in vitro.' A decrease in

Respiratory Care • Jul^ 2002 Vol 47 No 7

797

Hk;ii-Frkqi'f.ncy Oscillation of the Airway and Chest Wall

mechanical impedance of mucus appears to iiave a posi-
ti\e ettect on clearance imiuceci hy an in vitro simulated
cough. Dasgupta and colleagues demonstrated in an in
\ iiro model that similar frequencies applied to CF sputum
leduced \isct)eiaslicily with increasing oscillation lime.'
This was also true tor mucus gel stimulants: the higher the
applied frequency, from 0 to 12 and 22 H/. the greater the
reduction in \iscoelasticity.'

While the mechanism for the reduction in viscoelastic-
ily is unknown, likely possibilities involve the cooperative
LMitolding of the physical entanglements between the pri-
mary netw ork of mucus glycoproteins and other structural
macronu>lecules. the rupture of cross-linking bonds such
as disulfide bridges, or the fragmentation of larger mole-
cules such as DNA of F-actin, which are present as a
byproduct of infection and can increase mucus viscoelas-
ticity due to their interactions with glycoproteins.

Shearing at the air-mucus interface also appears to he a
significant factor in the enhanced tracheal mucus clear-
ance seen during HFO.^ The transient changes in airflow
with the inspiratory /expiratory phase of each high frequency
cycle, coupled with the augmented driving pressures, can
produce a cough-like force to the mucus layer. This shear
force is repeatedly applied at oscillatory frequencies that
approximate cilia beat frequency. It suggests that HFO
"resonates" with the lung's own cilia motions, nudging the
mucus layer upwards towards the larger airways and tra-
chea.

A third mechanism involves the redistribution of lung
volume. The capacity of HFO to increase the volume of air
distal to airways partially obstructed with mucus, coupled
w ith the exposure of those airw ays to enhanced expiratory
airflow and shear forces, seems a logical valuable mech-
anism of action of HFO.

It is likely that some combination iif change in mucus
rheology, airflow, shear forces, and voIlhuc redistribution
contributes to enhanced mucus clearance in patients who
respond to HFO. At present, there are 2 fundamental cat-
egories of HFO devices. One type applies the forces across
the chest wall. ie. high-frequency chest compression; the
other applies forces at the open airway, ie. high-frequency
airway oscillation. This distinction is important, since in
the case of commercially available high frequency airway
oscillation devices, the added application of positive air-
way pressure (PAP) also occurs. It is therefore difficult to
isolate the clinical value of HFO versus PAP.

It is important to differentiate percussion therapy from
HFO. In patients vviili chronic bronchitis, an electricallv
driven pad vibrating al frequencies of 29-49 Hz. with the
patient in a reclining position, produced only a nonsignif-
icant trend toward greater clearance and sputum produc-
tion.^ King et al'^ applied high-frequency chest wall oscil-
lation to anesthetized dogs al .^17 H/ and found an
increasetl tiaclical mucus clearance rate; .^40'/ of control

at 1.^ H/. In 1984. King et aP reported on tracheal mucus
clearance in anestheti/cd dogs thai underwenl HFO v ia the
airway opening and via the chesi wall. The rate was 240%
of control with HFO via the chest wall, whereas HFO via
the airway opening was less than or equal to control. HFO
via the chest wall was later demonstrated to enhance both
peripheral and central mucus clearance in dogs and to be
safe when moderate pressures were applied.''

George et al'^ found that HFO increased mucociliary
clearance in normal humans, with 9()'/( clearance of a
radiolabeled aerosol within 22.^ min among those who
underwent HFO, compared to 290 min among controls
(p < 0.05). In contrast, van Hengstum et al'" reported no
effect on tracheobronchial clearance from oral HFO com-
bined with forced expiration maneuvers in 8 patients w ith
chronic bronchitis. Comparing radiolabeled aerosol clear-
ance with ( I ) .^0-min sessions of forced expiratory tech-
nique w Ith huff, chest physical therapy (CPT) in 6 posi-
tions, and breathing exercises. (2) oral HFO at 9.2.'^-2.5
Hz. and (?<) control with huff only, they found that forced
expiratory technique was more effective than oral HFO or
control.

The role of airway oscillatiim in secretion clearance
remains unclear. Van Hengstum et al'" reported no effect
from oral HFO combined with forced expiration maneu-
vers on tracheobronchial clearance in chronic bronchitis.
Further studies are warranted.

Freitag et al" applied HFO at 14 Hz with asymmetrical
waveforms with expiratory bias (peak expiratory flow 3.8
L/s, peak inspiratory flow 1.3 L/s), inspiratory bias, and
posture to determine the effect of mucus clearance on
anesthetized sheep. Mucus clearance in the horizontal po-
sition with expiratory-biased HFO was 3.5 niL/IO min: in
the head-down tilt position without HFO it was 3.1 mL/10
min; and in combination it was I 1.0 mL/lO min. No clear-
ance occurred v\ ith inspiratory bias, even in the head-dovv n
position.

High Frequency Airway Oscillation Devices

Flutter Valve

The Flutter mucus clearance device (VarioRavv .SA. dis-
tributed by Scandipharm. Birmingham. Alabama) com-
bines the techniques of P.AP with HFO at the airway open-
ing. The device is pipe-shaped, with a steel ball in the
■"bowl" that is loosely covered by a perforated cap. The
weight of the ball serves as an expiratory positive airway
pressure (FPAP) device (which creates a pressure of ap-
proximately 10 cm HiO). while the shape of the bowl
allows the ball repeatedly to move on/off the bowl opening
("flutter"), which generates oscillations at about 15 Hz
(range 2-32 H/). with frequencv varying with device po-
sition. The proposed mechanism of actions include shear-

798

Re.spiraioky Carl • July 2002 Vol 47 No 7

High-Frequenci Oscii i.ation oi tiii- Aikwa'i" anii Ciii:st Wall

ing of" mucus from the airway wall by oscillatory forces,
prevention of early airway closure by stabilization of the
airways with EPAP, facilitation of cephalaii How ol mu-
cus, and changes in mucus rheology."

Although the Flutter device has been available m the
United States for almost 10 years, published data on its
efficacy are limited and equivocal.'- " In 1994. Konstan et
al" reported that the amount of sputum expectorated by 18
CF patients was more than 3 times the amount expecto-
rated with either voluntary cough (described as \igorous
cough every 2 min for 15 min) or postural drainage (up to
10 positions in 15 min). These findings merit close scru-
tiny because of the study design. Studied patients contin-
ued to receive their regular CPT throughout the 2-week
study period, so the study looked only at measured sputum
from an extra therapy session each day.'-* Patients with CF
or other chronic obstructive pulmonary diseases (COPD)
tend to suffer premature airway closure during vigorous
cough (as opposed to forced expiratory technique, huff, or
active cycle of breathing cough maneuvers), resulting in
trapped gas and retained secretions. Furthermore, national
guidelines suggest that effective postural drainage requires
3-15 min per position, so 10 drainage positions requnes
30-150 min to provide effective results.'^ It appears that
neither the cough nor the postural drainage parts of the
protocol were designed in light of available research to
provide optimal results (Table 1 ).

In 1994. Pryor et al"' studied 24 CF patients who aver-
aged > 1 1 .9 g of sputum per day using active cycle of
breathing technique as their standard bronchial hygiene.
Active cycle of breathing alone resulted in significantly
more sputum production than 10 min of Flutter therapy
followed by active cycle of breathing technique. The au-
thors expressed concern about the possibility of increased
sputum retention when the Flutter was used.

Homnick et al' ' studied 24 CF patients (age 8-44) dur-
ing hospitalization for acute exacerbation, and assigned
them to receive either standard CPT or supervised Flutter
therapy 4 times a day. Significant improvements were ob-
served between admission and discharge within each group.
but no significant differences were found in clinical score
or pulmonary function test results between the groups from
admission to discharge. Similarly. Padman et al'** reported
a comparison of Flutter. EPAP, and CPT in 6 of 15 CF
patients who completed the study, and found no signif-
icant differences in pulmonary function test results or
assessment variables, but reported a patient preference
for Flutter.

Oscillations are capable of decreasing mucus viscoelas-
ticity at frequencies and amplitudes achievable with the
Flutter device. App et al''' evaluated autogenic drainage
and Flutter in 14 CF patients, using a crossover design
with separate 4-week courses of autogenic drainage and
Flutter. There were no significant changes in forced vital

Table 1 . PrcKediire for Administration of Flutter Therapy

L Assess whether Fliuier lhcr;ip\ is imlicileil ^iiid desij;n a IrealmciU
program.

a. Bring equipmenl Ui ihe hedside and provide iniual therapy,
adjusting pressure settings to meet patient need.

b. After initial treatment or patient training, eommunieale Ihe
treatment plan lo the physieian(s) and nurse(s) and provide
instruction to the nursing stafL if required.

2. Explain that Flutter therapy is used to re-cxpaiid lung tissue and

help mobilize secretions. Patients should be taught to huff.
,^. Instruct the patient to:

a. .Sit comfortably

b. Take in a breath thai is larger than normal, but don't till the
lungs completely.

c. .Seal the lips firmly around the Flutter device mouthpiece and
evhale actively, but not forcefully, holding the Flutter valve at an
angle that produces maximum oscillation.

d. Perform 10-20 breaths.

e. Remove the Flutter mouthpiece and perform 2-3 huffs and then
rest as needed.

t Repeat above cycle 4-8 times, not lo exceed 20 minutes.

4. Evaluate the patient for ability to self-administer.

5. When appropriate, teach the patient to self-administer Flutter
therapy. Observe the patient conduct the self-administration on
several occasions to ensure proper uncoached Flutter technique
before allowing the patient to self-administer without supervision.

6. When patients are also receiving bronchodilator aerosol, administer
in conjunction with Flutter by administering bronchodilator
immediately preceding the Flutter breaths.

7. When visibly soiled, rinse Flutter device with sterile water and
shake/air dry. Leave the device within reach at patient hedside.

X. Send the Flutter device home with the patient.

9. Document, in the patient's medical record, procedures performed

(including device, number of breaths per treatment, and frequency).

paiient response to therapy, patient teaching provided, and patient

abililv to self-administer.

capacity, forced expiratory volume in the first second, or
sputum volume. At the end of the study both groups showed
a 67r (nonsignificant) improvement in forced vital capac-
ity. Sputum viscoelasticity was lower (p < 0.01) with
Flutter than with autogenic drainage. There was a nonsig-
nificant increase in sputum production during Flutter ther-
apy— more than during autogenic drainage. They also re-
ported that in vitro elastic properties of CF sputum samples
were affected by 19 Hz oscillations generated by a Flutter
device (for 15 and 30 min. with mean air flow velocity of
1.5 Us).

Weiner et al-" compared Flutter with sham treatment
with 20 COPD patients and reported improved COPD symp-
toms in the Flutter group, compared to baseline (p < 0.05).
After 3 months, forced vital capacity, forced expiratory
volume in the first second, and 12-min walk lest improved
in the treatment group, whereas the sham therapy group
was unchanged. Similarly. Girard and Terki-' studied 20
patients suffering from hyperproductive asthma and hy-
persensitivity to acarids as a major allergen. The subjects

Respiratory Care • Ji;l'>- 2002 Vol 47 No 7

799

HkiIi-Frequency Oscii.i ation of thr Airway and Chf.st Wail

Table 2. Test l.uns; Me;isurenienls

PEF

(L/min)

"peak

(cm H,0)

FPAP
(cm H,0)

WOB

(J/Li

P,nca„

(cm HP)

(mL)

Flutter

27.1

18.8

8.4

1 .406

7.5

450

TR(IOcmH.O)

39.0

I.";.?

7.5

1.2?l.'i

6.6

450

TR(l5cni H,0)

40.0

20.6

12.5

1 .6^4

9.9

700

FO (4.0 mm)

23.7

^.5

00.3

().73X

0.8

FO (3.0 mm)

13.4

10.2

0.3

0.714

1.6

PEF = peak expiratory flow

Pjvak ~ P^"^ airway pnssure

EPAP = expiralor) p^isilivc airway pressure

WOB = work of hrcalhini:

Pmiaii ~ mean airrtay pressure

ARV = change in residual volume

TR = threshold resistor

FO - fixed orifice resistor

used Fkitler tor .'^-iiiin sessions 5 times/d for 30-45 days.
There was objecti\e and suhjeclive inipro\eiiient in 18 of
tiie 20 patients.

To better understand how the Fkitter device compares to
other PAP devices, we-- compared Flutter with both tiircsh-
old resistors and fi.xed-orifice resistors to determine eftects
on the airway in vitro. Using a test lung (with a compli-
ance of 0.02 cm H^O/L). during passi\e exhalation (tidal
volume 500 niL. peak inspiratory tlow 40 L/min). we mea-
sured pressure patterns, peak expiratory flow, peak expi-
ratory pressure, mean airway pressure, work of breathing
(WOB). and changes in residual volume (Table 2).

The Flutter device had lower peak expirators tlow than
the threshold resistors but higher tlow than the fixed-ori-
fice resistors, hi all other respects the Flutter resembled the
threshold resistors. The fixed-orifice resistors had lower
peak tlow. peak and mean airway pressures. WOB. and
residual volume than either of the threshold resistors or the
Flutter (p < 0.001).

EPAP causes greater WOB than continuous positive
airway pressui'e (CPAP).- ' In the bench study by Schlobohm
et al-' both the Flutter and threshold resistors produced
a greater WOB than the fixed-orifice resistor. It is un-
clear what the effects of that higher WOB may be in the
severely obstructed COPD patient. Clearly, CPAP has a
role in reducing dyspnea,-^ -"^ whereas EPAP may not
(at least during exercise). Large-scale studies are re-
quired lo determine the relative benetits of Flutter ther-
apy to the less expensive PAP and breathing maneu\er
therapies.

Flow, and ,\irway and Esophageal Pressures. A nor-
mal \ohmtccr wiih an esophageal balloon in place was
askeil lo breathe while using a high-frequency oscillator in
accordance v^ith niaiuifacturer instructions. Airv\ay pres-
sures and tlows were measured v\ith a pneuniotachometer
placed al ihc airwas and recorded using a VciiTrak mon-

itt)r (No\ametrix, Medical Systems, Wallingford, Connect-
icut). Figure 1 shows the flow and the airway and esoph-
ageal pressures for normal tidal breathing. The
inspiratory-expirator) ratio was 1:2 and inspiratory and
expiratory flow were 30 L/min. Airway pressure fluc-
tuation was less than 1 cm H2O at atmospheric baseline.
Esophageal pressures were subatmospheric. with tidal
changes between -6 and -12 cm H2O. and minor rhyth-
mic fluctuations of 0.5-2.0 cm H^O correlate with heart
rate.

Figure 2 shows the results for the weighted ball thresh-
old resister (Flutter). The tluctuations of tlow and airway
pressure were similar during expiration, with < 0.5 cm
HiO fluctuation in esophageal pressure. Expiratory tlow >
40 L/min appears to be unrestricted: it decreases gradually
toward the end of expiration and generates a relatively flat
mean airway pressure. Esophageal pressure equalizes w ith
airway pressure early in the expiratory phase and exceeds
airway pressure by as much as 10 cm H^O as exhalation
continues past midpoint.

Intermittent Percussive Ventilation

Intermittent percussi\e \entilation (IPV) of the lungs as
a therapeutic form of CPT was advanced by Dr Forrest
Bird as a treatment for COPD patients. IPV involves a
pneumatic de\ice called a Percussionator (Fig. 3). IPV
was designed to treat diffuse, patch\ atelectasis, enhance
secretion mobilization and clearance, and deli\er nebu-
lized medications and wetting agents to the distal airways.-''

With IPV the patient breathes through a mouthpiece that
delivers high-tlow "mini-bursts" at rates of > 200 Hz (Fig.
4). During these percussive bursts of gas a continuous
airwav pressure is maintained while the pulsatile percus-
sive airwas pressure increases. Each percussive cvcle is
programmed bv the patient ttr clinician, bv holding down
a thumb bullon lor 5-10 seconds loi" the pciciissive in-

8UU

Rfspirator'i Care • Ji L^t 2002 Vol 47 No 7

Hir,H-FRi:oL'i;Nc^ Oscii.i aiion oi iiii Airway and Ciii:sr Wall

Fig. 1 . Flow (upper curve) and airway pressure and esophageal pressure (lower curve) during normal tidal breathing, as measured with a
pneumotachometer placed at the airway.

Fig. 2. Flow (upper panel) and airway pressure and esophageal pressure (lower panel) generated by a normal subject while breathing
through a Flutter valve.

spiratory cycle and releasing the button for exhalation. The
manufacturer recommends treatments of approximately 20
min. Impaction pressures of 25-40 psig are delivered with
a frequency from < 100 to 225 percussive cycles/min at
40 psig. The lPV-2 includes nonoscillatory demand CPAP
and/or oscillatory demand CPAP with intermittent man-
datory \entilation. C'jimcians have described use of IPV
through both inspiratory and expiratory cycles.

Natale et al-'' reported that a single IPV treatment was as
effective as standard CPT in improving acute pulmonary
function and enhancing sputum expectoration in 9 CF pa-
tients. Honinick et aP" later undertook a 6-month parallel,
comparative trial comparing IPV to standard manual CPT
in accordance w ith the Cystic Fibrosis Foundation's guide-
lines, in 16 CF patients (children and adults). They found
no significant tlifferenccs between the Ireatment groups

Respiratory Care • Jul^ 2002 Vol 47 No 7

801

Hir,H-FRi:oui;NCY Osciii ation f)F thh Airway and Chest Wall

Fig. 3. Intrapulmonary percussive ventilator (IPV) device. (Courtesy
of Percusslonaire Corporation, Sandpoint, Idaho).

and concluded the treatments were comparable. One IPV
patient had hght hemoptysis during the study.

Newhouse et al-'* compared IPV and Flutter to standard
CPT in children and adults with CF. No difference in sputum
quantity was found, but transient lower oxygen saturation
was found with CPT. All 3 therapies showed trends towards
lower lung volumes at I and 4 hours after administration.

Further studies would be valuable in determining the merit
of IPV in comparison to other lung expansion/secretion clear-
ance techniques. With so little published on IPV,-'"-'- one
might assume that contraindications and hazards are similar

to those associated with other forms of mechanical ventila-
lion. The manufacturer lists potential adverse effects to in-
clude sore ribs, fatigue, stress, and initation.

Flow, and Airway and Esophageal Pressures. Oral
HFO with IPV generates large fluctuations in How. which
are greater on expiration than on inspiration. Airway pres-
sure Ouctuutions of 4-8 cm H^O correlate to esophageal
fluctuations of 1-2 cm H^O. Airway pressure on expira-
tion is square-wave (increases to peak and plateaus until
expiration!; esophageal pressure increases to match airway
pressure in approximately 2 seconds (see Fig. 4).

Several disposable hand-held devices have recently been
introduced to the market, purporting to enhance mucus clear-
ance. A pneumatic, single-patient, multiple-use. high-
frequency intrapulmon;vy percussion aerosol deliver*' system
that oscillates at 6-14 Hz (PercussiveTech HF, Vortran Med-
ical Technology, Sacramento, California) has been introduced
in the market (Fig. 5). The Acapella (DHD Healthcare,
Wanipsville. New York) combines the resistive features of
the positive expiratory pressure of a PEP valve and the vi-
bratory features of a flutter valve to mobilize secretions in the
airway. Determination of the efficacy of these devices awaits
proof from published scientific data.

High-Frequency External Chest Wall Compression

High-frequency chest wall compression (HFCWC) has
been shown to increase tracheal mucus clearance rates and
lo correlate with improved ventilation in both animal and

16-

12-

B-

(/)

Fig. 4. Flow (upper curve) and airway pressure and esophageal pressure (lower curve) while breathing on an intrapulmonary percussive
ventilator (IPV) device.

802

Respir.atorv Carl • }vl\ 2002 Vol 47 No 7

HlCH-FRHQUENrV OSCII 1 ATIDN DF TIIH AlRVVAV AND ClIl'ST WaI.I.

Fig. 5. PercussiveTech HF pneumatic, single-patient, high-
frequency intrapulmonary percussion aerosol delivery system.
(Courtesy of Vortran Medical Technology, Sacramento, California.)

clinical studies. "■'■• As mentioned earlier. HFCWC was
originally developed to provide ventilatory support for pa-
tients tor whom conventional mechanical ventilation was
inadequate. Because HFCWC apparently mobilized secre-
tions in anesthetized dogs, its effect on tracheal mucus
clearance was studied. King et al reported in 1983" that
HFCWC in healthy anesthetized dogs increased the clear-
ance rate of tracheal mucus marker particles by as much as
3-fold, compared w ith quiet breathing. Secretion clearance
was also enhanced in peripheral airways, as measured with
inhaled radioaerosols.** Orally applied high-frequency air-
flow oscillations had no significant effect on tracheal mu-
cus clearance in the canine model. ^

HFCWC is believed to act by a combination of 3 pos-
sible mechanisms. In in vitro experiments." '"^ high-fre-
quency airflow oscillations (of comparable amplitude to
those achieved in vivo) reduced the viscoelastic and co-
hesive properties of mucus, which would make mucus
more easily clearable by the air-liquid interactions associ-
ated with cephalad airflow velocity bias. Second, the HFOs
may reinforce the mucus interaction with the cilia or the
natural harmonics of the chest wall. Evidence for this the-
ory comes from the fact that optimal frequencies for clear-
ance by HFCWC are in the range of 13-15 Hz.« Third.
HFCWC may stimulate the release of fresh secretions by
a vagal reflex mechanism, the fresh secretions being more
easily mobilized by airflow interactions.

Fig. 6. The Vest. (Courtesy of Advanced Respiratory, St Paul, Min-
nesota.)

The Vest

The Vest (Advanced Respiratory, St Paul. Minnesota),
previously known as the ThAlRapy Vest, was developed
by Warwick et al at the University of Minnesota. In 1988
this device received FDA clearance to market for secretion
clearance. More recently, in 2000 the FDA approval was
expanded to include sputum induction. Of all the devices
commercially available for HFO, The Vest has by far the
largest body of literature.

The device, designed for self-administered therapy, con-
sists of a large-volume variable-frequency air-pulse deliv-
ery system attached to a nonstretchable, inflatable vest
worn by the patient, which extends over the entire torso,
down to the iliac crest (Fig. 6). Pressure pulses, which fill
the vest and vibrate the chest wall, are controlled by the
patient with a foot pedal and applied during expiration or
the entire respiratory cycle. Pulse frequency is adjustable
from 5 to 25 Hz, with pressure in the vest ranging from 28
mm Hg at 5 Hz to 39 mm Hg at 25 Hz.

In theory, these vibrations to the chest wall cause tran-
sient increases in air flow in the lungs, to improve gas-
liquid interactions and mucus movement. Animal and clin-
ical studies demonstrated that the frequency of oscillations
and flow bias (inspiratory vs expiratory) are important in
determining effectiveness. Flow bias determines whether
secretions move upstream or downstream."' Conjecture
that this device has a role in lung expansion for patients
other than those with CF in the acute care setting has not
been empirically established.

The Vest has been reported to be more effective than
postural drainage in secretion clearance, on the basis of
several studies specific to CF patients.'" Kluft et al" stud-
ied HFCWC versus CPT/postural drainage in a crossover
trial of 29 CF patients, randomly alternated on a daily
basis. Each day included three 30-min therapy sessions.

Respiratory C.-\re • Jll^- 2002 Vol 47 No 7

803

Hi(,ii-Fi<i;yuiiNCY Oscillation ol thl Airway and Chhst Wall

a;MiaIj^I'^-J'''U~'^.xJ.X4.<aw^^

W -6-
E -8-

wviM J. ^ a''

-10--

\^'

^-^

Vy^V*^

Fig. 7. Flow (upper curve) and airway pressure and esophageal pressure (lower curve) while using The Vest.

Sputum was collected during and 15 iiiin after each ses-
sion. For HFCWC. 6 trequencies (6. 8. 14. 15. 18. and 19
Hz) were applied tor 5 min each, in order of increasing
frequency. Each frequency application was followed by a
deep breath with huff, with the device turned off. and the
patient actively coughed. Patients received nebulized nor-
mal saline via small-volume nebulizer during treatment.
CFT/postural drainage included chest percussion with pos-
tural drainage of 5 sites for 2-3 min per position, followed
by vibration and forced cough. The 5 positions rotated
during each of 3 sessions to cover all lobes in 24 hours.
The CRT sessions did not include huff and there was no
mention of nebulization of saline. Sputum wet and dry
weights were determined for each type of therapy. There
was significantly more sputum production with HFCWC
than with CPT.

Arens et al"* studied 50 CF patients randomly assigned
to 3-times-a-day therapy during admission for acute exac-
erbation. CRT was performed with 6 positions over 30 min
(4 lying and 2 sitting with 4 min of percussion in each
position). HFCWC treatments consisted of 6 frequencies
for 4-5 min each. All patients received aerosol with al-
buterol prior to CPT or during therapy. The 1-hour wet
weight of sputum with HFCWC was greater than with
CPT ( 14.6 ± 2.9 g vs 6.0 ± 1 .8 g, p < 0.035). The authors
concluded that HFCWC and CPT were et|ually safe and
effective when used during acute exacerbation.

Flow, and Airway and I'.sopha^eal Pressures. HFCWC

with The Vc.\l results ni a relati\el) normal flow pattern,
which appears unrestricted. As flow decreases, the fluctu-
ations increase. Airway pressure remains at baseline, like

normal tidal breathing, with fluctuations of 0.5-0.75 cm
HiO. Unlike PAR and Flutter, esophageal pressure re-
mains subalmospheric. with fluctuations of 0.25- 1.0 cm
H,0 (Fig. 7).

The Hayek Oscillator

The Hayek Oscillator is an electrically powered, micro-
processor-controlled, noninvasive oscillator ventilator that
uses an external, flexible chest enclosure (cuirass) to apply
negative and positive pressure to the chest wall to deliver
noninvasive oscillation to the lungs (Fig. 8). The negative
pressure generated in the cuirass causes the chest wall to
expand for inspiration; positive pressure compresses the
chest to produce a forced expiration. Both inspiratory and
expiratory phases can be active and not reliant on passive
recoil of the chest. Expiratory pressure can be positive,
atmospheric, or negative, allowing ventilation to occur
above, at, or below the patient's normal functional residual
capacity. Several groups have reported success in using
this device as a method of ventilatory support.*' "•- Four
adjustable xariables w ilh the Hayek include frequency range
(8 to 999 oscillations/min), inspiration-expiration ratio (6: 1
to 1:6). and inspiratory pressure (-70 to 70 cm H,0).

Clinicians' anecdotal observations of "spontaneous ex-
pulsion of secretions"-" ■'-' during high-frequency ventila-
tion has led to development of several discrete secretion
management program recommendations, in which the chest
is oscillated through 2 sets of cycles: several minutes at a
high-frequency of up to 999 (usually 600/720) cycles/min
at an ins|iiralion-e\piration ratio of 1:1. followed b\ 60/90

804

Rl.si'ikaiok'i Care • Jul^ 2U02 Vol 47 No 7

Hic;ii-Fki oi'i:n(">' Oscii i mion oi iiii. Aikway and C'iiisi Wai.i.

Cuirass

Cuirass
short tubes

Pressure
sensor tubing

Keyboard/
control unit

Power unit

Cuirass
Y-connector

Wide bore tube

Fig. 8. The Hayek Oscillator (Breasy Medical Equipment Ltd. Lon-
don, United Kingdom). (From Reference 39, with permission.)

cycles/min at an inspiration-expiiation ratio of 5:\. The
settings can he clianged aecording lo llie patient's per-
cei\ed need. No ivjioris have been published on the elTi-
eaes of this or similar protocols lor secrelioii managenienl
with the Hayek.

HFO applied \ia the airway or via the chest wall and
CPT have coni|iarable aiiynienlini; elTecIs on expectorated
spulinn weight, vvilhoiil chansjinii pulmonary function test
results or oxygen saluiaiion.^^ According to earlier exper-
iments, prerequisiles ioi' optimal cephalad transport ot mu-
cus by air-li(.|uid interaction include air How with an ex-
piratory bias, which neeils to be in the range of 1-3 L/s.
and for airway oscillation at S-I.'i H/. This was confirmed
in an experiment, and high-frequency chest wall oscilla-
tion was found lo improve oxygenation and ventilation in
patients with normal linigs, in patients with respiratory
failure, and in patients with COPD.

Flow, and Airway and E.sophageal Pres.sures. With
the Hayek Oscillator, expiratory How appears unrestricted.
airway pressure fluctuations are greater (up to ± 1.3 cm
H^O) on expiration, with subatmospheric esophageal pres-
sure, and with tTuctualii)ns of 0.5-1.0 cm H2O (Fig. 9).

It appears that the HFCWC devices create similar air-
flow and pressure patterns, with differences in frequency.

Summary

These maneuvers and devices may have a place in pro-
moting bronchial hygiene in CF patients. It is intuitively
attractive to believe that maneuvers that reinforce or com-

■v4'JVt>'>/*1

'"^''^/WVWV^ •''^'''"^

'■jtfMlWPrM

tv^■^^./V.^<^«

r^vy-^-^v^-^v^y^^J

Fig. 9. Flow (upper curve) and airway pressure and esophageal pressure (lower curve) while using the Hayek Oscillator.

Respir.atory C.'\rk • JiT.'i 2002 Voi, 47 No 7

805

Hic;h-Frequency Oscillation of thf. Airway and Chest Wall

plenient normal mechanisms of mucociliary clearance pro-
vide improved secretion clearance with considerably less
effort and inconvenience than postural drainage. Though
the research has not identified one "superior" therapy, we
have identified a substantial niniiber of \ iable alternatives
that appear to be as good as or belter than postural drain-
age. In the next se\ eral decades CF patients may have the
need and opportunity to use these devices and techniques,
and the ultimate key to the success of any one of them may
be how comfortable and convenient it proves for the in-
dividual patient.

Utilizing the AARC Clinical Practice Guidelines as a
framework for developing protocols for use. and defining
desirable end points that include (but are not limited to)
sputum volume. HFO devices offer the clinician a valuable
tool in the management of patients who may need assis-
tance with secretion clearance and atelectasis.

REFERENCES

1. Chang HK. Weber ME, King M. Mucus transport by high-frequency
nonsymmetrical oscillatory airtlow. J Appl Physiol 1988:65(3): 1 203-
1209.

2. Dasgupta B. Tomkieuic/ RP. Boyd W'A. Brown NE. King M. Ef-
fects of combined treatment with rhDNase and airtlow oscillations
on spinnability of cystic fibrosis sputum in vitro. Pediatr Pulmonol
1995:20(2):78-82.

3. Lindemann H. [The value of physical therapy with VRP I - Desitin
(•■Flutter")] Pneumologie 1992:46(1 2 ):626-630. /trnV/f in German

4. King M. Zidulka A. Phillips DM. Wight D. Gross D. Chang HK.
Tracheal mucus clearance in high-frequency oscillation: effect of
peak flow rate bias. Eur Respir J 1990:3(1):6-13.

.5. Holody B. Goldberg HS. The effect of mechanical vibration phys-
iotherapy on arterial oxygenation in acutely ill patients with atelec-
tasis or pneumonia. Am Re\ Respir Dis l98l:l24(4):372-375.

6. King M. Phillips DM. Gross D. Vartian V. Chang HK. Zidulka A.
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7. King M. Phillips DM. Zidulka A. Chang HK. Tracheal mucus clear-
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8. Gross D. Zidulka A. O'Brien C. Wight D, Eraser R. Rosenthal L.
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9. George RJ. Johnson MA. Pavia D. Agnew JE. Clarke SE. Geddes
DM. Increase in mucocilliary clearance in normal man induced by
oral high frequency oscillation. Thorax l985:40(6):433-7.

10. van Hengstum M, Festen J. Beurskens C. Hankel M, van den Broek
W, Corstens F. No effect of oral high frequency oscillation combined
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chronic bronchitis. Eur Respir J I990:3( 1 ):14-IS.
Freitag L. Long WM. Kim CS. Wanner A. ftemoval of excessive
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12. Huls G. Boldl A. Kicselmann R. Lindemann H. Child physiotherapy
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2(K)4-20I1.

13. Konsian MW. Stern RC, Doershuk CF. Efficacy of the flutter device
for airway mucus clearance in patients with cystic fibrosis. J Pediatr
1994:124(5 Pt l):689-693.

14. Mahcsh VK. McDougal J A. Haluszka L. Efficacy of the Flutter

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Respiratory Care • July 2002 Vol 47 No 7

807

Airway Clearance Techniques for the Patient
with an Artificial Airway

Robert M Lewis ND RN RRT

Introduction

Kffects of Artificial Airways on Mucus Clearance

Impaired Mucus Transport

Increased Risk of Aspiration

Abnormal Bacterial Colonization
Goals of Airway Clearance Techniques with the Intubated Patient

Prevent Catastrophic Obstruction of the Endotracheal Tube

Prevent or Reduce Peripheral Airway Obstruction

Reduce Infectivity of Secretions
Components of Airway Clearance Strategies

Prevent Secretion Dehydration

Reduce Upper Airway and (Gastrointestinal Tract Bacterial Colonization

Prevent Secretion Accumulation abo\e the Kndotracheal Tube Cuff

Prevent Aspiration of Secretions from the Supra-Cuff Space

Prevent Development of Biofilm

Prevent Disruption and Aspiration of the Biofilm

Maintain Patency of the Central Airway

Compensate for Lack of Normal Cough

Compensate for Lack of Spontaneous Position Change
Summary

Artificial airways provide both opportunities and challenges to clinicians concerned with airway
clearance. For example, the artificial airway provides direct access to the lower airways for catheter
suctioning of secretions and a direct route for lung instillation of medications that promote secretion
mobilization. At the same time, the presence of an artificial airway impairs natural mechanisms of
airway clearance — coughing and mucociliary function. Artificial airwa>s are invariably coated
with an antibiotic-resistant bacterial biofilm that can be introduced into the lung by several com-
monly applied airway clearance techniques. This factor is rarely considered during research on
airway clearance techniques for patients with artificial airways. This review summarizes current
research on airway clearance techniques for patients with artificial airways, with special attention
to the implications of the bacterial biofilm. Directions for future research are also discussed. Key
words: ariificidi airnay. airnay clearance techniques, aspiration, biofilm. saline instillation, secretions,
siictioiuufi, ventilator-associated pi^ewnoitia, VAP. [Respir Care 2002;47(7):808-817]

Introduction lion, phiceincnl o{ m\ ETT increases the lisiv ol pulmonary

inl'eetioii. in part because of the development of a haeteria-
The presence of an endotracheal tube (ETT) impairs the rich biotiim on the interior and exterior surlaces of the
body's normal mechanisms of airway clearance.' In addi- tube.-' Some generally accepted methods of secretion re-
moval in the intubated patient, such as endotracheal suc-
tion. can disrupt the biofilm and introduce bacteria into the

Robert M Lewis ND RN RRT is at'l'ilialecl willi the Department ot Emer-
gency Medicine. Emory University. Atlanta. Georgia.

Dr Lewis presented a version of ihis ropun ai ihc 17ih .Xnnual New Correspondence: Rohorl M Lewis ND RN RRT, Department of Emer-

Horizons Symposium at the 47th Inlernatiiina! Rcspnatiiry Congress. San gency Medicine. Emory University, .Atlanta GA .■*()-^22. E-mail:

Antonio, Texas, December 14,2001. rnilewis2(Xi(?'vahoo.com.

808 RESPlRATOR^■ Carh • July 2002 Voi 47 No 7

Aikw \^ Ci i;aranci: Ti (liNion s i ok mr Patii.nt wnii an Ariiiiciai Airway

lower airway."* Other airway clearance techniques, xiich as
chest wall percussion and \ibration. may have a similar
effect. Introduction of bacteria into the airway of a criti-
cally ill patient can result in a tissue-damat;ini; mnamma-
tory process, as well as life-lhreatenini; pneumonia.^ Stud-
ies of airway clearance techniques applied to the intubated
patient must therefore include nosocomial pneumonia as a
major outcome variable, as well as the more immediate
effects of airway clearance procedures on other variables,
such as sputum volume and lung mechanics.

Bacterial infection of the airway can also trigger a sys-
temic mllammalory response.'" which can result in addi-
tional morbidity and extra-pulmon;iry organ ilysfunclion.
These effects may be hard to anticipate and identify, but
their presence could be inferred from differences in overall
mortality, length of stay, and hospital expenditures. These
variables are rarely addressed in studies of airway clear-
ance techniques applied to the intubated patient. This re-
view therefore is written from the perspective that airway
clearance techniques must be evaluated not only by mea-
suring such factors as \olume of sputum produced and
changes in pulmonary function, but by broader measures.
such as total mortality and length of intensi\e care unit
(ICU) stay.

An evaluation of airway clearance techniques for the
intubated patient must also recognize the role of upper
airway bacterial colonization in the pathogenesis of ven-
tilator-associated pneumonia (VAP). Therefore, this re-
view is written from the perspective that minimizing bac-
terial colonization of all structures in the airway (including
the teeth and sinuses) must he addressed when evaluating
airway clearance techniques.

Effects of Artificial Airways on Mucus Clearance

Impaired Mucus Transport

The placement of an endotracheal or tracheostomy lube
presents both challenges and opportunities for those con-
cerned with application of airway clearance techniques.
The artificial airway, although allowing for direct access
to the lower airway and direct aspiration of secretions, also
interferes with the body's own mechanisms of secretion
clearance. In normal humans, removal of mucus from the
lung depends on the mucociliary escalator. When mucus
production is excessive, coughing is also necessary for
airway clearance. Endotracheal intubation interferes with
both of those processes.

The placement of an ETT results in substantial damage
to the airway. Since it is a foreign body, its presence in the
larynx and trachea stimulates an inflammatory response,
which both increases mucus production and impairs ciliary
action.' Electron microscopy evaluation of mucosa trom
both humans and animal models demonstrates substantial

r^hlc 1 t^lTccl'i ot Ariiiiciai Airways on Sccrelidn .'\cciiTiiul:ilion
anil Clearance

Muciiciliary transport mtpuircd

.Secretion imiiluclion nicreased

Hacteriology ol secretions altercil

.Swallowini! inipaireii

Functional separation ol ;jastrointestiiial tract and respiratory tract

\ iolaled
Aspiration ol oropharynjical secretions
Cough dynamics altered
Muscle strength decreased

deiuidaliiMi of cilia li'om the liachea.' '^ Changes are great-
est at the site of the ETT cuff. The ETT is also associated
with damage to the tracheal epithelium, exposing the base-
ment membrane. Injury to this layer promotes bacterial
adherence and colonization."

The increased secretion of mucus, coupled with ciliary
dysfunction and damage, results in accumulation of secre-
tions, which act as a reservoir for bacterial pathogens. The
presence of bacteria promotes a chronic inllammatory state
in the intubated patient, with proteolytic enzymes being
released by neutrophils. This further damages cilia and epi-
thelial cells, resulting in a cycle of further infection, in-
creased mucus productit)n. and continuing airway damage.'

Cough is substantially impaired when an ETT is in place.
Glottic closure is prevented, so the patient is unable to
generate the pressure required for the "explosive" phase of
the cough. In addition, because of the increased work of
breathing imposed by the tube, the patient may be unable
to inspire a sufficiently large tidal \i)lume to generate an
effective cough. The increased work of breathing may lead
to respiratory muscle fatigue, further limiting the effec-
tiveness of the cough. An ETT also bypasses the airway's
normal humidifying mechanisms, which increases secre-
tion viscosity, which further burdens the normal mucus
clearance processes.

Increased Risk of Aspiration

Another consequence of ETT placement is interference
with the nomial functional separation of the gastrointesti-
nal and respiratory tracts. Inability to close the glottis, as
well as the presence of the tube in the oropharynx, pre-
vents the patient from swallowing, so oropharyngeal con-
tents can more easily enter the lungs. If. because of vom-
iting or gastroesophageal lellux. acidic gastric contents
enter the oropharynx, aspiration into the lungs can result,
and acid injury to the airway mucosa can further perpet-
uate the inflammatory cycle. As well, acid-induced airway
injury increases the ability of bacteria to adhere to cells.'"
Table I summarizes the effects of artificial airways on
secretion clearance.

Respiratory Care • Juey 2002 Voi 47 No 7

809

AlRWA^' Cl.HARANCE TECHNIQUES FOR THE PaTIENT WITH AN ARTlFiriAL AlkWAY

Fig. 1. Scanning electron microscopic image of a Staphylococcal
biofilm from an endotracheal tube. (Courtesy Professor Sean P
Gorman, School of Pharmacy, Queen's University of Belfast, Bel-
fast. United Kingdom.)

Abnormal Bacterial Colonization

Another problem relutcd to the presence of an artificial
airway is the development of a bacteria-rich biofilm on the
interior and exterior surfaces of the tube. This biofilm.
composed of a dense matrix of polysaccharides, bacteria,
and white blood cells (Fig. 1), can be detected in ETTs
several hours after intubation.' Antibiotics and other host
immune factors cannot penetrate the ETT, so the bacterial
concentration can increase unchecked. The biofiltn thus
acts as a reservoir for iiifoction/rc-infection of the intu-
bated patient.

The bacteria colonizing the biolilm may come from the
gastrointestinal tract."'- Delayed gastric emptying, in-
creased gastric pH due to stress ulcer prophylaxis, and the
presence of gastric tubes all contribute to multiplication
and migration of these organisms into the oropharynx.''
Oropharyngeal secretions in turn migrate along the ETT,
pooling in the space above the inflated ETT cuff. Inter-
mittent aspiration of these secretions past the cuff results
in colonization of the lower airway, including the portion
of the airway immediately below the ETT opening. There-
after, the interior lumen of the ETT is colonized and the
biofilm forms and grows cephalad.'

Organisms commonly found in the ETT biofilm include
Pseiidomonas aeruginosa. Staphylococcus aureus. Enlero-
coccus faecalis, and Candida species.- The biofilm bacte-
ria transform into highly antibiotic-resistant forms, even
though the parent organisms in the lower airway may re-
main antibiotic-sensitive. This transfornwtion appears to
be mediated by quorum sensing and alterations of gene
expression and protein production." Table 2 summarizes
the clinically relevant features of ETT biofilms. Since pre-
vention of bacterial infection is an important goal of an\
airway clearance technique in the patient with an artificial
airway, the presence of the biofilm is obviously important
in planning and evaluating care (if the intubated patient.

Table 2. Bacterial Biofilms in Endotracheal Tubes

General Characlerislics

• BiotHni noted in endotracheal tube within hours of intubation

• Composed of white blood cells, bacteria, and polysaccharides

• Highly antibiotic-resistant
.Sequence of Development

1. Bacteria colonize stomach and oropharynx

2. Bacteria colonize trachea and exterior of endotracheal tube

3. Secretions aspirated around cuff -^ lower airway colonization

4. Retrograde colonization of interior of endotracheal lube

5. Rapid development of biotllm

6. Rapid development of antibiotic resistance

Hagler and Traver* demonstrated that generally accepted
suctioning practices can result in subslantial contamina-
tion of the lower airway. They showed that passing a
suction catheter through the ETT can disrupt the biofilm,
releasing up to 60, (MM) colonies of bacteria into the airway.
Instillation of a small amount of saline into the ETT in-
creased the number of colonies dislodged to 310.000.

Aspiration of those large numbers of antibiotic-resistant
organisms can result in pneumonia, or, at the very least,
exacerbation of the airway inflammation associated with
intubation. Focusing on short-term results of airway clear-
ance techniques, such as volume of secretions removed.
effects on lung mechanics, or effects on oxygenation, ig-
nores the impact of these techniques on the biofilm. To
properly determine the role of any given technique in the
care of the intubated patient, studies must account for the
possible effects of increased risk of infection inherent to
the technique. Such an approach has generally been lack-
ing in the respiratory and critical care literature. Even less
attention has been paid to techniques designed to prevent
or remove the biofilm. which should be an explicit goal of
airway clearance strategies for the intubated patient.

Goals of Airway Clearance Techniques
for the Intubated Patient

Our collective experience with care of intubated pa-
tients allows us to formulate several goals for airway clear-
ance techniques. Table 3 summarizes how these goals re-
late to the location, quality, and quantity of airway
secretions.

Prevent Catastrophic Obstruction of the
Endotracheal Tube

Death or disabilitv resulting from obstruction of an ETT
should he a rare event. Achieving this goal requires ad-
ilivssing the location of secretions: that is, ensuring they
do not accumulate in the ETT. Suctioning of the ETT and
airway humidification are the main techniques employed

810

Ri'SPiRATORV Care • July 2002 Vol 47 No 7

Airway Ci.f.arancf. Techniques for rm Paiiint wtiii an Ariii ici \i Airway

Table 3. Goals of Airway Clearance Tochnii|ues in Paiienis with
ArtiTicial Airways

Prevent catastrophic obstruction ol endotracheal tube (relates to

location of secretions)
Reduce peripheral airway obstruction

• Decrease work of breathing and inipro\c \cntilalion/pcrlusion
ratio (relates to quantity of secretionsi

Reduce infecti\ ity of secretions

• Bacterial quantit\ and antihimic resistance (relates to quality ol
secretions)

Table 4. Components of Airwa\ Clearance Strategies

Prevent mucus dehydration

Prevent upper airway and gastrouitcstuial tract colonization

Reduce supra-cuff secretion accuiiuilalion

Prevent aspiration around cull

Limit development of the bacterial hiofilni

Prevent disruption and aspiration of the biofilrn

Maintain patency of the central airway

Compensate for lack of natural cough

Compensate for reduced posture change

to achieve this goal. However, each of these techniques
iiitri)diiccs new prohlenis. which v\ili be discussed below.

Prevent or Reduce Peripheral .Airway Obstruction

Retained secretions in the distal airway.s increase airway
resistance and work of breathing. The.se effects are most
closely related to the quantity of secretions present in the
lung. Airway clearance techniques must therefore be ca-
pable of removing adequate quantities of secretions from
the airways.

Reduce Infectivity of Secretions

Secretions contaminated with infectious pathogens, re-
gardless of their quantity or location, will trigger an in-
tlammatory response leading to tissue injury or destruc-
tion. Airway clearance techniques therefore must address
the capability of secretions to initiate or escalate an in-
flammatory response.

Components of Airway Clearance Strategies

To meet the goals outlined above, airway clearance tech-
niques must accomplish the tasks listed in Table 4, which
are described in detail below.

Prevent Secretion Dehydration

This is achieved primaril) b\ ensuring humiditication
of the inspired air. Water vapor can be added to the in-

spired air with a heated humiiiit'ier. or water loss can be
prevented by the use of a heat and moisture exchanger
(HME).

The heated Initiiidii'icr is the most widely employed lech-
nic|iie lor Inimidifyiiig secretions. However, when used in
coiijunction with mechanical \ciuilaiors. water may accu-
mulate in the ventilator circuit or condense in the ETT and
be aspirated into the lung, introducing bacteria into the
lung. These bacteria may be exogenous contaminates of
the ventilator tubing or endogenous bacteria from the bio-
film in the ETT. ' '

The problem of condensate is avoided vsith an HME,
though humidification with an HME has tiot been shown
to be equivalent to that with a heated humidifier. Early
studies of HMEs suggest they may decrease,''' or at least
not increase" the risk of lower airway colonization and
VAP. However, some investigators have reported poten-
tially catastrophic obstruction of the ETT, especially when
an HME is used with a patient who produces e.xcessive
secretions. '" ' ^ Other studies have not reported similar prob-
lems, however."*

Another technique widely employed to hydrate and mo-
bilize mucus is regular instillation of small amounts of
normal saline into the ETT prior to suctioning. This prac-
tice is nearly universally employed in the care of intubated
patients, although data supporting its use are lacking. In 2
recent reviews, no evidence was found that routine saline
instillation provided any physiologic benefit, and in fact it
might contribute to hypoxemia.'"-" Hagler and Traver's"*
findings imply that saline instillation, by dislodging bac-
teria, can contribute to pulmonary inflammation and VAP.
though that hypothesis has not yet been confirmed clini-
cally.

Implications for Research. Variables such as the vol-
ume of secretions removed and blood gas values inay not
be the appropriate outcome measures for studying the short-
term effects of saline instillation. As well, no data have
been published on the effects of saline instillation on en-
dotracheal intubation hazards such as tube obstruction,
atelectasis, or VAP. Many studies of saline instillation
have included patients with minimal secretions, who are
unlikely to benefit from this technique. Although some
commentators have advocated abandoning saline instilla-
tion, to date no reports have been published indicating that
saline instillation can be abandoned without untoward ef-
fects.

Though evidence is lacking to support routine use of
normal saline instillation as a means of secretion removal
in the intubated patient, other solutions may ultimately
prove beneficial. For example, nasal irrigation with hyper-
tonic saline, but not normal saline, significantly improves
naso-sinus mucus clearance."' The effects of hypertonic
saline irrigation on lower airw ay mucus clearance deserves

Respiratory Carh • ivi,\ 2002 Vol 47 Nf) 7

811

Airway Ci.f.arancf. Tf.chniquhs fok tiii Patii;nt with an Artificial Airway

investigaticin. Furthermore, hypertonic saline (but not nor-
mal saline) aerosol therapy increases sputum expectora-
tion in cystic fibrosis patients, with no evidence of unto-
ward effects.-- Finally, hypertonic saline-soaked dressings
applied for brief periods to infected wounds of dialysis
patients speeds healing in patients with antibiotic-resistant
organisms.-' Could hypertonic saline instillation exert a
similar beneficial effect on the antibiotic-resistant ETT
biofilm?

Reduce I'pper Airway and Gastrointestinal Tract
Bacterial Colonization

Ventilator-associated pneiinmnia today is seldom the
result of primary inoculation of the lower airway with
exogenous pathogens. Rather. VAP typically results from
organisms that are first detectable in either the gastroin-
testinal tract or the oropharynx. Studies have suggested
that the pathogenic bacteria migrate from the upper gas-
trointestinal tract to the oropharynx, pool above the ETT
cuff, and are then aspirated into the lower airway.' "'-
The first step in this process may be partially the result of
aggressive strategies to reduce gastrointestinal bleeding in
the critically ill patient, through the use of proton pump
inhibitors or H-2 blockers. The resulting increase in gastric
pH favors the growth of pathogenic bacteria.--" In contrast,
providing gastric protection with sucralfate, which does
not alter gastric pH, decreases the risk of VAP.--*

Some investigators have attempted to prevent upper air-
way contamination by enteric organisms with the use of
prone positioning, which prevents or limits reflux of gas-
tric contents. One study of 86 patients found a lower rate
of VAP and mortality with prone positioning.-'^

The sinuses can be another bacteria reservoir, and sinus
bacterial contamination increases the risk of VAP. This is
especially true when nasotracheal tubes are used.-^-'' so
orotracheal intubation has been recommended as a means
to reduce nosocomial sinusitis.-'

Other mechanisms exist whereby the lower airway can
be contaminated with organisms from the upper airway.
The potential role of bacterial infection of the dental struc-
tures in intubated patients has recently been explored. Four-
rier et al-** prospectively evaluated the amount of dental
plaque present in intubated ICU patients. The amount of
dental plaque increased significantly during the ICU stay,
as did the amount and variety of oral pathogens. Coloni-
zation of plaque with pathogenic bacteria was highly cor-
related with the development of VAP and bacteremia.

Implications for Research. The finding that coloniza-
tion or infection of the sinuses and dental structures ma\
contribute to VAP suggests that the overall question of
care of the nasal passages, oral cavity, and sinuses in the

intubated patient should be more widely addressed. For
example, should suction catheters, once used to suction the
ETT or lower airway, be used to suction the nares? Classic
teachings in respiratory care stress that catheters used in
the nasopharynx or oropharynx should not be used to suc-
tion the lower airway. However, the reverse practice is
generally accepted. v\hich may introduce microorganisms
from the ETT that are not yet present in large numbers in
other parts of the airway. These organisms can multiply in
the sinuses or dental structures of an immunocompromised
patient, leading to sepsis and creating a reservoir for in-
fection or re-infection of the lower airway.

The potential benefit of pre\enting or treating sinusitis
in the intubated patient is suggested by a study by Holz-
aplcl et al. who observed a 20% decrease in mortality
among ventilated patients when a protocol for identifica-
tion and treatment of sinusitis was implemented.-''

Oral hygiene is difficult in the orally intubated, criti-
cally ill patient. At best, care is limited to superficial cleans-
ing with soft sponge-type brushes. More vigorous means
of dental hygiene are difficult to use. However, in theory,
reduction of oropharyngeal bacterial load, through more
vigorous methods of dental hygiene aimed at deep clean-
ing, may prove beneficial in reducing sources of infection.
The efficacy of incorporating dental hygienists. at least in
a consultative capacity, in the care of \entilated patients
warrants study.

Prevent Secretion Accumulation above the
Endotracheal Tube Cuff

Secretions easily accumulate in the space abo\e the ETT
cuff. Radiologic studies suggest that up to 10 niL may be
present at any time,'" and aspiration of small amounts into
the lower airway is unavoidable with conventional ETTs
and cuffs." The Hi-Lo Evac tube (Nellcor Puritan Ben-
nett/Tyco Healthcare. Pleasanton. California) is designed
to address this problem; it has a suction port open to the
area where secretions accumulate (Fig. 2) and through
which secretions can be continuously or intermittently as-
pirated. Trials with this tube show that it reduces the risk
of VAP."'-'2-'-'

Implications for Research. Trials of continuous subglot-
tic secretion aspiration need to be extended to larger and
more diverse groups. An additional method that may pro\e
useful in preventing accumulation of secretions in the su-
pra-cuff space is suggested by a case study, reported by
Fung et al. of removal of a foreign body in the airway. ■'•'
They successfully removed an aspirated tooth that was
lodged outside the ETT at the level of the cuff, by deflat-
ing the cuff dining manual hyperinfiation. This resulted in
increased cephalad air fiow past the cuff, which carried the
aspirated tooth to the pharynx, where it was remo\ed. In

812

Re.spir VTORY Care • Jll'i- 2002 Vof 47 No 7

Airway Ci.faranci: Tkchniquks ior tiii Patiivi with w Aurii iciai Airway

Fig. 2. Hi-Lo Evac endotracheal tube (Nellcor Puritan Bennett/
Tyco Healthcare. Pleasanton, California). The suction port allows
suctioning secretions that pool above the cuff. (Courtesy of Nell-
cor Puritan Bennett)

theory, this approach would also result in cephalad move-
ment of secretions From the supra-cutf space to the oro-
pharynx, for easy removal. Such an approach deserves a
trial in a clinical setting.

Prevent Aspiration of Secretions from the Supra-
Cuff Space

If accumulation of secretions abo\e the cuff cannot be
prevented, then efforts to prevent their aspiration may be
helpful. Maintaining cuff pressure at 20 mm Hg signifi-
cantly reduces the risk of aspiration.'' However, the long-
term safety of this technique, especially in hypotensive
patients, is unknown.

Another technique of interest was presented by Blunt et
al.'^ With an in vitro model they demonstrated that lubri-
cating the ETT cuff with a water-soluble gel prt)duces an
effective mechanical barrier to aspiration. It is unclear if
this technique can be applied to patients who arc intubated
long-term.

Other investigators ha\c explored ihc characteristics of
the ETT cuff itselt in preventing or promoting aspiration.

liiflalion of a I'loppy. large-volume, low-pressure cuff re-
sults in the formation of channels between the cuff and the
tracheal wall, through which aspiration of secretions oc-
curs. '" Elimination of those channels by cuff inllation pres-
sure of 2()-.'^() mm Hg and the use of cuffs designed to
prevent the creation of channels reduce the possibility of
aspiration," but iho.sc studies diil not address the potential
for tracheal wall damage.

Iniplication.s for Research. Endotracheal suclionmg in-
creases the pressure gradient between supra-cuff pooled
secretions and the lower airway and thus might increase
the risk of aspiration around the cuff. Documentation of
this in vivo would help to clarify the risks and benefits of
suctioning, and perhaps encourage the development of ETT
cuffs that limit the risk of aspiration.

Prevent Deveh)pnient of Biofllm

Either chemical or mechanical means could, in theory,
be employed to prevent the development of the biofilm in
the ETT. Preliminary studies showed that impregnating or
coating the ETT with silver inhibits bacterial growth.'*

Trawoger et af' reported success in preventing biofilm
in an animal model, using intratracheal pulmonary venti-
lation. This technique requires an ETT that has a lumen
incorporated into the wall of the tube and through which
saline can be flushed on a continuous basis. The opening
of this channel directs the saline cephalad (Fig. 3). They
found that use of this technique in animals prevented the
development of the biofilm and also eliminated the need
for suctioning.

Implications for Research. Mechanical techniques, such
as brushing or scraping the internal lumen of the ETT,
with the aim of preventing or removing the biofilm. should
be "bench tested" and subjected to clinical trials. Like-
wise, continuous Hushing of the ETT with saline, as de-
scribed in the study by Trawoger et al.''' should be studied
in humans.

Prevent Disruption and Aspiration of the Biotllm

If development of the biofilm cannot be prevented, then
at least attempts should be made to prevent its disruption
and consequent aspiration. Suctioning and saline instilla-
tion can dislodge antibiotic-resistant bacteria into the air-
way.'* but these techniques are universally einployed in
both adult and pediatric ICUs. which undoubtedly has con-
sequences for the critically ill patient. Even if pneumonia
is avoided, bacterial colonization can peipetuate infiam-
matioii and delay recovery.

Respiratory Care • July 2002 Vol 47 No 7

813

Airway Clearance Techniques fcir tiii Patient with an Artimcial Airway

Liquefieo mucus

Fig. 3. Transport of mucus deposits in in vitro experiments. A.
Infused saline is dispersed into small droplets, exiting ttie reverse-
thrust catheter. B. Saline droplets form a thin layer of liquid on the
inner surface of the endotracheal tube (ETT). C. The layer of saline
is transported cephalad by the intratracheal pulmonary ventilation
gas flow. A small sample of mucus is introduced at the tip of the
ETT. D. Mucus is liquified and transported cephalad together with
the saline. Mucus and saline are expelled from the ETT. (From
Reference 39. with permission.)

Can chest wall percussion, when used to dislodiie mucus
from the airways, also loosen the biot'ilm?

Maintain Patency of the Central Airway

Mucus accumulaiion with partial or complete plugging
of the ETT can occur despite meticulous attention to hu-
miditication and routine suctioning with either open or
closed suction systems.'" This phenomenon has not been
systematically explored, but it is usually attributed to in-
adequate humidification.

A recent report suggests that the incidence of tube oc-
clusion may be increasing and may be related to the use of
HMEs.'" Reports on the safety of HMEs are conflicting.
The risk of tube occlusion with HMEs may be inediated by
host factors such as the magnitude of ongoing inflainma-
tion processes in the airway and the volume of .secretions.
Other aspects of patient care, such as systemic hydration,
undoubtedly play a role as well.

Partial or complete obstruction of an ETT can be rem-
edied by replacing the tube, but this is not always possible.
Emergency restoration of patency, using a balloon-tipped
arterial embolectomy catheter, has been reported in a pa-
tient in whom reintubation was considered hazardous.-"'
Since reintubation is a known risk factor for VAP,-" more
widespread use of that technique may limit the develop-
ment of VAP.

Implications tor Research. Fear of ETT occlusion prob-
ably prompts much of the routine suctioning and saline
instillation in the ICU. If these practices are to be ratio-
nali/ed. caretakers must be con\inced that restriction of
these procedures in the ICU will not increase the risk of
tube obstruction. Clarifying the etiology of ETT obstruc-
tion will help in the formulation of novel strategies for
maintaining airway patency.

Compensate for Lacli of Normal Cough

Implications for Research. Studies are needed to exam-
ine the effects of eliminating routine saline instillation as
part of the suctioning procedure, as well as trials of re-
ducing the frequency of suctioning.

Given the finding that passage of a suction catheter
dislodges bacteria into the airway, the common teaching
that suction should be applied only when withdrawing the
catheter should be reconsidered. Could applying suction
while inserting the catheter result in removal of the dis-
lodged fragments of the biofilm? The possible role of other
procedures in disruption and aspiration of the biofilm should
also be explored. Does mo\ing the patient from side to
side cause movement of the liTT and biofilm disruption?

An intubated patient is unable to cough effectively, ei-
ther because of the presence of the ETT or because of the
illnesses necessitating the tube's use. This may be the
result of inability to take and hold a deep breath, inability
to close the glottis, and/or inability to forcibly exhale.
Compensatory actions include provision of a deep breath
(manual hyperinflation), simulation of glottic closure (in-
flation hold), and assisted expiration (chest or abdominal
wall compression).

Manual hy|ierinflation (bagging, coupled with an in-
spiratory hold and unobstructed expiration) is employed to
simulate a cough in intubated patients. Only recently have
serious efforts been made to demonstrate the utility of this
technique. Ntoumenopoulus et aP- showed that VAP can
be delayed or reduced by employing such techniques in

814

Re.spiraiorv Cari:« JiLV 2002 Vol. 47 No 7

Airway Clearance Techniques for the Patient with an Artiiiciai Airway

trauma patients. A study with chiklrcn ilcmtnistratecl rapiti
iiiipro\onicnl in atelectasis \\ hen manual inflation was useil
in conjunction w ith saline instillation and chest wall com-
pression i>n exhalalion."

Manual liyperinnation m.iN he hazardous in certain pa-
tients, however, such as those with intracranial hyperten-
sion or severely reduced linij; compliance.""

Endotracheal suctioning; can also be conceived of as a
technique to compensate for lack of elTective cough. En-
dotracheal suctioning removes secretiims from the central
airways, so most research has focused on reducing hazards
associated with endotracheal suctioning, rather than on
improving the volume ol secretions removed. Early re-
search on the ICU application of suctioning focused on its
effects on acute cardiopulmonary changes. A full review
of those studies is beyond the scope of this review, but it
is clear that closed suction systems are superior to open
systems in this regard.-*^ Furthermore, some studies sug-
gest that closed suction systems may be superior to open
systems in preventing VAP."*" The most obvious explana-
tion is that the closed system's catheter is less likely to be
contaminated by bacteria from the environment. However,
other factors, such as less motion of the ventilator tubing
(and spillage of condensate), may be important as well.
Using closed suction systems for se\ eral days before chang-
ing trather than daily changes) has not been shown to
increase the risk of VAP.-*^ The reuse of conventional
catheters for up to 24 hours was found to be safe in a
limited study in a pediatric ICU.^**

Another approach to limiting hazards associated with
suctioning is to limit the frequency of suctioning. Two
studies from neonatal ICUs have addressed this approach.
Both found that the frequency of routine suctioning could
be reduced from every 4 hours to every 8 hoiu's without
untoward effects.^'' '^" Similar studies from adult ICUs have
not been published.

Endotracheal suctioning can also directly damage the
bronchial mucosa. Newborns appear to be especially vul-
nerable to mucosal damage, with bronchial stenosis devel-
oping in some patients as a result.^' Using an animal model.
Bailey et aP- demonstrated that mucosal damage could
be eliminated by not inserting the catheter beyond the tip
of the ETT. That finding prompted many neonatal ICUs to
modify suctioning techniques. However, there are no pub-
lished data establishing that limiting suctioning in this fash-
ion does not increase the risk of tube obstruction.

Limiting suction pressure is commonly recommended
to avoid damaging the bronchial mucosa. Recently. Kapur
et al-'^'' demonstrated that routine use of suction pressures in
excess of -140 mm Hg greatly increases the incidence of
mucosal injury.

In part to prevent hypoxemia, it is commonly recom-
mended that the ratio of the outside diameter of the suction
catheter to the inside diameter of the ETT be ^ 0.5. How-

ever. .Singh el al.'^' in a study of intubated chiklren. found
that increasing that ratio to 0.7 resulteil in greater secretion
removal, without ailverse canliovascular changes. The ef-
fects on mucosal liauma anil risk of infection were not
studieil.

Direct aspiration of secretions can also be accomplished
by rigid or llexible bronchoscopy. A rigid bronchoscope is
more efficient at suctioning secretions but less useful in
treating obstructions of ilie upper lobes. Conversely, flex-
ible bronchoscopes can be maneuvered to reach a larger
nmiiber of airways but hav e smaller and less efficient suc-
tion channels. ^"^ Bronchoscopy may be especially useful
following airway surgery, when blind suctioning may dis-
rupt sutures.

Compensate for Lack of Spontaneous Position
Change

Critically ill patients with ETTs are often unable to
move spontaneously, as a result of either their illness or
therapy. Humans partly rely on spontaneous position change
to maintain airway clearance, so when a patient cannot
move spontaneously, secretion retention results. Periodic
position change is a standard of patient care but is very
labor intensive and can result in injury to health care per-
sonnel. Automated devices for changing patient position
would therefore seem to be useful, and could result in
more frequent and more pronounced position changes.

Kinetic therapy (or automatic lateral rotation) is the term
used to describe the use of a special bed that periodically
rotates (40 degrees or more) from side to side. This device
reduces the risk of and aids in the resolution of atelectasis
in both intubated and noninlubated patients.^''

Summary

Biological changes associated with the use of artificial
airways require the ICU team to employ techniques to
prevent or alleviate secretion accumulation. These tech-
niques are usually evaluated by their effects on the volume
of secretions removed or on their immediate effects on
pulmonary function, but that approach ignores the poten-
tial for these techniques to cause airway infection and
inflammation. Conclusions regarding the proper applica-
tion of airway clearance techniques can only be ba.sed on
studies that employ broad outcome measures, such as VAP
rate, mortality, and resource utilization.

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Respir.atory Care • Ji ly 2002 Vol 47 No 7

817

The Pharmacologic Approach to Airway Clearance:

Mucoactive Agents

Bruce K Rubin MEngr MD FAARC

Introduction
Kxpectorants
Medications That Change the Biophysical Properties of Secretions

Mucolytics
Mucokinetic Agents
Cough Clearance Promoters
Mucoregulatory Medications
Summary

The airway mucosa responds to infection and inflammation in a variety of ways. This response often
includes surface mucous (goblet) cell and submucosal gland hyperplasia and hypertrophy, with
mucus hypersecretion. Products of inflammation, including ncutrophil-derived deoxyribonucleic
acid (DNA) and filamentous actin (F-actin), effete cells, bacteria, and cell debris, all contribute to
mucus purulence and. when this mucus is expectorated it is called sputum. Mucoactive medications
are intended to serve one of 2 purposes; either to increase the ability to expectorate sputum or to
decrease mucus hypersecretion. Mucoactive medications have been classified according to their
proposed mechanisms of action. Increased knowledge of the properties of mucus has given us tools
to better understand the mechanisms of airway disease and mucoactive therapy. Expectorants are
thought to increase the volume or hydration of airway secretions. Systemic hydration and classic
expectorants have not been demonstrated to be clinically effective. Modifiers of airway water trans-
port are being clinically investigated as expectorants. Mucolytics degrade polymers in secretions.
The classic mucolytics have free thiol groups to degrade mucin. Peptide mucolytics break pathologic
filaments of neutrophil-derived DNA and actin in sputum. Nondestructive mucolysis includes mucin
dispersion by means of charge shielding. Mucokinetics are medications that increase mucociliary
efficiency or cough efficiency. Cough flow can be increased by bronchodilators in patients with
airway hyperreactivity. Ahhesives such as surfactants decrease mucus attachment to the cilia and
epithelium, augmenting both cough and mucociliary clearance. Mucoregulatory agents reduce the
volume of airway mucus secretion and appear to be especially effective in hypersecretory states such
as bronchorrhea, diffuse panbronchiolitis, and some forms of asthma. Mucoregulatory agents
include anti-injlammatory agents (indomethacin. glucocorticosteroids), anticholinergic agents, and
some macrolide antibiotics. Classifying mucoactive agents should help us to develop and evaluate
new types of therapy and to better direct therap> tow ard the patients who are most likely to benefit.
Kc\ words: muvocuiivc nicdiidlioiis. cxpectdidiits. iniicolrliis. niucdkiiiaiis. muc<irci;iilcitiir\ niciliici-
lions. nuicroUdes, surfactants, ahhesives. ion transport. coiti;h. mncociUury clearance, cystic fibrosis,
chronic Ivoncliitis. (Respir Care 2()02;47(7):81<S-S22]

818 Respiratory Care • July 2002 Vol 47 No 7

Thk Pharmacoi ouic Approach to A\lR\vA^ Ci.iarance: MucoArrivF, Agents

Introduction

The air\\ii> iinicosa ivspniKls to intcdioii and inriam-
ination in a variety ot ways. Tiiis response often iiieliRles
surface mucous (goblet) cell and submucosal gland hyper-
plasia and hypertrophy, with mucus hypersecretion. Prod-
ucts of inflammation (including neulrophil-derived de-
oxyribonucleic acid |DNA| and filamentous actin |F-actin|.
effete cells, bacteria, and cell debris) all contribute to mu-
cus purulcncc, and when this mucus is expectorated it is
called sputum. Mucoactive medications are intended to
serve one of 2 purposes; either to increase the ability to
expectorate sputum or to decrease mucus hypersecretion.
Mucoactive medications have been classified according to
their proposed mechanisms of action (Table 1).' In this
review I discuss each of these classes of medication, their
proposed mechanisms of action, and their potential uses in
treating chronic airways diseases associated with poor mu-
cus clearance and mucus hypersecretion.

Expectorants

Expectorants are medications taken to improve the abil-
ity to expectorate purulent secretions. The term expecto-
rants is now taken to mean medications that increase air-
way water or the volume of airway secretions. The most
commonly used expectorants are simple hydration (includ-
ing both hland aerosol administration and oral hydration),
iodide-containing compounds such as SSKI (saturated so-
lution of potassium iodine) or iodinated glycerol, glyceryl
guaiacolate (guaifenesin), and the more recently devel-
oped ion channel modifiers such as the P2Y2 purinergic
agonists. Most of these are ineffective at adding water
to the airway, and those that are effective are also mu-
cus secretagogues. increasing the volume of both mucus
and water in the airways. Despite widespread use, io-
dinated compounds, guaifenesin, and simple hydration
are ineffective as expectorants.- In fact over-hydration
has been shown to decrease airway mucus clearance in
some patients with chronic airway disease, particularly
those with acute asthma.'

Hyperosmolar saline aerosol or dry-powder mannitol
inhalation has been used for sputum induction, and there

Table I. Mucoactive Agents

Mucoactive Agent

Possible Mechanism of Action

Bruce K Rubin MEngr MD F.AARC is affiliated with tlic Department of
Pediatrics. Wal<c Forest University School ot Medicine. Winston-Salem,
North Carolina.

Dr Rubin presented a version of this report at the 17th Annual New
Horizons Symposium at the 47th International Respiratory Congress. San
Antonio. Texas, December 14. 2001.

Correspondence: Bruce K Rubin MEiigr MD FAARC. Department of
Pediatrics. Wake Forest Universitv School of Medicine. Medical Center
Boulevard. Winston-Salem NC 27l.'i7-l08l. E-mail: bnjbintS'wtubmc.edu.

Hypertonic saline

Chiwiciil nimolytics
N-acctylcysteine

Nacystelyn

Fi'lHiile mmolyuci
Dornase alfa

Gelsolin or Thymosin fi4

Non-desniuiivc inuLolytics
Dextran

Low molecular weight
heparin

Mucore^tilaloiy agenls
Anticholinergic agents

Glucocorticoids

Indomethacin
Macrolide antibiotics

Cininh clciiraiuc promoters
Bronchodilators

Surfactants

Increases secretion \olume and
perhaps hydration

Severs disullide bond linking

mucin oligomers
Increases chloride secretion and

severs liisuHide bonds

Hydroly/es DNA polymer with

reduction in DNA length
Depolymeri/.es F-actin

Breaks hydrogen bonds and
increases secretion hydration

May break both hydrogen and ionic
bonds

Decrea.ses volume of stimulated

secretions
Decreases airway innammalion and

mucin secretion
Decreases airway inflammation
Decreases airway inflammation and

mucin secretion

Can improve cough clearance by

increasing expiratory flow
Decreases sputum adhesivity

DN.^ - deoxyribonucleic .icid

are some data that suggest that the.se may also promote
airway mucus clearance in patients with chronic airway
disease.-'-'^

Agents that increase transport across ion channels, such
as the cystic fibrosis transmembrane ion regulator (CFTR)
chloride channel, calcium-dependent chloride channel, or
agents that increase water transport across the airway aqua-
porin water channels may increase the hydration of the
periciliary fluid and st) may aid expectoration. These med-
ications (including gene transfer vectors) are actively be-
ing investigated. Early results from studies using uri-
dine triphosphate (UTP) to stimulate chloride secretion
or amiloride to block epithelial sodium channels were
disappointing in that these agents did not produce sus-
tained improveinent in pulmonary function in persons
with cystic fibrosis (CF).''

In general, expectorant medications have not been con-
sistently demonstrated to be effective for the treatment of
any acute or chronic airway disease associated with mucus
stasis or hypersecretion.

Respiratory Care • July 2002 Vol 47 No 7

819

The Pharmacologic Approach to Airway Ciharance: Mucoactive Agents

Medications That Chaiifit' the biophysical Properties
of Secretions

The principal polymer component of normal airway mu-
cus is mucin glycoprotein. The mucin protein is heavily
decorated with oligosaccharide side chains, and the elon-
gated glycoproteins linearly polymerize and form a "tan-
gled network" secondary structure. This accounts for the
gel structure of normal airway mucus. With chronic in-
tlammation there is thought to be hypersecretion of mucin,
although this has not been proven.^ In addition, a second-
ary polymer network composed of neutrophil-deri ved DN A
and F-actin also forms within the airway. This DNA forms
rigid polymer chains that copolymerize with cell-wall-as-
sociated actin.** This secondary polymer network is prob-
ably responsible for many of the abnormal properties of
purulent secretions.

Mucolytics

Mucolytic medications depolymerize either the mucin
network (classic mucolytics) or the DNA-actin polymer
network (peptide mucolytics) and in so doing reduce the
viscosity and elasticity of airway secretions. Mucus has
viscoelastic properties of both liquids (viscosity) and sol-
ids (elasticity). Thus it is a gel, and both the viscous (en-
ergy loss) and elastic (energy storage) properties are es-
sential for mucus spreading and clearance." Mucociliary
clearance appears to be dependent upon there being an
optimal ratio of viscosity to elasticity. Mucolytic agents
have the potential to improve mucus rheology, thus im-
proving mucociliary or cough clearance, but these medi-
cations are also potentially able to over-liquify secretions
and thus decrease clearance.'"

Classic Mucolytics. Classic mucolytics depolymerize
the mucin glycoprotein oligomers by hydrolyzing the di-
sulfide bonds that link the mucin monomers. This is usu-
ally accomplished by free thiol (sullhydryl) groups hydro-
lyzing disulfide bonds attached to cysteine residues of the
protein core. The best known of these agents is N-acetyl
L-cysteine (NAC), which is widely used to treat chronic
bronchitis in Europe and Asia. There are few data avail-
able from placebo-controlled clinical trials of NAC or its
derivatives, and the available data do not clearly demon-
strate that NAC improves mucus clearance or pulmonary
function." NAC aerosol is available in the United States
but is often poorly tolerated by patients because of its
sulfurous odor and because its low pH (2.2) is associated
with bronchospasm. NAC is an antioxidant and has been
used to treat acetaminophen overdose. The oral compound
is also available in Europe, but. despite being a potent
anti-oxidant. few data indicate that this medication is ef-
fective in the treatment of chronic airway di.sease.

Fig. 1 . Laser scanning confocal microscope image of cystic fibro-
sis sputum abundant in long filaments of deoxyribonucleic acid
(DNA) stained witfi Yoyo-1. Initially prominent DNA polymer fila-
ments (left) are degraded by dornase alfa treatment in vitro (right).
(From Reference 7. with permission.)

There are a number of similar compounds containing
sulfhydryl groups that effectively depolymerize mucin
polymers in vitro. Although many of these are better tol-
erated than NAC. none have been clearly demonstrated to
improve mucus clearance.

Peptide Mucolytics. The mucin polyiner network is es-
sential for normal mucus clearance. It may be that the
classic mucolytics are generally ineffective because they
are depolymerizing essential components of the mucous
gel. With airway intlammation and intlammatory cell ne-
crosis, a secondary polymer network develops in purulent
secretions. In contrast to the mucin network, this patho-
logic polymer gel serves no obvious purpose in airway
protection or mucus clearance. The peptide mucolytics are
designed specifically to depolymerize the DNA polymer
(dornase alfa) or the F-actin network (eg. gelsolin. thymo-
.sin i34) (Fig. 1).

Dornase alfa has seen wide acceptance as a peptide
mucolytic tor the treatment of CF airway disease.'- When
used as prescribed its use is associated with improved
pulmonary function, decreased antibiotic use. and de-
creased hospitalization rate for many patients with CF.'"*
For reasons that are not clear, this medication is not luii-
formly effective for the treatment of CF airway disease,
and efficacy does not seein to be related to sputum DNA
content in persons with CF. There are limited and anec-
dotal data suggesting that dornase alfa may be effective in
treating .some persons with non-CF bronchiectasis, includ-
ing some patients with priinary ciliary dyskinesia. '■^ Al-
though dornase alfa was not effective for the therapy of
severe chronic bronchitis, there are no published studies
evaluating its potential efficacy in patients with milder
disease.

Both gelsolin and thymosin fi4 have been demonstrated
to depolymerize the pathologic DNA/F-actin network in

820

Re.spirator'c Care • ]vl\ 2002 Vol 47 No 7

The Pharmacologic Approach to Airway Ci.farancf,: Mucoactivi- Agents

CF sputum, but these agents have not been studied in
controlled chnieai trials.

Nondestructive Mucolytics. Muein is a polyionie tan-
gled net\M>rk. and the charged naline of the oligosaecha-
ride side chains helps to hold this network tiigether as a
gel. Several agents ha\e been proposed that can "loosen"
this network by charge shielding. These agents include
low -molecular-weight dextran, heparin, and other sugars
or glycoproteins.'-'^

Mucokinetic Agents

A mucokinetic medication is a drug that increases mu-
cociliary clearance, generally by acting on the cilia. Al-
though a variety of medications, such as tricyclic nucleo-
tides. (5 agonist bronchodilators. and methylxanthine
bronchodilators. have been demonstrated to increase cili-
ary beat frequency, these agents have only a minimal ef-
fect on mucociliary clearance in patients with lung dis-
ease.'* The reason for this is probably a combination of
factors, including the limited potential for efficacy in an
airway with dysfunctional cilia or denuded of cilia. Most
of these agents are also mucus secretagogues, which may,
paradoxically, increase the burden of airway secretions.
Bronchodilator medications can also increa.se airway col-
lapse in patients with bronchomalacia by virtue of their
ability to relax airway smooth muscle. Therefore, the only
persons for whom these medications are recommended are
those who have improved expiratory air tlow following
their use. Increased expiratory air flow can substantially
contribute to the effectiveness of cough. '^ Thus, broncho-
dilators might be better considered cough clearance pro-
motors, as described below.

Cough Clearance Promoters

Cough becomes a major mechanism for mucus clear-
ance when there is extensive ciliary damage and mucus
hypersecretion. Cough clearance depends on expiratory air
flow, volume, and force, and the biophysical properties of
airway secretions. In general, decreasing the viscoelastic-
ity of airway secretions will not improve cough clearance
unless this therapy also releases mucus from adherent en-
tanglements w ith cilia. As mucus becomes adherent to the
epithelium, it becomes far more difficult to expectorate.
Patients who appear to benefit from expectorants or mu-
colytic agents may do so by virtue of these medications
releasing mucus from epithelial attachment.

Agents that reduce the adhesivity of airway secretions
and thus reduce binding to the epithelium are the abhe-
sives. There is a thin layer of surfactant that separates the
periciliary fluid and the cilia from the mucus layer, per-
mitting effective ciliary function and preventing secretion

adherence to the epithelium. With airway inllammalion
there is extensive surfactant hydrolysis by secretory phos-
pholipases A2 (sPLA2) and the generation of lyso-phos-
pholipids ihal appear to increase mucus adhesivity."* It has
been shown thai aerosolized surfactants are effective ab-
hesives and can significantly improve both cough clear-
ability of secretions anil pulmonary function in |iatienls
with chronic bronchitis.'''

Earlier generations of air-entrainment-driven Jet nebu-
lizers made it difficult to efficiently aerosolize surfactant.
as this medication foams extensively and coals surfaces.
Newer aerosol delivery devices permit surfactant to be
administered efficiently either as a dry powder or as a wet
aerosol. .Studies are planned to evaluate surfactant for pa-
tients with chronic airway diseases, using these newer
modes of surfactant delivery.

Mucoregulatory Medications

Another approach to reducing the burden of airway se-
cretions is to decrease hypersecretion by goblet cells and
submucosal glands. Medications that decrease inucus hy-
persecretion, but not below the baseline .secretion rate, are
referred to as mucoregulatory medications. These include
anti-intlammatory drugs such as corticosteroids, which are
effective at decreasing the inflammatory stimulus that leads
to mucus hypersecretion. Aerosolized indomethacin has
also been used in Japan to treat patients with diffuse pan-
bronchiolitis. who have impairment due to mucus hyper-
secretion.-"

Anticholinergic medications are also extensively used
as mucoregulatory medications. Atropine is routinely given
peri-operatively to prevent laryngospasm and to decrea.se
mucus secretion associated with endotracheal intubation.
Atropine and its derivatives are mucoregulatory medica-
tions in that they do not "dry" secretions but will decrease
hypersecretion that is mediated through M3 cholinergic
mechanisms. The quaternary ammonium derivatives of at-
ropine, including ipratropiinii bromide and oxitropium bro-
mide, do not substantially cross the blood-airway barrier
and so their use is not associated with typical systemic
effects of anticholinergic medications such as flushing and
tachycardia. Ipratropium bromide is widely used as a bron-
chodilator medication in patients with chronic bronchitis.
Studies have also shown that the long-term use of ipratro-
pium is associated with a reduction in the volume of mu-
cus secretion in patients with chronic bronchitis.-' More
specific M3 antagonists hold the promise of improved mu-
coregulatoiy efficacy from this class of medications, with
less risk of ad\erse effects.

Some of the more interesting of the mucoregulatory
medications are the macrolide antibiotics. These antibiot-
ics were discovered 50 years ago. and derivatives of eryth-
romvcin A have been widelv used to treat bacterial infec-

Respirator">- Care • July 2002 Vol 47 No 7

821

The Pharmacologic Approach io Airway Clearance: Mucoactive Agents

tidti. Since the mid-1960s, diila ha\e been accumulating
that these medications also ha\e iminunoniodulatory prop-
erties. This means that they decrease hyperimmunity or
inllammation to more normal ami beneficial levels. The
mechanism of these properties appears to be ditt'erent from
that of the corticosteroids. These immunomodulatory and
mucoregulatory properties of macrolide antibiotics have
been exploited for the treatment ot diffuse panbronchiol-
itis. a chronic inflammatory airway disease with great mor-
bidity and nuirtality when untreated. Diffuse panbronchi-
olitis is primarily seen in Japan and Korea, hs etiolog) is
unknovv n. but the disease results in chronic sinobronchitis
with mucus hypersecretion and debilitation. Antibiotics
and corticosteroids are ineffective for the treatment of dif-
fuse panbronchiolitis. By virtue of their immunomodula-
tory and mucoregulatory properties, the macrolide antibi-
otics are the most effective agents for the treatment of
diffuse panbronchiolitis. Accumulating evidence suggests
that the 14- and l.'^-member inacrolides. but not the 16-
meniber inacrolides. may also be highly effective for the
treatment of CF airway disease.

The mucoregulatory mechanism of the macrolides is
under intensive study.---' and it is anticipated that the
development of macrolide medications without antibiotic
properties will substantially extend the spectrum of use of
these medications.

Summary

Airway mucus hypersecretion and mucus retention is a
substantial problem for the patient with chronic airway
disease. The burden of asthma, chronic bronchitis, bron-
chiectasis, CF, and other airway diseases poses one of the
most important public health problems internationally.
Medications that can effectively improve mucus clearance
would provide relief to millions of people around the world.
Although many medications have been used clinically as
mucoactive therapy, there are few data to support any but
a handful of these medications. This is a subject of ongo-
ing investigation and rapid change.

REFERENCES

1. Rubin BK. Tomkiewicz RP. King M. Mucoactive agents: old and
new. In: Wilmolt RW. editor. The pediatric lung. Basel: Birkhauser
Publishing: I997:15.'i-I79.

2. Jager EG. Double-blind, placebo-controlled clinical evaluation of
guaimesal in oulpalicnls. Clin Tliera 198^:1 l(.^):.WI-.%2.

?. Shim C. King M. Williams MH Jr. Lack of effect of hydration on
sputum production in chronic bronchitis. Chest mS7:92(4):679-<S82.

4. Eng PA. Morion J. Douglass JA. Riedler J. Wilson J. Robenson CF.
-Short-term efficacy of ultrasonically nebulized hypertonic saline in
cystic fibrosis. Pediatr Pulmon 1996:2 1 (2):77-8.1.

5. Daviskas E. Anderson SD. Brannan JD, Chan HK, Eberl S, Bautov-
ich G. Inhalation of dry-powder mannilol increases mucociliary clear-
ance. Eur Rcspir .1 I997;l(l( 1 1 ):2449-24.'i4.

b. Graham A. Hashani A. Alton EW. Martin GP. Marriott C. Hodson
ME. Clarke SW. Geddes DM. No added benefit from nebulized
amilohde in patients with cystic fibrosis. Eur Rcspir J 199.^:6(9);
124.V1248.

7. Tomkiewicz RP. Kishioka C. Freeman J. Rubin BK. DNA and aclin
filament ullrastructure in cystic fibrosis sputum. In: Bauni G. editor.
Cilia, mucus and mucociliary interactions. New York: Marcel Dek-
ker: 199S:3.W-UI.

8. King M. Rubin BK. Mucus rheology: relationship with transport. In:
Takishima T. Airway secretion: physiological bases for the control
of mucus hypersecretion. New York: Marcel Dekker; 1994:283-314.

9. Puchelle E. Zahm JM. Girard F. Bertrand A. Polu JM. Aug F. Sadoul
P. Mucociliary transport in vivo and in vilro: relations to sputum
properties in chronic bronchitis. Eur J Respir Dis 19S():bl(5):254-
264,

10. Rubin BK. MacLeod PM. Sturgess J. King M. Recurrent respiratory
infections in a child with fucosidosis. Is the mucus too thin for
effective transport' Pediatr Pulmonol 199l;10(4):304-.3()9.

I I. Giandjean EM. Berthet P. Ruffmann R. Leuenberger P. Efficacy of
oral long-term N-acetylc\steine in chronic bronchopulmonary dis-
ease: a meta-analysis of published double-blind, placebo-controlled
clinical trials. Clin Ther 2000:22(2):209-221.

12. Laube BL. Auci RM. Shields DE. Christiansen DH. Lucas MK.
Fuchs HJ. Rosenstein DH. Effect of rhDNase on airflow obstruction
and mucociliary clearance in cystic fibrosis. Am J Respir Crit Care
Med l996;l53(2):752-760.

13. Fuchs HJ. Borowilz DS. Christiansen DH. Morris EM. Nash ML.
Ramsey BW. Rosenstein BJ. Smith AL. Wohl ME. Effect of aero-
solized recombinant human DNase on exacerbations of respiratory-
symptoms and on pulmonary function in patients with cystic fibrosis.
The Pulmozyme Study Group. N Engl J Med 1994:33 1 ( I0):6.37-
642.

14. Rubin BK. Who will benefit from DNase'.' Pediatric Pulmonol 1999;
27(l):3-t.

15. Feng W, Garrett H. Speen DP. King M. Improved clearability of
cystic fibrosis sputum with de.\tran treatment in \itro. Am J Respir
Crit Care Med I998;l.s7(3 Pt 11:710-714.

16. Isawa T. Teshima T. Hirano T. Ebina A. Konno K. Effect of oral
salbutamol on mucociliary clearance mechanisms in the lungs. To-
hoku J Exp Med I986;l.'i0( I ):.sl-61.

17. King M, Brock G. Lundell C. Clearance of mucus by simulated
cough. J AppI Physiol I98.'i:.'i8(6):l776-I782.

18. Hite RD. Seeds MC. Jacinto RB. Balasubramanian R. Waite M. Bass
D. Hydrolysis of surfactant-associated phosphotid) Icholine by mam-
malian secretory phospholipases .\2. .Am J Physiol 1998:275 (4 Pt
I ):L74()^L747.

19. Anzueto A. Jubran A. Ohar JA. Piquette C.A. Rennard SI. Colice G.
at al. Effects of aerosolized surfactant in patients with stable chronic
bronchitis. .A prospective randomized controlled trial. JAMA 1997:
278tl7):1426-l43l.

20. Tamaoki J. Chiyotani A. Kobayashi K. Sakai N. Kanemura T.
Takizawa T. Effect of indomethacin on bronchorrhea in patients w ith
chronic bronchitis, diffuse panbronchiolitis. or bronchiectasis. Am
Rev Respir Dis 1992:145(3):548-552.

2 1 . Tamaoki J. Chiyotani A. Tag.iya E. Sakai N. Konno K. Ellcct of long
term treatment with oxitropium bromide on air« ay secretion in chronic
bronchitis and diffuse panbronchiolitis. Thorax l994;49(6»:545-.548.

22. Jaffe A, Bush A. Anti-infiammatory effects of macrolides in lung
disease. Pediatr Pulmonology 2001:31(6):464-473.

23. ^ulic O. Erakovic V, Parnham MJ. Anti-inflammatory effects of
macrolide antibiotics. Fur J Pharmacol 2001:4291 1-3):209-229.

822

Respirator') Care • Jli.y 2002 Vol 47 No 7

Airway Clearance Strategies for the Pediatric Patient

Kathryn L Davidson RRT

Introduction

Adherence

Chest Physiotherapy

Breathing (lames

Diaphragmatic Breathing and Huffing

Active Cycle of Breathing Technique

Positive Expiratory Pressure Therapy

High-Frequency Chest Wall Oscillation

Oscillating Positive Expiratory Pressure

Autogenic Drainage

Summarv

Clinicians who care for cystic fibrosis (CF) patients have many techniques to choose from to
facilitate mucus clearance. Little has been published about when to introduce the various tech-
niques and in what order to teach them. Debates have occurred over these issues in the CF
community, and there is now consensus on some topics. It is very important to teach adherence to
therapy at an early age. Adherence to an airway clearing regimen assists in maintaining good
pulmonary function in CF patients. Knowing when and how to introduce airway clearance tech-
niques beyond chest physiotherapy (CPT) is clinically relevant and useful. A 5-position modified
CPT routine can be used with infants and children, and it takes less time and may improve
adherence. Infants and toddlers can be taught breathing games that eventually lead them to per-
form diaphragmatic breathing and huffing. Once they have mastered diaphragmatic breathing and
huffing, children can be taught the active cycle of breathing technique. Modified CPT can be
phased out at that point. Positive expiratory pressure therapy can usually be introduced around
6-7 years of age. High-frequency chest wall oscillation, oscillating positive expiratory pressure,
and autogenic drainage all follow. CF patients should be given every opportunity to learn and
master various techniques to promote mucus clearance. Key words: cystic fibrosis, CF, airway
clearance, adherence, chest physiotherapy, breathing games, diaphragmatic breathing, huffing, ac-
tive cxcle of breathing technique, positive expiratory pressure therapy, autogenic drainage, pediat-
ric. [Respir Care 2002:47(7):823-828]

Introduction last 10 years in the United States. There is an abundance

of literature about the various techniques: some is good

Airway clearance techniques for pediatric and adult pa- science: some not so good. But all of it boils down to

tients have improved and changed dramatically over the enhancing the ability to clear secretions from the airways

of sick lungs. The respiratory therapist is responsible for
introducing patients Id the various techniques at the ap-

Kathryn L Dasidson RRT is affiliated with the Respirator)' Care Depart-
ment. Primary Children's Medical Center. Salt Lake City. Utah.

Ms Davidson presented a version of this repon at the 17th Annual New Correspondence: Kathryn L Davidson RRT. Respiratory Care Depart-

Horizons Symposium at the 47lh International Respiratory Congress. San ment. Primary Children's Medical Center. 100 N Medical Drive. Sail

Antonio. Texas. December 14. 2001. Lake City UT 841 \i. E-mail: pckdavid@ihc.com.

Respiratory Care • July 2002 Vol 47 No 7 823

Airway Ci.farancf. Strategies for thf: P[-;diatric Patient

propriate ages. Not nuich has been published wilh regard
ti) when to start the various iechiiic|Lies. which leehniques
are clinically uselnl at what age. and in what order we
should teach them. 'I'his review addresses llu)se questions
with regard to pediatric cystic fibrosis (CF) patients. My
purpose here is not to discuss the pros and cons of the
science behind the technic|ues or how to do the techniques,
but. rather, when, how, and why to incorporate them into
the life of a young CF patient. Many of the airway clear-
ance techniques can be used with other patient populations
as well, but the focus here is to provide information clin-
ically relevant and useful to CF patients.

Adherence

The key to CF care is patient adherence to therapy, and
it is important to instill adherence at a very young age. CF
patients should grow up with the feeling that doing their
therapy is as important as brushing their teeth or going to
school — facts of life and behaviors that are not optional.

Remember that CF is the patient's disease, not the par-
ents" disease. The family is very important, but the em-
phasis should always be on teaching the child to care for
him or her self. Traditional chest physiotherapy (CPT) is
not very conducive to that recognition, because it requires
a caregiver (usually a parent) and a young child cannot do
CPT alone.' But there are several quite effective tech-
niques that a child can learn to do alone.

The ability to perform therapy independently — without
equipment or the presence of a caregiver — is very impor-
tant. These children are only "patients" when they are in
the hospital or clinic: the rest of the time they are just kids,
with plans, activities, and lives to lead. Most kids like to
have sleepovers with friends: how difficult it must be to
try to plan a sleepover and still leave time for mom or dad
to do your CPT. How much nicer it would be to be able to
go to your friend's house and be able to independently
take 20 min out of the evening to do your active cycle of
breathing technique (ACBT) and then go back to playing
with your friend. The child would thus accomplish 2 dis-
tinct things: doing the therapy and living a normal, inde-
pendent life!

All therapies that can be taught to adults can be taught
to children — and should be. Some techniques must be ad-
justed; others should probably wail until the child reaches
a certain age. The point is to introduce various airway
clearance techniques so the patient has several to choose
from. You want the patient to be at least familiar with all
the techniques. As the patient becomes proficient in the
various techniques, one technic|ue may prove more effec-
tive. It is equally important to teach children and their
parents that one technic|ue may work better than another at
certain times, because the dynamics within the CF lung
change over time — sometimes quite rajiidly in the pres-

ence of infection. The motto should be "If I'm not moving
mucus, 1 should try a different technique." No one tech-
nique is perfect for every lung condition. It takes time to
master the various techniques, hut knowledge is a power-
ful tool in CF.

Chest Phy.siothcrapy

Percussion and postural drainage is the traditional form
of airway clearance for CF.- It is the first airway clearance
technique taught to parents, from infancy on up. Outside
the United States, other techniques are used with newborns
through 4-year-olds. Mask positive expiratory pressure
(PEP) is used from infancy to adulthood in some European
countries. Bubble PEP is used for toddlers. In Belgium a
modified version of autogenic drainage (AD) is used with
infants. We do not use these techniques often in the United
States with the infant population, and a detailed discussion
of the merits and demerits of these therapies with babies is
beyond the scope of this review.

At my institution we use a 5-position modified CPT
routine (Table I ). Always remember that CPT requires an
additional caregiver. Many of our patients' parents have
other children to care for. careers, and hobbies — they have
a life outside of CF.' And parents usually do not modify
therapy on their own: they either do it as they were in-
structed or they don't do it at all. Our goal should be to
make therapy something they can accomplish in a reason-
able period of time. A 12-position. full CPT treatment
takes a minimum of 45 min to an hour. It is important to
reduce that time so that parents can reasonably accomplish
some therapy. In real life it is quite difficult for a parent to
conduct an hour of therapy in the morning while they are
trying to deal with all the other parts of hectic early morn-

Table I. Five-Position Modified Chest Physiotherapy

Two Uprighl Posilians

1 . Anterior apices on both sides of the sternum

2. Posterior apices ori both sides of the spine
Percuss the upper third of the chest only.

The front can be done with the patient leaning sliyhth backward.
The back can be done with the patient leaning slightly forward.
Thrci' Treiulelenhiirg Posilions*

3. With the patient lying on his or her left side, percuss the right
side from the armpit to the bottom of the rib cage. mo\'ing over
the anterior middle chest if possible.

4. Wilh the palieni lying on his or her stomach, percuss the bottom
two thirds of the back on both sides of the spine.

5. With the palieni lying on his or her right side, percuss the left
side from the armpit to the bottom of the rib cage. mo\ ing over
the anterior middle chest if possible.

•Trendelenburg poMlion is onl\ tor pjliciils over 2 yean. old. Use a nal-lying position if the
patient is under 2 years old or a slightly upright position \i the patient has reflux.

824

Rh-spirator^' Carf • JiiLV 2002 Vol 47 No 7

Airway Clharanci; STRATHciins ior the Pediatric Paiii;ni'

ings. As many as 209c of our families have more tliaii I
child with CF. which increases the careiziver's tasks greatly.
They may have other children to get off to scIkhiI. a joh to
get readv for. and breakfasts land medications) to prepare.
Thus, the 5-pi)siiion modified CPT routine facilitates ad-
herence; we siri\e to make it a reasonable undertaking for
a busy parent.

It is also important to standardize care among the hos-
pital, home care company, outpatient clinic, and home.
Caregi\ers bect)me confused if each entity does the ther-
ap\ differently. We have taught all our Imme care com-
panies, hospital-based therapists, and clinic personnel the
same 5-position CPT regimen, and repetition of the same
therapy by each entity cements the process in the parents'
minds, so they ha\e little or no trouble remembering ex-
actly how to do the therapy.

In the .^-position modified CPT routine described in
Table 1. the lower areas of the chest are done in Tren-
delenburg positii)n. though Trendelenburg should be used
only w ith children o\ er age 2. CF patients have a very high
incidence of gastric retlux. and infants and toddlers put in
Trendelenburg position for CPT have a higher rate of com-
plications from their CF. including more hospitalizations,
more upper and lower respiratory tract infections, and wor.se
chest radiograph scores. With patients under age 2. CPT
should be done in a fiat position, not in Trendelenburg. For
patients with known gastric reflux. CPT can be done in a
slightly upright position, depending on the individual pa-
tient's circumstances.-'-''

Each of the 5 areas should receive 5 min of percussion.
This can change when a child reaches the magical "age of
manipulation." When kids reach 3-4 years of age they
have learned the art of manipulation: they have learned the
use and power of the word "Nol" Parents need to be in-
stnjcted through this phase not to skip any of the positions.
However, they can shorten the percussion time for each
position. Sometimes it ends up at I min per position, but
all positions are done. This way the child learns that, even
if they kick, scream, cry, or bite, his parents are still going
to do the therapy. It is the young patient's first lesson in
the importance of airway clearance and adherence: therapy
is so important that even if he does tenible things his
parents still do it! We teach diversion techniques such as
watching a special video or reading a special book as a
reward for being good during therapy.

Breathing Gaines

At about 9 months, babies become very good at imitat-
ing their family members. This age child can be taught to
cough on command. In the same way parents teach the
child to wave bye-bye. they can teach him to cough. This
generally involves lots of clapping, cheering, and laughter.
The hospital-based therapist teaches the parents to teach

their child. The baby imitating a cough is the first real
"breathing game." and once ihe child has accomplished
this, it should be incorporated into his CPT. In between
CPT jiositions, the infant is eneiiuraged to play breathing
games.

Breathing games are the beginnings of advanced airway
clearance for toddlers. The purpose is to have a fun way to
begin deep breathing and controlled exhalation with young
patients whii would not otherwise accomplish these tasks.
There are many types of breathing games (Table 2). in-
cluding toy wind instruments.

Start with the easiest games and incorporate them into
the CPT. Percuss the appropriate segment for 3-3 min.
then stop and have the child blow on a pin wheel for a few
minutes, then continue on to the next CPT percussion
segment. As a child matures and becomes able, move the
object farther away, which requires progressively larger
breaths to blow the object.

Keep in mind the attention span of very young children.
Alternating games throughout the treatment may be help-
ful, though some children want only to blow that brightly
colored feather off your hand — nothing else will do! Go
with the child's wants and needs. A "CPT toy box" should
be recommended to all parents. This special box contains
all the makings of fun breathing games, including those
coveted musical wind instruments. The toy box comes out
only during treatment times; this keeps it special in the
child's view. (As well, many parents are more than happy
to keep the musical instruments packed away except dur-
ing treatment times!)

Diaphragmatic Breathing and Huffing

The long-term purpose of these games is to teach dia-
phragmatic breathing and huffing, which are the basis for
all the advanced airway clearance techniques. As the child
gets older you can start to use the time in between CPT
segments to teach "belly breathing." Younger children can
be taught diaphragmatic breathing by using a small stuffed
animal set on the abdomen: as the air goes in, the bear goes
up; as the air goes out, the bear goes down. Older children
who have difficulty synchronizing the diaphragm will ben-
efit from a heavier object, such as a book, on the abdomen

Table :

Breathing Games

• Blowing bubbles

• Bliiwing on pinw heels

• Blowing anion balls or pom-poms or (ealhers oil an open palm

• Paper sailboat races across the balhiub

• Race cotton balls across the table using "air power"

• Blowing out candles; progressively move the candle larther away

• Musical wind instruments played with gusto

Respiratory Cari-; • July 2002 Vol, 47 No 7

825

Airway Clearance Strategies for the Pediatric Patient

while learning or perfecting the skill of diaphragmatic
breathing. Teaching this is best accomplished with the
child supine with the knees up.

Start to incorporate huffing into the teaching around
3-4 years of age. The child needs to know diaphragmatic
breathing before you introduce huffing. This is taking
breathing games to the next level. Modified versions of the
same games can be used to accomplish low and high huffs.
Modify the game of "'blowing a cotton ball off an open
palm" by having the child hold a cardboard mouthpiece in
between the teeth and "huff the cotton ball off the palm.
This changes the mechanism from blowing (as through
pursed lips) to huffing, which is through an open glottis
and emanates from the chest and airways, not the throat.

Making the leap from randomly huffing a cotton ball to
doing high and low huffs is not too difficult at this point.
Low huffs use a tidal volume or slightly larger than tidal
volume breath, a breath-hold of several seconds, then a
slow, controlled exhalation; this is the "slow and easy"
huff. The high huff requires a vital capacity breath, breath-
hold, then a strong, short exhalation: this is the "strong and
fast" huff. It can be helpful to teach the child to "wiggle"
the cotton ball with the low huff and to "blow it off" with
the high huff. You can also use a facial tissue held up in
front of the mouthpiece to demonstrate the difference be-
tween how the tissue flutters with a low huff versus a high
huff. Disposable cardboard mouthpieces are readily avail-
able and work well with small children, but you will need
a supply of these as they are not durable. Any large-orifice
short tube can be used (eg, a T-piece connector from a
nebulizer or a nondisposable pulmonary function test
mouthpiece).

There are many huffing games that can be used to teach
the art of high and low huffing. A mirror is a valuable aid
to this endeavor. Little children can play a ""3 little pigs'"
game and "huff and puff into the mirror. Older children
can be taught just by having them fog up the mirror ap-
propriately.

Active Cycle of Breathing Technique

Once a child has learned diaphragmatic breathing and
huff, he or she is ready to move on. From about 4 years of
age most are ready for several different airway clearance
techniques (Table 3), including ACBT, which is a combi-
nation of diaphragmatic deep breathing, breath holds, and
huffing (Fig. 1).^ At this point, decrease the amount of
percussion time and increase the time devoted to teaching
ACBT, eventually switching completely to just ACBT for
20 min. My institution recommends 20 min of airway
clearance per session, which can be by any method and
can be combined with medication delivery, such as albu-
terol or dornase alfa. Use of a kitchen timer is encouraged.
The switch to ACBT generally occurs around 4-5 years of

Table 3. Airway Clearance Techniques by Age

Infants Chest physiotherapy

Toddlers Chest physiotherapy and breathing games

2—4 year olds Chest physiotherapy, breathing games, belly

breathing, and hulTing
^ 4 years old Chest physiotherapy, active cycle of breathing

technique, and beyond

age, but the decision of when to switch depends on the
family dynamics and the individual child.

ACBT does not need to be combined with any other
therapy. While ACBT is being taught, parents and care-

Fig. 1. Active cycle of breathing technique.

826

Respiratory Care • July 2002 Vol 47 No 7

AiRw \v Clearance Strategihs ior thh Phdiatrr- Path ni

givers may question the adequacy of the therapy and may
v\ant to supplement early ACBT with modified CPT. Chil-
dren should he taught ACBT and should practice il lor
several months before moving on to another form of ther-
apy. Younger children generally need quite a bit of coach-
ing: but as the\ learn the routine, the coaching sessions can
be reduced. It is important during hospitalizations to re-
view the therapies the patient already knows: Can they do
ACBT on their own without coaching' Are they using
good positioning? Are their huffs producli\e? Are they
doing it for 20 minutes?

Positive Expiratory Pressure Therapy

Once the child is able to pertbrm diaphragmatic breath-
ing, huffing, and ACBT with appropriate breath holding
(this is usually around 6-7 years of age), move on to PEP
therapy.'^" My institution uses the TheraPEP de\ ice (DHD
Healthcare. Wampsville, New York), in part because it has
a built in manometer sNstem that we believe is imperative
for teaching young children to do PEP therapy correctly.
Some aerosol treatments are given in-line with the Thera-
PEP. so therapy time is brief (20 min). The TheraPEP
produces a positive expiratory pressure of 10-20 cm H^O.
It has several sizes of fixed-orifice resistor hole by which
to \ar\' the pressure and flow to achieve the proper PEP.
making the device useful for a wide range of pulmonary
function levels. The inspiratory side is unobstructed. The
device does not require any pressurized gas or other power
source (other than a pair of lungs).

Patients are taught to do 15 PEP breaths in a nnv. with
good posture and breathing technique, after which they
stop and do a cycle of ACBT or (if they know it) AD.
Once a patient has learned AD. he or she can choose either
ACBT or AD for use in between sets of PEP. The cycles
of PEP and ACBT are repeated for 20 min.

High-Frequency Chest Wall Oscillation

High-frequency chest wall oscillation (HFCWO) is an
alternati\e therapy. The Vest (Advanced Respiratory. St
Paul. Minnesota) is a device that consists of an intlalable
vest connected by hoses to an air pulse generator that
rapidly inflates and deflates the vest, gently compressing
and releasing the chest wall to create high-frequency os-
cillatory air flow within the lungs, which results in cough-
like shear forces and alters the ph) sical properties of the
mucus, thus increasing mucus mobilization.'" '- HFCWO
therapy generally takes about 30 min: 20 min of oscillation
time and additional time for huffing or coughing.

HFCWO can be very useful in households that ha\e
more than one child with CF. The Vest can also be helpful
with patients who have problems with adherence. Because
The Vest requires little or no patient concentration, the

patient can do other things, such as play video games,
explore the Internet, or watch television. However, pa-
tients with serious adherence problem may not fare any
better with The Vest. In any event, all patients should
know several therapies and use them, as no one form of
airway clearance is going to be the right one all the time.

One advantage of The Vest is that it has a built-in meter
that monitors the hours the system has been in use, which
allows the clinician to determine adherence and thus make
appropriate decisions regarding the efficacy of keeping the
machine in that patient's home.

There are a few down sides to The Vest. It is not very
portable; it is rather noisy, quite expensive, and does not
dispense with the need for huffing.

The Vest can be used with a patient who has a gastros-
tomy tube or an indwelling tunnelled intravenous access
catheter. To do so, foam can be cut to size to surround the
area of the gastrostomy tube or catheter, or the vest buck-
les around that area can he left undone.

Oscillating Positive Expiratory Pressure

At my institution, oscillating PEP is used only as an
adjunct therapy. ' ' Many centers use it as a primary form of
airway clearance. The patient can use it for 5 of the 20
minutes of the treatment time or use it after the regular
therapy if he or she chooses. The oscillating PEP valve is
very patient-dependent. We have found it difficult to eval-
uate the adequacy of this therapy and also that it is difficult
for children to master effectively. If it is chosen for use
with a pediatric patient, it is imperative that the patient is
thoroughly and carefully trained and that the patient's tech-
nique be evaluated over lime.

Autogenic Drainage

At my institution, we begin to teach AD^ '"'"' when the
patient is around 1 2 years of age. We have found that the
patient needs to have a fair amount of concentration to
master the technique, but, once mastered, it is very effec-
tive. In Belgium, where the technique was developed, a
version of AD is used from infancy on. This is a very
intriguing concept, but we have not had much success in
getting our younger patients to master it.

When AD is taught, the environment must be conducive
to learning. A quiet room w ith no distractions is necessary.
Because teaching AD is a very "hands-on" experience, it
is wise to set up the room appropriately. The best way we
have found is to have 2 straight-back chairs placed in a
row. The therapist sits behind the patient, where he or she
can coach the patient through the breathing. It is best to
have one hand placed on the lower rib cage/upper abdo-
men to feel diaphragm movement. The other hand is free
to be placed wheie needed. For example, if the patient has

Respiratory Care • July 2002 Vol 47 No 7

827

Airway Clearance Strategies for the Pediatric Patient

a tendency to use his or her shoulders when taking deep
breaths instead ofusinji the diaphragm, the therapist should
place the left hand on the diaphragm and the right hand on
the patient's right shoulder, pressing down slightly to en-
courage use of the diaphragm and remind the patient not to
use the shoulders. The right hand can also feel the back to
locate areas of secretions, and then the patient can use
directed breathing to try to get more air to that area. The
therapist should be leaning in close to the patient while
coaching so he or she can hear the exhalations and crack-
les that indicate the right time to move on to the next level.
Patients and families need to be aware of the closeness
of the coach during instruction. When appropriate, a chap-
crone should be present. Patients (especially young ones)
usually need several good coaching sessions before they
can do AD on their own. Many teenagers like to do AD to
music. I recommend to them to create a 20-min tape of
their favorite soothing music to play while doing their AD:
when the tape is done, so is the AD session.

Summary

Alternative airway clearance techniques such as AD,
ACBT. PEP, and oscillating PEP are now being used more
frequently in the CF and non-CF patient populations. These
therapies can be tried with patients who suffer mucus re-
tention that is not responsive to spontaneous or directed
coughing (eg, an asthma patient who cannot clear sputum
with coughing). The practitioner must be very careful when
using PEP (and some of the other therapies) to assure that
the therapy is not causing further airway collapse. Wheez-
ing indicates dynamic collapse, and the air flow must be
slowed for the therapy to be effective. Patients need to be
well trained in this modality to benefit from its mucus-
clearing effect.

CF patients and their families should be knowledgeable
about all methods of airway clearance. Start with modified
traditional CPT and add in therapies as the patient grows
older. It is very important to teach the families as well,
because most of the patient's early education about airway
clearance is going to happen at home. The therapist should
strive to teach the patient independence in airway clear-
ance and to teach many different methods of airway clear-
ance. The goal is always to improve mucus clearance, and
if that goal isn't being met, the patient should have several
forms of therapy to try. Remember: it may take a variety
of therapies to move mucus!

ACKNOWLEDGMENTS

I sincerely thank Barbara Chalt'ield MD for her contrihuticm to the prep-
aration ol this review.

REFERENCES

1 . Passero MA. Remor B. Salomon J. Patient-reported compliance with
cystic fibrosis therapy. Clin Pedialr (Phila) I98I;2()(4):264-268.

2. Matthews LW, Doershuk CF, Wise M, et al. A therapeutic regimen
for patients with cystic fibrosis. J Pedialr I964;65:.S.'>8-575.

3. Davies LK. Comparison of dependent-care activities for well sib-
lings of children with cystic fibrosis and well siblings in families
without children with chronic illness. Issues Compr Pediatr Nurs
mW;l(i(2):91-98.

4. Button BM, Heine RG. Calto-Smith AG. el al. Postural drainage in
infants: to lip or not to tip. that is the question (abstract). Pediatr
Pulmonol SuppI 1995;12:108-109.

5. Button BM. Heine RG. Catto-Smith AG. Phelan PD. Postural drain-
age in cystic fibrosis: is there a link with gastro-oesophageal retlu.x'.'
J Paediatr Child Health 1 998:34(4): 330-334.

6. Button BM, Heine RG. Catto-Smith AG, Phelan PD, Olinsky A.
Postural drainage and gastro-esophageal retlux in infants with cystic
fibrosis. Arch Dis Child 1997:76(2): 148-150.

7. Miller S. Hall DO. Clayton CB. Nelson R. Chest physiotherapy in
cystic fibrosis: a comparative study of autogenic drainage and the
active cycle of breathing techniques with postural drainage. Thorax
1995:50(2): 165-169.

8. Falk M, KeLstrup M, Andersen JB, Kinoshita T, Falk P. Stovring S.
Gothgen I. Improving the ketchup bottle method with positive ex-
piratory pressure, PEP. in cystic fibrosis. Eur J Respir Dis 1984;
65(6):423-432.

9. Hofmeyr JL. Webber BA, Hodson ME. Evaluation of positive ex-
piratory pressure as an adjunct to chest physiotherapy in the treat-
ment of cystic fibrosis. Thorax 1986:4l(l2):95l-954.

10. Hansen LG, Warwick WJ, Hansen KL, Mucus transport mechanisms
in relation to the effect of high frequency chest compression (HFCC)
on mucus clearance. Pediatr Pulmonol I994;I7(2):I I3-1 18.

11. King M. Zidulka A. Phillips DM, Wight D, Goss D. Chang HK.
Tracheal mucus clearance in high-frequency oscillation: effect of
peak fiow rate bias. Eur Respir J I990;3( 1 ):6-l3.

12. Majaesic CM, Montgomery M, Jones R, et al. Reduction in sputum
viscosity using high frequency chest compression compared to con-
ventional chest physiotherapy (abstract). Pediatr Pulmonol SuppI
I996;I3:A358.

13. McIIwaine PM, Wong LT. Peacock D, Davidson AG. Long-term
comparative trial of positive expiratory pressure versus oscillating
positive expiratory pressure (flutter) physiotherapy in the treatment
of cystic fibrosis. J Pediatr 200l:l3S(6):S45-850.

14. Schoni MH. Autogenic drainage: a modern .ipproach to physiother-
apy in cystic fibrosis. J R Soc Med l989;Suppl 16:32-37.

15. Davidson AGF, McIIwaine PM, Wong LTK, et al. A comparative
trial of positive expiratory pressure, autogenic drainage and conven-
tional percussion and drainage techniques (abstract), Pediatr Pulmo-
nol SuppI I988;2:I36A.

16. Lindemann H. Boldl A, Kieselmann R. Autogenic drainage: efficacy
of a simplified method. Acta Univ Carol [Med| (Praha) I990;36(I-
4);2I0-2I2.

828

Ri;spiR.ATORY Care • July 2002 Vol 47 No 7

Ki'vk'Ks of Itciiiks and Otlior Media. Nolo lu publishers: Sfiid review copies of books. Illins,
lapes. and software lo Rlshratory Cahe, 6IX) Ninlh Avenue. Suite 702. Sualtle WA 98104.

Books, Films,
Tapes, & Software

Physiotherapj in Re.spiratorv Care: .\n
K\idenc'i'- Based .Vpproach to Respiratory
and Cardiac Management, mJ cdicicm. Al-
exunilni Hoogti. t'hcltcnh;i[ii. L'nited King-
dom: NclsDii Thornes Ltd. 2001 . Soft co\er.
illustrated. 550 pages. S39.

This text pro\ ides iwideis witli an under-
standing ot how functioning and quahty of
life are impacted by cardiovascular/pulmo-
nary dysfunction or failure (ie. compromised
oxygen transport system). The book empha-
sizes the pulmonary system and acute, life-
threatening, chronic, and disabling diseases.

The book uses radiographs, drawings,
cartoons, diagrams, pictures of patients,
quotes from patients and recognized author-
ities, and relevant references to the scien-
tific literature. It provides opportunities for
cerebral exercise with its case studies and
interpretative analysis/response at the end
of each of the 17 chapters. In addition, a
brief literature appraisal is offered, chapter
by chapter, to prompt personal reflection
and critique. For example, page 1 18 quotes
the fin7/.v// ,/()(//■/;((/ o/Micv;/)!;: "Bars of soap,
if used, should be kept dry," with the re-
sponse added, "That's a good idea." in ref-
erence to avoiding a potential culture me-
dium for bacteria growth.

Compared to its first edition ( 1991 ) and
second edition ( 1996). this third edition has
more of everything: pages (243. 365. and
550. respectively), radiographs, content re-
source infonnation (Appendixes A through
F), clinical applications, cartoons, tables,
graphs, and craftily highlighted (sky-blue)
text material.

In all 3 editions the author has targeted
her readership to be physiotherapy students
and clinicians and nurse specialists in respi-
ratory and intensive care. As a physical ther-
apist educator and clinical specialist I did
not find the content lo be descnptive of the
way a physical therapist would conduct clin-
ical practice in the United States. The book
focused primarily on one (cardiovascular/
pulmonary) of the 4 (neuromuscular, mus-
culoskeletal, integumentary) "Preferred
Practice Patterns" published in the Guide lo
Physical Therapist Practice. This text ap-
plies intervention strategies of postural
drainage therapy, as operationally defined
in the American Association for Respira-

tory Care's Clinical Practice Guidelines.
Thus, the book emphasizes care for persons
with pulmonary /cardiovascular compromise
to be more clinically generic among disci-
plines, not exclusive to the physiotherapist
or nurse specialist in respiratory care alone.
Enhancing oxygen transport is basic to car-
ing for eveiy patient.

I found this third edition to be well or-
ganized and reader-friendly. Similar to the
previous editions, the writing style uses Brit-
ish spellings, such as "colour," "oedema,"
"aetiology," "laboured," and "anaemic."
Once the reader acclimates to that style, it
ceases to be distracting. However, the text
is peppered throughout with references to
and familiarity with British culture. For ex-
ample, most of Appendix C (Resources) per-
tains only to the United Kingdom, and some
British colloquialisms go unexplained (eg,
"take the odd potter to the toilet" (page 73).
But these are shoilcomings that can easily
be overlooked.

The author and publisher promote this
book as being evidenced-based, whereas ear-
lier editions were labeled as espousing a
problem-solving approach. Frankly, I found
this edition no more evidenced-based than
the previous editions, though the cited lit-
erature was updated and appropriate. Nev-
ertheless, no meta-analyses were included.
On the other hand. I thought this edition
used more of a problem-solving approach
than either of the previous editions. The case
studies given in each chapter are new to this
edition.

The author's use of subtle humor was
usually amusing and refreshing: listen "op-
timistically for bowel sounds over the kid-
ney" (page 41); "blow the living daylights
out of the machine" (page 58); "tattooed
archbishop" (page 167); "Man should no
more breathe through his mouth than take
food through his nose" (page 302). How-
ever, certain of the attempts at humor were
crude and offensive, such as the cartoon on
page 362. in which a female physiotherapist
is doing calisthenics while lying on her male
patient's chest in a hospital bed.

The author and publisher might not be
aware of the gender bias that was portrayed
in this 3rd edition. With rare exception, ev-
ery patient depicted in the drawings. c;u--
toons, and photos was male, whereas the

therapists/clinicians were typically female.
I do not believe that the author or publisher
intended to suggest that respiratory care is
more likely to be necessary for men nor that
physiotherapists and nurses are exclusively
female.

This text was relatively free of typograph-
ical errors, although an occasional editing
opportunity was missed (eg. "excercise" on
page 44). I found most illustrations and fig-
ures to be helpful and well done. The chest
radiographs were particulan' crisp, clear, and
instructional. However, one illustration used
in all 3 editions (Fig. 10.6 on page 9 of the
current edition) was confusing. It used the
tertii "horizontal position" rather than "side-
lying" or "supine" to explain the concept in
question.

I believe the concluding chapter (Chap-
ter 17, "Evaluation of Respiratory Physio-
therapy") would have best served this text
as the introductory chapter instead. Readers
would have had "evidenced-based" seeded
in their thought process, up front.

Clinical application based on anatomic
and physiologic principles is a definite
strength of this text. Examples include: signs
and symptoms of dehydration approached
in differential fashion (page 40); stratifica-
tion of asthma (page 76); the effect of po-
sitioning with one-sided pathology (page
152); use of a fan to reduce breathlessness
(page 174); and intracranial pressure mon-
itoring (page 402).

1 believe this book v\ould be a refreshing
and useful resource for students, educators,
and practicing clinicians alike, in nursing,
respiratory therapy, occupational therapy,
and physical therapy.

Dennis C Sobush MA PT CCS

Curative Care Network

Froedtert Memorial Lutheran Hospital

Department of Physical Therapy

College of Health Sciences

Marquette University

Milwaukee. Wisconsin

Mosby's Complementary & Alternative
Medicine: A Re.search-Based Approach.

Lyn W Freeinan PhD and G Frank Lawlis
PhD. St Louis: Mosby. 2001. Hai\l cover,
illustrated, 532 pages, S49.

Respiratory Care • July 2002 Vol 47 No 7

829

Books. Films. Tapes, & Soitware

This book's preface stales. "A central
problem with complementary and alterna-
tive medicine science in the United States
has not been its existence but its accessibil-
ity. Dr Freeman's book will help make this
knowledge available to academics and pro-
fessionals who choose to integrate this im-
portant literature into health care practice."

This book provides a \aluable first step
in what should prove to be a long line of
attempts to educate health care practitioners
and educators about what has come to be
known as complementary and alternative
medicine.

The preface claims that this text, "in its
entirety, provides a comprehensive review
of complementary medicine and alternative
therapies for health professionals at both the
undergraduate and graduate levels." Clearly
this book is designed for continuing educa-
tion of clinical practitioners and those within
the "business of medicine." The book's
stated intent is the "application of critical
thinking"; it is intended to clarify what we
know of complementary and alternative
medicine in relationship to our current sci-
entific understandings and what application
this might have in health care decisions.

The book is composed of 5 units that
encompass 1 8 chapters. A positive attribute
of the book is that the reader can start with
any of the 5 units and read it separately with-
out loss of integrity of the subject matter.
Mind-body integration is discussed in Unit
One, including the physiologic pathways of
communication, which include the hypotha-
lainic-pituilary-adrenal axis, through to a his-
tory and evolution of psychoneuroimmunol-
ogy. This section is the most direct and
understandable, because it appears to come
from the authors' expertise in this field.

Unit Two describes mind-body interven-
tions such as relaxation, meditation, biofeed-
back, hypnosis, imagery, and pain control
therapies. As the textbook progresses into
Unit Three, which describes the categories
of alternative medicine, the strength of the
organization begins to break down because
of an alleinpt to describe the philosophical
underpinnings of chiropractic, acupuncture,
homeopathy, and ma.s.sage therapy and their
proposed mechanisms of intervention. As a
practitioner of acupuncture and oriental
medicine 1 was pleased with the presenta-
tion of the basic subject matter but noticed
the lack of emphasis on the organizing par-
adigm of acupuncture and oriental medi-
cine. Its philosophical under|iinnings. mech-
anisms of action and intervention, and

methods of diagnosis are of a different model
and therefore access a healing and recosery
process in a different manner.

Complementary self-help strategies are
outlined in Unit 1-our. There is a detailed
section on the history, pharmacology, re-
search, and clinical application of herbs as a
medical intervention, but this section is de-
\()id of any discussion of traditional Chi-
nese herbal medicine, which has one of the
oldest pharmacopoeias as well as an alter-
native theory /practice model. In short, herbs
are treated in the same manner as synthe-
sized medicines: one herb for one symp-
tom, which is a limiting approach. Unit Four
also includes a section devoted to exercise
as an alternative therapy.

The final section. Unit Five, details en-
ergetics and spirituality.

The organization of the material, from
the chapter objectives to the critical think-
ing and clinical application exercises, was
useful only from the perspective of an un-
dergraduate student. Though the outline for
the subject matter provided a framework to
detail the information, and the exercises at
the end of each chapter stimulated learning
on a particular topic, if the intended out-
come is to provide a resource and informa-
tion ba.se for professionals or businesses,
these wrap-up sessions at the end are not
useful. Also, the inclusion of expert com-
mentaries (there is one "An Expert Speaks"
section in each unit) was a weakness of the
book. More useful would have been for the
expert to be the author of his or her disci-
pline's section, with information written
from his or her perspective regarding the
healing abilities or the healing potential of
that specialty.

By attempting to be too comprehensive
in much too broad a subject area, the book
is not able to be more than a guiding instru-
ment for educators and clinicians. For a book
to be complete with such an aggressive
agenda it would need to be 10 times this
book's size. The attempt to detail comple-
mentary alterative medicine as a whole was
admirable, but to take an entire discipline
such as acupuncture and oriental medicine
and attempt to summarize it along with sev-
eral other disciplines that have different the-
oretical backgrounds fails to show the rich-
ness of the healing modalities in any of the
disciplines described. Though it is a diffi-
cult task to combine all these disciplines
into a comprehensive book, the editors were
able to achieve their intended outcome of
making the reader use nonjudgmental. clear.

critical analysis of the disciplines described.
The section on acupuncture was convinc-
ing, and 1 found only one spelling error.
However. 1 lack the expertise to judge the
sections on the other disciplines. 1 would
say this book is a good first step in an on-
going and needed process.

Jim Blair CRT LAC

Seattle Acupuncture Associates

Center for Comprehensive Care

Seattle. Washington

Pharmacology in Respiratory Care. Stu-
art R Levine Phami D and Arthur J Mc-
Laughlin Jr MS CRT. New York: .McGraw
Hill 2001. Hardcover.illustrated.386pages.
$49.95.

This book is essentially an adaptation of
a text entitled Basic Pluimuiailoi;\: written
by Henry Hitner and Barbara Nagle, both
PhDs in phamiacology. The rationale is to
provide respiratory care students a text lim-
ited to the information essential for their
specialty. A few other chapters are included
to complete the essentials of a comprehen-
sive text, but this volume, largelv outlined,
can be covered in the time allotted for a
respiratory care curriculum.

The first chapter. "Introduction to Phar-
macology," defines tenns essential to drug
description, specific objecti\es of treatment,
and basic information on drug sources and
effects. A logical sequence of phannacol-
ogy chapters is then presented, together with
a review of the clinical applications essen-
tial to respiratory care.

Chapter 2. "Biological Factors Affecting
the Action of Drugs." describes the basic
principles of pharmacokinetics, defining the
temiinology and objecti\es for the follow-
ing chapters and describing drug forms and
routes of administration. The phamiacoki-
netic di\ isions of drug absorption, distribu-
tion, metabolism, and excretion are clearly
outlined, with added definitions of half-life,
blood drug le\els. bioavailability, and fac-
tors of indi\ idual variation. Other topics in-
clude pediatric drug considerations, drug in-
teractions, and the terminology associated
u iih chronic dnig use and abuse. Chapter 3,
"Math Resiew and Dosage Calculations."
is a continuation of general phannacology.
introducing terminology and systems of
measurement. Formulas for dosage calcula-
tions, including those for pediatric patients,
are given. Since drugs are often adminis-

830

Respiratory Care "July 2002 Vol 47 No 7

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tered intra\cnously, methiids tor measuring
infusion rates are iiutlined.

Chapter 4. "Preventing Medication Er-
rors," was written by the co-editor. Stuail
Levine. It focuses on dmg terminology, la-
behng of concentrations and other specifics,
and the abbre\ iations commonly employed
in drug orders. This emphasis on safe prac-
tice is of p;iramount importance to students.

Chapter 3 begins the description of au-
tonomic drug therapy. It describes the basic
anatomy of the parasympathetic and sym-
pathetic divisions, with infomiation selected
on facts of clinical importance. Comparison
of the di\ isions is principally concerned with
the maintenance of homeostasis.

Chapters 6, 7, and 8 describe drugs pri-
m;iril\ belonging to the sympathetic, para-
sympathetic, and autonomic ganglionic drug
categories, with emphasis mostly limited to
their therapeutic applications. Adverse and
to.xic effects are described, and the scope of
the drugs" clinical safety boundaries are
clearly stated.

Chapters 9 and 10 describe peripherally
acting drugs, skeletal muscle relaxants, and
local anesthetics. Although these com-
pounds ;ire most often ordered by physi-
cians, their administration is often continu-
ous over extended periods, and their adverse
effects must be recognized and reported by
respiratory therapists. Since muscle relax-
ants are often essential for controlled me-
chanical ventilation, their systemic effects
must be well defined and are presented here
in detail, together with their drug antago-
nists. There is also a brief description of
centrally acting skeletal muscle relaxant
drugs. Routes of administration for local an-
esthetics (topically or via injection) are out-
lined, together w ith their adverse effects and
their indications for clinical use.

Chapters 1 1 through 14 describe drugs
that act principally on the central nervous
system. The first of these chapters describes
brain function and the physiologic relations
of its anatomic divisions, with particular em-
phasis on their roles in respiratory regula-
tion. Spinal cord activities are also briefly
described.

Chapter 12 focuses on sedative-hypnotic
drugs and ethyl alcohol.

Chapter 1.^ describes general anesthetic
drugs. This chapter is of particular value in
dealing with postoperative patients. The ef-
fects of general anesthetics on respiration
;ire of primary importance, but also their
profound effects on other physiologic sys-
tems are brieflv reviewed. Both inhaled and

intravenous agents are described, as are
dnigs iidjunctive to general anesthesia.

Opioid aniilgesics and antitussives ;irc the
subjects of Chapter 14. S|Tecial considerations
in ivspiraliiiy carv are descrilvd. such as un-
dcnentilation ;ind orthostatic hypotension.

Chapters I .S and 1 6 discuss cardiac phys-
iology and pathology and c;irdiac glycosides
employed in the treatment of congestive
heart failure. Chapter 17 deals with com-
piHuuis ihal affect blood coagulation, and
Chapter IS discusses antiallergics and anti-
histaminics. Chapter 19 addresses broncho-
dilator drugs and the treatment of asthma.
Investigational therapies, such as those in-
volving monoclonal antibodies and anticy-
tokines, are also described.

Adrenal steroids, antibacterial agents, an-
tiseptics and disinfectants, and antiviral
drugs are the subjects of Chapters 20 through
24. With the exception of Chapter 23 (a
discussion of herbal remedies for respira-
tory diseases, which was contributed by
Ellen Feingold). all the chapters specifically
describing drugs are drawn from the work
by Hinter and Nagle.

Chapter 25 is a summary of drug use
during mechanical ventilation. Written by
Viday Nadkami and Stuart Levine, it is a
review adapted from the book Essentials of
Mechanical Venrilation by Dean Hess and
Robert Kacmarek. The final chapter (Chap-
ter 26), "New Treatments in Respiratory
Care Pharmacology." is by Barbara Nagle
and Stuart Levine. The chapter describes
surfactants, nitric oxide, and pentamidine
isethionate, and provides a brief description
of the use of inhaled insulin for diabetes
niellitus.

Two appendixes are included. The first,
by Roberto Palermo and Arthur McLaugh-
lin Jr, review regulatory issues in the prac-
tice of respiratory care, particularly those
affecting medical direction and licensure
acts. The second appendix is a one-page
compatibility chart for nebulized respiratory
medications.

In summary, this book takes a useful di-
dactic approach to pharmacology and ther-
apeutics applicable to respiratory care. Un-
derstanding the properties, uses, and dangers
of drugs is of obvious importance to the
indoctrination of students. Virtually all re-
spiratory aspects of clinical practice dealing
with drug administration are discussed. The
book is well indexed, and subjects of not
only therapeutic but also medicolegal im-

plications can be readily located and are
adei|ualely covered in the outlined text.

Ilunh S Mathcwson MD

Respiratory Caic l^ducalion
University of Kansas
Kansas City, Kansas

Carbon Monoxide Toxicity. David G Pen-
ney, editor. Boca Raton. Florida: CRC Press.
2000. Hard cover, illustrated. 560 pages,
$99.95.

This is the second book on carbon mon-
oxide (CO) poisoning edited by Dr David
Penney. The first was Carbon Monoxide
(Boca Raton, Florida: CRC Press; 1996),
which covered CO analysis; formation, up-
take, and elimination in humans; effects on
the heart and lungs; effects on development
in animals and humans; and how CO can
impair learning, meinory. neuropsycholog-
ical function, and behavior. The first book
also had a chapter dealing with delayed se-
quelae of and possible mechanisms of CO
poisoning, as well as treatment of CO poi-
soning.

This new book. Carbon Monoxide Tox-
icity, which complements the first book, was
released in 2000 by CRC Press. Most of the
chapter contributors are different from those
in the first text. There are chapters regard-
ing the history of CO toxicology, the dis-
tribution of CO in various tissues and blood,
and health-based standards for ambient CO
levels. There are also chapters reviewing
CO detectors, the effects of CO on exercise
capacity, and the interacting effects of CO
exposure with concomitant increased alti-
tude exposure. Carbon monoxide can be
associated with other toxic gases, and a chap-
ter addresses that issue. There is a provoc-
ative chapter regarding the possibility that
CO may be an unrecognized cause of neur-
asthenia. A series of chapters deal with the
management of CO poisoning in the United
States and other countries. The chapter about
treatment of CO poisoning in the United
States is written by the same author as the
similar chapter in the first text and updates
that chapter. There is a discussion of scan-
ning techniques to investigate brain damage
from CO, as well as one on the effects of
low-level CO exposure. Dr Penny contrib-
uted a chapter on long-term CO poisoning,
and there is a chapter regarding the Carbon
Monoxide Support Study. The final chap-
ters deal with neuropsychological evalu-
ation of CO-poisoned patients, CO poi-

Respiratory Care • July 2002 Vol 47 No 7

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Books. Films, Tapus, & Software

soiling in children, CO's production,
transport, and hazards in building tires,
and approaches to dealing with CO in the
living environment.

This text is 560 pages long and reviews
CO toxicity in detail, but one needs to
have both the 1996 book and this edition
to have a foundation for understanding
CO poisoning.

The intended readership is broad. Cer-
tainly, many health care providers would
have an interest in this text, but, as well,
patients suffering from CO-related sequelae,
toxicologists, and even historians might tlnd
this book infomiati\'e. Most of the book is
written in language that respiratoi-y thera-
pists, nurses, and physicians can understand.

As Dr Penny states in the preface, one of
the book's purposes was to discuss topics
not covered by the first book, and in that he
has been successful. The literature regard-
ing CO poisoning is lengthy and compli-
cated, but this text successfully organizes
the infomiation into a readable and well-
organized fomi, and each chapter is thor-
ough and well referenced. The material was
appropriately selected, and most of the data
and arguments posed are clear and logical.
Most of the conclusions posed by chapter
authors are convincing, with the possible
exception of the one regarding neurasthe-
nia's relationship to CO poisoning. The text
is relatively easy to read, although it is a
lengthy text and takes some time to read in
its entirety.

Regarding specific chapters, the first
chapter is somewhat disorganized, but the
information presented is difficult to find
elsewhere, so this chapter is infomiative.

Chapter 2. regarding CO in breath, blood,
and tissues, and the measurement, endoge-
nous source, and biochemical effects of CO
was interesting.

I found Chapter 3, regarding CO detec-
tors and alarms, particularly informative and
thought it well worth reading by anyone
interested in the subject.

Although Chapter 4. which deals with
the setting of health-based standards for am-
bient CO and their impact on atmospheric
levels, presents substantial detail, 1 did not
fnid this infomiation particularly helpful as
applied to understanding threshold levels for
what should be considered toxic ambient
CO exposures.

The chapter regarding CO on work and
exercise capacity in humans is informative
and very well referenced. The sentences are
somewhat difficult to follow, but the infor-

mation about how CO affects exercise was
fascinating.

The information about interactions be-
tween altitude exposure and concomitant
CO poisoning was of particular interest to
me. since I have treated patients who suf-
fered CO poisoning while residing at
higher altitude.

Chapter 7, which deals with interactions
among CO, hydrogen cyanide, low-oxygen
hypoxia, carbon dioxide, and inhaled iiri-
tant gases, was stimulated by smoke-inha-
lation victims. Many assumptions would
have to be made to infer from such toxic
exposures, which the author reviewed in de-
tail. I was unaware of this information be-
fore reading this text and found this chapter
helpful, although many of the assumptions
may not necessarily be true with any given
toxic inhalation. Nevertheless, the chapter
is well thought out.

The review of CO poisoning and its man-
agement in the United States underscores
how common CO poisoning is in this coun-
try and potentially how under-recognized it
is. This information is valuable and should
help raise awareness of CO exposure and
prevention, which is paramount.

The discussion about death by suicide
(around the world) involving CO was inter-
esting and sad. These suicide rates are linked
to press events about suicide, and are also
inversely related to improved emission stan-
dards in automobiles.

The chapter by Albert Donnay, regard-
ing CO as a recognized cause of neurasthe-
nia, is provocative, although I am not con-
vinced that neurasthenia is linked to CO
exposure. The neurasthenia hypothesis is in-
triguing and may be accurate, but it is dif-
ficult to prove conclusively. Donnay made
reference to hand-held breath analyzers that
can delect CO and might be a suitable screen-
ing method for CO poisoning, but those an-
alyzers have not been validated for that pur-
pose, and the value of hand-held breath
analvzers fordetemiining CO poisoning re-
mains to be detemiined.

For this book Suzanne R While contrib-
uted a comprehensive update (to her chap-
ter in the first text. Carhdii Moncxidc) on
clinical treatment of CO poisoning. In the
next few years, new infomiation might mod-
ify current treatment recommendations, par-
ticularly regarding the role of hyperbaric
oxygen therapy for CO poisoning.

Discussion about CO poisoning in other
countries (including France, Poland, the
United Kingdom, and major cities in China)

encompasses the next several chapters. This
information reminds us once again how
common CO poisoning is and how it can
adversely affect health. IS Saing Choi, who
is well recognized in the field of neuroim-
aging and CO poisoning, offers a chapter
on this subject and ihe role of magnetic res-
onance imaging and single-photon emission
computed tomography. Dr Choi makes an
important point — that the prognosis of CO
poisoning depends on cerebral while matter
changes rather than those of the globus pal-
lidus — that challenges some physicians'
point of view. I agree with Dr Choi that
brain MRI and spectroscopy are more sen-
sitive than CT in detecting and evaluating
brain damage due to CO poisoning.

The chapters by Robert D Morris (low-
level CO and human health) and Dr Penny
(chronic CO poisoning! complement the
chapter by Alistair WM Hay. Susan Jaffer.
and Debbie Da\ is, "Chronic Ciu'bon Mon-
oxide Exposure: The Carbon Monoxide
Support Study." Studies of low-level CO
exposure indicate thai ambient CO levels
may have an important adverse effect on
persons with underlying heart disease. It is
possible that sensitive subpopulations who
are concurrentl\' exposed to other stress fac-
tors, such as cold, may be affected by CO at
concentrations previously thought to be safe.
However, the exact CO levels that can cause
disability in individual exposures remain un-
clear. Dr Penny offers a working definition
for chronic CO poisoning, which is "an ex-
posure to CO that occurs more than once
and lasts longer than 24 hours." He also
discusses the commonality of misdiagnosis
of chronic CO poisoning. The information
presented suggests that chronic CO poi-
soning could cause substantial morbidity.
These points are somewhat substantiated
by information presented by the chronic
CO exposure stiid\. in which question-
naires were distributed lo patients follow-
ing CO exposures.

Since CO is common and is associated
with pemianent physical, cognitive, emo-
tional, and psychological sequelae, the chap-
ter regarding neuropsy chological evaluation
of the CO-poisoned palieni is timely and
helpful. This chapter re\iews neuropsycho-
logical testing and the role of these tests in
patients with CO-related sequelae. The chap-
ter also includes sections regarding psycho-
therapy, psychiatric interventions, and neu-
rocognitive rehabilitation, which can be
potentially valuable for many patients suf-
fering CO sequelae.

832

Respika roRY Care • July 2002 Vol 47 No 7

Books. Films. Tapes, & Soitw arh

It is hclpliil that Dr White provided a
chapter regarding pediatric CO poisoning.
As expected, this chapter is thoroughly ref-
erenced.

There is a chapter that deals with CO
transport and How patterns of gases u ithin
burning buildings. The final chapter dis-
cusses how CO exposure can be dealt u ith
in the living environment. There are niulti-
ple possible sources of CO exposure all
around us. and this chapter deals with those
sources and how CO exposure can be min-
imized. The section regarding investigative
techniques for identifying CO sources is also
infonnative. especially considering that CO
exposure is common and may be under-
recognized and misdiagnosed.

Overall, the general appearance of the
book is satisfactory. The incidence of typo-
graphical errors is low. The clarity of the
illustrations is appropriate. The index is thor-
ough, and 1 found it relatisely easy to use.
The accuracy, timeliness, and coverage of
the references, by all of the authors, are very
good.

It is my opinion that this text comple-
ments the previous text, Carbon Monoxide.
nicely. Sections within this text should be
re\iewed by physicians who see patients
with CO poisoning or its sequelae. This text
should also be available to emergency de-
partments, respiratory therapists and nurses,
and neuroscientists \\ho may be seeing pa-
tients with CO poisoning. Patients who have
had CO poisoning and its associated se-
quelae may also find chapters within this
book helpful.

Lindell K Weaver MD

Hyperbaric Medicine

Shock Trauma Respiratory

Intensive Care Unit

LDS Hospital

Pulmonary Division

Department of Internal Medicine

University of Utah School of Medicine

Salt Lake City, Utah

Respiratory Care Sciences: \n Integrated
.\pproach. .^rd edition. William V Wojcie-
chouski. .-Xlbany, New York: Delmar Pub-
lishers. 2000. Soft cover, illustrated. 656
pages. S49.95.

In 7 chapters this book presents smdents
with much of the basic science required to
understand selected portions of algebra,
chemistry, mathematics, microbiology,
physics, physiologic chemistry, and statis-

tics. As stated in the preface, one goal of the
text is to "proxide respiratory therapy stu-
dents with basic science topics skewed to-
ward respiratory care and cardiorespiraton
anatomy and physiology." To a great extent
the book fulfills that goal.

The content is most suitable for respira-
tory care programs that have an integrated
science course. In that circumstance any or
all of the content might be used. Schools
thai reiiuire indis idual basic science courses
taught by different departments will find this
book less useful. For students who need to
releam specific mathematical operations, re-
view in preparation for examinations, or find
clarification on certain basic science sub-
jects, this book could be quite useful, though
the utility of this book will to some extent
depend on what other books are available,
since general respiratory care texts present
many of the same concepts.

Organizational components of the book's
design include: a list of formulas on the
inside Iront cover and the next 2 pages; the
periodic table of elements on the inside back
cover; a page of metric units, rules govern-
ing logarithms (Base 10); a list of common
mathematical symbols; 2 appendixes con-
taining logarithms and statistical tables; a
17-page glossary; and an 8-page index.

Each chapter is organized around ac-
cepted education principles. The first page
of each chapter begins either with learning
objectives organized according to the chap-
ter's subsections or a list of formulas fol-
lowed by the learning objectives pertaining
to that chapter. Pro\ided in the appendix are
solutions and answers to chapter practice
problems. At the end of each chapter is a
summary of the material and a set of chap-
ter review questions. Each chapter ends with
a bibliography.

This must have been a challenging type
of book to write. Both the breadth and depth
of detail are extensive. The need is to pro-
vide enough depth of material while remain-
ing succinct, and this book succeeds quite
well in that regard. The need to keep the
book to a single-volume limits the amount
of explanation that can be de\oted to any
one topic, so many students seeing this ma-
terial for the first time would need addi-
tional help to understand. The relevance of
the material is enhanced by the consistent
use of examples drawn from health care
fields, and especially from respiratory care.

The text is well edited, with few errors.

One potential stumbling block to success-
fully solving calculator-based problems that

use antilogarithms stems from the directions
to use the function "INV (inverse) followed
by the log key. An alternative solution should
be Micluded tor calculators that do not hav-
ing that function key. And possible confu-
sion could be prevented by slating that press-
ing the INV key followed by the log key is
one way to calculate the antilogarithm, or
that the same operation can be accomplished
by using the 10" function key.

To illustrate the challenge of balancing
depth of material with succinctness, con-
sider that, in the chapter on physiologic
chemistry, 9 organic functional groups are
presented on one page. On the next 4 pages
the stmctural formulas for a few monosac-
charides, disaccharides, and polysaccharides
are presented. Additionally within those 4
pages the Krebs cycle, coenzymes NAD*
and FAD*, net number of ATP generated,
glvcogeni>lysis. and gluconeogenesis are all
mentioned and explained to some degree.

Overall, the book fills an important niche.
For readers who desire a brief introduction
or review of the basic sciences, this book
would be a reasonable choice.

Conrad Colby PhD

Respiratory Care Department

College of Health Sciences

Boise State University

Boise. Idaho

Pediatric Pulmonary Pearls. Laura S In-
selman MD. (The Pearl Senes, Steven A
Sahn MD and John E Heffner MD, Series
Editors.) Philadelphia: Hanley & Belfus.
2001 . Sort co\er. illustrated. 224 pages. $45.

The Pearls series is a group of 13 books.
edited by Steven A Sahn and John E Heff-
ner, that covers a wide range of subject mat-
ter, including cardiology, sleep medicine,
and respiratory care, and uses case \ignettes
with discussion. This latest edition. Pediat-
ric Pulmonary Pearls, is the first pediatric
book in the series. The book consists of 70
brief case \ignettes derived from the au-
thor's pediatric pulmonary practice and that
span a wide range of pediatric lung dis-
eases. Dr Inselman is to be congratulated on
amassing such a broad array of cases. The
writing style is easy to read and in general
is clear. Each case and case discussion stands
alone, so this is the type of book that can be
hriefiy read. The cases range from congen-
ital lung diseases to inherited lung diseases
to infection to trauma. However, there is no
case of a child with asthina, so the patho-

Respiratory Care • July 2002 Vol 47 No 7

833

Books, Films, Tapes, & Software

physiology and approach lo therapy of this
very iinpoilanl iiiiii; disease are omitted.

Each case hegiiis with a hrief histoi-y and
physical examination, followed by a list of
laboratory and other test results. Many cases
include a chest radiograph or other radio-
graphic picture. A question is then asked
about the case; usually the question is what
is the best or most likely diagnosis? A di-
agnosis is then given, followed by a discus-
sion of the disease. Al the end of each dis-
cussion there is a briel paragraph on patient
therapy and follow-up. This is followed by
a list of points that the ca.se illustrates (clin-
ical pearls), then a brief list of references.

One of the strengths of this approach is
that each case can stand alone. However.
this format also presents a problem in that it
lends itself to repetitie)n and redundancy.
For example. .-^ ditf'erent cases of cystic fi-
brosis are scattered through the book.
Though different aspects of cystic fibrosis
are discussed in each of the cases, several
elements are discussed in all .■* cases. Two
cases of tuberculosis are discussed, with rep-
etition and omission. For example, in case
2. a 3.5-year-old in day care who is diag-
nosed with tuberculosis, there is no discus-
sion of the responsibility of the primary care
provider to search for the adult with active
tuberculosis nor, more importantly, how to
deal with the other children in the day care.
These are important issues for primary care
providers, who frequently ask questions
about how they should approach exposure
in other children.

The major problem with the case vi-
gnettes, however, is the lack of integration
of the case, the diagnosis, and the discus-
sion. In almost every case the discussion of
the disease does not represent a discussion
of the case itself Specifically, there is no
discussion of what elements in the history.
physical examination, or laboratory data led
to the specific diagnosis or of other possible
diagnoses. Laboratoi-y data not consistent
with the diagnosis are frei|ucnlly reported,
but why those data were obtained iuid tlic im-
plications are rarely discussed. Thus, an excel-
lent opportunity was missed, unfoiluiiately. to
offer insight into how to approach the child
with a certiiin constellation ot findings.

The book is also replete with statements
that are not quite or totally correct. For ex-
ample, in case ?>. a 9-month-old with gas-
troesophageal reflux is described as having
a hoarse cry and intermittent stridor, and the
bronchoscopy reveals normal vocal cords,
epiglottis, and carina with bronchomalacia.

Those 2 observations are not compatible. In
this same case, one of the clinical pearls is
suspect. Dr Inselman slates that "■Nocuinial
cough and whee/ing increase the likelihood
of gastroesophageal reflux." That is true only
in the presence of abnormal lower esopha-
geal sphincter tone. Coughing itself does
not lead to gastroesophageal reflux when
lower esophageal sphincter tone is normal.

In case 29. a child with gastroesophageal
reflux and hypothermia, the blood gas data
(pH 7.53. P.,c(,, 24) are not compatible with
normal electrolytes. There is no explanation
for the hypothennia. although the patient is
treated for suspected sepsis. Again, there is
no discussion of what else is going on w ith
this child.

In case 26. a child with cystic fibrosis,
the discussion states that the chloride level
in the apical surface of epithelial cells is
decreased. There is in fact considerable un-
certainty about the electrolyte content of the
apical epithelial surface. There is decreased
chloride secretion, hut whether the apical
surface of the airway epithelium is hypo-
tonic or hypertonic is not cleai-.

In case 8. a child with Duchenne's mus-
cular dystrophy, the discussion notes that
the maximum inspiratory and expiratory
pressures are abnomial in this disease, but
this patient's maximum inspiratory pressure
is -87 cm HiO. which is within the normal
range. Thus, again, the discussion does not
agree with the case.

In case 38 the alveolar air equation is
written incorrectly, and the discussion on
mechanisms of hypoxemia is confusing.
Even the choice of this case is suspect, as it
describes an extremely rare scenario, in
which a small to moderate atrial septal de-
fect with left-to-right shunt causes hypox-
emia and pulmonary hypertension.

The case review involving congenital lo-
b;u- emphysema (case 39) would have ben-
efited from a discussion of alveolar growth
and the potential effect of tlie timing of sur-
gery on alveolar development and alveoku'
number. Similarly, case 47. concerning bron-
chopulmonary dysplasia (BPD). would have
benefited from a discussion of tlie long-lcnn
sequelae of BPD on lung function and grow tli.

Another opportunity was missed in the
ca.se study of a child who ingested lamp oil.
in which the etiology of the "noisy breath-
ing" is congenital laryngomalacia. w ith the
lamp oil seen as inconsequential.

In some cases diagnoses are made when
there is no clinical history for the di.sca.se. In
case 41 (a child with fever, bibasilar pneu-

monia, and a hemoglobinopathy) the diag-
nosis is obstructive sleep apnea, without a
history of obstructive sleep apnea. In case
42, the respiratory syncytial virus rapid an-
tigen test is negative, but the diagnosis is,
nevertheless, respiratory syncytial virus. Un-
fortunately, the possible reason lor that neg-
ative test is not discussed.

The therapies described in the lollow-up
sections occasionally do not follow the
pathogenesis of the diseases, or in some
cases the therapies have been shown lo be
ineffective. For example, in case 47, a
patient who had BPD was treated with a
mast cell inhibitor therapy, which has been
shown to be ineffectixe for BPD. This
case would be misleading to a student of
pediatric lung disease.

Pediatric Pulmonary Pearls is an at-
tractive paperback. The quality of the chest
radiograph reproductions is excellent and.
in general, the radiographic abnomialities
can be seen very clearly. Some of the cases
have very old references, dating from the
1960s and 1970s, whereas others are cur-
rent. The index is good and thus it is easy to
find cross-referenced cases. The text is
clearly written and with minimal typo-
graphic and spelling errors. Illustrations of
pathology findings would have enhanced
some of the cases. The book is intended for
clinicians at all levels of training and expe-
rience. It has both common and unusual di-
agnoses and thus will appeal both to the
student and to the specialist. The respiratory
therapist who has an interest in diagnosis of
pediatric lung disease will find the case vi-
gnettes and discussion interesting.

In summary. Pediatric Pulmonary Pearls
will be of interest to clinicians. The cases
are interesting and illustrative of the wide
range of pulmonary diseases in children. De-
spite some limitations, the broad strokes of
the discussions are good and will serve as a
beginning place for the student of pediatric
lung disease.

Michelle M Cloutier MD

Asthma Center

Connecticut Children's Medical Center

Department oi Pediatncs

University of Connecticut

Hartford. Connecticut

Teaching in Your Office: .\ Guide to In-
structing Medical Students and Resi-
dents. Patrick C Alguire MD. Dawn E De-
Wiit MD MSc. Linda E Pinsky MD. and
Gary SFerenchickMD. Philadelphia: Amer-

834

Respiratory Care • July 2002 Vol 47 No 7

Books, Hums. Taim.s, & Soitware

ican College of Physicians. 201)1. Soft-
cover. 145 pages. $2.5.

Il is often said that "Those u ho can. Jo;
and those who can"t. leach!" Ttachin!; in
Your Orfice: .\ Giiick' lo Inslructiiis Mcd-
ital Students and Rcsident.s is a timely
and very readable "how to" book that would
make good teachers of all of us in the "can
do" category. It also has something to offer
those of us v\ ho ha\ e been teaching all along.

For the first decade oi' m\ career ni pri-
mary care internal inedicine I practiced solo,
and the only teaching I did was while on the
wards at the hospital. In the past decade I
have been teaching extensively in my urban
community -based office. At any gi\en time
my 3 associates and I in some combination
deliver primap,' care and internal medicine
c;ire to our patients. In doing so. we accom-
modate 2 post-graduate-year-2 residents and
1 medical-school-year-4 student. The trick
is to pull it off effectively using all 6 of our
exam rooms! The trial and error method
was employed.

Over the years our community-based teach-
ing program has evolved. Methods that work
for some of us do not work as well for others.
.Some of us ha\e trainee presentations made to
us in the hallway, whereas others prefer to im-
prove efficiency and have the trainee presen-
tations made in the exam room with the pa-
tient. I am not sure any 2 of us use similar
methcxis to v\rite trainee evaluations.

As more and more residents (and now
students too) signed up for our '"Ambulato-
ry Medicine Experience." we discovered a
need for a tbrmal orientation policy/proce-
dure booklet for them to read on their first
day. This addition streamlined orientation
for the trainees on a number of issues, such
as charting and chart organization, office
note procedures, dictation procedures, lab-
oratory requisitions, phlebotomy, pulse oxim-
etry, electrix-'ardiography. urinalysis, skin bi-
opsies, vaccinations, and health maintenance
issues.

At month ' s end. preceptors evaluate train-
ees and trainees evaluate their experience.
Everybody seems to be happy. I can tell
that each of the trainees has truly learned as
much art as skill in the month. 1 know first-
hand how sharp I feel that 1 need to be
around them. A re\ iew of the evaluations
from both sides supports my contention that
our method is a resounding success!

Given that background, how skeptical I
was to undertake this book review. Would
the book be an arcane dissertation replete

with medical education niles generated from
controlled clinical trials about teaching.'
Would il be practical to gi\e the book lo an
attending physician who was a novice al
community-based teaching? Would the
book have anything in it for me?

My concerns and questions were all fa-
vorably answered. On the one hand. I felt
vindicated that we had stumbled onto many
ot the good training methods de.scribed by
the authors. On the other hand. I found there
were areas that could be improxed in our
own endeavor. I don't believe that any new
group who wishes to teach in the office
should have to reinvent the wheel, as we
did; |usl read this book' It's that simple.

Teaching in \'(>ur OfTice is a 92-page
soflbound book v\ritten in very plain lan-
guage, with very simple thoughts, recom-
mendations, and recipes for how to perform
the manv duties we undertake when we com-
mit to follow Hippocrates" s Oath and teach.

The book is very well written and edited,
and its structure is simple and logical. A
short preface literally itemizes "the bottom
line"' of each of the book's 8 chapters. The
chapters fall in logical sequence, as evi-
denced by their self-explanatory titles: Mak-
ing an Informed Decision about Precepting:
The CuiTiculum; Getting Ready to Teach:
Teaching Skills and Organizational Tech-
niques for Office-Based Teaching; Case-
Based Learning: Ways to Be More Effi-
cient When Teaching: Learner Feedback and
Evaluation; and Preceptor Evaluation and
Teaching Improvement.

Each chapter offers clear and concise rec-
ommendations concerning the issue at hand.
References to the literature are appropriate
and not overbearing in number. I finished
each section with a clear idea of how to do it
right ;uid with a feeling that it was feasible to
do it right w ithout sacrificing office efficiency.

The book's organizational approach is
clear and complemented by Appendix A,
which catalogs all of the important infor-
mation in the substance of the chapters into
checklists that can be copied and used on a
daily basis to assure an excellent teaching
environment, all the while that good clinical
medicine is delivered. There is a "Before
the Learner Arrives"" checklist. '"Summarv'
of the Learning Experience" checklist, short
descriptions of each of the teaching models
proposed, and a I -page review of the RIME
(reporter, interpreter, manager, educator)
evaluation method.

Appendix B provides 1-page tools that
prompt the preceptor to provide an excel-

lent learning environment without disrupt-
ing normal clinical activities or revenues.
These tools include a checklist of clinical
skills inventory, a learner contract, a sample
notice for the waiting room describing the
presence and role of the student, sample
tools to help the learner organize the visit.
sample presentation lormats. an educational
prescription form, preceptor evaluation
form, and a patient satisfaction form.

Some important resources for the
would-be teacher are detailed in Appendix
C. Faculty development programs and vid-
eotapes are described. There are national
recognitions and awards available to those
who commit to the regular practice of of-
fice-based teaching.

I must say that the exercise of reviewing
this book has produced changes in my own
teaching enterprise. Some concepts were fa-
miliar to me. but the existence and merits of
other ways to teach was news. I also bene-
fited immensely from the very specific rec-
ommendations about the evaluation process.
Finally. I found very valuable the occasional
tips given in shaded areas throughout the
book; these sidebars illustrated important
teaching points and gave examples of how
not to interact with the trainee if an optimal
learning environment is the goal.

In all, I recommend this book enthusias-
tically to practitit)ners of any specialty who
wish to teach medical students or residents
in the outpatient setting. Like everything else
in life, there are right ways and wrong ways
to go about the same tasks: this book makes
it simple to do it the right way. The great
demand for community-based teachers is
high and increasing. More and more pro-
grams me looking to give their residents and
students substantial exposure to outpatient
medicine, and there are simply not enough
doctors willing and able to take on the task.
These factors increase the need for this book,
which demonstrates that teaching in your
office can he done, can be done well, and
can be done in a mutuallv satisfying way
w ithout disaipting clinical activities and eco-
nomic stability. Everybody wins!

Mark G Graham MD

Jefferson Medical Care

Division of Primary Care Internal

Medicine

Depailmenl of Medicine

Thomas Jefferson University

Philadephia, Pennsylvania

Respiratory Care • Ki\ 2002 Vol 47 No 7

835

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__^tiAssoe

Audio Cassette Tapes

from the

47th International

Respiratory Congress

I Tape = $10 each

2-5 Tapes = $9.50 each
6 or More = $9 each

Show Special... Pick any 12 tapes with free storage album for $99!

SATURDAY. Dec. I

J I . Kcynolc Address. D. Satcher

J 5 Trucking Flow ot Residents. D.N. Muse

_1 b. (6.) Role ot Educators. E.A. Becker &

(7.) Role of Managers. K.J. Steuan &

(8.) Panel Discussion. M.Trahand

□ 9. Errors. Law and RCPs. A.L. DeWiti

Q 10. Human Error: Changing Our Perceptions. J.W. Salyer

□ II. Patient Abuse in the Home: What Is It and What Are Your
Responsibilities' D. Roberts

□ 12. Assessing the Right Competencies lor Home Care Therapists,
S.L. Moreau

□ 13. Discharging the Complex Pediatric Patient to the Home. J. P.
Stegmaier

□ 14. Does Economics Dri\e Home Care ' R.W. McCoy

□ 15. Surfactant Therapy. R.J. Rodriguez

□ 16. Neonatal Update: Inhaled Nitnc Oxide in the Neonate. S.R. Seidner

□ 17. Mgt. Strategies for Prevention of BPD. R.J. Rodriguez

□ 18. Over\iew of Dying and End-of-Life Care in America. PA. Selecky
G 19. Withholding and Withdrawing Ventilation. R. ,\ce\edo

□ 20. Role of the RespiratoA Therapist in Palliative Care. H.M. Sorenson

□ 21. (21.1 Building Coalitions. J. B. Fink
(22.) Reaching Patients and Physicians with "Baylor's Rules of
Two"!. G.E. Lawrence

□ 23. (23.) Regional Asthma Center. L. Parish-Cooper
(24.) Promoting Public Awareness: Successful Strategies, S.
Blonshine

□ 25. (25.) Sleep Disordered Breathing, M.B. Dunning III
(26.) Protocols for Standardized Sleep Testing, R.N. Turner

Q 27. (27.) New Polysomnoeraph Technologist Training Guidelines,
R.N. Turner
(28.) Survival Techniques for Shift Workers. M.B. Dunning

□ 31 A. Issues & Trends in Allied Health Leadership. M. Harrington.
Developing Your Career for Maximum Professional
Effectiveness. M. W. Runge

Breakout #1: Leadership in Clinical Practice. G. Gaebler
Breakout #3: Leadership in Management. J.D. Kimble (Needs
overtime tape)

□ 31 B. Developing Professional Leadership. R. Krueger
Success Stories, J.C. Bolden . D. Johnson

□ 31 C. #2: Leadership in Clinical Research. A. B. Adams &
#4: Leadership in Education. L. Van Scoder

□ 34. Humor at the Bedside, M. Graves
SUNDAY. Dec. 2

□ 53. Selecting Fiscal and Salislaction Outcomes in LTOT. T.W. Buck

□ 54. Measuring and Collecting Outcome Data, D.C. Shelledy

□ 55. Using LTOT Outcome Data. R. Fary

□ 56. Outcome Data Panel Discussion, T.W. Buckley, R. Fary, T.L.

Petty, and D.C. Shelledy

□ 57. Smoking Cessation. D.D. Gardner

□ 58. New Strategies for Treating Tobacco Use and Dependence, R.(

Cohn

□ 59. How Respiratory Care Managers Can Implement Tobacco

Education Programs for Community-Wide Effect, S.M. Ciarlarii

□ 60. Secondhand Smoke — What Can Health Care Professionals 1)

About It? A. French. B. Hutfman

□ 61. (61.) Evolution and Rationale of the Low VT Protocol. R. Brow

(62.) Practical Aspects of Implementin'j the Low VT Protocol,
Kallet

□ 63. (63.) Can the ARDS Network Protocol Be Modified?, N.R.

Maclntyre &

(64.) How and Why to Use Recruitment Maneuvers in Low V

Ventilation. N.R. Maclntyre

□ 65. (65.) Normal Mechanisms of Airway Clearance and Problems

from the ICU to Home. B.K. Rubin &

(66.) Positioning vs. Postural Drainage. J. Fink &

(67.) Breathing Maneuvers, M. Maclllwaine

□ 68. (68.) Positive Pressure Techniques for Airway Clearance, M.J.

Mahlmeister &

(69.) High Frequency Oscillation of the Airway and Chest Wal

J. Fink &

(70.) Airway Clearance and the Artificial Airways, R. Lewis

□ 71. (71.) Pharmaceutic Approach to Airway Clearance. B.K. Rubin

(72.) Strategies for the Pediatric Patient. K.L. Davidson &
(73.) Airway Clearance Strategies for the Vent Patient at Homt
C. Lapin

□ 74. RSV: Management and Treatment Advances, CM. Kercsmar

□ 75. Test Your Skills on the State of the Profession. M.F. Traband

□ 76. How to Survive as a Multi-Department Manager, S.J. Price

□ 79. Technological Advances in Nonin\asive Respiratory Monitorii

G. Devine

□ 80. Monitoring on the General Floor: What"s the Future Going To

Like? PT. Sharkey

□ 81. A Proposal for Evidence-Based Practice in Neonatal

Resuscitation, W.D. Rich

□ 82. Classifying Asthma Patients through Symptom Analysis, T.J.

Kallstrom

□ 83. How Not to Run a Respiratory Care Service, K.L. Shrake
MONDAY. Dec. 3

□ 84. Kittredge Lecture — Mechanical Ventilation: How Did We Ge

Here and Where Are We Going?, R.D. Branson

□ 85. Intrapulmonary Percussive Ventilation. C. Diaz

□ 88. Exercise Training: Are You Training Your Patients at the Righi

Exercise Target? B.W. Carlin

□ 89. Water Exercise in Pulmonary Rehabilitation Programs, M.W. Mil
D 90. The Impact of the Institute of Medicine's Report for Rcspirato

Care Providers, S.P. Giordano

□ 91. Evidence-Based Respiratory Care, D.J. Pierson

□ 92. Managing Chronic Medical Conditions in the New Care Deliv

Framework, P.J. Dunne

□ 93. (93.) .Applying Case Management Principles in Home Care, J.l

Stegmaier &

(94.) Developing a Cost Model For Deli\ery of LTOT. T.W. Buck
_l 95. (95.) What I Wish All Home Care Therapists Knew, B. Rogers, i
(96.) LTOT Utilization: The Bigger Picture! G. Spratt

□ 97. (97.) Modifying Treatment Plans For the Aging Lung, T.S.

LeGrand &

(98.) Seeing Health Care through the Eyes of the Elderly, HM

Sorenson

□

141

□

142

143

144

145

146

□

147

□

144

150

J 49. (94.1 C;iriii!2 loi ihc Oklcr I'neiinuini;! Patient, T.S. LcGrand & _l 140.

( 100.1 Senior I'uliimnaiv Assessment, H.M. .Siirenson
J 101. Inlerprelalion of PlTs hy RCPs. J.O. NilsesUien
J 102. Results ol a National .Study. J.M. Boyle
J 10.^. .Agenev L'pdates n riiroui;h the eves of the A ARC, ARCF,

CoARC and NBRC. CP.'wie/ali's. M.T. Amato. M. Weleh Jr.

and J. Long-Ciodiny
^ 104. Munehausen hy Proxy. D. Roherts

G 105. Opening the Blaek Bo,\ during Meehanical Ventilation. M. Amato
3 107. ( 107.) Documenting Respiratory Practice Beyond the USA. J.

l.ong-Goding H.I,, (iar/a &

( 10<S.| Comparison of Two Methods for Administration of

Inhaled Salhutamol, H.I,. Molina
J 109. 1 109.) The Brazilian l-.\penence, L.G. Ghion &

I 1 10.) The Inited Kingdom K.xperience. A. Hynes
J 111.(111.) The Italian hxperience. S. Thompson &

(112.) The Japanese Kxperience. H. Etchuya
J 1 13. ( 1 13. )The North America Experience. A. King & □ 152.

(114.) The Personal Experience — A Patient's View. B. Rogers.

& Panel Discussion
G 115. Creating an Elfecti\e Multi-Cultural Work Environment, K.L.

Shrake

116. Bronchiolitis Care Path. J.W. Salyer

1 1 7. Pediatric Asthma: Success with Therapist-Driven Protocols. T.R. □ 155.
Myers

118. Developing a Pediatric Consult Program, J.W. Salyer

1 19. Lung Protective Strategies for Status Asthmaticus. M.K. Brown

120. Acute Care of the Adult Asthmatic. J.I. Peters

121. Bronehodilator Resuscitation in the ER. J. Fink

122. Case Presentations of Pulmonarv X-Rays. C.G. Durbin
123.( 123.) PA' Curves Should Be Routinely Used in Ventilatory

Management of ALI, K. Hargett, R.M. Kacmarek &

(124.) Heliox is the Front-Line Treatment for Management of

Acute Asthma. T.R. Myer. CM. Kercsmar

125. New Modes of Mechanical Ventilation Are Necessary for
Manageinent of Patients w ith ARE. N.R. Maclntyre. R.D.
Branson

126. Oxygen Toxicity in the ICU Is a Myth. D.J. Pierson. C.G. □ 166,
Durbin Jr

131. An Answer to Respiratory Care Re-Engineering. D.C. Oberly

132. What's Right and What's Wrong with Cardio-Pulmonary
Exercise Tests. M.W. Millard

133. The Amazing History of Pulmonary Medicine. G.W. Lantz

134. New Uses for an Old Therapy. M.K. Brown
TUESDAY. Dec. 4
3 1 35. Which One for ARDS.' M. Amato

□ 136. What It Is and How You Can Help. R.R. Eluck

□ 1 37. Prospective Payment Svstem(PPS) □ 173.

□ 1 38. Models of Success for RCPs. K.A. Cornish
J 1 39. Wave Form Analysis. J.O. Nilsestuen

□

156

□

157

□

158

□

159

160

161

□

164

□

165

167

□

168

□

169

□

170

□

171

□

172

Diagnostic Testing: Pre- and Post-Lung Transplant. CM. Foss

Lung Transplantation from the Patient's Perspecti\e. M. Pierce

Apples to Apples: First Line Therapy. S. Jenkinson

Safety of First Line Options. TA. Mahr.

Advantages of Combination Therapy. J. Bloom

.Advances in Delivery: Does Particle Size Matter'.' TA. Mahr

NPPV Without Quantifiable Evidence: The Legal and Medical

Ramifications. PK. Blakely

Using Protocols in Respiratory Home Care, G. Spratt

Telemedicine and the Hcmie Care Respiratorv Therapist. P.K.

Blakely

Corporate Compliance Plan: What the OIG Is Really Saying. P.

Dunne

( 150.1 How To Come L'p with a Good Research Question. C.G.

Durbin Jr &

(151.) How to Get a Research Project Done in 'Vour Departmen

J. Ward

(152.) How to Write an Open Forum Abstract That Will Be

Accepted. D.J. Pierson &

( 153.) How to Make an Effective Poster for Presentation at the

Open Forum. D.C. Shelledy &

(154.) How to Prepare and Deli\er an Eflccti\e Oral. Summary

of Your Project, R.S. Campbell

Pulmonary Hypertension and the Respiratory Therapist. R.L.

Rosenblatt

Management of Amyotrophic Lateral Sclerosis. C.E. Jackson

Insight to the Profession. Panel

Weaning from Mechanical Ventilation. N.R. Maclntyre

Treatment of the -Adult Patient w ith Cystic Fibrosis, R.L.

Rosenblatt

Recent De\elopments in the Management of Meconium

Aspiration, R. Castro

Critical Diagnostic Thinking for Respiratorv Therapists. DC.

Shelledy

Pharmacology and Patient Safety. J.H. Eichhorn

Non-invasive Monitoring durins: Procedural Sedation. D.H.

Walker

Procedural Sedation in the ER: The Role of the Respiratory

Therapist. B. Krauss.

Airway Remodeling: To Do or Not To Do? N.A. Hanania

Neonatal Critical Care Transport. H. Heiman

Neonatal Transport Cases. S. Segovia

A&B (2 Tapes) .Allergic Disorders: The Child with Rhinitis anc

Asthma. B. Martin

What's New in CPR ALS'? T.A. Barnes

Recentralized Respiratory Senices: Ten Things We Learned

from Our Customers. G.F. Ellis

.A Respiratory Therapist Could Ha\e Sa\ed President George

Washinalon. D.J Pierson

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American Association for Respiratory Care

MEMBERSHIP APPUCATION

ACTIVE MEMBER

An indivdual •- eligible i* ne she tives in the U.S. or its territories or was on Active Member
pnof to moving outstde its borders or territories, ond meets ONE of the following crileno: (l)
IS legolly creaenlioled as o respiratory core professional if employed in a state that
mcndotes such, OR (2) is a graduote of an accredited educational program in respiratory
core OR [3) holds a credenfiol issued by the NBRC

ASSOCIATE OR SPECIAL MEMBER

Individuals who hold a position related to respiratory care but do not meet the requirements
of Active Member shall be Associate Members, They have all the rights and benefits ol the
Association except to hold office, vote, or serve as chair of a standing committee The
following subclasses of Associate Membership ore available Foreign, Physician, ond
Industrial (individuals whose primary occupation is directly or indirectly devoted to the
manufacture, sale, or distribution of respiratory core equipment or supplies} Special
Members ore those not working in o respirotory core-reloted field

STUDENT MEMBER

Individuals will be clossified as Student Members if they meet all the requirements for
Associate Membership and are enrolled in an educational program in respiratory care
accredited by, or in the process of seeking occreditotion from, on AARC-recognized agency

SPECIAL NOTICE — Student Members do not receive Continuing Respiratory Care
Education (CRCE) transcripts Upon completion of your respiratory core education,
continuing education credits may be pursued upon your reclassification to Active or
Associate Member

Please read the eligibility requirements for each of the classifications
above, then complete the form. All information requested must be
provided, except v^here indicated as optional. See other side for more
information and fee schedule. Please sign and dote application on reverse
side and type or print clearly. Processing of application takes
approximately 15 days.

n Active
Associate

_ Foreign

D Physician

D Industrial
n Special
a Student

Last Name

First Name

Social Security No.
Home Address

Would you like to receive our monthly newsletter, AARC Report,
by email?

u Yes D No

Have you ever been or are you currently in the military?
L Yes D No

Demographic Questions (optional)

We request that you ansv/er these questions in order to help us design
services and programs to meet your needs.

Primary Job Responsibility (check one only)

C Director (Technical or Program| L.i Therapist/Technician

□ Supervisor T 1 Medical Director

D Diagnostic Technologist 1 Student

D Instructor/Educator H Staff Nurse

11 Other, specify

Type of Business

__ Educational Institution
G DME/HME
D Home Health Agency
D Hospital/Acute Core
n Other, specify

Manufacturer or supplier
Outpatient Clinic
I Physician office
D Skilled Nursing Facility

Check the Highest Degree Earned

„ High School , Bachelor's Degree

n RC Graduate Technician C Master's Degree

D Associate Degree D Doctorate Degree

Number of Years in Respiratory Care

^ 0-2 years ^ 11-15 Years

D 3-5 years D 16 years or more

n 6-10 years

Job Status

Full Time

D Port Time

City.

Stole

.Zip

Phone No.

You are automatically assigned to a stole society based on your home
oddress. If you wish to be assigned to a different state society, please
indicate v/hich state thot is here:

Work Information:

Place of Employment

Address

City

State Zip -

Phone No

Preferred Fox No.(

Preferred Email Address _
Preferred mailing oddress:

D Home

Credentials

_ RRT
D CRT
D Physician
D CRNA
D RN

Date of Birth

Sex

D LVN/LPN

D CPFT

D RPFT

D Perinotal/Pediatric

FOR STUDENT MEMBER - REQUIRED

School/RC Program

Address

City_
State

.Zip

Phone No

Expected Date of Graduation (required information)

Month Year

American Association for Respiratory Care • 11030 Abies Lane • Dallas, TX 75229-4593 • [972] 243-2272 • Fax [972] 484-2720

American Association for Respiratory Care MEMBERSHiP APPLtCATtON

Membership Fees

Payment must accompany your application to the AARC. Fees are
for 12 months. These fees contain the $12.50 new members
processing fee. Renewing members (except students] can deduct
$12.50.

CHOOSE ONE LEVEL OF MEMBERSHIP

AARC REGULAR MEMBERSHIP (Receive both AARC Times and
Respiratory Core journal)

□ Active $102.50 —

□ Associate (Industrial or Physician) $102.50
D Associate (Foreign) $117.50
D Special $102.50
a Student $ 50 00

AARC CHOICE MEMBERSHIP(Choose one publication)

„ Active $ 91.00

D Associate (Industrial or Physician) $ 91.00

D Associate (Foreign) $106.00

n Special $ 91.00

I want 1_ AARC Times L Respiratory Care journal

AARC PLUS MEMBERSHIP (All publications and other items)

_ Active $137.50

D Associate (Industrial or Physician) $137.50

D Associate (Foreign) $177.50

□ Special $137.50-

(Includes one free section ■ please mark choice below.)

Specialty Sections (optional)

Established to recognize the specialty areas of respiratory core,
these sections publish a newsletter four times a year that focuses on
issues of specific concern to that specialty. The sections also design
the specialty programming at the national AARC meetings.

D Adult Acute Core Section

n Education Section

D Perinatal-Pediatric Section

n Diagnostics Section

D Continuing Care-
Rehabilitation Section

n Management Section

n Transport Section

n Home Core Section

n Subacute Care Section

$15.00-
$20.00
$15.00
$15.00

$15.00
$20.00
$15.00
$15.00
$15.00-

PLEASE SIGN

I hereby apply for membership in the American Associotion for Respiralory Care
ond hove enclosed my dues, If approved for membership in the AARC. I will
obide by its bylaws and professional code of ethics I authorize investigation of
ail statements contained herein ond understand thot misrepresentolions or
omissions of focts colled for is cause for rejection or expulsion.

A yearly subscription to RESPIRATORY Care journal ond AARC Times magazine
includes on ollocotlon of $1 1 ,50 from my dues for each of these publicotions

NOTE Contributions or gifls to the AARC are not tax deductible as charitable
contributions for income tax purposes- However, they may be tax deductible as
ordinary and necessary business expenses subject to restrictions imposed as a
result of association lobbying activities. The AARC estimates that the
nondeductible portion of your dues — the porlion which is allocable to lobbying
~ is 26%

Signature
Date

TOTAL MEMBERSHIP FEE $_

TOTAL SECTION FEE $_

GRAND TOTAL = Membership Fee

plus optional sections

" Total Amount Enclosed $

Please charge my

dues (see

below)

To charge your dues,

complete

the

following:

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Sianature

Mail application and appropriate fees to:
American Association for Respiratory Care • 11030 Abies Lane « Dqllos, TX 75229-4593 • [972] 243-2272

Fax [972] 484-2720

RE/PIRATORy QVRE

Manuscript Preparation Guide

Respirator'V' Carh welcomes original manuscripts related to the sci-
ence ;ind technology ot'a'spiratoiy care and prep;ired according to the
follow ing instnictioiis and the Vnitonu Rciiiiiiviiwnis for Miiini.scripls
Siihniirtcil III BiomediciilJoiiniais (available at lntp://\\\\w:iciiiji'.orii/
imkx.htinl). Manuscripts are blinded and reviewed by profession-
als with experience in the subject of the paper. Authors are respon-
sible for obtaining written peniiission from the original copsrlghl liold-
er to use pre\ lousl) published figures and tables. Before publication.
authors receive page proofs and are allow ed to make only minor cor-
rections. Accepted manuscripts are copy-edited for cUuily. concision.
and consistency with RH.SPIR.ator^ Care's format. Published
papers are copyrighted by Daedalus Inc and may not be published else-
where w ithout pemiission. Editorial consultation is available at any
stage of planning or writing: contact the Editorial Office. 600 Ninth
Avenue, Suite 702. Seattle WA 98104. (206) 22.V()558. fax (206)
223-0563. E-mail: rcjoumal(§^aarc.org

Categories of Articles

Research Article: A report of an onginal investigation (a study). Must
include: Title Page. .Abstract. Key Words. Introduction, Methods.
Results. Discussion. Conclusions, and References. May also include:
Tables. Figures (if so. must include Figure Legends). Acknowledg-
ments, and Appendixes.

Review: A comprehensive, critical review of the literature and state-
of-the-art summary of a topic that has been the subject of at least 40
published research articles. Must include: Title Page. Outline.
Abstract. Key Words. Introduction. Review of the Literature. Sum-
mary, and References. May also include: Tables. Figures (if so. must
include Figure Legends). Acknowledgments, and Appendixes.

Overview: A critical review of a pertinent topic that has fewer than
40 published research articles. Same structure as Re\ iew Article.

Update: A report of subsequent developmenls in atopic that has been
critically reviewed in RESPIR.'XTOR'i C.\RE or elsew here. Same struc-
ture as a Review Article,

Special .\rticle: A pertinent paper not fitting one of the other cate-
gories. Consult w ith the Editor before writing or submitting such a
paper.

Editorial: ,\ paper addressing an issue in the practice or administration
of respiratory care. It may present an opposing opinion, clarify a posi-
tion, or bring a problem into focus.

Letter: A brief, signed communication responding to an item pub-
lished in Respir.atory Care or about other pertinent topics.
Tables. Figures, and References may be included. The letter should
be marked "For Publication."

Case Report: Report of an uncommon clinical case or a new or
impnned method of m;magement or treatment. A case-m;uiaging physi-
ci;m must either be ;m author or furnish a letter apprin ing the m;uiiiscript.
Must include: Title Page, Abstract, Key Words. Introduction, Case
Sumniiuy, Discussion, and References. May also include: Tables, Fig-
ures (if so, must include Figure Legends), and .Acknowledgments,

P()int-of-Vie\v: A paper expressing personal but substantiated opinions
on a pertinent topic. Must include: Title Page, Text, and References. May
also include: Tables and Figures (if so, must include Figure Legends),

Drug Capsule: A miniature re\ iew pa[X"r abotit a dnig or class of dmgs.
Drtig Capsules address pharmacology, ph;iniiacokinetics, and/or phar-
macotherapy.

(iraphics Comer: A brief, insuuctive case report discussing and illus-
trating waveforms for monitoring or diagnosis. Must include: Ques-
tions, Answers, and Discussion,

PFT Corner: A brief, instniclive case report arising from pulmonary
function testing, accompanied by a review of the relevant physiolo-
gy and appropriate references to the literature. Must include: Ques-
tions, Answers, and Discussion.

Test Your Radiologic Skill: A brief, instructive case report pertinent
to respiratory c;ire ;uid in\ol\ ing imaging, including one or more radio-
graphs or other images submitted as black and w liile glossy photographs
that clearly illustrate the teaching points being made. Must include:
Questions. Answers, and Discussion.

Preparing the Manuscript

Double-space the text and number the pages. Do not include author
names, author institutional aftlliations, or allusions to institutional affil-
iations anywhere except on the title page. On the Abstract page include
the title but do not include author names. Begin each of the follow-
ing on a new page: Title Page, Abstract, Text. Acknowledgments. Ref-
erences, each Table, each Figure, and each Appendix. Use standard
English in the first person and active voice. Type all headings in ini-
tial-capital letters (eg. Introduction, Methods, Patients, Equipment,
Statistical Analysis, Results, Discussion). Center the main section head-
ings and place second-level headings on the left margin.

.Abstract. Please ensure that the abstract does not contain any facts
or conclusions that do not also appear in the Nxly text. Limit the abstract
to no more than 2.50 words.

Key Words. Include a list ol 6 to 10 ke> words or key phrases in
Research Articles, Reviews. Overviews. Special Articles, and Case
Reports. Key words are best selectetl from the Meilical Subject Head-
ings (MeSH ) used by MEDLINF) and available at lmp://w\\\\.nlm.iuh.
f;or/iiu'.sh/iiU'slih<itiu\liliiil.

RESPIRATOR"! Cari; Manuscript Preparation Guide. Revised 4/01

Manuscript Preparation Guide

References. Assign rdciviicc luiiiibcis in the order thai articles are
eited in voiir nianiiscript. At tlie end ol the manuscript, hst the cited
works in niimeiical t)rder. Ahbre\ iale jouniai names as in Index Medi-
ciis. List all authors. It'tlie rese;irch has not set been accepted for pub-
lication, ciie the research as a personal communication (eg.
.Smith KR. personal communication. 20()l ): however, you must obtain
written pennission from the author to rite his or her impiMislied data.
Do not number such references; instead, make parenthetical reference
in the bod>' text of your manuscript. Example: "Recently, Jones et al
found this tfeatment effective in 45 of 83 patients (Jones HI. personal
communication. 2000).""

Corporate author book:

.American Medical Association Department of Drugs. AMA
drug evaluations. 3rded. Littleton CO: Publishing Sciences
Group; 1477.

Chapter in book with editor(s):

IsonoS. Upper airway muscle function during sleep. In: L<iugh-
lin GM. Carroll JL. Marcus CL. editors. Sleep and breathing in
children: a de\elopmental approach. (Lung Biology in Health and
Disease. Vol 147. Claude Lenfant, Executive Editor.) New
York/Basel: Marcel Dekker; 2000:26 1-291.

The following examples show RKSPIRATORY Care's style
for references.

Paper accepted but not yet published:

Hess D. New therapies for asthma. Respir Care (year, in press).

Article in a journal carrying pagination throughout the volume:
Legere BM, Kavuru MS. Pulmonary function in obesity.
Respir Care 2000;45(8);967-968.

Article in a publication that numbeis each issue beginning with Page 1 :
Kallstrom TJ. Focus on asthma — disea,se management: a role for
the respiratory therapist. AARCTimes I999;2.3(Oct):16, 17, 19.

Corporate author journal article:

American Association for Respiratory Care. Clinical Practice
Guideline. Removal of the endotracheal tube. Respir Care
1999.44(1 ):8.S-90.

Article in journal supplement: (Journals differ in numbering and iden-
tify ing supplements. Supply infoniiation sufficient to allow retrieval.)
Barnes PJ. Endogenous inhibitory mechanisms in asthma. Am
J Respir Crit Care Med 2()()(); 161(3 Pt 2):S176-S181.

Abstract in journal: (Abstracts citations are to be avoided, and those

more than 3 years old should not be cited.)

Volsko TA, De Fiore J. Chatbum RL. Acapella vs flutter: per-
formance comparison (abstract). Respir Care 2000;45(8):99l.

World Wide Web

American Lung Association. Trends in pneumonia, influenza, and
acute respiratory conditions mortality and morbidity. Febiii;ir\; 2(XX).
http://www.lungusa.org/data. Accessed November 20. 2()()0.

Tables. Tables should be consecutix ely numbered. At the bottom
of the table define and/or explain all abbre\ iations and symbols used
in the table. For footnotes use the follow ing symbols, superscnpted,
in the table body, in the following order: *. t. %. §. ||. % **. tt. If
data include a ■"±" value, please indicate whether the \ alue is a stan-
dard deviation or standard error of the mean.

Figures (illustrations). Figures include graphs, line drawings, pho-
tographs, and radiographs. .Ml figures should be sharp black-and-
white images and be camera-ready. Glossy prints are preferred, but
a good la.ser print will do. Use only illustrations that elaiify and aug-
ment the text. Radiographs should clearly illustrate the point being
made ;ind should be submitted a.s black-and-white glossy photographs.
If color is essential to the figure, consult the Editorial Office for
more information. In reports of animal experiments, use schemat-
ic drawings, not photographs. A letter of consent must accompa-
ny any photograph of an identifiable person. Number figures con-
secutively as Figure 1 . Figure 2. etc. All the figures must be mentioned
in the text. Every figure must have a legend (a title and/or descrip-
tion explaining the figure). Figure legends should appear as sep-
arate paragraphs at the end of the manuscript (after the References
section), in the same computer file as the manuscript (not in a sep-
arate file, as with the tables and figures).

Editorial in a journal:

Giordano SP. What's that sound? (editiirial) Respir Care
2000;45(10):1 167-1 168.

Editorial with no author given:

The perils of paediatric research (editorial). Lancet
1999;353(9I34):685.

Letter in journal:

Piper SD. Testing conditions for nebulizers (letter). Respir Care
2000;45(8):971.

Book: (For any book, specific pages should be cited w hene\'er ref-
erence is made to specific statements or other content. )

Cairo JM. Pilbeam SP. Mosby's respiratory care equipment. 6th

ed. St Louis: Mosbv; 1999:76-8.3.

Do not create scanned sersions of figures borrowed fn)m other pub-
lications; clear photocopies are preferable. To include figures pre-
\ iously published in other publications you must obtain pennission
from the original copyright holder. Figures must be of professional
quality and a copy of the article from w hich the figure came should
be available.

Drugs. Precisely identify all drugs and chemicals used, giving gener-
ic (nonproprietary) names, doses, and methods of administration.
Brand or trade names may be given in parentheses after generic

names.

Commercial Products. In the text, parenthetically identity com-
mercial products only on tlrst mention. gi\ ing the maiiufaclurcr"s
name and location. Example: "We pert'onned spirometn ( 108.3 Sys-
tem. Medical Graphics. Minneapolis. Minnesota!" Punide model

Respir AlOR'i C.\RH Manuscript Preparation (juide. Revised 4/01

Manuscript prkpakation Guidi-

numbers il aNailahlc. and rnaiuitai-'tiirci'N sLiggcstcd piui.- illlic sluils
has CDM implications.

Permissions: You nnisl ohiani wriucn permission lo use pieliires
of idenliriable indi\ idiials or lo name indi\ idnals in llie Aekiiow I-
edgnienls section, ^'ou must obtain written permission Ironi llie
original copyright holder to use figures or tables from other pub-
lications. Copies of all applicable permissions must be on file at
RliSPIR.MOR^' C.\Kh before a manuscript goes to press. Copyright
is most often held by the Journal or book in which the figure or table
originally appeared and applies to the creativity, style, and form
in which the facts/data are presented lo the reader: the facts ihcm-
sehes are not copyiight-proleclahle. Therefore, pennission is required
to reproduce a table or figure directly, or with minor adaptations,
from a journal or book, but permission is not re(.|uired il data are
extracted and presented in a nev\ fomiat. In that case, cite the source
of the data as in the following example: "Adapted trom Reference
23."

Ethics. When reporting experiments on human subjects, indicate that
procedures were conducted in accordance with the ethical standards
of the World Meiticcil Association Declaration oJHelsinkHsee Respir
Care 1997:42(6):635-636: also available at http.V/www.wina.net/e/
J7-c_einn-(i\irapliniinilH'rini;. html) or of ihe institution's committee
on human experimentation. State that informed consent was
obtained. Do not use patients" names, initials, or hospital numbers in
text or illustrations. When reporting experiments on animals, indicate
that the institution's policy, a national guideline, or a law on the care
and use of laboratory animals was followed.

Statistics. Identify the statistical tests used in analyzing the data and
give the prospectively detemiined level of significance in the Meth-
ods section. Report p v alues in tlie Results section. Cite only textbook
and published article references to support choices of tests. Paren-
theticallv identify any computer programs used. If data include a "±"
value, plea.se indicate w hether the value is a standard deviation or stan-
dard error of the mean.

Units of Measurement. Express all measurements in SI (Systcnic Inter-
nationak') units (units and conversion factors listed at Respir Care
1997:42(61:640 and also available at hllpr/Avww.rcjoiinuil.coni/
aiithor_i'iiiiU'/. Show gas pressures (including blood gas tensions) in
millimeters of mercury (mm Hg).

Conflict of Intere.st. On the cover page, authors must disclose any
liaison or financial arrangement they have with a manufacturer or
distributor who.se product is addressed in the manuscript or with the
manufacturer or distributor of a competing product. Such arrange-
ments do not disqualify a paper from consideration and are not dis-
closed to reviewers. Reviewers iire screened for possible contlict of
interest.

Abbreviations and Symbols. Use the standard abhre\ iations and
symbols listed at Respir Care l997:42(6):637-642 (also available
at http://www.rcjoiirnal.coni/aiitlior_guide/). Do not create new
abbreviations. Do not use abbreviations in the title or section head-
inas and do not use unusual abbreviations in the abstract. LIse an

abbrcN iaiion onl\ il llie lei in occurs 4 or more limes in the paper.
Parentheticallv define all abbre\ iaiions: write out the lull term on
first mention, followed by the abbreviation in parentheses.
Example: chronic obstructive pulmonary disease (COPD). There-
after use only the abbreviation. Standard units of measurement and
scientific terms can be abbre\ ialed w ithoul explanation (eg. L/min.
mm Hg. pll. ():).

Please use the lollowing forms; cm If () (not cmll2()l. f (iiol bpm).
f (not 1 1. L/min (not I.PM. l/min. or 1pm). ml. (not ml), mm Hg (not
inmllg). pH (not Ph or Pll). p > 0.0(11 (not p>().()()l ). s (not sec). .Spcj:
(arterial oxygen saturation measured via pulse-oximelry).

Prior and Duplicate Publication. In general, do not submit work that
has been published or accepted elsewhere, though in special
instances the Editor may consider such material if the original pub-
lisher grants permission. Please consult the Editor before submitting
such work.

Authorship. All persons listed as authors must have participated in
the reported work and in the shaping ol the manuscript, all must have
proofread the submitted manuscript, and all should be able to pub-
licly discuss and defend tlie paper's content. A paper of corporate author-
ship must specify the key persons responsible for the article. Attri-
bution of authorship is not based .solely on solicitation of funding,
collection or analysis of data, provision of advice, or similar sen ices.
Persons who provide such ancillai^ services may be recognized in an
Acknowledgments section, but written pennission is required from
the persons acknowledged.

Reviewers: Please supply the names, credentials, affiliations, address-
es, and phone/fax numbers of 3 professionals w hom you consider expert
on the topic of your paper. Your manuscript may be sent to one or
more of them for blind peer review.

Submitting the Manuscript

Submit 3 printed copies and one (3..'>-inch) computer diskette. The
printed copies should each include photocopies of all of the Figures.
Tables, and Appendixes. On the diskette, the manuscript .should be
in one file and the tables in a separate file. If soft copies of the fig-
ures are available, they should also be in a separate file. However, do
not create .^canned versions of figures borrowedfroin other publicatiotis:
clear photocopies are preferable. Include the completed Cover Let-
ter and Checklist (see next page) and permission letters. Mail to Res-
PIR.ATORY C.ARi;. 600 Ninth A\enue. Suite 702. SeaUle WA 98104.
Do not fax manuscripts. Receipt will be acknowledged.

Rkspirat()r\ Care
Editorial Office:

600 Ninth Avenue. Suite 702
Seattle WA 98 104

(206) 223-0558 (voice)

(206) 223-0563 (fax)

rcJDurnulfc'aarc.org

RESPIR,-\T0RY C.AR1-: Manuscript Preparation Guide. Revised 4/01

Cover Letter & Checklist

A copy of this completed form must accompany all manuscripts submitted for publication.

Title of Paper:

Publication Category:

Corresponding Autfior; Pfnone: FAX;.

Mailing Address:

Reprints: QYes □ No E-mail Address:

"We, the undersigned, have all participated in the work reported, proofread the accompanying manuscript, and approve its sub-
mission for publication." Please print and include credentials, title, institution, academic appointments, city and state. If more
than 4 authors, please use another copy of this form.'

'First Author:

Author Signature/Date,

•Second Author:

'Third Author:

Author Signature/Date.

'Fourth Author:

Author Signature/Date,

Has this research been presented in any public forum? □ Yes □ No
If yes, where, when and by whom?

Has this research received any awards? □ Yes □ No
If yes, please describe.

Has this research received any grants or other support, financial or material? □ Yes □ No
If yes, please describe.

Do any of the authors of this manuscript have a financial interest in (or a commercial or consulting relationship to) any of the
products or manufacturers mentioned in this paper or any competing products or manufacturers? □ Yes □ No

■ yes, please describe.

Have you enclosed a copy of the manuscript on diskette?

Is double-spacing used throughout entire manuscript?

Are all pages numbered in upper-right corners?

Are all references, figures, and tables cited in the text?

Has the accuracy of the references been checked, and are they correctly formatted?

Have SI values been provided?

Has all ahthmetic been checked?

Have generic names of drugs been provided?

Have necessary written permissions been provided?

Have authors' names been omitted from text and figure labels?

Have copies of 'in press' references been provided?

□ Has the manuscript been proofread by all the authors?

□ Have the manufacturers and their locations been provided for all devices and equipment used?

RF..SPIRATORY C.^Rh Manu.script Preparation Guide. Revised 4/01

Nc\\s relc;tscs about new producls and services will he eniisiilered Inr [luhhealion in Ihis seclioii.

There is no charge for Ihese hsiings. Send descriptive release and glossy black and while photographs

to RliSHIRATORY Cark. New Products & Services Depl. I !(»() Abies l.ane. Dallas TX 7.'i2:9-45')?.

The Reader Service Card can be found al the back of the Journal.

New Products
& Services

Adhesive Forehead Sensor. The MAX-
FASr^' .Adhesive t-oivheaiJ Sensor is the
fiisi such iiiiun;iiion being introduced
with the Nellcor (hiMax system. Neilcor
says that the Ma.\-Fii.sl adhesive forehead
sensor offers a significant advancement in
patient safety monitoring, detecting
changes in SpOs notably earlier than digit
sensors during poor perfusion conditions.
The MAX-FAST sensor is designed for
use on the patient's forehead, a site closer
to the heart, w hich enables it to respond to
changes in Spo, t\pically one to two min-
utes sooner than digit sensors for patients
with weak pulses. For more information
from Nellcor. circle number 180 on the
reader service card in this issue, or send
your request electronically via "Advertis-
ers Online" at http://www.aarc.org/
buyersguide

Inspiratory Mu.scle Trainer. Creative
Health Products has announced the US
launch of a new product range from
POWERbreathe' . which they describe as
a "revolutionary and versatile inspiratory
muscle trainer." According to Creative
Health Products, the POWERbreathe is
the first training device developed specif-
ically to improve lung function. It is use-
ful for improving breathing for asthmat-

ics and patients with emphysema, bron-
chitis, and cystic fibrosis, claims the man-
ufacturer. Creative Health Products says
the device has an adjuslable valve system
that allows increased inspiratory resis-
tance as the patient's muscles strengthen,
and that the unit is designed to bypass the
resistance section during exhalation. For
more information trom Creative Health
Products, circle number 181 on the reader
service card in this issue, or send your re-
quest electronically via "Advertisers On-
line" at http://www.aarc.org/buyers_
suidc

Personal Patient Monitor. Zoe Medical.
Incorporated has introduced the new
Nightingale PPM. This small, convenient
multi-parameter monitor weighs only 2
pounds and is portable, which makes it
easier to support the more mobile patient,
according to the manufacturer. It comes
with an optional battery and monitors
EKG. SpOi. Respiration, blood pressure,
and temperature. For more information
from Zoe Medical, circle number 182 on
the reader service card in this issue, or
send your request electronically via "Ad-
vertisers Online" at http://www.aarc.org/
buyers_guide/

At-Honie Diagnosis of Sleep Apnea.

Sleep Solutions Inc has intKnluced its
next generation NovaSom QSG"" lor al-
home diagnosis of sleep-disordered
breathing, including obstructive sleep
apnea. According to the manufacturer,
this device is easy to use and has been
cleared by the FDA. They say it is the
first sleep diagnostic device designed
specifically for unassisted, unattended pa-
tient use at home with clinically proven
equivalence to overnight, in -laboratory
polysomnography. When prescribed by a
physician. Sleep Solutions delivers the
device to the patient's home, then re-
trieves the device, downloads the data,
and applies propiietary. automated scor-
ing algorithms to generate a detailed re-
port for the diagnosing physician, accord-
ing to Sleep Solutions. For more informa-
tion from Sleep Solutions, circle number
183 on the reader service card in this
issue, or send your request electronically
via "Advertisers Online" at http://www.
aarc.org/buyers_guide/

RESPIRATORY CARE • JULY 2002 VOL 47 NO 7

845

Notices

Nnijccs 1)1 cuinpL'tJlioiis. M;holarships. Icllowships. cxumiiialum dales, new educatu)nul programs.

and tlic like will be listed here free of charge. Ilems lor the Notices seclion must reach the Journal 60 days

before the desired month of publication (January I for the March issue. February I for the April issue, etc). Include all

pertinent informalion and mail notices to RH.SP1RATOI4Y CarH Notices Depl, 1 1030 Abies Lane. Dallas TX 75229-4593.

^»UKd4. 2002

Withholding and Withdrawing; IJfe Support in

the ICU — GcMclon D Rubcnt'eld MDMSc /
Richard D Branson BA RRT FAARC — Videotape
Available

Weaning from Mechanical Ventilation: New
Insights, New Guidelines — Neil R Madntyre
MD FAARC/ Dean R Hess PhD RRT FAARC —
Videotape Available

Neonatal and Pediatric Ventilators: What's the
Difference? — Mark J Heulitt MD FAARC/
Richard D Branson BA RRT FAARC — Videotape
Available

Ventilator Graphs: What's With That Wave? —

Jon O Nilsestuen PhD RRT FAARC/ Richard D
Branson BA RRT FAARC —Live July 16; Audio
August 13

Helpful LUeb.Sites

American Association for Respiratory Care

http://www.aarc.org

— Current job listings

— American Respiratory Care Foundation
fellowships, grants, & awards

— Clinical Practice Guidelines

National Board for Respiratory Care

h 1 1 p : //\vw w. 11 b re . o rg

RESPIRATORY CARE online

http://www.rcjournal.com

— Subject and Author Indexes

— Contact the editorial staff

— Open FORUM; submit your abstract online

Asthma Management
Model System

http://www.nhlbi.nih.gov

Keys to Professional Excellence

http://www.aarc.org/keys/

Committee on Accreditation for Respiratory Care

http://www.coarc.com

Talking with Patients and Families About
Death and Dying — Helen M Sorensen MA RRT
FAARC/ David J Pierson MD FAARC —Live
August 20; Audio September 17

Pressure vs Volume Ventilation: Does It Matter?

— Robert S Campbell RRT FAARC/ Richard D
Branson BA RRT FAARC — Live September 10/
Audio October 8

Inpatient Management of COPD — Randall
Rosenblatt MD/ David J Pier.son MD FAARC —
Live October 22; Audio November 12

High-Frequency Oscillatory Ventilation —

Thomas E Stewart MD/ Richard D Branson BA
RRT FAARC — Live No\ ember 19; Audio
December 10

The National Board for Respiratory Care —
Examination Fees for 2002

Examination

CRT

Perinatal/Pcdiauic

CPFT

RPFT

Examination Fees

$190 (new applicant)
$150 (reapplicant)

$250 (new applicant)
$220 (reapplicant)

$200 (new applicant)
$170 (reapplicant)

$250 (new applicant)
$220 (reapplicant)

RRT $190 (new) $150 (reapplicant) written only

( Written $200 ( new and reapplicant ) CSE only

& CSE) $390 (new) $.^50 (reapplicant) both

For intormation about other services or fees, write lo the

Nalional Board for Respiratorv Care.

S.'^IO Nieman Road. Lcnexa KS (i6'2l4. or call

( ') 1 .M .s')')-42()(). FAX (9 1 .^ I .s4 1 -0 1 .sd.

or c-niail: nbrc-info{?'nbrc.ori;

846

RL..si'iR,\r()Kt Carh • July 2002 Vol 47 No 7

Nol-for-profit organi/aliims ;ia' ollfa'cl j la-c jilM-'rlisfmi'ill nl up In i-ighl lines In .ipptMr, on a sp;icc;i\\iilahlc

hasis. in Calendar of Evcnis in Rf^SPlRATORI' CAR!-: Ads lor olhor mcclings arc prict-il al S?" Inr nicmlvrs and Shi) lor nonincnihcrs and

require an insertion order- Deadline is the 2l)th of Ihc inonih l«o inonihs preceding Ihe monlh in which you wish Ihc ad lo run

Siihnni copy and insertion orders lo Calendar of Eivents. RKSI'IRAl ORY CARE. 1 1030 Abies Lane. Dallas TX 75229-4593.

Calendar
of Events

Date

AARC & State Society Programs

Contact

July 17-19 TSRC 31st Annual Convention and Exhibition;

San Antonio, TX

TSRC Executive Office (972) 680-2455

July 27

Asthma Information Review course; Flint, Ml

Michigan Society for Respiratory Care.
(734) 677-6772, www.michiganrc.com

Aug. 1-3 OSRC's Contemporary Concepts in Respiratory Care;

Indepentdence, OH

Tom Kallstrom at tom.l<allstrom@fairvlewhospltal.org;
or Jeffrey Davis at davisj@ccf.org

Aug. 1-4 Georgia Society for Respiratory Care's Summer Meeting;

St. Simons, GA

David Ellwanger, (770) 991-8558,
ellwanger_david@promina.org

Aug. 14-16 31st TnState Respiratory Care Conference; Biloxi, MS

Linda Berry (205) 343-8475; www.tsrcc.org

Sept. 5-6 Vermont/New Hampshire Society for Respiratory Care

Annual Meeting; Killington, VT

Xan Gallup (800) 333-8095, ext. 360 or
xgallup@merriam-graves.com

Sept. 5-7 TSRC North Region - Pineywoods District 1 6th Annual Fall

Seminar; Lufkin, TX

Ram Mollis (409) 639-7006

Sept. 11-12 MSRC 25th Annual State Conference; Sturbridge, MA

Sept. 12-13 PSRC Southwest District's 29th Annual Seminar in
Pulmonary and Sleep Medicine; Pittsburgh, PA

Gail Varcelotti (724) 941 -8792,
SWDisthct@psrc.net

Sept. 12-13 Alabama Society for Respiratory Care Annual Meeting;
Birmingham, AL

Bill Pruitt (251) 434-3405 or
wpruitt@jaguar1 .usouthal.edu

Sept. 19-

•20

Kansas Respiratory Care Society Western Kansas
Conference; Hays, KS

www.krcs.org or e-mail Julia Downs
at jddrrt@yahoo.com

Oct.5-8

AARC 48th International Respiratory Congress; Tampa, FL

AARC, (972) 243-2272, www.aarc.org

Date

Other Meetings

Contact

Sept. 13-14

Practical Spirometry Certification Course; Chicago, IL

Mayo Pulmonary Services Education Office,
(800)533-1653

Oct. 31 - Nov. 1 Practical Spirometry Certification Course; Rochester, MN

Mayo Pulmonary Services Education Office,
(800)533-1653

Respiratory Care . July 2002 vol 47 No 7

847

Authors

in This Issue

Blair. Jim 829

Clouiier. Michelle M 833

Colby. Conrad 833

Da\ idson. Kalhryn L 823

l-iiik, James B 75^. 769. 786. 797

Graham. Mark G 834

Hess. Dean R 757

Lapin. Craig D 778

Lew IS. Robert M 808

Mahlmeister, Michael J 797

Malhewson, Hugh S 830

Rubin. Bruce K^ 759. 761, 818

Sobush. Dennis C 829

Weaver. Lindell K 831

Advertisers
in This Issue

T(t advertise in RKSIMKA H)H\ C \RI-:, contact Tim Goldshun. Director. Ad\t'rtising Sales, e-mail: goldsbun (?' aarc.org for rates
and media information. Contact Karen Camlet. Advertising Representative, e-mail: camlet <" aarc.org. for recruitment/classified
advertising. Saks olTice: J8I» Tcqui'sta Drive. Tequesta. FL .VM69. Telephone: 551-745-6793, Kax: 551-745-5795.

Send production materlials for AARC publications to Binklev @aarc.org or AARC. 11030 Abies Lane. Dallas TX 75229^593
c/o Beth Binklev

Circle # Company

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Memorial Hospital of South Bend 836

SEE AD

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Monaghan

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800-833-9653

117

Nephron Phannaceulicals Corp

800-443-4313

407-999-0133

113

Praxair

744

800-299-7977

121

Pulnionclic Systems

751

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IIX

Respironics

800-962-1266

112

Siemens

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Washoe Health Svsteni

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775-982-6387

123

Whidbey General Hospital

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360-678-7656

www .thc\ est.com
wwu.daleiiied.com
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www.pulmoneticsystenis.com
www.respironics.coni
www. servo-i.com
www.washoeheallh.coni
www.whidbeygen.org

{'()l•^Kl(;HT Information. Rhsi'ikaiorv Cake is copyrighted hy

IXicdalus Enterprises Inc. Repriidiiclioii in u hole or In part without the express
written pemiission ot Daedalus Enterprises Inc is prohihited. Pemiission to
photocopy a single iulicle in this Journal lor noncommercial purposes of scien-
tific or educational advancement is granted. Pennission for multiple photo-
copies and copies for commercial purposes must be requested in writing, via e-
mail lb;ircusCn'aarc.org). or telephone (972-243-2272). and approved by RBS-
I'lRATOR'i' Care. Anyone may. without permission, quote up to .^(K) words
of material in this journal provided the quotation is for noncommercial use and
RESPIRATOR'!' C.-\RI-: is credited. Longer quotation requires w ritten approval
by the author and publisher. Single reprints are available only from the au-
thors. Reprints for commercial use may be purchased from Daedalus Enter-
prises Inc. For more infomiation and prices call 972-243-2272.

Disclaimer. The opinions expressed in any article or editorial are those
of the author and do not necessarily reflect the views of the Editors, the
American Association for Respiratory Care (AARC). or Daedalus Enter-
prises Inc. Neither are the Editors, the AARC. or the Publisher responsible
for the consequences of the clinical applications or use of any methods or de-
vices described in any article or advertisement.

SUBSCRIFITON RaTK.S. Domestic individual subscription rales are
$89.9.'i per year (12 issues) and $174.90 for 2 years in the US and Puerto
Rico. Foreign individual rates are $109 per year and $208 for 2 years in all
other countries (add $94 per year for air mail). Domestic institutional rates

are $1 I9.y,s for one year and $229.90 for two years. Foreign institutional
rates are $130 for one year and $2.s.'v for two years. Single copies when
available cost $10; add $9 for air mail postage to oveiseas countries.
Checks should be made payable to RESPIRATOR'*' CARE and sent to the
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call 972-24.V2272.

SLB.SCRIPTION RaTF:S for Associations. Basic annual subscrip-
tions are ottered to members of asscxiations according to their memhership en-
rollment: 1 0 1 -.St X) niembeiN = $ 1 6.2.Vyear ( each i; .SO 1 - 1 ..SO) = $ 1 5.7.Vyear (each );
1 .5(X)- 1 ().(XK) = $ 14.7.'i/ye;ir (each); more than I O.(XX) = $13.75/year'(each). For
infomiation. contact Ray Masferrer at 972-243-2272.

CR-\N<;k of ADDRFXS. Notify the AARC at 972-243-2272 as soon as
possible of any change in address. Note the subscription number (from the
mailing label) and your name, old address, and new address. Allow 6
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MaNIISCRIPTS. The Journal publishes clinical studies, method/device
evaluations, reviews, and other materials related to cardiopulmonary med-
icine and research. Manuscripts may be submitted to the Editorial Office. Res-
piratory Care. 600 Ninth Avenue. Suite 702. Seattle WA 9X104. Tele-
phone 206-223-0558. Instructions for authors are printed in every issue.

848

Respiratory Care • July 2002 Vol 47 No 7

...An Ansvs^er to Cross Contamination!

'Respiratory Care
Subscription Form

I.S. SubscriptioiK

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Information

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■ ^ ktinK.r.*! Cv« luHtti^Kfl infCTTnWion. t

^■Bie 103 104 109

106

107 108 109 110

111

112

113

114

115 116 117 118

ii'i i:ii i:i Ml \2i

i:4

1:5 126 127 128

129

I'n

i<;

1 tt 1 t4 M^ 1 <n

Bt. 138 139 140 141

142

143 144 145 146

147

148

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151 IS2 I^IM:

155

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165

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WKam^iii i7b 177

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179 180 181 182

183

184

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186

187 188 M IW

191 192 193 194 195

197 198 199 2(X)

IVxnKleKxnoKlluii

„™

Name

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Additss

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July 2002 Enpirw 10/15/02

RE/PIRATORy CARE

T^TEOFINS
OR PRACTICE

1 O Hospital

2 □ Skilled Nursing Facility

3 D Subacute Care Facility

4 D Home Care Practice

5 n School

6 □ Distributor

11 DEPARTMENT

A D Respiratory Care
B D Cardiopulmonary
C D Subacute Care
D D Home Care

m SPECIALTY

1 D Clinician

2 D Perinatal/ Pediatrics

3 D Critical Care

4 n Research

5 D Subacute Care

6 n Diagnostics/

lonary Function

7 D Management

8 D Home Care

9 a Rehabilitation

10 D Education

IV POSITION

A n Department Head
B a Chief Therapi.st
C n Supervisor
D n Staff Therapist/

Technician
E G Medical Director
F D Educator/lnstnjctor
G n Sales
H G Other (pleaK&pecify)

V y^RE YOU AN AARC MEM-
BER?

I D Yes 2 a No

hrine

ISP 2.25%

-99

'rapped
Sulfite Free
Ise Vials

43 I 3

in This Issue

Blair, Jim 829

Cloulier, Michelle M 833

Colby. Conrad 833

Davidson. K.ithn n 1 823

Fink. James B lf,9. 769. 786. 797

Graham, Mark G 834

Hess. Dean R 757

Lapin. Craig D 778

Lewis. Robert M 808

Mahlmeistcr. Michael J 797

Mathewson. Hugh S 830

Rubin. Bruce K 759, 761. 818

.Sobush. Dennis C 829

Weaver, l.indell K 831

Adverti

I'his 1;

Circle # Conipan

122

Ad\ance

115

Dale Mei

116

DHDHe

119

Hans Ru.

120

J H Emei

124

Memoria

114

Monas;h;

117

Nephron

113

Praxair

121

Pulmone

118

Respiron

112

Siemens

125

Washoe 1

123

Whidbey

BUSINESS REPLY MAIL

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848

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