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July 2001Volume 3, Number 7
Author
Charles Stewart, MD, FACEP
Colorado Springs, CO.
Peer Reviewers
Michael S. Radeos, MD, MPH
Clinical Assistant Professor of Emergency
Medicine in Medicine, Weill Medical College
of Cornell University, Lincoln Medical and
Mental Health Center, Bronx, NY.
David Della-Giustina, MD
Program Director, MadiganUniversity ofWashington Emergency Medicine Residency,
Tacoma, WA.
CME Objectives
Upon completing this article, you should be able to:
1. discuss the advantages of both endotracheal
intubation and noninvasive ventilation;
2. describe the techniques and indications for
both CPAP and BiPAP;
3. summarize the current evidence relating to
the use of noninvasive ventilation for
COPD, pulmonary edema, asthma, and
other conditions; and
4. list the contraindications and potentialcomplications of noninvasive ventilation.
Date of original release: July 2, 2001.
Date of most recent review: June 29, 2001.
See Physician CME Information on back page.
EMERGENCYMEDICINEPRACTICEAN EVIDENCE-BASED A PPROACH T O EMERGENCY MEDI CINE
Editor-in-Chief
Stephen A. Colucciello, MD, FACEP,Assistant Chair, Director ofClinical Services, Department ofEmergency Medicine, CarolinasMedical Center, Charlotte, NC;
Associate Clinical Professor,Department of EmergencyMedicine, University of NorthCarolina at Chapel Hill, ChapelHill, NC.
Associate Editor
Andy J agoda, MD, FACEP, Professorof Emergency Medicine; Director,International Studies Program,Mount Sinai School of Medicine,New York, NY.
Editorial Board
Judith C. Brillman, MD,ResidencyDirector, Associate Professor,Department of Emergency
Medicine, The University ofNew Mexico Health SciencesCenter School of Medicine,Albuquerque, NM.
W. Richard Bukata, MD,AssistantClinical Professor, EmergencyMedicine, Los Angeles County/
USC Medical Center, Los Angeles,CA; Medical Director, EmergencyDepartment, San Gabriel ValleyMedical Center, San Gabriel, CA.
Francis M. Fesmire, MD, FACEP,Director, Chest PainStrokeCenter, Erlanger Medical Center;Assistant Professor of Medicine,UT College of Medicine,Chattanooga, TN.
Valerio Gai, MD,Professor and Chair,Department of EmergencyMedicine, University of Turin, Italy.
Michael J . Gerardi, MD, FACEP,Clinical Assistant Professor,Medicine, University of Medicineand Dentistry of New Jersey;Director, Pediatric EmergencyMedicine, Childrens Medical
Center, Atlantic Health System;Vice-Chairman, Department ofEmergency Medicine, MorristownMemorial Hospital.
Michael A. Gibbs, MD, FACEP,Residency Program Director;Medical Director, MedCenter Air,
Department of EmergencyMedicine, Carolinas MedicalCenter; Associate Professor ofEmergency Medicine, Universityof North Carolina at Chapel Hill,Chapel Hill, NC.
Gregory L. Henry, MD, FACEP,CEO, Medical Practice RiskAssessment, Inc., Ann Arbor,MI; Clinical Professor, Departmentof Emergency Medicine, Universityof Michigan Medical School, AnnArbor, MI;President, AmericanPhysicians Assurance Society, Ltd.,Bridgetown, Barbados, West Indies;Past President, ACEP.
Jerome R. Hoffman, MA, MD, FACEP,Professor of Medicine/Emergency Medicine, UCLA
School of Medicine; AttendingPhysician, UCLA EmergencyMedicine Center; Co-Director,The Doctoring Program,UCLA School of Medicine,Los Angeles, CA.
John A. Marx, MD,Chair and Chief,
Department of EmergencyMedicine, Carolinas MedicalCenter, Charlotte, NC; ClinicalProfessor, Department ofEmergency Medicine, Universityof North Carolina at Chapel Hill,Chapel Hill, NC.
Michael S. Radeos, MD, MPH, FACEP,Attending Physician inEmergency Medicine, LincolnHospital, Bronx, NY; ResearchFellow in Emergency Medicine,Massachusetts General Hospital,Boston, MA; Research Fellow inRespiratory Epidemiology,Channing Lab, Boston, MA.
Steven G. Rothrock, MD, FACEP,FAAP,Associate Professorof Emergency Medicine,
University of Florida; OrlandoRegional Medical Center; MedicalDirector of Orange CountyEmergency Medical Service,Orlando, FL.
Alfred Sacchetti , MD, FACEP,Research Director, Our Lady of
Lourdes Medical Center, Camden,NJ; Assistant Clinical Professorof Emergency Medicine,Thomas Jefferson University,Philadelphia, PA.
Corey M. Slovis, MD, FACP, FACEP,Department of EmergencyMedicine, Vanderbilt UniversityHospital, Nashville, TN.
Mark Smith, MD,Chairman,Department of EmergencyMedicine, Washington HospitalCenter, Washington, DC.
Thomas E. Terndrup, MD,Professorand Chair, Department ofEmergency Medicine, Universityof Alabama at Birmingham,Birmingham, AL.
Noninvasive Airway
Management Techniques:How And When To Use ThemThe old fellow is looking grim. Hes sweating profusely, and his lips are blue. Hes
been here beforethree episodes of CHF in the past year.
The nitro drip is running, but the blood pressure is marginal. He isnt
responding to the furosemide. As you call for the airway cart, he suddenly becomes
more alert. The old man grabs your arm and in a strained but unmistakable voice,
gasps, Nono tube.
PATIENTS in respiratory distress are among the most frustrating,
frightening, and challenging patients seen by the emergency physician.
They arrive with a state of severe anxiety, intense physical effort, and may
wear out as the clinician attempts to get a history. Indeed, among the
most common ED complaints are SOB (short of breath) and not getting
enough airboth of which can stem from myriad causes, such as asthma,
chronic obstructive pulmonary disease (COPD), and pulmonary edema.
Noninvasive ventilation (NIV) is the technique of augmenting respira-
tions without a tracheostomy or endotracheal intubation. The application of
this technique to emergency and critical care patients received much
attention during the 1980s and 1990s. It is the subject of numerous commen-
taries, review articles, editorials, physiologic investigations, case studies,
and randomized, controlled clinical trials.1 But what is its role in the day-to-
day practice of emergency medicine? What is the evidence?This issue ofEmergency Medicine Practice explores this controversial and
evolving topic. (It also complements two prior issues ofEmergency Medicine
Practice: Emergency Endotracheal Intubations: An Update On The Latest
Techniques, published in May 2000, and Dyspnea: Fear, Loathing, And
Physiology, published in August 1999.)
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History And Technology
Three modes of NIVcontinuous positive airway
pressure support, bi-level airway pressure support (also
called pressure support ventilation), and external
negative pressure ventilation (the iron lung)are well-
described in the literature. Current equipment uses the
positive pressure technique, in which respirations are
aided through the use of increased airway pressure.
The use of positive airway pressure was firstreported in the 1930s, when facemasks powered by
vacuum cleaners were used to treat pulmonary edema.2 A
few years later, World War II aviators used pressure
masks to supply oxygen at high altitudes. These early
technologies evolved into todays mechanical ventilators.
The endotracheal tube came into routine use during the
early 1960s.
Advances in the late 1970s and early 1980s brought
two methods of noninvasive positive pressure ventila-
tion. Continuous positive airway pressure (CPAP) ventilation
improved oxygen exchange in patients with hypoxemia
and acute respiratory failure.
Intermittent positive pressure ventilation (IPPV) was
introduced as an inspiration-triggered, momentary boost
of positive airway pressure. It was initially used to rest
the respiratory muscles in patients with respiratory
fatigue. Twenty years ago, intermittent positive pressure
breathing (IPPB) was used in asthmatic patients to reduce
the work of breathing, deposit aerosolized agents deep
into the respiratory tree, and improve drainage. Most of
these claims have since been repudiated, and IPPB is no
longer routine in the treatment of asthma.
Bi-level positive airway pressure (BiPAP) devices also
give positive airway pressure throughout the respiratory
cycle. They use a higher inhalation pressure (IPAP) and a
lower pressure during exhalation (EPAP).3 When the
spontaneous mode of a BiPAP machine is used, it
functions as a flow-triggered pressure support ventilator.
(BiPAP is actually a trade name for a machine pro-
duced by Respironics.)
In the past, external negative pressure ventilation
(the iron lung) was used to manage acute and chronic
respiratory failure. These negative pressure or tank
ventilators of the 1950s were a form of NIV that did not
require a spontaneously breathing patient. Modern
literature is essentially devoid of articles on external
negative pressure ventilation, and few hospitals have this
equipment available.4
State Of The Literature
Multiple authors have studied NIV in patients in acute
respiratory failure.5-12 Most compare NIV with intubation
and use subsequent intubation as evidence of failure of NIV.
While intubation is unavoidable in some patients, most
studies show that NIV can prevent the need for mechanical
ventilation in appropriately selected patients. Only one
study concluded that NIV would delay intubation and
subsequently result in increased mortality.13
Much of the literature on NIV suffers from the
usual pitfalls, such as lack of randomization, lack of
blinding, or differences between the groups. Some
Abbreviations Associated With Noninvasive VentilationAC: Assist control mode of respiration. The patient
triggers ventilation when he or she inspires.
(The ventilator should have a backup mode
to ensure that a set number of breaths per
minute are taken.)
ACPE: Acute cardiogenic pulmonary edema.
ARF: Acute respiratory failure.
BiPAP: Bi-level positive airway pressure. BiPAP is pressure
support ventilation with expiratory positive airway
pressure. (Also, the trade name for the machine.)
CHF: Congestive heart failure.
CMV: Continuous mandatory ventilationthe most basic
of ventilation assistance. There is no provision for
patient-assisted breaths or spontaneous breaths. All
paralyzed patients will be on CMV.
CPAP: Continuous positive airway pressure.
EPAP: Expiratory positive airway pressure.
IMV: Intermittent mandatory ventilationthe ventilator
allows patients to breathe independently of the
ventilator, with a set minimum respiratory rate.
IPAP: Inspiratory positive airway pressure.
NIV: Noninvasive mechanical ventilation.
PEEP: Positive end expiratory pressure. PEEP is provided by
valves on the exhalation limb of the ventilators circuit
and is set by the therapist.
PEFR: Peak expiratory flow rate.
PSV: Pressure support ventilation. BiPAP is a subset of
pressure support ventilation with EPAP applied.
SIMV: Synchronized intermittent mandatory
ventilation. The ventilator has both a set rate
and assists with ventilatory efforts if the patient
does not breathe spontaneously. Replaces IMV in
most modern ventilators.
Vt: Tidal volume.
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studies are less than clear regarding inclusion and
exclusion criteria. When evaluating studies of NIV vs.
endotracheal intubation, one must be aware that any
true comparison suffers from an unavoidable selection
bias. In order to be randomized to NIV, the patient
must be awake and cooperative. Once randomized to
NIV, a patient who deteriorates must immediately be
treated with endotracheal intubation. The best studies
strictly define criteria for subsequent intubation prior to
patient enrollment.
The best evidence regarding the use of NIV in
the acutely ill patient involves the treatment of COPD,
and this fact is reflected in recent clinical guidelines.
A joint panel from the American College of Physi-
ciansAmerican Society of Internal Medicine (ACP-
ASIM) and the American College of Chest Physicians
(ACCP) recently published a position paper on the
management of acute exacerbations of COPD.14 On the
basis of five randomized, controlled trials and f ive
observational studies, the authors concluded that
noninvasive positive pressure ventilation [NPPV] is a
beneficial support strategy that decreases risk forinvasive mechanical ventilation and possibly improves
survival in selected hospitalized patients with respira-
tory failure.
Physiology And Noninvasive Ventilation
Respiratory failure can result from either hypoxia or
hypercapnia, both of which are amenable to NIV. NIV
improves lung mechanics by recruiting atelectatic alveoli,
improving pulmonary compliance, and reducing the
work of breathing. Increasing mean airway pressure
forces oxygen across the alveolar membrane in patients
with underlying pulmonary disease.15
In addition,positive airway pressure reduces venous return to the
heart. In most patients, this decrease in preload is
inconsequential. In one study of 19 patients with COPD
and acute ventilatory failure, the authors found no
significant changes in pulmonary artery pressures and
cardiac output by Doppler echocardiography in 15
patients; four patients (21%) showed a significant
reduction (> 15%) of cardiac output during NIV.16
NIV, however, can cause a variety of negative
physiologic effects. Some patients may strain against the
ventilator and increase the work of breathing. Increased
intrathoracic pressure can decrease venous return and
thus cardiac output in those with marginal cardiacfunction.17 In some patients, the increased airway
pressure may cause overdistension of the alveoli and
produce barotrauma in acutely injured lungs.18
Management Of Respiratory Failure
IntubationThe Gold StandardEndotracheal intubation and subsequent mechanical
ventilation are lifesaving therapies in many cases of
respiratory failure. Indeed, endotracheal intubation is the
traditional gold standard for the management of acute
respiratory failure of any etiology. A deviation from this
standard must offer either fewer risks or greater benefits
to the patient and should be based on strong evidence.
The data show that in appropriately selected patients, NIV
may improve survival, increase patient comfort, and
decrease the cost of hospitalization.
Problems With Intubation
Despite the well-established position as the gold stan-
dard in respiratory failure, there are definite non-trivial
risks associated with endotracheal intubation.
Misplacement of the tube may have lethal conse-
quences, including trauma to the airway, esophageal
intubation, and aspiration. Other hazards during the
intubation attempt include failure to intubate, hypoxia,
bronchoconstriction, and increased intracranial pressure.
A variety of infections result from intubation. Four to
eight percent of patients will experience clinically
significant aspiration during the act of intubation.19
Subsequent ventilator-associated pneumonias are
frequent and may occur in 20%-25% of all patients
intubated for more than 48 hours.20,21 Sinusitis is a
delayed complication of nasal intubation.22
In addition to infectious complications, placing a
patient on a ventilator may ultimately weaken the
respiratory muscles.23 This is a significant factor during
the weaning process in a patient with respiratory disease.
Intubation is also uncomfortable. Agitation is so
common that sedation must be routine. Finally, even if
the patient is awake, he or she is unable to eat, drink, or
speak with a tube through the vocal cords.
Advantages Of Noninvasive Ventilation
NIV may have significant advantages over endotrachealintubation. First, it is significantly less expensive than
mechanical ventilation, and hospital stays may be
shorter. Patients require less sedation, experience less
muscle weakness, and have fewer complications,
including infections.
Technique Of NoninvasiveMechanical Ventilation
EquipmentNIV may be provided by a machine designed specifically
for this task, or by a traditional, full-capacity ventilator
capable of the appropriate settings. The respiratory ratemay either vary with patient demand or remain fixed at a
set rate. Similar flexibility is available for the delivery
mode that can give the patient either a desired volume or
pressure. Both pressure- and volume-limited modes have
been used successfully for NIV.
Volume-Limited VentilationIf volume-based NIV is used, the ventilator delivers a set
flow to the patient for a timed interval. Unfortunately, if
there is a leak at the patients mask or along the tubing,
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the patient will not receive the specified volume. Leaks in
a mask secured with straps can develop quickly, espe-
cially in the restless patient. For this reason, some
authorities recommend that volume-based NIV not be
used for acutely ill patients (or, at least, it should be used
with extreme caution).1 The actual data on this are mixed.
A recent study showed that respiratory comfort (assessed
by visual analog scale) was greater in patients who
received pressure support ventilation compared to the
volume mode.24 However, the work of breathing was
diminished to a greater extent in the volume mode.
Continuous Positive Airway PressureCPAP delivers a static airway pressure maintained
throughout both the inspiratory and expiratory cycle.
CPAP is functionally equivalent to positive end expira-
tory pressure (PEEP) used in the intubated patient. To
compensate for leaks, CPAP devices regulate airflow to
maintain a set pressure. The amount of positive airway
pressure can be adjusted to meet clinical needs. Gener-
ally, 5-10 cmH2O is the most common, and pressures
above 15 cmH2O are rarely needed (or tolerated).25
(SeealsoTable 1.)
Bi-level Positive Airway PressureBiPAP delivers continuous positive airway pressure
coupled with inspiratory pressure support. The machine
allows a different level of inspiratory and expiratory
pressure support. Theory holds that positive expiratory
pressure is functionally equivalent to CPAP, while the
positive inspiratory pressure will further decrease the
work of breathing. These two levels are clinically
matched to patient demands.
The BiPAP machine cycles between a targeted
peak inspiratory pressure (inspiratory peak airwaypressure [IPAP]) and a lower end expiratory pressure
(expiratory peak airway pressure [EPAP]). The latter may
also be called the peak end expiratory pressure. (The
abbreviation may be confused with positive end expira-
tory pressure.) The ventilation achieved will vary with
patient effort and with the compliance of the lungs. The
BiPAP machine, however, can easily be programmed by
the respiratory therapist to deliver CPAP instead of bi-
level pressure.
Pressure support is an important concept. The level of
pressure support in BiPAP is equivalent to the difference
between the inspiratory and expiratory pressures (that is,
IPAP minus EPAP equals pressure support).
The cycle may be fixed in the machine as a function
of time, or the machine may have an algorithm that
terminates the cycle when inspiratory flow declines to a
preset level. If the inspiratory phase is too prolonged,
then the patient must actually work against the mechani-
cal inspiration in order to exhale. This markedly increases
the patient discomfort and, more importantly, the
patients work of breathing.
The ventilator must be properly adjusted so that the
peak flow and the patients demand are synchronized. If
the patient is both dyspneic and strong, then the ventila-
tor must generate enough flow to meet the inspiratory
pressure. If the ventilator cannot provide an adequate
flow, then the patient will work harder by trying to suck
air from the machine. Conversely, if the ventilator
exceeds demand, then the patient will be uncomfortable,
and gastric distention may result.Supplemental oxygen can be supplied through the
tubing or may be added directly to the mask. Because the
supplemental oxygen will be diluted by the high flow
through the system, high concentrations of oxygen may
be needed.
Proportional Assist VentilationProportional assist ventilation is a new NIV technique in
which the ventilator generates pressure in proportion to
the patients effort. The applied pressure is designed to
overcome the elastic and resistance loads in proportion to
the patients volume and flow of breathing. This tech-
nique has been described in seven patients with an acuteexacerbation of COPD.9 Although the initial report
appears promising, more research is needed before any
recommendation can be made.
Patient Selection
An alert and cooperative patient is critical for initiating
NIV. (See alsoTable 2.) Patients who have CO2 narcosis
Table 1. Advantages And Disadvantages Of CPAP.
Advantages Improves pulmonary function
Improves gas exchange Reduces inspiratory threshold pressure Reduces venous return to the heart Increases functional residual capacity May increase or decrease cardiac output depending on
underlying pathology
Disadvantages Reduces venous return to the left ventricle (this may also
be an advantage)
Potential for aspiration if patient vomits
Table 2. Indications For Noninvasive Ventilation.
NIV is considered highly effective in treatment of: Acute exacerbation of COPD
Obstructive sleep apnea
NIV may be effective for:
Cardiogenic pulmonary edema without shock (CPAP,not BiPAP)
Respiratory failure in patients with cystic fibrosis orneutropenia and fever
Asthma Pneumonia Near-drowningThe patient who is not a candidate for intubation
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from COPD may be an exception to this requirement. A
significant number of these patients will improve
mentation within 30 minutes during NIV, resulting in
fewer intubations.26
NIV should be avoided in patients who cannot
handle their secretions, who have life-threatening
refractory hypoxemia (PaO2 < 60 mmHg on 100%
inspired oxygen), or who are hypotensive.1,26 These
patients are more appropriately managed with intubation
and mechanical ventilation.
Initiating Pressure SupportIf NIV is to be successful, a management approach that
emphasizes the earlier, the better may be helpful. One
small study suggested that when NIV is available within
minutes, some patients with severe new-onset respiratory
distress may be spared intubation.27 Other studies
confirm this finding.7 Keeping the CPAP or BiPAP
machine in the ED permits such early intervention.
Although NIV is generally well-tolerated, patients
will often require coaching when starting therapy.
The respiratory therapist should hold the mask to thepatients face in the initial phase to allow the patient
to become familiar with the mask and the high airflow.
Providing reassurance and adequate explanations to
the patient is critical. Patients should be instructed to
call the nurse if they need to remove the mask to
expectorate, if they develop abdominal distention,
or if they become nauseated.
Mask Selection: Nasal Mask Or Facemask?The choice in an ED is usually between a full facemask
and a nasal mask. Both devices are effective, and the ED
should have several types of masks available.
A comfortable and properly fitted mask is important.Although a tight fit will decrease leakage from the mask,
it may be too uncomfortable for the patient. Small
degrees of air leakage are acceptable as long as the tidal
volume is greater than 7 mL/kg.28 A proper fit may be
quite difficult in edentulous patients and those with a
beard or substantial mustache. Nasal pads may be more
appropriate for these patients. In certain individuals,
tincture of benzoin applied to the facial skin provides a
better mask-face seal.
FacemaskAlthough the evidence is not conclusive, some believe
that facemasks are probably more effective than nasalmasks in the acutely ill. Because most dyspneic patients
are mouth breathers, masks that cover the mouth may
result in less air leakage than nasal masks.28
Nasal MaskMost studies have used a nasal mask. However, if the
mask covers the nostrils only, the airway is depressurized
when the patient opens his or her mouth. Nonetheless,
nasal masks offer many advantages. Eating, drinking,
and talking are relatively easy. The nasal mask adds less
dead space, causes less claustrophobia, and minimizes
aspiration if vomiting occurs.
Nasal PadsA variant of the nasal mask is nasal pads or plugs. This
device fits within the patients nostrils and delivers gas
directly into the nose. The nasal pads decrease skin
irritation across the bridge of the nose, at the expense of
irritation within the nostrils.
SedationDuring NIV, the patient rarely requires sedation; indeed,
it interferes with patient cooperation. Extremely anxious
patients are unsuitable candidates for NIV and may
require endotracheal intubation and sedation. If neces-
sary, moderately anxious patients may be given a small
amount of morphine sulfate or a benzodiazepine. The
clinician should carefully assess each patient to ensure
that agitation is psychological and not due to worsening
hypoxia, hypercarbia, hypovolemia, or hypotension.
Machine SettingsCPAP SettingsIf CPAP is used, start with low pressures (5 cmH 2O) and
increase in increments of 2 cmH2O as tolerated by the
patient. Respiratory goals may include an exhaled tidal
volume greater than 7 mL/kg, a respiratory rate of less
than 25, oxygen saturation greater than 90%, and perhaps
most important, patient comfort.28
BiPAP SettingsWith BiPAP, the IPAP setting may range from 4-24
cmH2O, while the EPAP setting may vary from 2-20
cmH2O. Typical initial settings for BiPAP are levels of8-10 cmH2O IPAP and 2-4 cmH2O EPAP. These settings
presume that the lower pressures will allow patient
tolerance and training. When using BiPAP, remember
that the inspiratory pressure must be maintained
higher than the expiratory pressure at all times to
ensure bi-level flow. Flow must be synchronized with
patient respiratory efforts.
Pressure Support Ventilation SettingsTypical initial pressure support ventilation would be 8-10
cmH2O combined with PEEP of 2-4 cmH2O. (This is
equivalent to BiPAP with IPAP at 8-10 cmH2O and EPAP
at 2-4 cmH2O.)
Indications For NoninvasiveMechanical Ventilation
The most compelling symptom is the inability to breathe.
Prehospital Use Of NIVThere are few data on the prehospital use of NIV. In one
non-randomized study, patients presumed to have
congestive heart failure (CHF) were given BiPAP by the
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medics during transport and were compared to matched
controls treated without NIV.29 In this trial, 97% of EMTs
who used BiPAP thought it improved patients dyspnea;
however, data analysis showed no statistical difference
between groups in the length of subsequent hospital stay,
intubation, or mortality. Likewise, a European study
involving a mobile intensive care unit also showed that
aggressive therapy of CHF in the prehospital arena
improved symptoms during transport but had no effect
on long-term mortality.30
Chronic Obstructive Pulmonary DiseaseAcute respiratory failure in COPD is associated with
significant expiratory obstruction, dynamic hyperinfla-
tion, and respiratory muscle fatigue. The end result is
hypercapnia followed by respiratory acidosis. NIV can
improve this situation.31
Standard medical therapy for COPD consists of
inhaled -agonists, anticholinergic agents, systemic
steroids, and antibiotics.32,33 When these agents fail,
intubation and ventilation for 24-72 hours allow the
respiratory muscles to rest with subsequent improvementin ventilation. Usually the decision to intubate is made
within the first 24 hours of hospitalization, often during
ED therapy.34
There have been at least four randomized, controlled
trials comparing NIV to conventional therapy in patients
with COPD.12,26,35,36 Most of the data show that NIV results
in fewer intubations compared to standard therapy.
The studies that compare NIV with standard medical
therapy in COPD, both randomized and non-random-
ized, have examined a variety of endpoints. Two studies
show that NIV decreased hospital stays, while a third
was too small to show any difference in this param-
eter.26,35,37 These same studies showed a clear decrease inmortality of the patients treated with NIV. A fourth trial,
by Barbe et al, did not demonstrate an advantage in NIV
in patients with mild exacerbations of COPD; however,
this trial was performed in a non-acute setting, and no
patients required intubation.36
There have been several important meta-analyses
regarding the use of NIV in COPD.38,39 They show that NIV
is of value in treating acute exacerbations of COPD. Study
patients have decreased hospital mortality, intubation rates,
and length of stay. Furthermore, one economic evaluation
noted a cost savings of $3244 for each patient treated with
NIV vs. mechanical ventilation.40
Importance Of Early InterventionIn the COPD patient, NIV should be applied as soon as
indicated to achieve maximum benefit. In one study, the
success rate was 93% when NIV was used early in the
course of hospital treatment, while the success rate was
only 63% when standard medical therapy was used
before NIV.7
Early initiation of NIV not only may help in the
acute phase of treatment, but it also may improve long-
term prognosis. In one study, the noninvasively treated
patients with COPD had a lower 12-month mortality rate
than matched historical controls who had been intubated
(39% vs 50%).41
Pulmonary EdemaMost patients with pulmonary edema can be stabilized in
the ED with conventional pharmacologic therapy and
supplemental oxygen. However, a small number of
patients will present with severe, persistent hypoxemia
and respiratory failure that requires assisted ventilation.
Multiple clinical trials and case studies conducted
over the past 20 years support a role for NIV in the
management of pulmonary edema.6,13,42-46 In one retro-
spective series of emergency patients presenting with
acute CHF, use of NIV avoided endotracheal intubation
in 91% of the patients in whom it was applied.47 To date,
at least four randomized studies have compared CPAP
with conventional intubation and pharmacologic therapy
in the treatment of patients with pulmonary edema.15,48-50
In the first trial, 40 patients were randomized to a
CPAP group or ambient pressure breathing.48 The CPAP
group showed a more rapid improvement in oxygen-ation, a fall in PaCO2, and a better respiratory rate, heart
rate, and blood pressure than the ambient pressure
group. Six of the CPAP group required intubation
compared to 12 in the ambient pressure group.48
In the second trial, 39 patients were randomized to
a CPAP or ambient pressure.15 The CPAP group
demonstrated similar improvement in monitored
respiratory functions and vital signs. However, no
patients in the CPAP group required intubation,
whereas 35% of patients in the ambient pressure group
needed intubation.
In the third study, 100 ICU patients were randomized
to ambient pressure or CPAP.49 Based on physiologicparameters, the CPAP group did better, demonstrating
lower intrapulmonary shunt fraction and alveolar-arterial
oxygen gradients as well as increased stroke volume and
PaO2. There was also a statistically significant difference
in the number of patients who required intubationeight
patients in the CPAP group compared to 18 among the
controls. The study size was not large enough to demon-
strate a decrease in mortality.
In the most recent study, 40 patients were randomly
assigned conventional oxygen therapy or NIV through
a facemask.50 Endotracheal intubation was required in
one of 19 patients (5%) assigned NIV and in six of 18
(33%) assigned to ambient oxygen therapy. Patientsreceiving NIV improved more rapidly than those
given simple oxygen.
When the results of the first three studies were
pooled in a meta-analysis, the CPAP group was shown to
have 26% fewer intubations than the ambient pressure group.51
The patients with the most severe respiratory failure
seemed to benefit most from NIV.
CPAP may even be safe and effective in patients
with pulmonary edema due to myocardial infarction.
In a prospective, randomized study of 29 patients
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without cardiogenic shock, nasal CPAP improved
oxygenation and hemodynamics, as well as
demonstrating a decreased mortality rate, compared to
ambient oxygen.52
Potential Dangers Of BiPAP In Congestive HeartFailure And Pulmonary EdemaWhile theoretically beneficial, such clear and compelling
evidence does not exist for BiPAP in the treatment of
CHF. In several case studies, BiPAP was used for
noninvasive respiratory support; intubation rates were
comparable to those found in studies using CPAP (about
9% of selected patients).47
Some studies argue directly against the use of BiPAP
in CHF. In one randomized clinical trial of BiPAP for
emergency patients with respiratory failure, where the
most common diagnosis was pulmonary edema, BiPAP
was associated with increased mortality.13 In this same study,
there was no reduction in the rate of intubation. These
investigators felt that NIV merely delayed intubation in
some patients and caused a worse outcome.
In another trial of 40 consecutive patients with
pulmonary edema, all subjects received standard therapy
consisting of oxygen, furosemide, and morphine sulfate.53
Subjects were then randomized to receive either high-
dose isosorbide-dinitrate vs. BiPAP and standard-dose
nitrates. The study was prematurely terminated by the
safety committee because of the significant deterioration
observed in patients enrolled in the BiPAP arm.
Pearls And Pitfalls Of Noninvasive Ventilation
Why should I use NIV in a patient with acuterespiratory failure?
NIV avoids many of the risks associated with intubation. There
is less likelihood of aspiration and fewer nosocomial
infections such as pneumonia. Patients are more comfortable
and do not require paralysis or sedation. Compared to
intubation, NIV is substantially less expensive for both the
patient and the hospital.
What level evidence is available for NIV?
This depends on the indication.
For COPD, the evidence for NIV is consideredClass II
safe, supported, and considered effective for most patients.For the treatment of pulmonary edema, CPAP is not yet a
standard of care; however, it is probably safe and effective
(Class III ). Note that the current data would suggest that
BiPAP is probablynot safein pulmonary edema, in view of the
increased number of myocardial infarctions that occurred in
one study.
For asthma and pneumonia, the evidence is
indeterminate.
What are the disadvantages of NIV in a patient with acute
respiratory failure?
Noninvasive airway management takes longer to reverse
hypoxia and hypercarbia than does intubation, and the
patient requires frequent physician re-evaluation.
What are the essential elements of success when
NIV is used?
The essential elements of success when NIV is used are
proper patient selection; close monitoring of the patient by
physician, nursing, and respiratory therapy staff; and careful
attention to patient comfort. There is a steep learning curve
for the patient with these devices, and titration should be inthe hands of an experienced respiratory therapist. Of course,
the underlying condition should be aggressively treated
while the ventilator is working.
What is the difference between CPAP, pressure support
ventilation, and BiPAP?
CPAP devices hold a constant positive airway pressure
throughout the respiratory cycle. They may be
full-service ventilators or devices specifically constructed
for this purpose.
BiPAP devices also give a positive airway pressure
throughout the respiratory cycle, with a higher inhalationpressure (IPAP) and a lower pressure during exhalation
(EPAP).3 (BiPAPis actually a trade name for the machine.)
When does a patient need intubation rather than NIV?
The decision to intubate should be made immediately if the
patient suffers a loss of consciousness, worsening respiratory
status, or hemodynamic instability. It may be made later if
there is worsening blood gases or no improvement after a set
period of time.
When can the physician discontinue NIV in the ED?
This requires a weaning process, and close observation
of the patient is essential. Clinically, NIV can be
discontinued when the patients oxygenation can be
maintained at 90% saturation or better with 4 L/min or
less of supplemental oxygen, and when the respiratory
rate is less than 24. At least one study resumed respiratory
support if the respiratory rate increased to greater than
30 respirations per minute, the oxygen saturation fell below
90% despite 4 L/min of supplemental oxygen, or PaCO2
increased by 5 mmHg.42v
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Clinical Pathway: Management Of Patients With HypoxiaAnd/Or Hypercapnia Unresponsive To Supplemental Oxygen
Or Other Conventional Interventions
Theevidence for recommendations is graded using the following scale. For complete definitions, see back page.Class I: Definitely recommended.Definitive, excellent evidence provides support.Class II: Acceptable and useful. Good evidence provides support.Class III: May be acceptable,
possibly useful. Fair-to-good evidence provides support.Indeterminate:Continuing area of research.
This clinical pathway is intended to supplement, rather than substitute, professional judgment and may be changed depending upon apatients individual needs. Failure to comply with this pathway does not represent a breach of the standard of care.
Copyright 2001 Pinnacle Publishing, Inc. Pinnacle Publishing (1-800-788-1900) grants each subscriber limitedcopying privileges for educational distribution within your facility or program. Commercial distribution topromote any product or service is strictly prohibited.
Significantly altered mental status?
Profound hypoxia?
Apnea? Inability to protect airway? Shock? Recent gastric, laryngeal, or esoph-
ageal surgery?
Acute exacerbation of COPD? Failure to improve despite oxygen,-agonists, anticholinergics, and steroids?
Do Not Intubatepatient?
No
Yes Intubate (Class I-II)
Yes
No
Continue conventional therapy(Class II)
Go toClinical Pathway: NoninvasiveVentilation(Class II)
Yes No
Yes
Go toClinical Pathway: Noninvasive Ventilationif patient and/or family desire
prolongation of life (Class indeterminate)
Pneumonia?
Near-drowning? Asthma? Other causes of respiratory failure?
Failure to improve despite maximal conventional therapy?Yes
No
Yes No
Continue conventional therapy(Class indeterminate)
Go toClinical Pathway: Noninvasive
Ventilation(Class indeterminate)
Cystic fibrosis? Febrile neutropenia?
Yes
No
Go toClinical Pathway: Noninvasive Ventilation(Class III)
Congestive heart failure? Failure to improve despite oxygen, nitrates, ACE inhibitors, and diuretics?Yes
No Yes No
Continue conventional therapy(Class II)
Go toClinical Pathway: NoninvasiveVentilation(Class III)
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9/169 Emergency Medicine PracticeJuly 2001
Clinical Pathway: Noninvasive Ventilation
Theevidence for recommendations is graded using the following scale. For complete definitions, see back page.Class I: Definitely recommended.Definitive, excellent evidence provides support.Class II: Acceptable and useful. Good evidence provides support.Class III: May be acceptable,
possibly useful. Fair-to-good evidence provides support.Indeterminate:Continuing area of research.
This clinical pathway is intended to supplement, rather than substitute, professional judgment and may be changed depending upon apatients individual needs. Failure to comply with this pathway does not represent a breach of the standard of care.
Copyright 2001 Pinnacle Publishing, Inc. Pinnacle Publishing (1-800-788-1900) grants each subscriber limitedcopying privileges for educational distribution within your facility or program. Commercial distribution topromote any product or service is strictly prohibited.
Vomiting?
Agitation? Acute trauma?
Cardiac arrhythmias?
Cardiac ischemia or acute myocardial infarction?
Consider intubation or further conventional therapy(Class III)
No
Yes
Explain procedure to patient
Show them and apply the mask Ensure patient is on monitor and pulse oximeter Ensure adequate personnel to monitor patient
CPAP settings: Start with low pressures (5 cmH2O) and increase in increments of 2 cmH
2O as tolerated by the patient.
BiPAP* settings: Typical initial settings for BiPAP are levels of 8-10 cmH2O IPAP and 2-4 cmH
2O EPAP. Titrate to effect. IPAP may
range from 4-24 cmH2O while EPAP may vary from 2-20 cmH
2O.
*Note: Donotuse BiPAP for treatment of CHFuse CPAP instead.(Class indeterminate)
Titrate settings to achieve the following goals: Patient comfort Oxygen saturation greater than 90%
Respiratory rate less than 25 Exhaled tidal volume greater than 7 mL/kg
(Class indeterminate)
Stop NIV and consider intubation or other interventions if: Respiratory arrest or progressive distress Increasing agitation, lethargy, or confusion
Arterial pH below 7.30 that does not rapidly improve Persistent hypoxia Cardiac arrhythmias Hemodynamic instability Persistent vomiting or increased secretions
(Class II)
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Another small trial randomized BiPAP vs. CPAP in
patients with acute pulmonary edema.42 Although BiPAP
lowered the blood pressure, respiratory rates, and
improved ventilation better than CPAP, this study was
also terminated prematurely because patients treated
with BiPAP had significantly more myocardial infarctions
(71% vs 38%). The investigators argued that at least a few
of the myocardial infarctions were present before the
initiation of BiPAP, and surmised that higher intratho-
racic pressures associated with BiPAP may have de-
creased myocardial perfusion. They recommended
further studies using lower settings of BiPAP and more
stringent exclusion of myocardial infarctions. Other
reviewers suggested that inadequate supervision of the
patients, inadequate randomization, and inadequate data
collection during the study contributed to the additional
mortality in the BiPAP arm.54
Although another recent study showed no signifi-
cant complications in 20 patients with CHF who were
treated with BiPAP,10 this study is too small to have
substantial clinical significance.Because of these concerns regarding myocardial infarction,
CPAP appears to be a better modality in pulmonary edema
than BiPAP.
AsthmaStatus asthmaticus is defined as an exacerbation of
asthma that is unresponsive to acute pharmacological
therapy. (See also the February 2001 issue ofEmergency
Medicine Practice, Asthma: An Evidence-Based Manage-
ment Update.) Patients with status asthmaticus
have a significant increase in both inspiratory and
expiratory obstruction that leads to respiratory fatigue
and carbon dioxide retention. In recent years, thenumber of asthmatics who develop acute respiratory
failure has risen significantly.55,56
Theoretically, the use of NIV would be expected to
aid the asthmatic patient in a fashion similar to its well-
studied use in COPD. Researchers postulate that NIV
should decrease airflow obstruction, re-expand atelecta-
sis, reduce the work of breathing, and rest the diaphragm
and inspiratory muscles.
Unfortunately, the potential utility of NIV in asth-
matics has not yet been substantiated by much evi-
dence.57 A few case studies that have reported the use of
NIV in patients with severe asthma suggest a decreased
number of intubations.6,58,59
There are few randomized, controlled studies
that evaluate only asthmatics. In one study, mild-to-
moderate asthmatics were randomized to those given
-agonists via IPPB vs. standard nebulization.60 The
group that received the IPPB had greater improvement
in their peak expiratory flow rate (PEFR) compared to
controls. Two patients (18%) in the CPAP group and
eight patients (73%) in the oxygen group required
endotracheal intubation. Similarly, the mortality in the
CPAP group was significantly lower than the oxygen
group (9% vs 64%; P = 0.02). However, this single study is
probably not sufficient to change current practice.
Validation through subsequent randomized, controlled
trials remains to be seen.
Other IndicationsNear-DrowningPatients who are not spontaneously breathing require
intubation. In such patients, NIV is simply not an option.
However, some near-drowning victims have spontaneous
respirations and go on to develop non-cardiogenic
pulmonary edema. While NIV is effective in these
isolated cases,61 there are no large series that document its
utility for this indication.
Cystic FibrosisNIV may be an alternative to intubation in the patient
with cystic fibrosis who presents to the ED in respiratory
failure. The one-year mortality rate in patients intubated
for cystic fibrosis is 94%.62 While lung transplantation can
improve survival, donors are in short supply.
NIV may help bridge the time between the onset ofrespiratory failure and the availability of a lung trans-
plant.57 One case series of eight patients bolsters this
theory.62 The patient who fails NIV can be subsequently
intubated if necessary.
Obstructive Sleep ApneaNoninvasive pressure support ventilation has long been
used to provide respiratory support for patients with
sleep apnea and obesity hypoventilation.63,64 A large body
of literature documents its usefulness for this chronic
condition. The sleep apnea patient who presents acutely
with hypercapnia or hypoxia may also benefit from NIV.57
Intubation in these patients is often more difficult due tomorbid obesity.
Do Not Intubate PatientsPatients with a variety of illnesses, including advanced
age, poor physiologic condition, or terminal illness (such
as cancer or terminal respiratory failure) may be unsuit-
able candidates for endotracheal intubation. NIV may
give these patients time to complete life-closure tasks.
Others may improve enough to be discharged from the
hospital to hospice care.65
Neutropenic Patients With Respiratory Failure
Patients who have been treated with aggressivechemotherapy and immunosuppression for
hematologic malignancies may develop respiratory
infections and other respiratory complications. Such
complications may include alveolar hemorrhage,
graft-versus-host disease, idiopathic pneumonia syn-
drome, and drug or radiation toxicity.66 Unfortunately,
in these neutropenic patients, endotracheal intubation
is associated with in-hospital mortality rates in excess
of 90%.67 In one small study of neutropenic patients
with respiratory failure, CPAP reduced intubation by
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25%, and all responders to CPAP survived.66 Subsequent
studies confirm the value of NIV in the immunosup-
pressed patients with pulmonary infiltrates, fever, and
acute respiratory failure.68
Pneumonia
The literature regarding the utility of NIV in
pneumonia is mixed.One prospective, randomized
study compared standard treatment plus NIV delivered
through a facemask to standard treatment alone in
56 patients with severe community-acquired pneumo-
nia.69 In those patients with pneumonia and COPD,
NIV reduced the need for endotracheal intubation and
shortened ICU stays. Other studies also suggest that
NIV may improve outcomes in some patients with
community-acquired pneumonia.8,28,70,71 NIV has also
been well-described in the treatment of respiratory
failure due to Pneumocystis carinii.72
However, some data indicate that patients with
pneumonia are the ones most likely to fail NIV.73 In
one small study that included 16 patients with
pneumonia as a primary cause of respiratory distress,NIV failed to prevent the need for intubation.11 Clearly,
further research regarding the utility of CPAP or BiPAP
in pneumonia is necessary.
Contraindications To Noninvasive Ventilation
NIV with positive pressure generally requires an alert,
breathing patient. (Table 3summarizes some
contraindications to NIV.) The hypercapnic COPD patient
with mild alterations of mental status may improve
rapidly when NIV is started, but such a patient must be
carefully monitored. If the patient is unable to cooperate
with fitting or wearing a mask, then NIV is not appropri-
ate. Both apnea and coma are absolute contraindications
to NIV.
If the patient requires a definitive airway for
prevention of aspiration or management of secretions,
then intubation will be necessary. Significant facial
trauma may make the mask seal that is necessary for NIV
impossible. Because of concerns regarding tension
pneumothorax, patients with a pneumothorax or
significant chest trauma are not candidates for NIV
(although the use of NIV to treat a patient with severe
chest trauma has been described74).
Hemodynamic instability is generally considered an
absolute contraindication for NIV, while myocardial
infarction and ventricular arrhythmias are relative
contraindications. Patients with excessive secretions are
poor candidates for NIV, particularly with a full
facemask. Frequent expectoration interferes with positive
pressure as the patient opens his or her mouth, even with
a nasal mask.
Although the possibility of barotrauma or disruption
of a healing wound is small, it could be catastrophic in
the postoperative patient. For this reason, the patientwith recent tracheal, oropharyngeal, esophageal, or
gastric surgery should not undergo NIV. While a recent
tracheostomy or an open tracheal stoma is a contraindica-
tion, a remote, healed tracheostomy (with no open stoma)
is not.
Complications Of NIV
There is a low rate of complications associated with NIV,
and most are not dangerous.5 The most pressing, of
course, is failure of the technique (as described in a
subsequent section). (See alsoTable 4.)
Local ComplicationsFacial skin necrosis occurs in about 10%-15% of
NIV patients.35,40-42,69 A skin patch or non-adherent
dressing may be applied over the bridge of the nose
to prevent erosions.
Systemic ComplicationsWhile pneumonia is far less common in patients
treated with NIV than with intubation, it can still
occur.8 Barotrauma, however, is possible with any
positive pressure ventilation technique. This is particu-
larly true when patients with underlying pulmonary
disease are subjected to high airway pressures. Nonethe-less, reports of barotrauma (including pneumomediasti-
num and pneumothorax) occurring during NIV are
Table 3. Contraindications To Noninvasive Ventilation.
Absolute Apnea Shock Inability to protect the airway Significantly altered mental status Pneumothorax
Recent gastric, laryngeal, or esophageal surgery Significant facial fractures (especially those involving
cribriform plate)
Inability to cooperate with fitting and wearing mask Rapid deterioration
Inadequate staff to closely monitor patientfor deterioration
Relative Nausea and vomiting Agitation Cardiac arrhythmias Cardiac ischemia or acute myocardial infarction (an
absolute contraindication in some studies) Significant chest trauma
Table 4. Complications Of Noninvasive Ventilation.
Facial skin necrosis Pneumonia Gastric distention Barotrauma Failure of the technique
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12/16Emergency Medicine Practice 12 July 2001
extremely rare.75
Gastric distention is also uncommon with NIV
(about 2%-5%). Gastric distention is decreased
when the peak positive pressure is less than the
resting upper esophageal sphincter pressure (33 12
mmHg).76 Nurses and therapists should examine
patients frequently for signs of abdominal distention,
as this may lead to vomiting and subsequent aspira-
tion. If distention occurs, insert a nasogastric tube and
apply suction.
Failure Of The TechniqueThe most common complication of NIV is failure of the
technique. Close monitoring of the respiratory rate,
exhaled tidal volume, oxygen saturation, use of accessory
muscles, dyspnea level, and blood gases clearly plays a
role in successful therapy.
When the patient is obviously not improving,
then the clinician should strongly consider intubation.
(See alsoTable 5.) The decision to intubate should be
made immediately if the patient suffers a loss of con-
sciousness, worsening respiratory status, or hemody-namic instability. The decision is less urgent if there is a
gradual worsening of blood gases or no improvement
after a set period of time.
Summary
NIV may be the preferred initial treatment of patients
with hypercapnic acute respiratory failure in whom the
clinical condition can be readily reversed, when airway
control is not needed, and when the patient is hemody-
namically stable. Postponing intubation appears to be the
major complication, and in most patients this does not
appear to have serious consequences.NIV is a complex and labor-intensive venture. It
requires experienced nursing and respiratory staff who
are able and willing to closely monitor the critical patient.
For this reason, it may not be suitable for the over-
crowded and understaffed ED. Success will entail a
partnership with respiratory therapy to effectively utilize
NIV, and using the equipment frequently may improve
expertise. Keeping a machine in the ED can maximize
early intervention.
When starting this procedure, it is essential to
have intubation equipment at hand and experienced
practitioners readily available to intubate the
failing patient. v
References
Evidence-based medicine requires a critical appraisal of
the literature based upon study methodology and
number of subjects. Not all references are equally robust.
The findings of a large, prospective, randomized, andblinded trial should carry more weight than a case report.
To help the reader judge the strength of each
reference, pertinent information about the study, such as
the type of study and the number of patients in the study,
will be included in bold type following the reference,
where available. In addition, the most informative
references cited in the paper, as determined by the
authors, will be noted by an asterisk (*) next to the
number of the reference.
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Table 5. Reasons To Abandon Noninvasive Ventilation.
Respiratory arrest Respiratory rate greater than 35 Progressive respiratory distress
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(Randomized; 41 adult patients)
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46. Kelly AM, Georgakas C, Bau S, et al. Experience with theuse of continuous positive airway pressure (CPAP) therapyin the emergency management of acute cardiogenicpulmonary oedema.Aust N Z J Med 1997;27:319-322.(Retrospective chart review; 75 patients)
47. Sacchetti AD, Harris RH, Paston C, et al. Bi-level positiveairway pressure support system use in acute congestiveheart failure: Preliminary case series.Acad Emerg Med1995;2:714. (Retrospective case series; 22 adult patients)
48. Rasanen J, Heikkila J, Downs J, et al. Continuous positiveairway pressure by face mask in acute cardiogenicpulmonary edema.Am J Cardiol 1985;55:296-300. (Random-ized; 40 adult patients)
49.* Lin M, Yang YF, Chiang HT, et al. Reappraisal of continu-ous positive airway pressure therapy in acute cardiogenic
pulmonary edema. Short-term results and long-termfollow up. Chest 1995;107:1379-1386. (Randomized; 100adult patients)
50. Masip J, Betbese AJ, Paez J, et al. Non-invasive pressuresupport ventilation versus conventional oxygen therapy inacute cardiogenic pulmonary oedema: a randomised trial.
Lancet 2000;356(9248):2126-2132. (Randomized, controlled;40 patients)
51. Pang D, Keenan SP, Cook DJ, et al. The effect of positivepressure airway support on mortality and the need forintubation in acute cardiogenic pulmonary edema. Chest1998;114:1185-1192. (Meta-analysis)
52. Takeda S, Nejima J, Takano T, et al. Effect of nasal continu-ous positive airway pressure on pulmonary edemacomplicating acute myocardial infarction.Jpn Circ J1998;62(8):553-558. (Randomized, controlled; 29 patients)
53.* Sharon A, Shpirer I, Kaluski E, et al. High-dose intravenousisosorbide-dinitrate is safer and better than Bi-PAPventilation combined with conventional treatment forsevere pulmonary edema.J Am Coll Cardiol 2000;36(3):832-837. (Randomized, controlled; 40 patients)
54. Ntoumenopoulos G. Limitations to study on noninvasiveventilation. Chest 1999;115:303. (Letter to the editor)
55. Centers for Disease Control and Prevention. Forecastedstate-specific estimates of self-reported asthma preva-lenceUnited States, 1998.MMWR Morb Mortal Wkly Rep1998;47:1022-1025. (Retrospective)
56. Mannino DM, Homa DM, Pertowski CA, et al. Surveillancefor asthmaUnited States, 1960-1995.MMWR Morb MortalWkly Rep 1998;47:1-28. (Retrospective)
57.* Meduri GU. Noninvasive positive pressure ventilation in
patients with acute respiratory failure. Clin Chest Med1996;17:513. (Review [this review is quite complete,although a bit dated in 2001])
58. Meduri GU, Abou-Shala N, Fox RC, et al. Noninvasive facemask mechanical ventilation in patients with acute
hypercapnic respiratory failure. Chest 1991;100:445-454.(Case series)
59. Meduri GU, Cook TR, Turner RE, et al. Noninvasive
positive pressure ventilation in status asthmaticus. Chest1996;110:767-774. (Case series; 17 adult patients)
60. Pollack CV, Fleish KB, Dowsey K. Treatment of acute
bronchospasm with beta-adrenergic agonist aerosolsdelivered by a nasal bilevel positive airway pressurecircuit.Ann Emerg Med 1995;26:552-557. (Randomized;
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61. Dottorini M, Eslami A, Baglioni S, et al. Nasal-continuouspositive airway pressure in the treatment of near-drowningin freshwater. Chest 1996;110:1122-1124. (Case report;2 patients)
62. Granton JT, Kesten S. The acute effects of nasal positivepressure ventilation in patients with advanced cysticfibrosis. Chest 1998;113:1013-1018. (Case report; 8 patients)
63. Strumpf DA, Carlisle CC, Millman RP, et al. Anevaluation of the Respironics BPAP Bilevel CPAP
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independently adjusted inspiratory and expiratory positiveairway pressures via nasal mask. Chest 1990;98:317-324.
65. Muir JF, Cuvelier A, Verin E, et al. Noninvasive mechanicalventilation and acute respiratory failure: indications andlimitations.Monaldi Arch Chest Dis 1997;52:56-59. (Review)
66.* Hilbert G, Gruson D, Vargas F, et al. Noninvasive continu-ous positive airway pressure in neutropenic patients withan acute respiratory failure requiring intensive care unitadmission. Crit Care Med 2000;28:3185-3190. (Prospective,uncontrolled; 129 adult patients enrolled, 64 patientsactually studied)
67. Rubenfeld GD, Crawford SW. Withdrawing life support
from mechanically ventilated recipients of bone marrowtransplants: A case for evidence based guidelines. AnnIntern Med 1996;125:625-633. (Retrospective, nested, case-control; 865 total patients, 56 selected patients, 106
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tion in immunosuppressed patients with pulmonaryinfiltrates, fever, and acute respiratory failure [see com-ments]. N Engl J Med 2001;344(7):481-487. (Prospective,randomized, controlled; 52 patients)
69. Confalonieri M, Potena A, Carbone G, et al. Acute respira-tory failure in patients with severe community-acquiredpneumonia. A prospective randomized evaluation ofnoninvasive ventilation [see comments].Am J Respir CritCare Med 1999;160(5 Pt 1):1585-1591. (Prospective, random-ized, controlled; 56 patients)
70. Brett A, Sinclair DG. Use of continuous positive airwaypressure in the management of community acquiredpneumonia. Thorax 1993;48(12):1280-1281. (Case report;3 patients)
71. LHer E, Moriconi M, Texier F, et al. Non-invasive continu-ous positive airway pressure in acute hypoxaemicrespiratory failureexperience of an emergency depart-ment. Eur J Emerg Med 1998;5(3):313-318. (Retrospective;
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Physician CME Questions
1. Noninvasive ventilation uses which of the
following techniques?
a. Constant positive airway pressure support
b. Pressure support ventilation
c. External negative pressure ventilation
d. All of the above are techniques of
noninvasive ventilation.
2. Intubation of the trachea is considered a gold
standard in the management of respiratory
failure. Any technique that deviates from this
standard must demonstrate:
a. more risks.
b. greater value to the hospital.
c. evidence of therapeutic benefits provided.
d. lower cost.
3. Which of the following is most appropriate
for the patient who will require long-term
ventilator support?
a. Traditional ventilation in the
noninvasive role
b. Dedicated noninvasive venti lator machine
c. Volume-based NIV machine
d. External negative pressure ventilator
4. Which of the following presents the most signifi-
cant threat in a patient who is currently being
treated with noninvasive ventilation?
a. Agitation or combativeness
b. Diarrhea
c. Minor nasal congestion
d. A single episode of vomiting
5. Techniques of positive pressure ventilation draw
from which other discipline?
a. Aviation
b. Metallurgy
c. Radiology
d. Hoover vacuum cleaner manufacturing
6. BiPAP:
a. is a trade name for a specific pressure
support ventilator.
b. cycles between peak inspiratory pressure and
peak end expiratory pressure.c. terminates inspiratory flow when the ventila-
tor cycles from IPAP to EPAP.
d. all of the above.
7. What is the most likely serious complication
of noninvasive ventilation?
a. Facial skin necrosis
b. Pulmonary barotrauma
c. Gastric distention
d. Failure of the technique
8. CPAP appears to recruit lung mechanics by:
a. recruiting normal alveoli.
b. flattening pulmonary compliance.
c. reducing the work of breathing.
d. increasing patient agitation.
9. Which of the following techniques of
noninvasive ventilation is most
appropriate for the patient who has a
beard and mustache?
a. Facemask
b. Nasal pads
c. Nasal mask
d. NIV cannot be performed in a patient
with facial hair
10. Which of the following diseases is not appropri-
ate to treat with noninvasive ventilation?
a. Narcotic overdose with pulmonary edema
b. Asthma
c. COPD
d. Pulmonary edema
11. Which of the following is a contraindication
to noninvasive ventilation?
a. Ruptured eardrum
b. Remote history of tracheostomy with
healed-over stoma
c. Myocardial infarction
d. Recent small bowel surgery
12. Which of the following is an advantage of
noninvasive ventilation?
a. The airway is better protected with
noninvasive ventilation.b. The patient s disease corrects
more quickly.
c. The patient is more comfortable.
d. The patient needs very little monitoring.
13. Noninvasive ventilation should not
routinely be considered as a therapeutic
option for:
a. an acute exacerbation of COPD.
b. patients suffering from a narcotic overdose.
c. respiratory failure in patients with
cystic fibrosis.
d. neutropenic patients with respiratory failure.
14. In which of the following scenarios should the
emergency physician switch from noninvasive
ventilation to intubation?
a. If the patient develops bradycardia or signifi-
cant tachycardia
b. If the patient has a loss of consciousness
c. If the patient becomes increasingly agitated,
lethargic, or confused
d. If any of the above occur
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16/16
Class I Always acceptable, safe Definitely useful Proven in both efficacy and
effectiveness
Level of Evidence: One or more large prospective
studies are present (withrare exceptions)
High-quality meta-analyses
Study results consistentlypositive and compelling
Class II Safe, acceptable Probably useful
Level of Evidence: Generally higher levels
of evidence Non-randomized or retrospec-
tive studies: historic, cohort, orcase-control studies
Less robust RCTs Results consistently positive
Class III May be acceptable Possibly useful Considered optional or
alternative treatments
Level of Evidence: Generally lower or intermedi-
ate levels of evidence
Case series, animal studies,consensus panels
Occasionally positive results
Indeterminate Continuing area of research No recommendations until
further research
Level of Evidence: Evidence not available
Higher studies in progress Results inconsistent,
contradictory Results not compelling
Significantly modified from: The
Emergency Cardiovascular Care
Committees of the American Heart
Association and representatives
from the resuscitation councils of
ILCOR: How to Develop Evidence-
Based Guidelines for Emergency
Cardiac Care: Quality of Evidence
and Classes of Recommendations;
also: Anonymous. Guidelines forcardiopulmonary resuscitation and
emergency cardiac care. Emer-
gency Cardiac Care Committee and
Subcommittees, American Heart
Association. Part IX. Ensuring
effectiveness of community-wide
emergency cardiac care.JAMA
1992;268(16):2289-2295.
Class Of Evidence Definitions
Each action in the clinical pathways section ofEmergencyMedicine Practicereceives an alpha-numerical score based onthe following definitions.
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should not be used for making specific medical decisions. The materials containedherein are not intended to establish policy, procedure, or standard of care.EmergencyMedicine Practiceis a trademark of Pinnacle Publishing, Inc. Copyright2001 PinnaclePublishing, Inc. All rights reserved. No part of this publication may be reproduced inany format without written consent of Pinnacle Publishing, Inc. Subscription price:$249, U.S. funds. (Call for international shipping prices.)
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Physician CME Information
This CME enduring material is sponsored by Mount Sinai School ofMedicine and has been planned and implemented in accordance withthe Essentials and Standards of the Accreditation Council for ContinuingMedical Education. Credit may be obtained by reading each issue andcompleting the post-tests administered in December and June.
Target Audience:This enduring material is designed for emergencymedicine physicians.
Needs Assessment:The need for this educational activity wasdetermined by a survey of medical staff, including the editorial boardof this publication; review of morbidity and mortality data from theCDC, AHA, NCHS, and ACEP; and evaluation of prior activities foremergency physicians.
Date of Original Release:This issue ofEmergency MedicinePracticewas published July 2, 2001. This activity is eligible forCME credit through July 2, 2004. The latest review of this materialwas June 29, 2001.
Discussion of I nvestigational Information: As part of thenewsletter, faculty may be presenting investigational informationabout pharmaceutical products that is outside Food and DrugAdministration approved labeling. Information presented as part ofthis activity is intended solely as continuing medical education and isnot intended to promote off-label use of any pharmaceutical product.Disclosure of Off-Label Usage:This issue ofEmergency Medicine Practicediscusses no off-label use of any pharmaceutical product.
Faculty Disclosure:In compliance with all ACCME Essentials, Standards,and Guidelines, all faculty for this CME activity were asked to completea full disclosure statement. The information received is as follows: Dr.Stewart, Dr. Radeos, and Dr. Della-Giustina report no significantfinancial interest or other relationship with the manufacturer(s) of anycommercial product(s) discussed in this educational presentation.
Accreditation: Mount Sinai School of Medicine is accredited by theAccreditation Council for Continuing Medical Education to sponsorcontinuing medical education for physicians.
Credit Designation:Mount Sinai School of Medicine designates thiseducational activity for up to 4 hours of Category 1 credit toward theAMA Physicians Recognition Award. Each physician should claim onlythose hours of credit actually spent in the educational activity.Emergency Medicine Practiceis approved by the American College ofEmergency Physicians for 48 hours of ACEP Category 1 credit (perannual subscription).
Earning Credit: Physicians with current and valid licenses in the UnitedStates, who read all CME articles during eachEmergency MedicinePracticesix-month testing period, complete the CME Evaluation Formdistributed with the December and June issues, and return itaccording to the published instructions are eligible for up to 4 hoursof Category 1 credit toward the AMA Physicians Recognition Award(PRA) for each issue. You must complete both the post-test and CMEEvaluation Form to receive credit. Results will be kept confidential.CME certificates will be mailed to each participant scoring higher than70% at the end of the calendar year.
15. In which of the following scenarios is
NIV contraindicated?
a. If the patient requires a secure airway
b. If the patient has poor air movement
with COPD
c. If the patient has stable atrial fibrillation
d. If the patient suffers from sleep apnea
16. Although intubation is a gold standard,
it has certain inherent risks. Which of the
following risks is lower for noninvasive
ventilation than intubation?
a. Physical risks relating to the insertion
of the endotracheal tube
b. Infection
c. Avoidance of sedation and paralysis
d. All of the above are lessened with
noninvasive ventilation