Noninvasive Airway Management Techniques How and When to Use Them

7/29/2019 Noninvasive Airway Management Techniques How and When to Use Them

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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.)


2/16Emergency Medicine Practice 2 July 2001

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.


3/163 Emergency Medicine PracticeJuly 2001

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,



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



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



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



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

Continued on page 10



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)



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)



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

Continued from page 7



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



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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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;

100 patients)

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

Device of delivery of assisted ventilation. Respir Care1990;35:415-422.64. Sanders MH, Kern N. Obstructive sleep apnea treated by

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

selected controls)68.* Hilbert G, Gruson D, Vargas F, et al. Noninvasive ventila-

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


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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Emergency Medicine Practice(ISSN 1524-1971) is published monthly (12 times per year)by Pinnacle Publishing, Inc., 1000 Holcomb Woods Parkway, Building 200, Suite 280,Roswell, GA 30076-2587. Opinions expressed are not necessarily those of thispublication. Mention of products or services does not constitute endorsement. Thispublication is intended as a general guide and is intended to supplement, rather thansubstitute, professional judgment. It covers a highly technical and complex subject and

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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

Documents

Noninvasive Airway Management Techniques How and When to Use Them