|Sleep Apnea Syndrome (2)
Sleep Apnea Syndrome |
Apnea CPAP Rx
Indications for Positive Airway Pressure Treatment
of Adult Obstructive Sleep Apnea Patients *
Daniel I. Loube, Peter C. Gay, Kingman P. Strohl, Allan I. Pack,
David P. White, Nancy A. Collop 6 MD, FCCP
(Chest Volume 115 Number 3 March 1999 The
American College of Chest Physicians )
Treatment modalities for OSA with PAP include continuous positive airway
pressure, bilevel or variable PAP, and autotitrating PAP. This guidance on
the appropriate criteria for PAP use in OSA is based on widely acknowledged
peer-reviewed studies and widely accepted clinical practice. These criteria
reflect current opinion on the appropriate clinical management of OSA in
lieu of data pending from the Sleep Heart Health Study and upcoming outcome
studies. This document is not intended to provide a complete review and analysis
of the OSA clinical literature. The key to the success of this document is
to foster consensus within and outside the clinical sleep community by providing
a common sense and easily understood approach to the treatment of OSA with
CPAP - continuous positive airway pressure
EMG - electromyogram
EOG - electro-oculogram
NPSG - nocturnal polysomnography
OSA - obstructive sleep apnea
PAP - positive airway pressure
RDI - respiratory disturbance index
RERA - respiratory effort-related arousal
I. Accepted Diagnostic Techniques
A. Standard Diagnostic Nocturnal Polysomnography (NPSG)
Based on the 1997 American
Sleep Disorders Association Indications for Polysomnography Task Force Report
NPSG is indicated for the diagnosis of possible obstructive sleep apnea (OSA).
It includes recording and analysis of the following parameters: EEG,
electro-oculogram (EOG), electromyogram (EMG), oronasal airflow, chest wall
effort, body position, snore microphone, ECG, and oxyhemoglobin saturation.
The duration of a diagnostic NPSG is at least 6 h (with the exception of
the diagnostic portion of a split-night study, which is at least 2 h in duration;
refer to section IB).
6-h minimum duration of a diagnostic NPSG is preferred, which allows for
the assessment of variability related to sleep stage and position with respect
to the frequency of obstructive respiratory events and the occurrence of
other types of nocturnal events such as periodic limb movements.
Standard diagnostic NPSG may be performed in a health-care facility or in
the patient's home with a trained technologist in attendance. The use of
unattended, standard diagnostic NPSG in the patient's home is not a validated
clinical technique. Diagnostic NPSG must be interpreted by a physician trained
in the evaluation and treatment of OSA patients.
B. Split-Night Study NPSG
Based on the 1997 American Sleep Disorders Association
Indications for Polysomnography Task Force Report  :
Patients with a respiratory disturbance index (RDI) > 40 events
per hour during the first 2 h of a diagnostic NPSG receive a split-night
study NPSG, of which the final portion of the NPSG is used to titrate continuous
positive airway pressure (CPAP).
Split-night studies may be considered for patients with an RDI of 20 to 40
events per hour, based on clinical observations, such as the occurrence of
obstructive respiratory events with a prolonged duration or in association
with severe oxygen desaturation.
A minimum of 3 h of sleep is preferred to adequately titrate CPAP after this
treatment is initiated.
Split-night studies require the recording and analysis of the same parameters
as a standard diagnostic NPSG.
On occasion, an additional full-night CPAP titration NPSG may be required,
if the split-night study did not allow for the abolishment of the vast majority
of obstructive respiratory events or prescribed CPAP treatment does not control
C. Limited-Channel Diagnostic NPSG
May be indicated for patients with a high pretest probability of OSA based
on validated screening algorithms such as those investigated by Maislin et
al and Kushida et al.
Limited-channel diagnostic NPSG should include the following minimum parameters:
oronasal airflow, chest wall effort, ECG, and oxyhemoglobin saturation.
Limited-channel NPSG is not effective in distinguishing sleep from wake or
determining sleep stage.
Limited-channel NPSG is less accurate than a standard NPSG in determining
the number of obstructive respiratory events and does not detect non-OSA
sleep disorders that may coexist with OSA.
II. Diagnostic Criteria (Employing the
Previously Specified Techniques)
Based on the American Sleep Disorders Association Criteria for Measurements,
Definitions, and Severity Ratings of the Sleep Related Breathing Disorders
Task Force Report :
Apnea is defined as the cessation of airflow for 10 seconds.
Hypopnea is defined as a recognizable, transient reduction, but not a complete
cessation of breathing 10 s.
A 50% decrease in the amplitude of a validated measure of breathing or a
< 50% amplitude reduction that is associated with either an oxygen
desaturation of 3% or an arousal must be evident.
Obstructive apneas and hypopneas are typically distinguished from central
events by the detection of respiratory efforts during the event.
A respiratory effort-related arousal (RERA) is an event characterized by
increasing respiratory effort for 10 s leading to an arousal from sleep but
which does not fulfill the criteria for a hypopnea or apnea. A RERA is detected
with nocturnal esophageal catheter pressure measurement, which demonstrates
a pattern of progressive negative esophageal pressures terminated by a change
in pressure to a less negative pressure level associated with an arousal.
Novel techniques are available that may allow for increased technical ease
in the detection of RERAs.
The RDI is defined as the number of obstructive apneas, hypopneas, and RERAs
per hour averaged over the course of at least 2 h of sleep as determined
III. Treatment Criteria
CPAP treatment is indicated for all OSA patients with an RDI 30 events
per hour, regardless of symptoms, based on the increased risk of hypertension
evident from the Wisconsin sleep cohort data.
Treatment with CPAP is indicated for patients with an RDI of 5 to 30 events
per hour accompanied by symptoms of excessive daytime sleepiness, impaired
cognition, mood disorders, insomnia, or documented cardiovascular diseases
to include hypertension, ischemic heart disease, or stroke. The use of
an RDI of 5 events per hour as the minimal threshold value for CPAP treatment
of symptomatic OSA patients is supported by the studies of Redline et al
and Engleman et al that demonstrated improvements in symptoms and daytime
Treatment with CPAP is not indicated for asymptomatic patients without
cardiovascular diseases who demonstrate mild OSA on diagnostic NPSG.
Only physicians trained in the evaluation and treatment of OSA patients shall
prescribe CPAP for this indication.
IV. CPAP Titration
On a subsequent night following a diagnostic NPSG or following the diagnostic
portion of a split-night study, OSA patients receive CPAP titration to specify
the lowest CPAP level, which abolishes obstructive apneas, hypopneas, RERAs,
and snoring in all sleep positions and sleep stages.
Minimum parameters to be monitored and analyzed with CPAP titration NPSG
include the following: EEG, EOG, EMG, oronasal airflow, chest wall effort,
body position, snore microphone, ECG, and oxyhemoglobin saturation. Inclusion
of EEG, EOG, and EMG in CPAP titration NPSG parameters allows for detection
of arousals and avoids possible undertitration due to otherwise unrecognized
episodes of wakefulness and detection of various sleep stages to allow for
the optimization of manually specified pressure requirements.
V. Bilevel Positive Airway Pressure
Bilevel positive airway pressure (PAP) allows for independent adjustment
of inspiratory and expiratory pressures. A timed, back-up rate capability
is not required for OSA treatment.
A trial of bilevel PAP may be indicated for OSA patients who cannot tolerate
CPAP due to persistent massive nasal mask air leakage or discomfort exhaling
against positive pressure.
A trial of bilevel PAP may be indicated for OSA patients with concomitant
nocturnal breathing disorders to include restrictive thoracic disorders,
COPD, and nocturnal hypoventilation.
Although initial acceptance of PAP treatment is increased with the availability
of bilevel PAP, it may not be routinely indicated as an alternative to CPAP
in OSA patients because there may not be an increase in the hours of use.
An additional NPSG may be required to titrate bilevel PAP if CPAP failure
VI. Autotitrating PAP
Autotitrating PAP allows for the titration of CPAP without the immediate
involvement of a technologist.
Recent studies suggest that some autotitrating PAP systems are effective
in determining the optimal CPAP setting for most OSA patients.
Treatment with autotitrating PAP systems in some studies shows slight increases
in adherence as compared with CPAP.
An additional NPSG may be required to titrate CPAP if autotitrating PAP treatment
VII. Repeat NPSG
Indications for repeat NPSG are persistence of symptoms despite adherence
to PAP treatment and assessment of treatment response to upper airway surgical
procedures, oral appliances, or significant sustained weight change (>
VIII. Adherence to PAP Treatment
Efforts directed at OSA patient education are warranted for at least the
first month of PAP treatment to promote effective long-term adherence with
treatment. This education may be provided by physicians, specially
trained technologists, or nurses.
To enhance and ensure PAP adherence and equipment maintenance, follow-up
with a physician or a designated surrogate should occur at least once after
the initiation of PAP treatment, and thereafter on at least a yearly basis.
Adjustments or changes in the PAP-patient interface are not uncommon and
may be indicated, due to difficulties with mask fit leading to skin abrasion,
massive air leak, or to mask, tubing, or rebreathing valve breakage.
Adequate adherence to PAP is defined as > 4.5 h of PAP use per night on
a routine basis.
Maximal improvement in neurocognitive symptoms can require as long as 2 months
of PAP treatment.
Apnea and Periodic Breathing during Sleep
New England Journal of Medicine -- September 23, 1999 -- Vol. 341, No. 13