The AASM Manual for the Scoring of Sleep and Related Events is not a guideline or practice parameter, and uses slightly different terminology. The key on page 15 indicates that "recommended," "alternative," and "optional" rules are all methods acceptable by AASM for scoring. An accredited center must follow all of the rules, but based on the discretion of the clinician or investigator a specific center may use "alternative" or "optional" rules in the place of the "recommended" rule. The use of "alternative" or "optional" rules would not create any risk to accreditation.
The term "recommended AASM guidelines" in the accreditation standards refers to the set of guideline papers published by the AASM Practice Parameters. Each paper has recommendations based on evidence and/or consensus with terms ("standard," "guideline" or "option") that are used to reflect the strength of evidence and/or consensus. An accredited center must follow all of the "standard" recommendations, and may or may not follow the "guidelines" or "options."
The Steering Committee provides responses to specific questions sent to the national office by
e‐mail to email@example.com such as the one you are reading. Questions of more general
interest have been posted over the past year at this website.
The Steering Committee referred to in the “Clinical Guidelines for the Use of Unattended
Portable Monitors in the Diagnosis of Obstructive Sleep Apnea” was appointed the AASM Board
of Directors to develop, in conjunction with task forces and approval of the AASM Board, the
scoring rules published in “The Scoring of Sleep and Associated Events: Rules, Terminology, and
No, for AASM accredited centers and laboratories, all new equipment purchased after July 1,
2008 will need to be in compliance with the technical requirements on pages 19‐21. However,
even with existing equipment, by July 1, 2008, you will need to:
The manual does not specifically require audio recording. Most laboratories incorporate it within the required video recording process however because there are so many clinical situations in which audio is extremely useful, including but not limited to bruxism, snoring, behavioral disorders, parasomnias, seizures and catathrenia.
You are correct. The Scoring Manual assumes that a single digital resolution standard is applied to all channels. In fact, 3 bit resolution would be adequate for the body position sensor. The Body Position channel should be exempt from the digital resolution standard. However, the recommended sampling rate of 1 Hz remains in effect.
Widescreen monitors with a minimum resolution of 1920×1080 (standard for HDMI with aspect ratio of 16:9, also known as "HD 1080") are also acceptable for PSG display.
No, this would be scored as W using IV.2.B.3.
Arousals in R do not end R. A 3 or 5 second shift to alpha in R requires a 1 second rise in EMG to
constitute an arousal in R under Rule V. An epoch containing alpha for greater than 15 seconds
would be scored W, ending R.
Time with the patient disconnected from the recording equipment should be scored as stage W. Brief episodes of sleep during this time, if they occur, are not considered significant for the stage scoring summary.
The ability to count respiratory events if they ”touch” sleep (R10) and reporting observations in the narrative (R5) help tie respiratory events to sleep fragmentation. A1 helps count arousals related to drowsiness/wake. Using epoch scoring rules one could not have a theoretical average of >1 arousal/epoch in wake (for 2 arousals, 10 seconds + 10 seconds = 20 seconds and thus sleep would be the majority of the epoch and would be scored as an epoch of sleep). Excessive scoring of arousals in wake does not seem a practical problem.
Note 1. in VII.1. is correct as stated: An LM should not be scored if it occurs during a period from 0.5 seconds preceding an apnea or hypopnea to 0.5 seconds following an apnea or hypopnea. This period is inclusive and no LMs should be scored.
There is insufficient evidence to support the use of RIP as an alternative to standard flow measurements in respiratory event scoring in clinical settings. Given the careful evidence review and consensus underpinning the decision to employ nasal pressure and thermal sensors for flow detection detailed in the review “The scoring of respiratory events in sleep: reliability and validity” [ J Clin Sleep Med 2007;3:169‐200], nasal pressure and thermal sensors are recommended for flow detection for both the laboratory setting (“The Scoring of Sleep and Associated Events: Rules, Terminology, and Technical Specifications”) and in portable monitoring (“Clinical Guidelines for the Use of Unattended Portable Monitors in the Diagnosis of Obstructive Sleep Apnea”).
Respiratory events require a minimum duration of 10 seconds in adults and 2 breaths in children. The abnormality must last this specified duration though amplitude criteria are required for only 90% of the duration. Any event that does not have an abnormality lasting a total of 10 seconds [or 2 breaths in children] cannot be defined as an apnea or hypopnea. Abnormalities lasting only 9 seconds are not scored as respiratory events in adults. The published FAQ R12 states “Scoring of hypopneas and apneas requires a minimum duration of 10 seconds. If the amplitude criteria are met during any contiguous 9 seconds of an event that lasts 10 seconds or longer then the event should be scored even if the duration of the amplitude reduction does not constitute 90% of the total event duration.” Thus relatively rare events that incorporate only 7 or 8 seconds meeting amplitude criteria will not meet criteria for an event.
Many phenomena that occur during the recording sleep studies were not included in the
scoring manual because of their uncertain significance. Deep breaths that accompany arousals may be followed by single central apneas though the significance of this phenomenon is not
1) We don’t understand how intercostal EMG channels can be quantitative. We use
intercostal EMG channels. This is a basic EMG channel. Would this channel be quantitative if
we added a grid to the display so that we could visualize the number of microvolts that
represent the EMG changes? Is there some other way to make this parameter quantitative?
All surface electrical recordings are quantitative. Although voltage specifications for
quantitative EMG are required for PLMs, there is no voltage requirement in recording
respiratory muscle activity.
2) A further question is how does quantitative assessment of ventilatory effort allow
someone to deduce whether or not a hypopnea is obstructive? Is the answer that when the
efforts increase but the airflow does not then the hypopnea is obstructive? This is
counterintuitive for me since the airflow channels are not quantitative and yet, to deduce
whether or not an event is obstructive, they are used with the efforts channels which would
be quantitative. (I would wonder why flattening of nasal pressure signal, paradoxical efforts
in RIP channels or snoring couldn’t be used as signs of obstruction.)
Classification of apneas as obstructive, central and mixed is recommended [VII.3.B] but
classification and reporting of hypopneas as obstructive, central, or mixed was not
recommended because of the lack of evidence for a reliable method for these classifications.
It is recognized, however, that some respiratory events meeting criteria for hypopnea may
occur as a result of decreased effort [for instance during REMs] rather than obstruction. The
note VII.5.1 was provided for those who would like to add interpretive comment that would
support obstructive or non‐obstructive evidence. Reduction in semiquantitative measure of
airflow with increase effort would suggest obstruction. We also agree that inspiratory flow
flattening and snoring suggest obstruction. Paradoxical movement is may be present during
REM [due to chest wall inhibition] without obstruction.
The pre-event baseline must be determined from the oximetry reading prior to each event. A single pre-event baseline obtained during any period of stable, non-event containing sleep cannot be used. The pre-event baseline should be defined as the closest stable oximetry reading prior to the event or in the case where events are sufficiently frequent such that recovery of oxygenation does not occur, the highest value prior to the event.
End Tidal CO2 is considered adequate to detect the presence or absence of air flow, but does not provide the same amplitude variation as the nasal pressure signal. Therefore, in the setting when hypoventilation MUST be monitored and End Tidal CO2 is VALIDATED, End Tidal CO2 may be used as an ALTERNATIVE to the thermistor but only for apnea detection.
As specified in the notes following the technical considerations 1A and 1B on page 48, end‐tidal PCO2 may be used as an alternative sensor for the detection of apneas only when the oronasal thermal sensor is not reliable. It may not be used for detection of hypopneas.
Slippage of the inductance plethysmography belts is common in children and the sum channel
is not considered to be an accurate measure of flow. Airflow should be measured at the nose in