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T.6. AASM guideline III.1.C.1. states that the resolution of the digital screen must be at least 1600x1200. It is becoming cost prohibitive to find the appropriate device now that the industry has standardized on widescreen models for LCD displays. Many of the widescreen models have a vertical resolution of 1080 (vs 1200). Are there any plans to adjust this resolution to adapt for the new monitor standard of wide screen?
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Category:
Scoring Manual > Technical Specifications
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Last Updated:
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6/1/2010 |
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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.
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R. 25. What is considered "pre-event" baseline pulse oximetry for scoring a hypopnea? Can I choose a baseline pulse oximetry reading during stable, non-eventful N sleep and use this "baseline number" as my "pre-event" baseline number during the remainder of the recording OR is there a standard duration of time prior to or after a hypopnea which is used to determine a patient's "pre-event" baseline?
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Category:
Scoring Manual > Respiratory Rules
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Last Updated:
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12/8/2009 |
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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.
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A.2. There is a disagreement between the scoring of arousals in wake and the scoring of respiratory events in wake. The scoring of arousals allows for one arousal every 13 seconds, resulting in a possible maximum arousal index of 276.9 per hour. Use of this rule introduces the statistical possibility for reporting of an irrational index. The AASM should reconsider its position with regard to scoring arousals in wake epochs, change the guidelines for scoring wake in the concurrence with "scorable" arousals or else change the definiton of C2 from the reported arousals per hour of sleep to arousals per hour in bed (Ar/hrTIB).
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Category:
Scoring Manual > Arousals
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Last Updated:
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12/8/2009 |
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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.
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T.5. The blanket technical requirement for all channels is 12-bit which makes sense for most channels, and especially the high frequency channels. But it doesn’t make sense for the Body Position channel. Eight bit resolution provides up to 256 values for a signal that generally has 5 total positions, so 12 bit is very much overkill with over 4,000 possible values. I would ask for reconsideration in the standard requirement specific to Body Position.
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Category:
Scoring Manual > Technical Specifications
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Last Updated:
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10/2/2009 |
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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.
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P.R.2. In reviewing the respiratory rules for hypopneas in children, the only alternative sensor for
detection of airflow for identification of a hypopnea is an oronasal thermal sensor.
The option of using an uncalibrated or calibrated inductance plethysmography sensor when
the nasal pressure device is not functioning is listed as an alternative option in the adult
respiratory rules. It is NOT listed as an alternative for children. Is this an oversight?
It's important to have the option to use an inductance "sum" sensor in children. Directly
measured airflow signals placed under the nose like nasal pressure (or even oronasal airflow)
are frequently absent or poor quality because of mouth breathing or patient intolerance.
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Category:
Scoring Manual > Pediatric Respiratory
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Last Updated:
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9/15/2009 |
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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
children.
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P.R.1. Is ETCO2 an acceptable air flow signal? Can it replace one or both of the others?
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Category:
Scoring Manual > Pediatric Respiratory
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Last Updated:
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9/15/2009 |
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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.
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R.24. We are puzzled by a hypopnea rule on page 46. It is 'note #2' under '4.Hypopnea Rules' which
stages that "classification of hypopneas as obstructive, central or mixed should not be
performed without a quantitative assessment of ventilatory effort (esophageal manometry,
calibrated inductance plethysmography, or diaphragmatic/intercostal EMG)."
The questions are as follows:
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Category:
Scoring Manual > Respiratory Rules
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Last Updated:
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9/15/2009 |
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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.
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R.23. My question is about respiratory sighs during sleep. Was this normal, physiological event ever
addressed during the creation of the new respiratory scoring rules? I would like to know how
the committee feels about scoring or not scoring, single or multiple sighs during sleep. There
is no mention of sighing at all in the new handbook.
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Category:
Scoring Manual > Respiratory Rules
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Last Updated:
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9/15/2009 |
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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
defined.
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R.22.
I attended the June 8th APSS session, “Implementing the AASM Scoring Rules” in 2008. It was
very informative and well presented, but I and another audience member had a question
about the use of the word contiguous during the respiratory scoring lectures (and also in a
FAQ answer) that seemed to change the meaning of a rule in the 2007 scoring manual. The
FAQ question is R.11. The answer states that "if the amplitude criteria are met during any
contiguous 9 sec of an event that lasts 10 sec or longer then the event should be scored…"
The word contiguous was used on 6/8/08 by presenters as well. In the 2007 scoring manual,
the word contiguous is not used as far as I could see. When the word contiguous is used, it
seems to means that apneas and hypopneas need only be 9 seconds in duration thus
changing the duration criteria of the definitions. This is because the 1 second that does not
meet amplitude criteria must be at the beginning or end of the event if the event is 10
seconds in duration. When the specification of being contiguous is not used it means that
during a 10 second apnea or hypopnea there may be 1 second at any point during the event
that does not meet amplitude criteria so the event is still defined as being 10 seconds long.
We took the use of the word contiguous as meaning that now apnea and hypopneas are
defined as being 9 seconds long since the first or last second of a 10 second event need not
meet amplitude reduction criteria (even though I don’t see the word contiguous in the 2007
scoring manual itself.) Also‐ In reading both R.10 and R.11, I’m thinking that in the context of
the example of the 17 second event, I understand the recommendation to look for 9
contiguous seconds within that event. However for a 10 second event the manual does not
specify that the 9 seconds be contiguous and this is what seems to change the event duration
criteria to 9 seconds.
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Category:
Scoring Manual > Respiratory Rules
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Last Updated:
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9/15/2009 |
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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.
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R.20.
In the special article “Clinical Guidelines for the Use of Unattended Portable Monitors in the
Diagnosis of Obstructive Sleep Apnea” published in the December, 2007 issue of JCSM, it is
recommended in Section 2.2 that both nasal pressure transducers and thermistors be used to
detect apneas. However, the article details the limitations of both of these methods, namely
the inability to detect oral flow (nasal pressure devices) and the non‐linear relation to airflow
and overestimation of ventilation (thermistors). The guidelines also state in the next section
(2.3) that respiratory inductance plethysmography, when appropriately calibrated, provides
an accurate measure of tidal volume. Since (Tidal Volume) = (Flow) x (Time), might a
measurement of tidal volume calculated using calibrated RIP be an acceptable alternative for
measuring flow? How might we initiate some dialog with AASM regarding this alternative?
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Category:
Scoring Manual > Respiratory Rules
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Last Updated:
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9/15/2009 |
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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”).
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M.5.
I discovered an issue for clarification in the scoring manual on p 41 concerning note 1 in the
PLM section. It states “An LM should not be scored if it occurs during a period from 0.5
seconds preceding and apnea or hypopnea to 0.5 seconds following an apnea or hypopnea.”
I think the intent was to say that the LM should not be scored during a period from 0.5
seconds preceding to 0.5 seconds following the termination of an apnea or hypopnea. As
stated, it indicates that no PLMs would be scored at all during a respiratory event.
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Category:
Scoring Manual > Movement
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9/15/2009 |
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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.
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V.11. R ends with a transition to W (p. 28), but doesn’t end if there is an arousal that is not
followed by slow eye movements. What if the arousal consists of a shift to alpha rhythm that
lasts 3 seconds? Would that be a transition to W? How about 5 seconds? Or do you need an
epoch of W to end R?
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Category:
Scoring Manual > Visual Rules
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9/15/2009 |
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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.
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V.10. The rule for N3 sleep (p. 27) says that you should score N3 whenever 20% of the epoch
consists of slow wave activity. This makes sense if the rest of the epoch is low amplitude
mixed frequency EEG, but what if there is an awakening after 6 seconds of dense slow wave
activity and alpha rhythm activity for the remainder of the epoch? Would this still be N3?
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Category:
Scoring Manual > Visual Rules
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9/15/2009 |
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No, this would be scored as W using IV.2.B.3.
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G.1. I see that the STANDARDS FOR ACCREDITATION state that we are to use the recommended
AASM guidelines, when available. Does this mean if our medical director chooses for us to
use an alternative rule that our accreditation is at risk?
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Category:
Scoring Manual > General
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9/15/2009 |
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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."
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G.2. When/where will the committee’s response to this (and other) questions be published?
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9/15/2009 |
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The Steering Committee provides responses to specific questions sent to the national office by
e‐mail to rrosenberg@aasmnet.org such as the one you are reading. Questions of more general
interest have been posted over the past year at this website.
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G.3. Is the Steering Committee you referred to the Standards of Practice Committee or is this an
extension of the Task Force for Unattended Testing?
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Scoring Manual > General
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9/15/2009 |
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T.1. I have just bought NEW PSG EQUIPMENT. Do I need to change my equipment again to
become compliant with the technical specifications on pages 19‐21?
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Category:
Scoring Manual > Technical Specifications
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9/15/2009 |
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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:
- Be compliant with the new rules for EEG, EOG, EMG and respiratory signals, including using both thermal and nasal pressure sensors to record respiratory events (pages 45 and 48)
- Have modified your reporting software to reflect the parameters to be reported (pages 17‐18) and the new sleep stage terminology (page 24)
- Be scoring stages and events according to the new rules
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T.2. Is there a requirement for CONTINUOUS AUDIO RECORDING during polysomnography under
the new guidelines?
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Category:
Scoring Manual > Technical Specifications
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9/15/2009 |
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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.
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