Question: If hypopneas are being scored according to Rule D.1.A., is a ≥3% oxygen desaturation required in addition to an associated arousal?
Answer: Rule D.1.A. in The AASM Manual for the Scoring of Sleep and Associated Events, Version 2.5, states the following:
Score a respiratory event as hypopnea if ALL of the following criteria are met:
a. The peak signal excursions drop by >30% of pre-event baseline using nasal pressure (diagnostic study), PAP derived flow (titration study), or an alternative hypopnea sensor (diagnostic study).
b. The duration of the >30% drop in signal excursion is >10 seconds.
c. There is a >3% oxygen desaturation from pre-event baseline or the event is associated with an arousal.
As stated above, if criteria a and b are met, then a hypopnea is scored if there is at least a ≥3% oxygen desaturation from the pre-event baseline OR the event is associated with an arousal. Thus, the event could be associated with only a ≥3% oxygen desaturation, only an arousal, or both.
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