What are the AASM scoring rules for polysomnography (PSG)?

Updated: Apr 29, 2020
  • Author: Carmel Armon, MD, MSc, MHS; Chief Editor: Arlen D Meyers, MD, MBA  more...
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In 2015, the AASM updated scoring rules, making changes to scoring of apneas, hypopneas, Cheyne Stokes respiration, and hypoventilation.

The event duration starts at the nadir preceding the first breath that is clearly reduced to the beginning of the first breath that approximates the baseline breathing amplitude. Events terminate if there is a clear and sustained increase in breathing or if there is a desaturation, when there is a re-saturation of at least 2%.

Polysomnography reports should report an apnea/hypopnea index (AHI), which, for an in-lab study, is the number of apneas and hypopneas per hour of sleep. For portable studies, the AHI is the number of apneas and hypopneas per hour of test. It is important to know what criteria was used for the events as there have been many changes to the scoring criteria for hypopneas, which may have led patients who were scored with desaturation criteria only to have significantly underestimated sleep apnea. In general, an AHI > 5 is considered significant sleep apnea. Some polysomnography report respiratory disturbance index (RDI), which is typically the number of apneas plus hypopneas plus respiratory-related arousals.

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