From the AHI rating chart here, we see that an index less that 5 is considered normal. For an Apnea-Hypopnea Index (or AHI) from 5 to 15 denotes mild sleep apnea. Fifteen to 30 is moderate, while a greater than 30 AHI is considered severe.
  • AHI = sum of the number of apneas (pauses in breathing) plus the number of hypopneas (periods of shallow breathing) occurring, on average, each hour.
  • Apneas and hypopneas, collectively called events, must last at least 10 seconds to count as events.
  • The AHI is calculated by dividing the number of events by the number of hours of sleep.
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