apnea-hypopnea index
Pronunciation: AP-nee-ah hy-pop-NEE-ah IN-deks
Also written as: AHI — apnea-hypopnea index
Measurement of sleep-disordered breathing severity, calculated as the number of apneas and hypopneas per hour of sleep.
Full Definition
The apnea-hypopnea index (AHI) is the primary metric used to diagnose and classify the severity of obstructive sleep apnea. An apnea is defined as a complete cessation of airflow for at least 10 seconds, while a hypopnea is a partial reduction in airflow with associated oxygen desaturation or arousal. AHI values are categorized as normal (< 5), mild sleep apnea (5-14), moderate sleep apnea (15-29), and severe sleep apnea (≥ 30). The AHI is calculated by dividing the total number of respiratory events by the total sleep time in hours.
Usage
Usage note: Hyphenate when used as a compound modifier. Commonly abbreviated as AHI.
In Context
- "The apnea-hypopnea index of 32 events per hour indicated severe obstructive sleep apnea." — Sleep study interpretation
- "Treatment with CPAP therapy reduced the patient's apnea-hypopnea index from 28 to 3." — Follow-up sleep study report