The Apnea–Hypopnea index, also known as the Apnoea–Hypopnoea Index (AHI), in an index used to measure the severity of sleep apnea. It is represented by the number of apnea and hypopnea events per hour of sleep. The apnea must be at least 10 seconds long and cause a decrease in blood-oxygenation. An overall sleep apnea severity score can be found by combining AHI and oxygen desaturation. This score evaluates both the number of sleep disruptions and the degree of oxygen desaturation.
The AHI values for adults are categorized as:
- Normal: AHI<5
- Mild sleep apnea: 5≤AHI<15
- Moderate sleep apnea: 15≤AHI<30
- Severe sleep apnea: AHI≥30