Apnea–hypopnea index

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Apnea–hypopnea index

The Apnea–Hypopnea Index or Apnoea–Hypopnoea Index (AHI) is an index used to indicate the severity of sleep apnea. It is represented by the number of apnea and hypopnea events per hour of sleep. Apnea is the complete absence of airflow through your nose and mouth. Hypoapnea is a partial collapse of your airway, limiting breathing. Apneas (pauses in breathing) must last for at least 10 seconds and be associated with a decrease in blood oxygenation to be considered. Combining AHI and oxygen desaturation gives an overall sleep apnea severity score that evaluates both the number of sleep breathing disruptions and the degree of oxygen desaturation (low oxygen level in the blood) during said disruptions.

The AHI is calculated by dividing the number of apnea events by the number of hours of sleep. The AHI values for adults are categorized as:[1][2]

  • Normal: AHI<5
  • Mild sleep apnea: 5≤AHI<15
  • Moderate sleep apnea: 15≤AHI<30
  • Severe sleep apnea: AHI≥30

For children, because of their different physiology, an AHI in excess of 1 is considered abnormal. Underage pediatric patients presenting with AHI of 2 or greater will often be referred for treatment.[3]

See also[edit]


  1. ^ "Understanding the Results: Sleep Apnea". med.harvard.edu. Harvard Medical School, Harvard University. Retrieved 5 September 2014.
  2. ^ Ruehland WR, Rochford PD, O'Donoghue FJ, Pierce RJ, Singh P, Thornton AT (1 February 2009). "The new AASM criteria for scoring hypopneas: impact on the apnea hypopnea index". Sleep. 32 (2): 150–7. doi:10.1093/sleep/32.2.150. PMC 2635578. PMID 19238801.
  3. ^ Chan, James; Edman, Jennifer C.; Koltai, Peter J. (March 2004). "Obstructive Sleep Apnea in Children". American Family Physician. 69 (5). American Academy of Family Physicians: 1147–1155. PMID 15023015. Retrieved 11 October 2016.