Apnea–hypopnea index
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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. Hypopnea 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]
The Apnea-Hypopnea Index has been criticized for being too simplistic to accurately rate apnea and hypopnea events for their severity.[4][5]
In one study, mean apnea-hypopnea duration and not AHI was found to be associated with worse hypertension.[6]
One long apnea event is clearly worse than the same period broken up into shorter multiple events, with breathing between events, yet it would have the lower AHI.
See also
[edit]
References
[edit]- ^ "Understanding the Results: Sleep Apnea". med.harvard.edu. Harvard Medical School, Harvard University. Retrieved 5 September 2014.
- ^ 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.
- ^ 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.
- ^ Borsini, Eduado; Nogueira, Facundo; Nigro, Carlos (Jan–Feb 2018). "Apnea-hypopnea index in sleep studies and the risk of over-simplification". Sleep Science. 11 (1): 45–48. doi:10.5935/1984-0063.20180010. PMC 5916576. PMID 29796201.
- ^ Punjabi, Naresh M. (Jan 2016). "Is the Apnea-Hypopnea Index the Best Way to Quantify the Severity of Sleep-disordered Breathing? No". Chest Journal. 149 (1): 16–19. doi:10.1378/chest.14-2261. PMID 26182150.
- ^ Wu, Hao; Zhan, Xiaojun; Zhao, Mengneng; Wei, Yongxiang (Dec 2016). "Mean apnea–hypopnea duration (but not apnea–hypopnea index) is associated with worse hypertension in patients with obstructive sleep apnea". Medicine. 95 (48): e5493. doi:10.1097/MD.0000000000005493. PMC 5134767. PMID 27902610.
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