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. The apneas (pauses in breathing) must last for at least 10 seconds and be associated with a decrease in blood oxygenation. Combining AHI and oxygen desaturation gives an overall sleep apnea severity score that evaluates both the number of sleep disruptions and the degree of oxygen desaturation (low oxygen level in the blood).

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

• Normal: 0-4
• Mild sleep apnea: 5-14
• Moderate sleep apnea: 15-29
• Severe sleep apnea: 30 or more

Risks associated with a high AHI

Research shows that individuals suffering from obstructive sleep apnea are at a higher risk of other health comorbidities, including:

• Acute myocardial infarction/heart attack (obstructive sleep apnea presents in 70% of heart attack patients with AHI ≥5 and 52% of heart attack patients with AHI ≥10)^[3]
• Stroke (in patients with AHI ≥30 macroangiopathic etiology of stroke were significantly higher than in patients with AHI <10)^[4]

See also

• Obstructive sleep apnea
• Respiratory disturbance index
• Oxygen saturation (medicine)

References

1. "Understanding the Results: Sleep Apnea". 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. PMC 2635578. PMID 19238801.
3. Kuniyoshi; et al. (July 2008). "Day–Night Variation of Acute Myocardial Infarction in Obstructive Sleep Apnea". Journal of the American College of Cardiology 52 (5): 343–346. doi:10.1016/j.jacc.2008.04.027.
4. Claudio L. Bassetti, Milena Milanova, Matthias Gugger (6 March 2006). "Sleep-Disordered Breathing and Acute Ischemic Stroke: Diagnosis, Risk Factors, Treatment, Evolution, and Long-Term Clinical Outcome". Stroke 37: 967–972. doi:10.1161/01.STR.0000208215.49243.c3.