What is AHI?

AHI stands for apnea-hypopnea index. AHI is a scale that tells whether or not you have sleep apnea and, if so, how severe it is.

Sleep apnea is when you stop breathing for 10 seconds or more while you’re asleep, whereas hypopnea, is a partial loss of breath for 10 seconds or longer. Normal sleep involves air passing through and going directly down to the lungs. With an obstructed airway, the structures in the back of the throat (the tongue, the tonsils, and/or adenoids) occlude the airway due to an inadequate motor tone of the tongue and/or airway dilator muscles, and thus, prevent the air from passing. This creates repetitive episodes of obstruction of the upper airway causing a loss of breath and oxygen, anywhere from 10 to 30 seconds or longer. When this occurs, blood oxygen levels drop, and heart rate and blood pressure rise. The brain ultimately sends a distress signal that partially or fully wakes the person and alerts the body to breathe, causing the patient to gasp for air.

What do the numbers in the AHI mean?
The AHI is the number of times you have apnea or hypopnea during one night, divided by the hours of sleep.

Normal sleep: An AHI of fewer than five episodes on average, per hour
Mild sleep apnea: An AHI of 5-14 episodes per hour
Moderate sleep apnea: An AHI of 15-29 episodes per hour
Severe sleep apnea: An AHI of 30+ episodes per hour

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