What is the average apnea hypopnea index

How is it calculated? Why does it change? To break it down, the term apnea means that you stop breathing for at least 10 seconds. Hypopnea is when you have a partial blockage of your airway so your breath is more shallow than normal. When you look at your apnea-hypopnea index, it tells you how many apneas and hypopneas you have per hour while you sleep and gives you an average.

A woman with sleep apnea messaged us after she noticed that over the previous week her AHI had fluctuated between 1. Measure content performance. Develop and improve products. List of Partners vendors. Continuous positive airway pressure CPAP is a breathing device prescribed to treat sleep apnea. The purpose of a CPAP is to improve breathing at night. But how do you know if the treatment is working well enough?

The apnea-hypopnea index AHI is a helpful way to measure how severe your sleep apnea is. It can also help you see how well your body is responding to treatment. It also answers questions such as these:. First, it is important to understand what the apnea-hypopnea index AHI reading means. The AHI is the average number of times your body has an apnea or a hypopnea event in one hour of sleep. Apnea is when your breathing pauses while you sleep. The pause can be caused by your tongue or the soft palate at the back of your mouth closing off the airway.

Each time apnea happens, it can cause you to wake up briefly. It can also cause the amount of oxygen in your blood to drop. When air stops flowing through your nose and mouth, you are having an apnea event, even if your chest and abdomen are moving as you try to breathe.

Hypopnea refers to a period of shallow breathing. It is considered less severe than apnea. If you take shallow breaths, you may have hypoventilation, which means you're not taking in quite enough air to meet your body's oxygen needs. Hypoventilation can also happen if you have an unusually low respiratory rate.

Your respiratory rate is the number of breaths you take in one minute. Some researchers argue that hypopnea and apnea are almost identical events. To qualify as an apnea or hypopnea event, the change in breathing must last at least 10 seconds. The AHI counts both types of breathing disturbance. The number is used to rate the severity of sleep apnea. It is also used to measure how well treatments such as CPAP machines are working. AHI is the average number of times your airflow is reduced or your breathing stops during one hour of sleeping.

It can be used to rate the severity of sleep apnea and measure how well treatment is working. The first place you may see an AHI is on a sleep study report. To diagnose sleep apnea, specialists use a sleep study, also called a polysomnogram. These studies usually take place in a sleep disorder center. Sometimes sleep apnea is diagnosed using home sleep apnea testing.

These studies track your breathing patterns through the night. They rely on sensors such as these:. The sensors show how many times you stop breathing or breathe shallowly during the night.

They also can detect changes in the oxygen levels in your blood. Some sleep facilities use other measures than the AHI. The respiratory-disturbance index RDI counts apnea and hypopnea events plus less severe breathing interruptions. This oxygen drop may raise your risk of long-term cardiovascular problems such as high blood pressure, heart attack, and heart failure.

The oxygen drop could also lead to stroke, dementia, or other neurological problems. If your sleep study does not contain these more specific measures, it's nothing to worry about. Your breathing can change from one night to the next. For that reason, it probably isn't useful to try to reach a specific daily number. Sleep apnea may be worsened by:. Because your AHI can be affected by these factors, it may be best to calculate your average results over 30 to 90 days.

The optimal goal for you may depend on how severe your condition is. Your goal could also depend on what's causing your breathing problem. An ideal AHI is fewer than five events per hour. Corresponding author. Corresponding author MD. Received Feb 11; Accepted Apr 4. This is an open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3. This article has been cited by other articles in PMC. References 1.

American Academy of Sleep Medicine. Obstructive sleep Apnea. Illinois: American Academy of Sleep Medicine Updates on definition, consequences, and management of obstructive sleep apnea. Mayo Clin Proc. Severity of depression and anxiety in obstructive sleep apnea syndrome. Eur Arch Otorhinolaryngol.