Apnea Hypopnea Index – What is the Apnea-Hypopnea Index and how can it help me sleep better?

apnea hypopnea index

Apnea Hypopnea Index

The Apnea Hypopnea Index (AHI), similar though different from Respiratory Disturbance Index (or RDI), is a measuring standard used to assess the number of times they stop breathing (apnea) as well as the number of times their sleep is disrupted (hypopnea) during rest hours. The term “apnea” comes from the Greek prefix “a” (“without”) and “pneein” (“to breathe”). The apnea measured in the Apnea-Hypopnea Index, then, are moments in time that the person sleeps “without breathing.” Usually, the individual’s breathing stops around ten seconds or longer. “Hypopnea” comes from the Greek words “hypo” (“below”) and “pneein” (breathing). The term hypopnea refers to those whose breathing is “below breathing” during the night (indicating moments of sleep disturbance).

 

Hypopnea is different from apnea in that hypopnea concerns shallow breathing while apnea concerns the absence of breathing. A person with sleep apnea could potentially die if their breathing stops for an unusual amount of time during the night. This can occur because of the cutoff of oxygen to the lungs and throat. The AHI is conducted for patients who possess all the symptoms indicative of sleep apnea.

 

The Apnea-Hypopnea Index normal range runs somewhere between 0-5 breath cessation events a night. The Apnea-Hypopnea Index scale, however, provides guidelines by which an individual can measure whether he or she has sleep apnea or sleep hypopnea:

 

  • Mild (5-15 apnea and hypopnea events for each hour of sleep)
  • Moderate (15-30 events per sleep hour)
  • Severe (30+ events per hour of sleep)

 

These guidelines are important, but they do not provide details on how to measure breathing against the scale. So how exactly does arrive at an Apnea-Hypopnea Index calculation? One arrives at an AHI calculation by doing the following:

 

  • Add together the apnea events (no breathing) and hypopnea events (shallow breathing)
  • Find the total time (minutes) you slept. To do this, multiply the rest hours by 60 minutes/hour.
  • Divided the total number of sleep events (apnea and hypopnea) by the rest time (minutes).

 

For example, let’s say you have 35 apnea events and 35 hypopnea events during the night. To find your Apnea-Hypopnea Index (AHI), you would combine the two:

 

  • 35 + 35 = 70

 

Next, you would find the total time you slept. If you slept 8 hours, you would multiply 8 by 60:

 

* 8 x 60 = 480 minutes

 

Then, divide the number of sleep events by the total minutes you slept:

 

  • 70/480 = 0.1458333333

 

Last but not least, multiply the decimal result by 60:

 

  • 0.1458333333 x 60 = 8.749999998

 

This individual had 70 events during 8 hours of sleep, for an AHI of 8.75, or 9. “9” fits the mild category, since the mild category is classified as anywhere from 5-15 sleeping events.

 

The AHI can be calculated for someone who has very extreme case. If an individual has 75 apnea and 75 hypopnea events, you can calculate their AHI index by the following:

 

First, add the apnea and hypopnea events together:

 

  • 75 + 75 = 150 events

 

Next, determine the total time the individual slept:
* 5 hours = 5 x 60 = 300 minutes

 

Then you would take the number of events and sleep minutes and divide them:

 

  • 150/300 = 0.5

 

Lastly, take the decimal and multiply by 60:

 

  • 0.5 x 60 = 30

 

The individual in question has an AHI of 30, which classifies him or her as a borderline (if not baseline) severe apnea-hypopnea patient, since the moderate classification goes up to 30 and the severe classification is 30 and above. This individual certainly needs sleep treatment so as to avoid death by sleep apnea. This is not the most severe case, however: since the severe index can go above 30, an individual can have an AHI index of “42” and be in a worse state than the individual who registers “30” on the AHI.

 

Sleep apnea and sleep hypopnea have both been discussed; how to calculate the AHI index has been discussed. However, what about the significance of the numbers? The AHI numbers signify an underlying medical condition. If someone registers a “30” on the AHI scale, for example, he or she most likely has some physical symptoms that they have largely ignored, perhaps unbeknownst to them. Apnea symptoms are the following:

 

  • Snoring
  • Memory Problems
  • Restless Sleep
  • Headaches
  • Personality Changes

 

The person with sleep apnea snores frequently, and loudly. Next, the sleep apnea patient suffers from memory problems. He or she lacks memory recall and concentration on easy tasks. Next, sleep apnea patients suffer from restless sleep. Often, they will toss and turn in their sleep, several times a night to find a comfortable place to rest—though they do not find it. Headaches are common: sleep apnea patients experience headaches either during their sleep or after they wake up in the morning. Lastly, sleep apnea patients undergo personality changes. They may become more irritable suddenly, or less sociable than normal, etc. Watch for major personality changes, as this may be a sign that the person is not getting enough rest.

 

The Apnea Hypopnea Index (AHI) is a key used by doctors to assess the level of apnea-hypopnea sleeping disorder a person has. Apneas are the number of times a person stops breathing during the rest, while hypopneas are the number of times a person has shallow breathing while sleeping. If you calculate your AHI index and find that you have a rather moderate to a severe case, you should talk with your doctor right away to see what treatment options are available. You never know: assessing your AHI index just might save your life.