Apnea and Hypopnea Index – So just how bad is it?

By Clinton Marquardt - Sleep & Fatigue Specialist

January 2, 2007

sleep apnea, sleep tests, snoring

So just how bad is it?
Calculating an Apnea and Hypopnea Index

Ever wonder how the sleep doctors decide how bad your breathing problem is? It’s actually an easy process that depends on how many times you stop breathing altogether (apneas) and how many times your breathing becomes restricted (hypopneas).

The apneas and hypopneas across the night are counted and then divided by the hours of sleep. This process is normally completed in a sleep lab and gives the sleep doctors an Apnea & Hypopnea Index. Here’s the formula they use:

A + H Index = # of Apneas + # of Hypopneas divided by the Total Sleep Time (mins.) multiplied by 60 (minutes/hour)

An A+H Index of five or more is clinically significant and usually requires treatment. However, it is not uncommon to have an index over 50. To determine what, if any, treatment is needed, the sleep doctors consider how well the person functions and how they feel during the day without treatment. For example, if one person has an A+H Index of 6.4 and feels fine, then perhaps treatment is unnecessary. On the other hand, a person with an A+H Index of 7.4 might feel very sleepy during the day and treatment may be required.

Keep in mind that apneas and hypopneas are often lumped together and collectively referred to as Respiratory Disturbances. For this reason the A+H Index is also called a Respiratory Disturbance Index or RDI.


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