From Wikipedia:

In the context of diagnosis and treatment of sleep disorders, a hypopnea is not considered to be clinically significant unless there is a 30% (or greater) reduction in flow lasting for 10 seconds or longer and an associated 4% (or greater) desaturation in the person's O2 levels, or if it results in arousal or fragmentation of sleep.

Three Questions:

1) Is this the best definition?

2) Is a drop in O2 from 90% to 86% a 4% desaturation or is it a 3.6% desaturation?

3) How is a 30% drop in flow rate identified?

Yes

For a sleep lab it's 4%. We don't have equipment that sensitive. Really only arterial blood gas is accurate in getting SPo2 values, but a needle plunged into the arm would FOR SURE wake people up.

Nadir to nadir for length of the event, and a 30% decrease in the airflow sin wave that is measured in microvolts. Sounds complicated maybe...but it's not.

_________________
TheLankyLefty
http://www.youtube.com/TheLankyLefty27
Consider being our Patreon: https://www.patreon.com/FreeCPAPAdvice
Shop Amazon and help out FreeCPAPAdvice by using this link: http://amzn.to/2dY19oA
Information on FreeCPAPAdvice.com should not be considered medical advice. Seek your physicians advice before seeking treatment for medical conditions. Information posted on the FreeCPAPAdvice.com website and forum is opinion and not statements of fact.

Great definition

Hi Jason! It's Niall from Ireland. I hope you're keeping well. We have very few sleep centres over here that carry out PSG; however most centres perform limited polysomnography (nasal cannula, oximeter, chest & abdomen belts). How is an arousal accurately determined in this test? Does a significant change in the body belts suggest an arousal?

Limited tests are basically attended Type 3 home sleep tests. Arousals aren't accurately determined other than visually by the night technologist....but without EEG even this isn't completely accurate.

It can be a clue to the whole puzzle, but it still isn't enough information to accurately predict arousals with certainty.

_________________
TheLankyLefty
http://www.youtube.com/TheLankyLefty27
Consider being our Patreon: https://www.patreon.com/FreeCPAPAdvice
Shop Amazon and help out FreeCPAPAdvice by using this link: http://amzn.to/2dY19oA
Information on FreeCPAPAdvice.com should not be considered medical advice. Seek your physicians advice before seeking treatment for medical conditions. Information posted on the FreeCPAPAdvice.com website and forum is opinion and not statements of fact.

Thanks! Great YouTube videos. Keep up the amazing work.

Wiki editors must have superior writing skills- they always have the best definitions.