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AHI ? - Printable Version

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AHI ? - John521 - 08-17-2020

My AHI is .6   does this tell me that my machine and pressure are working correctly or is there more info that i need to look at?  my events are at 1.2 per hour
i don't feel that my pressure is what is used to be when i first started using a machine 10 years ago but i am using an auto adjust machine?

any thoughts


RE: AHI ? - mesenteria - 08-17-2020

The industry and insurers consider anything below 5.0 to be 'treated'.  Most of us do much better with some tinkering and learning, often below 2.0.  You are (probably) in the 85 %ile or better with a low AHI like yours, so you're doing very well, despite no pressure adjustments.  Note that this assumes your machine is accurately measuring and reflecting your real AHI, and isn't somehow defective.  But, if you sleep well, feel rested, and don't seem to be deteriorating unduly, you're probably in good hands.

RE: AHI ? - sptrout - 08-17-2020

Your stated AHI of .6 with 1.2 events per hour do not compute. AHI is calculated by dividing the total number of "apnea" events all night by the hours of "sleep" including the remaining fraction of an hour, if any. Actually, "sleep" is a bogus number unless you actually fall asleep the minute you hit the "on" switch and turn it "off" the moment you wake up. Neither is at all likely since the machine can never tell if a user is actually asleep or awake. A more typical number being in the range of 20-60 minutes to fall asleep, and waking-up, well you know that number (remembering when a person falls asleep is more difficult). Always look at any events that may be recorded while you were asleep according to the machine when you know that you were really awake even in the middle of the night (watch for bogus "centrals" since many people hold their breath when turning over for example). If your brand of APAP only shows "events per hour" then that is a useless number IMO. You need to know the number of events all night and use software that can show you where the events are happening (the events may be scattered randomly all night, or clustered all within a hour or two).

I dug back into my history to find a really bad night for me so I could find something close to an AHI of .6. One night that I found I had an AHI of .66 with 5 events all night and a total of 7.35 hours of sleep. If you divide 5 events by 7.51 the results are .66 which was the AHI for the night. 

In your case (using some unknown, by me, made-up numbers): 1.2 events per hour X 8 hours of assumed sleep = an AHI of 1.2 (number of total events divided by the hours of sleep). For simplification, I used exactly 8 hours, which is not typical but would normally be a number of hours plus some additional fraction thereof. 

I also noticed in your equipment area that you listed your pressure at 4-20. Is that what you are actually using, or is your machine set to something more typical of say 7-15? New APAP machines come set to wide open (4-20), but are usually adjusted by the user or doctor to a more reasonable number. If your machine is really set at 4-20 then you will experience some low pressure levels especially at startup. This could be the reason for your perceived low pressure. It may be starting at 4 and staying there for a prolonged period of time.

All that said, if your AHI is .6 or 1.2, then either is considered treated as "mesenteria" mentioned. I hope that I did not get to deep into the weeds, you may know all of what I have written but many newer users do not understand how AHI is calculated.

RE: AHI ? - Gideon - 08-17-2020

All I can say is that you have mild sleep apnea post your OsCAR charts and we can tell you more.