AHI vs Hours Slept?

[DoriC]

Here's my question if I can explain it. How do I interpret a higher AHI(2.3-2.7)) than his usual((0.5-1.5) if my husband has slept 10hrs as opposed to 8hrs. I'm thinking that if I threw away the events that happened in the last 2 hrs his AHI would be in the lower range. Is that correct ?

[rjjayrt]

I don't think so. Your AHI is # of apneas and hypopneas divided by total hours slept. The slight increase in his AHI could be a result of his sleeping better (10 hours vice 8 hours) he may have been in a deeper sleep which caused a few more arousals. In any case an AHI under 3 is very good assuming he's feeling good. Small changes in AHI from night to night is fairly common, I wouldn't give it much thought as long as he's feeling good. Now larger increases such as 2.5 to 8 or nine might be more worrisome.

[DoriC]

Good to hear that, thanks.

[Julie]

I actually might interpret his sleeping longer to not having slept as well (hence the higher AHI) for whatever reason that night, but as long as he gets back to his normal schedule, I wouldn't worry at all.

[azhosehead]

If your husband is clocking 8-10 hrs of sleep with the AHI numbers that you are saying, he is doing great! If he wakes up feeling rested and refreshed that is the main thing to judge the quality of sleep by. I consider an AHI of 4 or less to be good (barring mask leaks, etc.). I like to take the AHI number and divide it by hours of sleep. If that percentage factor remains the same or lower, I wouldn't worry about the AHI. I think more sleep and quality sleep is the key to good sleep apnea treatment.

I had a sleep study done just under a year ago and by the end of the session I was having no events at all (with the right pressure) in the lab. I slept at home the next night and looked the data on the machine and it showed AHI's. I asked doctor how come in the lab in didn't have AHI's but my machine records AHI's. The answer was in a nutshell is that a sleep study lab has much more sophisticated equipment and gets data from multiple sources (breathing, oxygenation, brain activity, heart rate, etc.) whereas the CPAP machines have software that interprets what it finds based on the breathing interaction in the mask alone. The doc did concede that if the CPAP machine records fewer AHI's that is a good thing. My doc gave me the figure of 4 AHI's per night as a good guideline.

The numbers can be interesting and it is easy to get caught up in them. If your husband sleeps the 10 hours a night and feels like crap when he gets up and is tired all day, perhaps he needs to get a sleep study to find out what is making him feel so lousy. If he is rested, energetic, functional and doesn't experience excessive sleepiness during the day, that is the goal we are all hoping to achieve from CPAP therapy.

[DoriC]

AZ, thanks for that analysis. I do tend to somewhat overreact to the numbers since I'm not always getting much input from my husband as to how the night went, but I'm finally getting things into perspective and now if there are occasional blips I watch for trends in how he's looking and feeling. In another thread I posted about, I definitely saw changes in his energy levels that correlated with elevated AHIs in the 3.1 range. It took a few days but he finally admitted that he had been feeling cold during those nights and had not slept well. So at least I know the machine is doing it's job pretty accurately and telling me what I need to know.

[JohnBFisher]

Here's my question if I can explain it. How do I interpret a higher AHI(2.3-2.7)) than his usual((0.5-1.5) if my husband has slept 10hrs as opposed to 8hrs. I'm thinking that if I threw away the events that happened in the last 2 hrs his AHI would be in the lower range. Is that correct ?

DoriC, as others noted, even the increased numbers are pretty good. But it's quite likely that with 10 hours your husband spent more time in REM and deep sleep where people tend to have more apnea events. As the body "disenages" muscle activity during REM sleep, it often causes the airway to obstruct more readily. At least that's the norm. But if he still feels well, be glad he could enjoy the sleep.

[DoriC]

Yes John, I'm not really concerned about the higher AHI, still good numbers,(can't believe I really said that) , and I do notice from the data and my own observations that he was probably in REM sleep during those last hours which is usually when he has his events anyway.. I was just curious and always wanting to understand everything.

[wjp]

I would not just throw out the last two hours, but it is also possible he was not really sleeping.

I find the mornings where I stay in bed trying to get a little extra sleep ( but don't ) my numbers are way up. When I look a the detail data I see big clusters of Hypopneas during the times when I know I was awake.

When you are awake your breathing is less regular, so the machine may interpret it as a Hypopnea when it really is not. The measurement algorithms the machines use are pretty amazing, but not perfect.

I'd just be excited about having 10 hours of something like sleep regarless of the numbers.

[Mac33]

I got a RESMED elite II about three weeks ago after using a resporonics m series for three months. I didn't know I could check my numbers without the software so till this morning. Anyway my AHI mwas 16 for 8 hours of sleep. I guess that's good from reading the posts here.

[DoriC]

The sleep professionals consider AHI=<5.0 or less good therapy. Did you mean AHI= 1.6? Yes, it could be possible he wasn't sleeping deeply those last hours and was sighing or yawning or making some of his "funny" noises which the machine could pick up as HI or AI.