2 peeps with OSA -- why R symptoms SO different?

Bear with me here.

My MIL was recently diagnosed with OSA. After I got my diagnosis in January 2009, my hub and I talked to her about participating in a sleep study. I had been vaguely aware of the symptoms of OSA, and, post-diagnosis, felt strongly that she might have it.

Why? Loud, continuous snoring, such that her husband slept apart from her for most of their marriage; she is quite obese; and she falls asleep at the drop of a hat - multiple naps during the day, plus lots of discussion of "being tired." She falls asleep just sitting still on the couch, and she voluntarily stopped driving several years ago out of a fear that she would fall asleep driving.

She went for a sleep study and was told her untreated AHI is 19.

I'm really surprised by that. Should I be? My untreated AHI is 91, and I would have passed the Epworth Sleepiness Test in a snap. I only started to fail some of the EST questions when I encountered the health crisis that lead to my sleep study and diagnosis (the crisis was that I could not maintain 02 sats above 90%. My docs thought I had some kind of heart failure).

So here's my question: why is my OSA so much more severe (as measured by AHI), but my symptoms so different (I am not going to say "milder")? Why are her symptoms seemingly so much more "severe" (or so much more typical?), but her AHI is so much lower than mine?

Is this a function of age, or our relative physical fitness, or is it psychological, or do symptoms *really* just vary that much by person -- i.e., a relatively "mild" AHI will cause significant symptoms in one person while very severe AHI will lead to few symptoms in another?

Any input, thoughts, advice welcome. (BTW she got fitted for a CPAP but has been unhappy with her masks. She's going to try a new DME. I don't think she's experienced a 'good' night on CPAP yet, so I don't have any sense of whether CPAP is making any difference for her yet.)

"AHI" is not everything there is to do with getting restful sleep.

A person could have a very low AHI; indeed, even an AHI that was so low they didn't even qualify for having "Obstructive Sleep Apnea", yet have such disrupted sleep for other reasons that they were as sleepy and tired all the time as your mother-in-law is.

Without seeing her entire sleep study report (not that I would understand it!) you can't know if other sleep problems come into play. Perhaps she has tons of arousals all night long from meds, pain, UARS in addition to outright OSA, and who-knows-what-else. Could be hormone issues, low thyroid, lack of proper vitamins/minerals, list could go on and on.

MoneyGal wrote:Is this a function of age, or our relative physical fitness, or is it psychological, or do symptoms *really* just vary that much by person -- i.e., a relatively "mild" AHI will cause significant symptoms in one person while very severe AHI will lead to few symptoms in another?

Could be the relative physical fitness plus other health issues, med side effects, sleep hygiene, any number of things.

"do symptoms *really* just vary that much by person -- i.e., a relatively "mild" AHI will cause significant symptoms in one person while very severe AHI will lead to few symptoms in another?"
Yes. That certainly can be.

Yep, simple AHI comparison doesn't tell the full story.

Here is my example. During initial sleep study it was determined that during non REM sleep my AHI was only 11. Hmmmm not bad at all. I didn't start rocking and rolling till I hit REM sleep (235 minutes to get to REM) when I hit 53 per hour
BUT.... during the non REM sleep with the events I had some pretty long events (40 second apneas) and desats to 73%.

Add in whatever else can affect our overall well being and you have so many variables that I suppose no one is truly "typical".

Thanks for your reply!

What you've said makes sense. But now a new question from me: if her OSA is relatively mild (please not I am using that term "relatively" advisedly -- I mean relative to mine, and relative to her reported symptoms - which suggest, to me anyways, a much more severe problem) -- then how much will CPAP help her?

Put another way, if someone has a lot of sleep issues, with OSA only one part of the picture, then perhaps they don't experience relief from "poor sleep" not because their CPAP therapy is not working well...but because they have other sleep issues which CPAP won't treat...right?

Oy. I can really see the importance of informed doctors and unstoppable patients!

x-posted with you, Pugsy. Thanks for that reply, as well...what you've written also makes a lot of sense to me.

MoneyGal wrote:now a new question from me: if her OSA is relatively mild (please not I am using that term "relatively" advisedly -- I mean relative to mine, and relative to her reported symptoms - which suggest, to me anyways, a much more severe problem) -- then how much will CPAP help her?

There's no way to know until she tries it. And even then, she's probably going to experience sleep disruptions from the equipment itself (mask, machine) for awhile. Those disruptions may make her feel even worse than before, until she gets all the comfort issues about "cpap treatment" taken care of and has gotten used to the therapy.

MoneyGal wrote:Put another way, if someone has a lot of sleep issues, with OSA only one part of the picture, then perhaps they don't experience relief from "poor sleep" not because their CPAP therapy is not working well...but because they have other sleep issues which CPAP won't treat...right?

Right. CPAP therapy can be doing its part of the job perfectly, yet a person can still feel sleepy, tired, exhausted, fatigued, worn out, awful... from other issues. Can even be from other sleep disorders like PLMD (Periodic Limb Movement Disorder.) That would show up on her sleep study.

I guess there are so many different reasons why one person could have a high AHI and someone else a lower AHI, yet they both have OSA. I'm not sure if my story will help, but I thought it might be related:

I am about to have a sleep study this Friday night. What I am expecting is a relatively low AHI, even though my drowsiness level is really awful. The reason I think my AHI is relatively low is because my OSA has made me a very light sleeper. I think my body's way of compensating for the OSA is to basically stay "partly awake." I think my doctor told me from my last study that I did not spend a whole lot of time in Stage 3 & 4 sleep, or at least relative to the amount of time I should be spending. So while I don't have a whole lot of obstructive events compared to some people, I don't fall into the deeper more restorative phases of sleep as much as I should, which means I don't get the refreshing type of sleep I need, hence my daytime drowsiness is really very bad. Yet, you would never guess this if you only looked at my AHI.

It took me several years to figure out the above...

Count alone can be so deceptive. One person could have 60 events per hour that last only 20 seconds each, oxygen never drops below 90%, and most never cause arousals or disruption in sleep stages. The next person could have 20 events per hour that last at least 45 seconds each, oxygen drops with most to about 73%, and almost all cause arousals. I'd venture to say the first person fares better than the second one, in spite of their counts.