fluctuating OAS?

[Tired T]

Can OAS frequency fluctuate on its own?

A sleep study a year ago revealed "mild" OAS, but my sleep doc thought it insignificant. The study also revealed significant PLM, which my doc considered the main problem. After a year of trying various PLM regimens, with no improvement, my doc ordered another sleep study, which revealed OAS in the "upper range of moderate" ('moderate' meaning a middle ground between mild and severe) according to the Nurse Practioner (?) I spoke with the next morning, a level she considered "significant," and the doc ordered a CPAP study. Though glad to have a potential answer to my fatigue problems, I'm puzzled by this variance in results. Some background: I'm 55 and drastically underweight from series of post-viral problems (shingles virus). I'm so thin that at first my doc said it would be a "million to one shot" for me to have OAS. My weight actually went down in the year between sleep studies. I've not had a chance to talk with him directly since the 2nd study, so I haven't gotten an explanation from him. I've been diagnosed with a cross between post-viral syndrome and chronic fatigue syndrome. I've had sleep problems since the initial virus. What role the OAS plays in all this, I'm not sure. (though active when healthy, I was often sleepy, yawning lots during day, before the virus hit; so maybe I've always had some form of OAS?) I don't expect the CPAP to "cure" my CFS; no such cure exists, as I understand it.

Has anyone else experienced such "natural" fluctutations, for lack of a better term? I guess it might not matter; if its bad now, then it can only help to try to fix it. But in my usual skeptical way, I'm wondering if it's even relevant, and to what degree, to my CFS. Sorry for the convoluted questions.

[Julie]

What I saw from what you said is that a year ago you had maybe what was just above borderline OAS, but in the time since, your numbers have risen. That's not fluctuation, it means progression, and I wouldn't wait until you get a 100% definitive answer, but would get set up on Cpap and see if it helps. It's too bad that you've had other problems as well, and they could certainly confuse the issue, but why not be on the safe side instead of hemming and hawing about it. It certainly can't hurt anything. And a lot of us are not overweight, there are anatomic reasons for OSA and weight just seems to be a chicken and egg factor, not necessarily the trigger.

[Tired T]

Thanks, Julie. That's helpful. I considered possibility of a progression, but not knowing much about OAS, I wondered why that would happen now. My obssessive need to know, I guess. I shan't tarry, waiting for things to worsen. I'm scheduled for my CPAP next Monday (and feel much better about doing so now that I've read what so many others have experienced in adjusting). Thanks for taking time to respond. Tom

[split_city]

AHI can be highly variable from night-to-night. It all depends on what posture your in, neck position, how tired you are, sleep stage distribution. There certainly are patients who could be diagnosed as "normal" one night and then diagnosed as having mild/moderate OSA on a follow-up study, even if this study is conducted the following night.

[SleepingUgly]

It could be progression, or it could just be variability, as noted. In addition, if the scoring criteria was different from one sleep study to the next, it can have a significant effect on your overall AHI. There is marked variability in how hypopneas are scored (assuming you had hypopneas), and the different criteria can yield a diagnosis ranging from one end of the continuum to even NO apnea, depending on how they are scored.