After being fully compliant with my CPAP for a couple of years I started feeling like it was actually disturbing my sleep.  If I was really tired I wouldn't use the CPAP.  Given that I had lost a good deal of weight (25% of original weight) we decided to do a new sleep study and see what was going on.

I suffer from atrial fibrillation.  My first study showed me to just have mild apnea with an RDI of 13.  Although mild, I went with the CPAP hoping that apnea would not contribute to the atrial fibrillation.  Now, here is the shocker, the second study, when I had lost so much weight had a RDI of 17.6 which is moderate apnea.  My min SaO2 first study was 86% and second 85%. By all scores, even though I am in much better health, my apnea is far worse.  (The one good thing was I was more normal in the stages of the sleep though I note I never went into stage IV at all)

I must say the RDI seems so illogical to me, that I begin to wonder whether sleep studies can really be counted on for a diagnosis and course of action.  Are the variables just so huge in them that one study doesn't mean a thing?  

Any thoughts?

A quick PS, their RDI is the same as AHI, they don't include anything else in it.

Were your apneas obstructive or was a high percentage of them centrals?

But I've known plenty of people of normal weight who have sleep apnea, so while most with the condition are overweight, it's not always the case.  I run a local support group for sleep apnea and I've seen a wide range of folks of different sizes and shapes, not everyone with the condition is overweight.  That tells us that there could be different causes for the apneas even if all are obstructive (the most common form of sleep apnea).  If weight contributes significantly to the obstruction in the throat, then there's a good chance that weight loss can eliminate or lose most of the apneas.  But if the obstruction is due to other causes not related to weight, involving the anatomy of the inside of the throat, then weight loss won't eliminate the apneas.  That's why we tell folks they can be cautiously optimistic about significant weight loss, but there are no guarantees, unfortunately.

The numbers identifying apneas can vary a little in sleep studies due to how they're scored, but that difference isn't significant.  The sleep studies involve pretty detailed polysommography which is reviewed by at least two people, and one has to be someone trained in sleep medicine (medical director of the sleep lab).


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Linda, they did not have any central apneas listed at all.  In fact, I wondered whether they could measure them as it seemed like there should be some.

I agree that not everyone with apnea is overweight -- I like your cautiously optimistic phrase!  Actually I get annoyed with how much people assign to being overweight and not exercising.  I guess if mine had stayed the same I would not feel as if it were all such a waste, but given that I can't tell the difference in how I feel with the CPAP and without it, or if anything I feel worse with the CPAP, and the sleep study results it leaves me wondering what to do and who to trust.  This time the guy even mentioned operations.  An operation when I am not even sure that I believe what is going on?

Only the name of the sleep doctor is listed on the paper, and you never meet him.  It is my pulmonologist who sent me.  He called and told me the results saying that I had gotten better.  I wondered how you could go from milder to milder and still need treatment.  Then I saw the study.  He had bothered to look up the old one -- guess he forgot how mild I was in the first place.  I have written him a letter with a comparison chart.