For anyone who is thinking of giving up on CPAP because of the nuisance......

[BigWing]

Background: I was diagnosed with sleep apnea just a couple of months ago and I've been on CPAP since then. I was a bit of a scientist in my youth so I have spent some time trying to understand all this apnea and oxygen stuff, and I carefully study the charts in OSCAR and SleepHQ every morning - trying to see how all the parameters interact with each other and relate to the sleep stages measured by my Apple watch.

As we all know, one of the reasons that apneas and hypopneas are bad for us (though there are others, which I will ignore for now) is that they can cause the oxygen level in our blood to fall to unhealthy or even dangerous levels. The CPAP machines typically don't give us any information about oxygen, and even the smart watches that do are apparently not very reliable, so I decided to buy a continuous pulse oximeter (an excellent 'Wellvue SleepU').

I've only had it a couple of days, but the detailed overnight data from it is so far showing that there are no signs of oxygen drop around the (occasional) apnea and hypopnea events recorded on my 'ResMed Airsense 10'. My 'blood-oxygen saturation percentage' is typically 95-98% (which is 'good'), with very occasional brief drops below 95% - the lowest reading being 93% (considered 'low' but not 'dangerous') for just a few seconds.

So that's good - right? Does it mean that I don't really need the CPAP after all, if these events are not affecting my oxygen supply? I thought I would test that theory this morning. For the final 45 minutes of my sleep, I kept wearing the oximeter but disconnected my CPAP gear (i.e. the pillow mask AND chin strap).

During that time, my overall oxygen level was a little lower than it had been but - more worryingly - I had 3 brief drops to 91%, 90% and even 88%! That last one - listed on the charts as 'seek immediate medical attention' - caused my oximeter to vibrate madly to try to wake me, and it did. Coincidentally, my snoring at that same time woke my wife - for the first time in 2 months.

So it seems clear to me that the CPAP machine is doing its job well - it spots apneas and hypopneas in their early stages and quickly increases pressure to curtail them before they can affect my oxygen level. I guess I will learn to live with it!

[Heaviside]

Hi Bigwig,
Thanks for this posting. I had been entertaining the idea of doing a similar study, but you beat me to it!
Good luck with your cpap experience.

[TechieHippie]

I've had similar and even more obvious results too. Keep using the CPAP!  93% and up is excellent.

Just a few notes:
88 for a few seconds is really within the bounds of "normal" - not that normal is healthiest - I think they are saying that if your running 02 is 88 you should get checked medically, but I'm sure you didn't hurt yourself with that experience.  My dad had CHF and COPD and more - they gave him a much lower range of "normal" that went down below 88 (COPD retains CO2 so it's a special case).

I find 87 a better alarm number for my SleepU, because that's the place where personally being woken up is worth it. 

Also, you can look at Average, and time in the various percentage brackets. I feel compromised if I have average <95 or more than a minute or two total under 90%, and really out of it with more. Extreme example for me below, I had 10 minutes under 90% (WITH the CPAP and a collar ) and a low of 77.  Now that probably damaged me some - I've seen worse for myself but not on CPAP. I have a strange thing where exposure to innocuous chemicals really makes my apnea awful at my altitude (goes away at lower altitude but CPAP is cheaper than moving...). AHI was 12.1 here, and I was trying to get back to sleep, super conscious of my body and neck position, but every time I relaxed I had apnea. Ugh.

Have you discovered how Oscar can show you data from both combined?  Here's an example...it's a pain to figure out at first but it's really nice that it combines all the sessions into one night.

[BigWing]

Have you discovered how Oscar can show you data from both combined? 

Yes, and it's very handy!

Thanks for your interesting comments.

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Thanks for this posting. I had been entertaining the idea of doing a similar study, but you beat me to it!

Well, one experiment doesn't really prove much. I would encourage you to do your own also.