SpO2 dip without apnea, breathing pattern question

[rjbutler]

I see this fairly regularly, an extended period, close to an hour here, where my SpO2 levels are low.  During this period my breathing pattern looks a little odd, but I didn't see this pattern on the wiki.  Sometimes there's an OA right before this happens, but last night there wasn't one, not even a short one. 

My typical breathing pattern looks closest to class 6 I think.

Is this cause for concern?  Are there any adjustments I should make?  My AHI is almost always < 1 with the current settings.  Thanks for any advice


I've attached my OSCAR graphs, for the whole night
   
Zoomed during a typical period
   
and zoomed in during the period where my SpO2 dipped into the low 90s/upper 80s.
   

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Oops, I meant to post this in the main forum. I don't see an option to delete or move it though, sorry.

[OpalRose]

rjbutler,
I moved this thread from the Software Support Forum here to the Main Forum.

[Apnea23]

Typical Resmed algorithm; ignoring the obvious inspiratory flow issues leading to extended periods of hypopneas/waxing/waning/fluctuating o2 levels.

I would either keep your APAP range the same with EPR off, or fix pressure at 8cm and EPR off, then repost results.

[rjbutler]

   
Thanks @Apnea23, I tried with EPR off last night and had a lot of mouth leakage and mask leakage.  I'll try mouth tape and tightening the headstrap a bit tonight.  The O2 levels looked slightly better overall I think, but there was still an extended dip around 94-95 and one big dip after a hypopnea/apnea event.

I zoomed in on the period just before the drop below 95.  Let me know if there's anything else that would be informative.

Thanks for the help

[Apnea23]

Full face mask? If so I wouldn't tape.

I personally would use fixed pressure at 9cm (not an APAP range) or try fixed pressure 11cm with 2 EPR and see what happens. I only say the latter because I think that flow rate needs some assistance in rounding.

I'm not an expert but I think your pressure has been far too low, and the EPR just nosedived it on exhale even more so, contributing to or making it even harder to overcome any obstructions on inspiration.

[rjbutler]

No, nasal pillows. I woke up a few times leaking from my mouth and a few times with air leaking from the pillows. I had it fairly loose with EPR on and it was fine, but I think the extra pressure on exhale means I need to tighten it a bit.

[gainerfull]

With your huge sp02 dip it looks like it's happening while your mouth is open / or you're experiencing mouth drop based upon the leak data. It also looks like you had an arousal based upon the breathing pattern. Once you get your leaks sorted it will be interesting to see if your sleep quality improves.

[rjbutler]

I didn't have a problem with leaks before turning off EPR, so I assume it's the added pressure on expiration that's forcing my mouth open. I've tried taping in the past and ended up taking it off during the night, but I'll try again. Or maybe I should try gradually reducing the EPR to zero rather than all at once to see if I can get used to it. I'll try the tape first though.