I suggest see your sleep doc. CPAP doesn't treat CA
Were there any CA in your sleep study
It looks like something real to me.
Zoom in and look at the airflow waveforms of some of the apneas you're having. Are they long, close together, full or partial airflow restrictions, etc.?
Is there any chance you're awake during the bad period?
By the way, everywhere but SleepyHead, "AHI" means average apneas for a whole night's sleep, not just over a one hour period.
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If it's midnight and a DME tells you it's dark outside, go and check it yourself.
quozl, my reading of your data agrees with what you see there. It does not appear that your AHI numbers are being compromised by a too high leak rate. However, like Zonk and archangle indicated, that CA seems to be calling for attention. It's just as high as the AHI number in the data you attached. Even if it's more like a 3 most nights, that still appears to be large enough to warrant some attention when you next see the doc. One other thought to share. If your AHI averages around 8 over time, it's possible that you're getting the best therapy you can. I offer that in light of my sleep doc telling me early on that although <5 AHI is the goal, I may not be able to reach that. He told me this along with the report that my apnea has proven challenging to control. It's possible that your apnea may also be difficult to get under that "magic" number of 5.
I have noticed with my Resmed s9 Autoset that the CA's are generally me opening my mouth during my sleep. I had no central apneas in my sleeps study and now my autoset tells me it is between 0.1 and 1.2 a night. Hope this information is of some help.
Check to see when those CA's are occurring. I would bet they are occurring during wakefulness, and they probably aren't of any significance. That can be proven by measuring your O2 saturation simultaneously. You probably won't see any signficant desaturation during these "centrals".
Here's my take on these so called central events. I had them, too, when I attempted to up my starting lower pressure limit. When awake and tryhing to fall asleep, we are initially uncomfortable breathing out against this too high initial pressure. We just aren't used to it. We begin to hyperventillate to overcome the pressure, and then try taking "breathing breaks" where we don't breath for several seconds, which becomes easy to do after hyperventillating. The machine records a central, though there probably isn't any desaturation. Though it doesn't need fixing since it isn't hurting you (it is only hurting your AHI), you can get rid of these "centrals" by lowering the starting pressure, or by ramping up the starting pressure from a lower pressure.
Longer periods of before falling asleep are seen with new cpap users getting used to higher starting pressures, or new masks, or both. You can also see these "centrals" when you awaken and are just laying there in bed thinking about your breathing. We tend to hyperventillate and then take "breathing breaks", since it is much easier to breath out with a deeper exhalation and then inspiration, or just not breath at all.
Is it possible that the period of time your AHI shoots up is when you are in REM sleep? Maybe you need a higher pressure for a portion of the night?