I am suffering from similar issues. The one thing consistent about central apnea is that it is inconsistent. My last few nights have been very poor with AHI in the 7.x range. At times I am convinced that the weather and specifically the atmospheric pressure influences the rate of central apnea. I'm quite sure higher elevations makes it worse, which is kind of the same thing, a change in atmospheric pressure.
Overall your readings still look pretty good for someone that is experiencing central apnea. I would not get real concerned until you start to average over 5 for AHI, and then it is worth a doctor visit.
I can't remember, are you using SleepyHead? If you are I would look at when the centrals are occurring and at what pressure. There may be an opportunity to reduce the maximum pressure, or even go to a single fixed pressure (CPAP mode). If you post a daily report from SleepyHead I could give you my thoughts as to the potential for a pressure change improving things. I just went through a two week trial using a lower pressure and it was not successful. Trying it, is about the only way to know for sure if it works.
Yes I use Sleepyhead. What I have seen there as well as when roughly correlating sleep data from my Fitbit is that, as I may have noted as part of another earlier post, the CAs seem to arise, sometimes in clusters, at sleep transition points. This is especially true at the very front end and final back end of a nights sleep and also especially if I get up to use the bathroom during the night. There seems to be a stuttering handoff between waking breathing control and the neuro-chemical side of sleeping control. Does that make any sense and/or have you seen this?
I have observed that the better the sleep I get the fewer CA events I get. If the room is too hot or other things disturb my sleep my score gets worse. When you are semi awake I think one is more likely to get flagged for CA events. Some call it Sleep Wake Junk, and kind of dismiss it. There is probably some logic in that, but an interruption is breathing is still an interruption.
I plot Minute Ventilation as well as my other variables and I usually can see a cycle in MV that leads up to the CA events. It is an indication of the unstable breathing control that is a contributor to central apnea.
The big concern about CA is whether or not it is an indication of heart issues. If it becomes a problem (consistently >5 AHI) it is worth a visit to a GP or cardiologist to make sure there is not an underlying problem.
Francesco: With the small amount of CAs you are having I wouldn't worry much about it. Getting the lowest numbers is not always the best for yourself. It is how you feel, there is no point in getting a low AHI if you feel worse, sometimes getting a low number affect your sleep quality. If it is quite low, you feel good, do not fret about getting it lower. Sometimes getting it very low results in CAs increasing, it is a catch 22. If your AHI is below 5 and you feel good and not sleepy during the day, accept you feel fine and stop worrying.