Do "centrals" always increase with increased pressure?

I reduced my pressure by 0.5 cm last year, and because I saw an increase in AHI, I switched back. My AHI has been at an average of 1.60 since then. Then out of curiosity I took a look at the 4 nights where I had the lower pressure: the frequency of CAs was actually HIGHER than previously, or since. So, my question is that since there was an increase in CAs with a 0.5 reduction in pressure, what is the likely effect of a 0.5 cm increase in pressure? My sleep study, almost 2.5 years ago, showed my optimal pressure was 8, but I was snoring at that ... my sleep doc raised the pressure to 10. Without having another sleep study, is it possible to know whether an increase would work, or whether I need a more advanced machine to adjust to different pressure needs throughout the night.

I believe that 4 nights might not be a representative sample.
Of course, our titration--typically one night--is considered cast in concrete.
Those of us with data know this to be an illusion of convenience--(theirs, not ours).
If those four nights were consecutive, there could be other factors causing the 'centrals'.
I would allow each setting at least a week to settle in,
and read the detailed data to eliminate false readings due to semi-asleep events.

Edit: When I changed to my Autoset from my Elite, my pressure dropped from 14 to around 11 cm.
At this time, my average AHI dropped as well--a point or two
Since I did not record CI with the Elite,(I wish I had) I can assume a fair portion of my previous AHI was centrals
--perhaps even a higher percentage than they are now.

So, yes, if you get an APAP, it can be different--and if not, you can switch back to CPAP mode.

Thanks, ChunkyFrog. That has given me things to consider - maybe a week of the lower pressure ... During those 4 days, I do see some variation. Not sure how to eliminate those "semi-awake" events, though. Can you provide a little more explanation on how I might do that with SleepyHead? What I do see is that the CAs seem to be associated with slight reductions in respiration rate - but which is responsible for which, I don't know. Also, it makes sense that if you forget to breathe the respiration rate would drop... On the other hand, the rate doesn't seem to rebound all that quickly, although further centrals are not recorded for quite some time (30 minutes or more).

Sorry, not into Sleepyhead yet--still working full time--gotta pick and choose.
My therapy is satisfactory, and I try not to let the numbers rattle me.

One thing you learn about sleep apnea and therapy is that it is very individual. Nothing results in the same results all the time for every person, or even the same person. That is why we look at trends. I prefer a 7-10 day range of data before making any inferences or changes. It's good to be paying attention though. I check my LED screen every morning, but have an S8 which doesn't report centrals as clear airway events, but I assume as apneas or hypopneas.

Reducing pressure should decrease "centrals" and increase obstructive apneas. But as has already been stated, everyone's response is different, however the general trend is for snoring and obstructive apneas to predominate when below optimum pressure, and central or non-obstructive apneas to predominate when too much pressure is applied. Somewhere in between the extremes is where you want to be.

The Hering-Breuer reflex will become apparent when too much pressure is applied. It's function is to keep the lungs from over-inflating during inspiration. So if you have too much pressure, stretch receptors in the lungs stop the intake of air and you stop breathing until CO2 levels rise in your blood and you resume breathing. Your machine will call that a central or non-obstructive apnea, even though it is the CPAP pressure that is causing it.

My pulmonologist explained to me that you can anesthetize a rabbit, intubate its lungs with an air supply and the rabbit will stop breathing on its own. Stop supplying air and it resumes breathing. It's important to be aware of the difference between a true central apnea and one caused by the Hering-Breuer reflex. Some people freak out when they start seeing lots of "centrals" being recorded, when it's usually just an artifact of CPAP therapy. That said, your doc should hear about it and be the one to tell you what to do.