APAP vs CPAP question

I have been using my ResMed Autoset 11 in Cpap mode for quite a while now and have lowered my pressure from the titrated pressure of 12 to 10.2 to try and avoid the horrible aerophagia I have experienced at high pressures. Lately, I have still been having some bloating even at the 10.2 pressure and wondered how I would do back on the APAP. I haven't used the APAP much because in the past it usually left me feeling more tired and generally less alert.
I put my APAP on a setting of 9.4-13.0 for a week or 10 days and as always my stats were very good with a 90% pressure of generally around 9.8 and a very low leak rate and low AI and HI( usually a little higher HI than on CPAP but nothing significant). I had the same reaction as always of feeling less rested and foggy and sleepy during the day. But I did notice that my morning stats are lower with the APAP set at the 9.4-13.0 range than with the CPAP. However with the CPAP I don't feel quite as tired even though my overnight stats are higher( higher AI, HI, leak rates about the same as on APAP).
Why would my overnight stats be higher with the CPAP at the higher pressure than with the APAP set at the lower pressure? I thought that the AI, HI would be lower at the straight CPAP higher pressure than with the APAP? I don't want to lower my CPAP pressure much lower because when I have done that in the past I feel very tired-even when set at a straight 10.0.
I don't expect any of you to have a real solution for this since I suspect it is just an individual kind of thing but I was just curious if anyone had any theories about why this happens. Thanks- Grumpygirl

What's the maximum pressure the machine really reacheswhen it you run it in auto mode?

O.

The highest pressure I have seen lately in auto mode is 10.0 and that was only once. It usually reads 9.8 or 9.6.

I believe ozij's question may be the key:

ozij wrote:What's the maximum pressure the machine really reacheswhen it you run it in auto mode?

My two cents is that it can take a while to get used to a machine in auto mode. It may cause brain arousals until you get used to it, which can make you tired the next day for a few weeks. It may be that some never get used to the changes in pressure occurring, but I believe many do get used to it if they invest the time into acclimating to it, similar to the time we invest into getting used to PAP therapy itself. That is one area in which, as you said, everyone is different.

As I understand it, though, the idea with autos is that they stay at a lower pressure much of the night then raise pressure, if needed, to prevent events that would otherwise occur in a particular position or when you are in a particular sleep stage, for example. Then the pressure goes back down. So if you spend less time at a high pressure, that should decrease the aerophagia trouble, theoretically. But that won't make you feel more rested until you get used to the changes in pressure that occur with an auto. Hopefully you will, if you decide to pursue that option. That may be at least part of what you are observing with your experience, if I understand your question correctly.

That is only my take. The key to a more scientific explanation would be more a matter of the answer to ozij's question, I'm sure. If you have software, it will show how high your pressure goes when in auto mode. All the screen gives you is the 90th centile figure you got, around 9.8, as you said.