I think that you should talk to your sleep doc and present some of this data to him/her as soon as possible. I think that it is ultimately going to require a bilevel machine with a back-up rate to get your CAs down to a good level but that is just my opinion.
Question: Is your Pressure Support currently set at 4?
Good luck with whatever you decide to do.
Question for others: What would cause Sleepyhead to have only one pressure trace for a VPAP? PS set to 0? VPAP in CPAP mode? Anything else?