First night, lots of questions

[rested gal]

Just had my first night (Resmed Autoset Spirit, Activa mask). Things did not go well. I had difficulty falling asleep. After I did, I woke up within an hour with a terribly dry mouth.

I think Knightfall nailed this: "(dry mouth; maybe mouthbreathing?)"

more disconcerting is that my apnea seems not to be treated: AHI was 26.5 according to the data, which is pretty much where it was in my sleep study. Could mouth breathing be the reason here?

That could very well be the reason. Treatment air detouring out through the mouth does not go where it's needed.

Besides setting higher minimum and maximum pressures for the range, as others rightly suggested and you've done now, I think you're going to have to get the probable mouth air leaks and/or mouth breathing under control before you'll see better treatment results.

A full face mask is one solution -- covers nose and mouth, to let you breathe treatment air either way.

Or, look at some of the solutions others have turned to so that they can use whatever mask they like:

Links to: Mouth leaks - Air Leaks - Tape - DIY Guard

[zzzaoem]

Thanks this has all been very helpful. One question: should mouth breathing show up in the leakage data? My leakage seems reasonably small (.1 L/S), (flow is 35 L/m at 11cm). Another issue may be that I just don't sleep long enough for the APAP to get at the right pressure. I have only been able to doze a bit with the mask on (last night was no success either, with an AHI at 36 when I was trying to sleep on my back).