So, after about 6 months, I've had a hiccup. Not quite sure what it was that got me, though. I was trying a new pressure (my DME had given me two to try out when I switched to a nasal mask from pillows and I was about 1/2 way through the week trial of the lower of the pressure settings to try), but things were otherwise normal to start. Hadn't had issues in the preceeding days, so wasn't thinking there should be one that night...
Well, a couple hours in, the mask just didn't feel right. I tried re-adjusting but it just didn't want to settle down. Didn't seem to be sitting right at all, including below the nose. Rather than wake up too much, I swapped over to a ffm I have access to. Not my #1 preference, but it got me through the night.
Looking at the numbers in the morning...it was a train wreck. AHI was up almost 10x from my "normal" (still not too bad for therapy, but far from what I had gotten used to) and my respiration rate and tidal volumes were higher too... and centrals...not usually my thing, but I had a swack of them.
So, the next day, I went over things carefully, re-cleaned and assembled the nasal mask, re-trimmed the moustache and went back to the previous week's settings. Basically looking for anything that might have set me off. I don't know what it could have been, but it had to be pretty minor as everything looked pretty normal.
Well, last night, I got ready with a liitle bit of trepidation...would it happen again? Guess what....I slept like a baby. Everything was back to normal...AHI was back down, basically no centrals, no issues with the mask.
Morale of the story: there are a lot of little things in CPAP therapy that can trip you up...not all of them are obvious. Even those who have been on it for a longer time (6 mo, a year, many years) have bad nights. The important thing to remember is that therapy holds a potential for better sleep and better health. Stick with it and use the resources on the forum to help get past the rough patches, especially in the early stages of therapy.