I have been on CPAP (or Bilevel or AUTO) for 3/1/2 years and have consistently had trouble getting my AHI under 5.  Usually it would be in the teens or 20s.  I had several titrations in the lab and had a lot of hope after the last one that we had found the right pressure- bilevel at 4/8.  When I got home the high AHI continued. I had two overnight pulse ox tests aned never desaturated under 95%.  My sleep specialist is convinced my trouble is due to a long med  list, some of which are sedating and have unknown effects on sleep architecture.  I was pretty stubborn- didn't believe him until recently.  I started making a concerted effort to lower the doses on meds when I could.  When I halved the dose of one med that did the trick.  My AHI is not always under five, but was four last night and is always under ten.  Those of you that know me know how hard this has been.  I am and have been 100% compliant.  After that last titration I started trying to titrate myself.  AUTO was just pushing up my pressures as well as my AHI.  I went back to CPAP at the recommended pressure of 8 and finally settled on 9.4.  I have been taking meds for Excessive Daytime Sleepiness- Nuvigil-and had the doc switch me to a lower dose of Provigil so I can posssibly stop taking it, or at least may need less.

I had a lot of help from RockRPSGT with the titration and read everything I could find about the effects of certain meds on sleep. I learned that doctors seldom have a clue as to what a particular med can do to sleep architecture.  We are just on our own figuring that out sometimes.

I had a lot of support from the forum and I thank everone.