Does sleeping with the upper body at a 45 degree angle affect obstructive sleep apnea?
it usually does - any upright sleeping helps keep the air way open.
I've been sleeping with a triangular support under my pillows for a long time before I got the CPAP, because I had acid reflux. The extra support pillows ended the acid reflux problem, but I still had problems sleeping. Doctor told me that I was a pig and to stop eating so much, stop snacking. (Yes, he really did, I guess for effect.)
After he died I changed medical groups and other doctors diagnosed me with sleep apnea and got me a ResMed machine. The machine works, I don't snore anymore, no acid reflux, and I no longer wake up in the middle of the night. I still sleep with angled support under my pillows, and feel that it helps. Plus I'm working on trying to lose 50 pounds.