I've been meaning to comment on cervical collars... and finally getting to it:
I was put on cpap nearly a year ago. Sleep study showed AHI's in the 40's.
Starting on cpap and with fairly high pressures (started at 14 and was adjusted up to 17 or 18) was putting my AHI's mostly in the teens and I was experiencing a lot of mask leaks. I tried two brands of full face masks and two brands of hybrid masks. I did better with the hybrid (no nose bruising and fewer leaks), but still had AHI's in the teens. While that was a significant improvement to my pre-cpap sleep, it was nowhere near the 5 or fewer benchmark.
I tried a chin strap for one night. Couldn't get it to work well, and more straps over my head meant more discomfort.
I did some reading on this board and one moderator suggested I try a cervical collar. I studied them online and finally ordered a Corflex Ultra on Amazon. I did the measurement from chin to collarbone, wear a size 17 shirt collar, ordered a Medium at 3.5" high.
Wore it the first night. Slept well, AHI less than 1! Since then I use it every night. I average about .7 AHI with that combo. I never realized how much my chin was drooping. The collar helps manage whatever happens in the throat when the chin droops, and it keeps my lower lip inside of the hybrid mask. While I still wish the mask manufacturer made a large mask, not just small and medium, I'm really pleased with the results! I've bought a 2nd collar, this one a large, 3.5" high. Both the medium and large work for me.
I've noticed several people counseling not to wear it too tight. I've found I need it fairly snug, or my chin will slide under it.
My sleep Dr. never suggested the collar, rather just turned up the pressure. With the collar, he's taken the pressure back from 18 to 10 cmH2O. The lower pressure helps minimize mask leaks too.
Thanks to the admins and members of this board for helping me find the real solution to making my therapy work well!