I was on my second night of nasal APAP with a mouthpiece to assist the seal.  The first night I could not fall asleep, wore it for about 1hr 15 min.  Second night, wore it for about 45 min and took it off again.  (I am confident I will soon tolerate it.)  Right before I took it off, I felt the beginning signs of some sort of headache due to pressure all around my head, even around my face.  Like my head was getting pumped up with air.

Is this normal?  Does this have anything to do with the eustacian tube?  I wonder if it would have gotten worse.... we'll see soon.

I thought I was aware of and had experienced ALL THE MANY problems with CPAP, I guess not!

On second thought, I wonder if it has anything to do with the serious seal that the mouthpiece creates.  It is a Nosebreathe by Dr. Sue in the Bahamas.  Felt like a rock solid seal, pretty intense, even with my low pressures that the APAP chooses (5-10).

With my limited knowledge of biophysics, I know pressure differentials have a weird effect on the body, such as diving and airplanes and stuff. With such a low pressure in my oropharynx, wouldn't that have any effect on the gases in my blood in my head, or at least the tissue in my head?