If you look at the sinus picture above, you can understand that if you pressurize your nose that your sinuses also get pressurized. Before you were on CPAP what did sinus pressure mean to you: cold, congestion, plugged nose. If when you feel congested, you take the mask off and are magically no longer congested-it was the pressure.
There are several things with CPAP that can make you feel like you can't breathe: too high or low humidity, too low a pressure, using ramp with too low a starting pressure, EPR or in your case flex setting-exhaling into pressure, just not used to the alien sitting on you face blowing air up your nose, using too small of a mask-exhaling into pressure.
If you feel this way when awake with the CPAP on, make some small changes and see what makes it better
When I put my mask on and I sleep face up I can breathe very slowly, then I get on a side when im falling to sleep like a rock and one of my nostrils feels like it collapses and closes, the other one is a matter of minutes before it closes up on me, there is no mucous just like if I had a plug inside the nose and no air at all goes in even if i breathe in hard. At that point I wake up gasping for air since my mouth is acting up when I open it due to the pressure, I was ready to go buy the mouth + nose mask, should I hold off then? and mess with the settings?
If i take the mask off it takes quite a few minutes , maybe an hour or two for everything to open up and allow me to start breathing trough my nose. right now I still feel a little congested (about 40%) and is 12:00 pm at work.
I tried the same mask in my sleep study and my nose just wont open up for it.
The nose and mouth may solve everything, it does not matter how the pressure gets there, just that it is there, and then again it may introduce other things like dry mouth and leaks (my FFM works just fine for me).
With me it was like my nose would swell shut, like self inflicted congestion. I could get this happen even before I got to the bed room, just thinking about CPAP. The right settings and getting used to it stopped this. I remember telling myself to "just stop it, you are NOT congested" after a while I believed it.
GUYS !! IM SO HAPPY!! I SLEPT GOOD FOR 2.5 HOURS IN A NAP!!
I finally got a hold of the kaiser sleep clinic, They recommended i increase the humidifier setting from the original factory default.
I learned about preheating so i did and cranked it up to 5
My nose was clear the whole time and my AHI dropped from 12.50 to 1.78