A setting of 4 on a ResMed machine really isn't all that high of a setting and if one lives in a relatively humid area that setting probably doesn't really add much (if any) moisture to the cpap provided air.
Here's how it works...the setting (whatever it is) for humidity is what the machine is supposed to ultimately deliver...not added on top of what the incoming humidity might be.
A setting of 4 is sort of the middle of the road and I forget exactly what it translates to but probably something around 80%...so lets say that is the target.
If the incoming air is say 65% humidity then the machine only needs to add 15% more moisture and then it stops once the air contains 80% moisture. If the incoming air is 75% humidity then the machine only adds 5 % more...
If the incoming air is 90%...like it is raining outside and the windows are open...the machine won't add any extra moisture and won't use much, if any, water.
Don't assume that one's ambient humidity in the house is the same as what it is outside.....when we heat (or cool) our homes the ambient humidity inside will change. Example...suppose we lived in a high humidity locale...say the middle of the rain forest but we used air conditioning all the time because it was always really hot in that rain forest....using A/C dries out the air inside the home so the humidity inside the house is going to be a lot lower than outside the house.
Or another example....suppose we lived in the state of Washington in the US...don't assume it is high humidity for everyone...those mountains in Washington cause for a marked difference in ambient humidity. People on the west side of the mountains will have high humidity but the people on the east side of the mountains actually have a very arid/dry ambient humidity. This is what they start with but add in heat during the winter they both will have even drier air to start with even before getting to the cpap machine for the machine to do whatever it is going to do.
Nasal mucosa are funny little guys and very easily upset when something changes the least little bit.
Yes...we breathe the ambient humidity where we live all day long so our mucosa is adjusted to their "normal" but adding cpap flow rate per the pressures can upset the balance. It can simply dry the mucosa out a bit and when the mucosa experiences anything different from their "normal" it can respond with histamine production and we get those typical allergy like symptoms that we don't like....congestion, drainage, stuffiness, pressure, itching, swelling, etc.
This can happen with any change...be it too much moisture or too little moisture. The nasal mucosa are simply unhappy from the change no matter what the change might be.
Conor2612 wrote: ↑Fri Nov 26, 2021 9:35 am
I live in London, the air is generally neutral/to humid cos of the rain. I truly think this is a sinuses getting used to breathing on 10cm of air pressure thing. Especially if they were completely fine on 7-8cm of air pressure.
I just want to know if anyone has experienced this and it's just my sinuses adjusting?
The flow of air from the change in pressure from 7 or 8 to 10 cm is actually relatively small but it is enough to potentially dry the mucosa out a bit quicker. In the end though it does fall back on the mucosa and whether or not the change makes them happy or unhappy.
So we have to back up and factor in the ambient humidity in the bedroom (not necessarily outside the house because remember we have to factor in heating or cooling) and what the machine is doing or not doing at that setting of 4. It's going to try to maintain that 80% (assuming that the setting of 4 is what gets delivered) but with that little bit of increased air flow from the higher pressures that 80% might not be enough to keep the nasal mucosa happy.
So while you want to blame the pressure change...it might be the moisture itself still being the underlying real cause brought on by the slight change in pressure.
Since the machine will only deliver the humidity it is set to and not more....the chances of your getting too much humidity is slim to none but the chance of your not getting enough moisture to keep your nasal mucosa happy have increased a bit with the slightly higher pressures and the no change in delivered humidity.
If it were me...I would slightly increase the humidity setting and see if that helps with the congestion or not.
Nasal mucosa are funny little guys and sometimes the least little change will set them off into a really unhappy mood.
When they are unhappy....they make us pay with some really nasty allergy like symptoms.
If a hot steamy shower seems to help relieve nasal congestion...you have your answer right there.