Does mask SIZE make a difference (regarding pressure)?

[Broomstick]

For example, would switching to a larger mask mean that the air gets less concentrated and therefore the pressure should be increased to accommodate? 

Y or N

[Fats Drywaller]

N. All you need to do is to make sure that you've set the mask type correctly in the machine's settings: full-face, nasal, or nasal pillows/cushion. That's Resmed. On the Philips machines, it's done with the "resistance" settings, X1 through X5 or off (X0).

[SarcasticDave94]

Agreed with FD on this. The CPAP (mainstream branded items) has that compensation calculated via that mask setting. And if you mean changing cushion sizes, IMO there isn't enough volume change to be concerned about.

[Walla Walla]

I've found even when setting the correct type of mask on the machine, that a increase in pressure of 1cm or so is required when going from a pillow mask to a full face mask.

[SarcasticDave94]

Safe to say then "It depends on the user" is an answer to consider?

[DeepBreathing]

My experience going from Resmed F10 to F&P Simplus (both full face) is that the Simplus required on average 1.5cm higher pressures to get the same consistent results. The Simplus has a substantially bigger volume.

[Fats Drywaller]

??? Your lung volume doesn't change when you use a different mask.

[Broomstick]

???  Your lung volume doesn't change when you use a different mask.

Yeah, but the air has to fill both your lungs and the volume of the mask. A larger mask should, in theory, give the air more room to spread out, thus diluting it's concentrated power. 

On the other hand, the machine is supposed to be able to compensate for leaks, with reason,  (I think) and perhaps understands how to keep the pressure consistent based on the pressure it senses pushing back. 

All I know is that I seem to be having better numbers with the medium, but it's too early to tell. Leak rate was the same with both masks.

[Gideon]

Leak rate was the same with both masks.

Are you sure?  Keep in mind that larger masks would need a larger "Intended" leak to purge the exhaled Oxygen Carbon Dioxide (CO2).

to the OP, it is not at all uncommon to need to tweak settings when changing the delivery system, not always, but not uncommon.  I believe that a change in the volume of the system is the largest factor.

Fred

[Broomstick]

My experience going from Resmed F10 to F&P Simplus (both full face) is that the Simplus required on average 1.5cm higher pressures to get the same consistent results. The Simplus has a substantially bigger volume.

This is what I'm thinking. I just had a much higher AHI than average today and the only variable is this larger mask. It's too early to tell, but this is something I've been thinking about for a while. I will report back on my experiment after a few days.