How does S9 record mouth breathing when using nasal mask

-SWS wrote: ...there's a single pneumotach sensor inside the machine used for both pressure and flow calculations. The overall algorithm continuously calculates both.

For the sake of clarity, I should add that these pneumotach flow sensors are comprised of multiple sequential pressure sensors inside a single flow-sensor package. As an example, here is one that Respironics uses:

http://www.sensortechnics.com/download/awm90000-592.pdf
-and-
http://oem.respironics.com/Downloads/Fl ... rement.pdf

So we can see how this type of sensor nicely measures both pressure and flow back at the machine: pressure differential across multiple analogue strain/pressure type sensors are also used to calculate flow. The individual subcomponent sensors are actually pressure sensors; together they comprise a single flow sensor.

robysue wrote:And so in the presence of a leak, the machine is increasing...the flow generator pressure...in order to bring the treatment pressure at the patient interface back to the desired setting

Yes, I think that's worth highlighting so the crucial point doesn't get lost.

Also, here's one more patent link for the technically curious:
Resmed's Determination of Leak and Respiratory Airflow