determination of pressure at mask

[rdlyons]

How does ResMed Airsense 10 Autoset determine the pressure at the mask? The mask is at the end of a long tube as well as a frame that can be made by a different manufacturer.

Related questions: How does the machine affect this pressure for detecting whether the airway is clear, and why does the graph of "pressure" stay essentially constant during these times? This cannot be due solely to the fact that the latter is measured once per second while the former is measured 25 times per sec.

[mlmollenkamp]

In engineering terms ResMed builds a mathematical model of the mask and tube.  There is a setting in the machine for pillows, nasal or full face masks.  The main difference is the volume of air inside the mask. I'm pretty sure the machine determines the specifics during operation. If you dig enough its covered in some of their patents, use Google patent search for patents assigned to ResMed.  There is a lot going on in these machines, fixed pressure machines without reporting can be very simple.  Reporting and operation go hand in hand, the machine has to determine if you are having an event to know what to do next, I believe ResMed actually predicts events in advance based on the pressure waveform.  Its all pretty amazing to me.