Airsense 11 Baseline Mask Leak Rate

[hobbycamguy]

Does anyone know what the expected baseline mask leakage rate is for the AS11?

I recently switched from an Airtouch F20 mask to a Vitera FF mask to try to reduce the cost of replacing F20 foam cushions.

When using the Vitera, it seemed like a lot of air was being vented out of the group of small holes at the front of the mask. I had never noticed that much air being vented out of the elbow of the F20.

Looking at the specs for the two masks, it turns out that the rated venting flow rates (at a pressure of 10 cmH2O) are almost identical:

F20: 37 L/min  
Vitera: 36 L/min

I was surprised because I didn't notice as much air being vented from the F20.

I'm assuming these mask venting numbers would be the same as the baseline leak rates with a perfect seal to the face (and the mask type set to FF in the AS11 settings). Does that make sense?

Also, does OSCAR subtract a baseline leak rate when graphing leak rate?

Thanks in advance...

[dkemp234]

I had the same experience when I switched from the AirTouch F20 to the Vitera a few months back.  The air is much more noticeable from the front vent holes on the Vitera when compared to the vents on the sides of the elbow connector on the F20.  I was unable to use the Vitera for very long due to excess leakage, and the air blowing out the front, clear across the bed into my wife's face.

The AirSense 11's baseline mask leakage rate should be 37 L/min at 10 cm H20 when the machine is set to full face mask.  This is the spec flow rate for all current Resmed full face masks according to the chart on Resmed's website.

To my knowledge, the algorithm embedded in the machine calculates leakage by deducting the baseline air flow from the total measured air flow.  OSCAR gets the numbers from the machine data and charts them wonderfully but doesn't do the calculations.  I hope this helps.  You will likely get more replies from more experienced people who have more details.

[hobbycamguy]

Thanks dkemp234. That helps validate what I experienced. I did read in another post that Resmed machines subtract the baseline leakage rate internally and only output the excess leakage data whereas Philips machines output both sets of data. I'm sure lots going on "under the hood" which we are not privy to.