Mouth Leak vs mask leak

[Mjmcd]

Hi All

Just looking for specific guidance on what to look for within Oscar to identify if the large leaks are mouth or the mask.   I just got a P30I Mask so want to rule this out ....I suspect its mouth popping open but just want to ensure by checking the charts ?

Appreciated the assistance.

[staceyburke]

If you look at the leak rate chart - a fairly long (1 to ? Minutes) with a FLAT top shows a mouth leak, spike type is a mask leak. Also if you zoom into your breath chart you can see flat top on each breath instead of a round top shows mouth leak.

[Mjmcd]

Awesome thank you

[multicast]

You might take a look at the flow rate. Watch the zero line.  A flat passing through the zero line might indicate a mouth leak:

   

A steaper passing through the zero line is an indication of a mask leak:

   

But remember, we're all looking in the crystal ball ...

Mike

[sheepless]

interesting, multicast. I haven't seen this interpretation before. assuming I'm reading your graphs correctly, it looks like they might be switched? the first one looks steeper while the second looks flatter.

I frequently see the suggestion that mask leaks show as spikes in the leak rate while mouth leaks show as longer. I wish I understood this topic better. I just don't buy that duration is such a clear demarcation between mask and mouth leaks. it's an indicator, to be sure, but I don't understand why mask leaks can't last as long as mouth leaks.

also, I'm thinking that leak indicators may be different for different mask types, i.e., full face vs nasal/nasal pillows. in addition, there's mouth breathing (inhale and exhale) and there's mouth leaking (exhale, at least in my experience). I think these can be differentiated (for nasal pillow masks at least) in the flow rate by comparing above- and below- zero volumes. but again, I can't say I really understand all this.

[staceyburke]

This is what I am talking about - almost all are mouth leaks until the 6:00 time then this is a mask leak.

[multicast]

No, they aren't switched.  Look at 1:42:50 in the first shot: a very flat passing through the zero line.  Here are two more pics, first a mask leak, second one a mouth leak -- all seen through the crystal ball, of course:

   

   

And here's another (massive) mask leak:

   

The topic ist delicate.  Remember that the (ResMed-) machine only have two sensors to measure the pressure: Air from outside -> flow sensor -> ventilator -> pressure sensor -> tube.   (The flow sensor is also used to determine the kind of hypopnea via FOT.)  See here https://forum-schlafapnoe.de/viewtopic.p...09#p113857 for a tear down of an AirSense.

As far as I know they're actually measuring the volume of the air from which pressures can can be calculated.  Remember also that there always is an intended leak which somehow must be taken into account ...  

Here's what I presume, very much oversimplified.  Remember also that OSCAR doesn't make any calculations on the flow rate regarding machines by ResMed, these are data provided already calculated by the machine.  (Hence, e.g., the zero line is always only *estimated*.) Now the flow rate is the the actual speed of the air stream which is zero at the beginning and the end of one breath.  When you wear a nasal mask and you breathe out by the mouth *no change of the flow rate can be detected by the machine* as there is no way to detect a change in pressure (despite actually there is one) hence the horizontal passing through the zero line.  

In the end, these insights are all crystal-ballistic.  

Mike

[multicast]

FWIW, here's a pic of extreme breathing.  Up to 19:11:45 I was solely breathing through my mouth. From then on inspiration through the nose, expiration through the mouth.

   

(You may also notice FOT starting around 19:10:45.)

[sheepless]

interesting! I learn something with every visit. thanks for elaborating multicast. and you're right, of course - despite thinking I'd double checked, I must have mixed up the graph sequence I questioned.

[OpalRose]

Moving this thread to the Main Forum.