Implications of Expiratory mouth breathing?

[SingleH]

Hi All,

I wanted to ask if there are any issues with expiratory mouth breathing when using a full face mask.

I have noticed that as I increase min EPAP setting, the periods of expiratory mouth breathing frequently get longer and longer. At higher min EPAP's of upto 9, almost 50% of sleep is recorded as expiratory mouth breathing. During these periods I also noticed flow limits go to zero always.

Below is a screenshot at EPAP of 7 and there is a a period of 1.5 hrs of expiratory mouth breathing. Does this impact sleep quality in any way?

       

[PeaceLoveAndPizza]

What are you looking at in OSCAR to determine you are mouth breathing with the full face mask?

[SingleH]

I was looking at the period from 06:00-07:00 and the associated flow rate which looks like the apnea board waveform guide.

Below is the normal wave waveform that occurs for the majority of the night in my original screenshot.

   

And then below is the waveform that appears from before 06:00 to after 07.00 where you see a totally flat line in the original screenshot. The more I raise min EPAP the more time is spent with the waveform looking like this.

   

This wave form likes the the waveform for expiratory mouth breathing.

   

[PeaceLoveAndPizza]

It does not work that way with a full face mask as when you expel air through your mouth it is no different than from through your nose as it all goes back through the same path to the machine. Unless the full face mask has raised above your mouth, of course. Expiratory mouth breathing is specific to using nasal pillows or mask, where air expelled though ones mouth is never seen at the machine.

What I see is flow limited breathing.

[WhyMe]

I also use a ffm, and I was interpreting that flat line as a pause between full exhalation and the beginning of breathing in.

[PeaceLoveAndPizza]

That is correct. The flat line is the pause between expiration and inspiration. If you look very closely, you can see the FOT in the flat line which shows the airway is open.

[SingleH]

Thanks for clarifying, but I dont understand how this can be flow limited breathing when there are no flow limits?

In the original screenshot you will see there are no flow limits during the period when the pressure has flatlined.

In the image below from 3:40 to 4:40 marked in green you have the normal wave form accompanied by flow limits.

From 06:00 to 7:20 you have the flatlined pressure during which there is no flow limits, bar two tiny ones at around 06:45 and 07:05.

   

I can go through dozens of nights on Oscar and see exactly the same thing, 100% flat lined pressure, zero flow limitations compared to normal along with the waveform you describe as flow limited. The higher the EPAP the more of these periods occur and the longer they last. Just to be clear he has flow limits all through the night, the only time he doesnt is when he has this flatlining of pressure and the strange waveform.

I'm confused!!

       

[PeaceLoveAndPizza]

Whatever internal criteria ResMed uses to "count" a flow limitation is not always met by the obstructed airway. You can see the flow limitations in the flow rate waveform with the flattened tops, but it is not sufficient to be counted.

[SingleH]

When you say flattened top in the flow rate waveform are you referring to this:

   

So am I right in saying for whatever reason, during these particular circumstance he has a flow limitation on basically every breath for hours or more, but the machine for whatever reason isnt doing anything about it?

And if so, would could be the cause of it?

[PeaceLoveAndPizza]

Correct. If it does not meet the manufacturers criteria for a FL, it will not raise pressure to compensate. 

What causes flow limitations? Any of a multitude of things from clogged nose/sinus to chin-tucking, and much more. Basically anything that impedes the airflow in the upper airway. How occluded the airway is and the duration shows up in the flow limitation graph.