Is leak rate an indicator of mouth breathing?

[EricBoston]

Just finished my first 2 weeks of CPAP. I am not sure if I'm mouth breathing on some nights. I wonder, will the leak rate displayed on my Resmed S8 auto be higher when (and if) I am mouth breathing?

The reason I'm suspicious is that on some nights (but not all) I wake up in the middle of the night with a very dry throat, and my nightly leak rate fluctuates from very low (.06) to around .20 or so. (For my equipment, leak rate is supposed to stay at .40 or below; most people here think it's best to stay welll below that figure).

I didn't mouth breathe on my CPAP titration study, for what it's worth.

Any other clues to mouth breathing I should watch out for?

[TerryB]

A high leak is surely an indicator, but if you are getting dry throat but NOT dry mouth, then you probably just need more humidity. Mouth leaking will really glue your tongue to your mouth.

Try raising the humidifier setting.

TerryB

[Country4ever]

Hi Eric,
I have the same machine as you and use the Swift nasal pillow. When I have taped my mouth firmly shut, sometimes my leak rate is still high, because of leaks around the pillows. I think sometimes when I lay on my side, they get jostled around and air comes out around them.
Also.....if it takes you a little while to go to sleep, your leak rate and AHI can be up, for some strange reason.
But I think, for most of us, if our leak rate is up and we aren't taping or using a chinstrap, you can pretty much count on it being through you mouth.

[Guest]

Thanks for the responses -- they were both helpful.

Country4ever, I've read on other forum posts (here or maybe another site) that the Resmed S8 machines tend to overestimate AHI -- specifically the hypopnea component of the score -- when the leak rate is high and/or when you spend a lot of time fiddling with the mask before getting to bed. I am by no means an expert on this, but if this is true it might explain what you notice. Or not

Eric