Nasal Mask / Mouth Leak Queation

[EK3377]

I recently started using a Dreamwear Nasal Mask. Previously I used the ResMed F30 full face mask. I always thought I was a mouth breather while I sleep, so that's why I started with a full face mask. Used it for about a year and a half, and liked it, but had a lot of dry mouth and throat. My doctor recommending trying a nasal mask, that it would help have less irritation in my throat. I started with Dreamwear Nasal Mask with a good Chin strap. I think it's working, but I have noticed in OSCAR data that my needed pressure seems to have reduced. Most mornings I feel like I slept pretty well. My AHI is typically under 1. I am trying to determine whether I have mouth leak. I am not typically waking with obvious symptoms like dry mouth, but I'd like to be sure. I have a Dreamstation. So when I look at the leak data in OSCAR, there are two lines. What am I looking for that would be indicators of mouth leaking? Most nights the lower line is at 0, or very low with a few bumps, but not really spikes. Not sure I am interpreting correctly, but know there are many of you who are experts here. What should I be looking for to indicate mouth leak?

[Pugsy]

You would look for Large Leak flags on the Events graph for one thing. If you had any large leak (no matter the cause) it would be flagged in the LL line on the events graph.

You can also look at the bottom leak line which is real close to excess leak that might come from any mouth breathing.
Normally mouth breathing will show up as a rather large spike on that bottom leak line if it is big enough to be a problem...and also show a gray area for large leak.

If you don't see any gray large leak flagged areas...if you are doing any mouth breathing then it isn't enough to earn a Large Leak flag and I wouldn't worry about it.

[EK3377]

Thanks so much for the guidance, Pugsy. You are always so helpful.

I don't see spikes in the bottom line, just a few bumps and mostly at zero or at a very low level, and don't see events or large leak. Leaks were a lot greater with the full face mask.

Does it seem odd that the pressure needed would be lower when using a nasal mask then a FFM? I went from averaging around 13.5 for 95% to more like 9.5. I also lost some weight, which I know could contribute to needing less pressure, but that was more or less before I made this switch in mask type.

Thanks again for your insight. I greatly appreciate it.

[Pugsy]

Does it seem odd that the pressure needed would be lower when using a nasal mask then a FFM? I went from averaging around 13.5 for 95% to more like 9.5.

Not odd at all. Lots of people have found that they can get by with overall less pressure with a nasal mask than with a full face mask.

I think it has to do with what the full face masks due to the airway and lower jaw with those lower straps. They tend to pull the jaw back a little bit and thus narrowing the airway a bit and makes it a bit harder to keep the airway open optimally so more pressure is needed.
I don't have any proof...but it is logical if you look at your jaw position with the nasal mask and with the full face mask. Most of the time is slightly altered. I know lots of people using 2 to 4 cm (sometimes 5cm) less with a nasal mask.
Another plus to using nasal especially if someone needs pressures in the teens.

[EK3377]

Thanks. Your theory totally makes sense. This is all good news for me. I just wish I'd tried the nasal mask sooner!