Nasal mask/Can someone look at my data please

[junior49]

Before I asked whether opening your mouth when using a nasal mask will show up as a leak on resscan. The answer seemed to be yes. As a follow up question, if your mouth is open while using a nasal mask, will the S9 still detect apnea events?

The reason I ask is because several nights ago I used a chinstrap and my AHI was higher, 3.7 after 6 hours; leak numbers were median - 1.2, 95%ile - 8.4 and max - 142.8. Last night I had AHI of 0.0 without using the chinstrap after 5.3 hours. Leak numbers were median - 0.0, 95%ile - 19.2 and max - 160.8.

I'm worried that when I don't use the chinstrap I'm opening my mouth, getting leakage, and no apnea events are showing up. So on the one hand I'm happy to see a 0.0 AHI, but I'm suspicious it doesn't mean anything because I'm opening my mouth. I'd like to not use the chinstrap if possible, but if it means getting better treatment I'll wear it.

[Pugsy]

If your mouth is open enough to be causing a massive leak then the machine loses its ability to sense and detect events and it might simply miss scoring some events giving you a false low AHI.

Need to look at the leak line itself..and evaluate how much time was spent over that 24 L/min line.
If 5 or 10 minutes...probably not the end of the world but if if you spent much time above the 24 L/min mark..then yes..the AHI overall may be falsely low.

95% leak of 19.2 L/min means for 95% of the time the leak was at OR below this number..getting awfully close to 24 L/min but still lower and while pushing things..technically acceptable.
Your maximum...probably high due to repositioning of the mask so I would probably ignore it.
But really, looking at the leak line itself along with the numbers gives you a better indication of just how the leak went throughout the night. You might have had 30 minutes with a really bad leak but the rest of the time..not horrible leak. I have that happen often.. I use nasal pillows and sometimes they just pop out and I don't get them back in right away. While not ideal...it isn't the end of the world to have 30 minutes of perhaps less than perfect pressure over a 7 or 8 hour night.

Note that any leak (small or large) that disrupts sleep is unwanted because we want to limit sleep fragmentation as much as possible.