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I would in no way conclude from that study that AHI would be higher in a CPAP user using CPAP when mouthbreathing as compared to nasal breathing. I would also not conclude that higher pressure would be required.

To test this hypothesis, the authors compared upper airway resistance during nasal breathing and during oral breathing in healthy sleeping subjects with normal nasal resistance.

Normal subjects were used for the study and GOOD GRIEF, look and read about how they were rigged for the study:



How could anyone sleep or breathe in a way that approximates "real life" while rigged like that.

Nothing that I would trust could come out of that study.

Chad, You need to be looking less at the AHI and more at the detail time line of events to figure out what is happening. You probably don't have a large enough sample of nights with tape and nights without to make a conclusion.

Dori may have addressed the crux of your problem - your minimum pressure is set too low. I would bump it to 10 and if you are not satisfied then take it to 11 and eventually 12 if needed.

If you find a higher pressure that gives you the therapy you want and things are stabilized, then you can start dropping it 0.5 cm per night to see if a lower pressure will work as well.

This study had nothing to do with sleep. It showed nasal resistance rose when normal subject opened their mouth.
That's all, and it may explain what AHI rises when the OP lets his mouth drop open.

ozij wrote:This study had nothing to do with sleep.

Are we reading the same study?

However, during sleep (supine, stage two) upper airway resistance was much higher while breathing orally (median 12.4 cmH2O·L−1·s−1, range 4.5–40.2) than nasally (5.2 cmH2O·L−1·s−1, 1.7–10.. In addition, obstructive (but not central) apnoeas and hypopnoeas were profoundly more frequent when breathing orally (apnoea-hypopnoea index 43±6) than nasally (1.5±0.5).

roster wrote:Chad, You need to be looking less at the AHI and more at the detail time line of events to figure out what is happening. You probably don't have a large enough sample of nights with tape and nights without to make a conclusion.

Dori may have addressed the crux of your problem - your minimum pressure is set too low. I would bump it to 10 and if you are not satisfied then take it to 11 and eventually 12 if needed.

If you find a higher pressure that gives you the therapy you want and things are stabilized, then you can start dropping it 0.5 cm per night to see if a lower pressure will work as well.

The fact remains that for some people, there are fewer events when using the same pressure of CPAP while breathing through the nose than through the mouth. It just happens to be the case for some of us. I have several months of data both ways with a huge difference (AHI of 5 vs 2). Now it could be that Chad could get away with mouth breathing provided he raised his pressure. But he may also prefer to leave the pressure lower and mouth tape. And end up with the very same results.

bb27:
> I was wondering why my AHI would be overall better when I tape my mouth closed
> when using my resmed mirage liberty full face mask

I thought FF masks were prescribed for those of us who can't breathe through our noses. (True for me.)

If I taped my mouth I wouldn't be able to breathe at all.

xyz wrote:
I thought FF masks were prescribed for those of us who can't breathe through our noses. (True for me.)

If I taped my mouth I wouldn't be able to breathe at all.

Might be a good idea to keep the taping to very short periods of time.

r:
> Might be a good idea to keep the taping to very short periods of time.

Well, on the other hand, I'd only have one apnea.
Of course, it would last all night.