Difficulty tolerating low pressure with nasal but not full

[FrederickRose]

I can't tolerate PAP lower than 7cm H2O via nasal mask (tried N20, P10, DreamWear) but have no problem whatsoever tolerating PAP as low as 4 cm H2O with a full face mask (F&P Simplus).

I know it's common to feel like one isn't getting enough air when PAP pressure is low (like 4-5 cm H2O), but is that a nasal mask only thing?

I was thinking that my nasal resistance is very high (chronic allergies, etc) and that I can only breath comfortably exclusively through my nose when I crank the pressure up some. Whereas the full face mask lets me do the combination nose-mouth breathing I've been doing all these years, so I can tolerate the low pressures there.

Or maybe it's that the full face mask has the anti-asphyxia valve which lets me bring in more air?

[ChicagoGranny]

Or maybe it's that the full face mask has the anti-asphyxia valve which lets me bring in more air?

That valve is closed when the machine is running.

[FrederickRose]

So in my case, the difference must be my stuffy nose?

[Wulfman...]

I can't tolerate PAP lower than 7cm H2O via nasal mask (tried N20, P10, DreamWear) but have no problem whatsoever tolerating PAP as low as 4 cm H2O with a full face mask (F&P Simplus).

I know it's common to feel like one isn't getting enough air when PAP pressure is low (like 4-5 cm H2O), but is that a nasal mask only thing?

My hypothesis is that my nasal resistance is very high (chronic allergies, etc) and that I can only breath comfortably exclusively through my nose when I crank the pressure up some. Whereas the full face mask lets me do the combination nose-mouth breathing I've been doing all these years, so I can tolerate the low pressures there.

Or maybe it's that the full face mask has the anti-asphyxia valve which lets me bring in more air?

Why don't you just increase your minimum pressure?
Are you using Sleepyhead software? Look to see where your pressures are going and what the average minimum is.
I don't think I could breathe with a pressure less than 10 cm.


Den

.

[FrederickRose]

I did increase my min pressure. Actually have it at 17 right now.

Was just trying to understand why it's so easy for me to tolerate low pressures with full face mask and not nasal.

[Pugsy]

It's more a potential volume or air space thing. Full face masks allow more air movement or at least perceived air movement because of the volume.
Sometimes a small change in volume can make a big difference and sometimes a person needs a lot more volume.
Like some people might find going up a size in a nasal pillow is all the change they need and others simply need more air movement via more pressure.
We won't suffocate at 4 cm with a Small nasal pillow or cushion but it can sure feel like it.

[FrederickRose]

Makes sense, thanks, Pugsy.

[TedVPAP]

I did increase my min pressure. Actually have it at 17 right now.

Was just trying to understand why it's so easy for me to tolerate low pressures with full face mask and not nasal.

Now I am very confused. The original post was about breathing comfort being impacted by mask type while at the minimum pressure of 4 or 5 and now you state your minimum pressure is set to 17. Is 17 a typo? Did you mean 7?

[Wulfman...]

I did increase my min pressure. Actually have it at 17 right now.

Was just trying to understand why it's so easy for me to tolerate low pressures with full face mask and not nasal.

Now I am very confused. The original post was about breathing comfort being impacted by mask type while at the minimum pressure of 4 or 5 and now you state your minimum pressure is set to 17. Is 17 a typo? Did you mean 7?

I guess you're not the only one, Ted.
That has had me scratching my head since it was posted.


Den

.

[Pugsy]

He's DIYing things and trying to see what his OSA might be at rock bottom pressure settings.
He's a doctor. Self diagnosed without official sleep study (home or lab) as of yet....I don't think.
From what I have see of the rock bottom pressure reports...not much question as to the diagnosis. They are pretty ugly.
He's just experimenting.

[Wulfman...]

He's DIYing things and trying to see what his OSA might be at rock bottom pressure settings.
He's a doctor. Self diagnosed without official sleep study (home or lab) as of yet....I don't think.
From what I have see of the rock bottom pressure reports...not much question as to the diagnosis. They are pretty ugly.
He's just experimenting.

Okie Dokie!


Den

.

[TedVPAP]

He's DIYing things and trying to see what his OSA might be at rock bottom pressure settings.
He's a doctor. Self diagnosed without official sleep study (home or lab) as of yet....I don't think.
From what I have see of the rock bottom pressure reports...not much question as to the diagnosis. They are pretty ugly.
He's just experimenting.

Thanks for clarifying.
So the 17 is a direct answer to a direct question, but totally superfluous to the topic of the thread.

Regarding the OP's original post, I also have more difficulty breathing via nose instead of mouth but I love using pillows - just turn it up. Different air paths can have different resistance. R1>>R2. The effective resistance of two parallel resistors is Reff = (R1+R2)/(R1*R2). So when R2<<R1, the effective resistance < R1.

[ChicagoGranny]

So in my case, the difference must be my stuffy nose?

There seem to be too many individual variables - anatomy, sleeping habits, psychology, how the masks are worn - to give a definitive answer.

Why don't you get something done about the chronic stuffy nose? A consultation with an ENT - allergy testing and treatment, possibly surgical correction of nasal problems such as deviated septum, enlarged turbinates, sinus problems.

[FrederickRose]

Thanks for clarifying.
So the 17 is a direct answer to a direct question, but totally superfluous to the topic of the thread.

Yes. Without having had a proper sleep study, I've experimentally determined that I need a min EPAP of 17 in order to consistently have a machine-read AHI of consistently less than 5.

Then because I was second guessing the diagnosis, I took my pressure all the way down to 4 to see how ugly my SleepyHead download would look. From prior experience, I knew I wouldn't tolerate a pressure of 4 using my usual nasal masks, but I tried a full face mask out of curiosity (and because I had a cold with nasal congestion) and was surprised to find that I had no problem tolerating CPAP 4 with the full face mask.

Out of purely "academic" curiosity, I posed the question here to start the thread. So when I was advised to try a higher pressure, I replied that I do usually use a pressure of 17. Sorry I wasn't clearer to begin with.

Self diagnosed without official sleep study (home or lab) as of yet....I don't think.

I recently did Jason's type 2 home sleep study (AXG Sleep Diagnostics) and am awaiting the report. Unfortunately I didn't sleep very much on the night of the study. I was worried about the wires falling off or the battery failing and just kept waking up and having a hard time falling asleep. Hopefully I slept enough to get an official diagnosis!

[FrederickRose]

So in my case, the difference must be my stuffy nose?

There seem to be too many individual variables - anatomy, sleeping habits, psychology, how the masks are worn - to give a definitive answer.

Why don't you get something done about the chronic stuffy nose? A consultation with an ENT - allergy testing and treatment, possibly surgical correction of nasal problems such as deviated septum, enlarged turbinates, sinus problems.

Thanks, that is good advice. I've had seasonal allergies all my life. As a kid I had surgery for nasal polyps and turbinates. I have a feeling that if I were to just use my Flonase like I should, that it would get a ton better. I'm going to give that a try, and if it doesn't work, I'll see someone.