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[Pressure] pressure difference full face to nasal mask
#1
pressure difference full face to nasal mask
Hello fellow Sleepiheads!

I`ve been on CPAP for 3 weeks now and slowly getting used to the treatment of additional o2. I got a S9 Autoset running at a pressure setting of 4 – 14 cmH2O . I`ve started off with a full face mask Quattro FX but it did not fit properly around my nose and it leaked badly. Next I`ve tried the Mirage Quattro full face mask, very comfortable to wear and easily drifting off to sleep, but since I`m not used to sleep on my back I woke up after approx. 1.5 h and could not go back to sleep unless I`ve turned on to my belly. That in turn caused leaks again since the mask was pushed sideways by the pillow.

3 night ago I’ve turned to the P10 air pillow nose mask and I finally can sleep laying on my belly without disrupting the mask! I also could sleep much longer than with a full face mask and I think the P10 is “my” mask!

The one thing I`ve noticed on sleepyhead is that the pressure with the full face mask hoovers at around 7 – 12 cmH2O and with the P10 only at around 5-8 cmH2O (I`ve changed the machine settings to nasal mask) AHI is unchanged at around 1.0

Is the lower pressure in the nature of the nasal mask or may this be because I do lay on my belly thereby helping my airways to stay open?

Thanks in advance for your advice

Dom
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#2
RE: pressure difference full face to nasal mask
Hi XDom321,
WELCOME! to the forum.!
Hang in there for answers to your questions and much success to you with your CPAP therapy.
trish6hundred
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#3
RE: pressure difference full face to nasal mask
I have had similar experience when I moved from a f10 FFM to a P10 nasal pillows mask.

It is explained by laws of physics -
1) pressure drops when a fluid has to bend (in FFM it's a 90 degree bend from elbow to nose).
2) the additional dead space in FFM also reduces the nasal delivered pressure a bit.

Also there is a physiological difference. The pressure needed to eliminate apnea while mouth breathing is higher than pressure needed to nose breathe exclusively. With a P10, if you can successfully keep your mouth shut, your pressure need will be lesser.

A nasal mask will perform somewhere between a FFM and a nasal pillow mask.

This need for less pressure makes the case for P10 nasal pillows more compelling (in addition to less leaks and better exhaust diffusion in P10).

Everyone will ultimately use the P10. La résistance est futile Smile

PRS1 Auto & Dreamstation Auto w/ P10 and straight pressure of 8cm
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#4
RE: pressure difference full face to nasal mask
Thank you all for your feedback!Thanks

AshSF`s explanation makes sense and explains the pressure difference quite well. Just woke up from another 6 hours of sleep, I haven`t experienced the “WOW” effect yet, but its early days. I also am getting better and better handling all the additional gear I need going to bed.

Have a great day and be the force with your CPAP machineSleep-well

Dom
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#5
RE: pressure difference full face to nasal mask
(04-14-2015, 02:22 PM)AshSF Wrote: It is explained by laws of physics -
1) pressure drops when a fluid has to bend (in FFM it's a 90 degree bend from elbow to nose).
2) the additional dead space in FFM also reduces the nasal delivered pressure a bit.

With the scale of pressures, flow rates, and size of the passages in CPAP, the above effects are totally insignificant for CPAP usage.

A FFM pushes on your lower jaw. Some people say this can push back on the jaw, narrowing the size of the airway at the back of your throat and leading to more severe apnea and requiring more pressure. The idea is sound, but I haven't seen any "orthodox" medical studies and papers.

Many people do find they have more apnea or need more pressure with a FFM mask.
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#6
RE: pressure difference full face to nasal mask
Dom,

That has been my experience regarding using the cloth nasal mask vs. a full face mask. Recently, when I was limited to a full face mask after a septoplasty, I had to run pressures of at least 14/10 to even keep the AHI under 10. If I ran it higher, I obtained leaks. With the nasal mask, I can run pressures at around 11.4/7.4 and get an AHI of around 1. This discrepancy was true even before my Septoplasty as an FYI.

In my case, I suspect that due to having a hard time with fitting a full face mask, I have had to severely tighten the straps to avoid leaks which I don't have to do with the cloth mask. As a result, the theory on the ffm pushing back the jaw would make sense in my case.

Now maybe if I ever found a FFM that fit, I would have a different experience, who knows. But I am not going to be engaging in that experiment. Smile
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#7
RE: pressure difference full face to nasal mask
(04-15-2015, 03:42 AM)49er Wrote: Dom,

That has been my experience regarding using the cloth nasal mask vs. a full face mask. Recently, when I was limited to a full face mask after a septoplasty, I had to run pressures of at least 14/10 to even keep the AHI under 10. If I ran it higher, I obtained leaks. With the nasal mask, I can run pressures at around 11.4/7.4 and get an AHI of around 1. This discrepancy was true even before my Septoplasty as an FYI.

In my case, I suspect that due to having a hard time with fitting a full face mask, I have had to severely tighten the straps to avoid leaks which I don't have to do with the cloth mask. As a result, the theory on the ffm pushing back the jaw would make sense in my case.

Now maybe if I ever found a FFM that fit, I would have a different experience, who knows. But I am not going to be engaging in that experiment. Smile

I also had to tighten the ffm very tight, it also may explain the pressure difference between nasal and ffm. Anyhow, I currently am quite happy with my p10, hopefully the CACP treatment soon will show some results.
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#8
RE: pressure difference full face to nasal mask
I went from 10-15 on the ffm to 7-9 on the nasal pillow. Had to do that the first night. Couldn't exhale against the nasal pillow at the 10-15 range. Might be a tighter exhaust vent on the nasal pillow too. AHI had been 8-10 on the ffm even at the higher pressure, it's running 1-3 on the nasal pillow at the lower pressure. Most of my events were CA though. The ffm was just more disruptive for me.
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#9
RE: pressure difference full face to nasal mask
I just noticed your post. I posted the exact opposite question about an hour ago.

I couldn't adjust to the P10(pillow) after 8 weeks. So now I'm trying the F10(full). I can sleep better but my AHI numbers are worse and I don't feel well rested when I get up.

I'm thinking my pressure needs to go up, especially after the replies you have.
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#10
RE: pressure difference full face to nasal mask
(04-14-2015, 11:45 AM)XDom321 Wrote: Hello fellow Sleepiheads!

I`ve been on CPAP for 3 weeks now and slowly getting used to the treatment of additional o2. I got a S9 Autoset running at a pressure setting of 4 – 14 cmH2O . I`ve started off with a full face mask Quattro FX but it did not fit properly around my nose and it leaked badly. Next I`ve tried the Mirage Quattro full face mask, very comfortable to wear and easily drifting off to sleep, but since I`m not used to sleep on my back I woke up after approx. 1.5 h and could not go back to sleep unless I`ve turned on to my belly. That in turn caused leaks again since the mask was pushed sideways by the pillow.

3 night ago I’ve turned to the P10 air pillow nose mask and I finally can sleep laying on my belly without disrupting the mask! I also could sleep much longer than with a full face mask and I think the P10 is “my” mask!

The one thing I`ve noticed on sleepyhead is that the pressure with the full face mask hoovers at around 7 – 12 cmH2O and with the P10 only at around 5-8 cmH2O (I`ve changed the machine settings to nasal mask) AHI is unchanged at around 1.0

Is the lower pressure in the nature of the nasal mask or may this be because I do lay on my belly thereby helping my airways to stay open?

Thanks in advance for your advice

Dom

It is a mistake to compare different nights when on CPAP let alone compare different masks on different nights. Every PAP'er knows we have 365 sleeps per year rather than a year of 365 sleeps, & every sleep is different & produces different results in Sleepyhead. That said, since nasal pillows masks don't leak & full face mask do, perhaps the machine is adjusting pressure to offset this.
Pascal's Principle states that pressure in a confined space is transmitted undiminished in all directions, so curves, bends etc will make no difference. In Apnoea the obstruction is in the lower airway and both the nasal & oral passages are connected to this airway. Thus the only contributing factor to the phenomenon you're experiencing has to be mask leaks.
[Image: signature.png]Keep on breathin'
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