Question about FF vs Nasal Mask Pressures

[dutchbrown]

Ok, I'm a relatively new CPAP user... been struggling to find the right mask, loved the comfort gel except for mouth leakage (esp when nasally congested), so got the Quattro FF mask....

Now, my data has changed from mask to mask, but the only one that doesn't necessarily make sense is the pressure change (my Mseries is current set on Auto)

Nasal:
Leak ~30 (normal)
Pressure ~9.5-10 cmH2O

FF:
Leak ~39 (normal)
Pressure ~11-11.5

Why would the pressure go up? I'm assuming the CPAP machine adjusts for flow rate and pressure... and I can't find data on the mask pressure drop anywhere (I know there is a pressure drop along every portion from CPAP machine to back of throat, but I don't know if it's minuscule, or what?). I'm trying to figure out if the FF mask has a larger pressure drop from hose to back of throat, if the increased pressure is just due to nasal congestion, or a combination of both... or another reason entirely?

Oh, and one other thing I changed was moving the CPAP machine from a shelf even with the bed to on the floor about 2 feet below. I wouldn't think it would make that much difference, but??? suppose anything is possible.

Thoughts? (from practical experience or theory?)

[jules]

My experience ------ crude of course

Swift - I need 8.5

CL2 simple cushion - I need 10

then I got an APAP -

I tend to use 8 - 10 to try to cover all my mask needs since I found that would cover the Swift and CL2 I was using - it worked fine with Optilife (I hated that mask), Soyala Nasal, Somnoplus

Somnoplus - I tend to run it 8 - 10 - some nights I don't get to 10 for long with this mask and 9.5 worked well as a single pressure for the 2 nights I used the old machine


BUT

Soyala FFM - BEATS ME !!!!!!!!!!! - I haven't found a suitable range with it. I have tried 8 - 10 - nope - 8 - 12 nope - I still have some more homework to do

[Wulfman]

Ok, I'm a relatively new CPAP user... been struggling to find the right mask, loved the comfort gel except for mouth leakage (esp when nasally congested), so got the Quattro FF mask....

Now, my data has changed from mask to mask, but the only one that doesn't necessarily make sense is the pressure change (my Mseries is current set on Auto)

Nasal:
Leak ~30 (normal)
Pressure ~9.5-10 cmH2O

FF:
Leak ~39 (normal)
Pressure ~11-11.5

Why would the pressure go up? I'm assuming the CPAP machine adjusts for flow rate and pressure... and I can't find data on the mask pressure drop anywhere (I know there is a pressure drop along every portion from CPAP machine to back of throat, but I don't know if it's minuscule, or what?). I'm trying to figure out if the FF mask has a larger pressure drop from hose to back of throat, if the increased pressure is just due to nasal congestion, or a combination of both... or another reason entirely?

Oh, and one other thing I changed was moving the CPAP machine from a shelf even with the bed to on the floor about 2 feet below. I wouldn't think it would make that much difference, but??? suppose anything is possible.

Thoughts? (from practical experience or theory?)

Without actually looking at your reports, it's a little more difficult......

Have you done the "Teflon tape trick" to the elbow on your Quattro mask?
My leak rate at a constant pressure of 12 on that mask (without taping) was about 39. WITH the Teflon tape, it's about 31.
I'm THINKING the machine is compensating for that leakage difference between 30 and 39 and that's why you're seeing higher numbers. If you were to set it at a constant pressure of something like 11 cm. the machine wouldn't have to bump up the listed pressure, but would keep the pressure constant at 11 (with automatic leak compensation)......in other words, the pressure would still be 11, but the machine may be actually be pumping more air to keep up with the difference in leakage.

You also didn't say how long of a period of time you're comparing......IF you also had extra events during the night(s) on the Quattro, that would account for the increase in pressure. This is really an "apples and oranges" situation with different masks and on an Auto. Too many variables from night to night and mask to mask to make determinations.

Den

[Wulfman]

By the way, DutchBrown......Did you have Stephen McNally's character in mind when you picked your forum name?

http://www.imdb.com/title/tt0043137/

That move was on TV this last weekend.

Den

[dutchbrown]

By the way, DutchBrown......Did you have Stephen McNally's character in mind when you picked your forum name?

http://www.imdb.com/title/tt0043137/

That move was on TV this last weekend.

Den

LOL no, that's been my moniker on online forums since... well, since there WERE online forums back in BBS days. Dutch was a nickname from way back, and Brown is my last name.

Didn't even know a movie character existed with that name. Cool to know.

[dutchbrown]

Without actually looking at your reports, it's a little more difficult......

Have you done the "Teflon tape trick" to the elbow on your Quattro mask?
My leak rate at a constant pressure of 12 on that mask (without taping) was about 39. WITH the Teflon tape, it's about 31.
I'm THINKING the machine is compensating for that leakage difference between 30 and 39 and that's why you're seeing higher numbers. If you were to set it at a constant pressure of something like 11 cm. the machine wouldn't have to bump up the listed pressure, but would keep the pressure constant at 11 (with automatic leak compensation)......in other words, the pressure would still be 11, but the machine may be actually be pumping more air to keep up with the difference in leakage.

You also didn't say how long of a period of time you're comparing......IF you also had extra events during the night(s) on the Quattro, that would account for the increase in pressure. This is really an "apples and oranges" situation with different masks and on an Auto. Too many variables from night to night and mask to mask to make determinations.

Den

The period of time was about a week with the comfort gel and about 3 days with the Quattro. the numbers were fairly consistent tho, no outliers that I could tell (at least without my card scanner I'm waiting for). AHI about the same (actually a little lower with the Quattro just because I don't mouth leak). The other difference was that I was stuffed up a bit using the Quattro (the whole reason I got a FF mask, to use when I'm stuffed up).

Question with the teflon tape trick... does that at the bottom swivel junction that is dark tan (just above where the hose attaches), or the elbow junction into the mask?

Thanks!
Jeremy

[Wulfman]

You pop the elbow from out of the front of the mask and also pull the hose connector off of it, too. Wrap BOTH ends of the elbow and then put it back together. About 4 wraps with the tape seemed to do pretty well on mine. It makes it a little stiff for awhile, but eventually loosens up a bit. You should definitely see a drop in your leak data.

Den

[sleepie]

bump---because i find the answer by jules interesting---i was wondering this same question---i keep trying to go to a full face mask---from a nasel mask--and my numbers suffer---but my machine is set---12---13.5---most of the night its topped out at 14----i am going to try leaving the top number 20,,,and see what happens--thanks to jules and all---if any other thoughts please post----pat

[Wulfman]

bump---because i find the answer by jules interesting---i was wondering this same question---i keep trying to go to a full face mask---from a nasel mask--and my numbers suffer---but my machine is set---12---13.5---most of the night its topped out at 14----i am going to try leaving the top number 20,,,and see what happens--thanks to jules and all---if any other thoughts please post----pat

Sleepie,

WHICH full face mask? That in itself can make a huge difference. If you're trying to use something like the Hybrid, with its higher vent flow (leak) rate, that would (in my opinion) be causing a pressure increase. And, in general, many of the full face masks have a higher vent flow rate than some of the various nasal masks.

Den

[dutchbrown]

Ok, I did the teflon tape fix to my Quattro FF last night. My leak rate dropped by ~5, and my 90% pressure dropped by about .8cm (from 11.1 to 10.3).

So... it seems that leak rate DOES impact the pressure settings, and effectively, the mask you use seems to effect the pressure you need to run at. After doing some research, most machines do handle flow rate and pressure independently... however, they can only control those at the machine. The pressure drop of the hose... and more importantly, the mask... effects the pressure the back of your throat actually sees. It seems that, at least in my case with my specific masks, the leak rate/mask configuration causes a not-insignificant change in the pressure needed at the machine. (I would think the pressure needed at the back of my throat is somewhat stable, and I have seen this over the course of the last couple weeks.)

Interesting info... and I would think that if anyone has a non-auto CPAP and has changed masks since being set for a pressure, you might want to consider getting retested or retitrating your pressure in auto setting.

(FYI, I am not a DR, but I am a mechanical engineer that deals in automation in the manufacture medical devices... just not CPAP related equipment... but a pressure drop makes sense according to fluid dynamics theory... I just didn't know without a lot of math work and data how severe the pressure drop would be, whether it would be significant... but it makes sense that it's significant due to the fact that it is very low pressure to start with. One other interesting note: if the pressure drops are that significant due to the mask "architecture", you could assume that just hose design and position - i.e. number and severity of bends, rises, drops, etc - could also have a not-insignificant impact to pressure settings.)

[Wulfman]

Ok, I did the teflon tape fix to my Quattro FF last night. My leak rate dropped by ~5, and my 90% pressure dropped by about .8cm (from 11.1 to 10.3).

So... it seems that leak rate DOES impact the pressure settings, and effectively, the mask you use seems to effect the pressure you need to run at. After doing some research, most machines do handle flow rate and pressure independently... however, they can only control those at the machine. The pressure drop of the hose... and more importantly, the mask... effects the pressure the back of your throat actually sees. It seems that, at least in my case with my specific masks, the leak rate/mask configuration causes a not-insignificant change in the pressure needed at the machine. (I would think the pressure needed at the back of my throat is somewhat stable, and I have seen this over the course of the last couple weeks.)

Interesting info... and I would think that if anyone has a non-auto CPAP and has changed masks since being set for a pressure, you might want to consider getting retested or retitrating your pressure in auto setting.

(FYI, I am not a DR, but I am a mechanical engineer that deals in automation in the manufacture medical devices... just not CPAP related equipment... but a pressure drop makes sense according to fluid dynamics theory... I just didn't know without a lot of math work and data how severe the pressure drop would be, whether it would be significant... but it makes sense that it's significant due to the fact that it is very low pressure to start with. One other interesting note: if the pressure drops are that significant due to the mask "architecture", you could assume that just hose design and position - i.e. number and severity of bends, rises, drops, etc - could also have a not-insignificant impact to pressure settings.)

IF a person has a data-capable (straight-pressure) CPAP machine and the software, they should be able to find out. The CPAP machine/mode will deliver a constant pressure to the mask (not counting for large leakages). However an APAP, if it's starting at a lower pressure will usually wait to respond to events (leaks, flow limitations, snores, hypopneas and apneas).
Consequently, there are some things a person needs to take into consideration when comparing the data from the different machines/modes.
Also, how many of us do NOT have variations from one night to the next?

Den

[sleepie]

i have used the large ultra mirage ff mask--the flexi-fit 431--the quattro--and now i'm trying the ultra mirage med ff mask---after looking at the #'s for a trend---i see that everytime i strap on a ff mask my numbers go up---always up---after reading this ,,i printed the pressure charts--for approx 6 days of ff mask usage---and what do i find---i'm spending more time at the machine high setting----i will know more tomorrow--if i hear this right,,i will leave to top pressure at max 20---to see what happens to the #'s----this really has been driving me crazy--i don't want to tape or glue my mouth--would rather just wear the ff mask for those mouth drops-----pat