Different Masks, WAY different results!

[potholerepairman]

PotHoleRepairman, EasyBreathe is not the same thing as the EPR (expiration pressure relief) function.

Thanks , very true, sore throat got my brain today .Ill walk away from the keyboard.

[DoninOrlando]

Komodo,
I have the exact same results as you with the exact same masks. I am trying to make the Quattro work. It is fairly comfortable for me and I am tired of tape, chinstraps, etc, that I need to use with any nasal or pillows. My other mask is the comfortgel nasal. If I use it, with tape, etc, I usually get low leaks, and AHI around 5-6. With the Quattro my AHI has been anywhere from 20-40. I just switched from a med to lge Quattro as I thought that may be causing leaks. I wanted more room for my mouth to move. I know my jaw drops and I can only assume that is causing leaks in my sleep when relaxed. My AHI is always low for the first 2 hours. Perhaps in REM I am more relaxed and drop my jaw? But I cannot figure out any other reason to explain the high AHI on Quattro. I did try increasing pressure from 10 to 11 or 12 but it only increased leaks and made me tighten the mask too much. I use a buckwheat pillow and adjust my face and mask until it seems in a firm supported position that shouldn't change when asleep.
By the way, when my AHI is high around 20-40 with Quattro, my H's is usually less than 1. When my AHI is low like around 5, the H's are 2-3 and A's are 2-3. Kind of strange. The higher my AHI, the greater percentage are Apneas, and when lower, the Hypopneas hoes up. I assume at lower numbers the Cpap is catching more H's before they grow up into full blown Apneas ? Makes sense right? I also get similar results to Quattro with UMFF and similar to comfortgel nasal with Mirage Swift LT.

[Slinky]

WHY walk away from the keyboard, PotHoleRepairman??? I've certainly made worse-er bloopers than that in the forum for God and everybody to see!!!

For instance, in this thread alone I failed to clarify: my nasal cushion mask that I like and use w/the chin strap is one of Respironics' oldest masks, the Simplicity simple nasal cushion. The Simplicity simple nasal cushion has the very small inlet hose coming off the mask as does the Breeze mentioned below.

Does the VPAP machine work with a Breeze mask?

It can, but some of the features may be affected. The Breeze system has a very small inlet hose, which creates very high resistance to flow. This high resistance can cause the mask alarm, Smart/Start/Stop feature, and compliance data functions to be compromised. The treatment pressure (at the mask) may also be slightly less. If none of these features are important to the user or clinician, then the effect is unimportant.

The above is from an interesting chat transcript w/a Resmed Rep at talkaboutsleep.com

http://www.talkaboutsleep.com/sleep-dis ... hat.htm#44

Frankly, I could care less about and do NOT use the Mask Alarm, SmartStart/Stop feature and I sure as hell don't care about the frigging compliance data!!! I just can't help but wonder if the Resmed Rep didn't misspeak himself and actually meant Efficacy Data instead of compliance data?? It certainly would explain A LOT, at least in MY situation between the Simplicity nasal and the Zzz-Mask full face.

It would also explain WHY I felt no difference between the Simplicity and the Swift LT for Her but did between the Simplicity and the OptiLife nasal cradle.

[potholerepairman]

WHY walk away from the keyboard, PotHoleRepairman??? I've certainly made worse-er bloopers than that in the forum for God and everybody to see!!!

thanks,Would not trust myself to pour cereal into a bowl of milk ,or the other way around.Got the presick not going to get sick eyes floating backwards and up while trying to close at the same time feeling.All this without taking the strange meds the pharmacist keeps behind the counter and I am not qualified to answer paper or plastic. mask on.

[Slinky]

Erg!!! Sure am sorry to hear that!!! I hope it passes quickly!

[gasp]

Thanks a lot for the links Velbor.

I completelly agree with the fact the smaller diameter of the Swift LT hose compared to the Activa mask hose is the responsible of the increasing on my HAI. The cpap pressure sensor is located inside the machine, so the machine should be seeing all the way the same pressure but we at the end of the mask we are receiving a lesser pressure not able to keep our air ways opened enough so we FEEL and LIVE the difference.

It could be too that part of the air is going into my stomach instead of my lungs, today I had again air in my stomach. I used to have that problem with the Activa but it had stoped.

Now I need to convince the md to make something with my pressure :0(, but I will need to suffer a couple of days to have the prove.

Rosacer

I have only had air in my stomach a few times, it's called aerophagia, but when it did happen - ouch! If you were like me, there was visible proof that air was trapped in my stomach. My stomach protruded and it sounded hollow. And of course it hurt. If this is true for you, couldn't you show it to your doctor - or get another doctor that believes you?

[Velbor]

.... the smaller diameter of the Swift LT hose compared to the Activa mask hose is the responsible of the increasing on my HAI. The cpap pressure sensor is located inside the machine, so the machine should be seeing all the way the same pressure but we at the end of the mask we are receiving a lesser pressure not able to keep our air ways opened ....

This is a troubling conclusion to reach. It implies that the engineers at ResMed have not done their jobs. Whatever other issues we may have with ResMed (particularly in marketing contexts), the quality of their engineering has never been a cause for concern. My own evaluation is that they are among the brightest stars in the industry (which may be a feeble compliment).

It is true that a constriction in an air conduit may cause turbulence, a drop in airflow velocity (though never a drop in airflow volume) and an increase in pressure. IF this is happening at the entrance to the Swift hose, and IF the machine sensors read what is happening at this point as the pressure delivered at the user's face, then there is trouble indeed. The question is, given the airflow volume, the pressures involved, and the relative diameters and amount of "constriction", will this situation result? Did the ResMed engineers miss so significant an issue? And is that the way aerodynamics works? I am forced to doubt it.

There are many CPAP configurations with apparently marked "constrictions" in the main line. Right-angle adaptors. "Bacterial filters." Humidifier chamber entry ports with anti-backwash inserts. Anti-asphyxia valve systems in full-face masks. And the "narrower" tubing of the Swift hose. If any of these caused a significant and "permanent" pressure node which the machine sensors could not "see past," there would be problems indeed. It is so easy to independently test and confirm mask pressure independently (by the designers, and during polysomnograms), that it is hard for me to believe that this is a real issue.

(I am reminded, if I remember correctly, that older Puritan Bennett machines utilized a separate pressure sensor tube from machine to mask paralleling the main tubing, and that older ResMed machines utilized a separate pressure sensor tube to bypass the humidifier. ResMed no longer uses this system, and I think that PB/Covidien has moved away from this approach as well. Neither of these would pick up a "mask-tubing" pressure anomaly in any case. Presumably these approaches have been found to be unnecessary, and no other manufacturer seems to find them necessary.)

In summary, though I am not in a position to offer hydrodynamic data, I have to doubt that the Swift is so badly engineered that pressure issues related to tubing diameter such as you have proposed are the root cause of the changes in respiratory event indices you have noted. There are most certainly differences in efficacy between different masks (or mask types), even those which do not offer "flow constriction" explanations. I crave explanations, but I'd rather go without any than accept easy once which are likely inaccurate.

Thanks for drawing attention to the REAL issue of mask-related efficacy variability. Best of luck finding a combination that works for you. Velbor

[Slinky]

Velbor, I believe that that is why Resmed has the Mask Selection feature. This is from a chat transcript at talkabout sleep with a Resmed Rep:

Does the VPAP machine work with a Breeze mask?

It can, but some of the features may be affected. The Breeze system has a very small inlet hose, which creates very high resistance to flow. This high resistance can cause the mask alarm, Smart/Start/Stop feature, and compliance data functions to be compromised. The treatment pressure (at the mask) may also be slightly less. If none of these features are important to the user or clinician, then the effect is unimportant.

I believe, tho I can't substantiate it, that the Resmed Rep misspoke himself and meant Efficacy Data instead of Compliance Data.

The full transcript can be found at:

http://www.talkaboutsleep.com/sleep-dis ... hat.htm#49

[SleepingUgly]

My AHI and pressures went up when I switched from the Swift LT to the Quattro.

[Muse-Inc]

...tried breathing through just my nose as if I was wearing the Nasal mask. Fine. Then, with my mouth slightly open, and things were still fine. THEN, I tried with my mouth full open, and my jaw slightly back, as if I was wearing the FFM. WOW! Wowowowowow!!!! There was a HUGE difference in the amount of air I was able to easily inhale!

I just tried that (can any one one wearing a FFM resist?) and had the same experience! Just tilting my chin down creates the same restriction...now I know why KiraLynx loves her St Bernard 'fix' . Thank goodness, my Hybrid does not pull my jaw back, so I'm 'safe'...well, something anyway .

[timbalionguy]

It is true that a constriction in an air conduit may cause turbulence, a drop in airflow velocity (though never a drop in airflow volume) and an increase in pressure. IF this is happening at the entrance to the Swift hose, and IF the machine sensors read what is happening at this point as the pressure delivered at the user's face, then there is trouble indeed. The question is, given the airflow volume, the pressures involved, and the relative diameters and amount of "constriction", will this situation result? Did the ResMed engineers miss so significant an issue? And is that the way aerodynamics works? I am forced to doubt it.

Assuming constant mass flow, the pressure drops and the velocity increases in a constriction. This is called the Venturi effect. You can actually pull a pretty good vacuum in a properly designed venturi. In a normal CPAP system though, the machine has a very definite 'source impedance' in the blower system. Although the venturi effect will increase the flow rate in the vicinity of the restriction, the restriction overall creates a 'resistance' to the mass flow. There will be less 'pressure drop' across the 'source impedance' of the machine. And if not otherwise corrected by the machine, this will cause the pressure at the machine (and all the way to the restriction) to increase. On the other side of the restriction, the pressure increases, but not to what it was before the restriction. The 'resistance' of the restriction will have turned some of the pressure- and flow-energy into heat (not enough to notice or easily measure, though). The overall mass-flow will be less.

The bottom line is that most machines are assuming that there is little loss between the machine and the patient. Although in my limited experience, the modern systems are very forgiving, the less restrictions in the hose/mask system, the more responsive the machine will be to therapy need changes.

[Muse-Inc]

...Assuming constant mass flow, the pressure drops and the velocity increases in a constriction. This is called the Venturi effect...

Ahh, see CPAP air in terms of fluid dynamics...images of eddies in water thru rock filled areas. Yup, makes sense. Amazing pieces of technology these xPAPs!

[ozij]

The question is, given the airflow volume, the pressures involved, and the relative diameters and amount of "constriction", will this situation result? Did the ResMed engineers miss so significant an issue? And is that the way aerodynamics works? I am forced to doubt it.

I am ready to bet both my tin foil and organic straw hats that the Resmed comment about the Breeze was created by Resmed PR before Resmed engineers came out with a nasal pillows mask. And I'm also pretty sure the PR person did not mis-speak himself because bald statments about efficacy would have sent PB to check them, and disprove the statement. The chat was there to sell the nifty new features of the Resmed machine.


O.

[potholerepairman]

My AHI and pressures went up when I switched from the Swift LT to the Quattro.

Mine too , and oddly think I feel better with the quattro while asleep, not when watching tv, reading, waking with marks ,or looking at number but when actually asleep.

[rosacer]

Thank you timbalionguy for your nice explanation on hydraulics, I loved it. My brain is still at low speed and I didn't remember all the concepts you presented in the explanation.

I need to say that I'm not acusing the Resmed ingeneers of inconpetence. I acknowledge they have created very good products but hey are simply human beings and as humans they are not perfect. I can't stop suspecting there is a problem with pressure.

The other thing is each person is different and the variations in pressure that will affect somebody's treatment ill not be perceived by another one. So there are limits in the optimization of products. Ex. the machine doesn't read a leak if it doesn't go to a certain level, they determined the point where they stops reading and that's inderstandable and normal.

So I can't say the ingeneers are infaillible in a design. In the design of a mask there are more than mechanical and fluid mechanics essues to take in consideration. There is the computer's side too, don't forguet we have a small computer there with a software, etc.

Something is clear to me, there is an essue hide somewere affecting us. A product can be good but not excelent in everyway for everyone. I doesn't means in any way the product is no good!

I hope I will be able to get used to the Swift, all the rest is unrelevant. It don't really matters to me who is right or who is wrong here.