Leak rates .vs. machine limitations

[ywp]

I am confused here. My resp. M apap manual specification list a maximum flow of 35 LPM

I will see if I can paste the quote
Pressure Stability:
<10.0 cm H2O (±0.5 cm H2O)
≥10.0 to 20.0 cm H2O (±1.0 cm H2O)
Measured in accordance with EN ISO 17510-1 @ 1/3, 2/3, and Pmax with BPM set to 10, 15,
and 20 BPM @ 20° C (±5° C), 50% RH (±5%), and an atmospheric pressure of 101.54 kPascals.
Maximum Flow: 35 LPM
Measured in accordance with EN ISO 17510-1 @ 1/3, 2/3, and Pmax with BPM set to 10, 15,
and 20 BPM @ 23° C (±2° C), 50% RH (±5%), and an atmospheric pressure of 101.54 kPascals

I talked to a res med person about the quatro FF mask has an intended leak rate of 36.6 @ 10, 43.5 @ 14, and 47@ 16.

I have been using my auto at a 10 to 15 setting. On my very best looking reports I have a average leak rate of 37 with no large leaks. on the longer summary I have aaverage leak of 37, 90%leak of 44 and max of 82.

Sounds like my resporonics lacks the volume "horse power" to drive this mask?

Does other brands have more volume capacity

Am I missing some important concept
For reasons to long to mention I can only use a FF masks and the quatro fits best.

[DreamStalker]

Is your pressure stability stats from your APAP machine ... cuz you have a CPAP listed under your profile.

If it is for your APAP, I'm guessing that the 35 LPM is the limit for the APAP sensor that feeds input into the APAP algorithm. That would explain why masks with large leak rates don't do well in APAP mode. In order for APAP algorithm to function correctly, it needs to have a fairly sensitive response to flow ... the higher the flow rate (ie. leak rate) the less sensitive it becomes.

I could never get a full face mask to work in APAP mode ... FF masks only worked well for me in CPAP mode.

I'm sure the more knowledgeable will chime in and give their views ... Snoredog?, DSM?

[ywp]

Yes it is off my apap. I need to update my profile.

Do you know what these blowers can output?

Do other brands of blowers have the same limitations?

When you say you have not been able to get a apap to work on a full face. What or how did it not "work" How did it fail?

I am dumb founded to hear an auto may not work with a full mask. What options does a full face user have.

Does a bi-pap have two blowers in use. And higher sensors /volume?

Thanks

[Goofproof]

I would say the machine specs are the correct specs. The mask makers don't worry about the machines, they worry about profits from selling masks. I never tried that mask or the hybrid because I could read that with their leak rate they weren't designed for our leaf blowers. I use a "Classic Tank" and I find that using any thing that I can't keep the LPM under 40, changes my treatment results. I imagine the "M"eries wouldn't out blow mine.

I am currently using a extremely poorly made in China ComfortGel Nasal mask, and am having a hard time getting the LPM under 41 @ 15 cm. Most runs of the same mask come in at 35 to 37 LPM @ 15 cm. I can feel the difference as it blows the covers off and also blows in my eyes.

As it still on the working edge of my treatment, I've let it go, but if it was any poorer, I would seal off part of the vent. (I've Done it before)

Bi-PAP used to go to 35 CM, now the cheaper they can make them the more cash for them. The 24 volt models had motors in them.... Jim

[ozij]

Auto machine makers will always say their machines only work work with their own masks - they only check their own masks.

The quattro is a Resmed mask. Resmed masks usually have higher vent flow rates than other companies' masks at a given pressure (look here for a comparison of many masks http://www.internetage.com/cpapinfo/leak-rates-1.html

Respironics' own full face masks reach 40 lpm at about 20 cm h2o (comfort full 2 here: http://www.respironics.com/UserGuides/1 ... tFull2.pdf).

I don't know enough physics to interpret those machine data, but FWIW, I do know that volume and flow are not the same.

O.

[jnk]

I think ozij nailed that answer perfectly.

The job of an auto is to react. If it seems yours isn't reacting properly, it may be worth trying another similar mask with different properties. But it is a nebulous area in practice. One person may have snore and flow limitations that a particular auto would have no trouble reacting to regardless of the intentional leak of the mask being used, whereas another person may find that the auto is not picking up on what's happening with their using the exact same mask and machine. Too many variables to factor in to give a broad rule-of-thumb answer for your situation. Bottom line is whether your machine seems to be working with your sleep/breathing profile with your mask. Personally, I'd rather love my mask and lock down the pressure on the auto than change masks, so I see the dilemma.

[DreamStalker]

Volume and flow rate are not the same .... one is a volume (ie liters, cubic inches, gallons, etc.) and the other is a rate of air flow (ie. volume per unit time).

As I tried to make clear before, the machine may well be able to output the flow rate to successfully maintain the needed pressure (different from both flow rate and volume as it is a force per unit area) while still allowing for the mask leak rate.

The problem may be that the machine air flow sensor which is used to feed data to the APAP algorithm is not sensitive enough to sense the subtle changes in one's breathing to properly adjust the flow rate to increase or decrease the correct pressure. That is because as air flow increases, the relative amount of air flow changes due to breathing decreases.

So again, the machine may well be able to maintain the proper pressure for a high vent flow mask rate in CPAP mode .... just don't expect the APAP algorithm to work correctly at high ventflow rates.

[Wulfman]

I am confused here. My resp. M apap manual specification list a maximum flow of 35 LPM

I will see if I can paste the quote
Pressure Stability:
<10.0 cm H2O (±0.5 cm H2O)
≥10.0 to 20.0 cm H2O (±1.0 cm H2O)
Measured in accordance with EN ISO 17510-1 @ 1/3, 2/3, and Pmax with BPM set to 10, 15,
and 20 BPM @ 20° C (±5° C), 50% RH (±5%), and an atmospheric pressure of 101.54 kPascals.
Maximum Flow: 35 LPM
Measured in accordance with EN ISO 17510-1 @ 1/3, 2/3, and Pmax with BPM set to 10, 15,
and 20 BPM @ 23° C (±2° C), 50% RH (±5%), and an atmospheric pressure of 101.54 kPascals

I talked to a res med person about the quatro FF mask has an intended leak rate of 36.6 @ 10, 43.5 @ 14, and 47@ 16.

I have been using my auto at a 10 to 15 setting. On my very best looking reports I have a average leak rate of 37 with no large leaks. on the longer summary I have aaverage leak of 37, 90%leak of 44 and max of 82.

Sounds like my resporonics lacks the volume "horse power" to drive this mask?

Does other brands have more volume capacity

Am I missing some important concept
For reasons to long to mention I can only use a FF masks and the quatro fits best.

If you do a search on the items I've bolded, you'll get some of these links:

http://www.iso.org/iso/iso_catalogue/ca ... mber=41615

http://www.techstreet.com/cgi-bin/detai ... id=1528217

http://www.saiglobal.com/shop/script/de ... 00013_4807

http://www.standardsdirect.org/standard ... 19229.html

Basically, and without paying hundreds of dollars for the documentation to SEE the "standards", I'm interpreting that what they're saying in what you clipped out of the manual is that they're meeting (or exceeding) International Standards Organization specifications.

I think you're trying to compare "apples and oranges".

If my flow generators "work" and give me the results that make me feel better......THAT'S ALL I care about.

Den

[sepool]

I was curious about the same thing last August. Since then I found a British care standard document:

http://fp.artpweb2.f9.co.uk/files/ARTP/ ... t%2008.pdf

This leads me to believe that the 35 LPM figure is the maximum unintentional leak rate that can be compensated for. In other words, it is the variation in flow (over and beyond the intentional, steady mask leak rate) during which the above figures of pressure stability must be maintained.

So, if the desired pressure is 20 cmH2O, with a mask leak rate of say 40 LPM, the pressure must remain within 1 or 2 cmH20 of 20, even if the flow rate varies from 5 to 75 LPM. (40 +- 35). I think I remember Respironics auto track technology states that the auto track works even during leaks like this. Like the above poster, I don't worry about mine if I feel OK, and if my leaks don't go over 35 LPM over my base line leak. You also have to remember your base line leak rises as the auto pressure rises.

[Snoredog]

35LPM @20 cm "Pressure" is a lot of flow at maximum pressure.

IF your leak exceeds 75L/m the machine will stop responding to events, any scoring seen will be inaccurate and if a Remstar it will drop pressure by 2 cm after 1.5 minutes and continue to drop pressure until leak is resolved.

These are flow-based machines, if they monitor they monitor changes seen to the volume of that flow and changes seen on the pressure signal.

It doesn't matter if you have twin-turbo impellers the volume of air you can get out of the machine is limited by the inside diameter of the delivery hose, which is what 22mm? Same on Respironics, Resmed, PB, F&P, DeVilbis etc. They only way one would have greater flow is by using a higher pressure and well that ain't gonna happen.

So if machine A, B & C are compared, if all are limited to 20 cm pressure, they will be delivering the same volume flow determined by the delivery hose dimension.

[sepool]

I agree with Snoredog.

In the above link document, here is:

4.0 Flow
Maximum flow is measured as free flow from the outlet of the device.
90 L.min-1 at 6.5 hPa/cmH2O (1/3 max pressure)
135 L.min-1 at 13 hPa/cmH2O (2/3 max pressure)
165 L.min-1 at 20 hPa/cmH2O (max pressure)

Because of the tubing limitations, you can only have higher flow at higher pressures. But see how much flow these machines are capable of. 35 L.min-1 is for the measurement of pressure stability, not the limit of what the machines can provide.

[-SWS]

The following are all given as volume-based flow rates in the same LPM unit of measurement:

SPEC ONE (machine related):

I am confused here. My resp. M apap manual specification list a maximum flow of 35 LPM
Maximum Flow: 35 LPM

This specification speaks of machine-sourced flow capability, irrespective of human respiratory effort. Here we're simply measuring apples that can be sourced by the machine (specifically when the machine is hooked up to a basic reference circuit as opposed to those "free flow" measurements sepol cites above). We're also not factoring in oranges that can be provided by the human diaphragm with this spec.

SPEC TWO (mask related):

I talked to a res med person about the quatro FF mask has an intended leak rate of 36.6 @ 10, 43.5 @ 14, and 47@ 16...
Sounds like my resporonics lacks the volume "horse power" to drive this mask?

This leak rate speaks of combined flow that would be sourced by both the machine and the human diaphragm---but specifically that combined flow which will be missing or leaking away from the circuit through the mask orifices. So here we're measuring all missing apples and all missing oranges combined (the mask's designed leak rate---with not one, but two contributing flow sources when the circuit is in nightly use).

In summary spec one above is how much flow the machine will produce when hooked up to a reference circuit; spec two is how much flow will be lost through the mask orifices when that mask is hooked up to both human and machine. Your APAP has enough horsepower to use any CPAP mask.

[ywp]

I am a mechanic, designer and installer of water pumps and air blowers. My cpap theraphy is not "" working"" "" And I probably over fixate on mechanics and logic.

Thank you for the though full replies. And please do not take this personally

But What goes out must come in. Maximum output = Maximum input. Not Maximin output + leak rate + lung effort + hope - denial = real out put.
You guys maybe right about it being a limitation on sensors for control and data. Maybe a velocity problem, laminare flow ? . Sounds like the blower has the "horse power" or performance. Guess that is what I will assume. Good explanation to keep an auto pap locked down to a narrow range or go back to cpap. Does make it harder to trust the data

Just mad at medical community

[ractar28]

What about your therapy "isn't working"?

The quattro ffm has a grid for intentional leak. I'm not suggesting you mess with them, but is it not possible to lower the intentional leak rate by blocking one or more of the holes in that grid? Likewise, the hybrid uses a series of exhaust holes (instead of a single hole), so the same should be possible there, right?

Are you using an apap with c-flex or a-flex or neither? Perhaps one of the "comfort" settings would help with your issues if it's an issue of comfort vs pressure.

[jnk]

I am a mechanic, designer and installer of water pumps and air blowers. My cpap theraphy is not "" working"" "" And I probably over fixate on mechanics and logic.

Thank you for the though full replies. And please do not take this personally

But What goes out must come in. Maximum output = Maximum input. Not Maximin output + leak rate + lung effort + hope - denial = real out put.
You guys maybe right about it being a limitation on sensors for control and data. Maybe a velocity problem, laminare flow ? . Sounds like the blower has the "horse power" or performance. Guess that is what I will assume. Good explanation to keep an auto pap locked down to a narrow range or go back to cpap. Does make it harder to trust the data

Just mad at medical community

Don't worry about over-fixating. It all has to make sense to you for you to be comfortable with it.

But you may be over-complicating and missing the larger picture in some small ways.

Generally, any mask should work well enough on any machine, with only a few rare exceptions, and that is true regardless of the specs of the flow generator. So matching masks to machines isn't usually a problem. That is because there is no motivation for a mask manufacturer to make a mask that machines can't use. So, basically, use the mask you like best. If your leak is under control (unintentional/bad kind) and your AHI numbers are OK, then you are good.

It is true that when it comes to autos, too much leak out of a mask, intentional or unintentional, can make the auto's job harder as far as picking up what's going on in your throat. But if you, like most people, have common types of snore and flow limitations that the auto is able to pick up on, it should still do its thing regardless of the mask. Again, the only way to know for sure that it is doing its thing in by looking at the AHI reports, which you can trust as long you don't have too much unintentional/bad leak.

At least, that's how I understand it.

That being said, my personal, very unpopular, view is that it doesn't hurt to try the masks of an auto's manufacturer first.

But the key point is as -SWS said:

Your APAP has enough horsepower to use any CPAP mask.