UARS: A Critical Link to Optimizing PAP Therapy Results

[ozij]

[quote="mindy"]Ok folks, I still feel rather ignorant about BiPAP Vs APAP ... although I feel I've been learning a lot reading this thread.

My APAP has A-Flex and C-flex so I do get pressure relief at exhalation. Do I understand correctly that this pressure relief is not the same as the BiPAP? I gather that other than setting the A-Flex or C-Flex relief at 1, 2 or 3, I cannot specifiy a specific pressure to use on exhalation. Is that the key difference? That it's not possible to set a specific exhalation pressure as with a BiPAP? Or am I missing something else????

Thanks!
Mindy

[mindy]

Thanks yet again, Ozij!

Now I think I "get it" - at least on the 30,000-foot level!

m

[khvn]

Whoa! Rested Gal, the Dream Queen of cpaptalk.com, came thru finally, one more time...

They need to make a sticky out of this piece of writing of yours--anyone still foggy about how bilevels work needs to read it. For me, that's exactly what I need to quench my thirst--cold logic, hard numbers, easy to understant.

But, we're still not out of the wood! Not just yet... (ok, you can stop sighing and rolling up your eyes now)

As you have indicated it yourselve, your comparo is only between basic bilevel and basic APAP. All hell will break loose if someone throws in these monkey wrenches with "EPR", "C-Flex", "A-Flex" labels on them.

All I'm saying is if these sophisticated Flex features are are getting better and better at playing the variable pressure game (as in the case of A-Flex), who needs to pay more for bilevels?

[Wulfman]

I've tried to stay out of this thread as much as possible because I've never used a bi-level machine and don't consider myself particularly knowledgeable about them. (Which hopefully keeps me from putting my foot in my mouth)
However, as I've read these posts (to some degree), I've noticed an absence in the discussion of the higher pressures required for some patients.....which the bi-levels deliver (some to 25 cm. and some to 30 cm.).....as compared to the max pressure of 20 cm. from the CPAPs and APAPs. In those circumstances, the greater exhale relief offered by bi-level would be a HUGE benefit for the user......especially in the area of "comfort".
Also, it seems that a number of users who suffer from aerophagia seem to benefit more from bi-level therapy as opposed to APAP or CPAP therapy.

It seems to me that none of these machines are necessarily the "magic bullet" for all categories of this therapy, but each of the developed technologies that are provided by the various manufacturers (and some in very specialized machines) can fill a particular niche and be of help to CERTAIN users, once their specialized need is determined.

Den (Happy as can be with his single-pressure w/C-Flex therapy)

[rested gal]

As you have indicated it yourselve, your comparo is only between basic bilevel and basic APAP. All hell will break loose if someone throws in these monkey wrenches with "EPR", "C-Flex", "A-Flex" labels on them.

All I'm saying is if these sophisticated Flex features are are getting better and better at playing the variable pressure game (as in the case of A-Flex), who needs to pay more for bilevels?

'Cause none of those exhalation relief features in a cpap or a bipap can make those machines operate exactly like a bilevel machine.

Those features can give some relief, some comfort, when exhaling, but they don't make those machines deliver treatment in the same way a true bilevel machine does.

That's not saying that bilevel is THE best treatment for everyone. I don't think Dr. Krakow said that either. Snoredog's post summed up extremely well what Dr. Krakow was pointing out.

There's a vast difference between someone who absolutely needs to use a bilevel machine for good treatment or needs a bilevel even to be able to do treatment at all, and someone who simply likes using a bilevel for comfort reasons.

I use a BiPAP Auto machine purely for comfort. I don't "need" that kind of treatment machine at all. I just like the naturalness of the feel of breathing with it better than any other machine I've tried.

So, yeah, if a person:

1. is comfortable breathing out with whatever machine they are using...

2. doesn't need a bilevel machine for a specific condition...

3. is feeling well rested...

... then there's no compelling reason to ditch the machine they're using and switch to a bilevel machine.

Dr. Krakow's points have also included that "feeling good" is relative to how one felt before. If flow limitations remained after titration, perhaps one could feel even better if those were addressed.

What machine, what pressures, etc., to address flow limitations with would be a very individualized thing. A lot depends on what showed up in a person's sleep study. And what shows up is very dependent on what's being looked for in the first place, who's doing the looking... and what kind of data gathering thingies are being used to do the lookin'.

[BarryKrakowMD]

You guys and gals are nailing it. Thanks for all your integrative threads; they're very well written and clarifying...at least I imagine for most readers!

Regarding expiratory relief, I think it's pertinent (to some extent) to view it as "bilevel-like" but as I tried to make clear previously, the gap with EPR seems only to be equivalent to 2 cm of water. And, in our clinical experience, the typical gap of bilevel we use is 4 to 5 range. So, as stated, EPR might look like bilevel but it doesn't function to yield the necessary gap, assuming the gap you need is greater than say, 3.

I keep forgetting to mention that on the home page of my website http://www.sleeptreatment.com, I already have up a picture of normal airflow on bilevel. In the videos, click the tab "Lectures." About 10 seconds in on the 2nd and 4th Power Point slides, there's a 30 sec epoch of REM sleep. You can hit pause and still get a decent image. On the sensor marked CPAP Flow (it's really bilevel), you will see the well rounded curves on the top portion (inspiration) and bottom portion (expiration).

I should have a better/bigger graphic next week.

[khvn]

What machine, what pressures, etc., to address flow limitations with would be a very individualized thing. A lot depends on what showed up in a person's sleep study. And what shows up is very dependent on what's being looked for in the first place, who's doing the looking... and what kind of data gathering thingies are being used to do the lookin'.

Ok, let's see how Rested Gal use her bilevel in this simplified hypothetical scenario:

RG needs a minimum of 8 cmH2O to keep her AHI under 3 so she has no choice but set her EPAP at 8. On inhaling, RG feels fine at 14 so she sets her IPAP at 14.

Tell me if I'm wrong, but RG doesn't really need that bilevel. She can actually accomplish the same thing (keeping her AHI under 3) with a good ol' classic straight-shooter CPAP set at 8 cmH2O!?

[krousseau]

C-O-M-F-O-R-T

Your argument could be correct but it is irrelevant. Rested Gal already said

I use a BiPAP Auto machine purely for comfort. I don't "need" that kind of treatment machine at all. I just like the naturalness of the feel of breathing with it better than any other machine I've tried.

Faced with the choice between changing one's mind and proving that there is no need to do so, almost everyone gets busy on the proof.....Galbraith's Law

[bmab]

1. Rested gal-Did the bipap reduce your runs or flow limitations?

2. Dr K-I understand the concept of spirometry where different lung conditions have different patterns of breathing ie pulmonary fibrosis, COAD, asthma etc. I guess it is important to breath normally and despite the good AHI etc, my breathing pattern may still be sick. I think your point of breathing normally is very attractive to me. Is that info on your slide showing the normal breathing pattern actually available on the bipap machine data and can you tweak the machine easily at home to get to a normal looking breath pattern? Anyway the discomfort of the pap when sleeping longer ie from 6 to 8 hrs per night would make me consider a bipap in the future. Funny the resmed vantage is actually like a bipap but only able to offer up to 3cm relief for expiration.

[Wulfman]

1. Rested gal-Did the bipap reduce your runs or flow limitations?

2. Dr K-I understand the concept of spirometry where different lung conditions have different patterns of breathing ie pulmonary fibrosis, COAD, asthma etc. I guess it is important to breath normally and despite the good AHI etc, my breathing pattern may still be sick. I think your point of breathing normally is very attractive to me. Is that info on your slide showing the normal breathing pattern actually available on the bipap machine data and can you tweak the machine easily at home to get to a normal looking breath pattern? Anyway the discomfort of the pap when sleeping longer ie from 6 to 8 hrs per night would make me consider a bipap in the future. Funny the resmed vantage is actually like a bipap but only able to offer up to 3cm relief for expiration.

The Vantage only has EPR available in single-pressure (CPAP) mode and therefore ends up being the same as the Elite (CPAP).

Den

[khvn]

What machine, what pressures, etc., to address flow limitations with would be a very individualized thing. A lot depends on what showed up in a person's sleep study. And what shows up is very dependent on what's being looked for in the first place, who's doing the looking... and what kind of data gathering thingies are being used to do the lookin'.

Ok, let's see how Rested Gal use her bilevel in this simplified hypothetical scenario:

RG needs a minimum of 8 cmH2O to keep her AHI under 3 so she has no choice but set her EPAP at 8. On inhaling, RG feels fine at 14 so she sets her IPAP at 14.

Tell me if I'm wrong, but RG doesn't really need that bilevel. She can actually accomplish the same thing (keeping her AHI under 3) with a good ol' classic straight-shooter CPAP set at 8 cmH2O!?

[rested gal]

An odd thing... you know how so many of us have thought EPR at "3", for a drop of 3 cms when breathing out with a resmed cpap (or Vantage in cpap mode) would "feel like" a bilevel machine set for a 3 cm difference between IPAP/EPAP?

Well, I used the resmed Elite CPAP several nights in a row recently. I set EPR at "3" for a 3 cm drop. Pressure set at 10. Every time I breathed out, I kept wondering, "WHY is there such a feeling of resistance each time I exhale? A 3 cm drop in pressure should definitely feel comfortable breathing out. WHY does it feel like breathing out against the same pressure still, every time I start to exhale?"

Then I began paying very close attention to the sound of the Elite's motor as I breathed in and out. Not the mask exhaust sounds. The sound of the motor itself.

The motor sounds like it starts to wind down at the beginning of the exhalation and continues to "move down" in sound at least through the halfway point of my exhalation.

So, I don't believe resmed's EPR gives its full drop at once. I think no matter whether you have EPR set for the least drop ("1" for 1 cm) or the most drop ( "3" for 3 cms) it simply starts to lower the pressure just a fraction of a cm when you start to exhale and continues the dropping process well into the exhalation. I don't think it finally reaches whatever drop you've set it for until past the middle of a person's exhalation. At least that's what it sounds like the motor is doing and that's the resistant "feeling" it gives me. A feeling of a lot of resistance at the beginning of each exhalation.

That may be why each time I've tried comparing the "feel" of EPR to the feel of a bilevel machine set for same amount of drop, they haven't felt one bit alike. Even in a "blind" test I did not so long ago, where I enlisted my sister to switch the hose back and forth from machine to machine for me (to my mask) and had a room fan turned on so I couldn't hear any machine sounds.

C-Flex, even though it is not an exact "cm" drop, actually feels more like bilevel relief (to me) than EPR does. C-flex gives most of its drop during the beginning of the exhalation, when most people would probably prefer to get pressure relief for breathing out -- to get the exhalation started easily.

Even funnier (in an odd way) is this: I also used my 420E for several nights after using the Elite. Had the minimum pressure set at 10 on the 420E, which is where that machine pretty much stays for me most of the night.

Even the very first breath breathing out with the 420E felt like there was more "give" to the start of each exhalation...less resistance to breathing out... than when using EPR at "3" with the Elite cpap. The 420E was much more comfortable to me for breathing out. Go figure.

So, I started wondering about that! WHY would a machine with no "exhalation pressure relief" feature at all feel like it was giving so much more "exhalation relief" than EPR set for an exact 3 cm drop?

I vaguely recall someone ( -SWS, perhaps ) writing on the message board a long time ago....something about either the material the PB machines' blower fan blades are made of, or something about the flexibility of tips of the blades....something to do with the blower. And how that probably would give some degree of relief for breathing out. Wish I could remember or find it.

I keep thinking it had to do with the tips of the blades. Anyway, it was something about the material and/or the design of the 420E's blades actually giving a softening at the beginning of each exhalation, even though there is no "advertised" exhalation relief feature in the PB 420E autopap.

All I know is that EPR (which I'd have expected to be very close to the comfort of a bilevel) doesn't seem to deliver much drop at the beginning and doesn't make breathing out comfortable at all to me.

Respironics' C-Flex, and even the Puritan Bennett with no advertised "feature" for exhalation relief, both make breathing out feel much less resistant to me than trying to breathe out using resmed's EPR. The only thing better comfort-wise for breathing out that I've used are bilevel machines.

[rested gal]

So, if my titrated pressure is 16 cmH2O. The tech guy sets my straight-shooter CPAP machine at, like it or not, 16, and send me home. However, since I'm a fancy dude with my own fancy bilevel at home so I get to set my own EPAP the way I want it. But, lo and behold, I end up set it at the exact same 16 also!

A titration for bilevel in a sleep lab is conducted quite differently from how a titration for straight cpap goes.

As far as I know, the EPAP in a bilevel machine is set for preventing apneas. Just apneas.

I may not understand this next quite right, and I may be stating it poorly...

The way I understand it: If some pressure can keep a throat from completely collapsing during exhalation, voila'...there's no apnea. But it takes more pressure to hold the throat FULLY open for inhaling. Fully open, as in not even a partial collapse (a hypopnea) to interfere with inhaling. If the EPAP pressure is set "just high enough" (some pressure) to keep the throat open during exhalation AND during any pause at the end of exhaling, inhalation can start again. EPAP has done its duty. The person can then actually start to inhale. The greater inhale pressure (IPAP) in a bilevel would kick in the instant the person starts to inhale, and then IPAP will do its job. IPAP's job (for inhalation purposes) is just what "straight cpap" does...keep the throat well and truly open to let you draw in a full breath.

As I understand it, in a sleep lab titration aimed specifically for putting a person on a bilevel machine (not a cpap titration), BOTH pressures (EPAP and IPAP) are set the same to start with. BOTH are raised together during the first part of the titration... 5/5 6/6 7/7 and so on...UNTIL apneas disappear.

When the apneas disappear, that pressure is noted as the EPAP pressure. EPAP is left there (say at a pressure of " 8 " ). The titration process continues, but this time raising only the other pressure...the IPAP pressure. Proceeding 9/8 10/8 11/8 12/8 etc., The person keeps breathing out at 8 cm with no apneas happening, and the IPAP is raised until there are no more hypopneas, and ideally no more flow limitations or residual snores. The higher IPAP pressure is now keeping the throat open for inhaling, just like the lower EPAP pressure is keeping it open for exhaling.

Seriously, I find it very difficult to exhale against 16 But dare I set my bilevel's EPAP lower than my required minimum of 16!? I can't believe it, for starting pressure, my fancy bilevel can't do me anything fancier than that humble CPAP!

Read the red paragraph again to see why I think the lower EPAP pressure has just one job to do and can easily do its job if set "just high enough" to prevent collapse during exhale. Keeping the throat open well enough so the person can get inhale started again. IPAP (set higher) handles the other job...preventing collapse when you breathe in.

A sleep lab titration to find the correct single level of cpap pressure to handle EVERYTHING at once is very different from a sleep lab bilevel titration aimed at finding two separate pressures that have two distinctly separate jobs to do.

[mindy]

RG,

Thanks very much, RG! I think I'm beginning to understand a little more from your insightful posts and others, too.

On a more global level, I suspect that the point KHVN is missing is that we all have different comfort levels and sensitivities (and probably different breathing patterns and processes). If it were a "one solution fits all" as I believe he suggests, then one would expect that one mask would work for all -- and that just isn't realistic. I'm grateful that we have multiple choices even though too many (including me) don't fully understand what that means. At a guess (Dr Krakow I'd appreciate a comment on this) I would think that just as people are different, that there is probably not a single pattern for SDB or even for sleep apnea. And thus it takes different technologies to cover the range both for comfort and for effective therapy.

m

[Ms Piggy]

Thank you to Dr. Krakow and forum members and guests for the explanatory posts on this subject. I am so pleased to get all this information, yet to be fully digested as to how it relates to me. I have been worrying about the number of runs/flow restrictions vis a vis return of headaches and feeling "foggy". Sleep Dr. says any problems due to other causes not OSA, a big decision made on the small amount of info he has actually looked at.
My runs for the last 13 days were 3050 or 3310 depending which report - Detailed or Pressure on my, year old, PB420E which is set at 6-10, uses mostly 6 with approx quarter at 7 and an odd short time at 8 & 9, tritrated pressure 7. AHI below 5 and leak rate ok too.

A request for tritration next year seems to be indicated, I now know that I will have to decide what type of machine it should be for. In the meantime I need to work out what changes I can make NOW to reduce the flow restrictions. BUT with RG's comment, as below, I recognise that will not be easy to do alone or with "professional' help. Will check out Dr. K's site today.

from RG
Dr. Krakow's points have also included that "feeling good" is relative to how one felt before. If flow limitations remained after titration, perhaps one could feel even better if those were addressed.

What machine, what pressures, etc., to address flow limitations with would be a very individualized thing. A lot depends on what showed up in a person's sleep study. And what shows up is very dependent on what's being looked for in the first place, who's doing the looking... and what kind of data gathering thingies are being used to do the lookin'. Smile
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