UARS: A Critical Link to Optimizing PAP Therapy Results

That would be "rested GAL" not "rested girl". She looks all grown to me.

I have been following this thread with interest but I can't honestly say any light bulb has gone off yet. Anything in this thread that will help the treatment of the average cpap head who has the typical apap machine???? If so, please point me to it. Thanks.

BadBreath wrote:

khvn wrote:The low pressure setting (EPAP) in a bilevel is there for patient's comfort and does absolutely nothing to improve OSA treatment. At worst, it can even represent a weak spot that risks airway collapse. As such, for treating OSA, bilevels possess nothing more special or better than APAPs or even straight CPAPs.

Fortunately for me (and my sucessful treatment) your overly broad statement is wrong. I was prescribed a bi-level machine from the start for a very important reason. With straight cpap, when the required pressure was reached for eliminating episodes during inhalation it was too strong for my exhalation and would result in central apneas. For this reason no successful tritration using cpap was possible. But with a bi-level I am able to use the required inhalation pressure and a lower yet adequate exhalation pressure that stops events without causing central apneas.

Can the bi-level go to too low of a pressure to support the airway? Yes, if the lower range is set too low. I previously used the example where a lower recommended pressure allowed increased hypopneas, whereas returning it to the previous low setting eliminated them. The machine will not go lower than allowed, so will not create a threat of airway collapse if set correctly.

And if you think patient comfort has nothing to do with improving OSA treatment then you really know nothing about it and are probably not a user of any kind of cpap.

At this point, I'm reminded of the proverbial tale of Nasrudin when he lost his key and scoured the grounds outside his home in search of it. When a neighbor offered to help, the search continued unabated until his friend inquired, "Where did you lose the key?" Nasrudin calmly replied, "Inside my house." To which his exasperated friend asked, "So, why are we searching out here?" "Because," exclaimed Nasrudin, "there's more light."

I'm extremely impressed how nearly all of you are searching inside the house...

We've got 5 abstracts on deadline to finish this weekend for the annual sleep conference in June, so I don't know yet if I can post again til Monday. I still owe you comments on the "quantitative paradox," and some more "bilevel tips."

Rest Wishes,

P.S. I have not found the 425 data useful, but admit I might be missing something.

BarryKrakowMD wrote:We've got 5 abstracts on deadline to finish this weekend for the annual sleep conference in June, so I don't know yet if I can post again til Monday. I still owe you comments on the "quantitative paradox," and some more "bilevel tips."

Dr Krakow, once again I'd like to thank you for all your posts so far. Its been very valuable information that you have shared with us. Thanks for sticking with us as I realize internet forums can be a harsh sometimes. Be assured that some of us are very greatful for your presence here. I wish more people in the profession where willing to participate.

Good luck on those abstracts

Thanks, -james

James, Harsh Environment??? Greedy for info too-we won't let you forget the quantitive paradox-or the bilevel tips.

Mckooi, thank you for your overly kind words. But no, I was not anywhere smart enough to figure out what was going on with the drastic pressure increases the 420E autopap was using for me at first. It was an autopap, btw... not the bipap auto I'm using now.

I'd never have figured it out on my own. I just kept raising the maximum pressure setting more and more, thinking since the machine was going up there, I must actually need that.

It was an extremely intelligent man who posts on this message board by the nickname -SWS who took one glance at some 420E data reports I sent him, and suggested I turn off the setting called "FL" (IFL1). After that, the machine worked perfectly to treat me well and no longer took off up into the stratosphere of high pressures with me.

It was -SWS, not me, who was smart enough (and understood the 420E well enough even though he had never even touched a 420E at that time!) who figured it out. He understood flow limitations. I didn't.

Snoredog wrote:My interpretation of Dr. K's message:

I don't think that was Dr. K's message to put bi-level against any other type of therapy, his message as I understand it was derived from his expertise and experience was to remain open with the thought of FL's playing a role in residual fatigue after your OSA has been traditionally treated (i.e. <AHI=5).

He also suggests Bi-level therapy as opposed to CPAP or AutoPAP for elimination of those FL's, he also suggests that spontaneous arousals seen on PSG's of the past may not truly be spontaneous. He suggests that some labs (especially if PSG was performed years ago) may not be able or sensitive enough to "detect" those FL events (in order to correlate them to what we know as "spontaneous" arousals as seen on our PSG).

---snipped ---

All Dr. K is suggesting is that we remain open to the thought of UARS (Upper Airway Resistance Syndrome) as a contributing factor to residual daytime fatigue when we are fully compliant with CPAP.

This is NOT a battle between which machine is best, he shared his expertise on one particular aspect of SDB and I for one appreciate his suggestions.

He doesn't suggest everyone run out and purchase a Bi-level, and Bi-level is not for everyone. In many cases Bi-level can adversely impact your treatment.

I think you nailed it, Snoredog!!

Great post!

Snoredog wrote: Dr. K's the first one to say "look at it this way.." and for that I appreciate him stopping by.

Ditto the appreciation!

I have been following this thread with interest but I can't honestly say any light bulb has gone off yet. Anything in this thread that will help the treatment of the average cpap head who has the typical apap machine???? If so, please point me to it. Thanks.

I noticed you are using Resmed.I used resmed apap too for 3 years and its software did not show me any runs. I am taking my 2 daughters to Japan Disneyland next week and I bought my pb420e 1 week ago as a travel device and it showed me all the runs.

Please refer to rested gal previous post with the overnight sleep data showing lots of runs. By reducing the runs to about half after tweaking with the various settings, I am feeling a lot better and thanks to Dr K once again.

Interestingly when I tweaked my machine trying to reduce the runs, increasing the upper pressure does not seem to help and by making the machine more sensitive to runs by turning off the FL1 also did not help much. The right setting and the right gradient seemed to matter. Hence a bipap may be even better for me.

If you have a specific interest in somthing like the anxiety/SDB cycle or PTSD buy it. I think the anxiety/SDB interaction warrants at the very least checking it out at the library. Dr B.K. makes it relevant for all of us.
If you are collecting books it is essential.
PS I did not find Dr. Dement's book that helpful-except as an Ambien substitute.

khvn wrote: Strictly for OSA treatment, bilevels are NOT better than APAPs

I will once again stress that patient comfort is critical to the successful treatment of OSA, and your insistence on dismissing it doesn’t make it any less true. If someone removes their mask (either consciously or unconsciously) due to a feeling of suffocation on exhale, the result is that the treatment has failed.

I think you a choosing to not fully comprehend my point in order to maintain your argument (although I’m pretty sure repeatedly claiming skepticism and disbelief without stating a factual reason isn’t any kind of argument).

The bi-level machine is treating my OSA, just without causing the additional events that the straight cpap did due to the inability to exhale against the inhalation pressure. If you can accept that point, it is the same point made by Dr. Krakow concerning flow limitations or (UARS) caused by high pressure at exhalation. It is the same effect, just a different degree of event. Because my response resulted in an apnea a bi-level was scripted, but he believes a resulting UARS should be treated as just as important and be treated the same way.

khvn wrote: Did they fully explain to you why they set you up with a bilevel and not an APAP (I'm highly skeptical that APAP algorithm can't handle your unique EPAP requirement)?

In spite of the fact that I think I have a relatively good sleep doctor, at no point did anyone explain anything about the machine itself or the reasons for its choice. In fact, six months ago I didn’t know the difference between cpap and a pap smear. So I readily admit my understanding can be limited and incorrect. Through my own research what I have come to understand is that the bi-level, unlike the auto, is designed to recognize and supply different levels for inhale and exhale as well as recognize the transitions between. That means it can anticipate and more quickly and accurately respond to the actual conditions, including, as Rested Gal pointed out, the pause at the end of exhale. And if you can narrow the range to meet the specific needs of each, it is even more responsive. I know this from direct experience, and I don’t believe the auto could do the same as effectively. Or more simply put, I would rather be able to tell the machine just what I need to prevent events than wait until an event happens that to which it can then respond.


Troll or not, your skepticism has provoked a good discussion that I think can help all cpap users better understand the different treatments and their appropriate uses, so I thank you.

I love this forum, and this thread is particularly meaningful to me.

The doctor’s last post made me smile because just yesterday, I was reminded of Diogenes, who in ancient times searched the streets of Athens with a lantern looking for an honest man. (He never found one.)

Unfortunately, my OSA experience has been just like that. In my search for answers, all I’ve run into are healthcare professionals who are either uninformed, unwilling to share what they know, or uninterested in pursuing the truth.

At last, I think I’ve found an honest man! Dr. Krakow’s contributions and clear explanations, while stirring, have given me insight into the frequent arousals I experience with CPAP therapy. His book is on my Christmas list.

At the same time, I feel for KHVN, who apparently has been tooled as much as I have by an inept healthcare delivery system and ineffective, inconsistent standards of care for OSA sufferers.

BadBreath wrote:

khvn wrote: Strictly for OSA treatment, bilevels are NOT better than APAPs

I will once again stress that patient comfort is critical to the successful treatment of OSA, and your insistence on dismissing it doesn’t make it any less true. If someone removes their mask (either consciously or unconsciously) due to a feeling of suffocation on exhale, the result is that the treatment has failed.

I think you a choosing to not fully comprehend my point in order to maintain your argument (although I’m pretty sure repeatedly claiming skepticism and disbelief without stating a factual reason isn’t any kind of argument).

The bi-level machine is treating my OSA, just without causing the additional events that the straight cpap did due to the inability to exhale against the inhalation pressure. If you can accept that point, it is the same point made by Dr. Krakow concerning flow limitations or (UARS) caused by high pressure at exhalation. It is the same effect, just a different degree of event. Because my response resulted in an apnea a bi-level was scripted, but he believes a resulting UARS should be treated as just as important and be treated the same way.

khvn wrote: Did they fully explain to you why they set you up with a bilevel and not an APAP (I'm highly skeptical that APAP algorithm can't handle your unique EPAP requirement)?

In spite of the fact that I think I have a relatively good sleep doctor, at no point did anyone explain anything about the machine itself or the reasons for its choice. In fact, six months ago I didn’t know the difference between cpap and a pap smear. So I readily admit my understanding can be limited and incorrect. Through my own research what I have come to understand is that the bi-level, unlike the auto, is designed to recognize and supply different levels for inhale and exhale as well as recognize the transitions between. That means it can anticipate and more quickly and accurately respond to the actual conditions, including, as Rested Gal pointed out, the pause at the end of exhale. And if you can narrow the range to meet the specific needs of each, it is even more responsive. I know this from direct experience, and I don’t believe the auto could do the same as effectively. Or more simply put, I would rather be able to tell the machine just what I need to prevent events than wait until an event happens that to which it can then respond.


Troll or not, your skepticism has provoked a good discussion that I think can help all cpap users better understand the different treatments and their appropriate uses, so I thank you.

BadBreath wrote:I will once again stress that patient comfort is critical to the successful treatment of OSA, and your insistence on dismissing it doesn’t make it any less true. If someone removes their mask (either consciously or unconsciously) due to a feeling of suffocation on exhale, the result is that the treatment has failed.

khvn, please re-read what BB said... notice especially the words: "on exhale."

khvn wrote:Now, I can do the exact same thing with my clunky APAP at home.

No, you can't do the exact same thing (settings-wise) with an APAP as with a Bilevel machine. Or vice versa. They are very different from each other.

Forget features like C-flex, A-flex, Bi-Flex, or the BiPAP auto, etc. for the moment. Just concentrate on the differences between how a basic autopap and a basic bi-level ("bipap") work.

khvn wrote:Couple of pushes and, voila, I got my LO and HI pressures set up nicely.

"LO" (the "minimum" pressure setting in an autopap) and EPAP (the minimum pressure that will be used when you exhale) in a bilevel machine cannot be equated. Which is what it looks like you're thinking.

Those two types of machines operate completely differently from each other.

A basic autopap will keep blowing the same pressure at you when you inhale and when you exhale. One pressure for both inhaling and exhaling. If the autopap senses you need 10, it will blow 10 for inhale AND exhale. If it senses you need 20, it will blow the SAME pressure... 20 for inhale AND exhale.

A basic bilevel machine will keep blowing the same higher pressure at you (IPAP) when you inhale, but will always blow a LOWER pressure at you (EPAP) when you exhale. TWO DIFFERENT pressures...one for inhaling and a lower one for exhaling.

In an autopap, if you had the range set at, say, 8 - 16, and at some point during the night the autopap had moved up to 16 to treat you, you are going to be inhaling at 16 and also EXHALING against 16.

The bilevel machine set at 8 EPAP / 16 IPAP would always give you 16 pressure for inhaling and would ALWAYS give you a lower pressure of 8 for exhaling.

Autopap: you could be trying to breathe out against 9 or 10...14, or 15, or 16...whatever it had had to go up to during the night.

Bi-level: you would never have to breathe out against any more than the EPAP pressure of 8, all night long.

Which would you rather try to exhale against? Which do you think would feel easier to breathe out against? Breathing out against 16 at some points during the night, or breathing out against 8 all night? Certainly many people can get used to whatever the pressure and not have trouble breathing out against the higher pressures. But some can't get used to it, or have difficulty that wakes them up.

Relief from pressure when exhaling can make a tremendous difference to someone who has difficulty or discomfort with breathing out against certain pressures. Can make the difference between being able to do "cpap" treatment at all, or having to quit.

There are many ways to get exhalation relief. Some of those ways are "features" (C-Flex, EPR) in some straight CPAP machines, or C-Flex or A-Flex in some Autopaps. Or -- going to a different type of machine entirely...a bilevel machine.

Even within the bi-level category there can be different "features" for handling the pressure relief during exhalation. Like Bi-flex to smooth out the transition between inhale/exhale in the Respironics BiPAP bilevel machine. Bi-flex being a feature that softens even more the beginning of the already lower EPAP exhale pressure setting, yet letting the necessary "full" EPAP pressure be in place for the remainder of the exhalation and for any pause at the end of the exhalation.

khvn wrote:My LO would take care of my CSA just like your EPAP does yours. My HI would take care of the rest just like your IPAP does for you...

Nope. Not "just like."

khvn wrote:But here's the rub, you probably paid much more for the bilevel than I for my APAP. This begs the question: should we part with our hard-earned money just because the establishment tells us to fork them over for an expensive piece of machine that we may not need after all?

I haven't seen any of the medical establishment urging people to fork over money for a more expensive type of machine they might not need after all. If anything, the medical establishment (driven by concerns about what the insurance establishment will pay for) usually DOESN'T prescribe more than a bare bones straight cpap machine. Even if a doctor knows or suspects that a different type of machine or a "comfort" feature of some kind might lead to better compliance and/or better treatment.

Or to even being able to "do" the treatment at all.

Heck, when it comes down to being able to "do" any kind of xpap treatment, it really comes down to the mask. An uncomfortable mask is the single one thing that probably causes more dropouts than any machine or pressure setting, or less than optimum "treatment results" does. But that's a whole different kind of discussion.

RG, I really don't think khvn is capable of understanding because he is fixated/programmed on some "establishment" out to get everyone with bi-levels. That is why he reads right through everyone's posts picking and choosing words and then making nonsense out of them.

I guess there are just some people who believe in a flat earth and/or some who will never believe in evolution ... so for some, ignorance is true bliss

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