CPAPtalk.com

StillAnotherGuest wrote:
<snip>

If the concept that Dr. Krakow proposes (bilevel titration with potentially wide PS gradient, lowering EPAP and raising IPAP based on zero flow limitation tolerance) has merit, then it should absolutely become a consideration of the Titration Algorithm. This should also include "Admission Criteria" defining who may or may not benefit, for even in your own case, you are clearly a "non-qualifier".

However, eventually some objective data will need to be presented before the medical community moves en masse to adopt this new protocol, even if that objective data is subjective data ("I feel better"), as long as it's double-blind. Physiologically, I find little justification, in fact the scientific evidence seems to contradict this concept pretty much across the board. As a scientist, I would think that Dr. Krakow would welcome robust debate challenging his theory. Clearly, I cannot get through a single sentence without using at least one comma.

<snip>

SAG

SAG, I would hope we not draw all the focus too intently on one aspect of Dr K's contributions to the detriment of the others.

Put another way, "Clearly, I cannot get through a single sentence without using at least one comma", If the sentence is in English I am sure the commas are very important to most of us, but if the sentence is in Swahili, the commas will be totally lost on most of us even if the Swahili is grammatically perfect.

Cheers Doug

Just wanted to add a comment that relates back to an earlier remark by Dr Krakow that if the user stops breathing the machine will stay in that mode (ipap or epap). I think at the time Rested Gal questioned this and you offered a 'mea culpa' saying that RG was right and that Bilevel machines did drop to epap mode when the user stopped breathing.

I would add that from what I can show, you are both right but depending on the brand of machine.

I have at least 3 brands that will stay in either ipap or epap mode on *slow* cessation of airflow - mostly early or older model Bilevels but 1 recent one. I believe (as RG has pointed out) that some Respironics Bipaps will drop into epap mode on airflow cessation. Stopping breathing in suddenly on most of these machines will cause them to flip to epap but stopping breathing in *very* slowly will leave most in the current mode, but, I believe that very few people cease breathing in *very slowly* unless having a central.

Interestingly the EPR mode on the Resmed machines *will* after approx 4 seconds of breathing cessation while in epap mode, go from epap to ipap mode thus acting like it is in timed mode - this is in fact the machine disabling the EPR until the user resumes a normal breathing pattern - so the EPR (bilevel) mode actually does the reverse of dropping into epap mode. EPR is a Bilevel mode of operation.

Cheers DSM

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CPAPopedia Keywords Contained In This Post (Click For Definition): respironics, resmed

dsm wrote:Interestingly the EPR mode on the Resmed machines *will* after approx 4 seconds of breathing cessation while in epap mode, go from epap to ipap mode thus acting like it is in timed mode - this is in fact the machine disabling the EPR until the user resumes a normal breathing pattern - so the EPR (bilevel) mode actually does the reverse of dropping into epap mode. EPR is a Bilevel mode of operation.

Well that's certainly an interesting observation there, dsm! If that's the case, then EPR can be (1) airway destabilizing, considering the effect of EPAP on the airway; (2) a patient-comfort modality, relieving "Expiratory Intolerance" as proposed by Dr. Krakow; or (3) a combination of both, promoting comfort during Wake but potentially creating issues during sleep.

However, are we sure that that is, in fact, how EPR works? If so, then that could also represent a glitch in the algorithm. Has that ever been reported to ResMed?

SAG

dsm wrote:SAG, I would hope we not draw all the focus too intently on one aspect of Dr K's contributions to the detriment of the others.

Put another way, "Clearly, I cannot get through a single sentence without using at least one comma", If the sentence is in English I am sure the commas are very important to most of us, but if the sentence is in Swahili, the commas will be totally lost on most of us even if the Swahili is grammatically perfect.

Well then, I must apologize if my explanations are poor, the fault is all mine.

However, in response to your metaphor, the point remains, if you're in Kenya and somebody says, "Look out, you're going to step in kinyesi!", then there is a certain advantage to understanding Swahili.

Similarly, in discussing SDB, understanding these concepts is critical in the treatment-decision tree.

SAG

DSM,

I have a question about the Resmed S8 setting in EPR mode.
When set in this mode should IPAP/EPAP setting be similar to a regular bipap machine, correct?
Ie: My titration straight CPAP is 9 so the inhale should be 9 and the ERP settting exhale 1, 2 or 3 above the 9 correct? So the actual CPAP setting on the machine would be a 10, 11, or 12 giving you 1, 2, or 3 cm relief on exhale?
Also, The breath timing of the Resmed machine seems to sense/fit my breathing pattern much better than my new Respironics Bipap machine. What is your opinion of the Resmed EPR and their method of sensing the breath cycle vs Respironics (I notice that you use the S8 as backup only).

Thanks,
Kurt

StillAnotherGuest wrote:

dsm wrote:Interestingly the EPR mode on the Resmed machines *will* after approx 4 seconds of breathing cessation while in epap mode, go from epap to ipap mode thus acting like it is in timed mode - this is in fact the machine disabling the EPR until the user resumes a normal breathing pattern - so the EPR (bilevel) mode actually does the reverse of dropping into epap mode. EPR is a Bilevel mode of operation.

Well that's certainly an interesting observation there, dsm! If that's the case, then EPR can be (1) airway destabilizing, considering the effect of EPAP on the airway; (2) a patient-comfort modality, relieving "Expiratory Intolerance" as proposed by Dr. Krakow; or (3) a combination of both, promoting comfort during Wake but potentially creating issues during sleep.

However, are we sure that that is, in fact, how EPR works? If so, then that could also represent a glitch in the algorithm. Has that ever been reported to ResMed?

SAG

SAG,

IIRC there is a writeup on Resmed's site that explains the EPR cancellation feature.

With EPR, (Am sure you know this) the machine is set into CPAP mode with the CMS set to the users recommended titration CMS (say 13). This is in effect the ipap level.

Then (as in my preferred case) I dial the level of 1 2 or 3 CMS drop which sets the epap level. In my case when I use the machine I set it to 3 so the epap becomes 10. The nightly data doesn't present this at 13/10 but as an average of the two.

The machine then behaves like a BiLevel switching between ipap and epap (in this example 13/10 CMS). The principle seems to me to be good - a cheap Bilevel with no adjustments to worry about. The actual applied rise & fall times seem to be simlar to what I see in A-flex. But, to me the lack of rise time adjustments means the shifting between ipap to epap is 'sluggish' compared to the 'crisp' switch I can get the PB330. I know that risetime preferences are going to be as varied as the number of users so there is an aspect of 'what one gets use to'.

The aspect of this that I think cuts into your points is the clinical correctness of setting epap & ipap for any given user. EPR does it in a simplistic way, it would seem pretty certain the requirements here will vary based on the physical properties of the body, neck & throat & other health issues of the user.

I gather your specific issue relates to setting of epap for particular users whose breathing/throat circumstances can create irregular airflows and resistance.

Dr K was AFAICT talking in general terms about the setting of ipap and the point got around to the need to titrate epap separately & this was when, from what I saw, the thread fell off the rails because of crossed purposes in the discussion & the introduction of complex charts & diags that highlighted specific issues.

But I am still doing my best to follow the various points as they did get very complicated

DSM

[quote="kurtr"]DSM,

I have a question about the Resmed S8 setting in EPR mode.
When set in this mode should IPAP/EPAP setting be similar to a regular bipap machine, correct?
Ie: My titration straight CPAP is 9 so the inhale should be 9 and the ERP settting exhale 1, 2 or 3 above the 9 correct? So the actual CPAP setting on the machine would be a 10, 11, or 12 giving you 1, 2, or 3 cm relief on exhale?
Also, The breath timing of the Resmed machine seems to sense/fit my breathing pattern much better than my new Respironics Bipap machine. What is your opinion of the Resmed EPR and their method of sensing the breath cycle vs Respironics (I notice that you use the S8 as backup only).

Thanks,
Kurt

StillAnotherGuest wrote:
<snip>

However, in response to your metaphor, the point remains, if you're in Kenya and somebody says, "Look out, you're going to step in kinyesi, then there is a certain advantage to understanding Swahili.

<snip>

SAG

SAG,
But we are here in cpaptalk land with a membership of us humble plebs

DSM

dsm wrote:Just wanted to add a comment that relates back to an earlier remark by Dr Krakow that if the user stops breathing the machine will stay in that mode (ipap or epap). I think at the time Rested Gal questioned this and you offered a 'mea culpa' saying that RG was right and that Bilevel machines did drop to epap mode when the user stopped breathing.

I would add that from what I can show, you are both right but depending on the brand of machine.

That particular discussion was about:

A. Bilevel machines. Not a cpap machine with EPR (which does not operate at all like a true bilevel machine.)

B. Holding one's breath. Complete cessation, not slowing, of breathing.

dsm wrote:I believe (as RG has pointed out) that some Respironics Bipaps will drop into epap mode on airflow cessation.

Not "some"...all bilevels in spontaneous bilevel mode. And not just Respironics... any brand of bilevel in plain old spontaneous bilevel mode.

dsm wrote:Stopping breathing in suddenly on most of these machines will cause them to flip to epap

Yes. But, not just "most"...all. Remember Dr. Kracow and I were talking about spontaneous bilevel mode.

dsm wrote:but stopping breathing in *very* slowly will leave most in the current mode,

Not sure what you mean by "stopping breathing in very slowly." You're either breathing (no matter how slowly) or you're not. You can stop breathing in at all, or you can breathe in very slowly. I don't think you can do both those things at the exact same time.

If you stop breathing, the bilevel machine will switch from IPAP to EPAP.

If you breathe in very slowly (with no pause...no cessation of breathing) the bilevel machine will continue to deliver IPAP.

The only thing that could cause it to stop blowing IPAP while you are inhaling (no matter how slowlllllly you inhale..as long as you don't have even the briefest full cessation pause) is if your inhalation exceeds the amount of time the designers build into any bilevel machine for delivering IPAP.

dsm wrote:Interestingly the EPR mode on the Resmed machines *will* after approx 4 seconds of breathing cessation while in epap mode, go from epap to ipap mode

I've timed that on the resmed Elite with EPR. It's considerably longer than even approximately four seconds. If you hold your breath (breathing cessation) at any point during the exhalation...or even as a long pause after finishing an exhalation... it's more like 8 seconds, 10 seconds, or a few more before the machine suspends EPR and blows the straight pressure it's set for. That's not an "IPAP", by the way, in CPAP with EPR. It's simply "the" CPAP pressure. Only bilevel machines have separate IPAP/EPAP settings.

dsm wrote: thus acting like it is in timed mode - this is in fact the machine disabling the EPR until the user resumes a normal breathing pattern - so the EPR (bilevel) mode actually does the reverse of dropping into epap mode. EPR is a Bilevel mode of operation.

Cheers DSM

Some may call EPR a "bilevel mode of operation", but I do think it is a bit misleading (and I don't mean you are deliberately trying to mislead...I think you are quite sincere, Doug.) EPR is what it says it is... Expiratory Pressure Relief. It behaves in ways that no true bilevel machine would act. Again, remember Dr. Kracow and I were talking about plain bilevel machines in spontaneous mode:

1. bilevel machines hold the lower exhalation pressure UNTIL a person starts to inhale again. EPR doesn't.

2. bilevel machines are generally titrated so that EPAP will prevent apneas during and after exhalation. If titrated properly, the lower EPAP holds the airway open "enough" that the person can at least initiate another breath...start inhaling again. At which time the higher IPAP ideally opens the throat fully for a good inhalation.

EPR, on the other hand, drops pressure down below the titrated CPAP pressure. The very fact that the designers of EPR put a time limit on how long that lower EPR pressure can blow shows that they realized it might be subtherapeutic pressure and should be suspended if the person doesn't or can't take another breath. "Can't" as in an apnea happened and the person can't even START to inhale again. I don't think the designers put in a timer to suspend EPR to try to make the machine act like an S/T bilevel. I think they did it because IF EPR did, in fact, allow an apnea to happen because of the reduction of pressure below the prescribed CPAP pressure, one wouldn't want that subtherapeutic pressure to continue indefinitely.

Having used machines with C-Flex, A-Flex, EPR, as well as several brands and types of bilevel machines including the Respironics BiPAP Auto, I must say that exhaling with EPR doesn't even come close to the comfort of any of those others. It certainly doesn't feel like bilevel exhalation at all.

I think the resistance to breathing out one feels with EPR is because it does not drop the pressure to its full "cm drop" until well into the exhalation. EPR, even at the most drop it will give (3 cm), drops the pressure only a tiny bit when you first start to exhale. You can hear the motor winding down as the exhalation continues, until it finally does get to the full drop it's going to give.

For me, I want to feel the pressure relief at the BEGINNING of the exhalation. C-Flex, A-flex, and true bilevel EPAP, all give pressure relief at the BEGINNING of the exhalation -- where it helps the most for getting an exhalation started.

Using EPR feels better than not using any kind of pressure relief for exhaling with a resmed CPAP. But it sure doesn't feel anywhere near as comfortable or "pressure relieving" (to me) as C-Flex or A-Flex... and certainly not anything like the comfort of a bilevel machine. Even the Puritan Bennett 420E Auto feels easier to get an exhalation started with -- to me -- and that good little machine doesn't even have an exhalation relief feature. Something about the way it's fan blades work makes breathing out against it easier for me than trying to breathe out with EPR.

A-Flex comes as close to "feeling" like the comfort of a bilevel machine as anything I've tried.

Hi RG,

Some of the points you raise are covered (I think) in some of the other posts I made.

Re EPR being Bilevel. This could be just a matter of semantics. I am calling it Bilevel from the perspective that it operates at two distinct and settable pressures. Saying it isn't bilevel because EPR is programmed to drop rather than to rise does seem a semantic issue. The acid test surely is that EPR allows the machine to operate at 2 distinct settable pressures ?.

I agree that typical titration with 'traditional' bilevels usually involves using the epap as a titration baseline (but this is not law, it is a 'best practice') .

To say that dropping the epap a bit below titration, even 3 CMS, is not to or never to be done, is an arbitrary position. The epap setting is up to the respiratory specialist and the user. In my case I operate my PB330 by setting my ipap to titration & epap 3 below. That is my choice and is supported by my respiratory specialist and has worked very very well.

Re all Bilevels reverting to epap when the user stops breathing in. I will dig out the machines that I recall are staying in ipap mode. Because you are usually very spot on in matters like this I'll repeat the tests & reply with the results. On thinking about it, what you say does make sense but I am sure I found some didn't. The 1st one I will test will by the Healthdyne BiLevel.

Cheers

DSM

#2, re EPR & reverting to std CMS (what I called ipap) after 4 secs breathing out (& not breathing in) - I'll also test that again tonight I am pretty sure thats what it is but I am going from recall of tests done last year.

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CPAPopedia Keywords Contained In This Post (Click For Definition): Titration

dsm wrote:I agree that typical titration with 'traditional' bilevels usually involves using the epap as a titration baseline (but this is not law, it is a 'best practice') .

I wrote:
2. bilevel machines are generally titrated so that EPAP will prevent apneas during and after exhalation.

dsm wrote:To say that dropping the epap a bit below titration, even 3 CMS, is not to or never to be done, is an arbitrary position.

I never said it can't be or shouldn't be done. As with any titration, a bilevel titration in a sleep lab can result in less than ideal results sometimes.

dsm wrote:In my case I operate my PB330 by setting my ipap to titration & epap 3 below. That is my choice and is supported by my respiratory specialist and has worked very very well.

Here's where you lost me. "Setting my ipap to titration"... by "titration" do you mean the titration pressure from a previous CPAP titration you had? Are you talking about setting your bilevel's IPAP to the pressure you would have been prescribed if you were using a straight CPAP machine? And then setting your EPAP at 3 cms below what the straight CPAP pressure would have been?

If that's what you're talking about, it's no surprise it works well for you. The EPAP pressure which is set in a bilevel titration generally is NOT going to have to be as high as the CPAP pressure from a regular cpap titration. In a CPAP titration, the "titrated pressure" has to prevent ALL events...apneas, hypopneas, flow limitations, snores.

However in a bilevel titration, the only thing EPAP has to do is keep the throat open enough that a person can start to breathe in again. In other words, EPAP has to be just high enough to prevent full apneas.

If EPAP is set just high enough to prevent complete apneas, that's all it has to do. If the throat is not fully closed, there is no apnea. If EPAP can hold the throat partially open, a person can START to draw in the next breath. THEN the higher IPAP pressure can do its job, opening the throat fully so you can breathe in fully.

It takes less pressure (EPAP) to prevent an apnea. Or, to put it another way, it takes less pressure to keep the throat from closing completely than it does to keep the throat fully open. The higher IPAP is needed for fully opening the throat when a person starts to breathe in. By opening the throat fully when you start to breathe in, the higher IPAP pressure prevents hypopneas, flow limitations and residual snores.

So, it would be very common for someone who had had a regular CPAP titration and later began using a bilevel mchine to find that their IPAP (not their EPAP) pressure corresponded closely to what they would have been prescribed for straight cpap. An effective EPAP (remember, EPAP only has to keep the throat from closing completely) will, of course, generally be lower than a single "CPAP titration" pressure.

rested gal wrote:

dsm wrote:I agree that typical titration with 'traditional' bilevels usually involves using the epap as a titration baseline (but this is not law, it is a 'best practice') .

I wrote:
2. bilevel machines are generally titrated so that EPAP will prevent apneas during and after exhalation.

dsm wrote:To say that dropping the epap a bit below titration, even 3 CMS, is not to or never to be done, is an arbitrary position.

I never said it can't be or shouldn't be done. As with any titration, a bilevel titration in a sleep lab can result in less than ideal results sometimes.

dsm wrote:In my case I operate my PB330 by setting my ipap to titration & epap 3 below. That is my choice and is supported by my respiratory specialist and has worked very very well.

Here's where you lost me. "Setting my ipap to titration"... by "titration" do you mean the titration pressure from a previous CPAP titration you had? Are you talking about setting your bilevel's IPAP to the pressure you would have been prescribed if you were using a straight CPAP machine? And then setting your EPAP at 3 cms below what the straight CPAP pressure would have been?

If that's what you're talking about, it's no surprise it works well for you. The EPAP pressure which is set in a bilevel titration generally is NOT going to have to be as high as the CPAP pressure from a regular cpap titration. In a CPAP titration, the "titrated pressure" has to prevent ALL events...apneas, hypopneas, flow limitations, snores.

However in a bilevel titration, the only thing EPAP has to do is keep the throat open enough that a person can start to breathe in again. In other words, EPAP has to be just high enough to prevent full apneas.

If EPAP is set just high enough to prevent complete apneas, that's all it has to do. If the throat is not fully closed, there is no apnea. If EPAP can hold the throat partially open, a person can START to draw in the next breath. THEN the higher IPAP pressure can do its job, opening the throat fully so you can breathe in fully.

It takes less pressure (EPAP) to prevent an apnea. Or, to put it another way, it takes less pressure to keep the throat from closing completely than it does to keep the throat fully open. The higher IPAP is needed for fully opening the throat when a person starts to breathe in. By opening the throat fully when you start to breathe in, the higher IPAP pressure prevents hypopneas, flow limitations and residual snores.

So, it would be very common for someone who had had a regular CPAP titration and later began using a bilevel mchine to find that their IPAP (not their EPAP) pressure corresponded closely to what they would have been prescribed for straight cpap. An effective EPAP (remember, EPAP only has to keep the throat from closing completely) will, of course, generally be lower than a single "CPAP titration" pressure.

RG

Yes well put and I am in full agreement. I believe I said something similar in an earlier post re setting epap & ipap but your description is much clearer than what I said.

Also, yes did mean setting ipap to my cpap titration. In the last titration I had a year ago the clinic knew I had a bilevel but said they would do the titration using their established cpaps (made sense to me). That was for 12 but I set my ipap to 13 after some experiments.

Also, I did some looking up of info re ipap to epep transition & found this text at Resmed's website - it supports your comment re ipap in spontaneous mode Bilevels. So you made a good call on this and I accept it ...

Cheers Doug


http://www.resmed.com/en-us/clinicians/ ... clinicians

Maximum IPAP time is the maximum time a device will deliver IPAP. Most bilevel devices have a three-second, non-adjustable maximum IPAP time. ResMed bilevel devices are the only devices on the market with the IPAP MaxTM feature that allows clinicians to set the optimal maximum IPAP time for each patient during spontaneous breathing mode. Recent studies show that almost all patients on bilevel therapy experience mouth leaks, which interfere with a device's triggering sensitivity from IPAP to EPAP. Poor triggering sensitivity results in poor synchrony of the patient's spontaneous breathing pattern and the bilevel's assistance. Asynchrony causes the patient to exhale against a higher pressure, increasing work of breathing and reducing the comfort and quality of therapy. IPAP Max counteracts the effect of mouth leak and improves synchrony so that therapy remains comfortable even in the presence of mouth leaks.

dsm wrote:Dr K was AFAICT talking in general terms about the setting of ipap and the point got around to the need to titrate epap separately & this was when, from what I saw, the thread fell off the rails because of crossed purposes in the discussion & the introduction of complex charts & diags that highlighted specific issues.

I must beg to differ there, dsm, if you go back and reread the posts, it was not I who cast the first graph, and Dr. Krakow offered specific treatment approaches, including lowering EPAP if you see "bumps", and zero tolerance for flow limitations. I was then duped into thinking that posting graphs was an accepted method of offering opposing viewpoints. It became personally interesting to me when I realized that I had in my possession virtually the exact same testing criteria (PB42x flow generator, acquisition software, persistent flow limitation subject) that demonstrates entirely different results.

And in my defense, since the subject also happens to be The Official Forum NPSG Demonstration Subject, I thought it might be interesting to at least one other person.

How about a compromise? If I am going to post a graph, I'll make the Post Subject ***CAUTION - CONTAINS GRAPHS*** so people will know to skip over that post. And anything that might be perceived as "too complex" will be posted in a different color (I'll use blue) so people can bypass that as well.

SAG

dsm wrote:IIRC there is a writeup on Resmed's site that explains the EPR cancellation feature.

dsm wrote:Interestingly the EPR mode on the Resmed machines *will* after approx 4 seconds of breathing cessation while in epap mode, go from epap to ipap mode thus acting like it is in timed mode - this is in fact the machine disabling the EPR until the user resumes a normal breathing pattern - so the EPR (bilevel) mode actually does the reverse of dropping into epap mode. EPR is a Bilevel mode of operation.

OK, but that's two different things, duration of EPR and suspension of the modality (Ooops! Did it already!) I mean modality.

Darn, I'm stuck already. If I want to post a link to a graph, should I put ***CAUTION - CONTAINS GRAPHS*** in the Post Subject or put the link in blue?

SAG

StillAnotherGuest wrote:

dsm wrote:Dr K was AFAICT talking in general terms about the setting of ipap and the point got around to the need to titrate epap separately & this was when, from what I saw, the thread fell off the rails because of crossed purposes in the discussion & the introduction of complex charts & diags that highlighted specific issues.

I must beg to differ there, dsm, if you go back and reread the posts, it was not I who cast the first graph, and Dr. Krakow offered specific treatment approaches, including lowering EPAP if you see "bumps", and zero tolerance for flow limitations. I was then duped into thinking that posting graphs was an accepted method of offering opposing viewpoints. It became personally interesting to me when I realized that I had in my possession virtually the exact same testing criteria (PB42x flow generator, acquisition software, persistent flow limitation subject) that demonstrates entirely different results.

And in my defense, since the subject also happens to be The Official Forum NPSG Demonstration Subject, I thought it might be interesting to at least one other person.

How about a compromise? If I am going to post a graph, I'll make the Post Subject ***CAUTION - CONTAINS GRAPHS*** so people will know to skip over that post. And anything that might be perceived as "too complex" will be posted in a different color (I'll use blue) so people can bypass that as well.

SAG

SAG,

Thanks for that very straight forward summarization. So just to re explain, an issue arose where you consider the same data is being interpreted in quite different ways and that the data is or should be 'well known' data to professionals in the respiratory field. The data (relating to epap setting when 'bumps' show between exhale in inspiration), has important ramifications for people setting BiLevel ranges for their clients.

Allowing for where this has led, did you PM Dr K ? - (I would hope so).


Cheers DSM