CPAP vs APAP vs BiPAP (poll)

robysue wrote: . . . the S9 AutoSet is NOT a true bi-level machine . . .

-SWS wrote:. . . EPR IS true BiLevel, robysue . . .

For the record, I think you are both right.

EPR delivers two pressures, one for inhale and one for exhale, so in that sense, it IS bilevel. True.

But the way the transition between those two pressures feels can differ significantly. For some patients, anyway, a bilevel machine can feel very different from a CPAP/APAP using EPR.

As one respected user explained in her particular case in February 2008:

. . . 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. . . .--viewtopic.php?p=245729#p245729

Of course, EPR with Easy Breathe has likely come a long way since then. So that might not be so much the case today. I don't know.

I was prescribed bilevel and use it today. But I hope to make my next machine an APAP with EPR by getting my primary-care doc to write me a CPAP Rx. I think suspending the pressure drop for events is a way-cool idea.

jnk wrote:

robysue wrote: . . . the S9 AutoSet is NOT a true bi-level machine . . .

-SWS wrote:. . . EPR IS true BiLevel, robysue . . .

For the record, I think you are both right.

EPR delivers two pressures, one for inhale and one for exhale, so in that sense, it IS bilevel. True.

But the way the transition between those two pressures feels can differ significantly. For some patients, anyway, a bilevel machine can feel very different from a CPAP/APAP using EPR.

I'll have to politely disagree here, Jeff... *[footnote] So far the "EPR" versus "BiLevel" comparisons discussed have been exclusively comparing Resmed "EPR" against non-Resmed "BiLevel". Then the implied assumption is that last non-Resmed BiLevel is some kind of universal BiLevel for comparison. The various BiLevel brands feel different when comparing brand A against brand B.

Resmed first developed and employed that same BiLevel switching on their Adapt SV---which is a BiLevel implementation. Then Resmed took THAT BiLevel functionality and directly ported it over to their S8 generation machines. So EPR transitions as contemporary Resmed BiLevel machines transition. But EPR does NOT "feel" the same as all the non-Resmed BiLevel examples that have been compared... Rather, I think Resmed BiLevel/EPR feels different than non-Resmed BiLevel. And Resmed BiLEvel/EPR certainly feels different than Flex features as well.

But Resmed VPAPs DO at least allow for more BiLevel adjustments or "fine tuning"---and THOSE can conceivably make an EPR-intolerant patient more comfortable with Resmed's VPAP tailoring or "fine tuning" IMO. So there we have EPR as stripped-down BiLevel versus highly customizable BiLevel.

P.S. As a side note, I can't get Respironics' BiLevel (with or without Flex) to cycle comfortably for me. But the fact that EPR triggers very comfortably tells me to stick with Resmed BiLevel's if I ever need one... More importantly, I know better than to breathe into a tube and generalize either patient-response characteristics or even design characteristics based on my own potentially unique/anomalous breathing presentation. I'd recommend Respironics BiLevel, or the other brands, despite my own incompatible and unique breathing.


* [note: please see my retraction five posts below]

-SWS wrote: . . . I'll have to politely disagree here, Jeff...

Cool! That means I'm learning something, then.

-SWS wrote: . . . EPR transitions as contemporary Resmed BiLevel machines transition. . . .

That is good to know. Thanks.

I couldn't get the Respironics autobilevel to follow my breathing very well, either.

Very sneaky (but smart) of that ResMed to sell bilevels as CPAPs!

jnk wrote: Very sneaky (but smart) of that ResMed to sell bilevels as CPAPs!

<snicker>

Muse-Inc wrote:To few posting here now know about he "fast" vs "medium" ResMed settings and how it affects the 'feel' of the delivered pressure.

Hmmm... I personally found Resmed's EPR@ 3cm to be so comfortable, that I didn't even think of trying "fast" vs "med" mode---which is available in CPAP mode but not my usual APAP mode. But here's a comparison graph:



We can see above that "med" (solid blue graph) looks like EPR's usual, rounded curve and that "fast" (dotted blue graph) looks like the previous-generation BiLevel waveform. Additionally, "fast" has a much quicker slope or rise to peak pressure. So I think of "fast" as being a more traditional BiLevel transition, but also much quicker to reach maximum inhale pressure. That fast rise might have been even less comfortable for Robysue...

Robysue, are you certain your "tickling" wasn't FOT commencing at the 4-second mark for longer-than-usual expiratory pauses? What can we estimate the proportional magnitude of the 3cm's rise to be right where I drew that green line? I'm kinda eyeballing it at around half a cm, while FOT is 1cm peak-to-peak.

-SWS wrote:
Robysue, are you certain your "tickling" wasn't FOT commencing at the 4-second mark for longer-than-usual expiratory pauses? What can we estimate the proportional magnitude of the 3cm's rise to be right where I drew that green line? I'm kinda eyeballing it at around half a cm, while FOT is 1cm peak-to-peak.

Unless it was tickling on EVERY single exhale? I don't take that long to exhale on EVERY single breath. And when the tickles happen, they happen on EVERY single breath.

Now I'll admit, when fully conscious I could easily detect those FOTs on really LONG exhales of the sort associated with a really deep, deep sigh or consciously relaxing deep breath that I found almost impossible to do with CPAP/APAP because it triggered getting a stomach full of air on the exhale. [It's still NOT easy with the biPAP because the inhale for such a breath is deeper than normal and that also runs the risk of my getting air in my tummy.] Same thing with the PR: If I am fully conscious and don't inhale for long enough, I can sure detect the silly puffs the PR sends my way to try to determine if the "apnea" is an OA or a CA.

Now I don't know if my normal breathing pattern is all that funny or not. But I don't think I've got a funny breathing pattern (I don't have any diagnosis of any breathing disorder OTHER than OAS), so it may simply be that I am more aware of the "flat" portion of the wave form of my breath pattern and think of it as belonging to the exhale rather than the inhale. I also know that sometimes I'll exhale for a bit, stop for the merest fraction of a second, and then start exhaling again if my nose is itchy or feels stuffy. And during that moment between the two parts of the exhale, the S9 always seemed to start increasing the pressure. Maybe I should dig up some old wave form data from the S9 and post it and y'all can tell me if it looks funny to you.

To further muddy the waters, here's the graphic of Bi-Flex off the Resprionics website. Now, I can't find a picture of the Rise Time wave form, but as I recall, it was much more a regular square wave: There was no dip below the EPAP at all---just a vertical line dropping the pressure immediately down to EPAP at the start of the exhale, and instead of a vertical rise at the start of the inhale, there was a small lag in time up to full IPAP pressure, but the shape was still more or less a vertical line. (The drop back down to EPAP was a vertical line, unlike the form shown for the highest Bi-Flex settings.)

Now compare the Bi-Flex picture and what I described for the Bi-Flex = OFF (NO dip below the EPAP line at ALL---i.e. A FLAT pressure line during the ENTIRE exhale phase of the breath) to the EPR Easy breath pictures previously posted:


In the first, there's hardly ANY flat transition in the patient's airflow---i.e. a spot where the patient is not actively breathing in nor out at a significant rate: That is NOT true of my breath pattern---I do typically have a well defined pause after most exhales where there is little or no air moving before starting the next inhale, and psychologically I think of this as being part of the "exhale" regardless of how the machine attached to my nose decides to interpret the flow data. And in the later, it's quite clear (due to -SWS's clever added drawings) that the pressure DOES start a very subtle increase during the flat part of the breath when there's very little air moving in or out of the patient's nose---the part of the breath that I identify as being part of my exhale and that small, but subtle increase in pressure does make me feel like the S9 is trying to rush me to breathe in.

NOTE 1: I felt just as rushed (probably MORE rushed actually) when I did a 30 minute experiment with Bi-Flex the first night I had the PR S1 BiPAP. Given these graphs is it any wonder that I so quickly discovered that I needed to turn Bi-Flex OFF?

NOTE 2: If bi-level means TWO distinct pressure levels that are maintained during each and every breath, then I'm not sure EPR's Easy Breath wave form really is bi-livel. I'm not saying that it is not comfortable. I'm sure it's quite comfortable for many, if not most people. But a constant pressure is maintained in neither the majority of time during the inhale or exhale portion of the breath. The pressure is repeatedly peaking at what is approximating an IPAP pressure and it's momentarily bottoming out during part of the exhale at what is approximating an EPAP. But that's not the same as having a constant EPAP throughout the entire exhalation part of the breath.

NOTE 3: Note that in the bi-level the pressure drops immediately to EPAP when the exhale starts. With EPR, the pressure starts to drop (even before the exhale starts), but does NOT reach the minimum exhale relief pressure until well after most of the exhalation effort has been done (as measured by the lowest part of the patient's flow wave). That is another critical difference between real bi-level and the EPR algorithm. And in my opinion, in this sense, EPR ain't the real thing.

I kept the same blue, red, and green colors for our vertical-line references---from one picture to the next:


My first comparative comment is that above is not C-Flex/A-Flex---where inhale pressure is reached BEFORE the blue line. Rather, the Above is BiPAP with BiFlex. But we can still see the blue, red, and green reference lines. Robysue is more comfortable with BiPAP's later trigger (green line) than Resmed's earlier trigger (red line).

robysue wrote:Unless it was tickling on EVERY single exhale? I don't take that long to exhale on EVERY single breath. And when the tickles happen, they happen on EVERY single breath.

I agree. If you're discussing EVERY single breath than forget about FOT as the "tickler" here.

robysue wrote:If bi-level means TWO distinct pressure levels that are maintained during each and every breath, then I'm not sure EPR's Easy Breath wave form really is bi-livel.

Well, I think we're going to confuse people with those conditional semantics. That means Resmed's new-generation VPAPs, including the VPAP auto below, are not at all BiLevel by your definition:

Above we have the waveforms for one of Resmed's newer VPAP machines. That's considered one of Resmed's BiLevel machines---as are all the VPAPs with that newer sawtooth waveform.

jnk wrote:

-SWS wrote: . . . EPR transitions as contemporary Resmed BiLevel machines transition. . . .

That is good to know. Thanks.

I'll have to retract that, Jeff. Below EPR's exhale pressure curve is smooth and parabolic. But the VPAP auto exhale pressure curve shows a distinct "V" or notch where the rise to inhale starts more abruptly. So upon comparing those two curves I have learned something as well. Thank YOU, sir!

robysue wrote:Note that in the bi-level the pressure drops immediately to EPAP when the exhale starts. With EPR, the pressure starts to drop (even before the exhale starts), but does NOT reach the minimum exhale relief pressure until well after most of the exhalation effort has been done (as measured by the lowest part of the patient's flow wave). That is another critical difference between real bi-level and the EPR algorithm. And in my opinion, in this sense, EPR ain't the real thing.

Well, I think what you just described (the beginning of EPR's exhale) probably MATCHES what Resmed does on their other VPAP machines---which people generally consider to be BiLevel. But look at my comment/oversight above regarding EPR's smooth, parabolic transition to inhale, versus VPAP's more abrupt transition.

THAT'S definitely a crucial difference between Resmed's EPR and Resmed's VPAP---and it's presumably right where you had difficulty with the pressure transition. So there's room right THERE to argue that EPR is substantially different than Resmed's other VPAP/BiLevel transitions IMO. And that difference supports Jeff's earlier anecdotal comment as well. However, Resmed's VPAP is still going to feel VERY different than Respironics' BiPAP, and I don't think there is a universal "BiLevel feel".


See the diagonal red lines below---which are where robysue probably experienced discomfort with smoother/earlier EPR transitions compared to VPAP's more abrupt/later rise in pressure:



Resmed VPAP above---with an upward pressure step that is not as transitionally smooth as EPR's, but probably commences later.



Resmed EPR above commences the transition more smoothly, but probably a little earlier--starting at the red vertical line.

And thank YOU, robysue, for a highly useful discussion!

-SWS wrote:I'll have to retract that, Jeff.

I made a post saying you were right, and then you said you disagreed with that statement, and then you retracted the disagreement, so does that mean you now agree that you were right?

Personally, I can agree with the statement that EPR is a form of bilevel. It is two different pressures for inhale and exhale, and for the entire inhale and the entire exhale.

But personally, I can still also agree with the statement that a machine with EPR is not the same as a bilevel machine, since one is EO601 and the other is EO470! A lot of people with Rx's for cpap would be in a heck of a lot of trouble if it got out the DME gave them a bilevel instead. Insurance would kill us all and then let the FDA sort us out!

I have always thought that the transitions were slower with EPR than with VPAP, but I don't know how much that matters, since gradual is often more comfortable anyway. ResMed is blurring some lines at the same time that it is smoothing them out. The shape and the timing differ from one model to the next, so it is all relative. Easy Breathe changes everything, in my opinion, with all of it.

The only thing this thread is missing is some sleepydave squiggly lines, so let's at least link to some:

http://www.apneasupport.org/post-4953.html

[edit: spelling fix]

jnk wrote:

-SWS wrote:I'll have to retract that, Jeff.

I made a post saying you were right, and then you said you disagreed with that statement, and then you retracted the disagreement, so does that mean you now agree that you were right?

This is what I was retracting---and it was in your nested quote.

. . . EPR transitions as contemporary Resmed BiLevel machines transition. . . .

I'm retracting that based on the curve areas under the diagonal red slashes in the graphs i posted just above. And interestingly...

jnk wrote: The only thing this thread is missing is some sleepydave squiggly lines, so lets at least link to some:
http://www.apneasupport.org/post-4953.html

Thanks for that. I find two things interesting about those graphs: 1) that very early version of EPR shows the "v" or notched transition, rather than the smooth parabolic transition, and 2) that same "v" or notched transition more abruptly occurs when patient inhale is on the sharp upward transition---the way that robysue supposedly finds more comfortable.


Above a "v" or notched upward pressure transition----versus the smoother, parabolic transition




Above that more sudden upward pressure transition seems to commence later--- during steep inhale


However, in the patient example above we don't see post-expiratory pauses.

And above we have a few more EPR squiggles from Resmed---obtained by the poster nicknamed "Physician". Discussion from that thread can be found here:
viewtopic.php?f=1&t=54586&p=510040#p509883

-SWS wrote:But look at my comment/oversight above regarding EPR's smooth, parabolic transition to inhale, versus VPAP's more abrupt transition.

THAT'S definitely a crucial difference between Resmed's EPR and Resmed's VPAP---and it's presumably right where you had difficulty with the pressure transition. So there's room right THERE to argue that EPR is substantially different than Resmed's other VPAP/BiLevel transitions IMO. And that difference supports Jeff's earlier anecdotal comment as well. However, Resmed's VPAP is still going to feel VERY different than Respironics' BiPAP, and I don't think there is a universal "BiLevel feel".


See the diagonal red lines below---which are where robysue probably experienced discomfort with smoother/earlier EPR transitions compared to VPAP's more abrupt/later rise in pressure:



Resmed VPAP above---with an upward pressure step that is not as transitionally smooth as EPR's, but probably commences later.



Resmed EPR above commences the transition more smoothly, but probably a little earlier--starting at the red vertical line.

Yep, those diagonal lines are indeed over the time period during the breath where I was having problem with the S9 AutoSet EPR (the parabolic EPR), which has the pressure going UP during that part of the breath stage, wheras the VPAP's wave form still has the pressure either dropping ever so slightly or remaining flat. With the VPAP, the pressure does not start to rise until the rate of inhalation is clearly greater than zero AND increasing rather steeply (-SWS's green vertical line---and rougly where the red diagonal line intersects the wave form on the right). So I'd say that even on the Resmed machines there is a subtle difference between the S9's EPR algorithm and the S8 VPAP EPR algorithm. Enough for me to tell? I don't know since I never had a chance to try out an S8 VPAP.

-SWS wrote:And thank YOU, robysue, for a highly useful discussion!

And I just want to say THANKS to both -SWS and jnk for this incredibly interesting (at least to me) and fascinating discussion about the ins and outs concerning the finer points of exhale relief versus bi-level machines in general; the differences between the Resmed EPR algorithm and the PR A-Flex, C-Flex, and Bi-Flex algorithms (and the PR BiPAP with Bi-Flex turned off); and the differences between the Resmed EPR algorithm as implemented on the S9 and the S8 VPAP.

Many, many thanks to -SWS for taking the time to add those red, blue and green lines to all the pictures of the wave forms. Those extra lines were really critical in explaining how I could feel an increase in pressure during exhale on an S9 using EPR when the algorithm says the pressure increase follows the patient's breathing pattern and does not occur before the inhale starts. And this in turn helps me understand why I had such a difficult time trying to adjust to an excellent machine, and why in the end I simply could not do it. And at the same time why I'm doing just fine on an equally excellent (albeit much more expensive) machine that has a different algorithm---even though the conventional wisdom seems to say that at my pressure settings of IPAP/EPAP of 8/6 I shouldn't be able to tell any significant difference in how a PR System One BiPAP (with Bi-Flex OFF) or an S9 AutoSet or Elite set at 8cm with EPR = 2 feel.

-SWS and jnk: It's been a lot of fun sorting this stuff out with you!

WOW! I never thought a simple poll would spur so much discussion and provide so much great information. I did not realize there was as many variations as I now see, and I am sure as new units come out there will be more options and more differences.

I have learned a great deal from all the discussions and it is helping me much better understand things as I am now using a machine and need to understand what the impacts are of some of the options. The clarification on ResMed's EPR in particular have been very informative.

tschultz wrote:WOW! I never thought a simple poll would spur so much discussion and provide so much great information.

I'm glad, too, that you started the poll, tschultz.

-SWS knows this stuff, inside/out. jnk does, too.

As you said, great info.

Why would your doctor get you a APAP capable machine and leave it in CPAP mode?

Thanks