Can cpap detect diff between central/obstruction? - one can!

[dsm]

Kebsa,

The machine you have ( Synchrony with AVAPS ) is a special class of machine that works differently from others. If in AVAPS mode it is delivering an assured volume & the pressure support is used to make that happen. The sleep doc dials in a tidal volume that is needed & the machine then ventilates to meet that volume for each breath.

Doug, Kebsa, I haven't had a chance to study that Wienmann info, but the above paragraph has me confused.

The Synchrony with AVAPS is a Respironics machine, as is the BIPAP AVAPS you have in your profile, Kebsa.
But in the text, Kebsa refers to a Resmed ASV. If either of you could explain the conundrum it would help me very much.

Thanks
O.

Ozij,

I based my comments on Kebsa`s profile - bipap avaps
#2 - Also, Kebsa described her condition pretty well & without doubt the AVAPS is the machine for the job so the profile entry made complete sense.

Doug

[ozij]

Which is it, Kebsa?
I thought like you, dsm, that the AVAPS would be the right machine - but at least according to text, Kebse is doing dramatically better with a Resmed VPAP ASV. (What a monotonic alphabet soup of "V" "A" "S" and "P"....!!!)

O.

[-SWS]

Am interested as to if our other investigative members (SWS where are you ) have any thoughts re the Weinmann claims.

Thanks for sharing your many SV thoughts, Doug.

Here's a marketing summary of the present Weinmann product offerings: http://www.weinmann.de/uploads/media/B_ ... N_1108.pdf. For the sake of reader clarity, I should probably point out that Weinmann uses their own proprietary term Oscillatory Pressure Signal (OPS) in lieu of this thread's more generic term Forced Oscillation Technique (FOT). My observation has always been that Weinmann does some incredibly innovative things with PAP machine design. The down side may be that their innovative designs have no competitor predicate devices (that are close enough in functionality) to make for a more expedient FDA approval process. Unfortunately high-end Weinmann machines don't seem to be available in the U.S.A. for lack of FDA approval.


I think industry-wide Forced Oscillation Technique (FOT), as a differentiation technology, has been interesting to watch from our distant perspective as PAP machine consumers. One interesting point of consideration is that FOT is a slightly-invasive detection technique. Resmed cites a concern in their own patent description that forced oscillation as a detection method has the potential to disturb sleep. With the exception of one highly-specialized AutoSet model that is not readily available, Resmed has apparently elected to avoid the technique altogether.

At this point in wondering just how technically-feasible FOT might be as a central-versus-obstructive detection method, I would personally consider the possibility of non-technical factors such as competitor marketing, business-oriented political strategy, etc. For all I know FOT, as a minimally-invasive detection technique might be: 1) a superior detection technique with no downside, 2) problematic regarding sleep disturbances in a significant percentage of patients, or perhaps even 3) a detection method that rightly enjoys stature somewhere in the middle of those two extremes.


Weinmann used to devote considerably more marketing text highlighting their oscillation detection method as unique and highly effective. But that was a few years ago when they were advertising their original SOMNOsmart APAP machine. I believe at the time they only offered one APAP design. However, I have noticed that Weinmann now devotes very little marketing text to underscoring that same oscillation detection method employed in their SOMNOsmart 2. For all I know, that marketing decision may have been forced by Weinmann's competitors having effectively played down FOT as a viable detection method. IMO there may be genuine epidemiological merit to those claims, or the claims may simply be strategical competitor claims with little or no technical merit. Such are the realities of an inherently competitive global free market I suppose.

The Weinmann product sheet I have linked above happens to include a new APAP design that does not employ FOT (also called "OPS" by Weinmann). However, like the SOMNOsmart 2, that new APAP model takes a multivariate algorithmic approach toward differentiating central-versus-obstructive sleep events. Both APAP models employ a multivariate approach because they actually rely on an entire variety of flow signal components and variables to differentiate central events from obstructive events. However, the new SOMNObalance e APAP model does not use FOT in its multivariate approach toward SDB differentiation. Rather it relies on Obstructive Pressure Peak (OPP) technology instead. Unlike FOT, OPP is a non-invasive detection method.




Unfortunately the Weinmann marketing literature doesn't tell us whether the SOMNOvent CR happens to rely on OPP, FOT ("OPS"), neither differentiation method, or both. But the bottom-line question will always be: "How much efficacy will any machine design lend an entire patient population?" Unfortunately that most crucial question can never be answered by analyzing marketing sheets and patent descriptions alone. Regardless, the SOMNOvent CR seems to be the most feature-rich of all current SV type designs. Hope it's a winner!

[gobears]

Great thread. Now I fully understand how servo ventilation and other more advanced technologies can help with non-standard OSA issues (flow limitations, complex, etc...). Thanks so much!

I guess if you make a trip to Europe, you could buy a machine there and bring it home? I might just do that next time I have a business trip in Europe. I suppose you would need to know a medical professional. Could be well worth it if it can bump the RDI close to zero.

I think its kind of fun how folks on this board pursue the ultimate AHI=0 goal. For the sufferers of A, H & RERA's, our goal is RDI=0! I guess these more advanced technologies, once they go mainstream and become lower in cost, will enable that goal.

[-SWS]

Now I fully understand how servo ventilation and other more advanced technologies can help with non-standard OSA issues (flow limitations, complex, etc...).

Bear in mind that employing SV technology to automatically address UARS flow limitations is contrary to what the Resmed and Respironics SV designs claim. They don't algorithmically "round out" the patient's inspiratory or expiratory curves. Rather, those SV algorithms repeatedly average patient flows and strive to hit those targets. So those algorithmic methods can essentially ignore slight sleep-intrusive flow limitations that are virtually constant---such as FL-persistent UARS. Resmed Adapt SV delivers a smooth machine-side pressure curve, which is not at all tantamount to achieving a smooth (and flow-limitation free) patient flow curve.

Rather, it was Dr. Krakow's manual BiLevel titration method (of deliberately rounding out inspiratory and expiratory patient flow curves) that has been proposed on this board as a potentially effective BiLevel technique for countering UARS. The above two SV algorithms don't do that. Because they are flow-average-oriented designs (employing no FL wave-shape detection), both manufacturers ask that the obstructive component be manually titrated---leaving automated SV delivery for a more data-coarse recent-average flow-targeting. To the best of my knowledge, dsm is the only one who has suggested employing SV technology to address UARS (different thread). I think that's fine as an opinion. However, I don't see that kind of UARS targeting mentioned anywhere in industry-wide marketing literature, medical studies, or patent descriptions regarding SV technology. Doug may have to step in and correct me if that UARS/SV claim is substantiated anywhere in the industry---because I get things wrong all the time.

So far I see nothing in the SOMNOvent CR literature to imply that inspiratory and expiratory curves are very neatly rounded out to effectively address FL-persistent or constant UARS. The SOMNOvent CR may automatically address a UARS component as well or poorly as traditional OSA-targeted APAP machines address UARS. The SOMNOevent CR may actually be much better at automatically addressing impedance variations rather than impedance constants that can be uniquely problematic regarding an effective UARS-targeted detection and pressure response routine.

With that said, the SOMNOevent CR may turn out to be darn good at addressing UARS. However I would think Weinmann would have at least mentioned UARS efficacy somewhere/anywhere in their marketing literature, pursuant profit, if the SOMNOevent CR machine just so happened to treat that condition particularly well.

[gobears]

Your points are well taken. I agree that SV technology does not directly address UARS, and also does not address getting a smooth breathing curve directly.

However, I would like to point out the following:
(1) I think the primary intended application of SV is for central and complex apneas, where the very high cost of the machine is justified by the improvement in health and reduction in risks.
(2) UARS is not yet widely accepted in the medical field yet. RERA's are not considered to be as severe as Apnea / Hypopneas.
(3) UARS is considered to be treated sufficiently by CPAP or by Dr. Krakow's Bi-Pap methodology.
(4) The advantage of SV for UARS (if there is one) migh only marginally better than Bi-pap, and hence the medical community would have a hard time justifying it for UARS given the very high cost of the machines.
(5) Interest in SV for UARS may at this point be confined to a few people with a deep interest in the technology and where it could eventually go. I would include myself in that category. With the rapid advancement of technology, I could foresee a day when the cost of additional electronics and sensors to support more advanced algorithms would be much lower.

So, SV or similar technologies for treating UARS are most likely theoretical at this point. However, I agree with DSM that SV could nevertheless be marginally helpful in minimizing RDI for some patients. In the same way that Bi-pap is more flexible than CPAP, SV just gives some additional variational ability to treat the "tougher" flow limitations. The new Weinmann product is interesting, because it goes a few more steps down the path of customizing the algorithm to the variations in breathing througout the night.

[-SWS]

I agree with DSM that SV could nevertheless be marginally helpful in minimizing RDI for some patients.

As it turns out I agree with that opinion. And when the underlying etiology of that RDI happens to be specifically addressed by what SV does well, then I think the RDI reduction can be more than minimal. One key question relates to just how applicable current SV technology happens to be across the various SDB etiologies. Another question relates to how evolving SV will be employed with other related and evolving technologies in the future (expanding the medical applicability of SV technology).

As an interesting side note, sleep science still seems to be grappling with exactly what the various underlying etiologies of RDI might entail across the SDB patient population. RERA's, for instance, are typically considered to be only a subset of all possible RDI. While some RDI is believed to be associated with sensitive peripheral blood-gas or even central chemoreceptors, RERA type RDI's are proposed by some researchers to be perhaps more related to yet other receptors that are associated with neuromuscular effort or stretch.

[dsm]

SWS & Gobears

RE UARS I believe SV (esp Vpap Adapt) can help with UARS (Flow-lims) but agree that only if the SV tracking window (3 & 4 mins & I can never remember which brand is 3 or which is 4) is sufficient to pick up the declining flow & apply PS to boost it without floating downward in pressure.

My observations really relate to me looking at my own charts from both machines, over the past year & believing that both machines appear to regularly keep my tidal volume up yet I am pretty sure I qualify (via constant nasal congestion) as a UARS (flow-lim) sufferer.

Both machine constantly keep working the PS & typically go to MAX IPAP 12+ times a night.
It may well be that other activities / events trigger the very active PS which in turn clears any UARS triggered downward Vt.

I am certainly going to stick with SV & would be interested to try the novel Weinmann approach - I am intrigued at their novel opening & closing of the ipap/epap gap as a means for regulating hyper / hypo - ventilation. My 1st thought is it would cause arousals, but, if that were true I should be getting woken each time my SV goes to 19/20 CMs but I don't believe I do.

DSM

[kebsa]

Sorry if i have quoted the wrong name for my current machine, i have tried 3 different machines over a short space of time and so many have similar names- the machine i am currently using is the Resmend Vpap adapt SV with a 2I humadiare integrated humidifier and an micro mirage mask with a ruby chin strap.

I have gone back an modified my profile, the machine i am using is not in the list of options so i have had to list it in the additional comments section. sorry for the confusion. It is definatley correct now.

[dsm]

A further response to SWS re what uses machines can be put to that may differ from what the vendors promote.

I appreciate SWS's comment that vendors are not today specifically promoting SV as a solution to UARS & I will also take time to read Dr Krakow's Bilevel set-up procedure that may be suited to UARS sufferers.

SWS also highlights the Pressure Ventilation aspect of the SV machines, in that they monitor a window of activity (3 or 4 mins dep on brand) and track a target that is 90% of the previous volume/flow & rate. The argument being that if someone spent the night suffering flow-lims then the SV algorithm may always be just insufficient to correct it.

The heart of the issue I see though is that an SV is merely a Bilevel (already there is some consensus that a Bilevel can be tuned to assist UARS sufferers) that has an added mechanism that can boost PS for IPAP. So if the UARS sufferer is breathing normally, then starts to experience flow lims, the SV will see a decline in volume/flow & should boost pressure assuming the flow-lim is not so slow happening, that it happens outside the 3/4 min tracking window.

Thus a UARS sufferer has a second mechanism (as well as the standard epap/ipap cycling) to deal with their flow-lims (UARS). The SV mechanism is specifically designed to deal with Centrals and does that by epap/ipap cycling at a back-up rate AND by monitoring volume/flow to pre-empt the central with PS as well as cycling & a central is merely a flow-lim that progressed beyond the definition of a flow-lim (vs a hypopnea vs a central - a downward volume/flow pattern).

SV machines all track & react on a breath-by-breath basis. So one case I'll argue is that an SV adds a powerful mechanism beyond a bilevel (ST or otherwise) for addressing declining volume/flow for UARS sufferers.

*************************************************************************************
Also - in regard to what vendors promote vs what their machines can do.

In the early days of Bilevels, vendors & the medical insurance industry only promoted them as specialized machines for COPD & other patients with conditions that included CSR. In 2005 I recall getting embroiled in some 'warm' debates over my argument that bilevels were a superior form of therapy to straight CPAP and to Auto CPAP. Today many regard Bilevels as the premier form of therapy for the bulk of cpap cases in that bilevels can run in any mode & in by far the majority of cases offer a better therapy experience. But in particular, once the cost dropped the medical insurance industry became more willing to accept them for more conventional cpap cases. Also it is my opinion that vendors were ready to meet supply demands & used bilevels as a way to boost sales and bilevels became therapy product du jour - I believe that was happening in late 2006 when the Respironics Bipap Auto appeared & into 2007 when Resmed responded with their Vpap Auto (Malibu).

As technology advanced the embryonic SV machines emerged (back in 2001/2) and were highly specialized machines targeting CSR. Those same machines today with little change are offered for mixed & complex Apnea. There is still some resistance to their wider use. But that is 'afaict' more a case of sticking to the known path than looking at the evidence as to what SV can do when applied in a broader scope.

So in summary if a bilevel can be considered by anyone to help with UARS, the SVs I have used & looked at certainly appear to me to offer an even better solution for predominantly UARS sufferers than any bilevel will. Perhaps with some algorithmic tweaks that extra benefit can be even further extended.
I fully expect in time to see SV machines, perhaps slightly enhanced, listed as suitable for UARS.

DSM

[dsm]

Sorry if i have quoted the wrong name for my current machine, i have tried 3 different machines over a short space of time and so many have similar names- the machine i am currently using is the Resmend Vpap adapt SV with a 2I humadiare integrated humidifier and an micro mirage mask with a ruby chin strap.

Kebsa,

Thanks for that clarification - I did see the different comments re SV & Adapt but settled on the one in your profile. However, I was happy to grab the opportunity to highlight the uniqueness of the AVAPS type machine.

DSM

[-SWS]

So in summary if a bilevel can be considered by anyone to help with UARS, the SVs I have used & looked at certainly appear to me to offer an even better solution for predominantly UARS sufferers than any bilevel will.

That's a powerful combination of machine examination followed by syllogism, Doug. And it works just fine for me by the way of message-board opinion formulation.

The medical industry at large is probably going to fuss about things like formal methodology before any of them get around to mentioning SV as a superior UARS technology. So far none of them have mentioned those two words together as far as I can tell.

[jnk]

I'll throw an opinion out there that is based on nothing more than my liking to have opinions: Bilevels are good for UARS because you tweak the PS to the point that the user's airway gets comfortable with the pressures. So I think the SV is more likely to have the opposite effect because it plays with PS to do its thing.

I don't really think I know what I'm talking about, but I felt like saying that anyway.

jeff

[dsm]

This link goes back to Dec 2007 and the 1st post is Barry Krakow's comments on Flow Limitations (UARS, RERAS).
viewtopic.php?f=1&t=26622&st=0&sk=t&sd= ... =Dr+Krakow

It is a helpful backgrounder to the issue of what type of machine today can best address Flow limitations.

Some questions

1) Can a conventional Auto do the best job with FL ?
2) Is a Bilevel better at dealing with FL ?
3) Does an SV do a better job ?

& a follow on to either question is Why ?

I see Dr Krakow covers his views on why he thinks Bilevels are better than CPAP for this.

Also at last I see an origin for the comments posted here last year as to the best gap between ipap & epap & it seems Dr Krakow is an advocate of a big gap approach. I once argued that 3/4 was enough for most people. I based that opinion on lots of experimenting with different gaps. At one time I spent 3 months using a machine set at 8/15 CMs but when I added data gathering & saw the 40+ AI data, I reduced the gap (in both directions) until AI dropped below 3.0 & that gap was 3 CMs. I then tried 3 & 4 over another 3 months & 3 always seemed to feel best.



DSM

[dsm]

So in summary if a bilevel can be considered by anyone to help with UARS, the SVs I have used & looked at certainly appear to me to offer an even better solution for predominantly UARS sufferers than any bilevel will.

That's a powerful combination of machine examination followed by syllogism, Doug. And it works just fine for me by the way of message-board opinion formulation.

The medical industry at large is probably going to fuss about things like formal methodology before any of them get around to mentioning SV as a superior UARS technology. So far none of them have mentioned those two words together as far as I can tell.

SWS
6 years ago, there would have been few to no doctors who would have said to a patient, a bilevel is the better choice for cpap therapy.
4 years ago some of the the wise heads in this forum would point out to newbies that bilevels were for serious respiratory cases like COPD.
Today we have Drs like Krakow advocating bilevel as the preferred therapy over cpap. In reading Dr Krakow & visiting his web site &
watching his clip about bilevels being the better therapy than cpap, I fully agree with him.

My point here is, that just because not many people are promoting SVs today as a better device for Flow limitations doesn't mean it isn't true.

But I do agree that outside this forum we needs lots of research & someone to do it & papers need to be written. But we can also do our own
research & come to our own conclusions in advance of the published research.

DSM