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Banned wrote:

-SWS wrote: The Resmed sports car attempts to tell the passenger when to breath more quickly or more slowly while the Respironics machine does not. They both attempt to adaptively adjust the IPAP level on a breath-by-breath basis, as-needed.

SWS-
I may have taken this statement out of context but the ResMed sports car doesn't tell the passenger when to breath more quickly or slowly. In my experience it adapts automatically to my breath flow rate so, as the driver, I tell it when to accelerate or slow down.

Banned, that Resmed algorithm does, indeed, adjust F along with PS:

PAV algorithm inside Resmed ASV wrote: Adaptive Support Ventilation
• If no spontaneous effort to breathe, machine delivers required minute ventilation (VE) as pressure control, comprised of pressure support (PS) and rate (f).
• If patient starts to breathe spontaneously, machine reduces f and lowers PS to keep VE above set minimum.
• If spontaneous tidal volume (VT) is > target and f <target, PS is reduced and f is increased.
• If VT > target and f > target, PS is lowered and f is reduced.
• If VT < target and f > target, PS is increased and f is lowered.
• If both VT and f are < target, machine increases f and PS

The f-adjustment target/weighting factor is probability-based from known flow-pattern variants of typical central dysregulation. If f-adjustment cannot yield the desired results, then an off-the-shelf back-up rate of 15 is progressively employed. When the Adapt SV does determine a need to adjust f, then it will do so by pinning up those discrete flow-based targets in an either advanced or delayed manner of delivery sequence.

Amazingly patients claim that they don't feel that f adjustment (with f being the machine's own target-based pressure-modulation frequency). On the contrary they report the exact opposite sensation (when the ASV does happen to work for them that is): The smoothest xPAP breathing they have ever felt. I still suspect that stretch-receptor patterning factors into efficacy for at least some of these patients as much as CO2 is guaranteed to factor in for very many cases. Pure wild-man speculation on my part.

Banned wrote: As I have learned on this forum, the only application where a patient may do better without an VPAP Adapt SV is shallow-breathing problems, and even that would be suspect if you did as SAG eluded too earlier, spin the dial up until the machine becomes a straight VPAP.

I think the VPAP Adapt SV is a very bad match up for typical obstructive apnea patients, Banned, and so does Resmed. But I can't blame you one bit about being Gung-Ho about this machine if it accounted for such a dramatic improvement in your sleep. IMHO it can be very tempting but altogether misleading to universalize or generalize our own (very often biologically unique) sleep therapy results. One size does not fit all when it comes to xPAP machines---including the amazing VPAP Adapt SV machine as well as the near-equivalent Respironics SV machine (which has it's own somewhat "subtly unique" set of therapy advantages).

Banned wrote:dsm-
Thank you fort the BiPAP AutoSV titration link. I've always been curious as to how home titration's work.

That link, which I had put in a previous post, is a guide for sleep labs about how to do a titration with that machine during a sleep study IN a sleep lab, with the user hooked up to PSG equipment. I don't think that was a "how-to" for a home study, or for trying to adjust that machine at home.

Banned wrote:

-SWS wrote: The Resmed sports car attempts to tell the passenger when to breath more quickly or more slowly while the Respironics machine does not. They both attempt to adaptively adjust the IPAP level on a breath-by-breath basis, as-needed.

SWS-
I may have taken this statement out of context but the ResMed sports car doesn't tell the passenger when to breath more quickly or slowly.

Oh, I think it probably does -- for the people it was really designed to treat -- those with predominately central apneas and/or Cheyne-Stokes respiration during the phase when respiration gets shallower and slower....to the point of ceasing temporarily with a central apnea.

Banned wrote:As I have learned on this forum, the only application where a patient may do better without an VPAP Adapt SV is shallow-breathing problems

I dunno. We all have to be careful about what we think we've learned... anywhere.

I guess I'm not sure what you mean by "shallow-breathing problems." The waning phase of Cheyne-Stokes respiration is often described in medical literature as a period of increasingly shallow breaths. The Adapt SV is certainly intended for patients with that kind of periodic "shallow-breathing problem."

SWS,
Re the deadspace - I was sure you merely used the wrong label - I do it all the time when try to explain how this stuff all works

Banned,
As a useful bit of info re quietness, Friends of mine who usually use the good ole Respironics TANK model Apap, now have a Bipap AutoSV to compare & both commented how quiet that machine is too.

Also RG, they used the Respironics link to the lab titration to help set up their epap / MinIpap / MaxIpap (but mostly some initial settings I gave them), and as best as I can tell - they have it right. But, one suggestion I gave them was to set the rate to 'auto' - that is the only real gotcha in the Bipap AutoSv settings that some people might get wrong if they set a rate number without knowing why.

DSM

PS RG, thanks - it was one of your links that led me to the Resp site that had that PDF - I have managed to gather so much good info from your links.

It is interesting that both Resmed and Respironics have left these docs open to public access (compared to not doing so previously).


DSM

Hey SWS and RG,

I agree with both of you. The Adapt SV certainly does adjust for PS and F during an SV episode. The issue is while you do feel the increased PS, the adjustment to F feels allot more subtle. When I think about it, both PS and F are happening very fast, so thanks for the insight. I mis-took SWS original comment to be played out during none SV episodes when 'normal' breathing paces the machine, and not the other way around.

I have no issues if a ResMed doctor says the Adapt SV is not good for OSA or Shallow Breathing, or anything else. The real crime is that IMO they should be saying that this machine may actually work for other medical venues beyond just sleep apnea. Which would probably be my case.

Here's some Adapt SV trivia.. MAX PS is really not MAX PS. Real Max PS is 5 cmH2O higher than stated. The machine can always go further than MAX PS.

Banned

RG - Thanks for providing the BiPAP Auto SV titration link. I'm actually going to try and resist spinning the dials on this home titration venture. I'll let you know it the IPAP pressure goes crazy (which never happens on the Adapt SV)

[quote="Banned"]Hey SWS and RG,

I agree with both of you. The Adapt SV certainly does adjust for PS and F during an SV episode. The issue is while you do feel the increased PS, the adjustment to F feels allot more subtle. When I think about it, both PS and F are happening very fast, so thanks for the insight. I mis-took SWS original comment to be played out during none SV episodes when 'normal' breathing paces the machine, and not the other way around.

I have no issues if a ResMed doctor says the Adapt SV is not good for OSA or Shallow Breathing, or anything else. The real crime is that IMO they should be saying that this machine may actually work for other medical venues beyond just sleep apnea. Which would probably be my case.

Here's some Adapt SV trivia.. MAX PS is really not MAX PS. Real Max PS is 5 cmH2O higher than stated. The machine can always go further than MAX PS.

Banned

RG - Thanks for providing the BiPAP Auto SV titration link. I'm actually going to try and resist spinning the dials on this home titration venture. I'll let you know it the IPAP pressure goes crazy (which never happens on the Adapt SV)

So anyway, the big burning question is how does the Resmed ASV designer determine circuit impedance with the above equation while not using a proximal sensor line?

Recall when I applied Ohm's Law (pressure/flow/resistance) relationships to show that total circuit resistance can be thought of as a dynamic restive component plus a fixed resistive component? That resistance was derived from the above equation using highly practical fluid dynamics approximations.

I ended up deriving a forward-flow "sum total" resistance as: "(K1 x Flow) plus K2".

I also derived a reverse-flow "sum total" resistance as: "negative"(K1 x Flow) plus K2"

[on edit: the above "(K1 x Flow) plus K2" is proposed at the top of page 9 as a basis for multiple instantaneous-point (recognition-based) circuit-identification; statement about pulse-reflected transient-domain kinetic dispersion effects removed as well because they seemed to have caused confusion for the steady-state oriented readers)

If we can measure flow in both forward and very-brief (turbulent) reverse flow scenarios, then we have enough information to algorithmically map both K1 and K2 values. [on edit: these are the timeline-based unique kinetic-dispersion patterns before and after wave reflection that are proposed on page nine, toward fuzzy-based and table-driven circuit recognition] We can then plug those algorithmically mapped K values into the equation above. Our K values are neatly mapped and our Flow at the turbine is accurately measured.

So why not use that proximal sensor line? Because this technique was probably developed before the proximal sensor line even occurred in the R&D process. More speculation from me later regarding that original prototype (likely without proximal sensor) and the new design with proximal sensor. Guess what? If your new design has a proximal sensor, you now have the luxury to intermix both technique-sets toward: 1) fault-related general fall-back features, and 2) even a more robust Learn Circuit routine (now both corroborative and fall-back capable).

Of course, what really gnaws at me is that we could have done all this with very tiny tennis balls and one carefully-aimed miniature tennis ball cannon (our former bong, "professionally shrunken" in the remote jungles of South America thanks to both Amex and FedEx).

-SWS wrote:. Guess what? If your new design has a proximal sensor, you now have the luxury to intermix both technique-sets toward: 1) fault-related general fall-back features, and 2) even a more robust Learn Circuit routine (now both corroborative and fall-back capable).

Ok. so the new design has the proximal sensor but Learn Circuit still functions without (does not use) it?

Banned

Banned wrote:

-SWS wrote:. Guess what? If your new design has a proximal sensor, you now have the luxury to intermix both technique-sets toward: 1) fault-related general fall-back features, and 2) even a more robust Learn Circuit routine (now both corroborative and fall-back capable).

Ok. so the new design has the proximal sensor but Learn Circuit still functions without it?

Banned

Toward fault tolerance I suspect it can, Banned. Alternately both techniques might be used to corroborate each other toward ensuring some degree of increased accuracy in determining total circuit resistance.

So, if you had to choose today, a team for excellence in design to move Sleep Apnea technology forward, would you pick the ResMed team or the Respironics team?

Banned

I haven't had a chance to look as closely at the Respironics design just yet. But I personally think the Resmed ASV design is absolutely brilliant.

Regardless, I think SDB medicine and technology both have a very long way to go. But that's only my unqualified lay person's opinion, Banned.

Well said. I still cringe at the thought of having had to go thru life without the advent of BiPAP/VPAP ASV technology.

Banned

I agree. I haven't been following the thread for awhile, but the Respironics unit is sure helped me.

Oddly enough, I have been on it for 7 months and all at once Medicare says I am not qualified for it. My Pulmonologist went ballistic.

Apria said some things that I found interesting. They buy regular BiPap Autos and CPAP machines by the thousands, but do not return them if they break. One of their techs apparently looks it over and either fixes it or tosses it into the "dumpster". What a waste.

Fast forward to my SV. It has started doing a weird noise when it cranks up. I have heard the sound before when a jet engine flames out or when we ingested birds. A sound that is hard to reproduce. The basic sound, when measured on a sound meter hovers around 55 DB, when the unit initially starts up it jumps an avg of 6-8DB. This is with the sound meter perched on top of my pillow, to reflect what I hear. I asked Apria to ask Respironics if this is normal or if one of the turbines is about to "shell out". That was weeks ago. I was told today they have a "loaner" for me, it will be delivered Monday. I am about 98% sure I have CCHS. I meet almost every test and it is a disease determined ... come on brain ... by exception I think it said.
It is not my heart. It is not my muscles. It is not _____ and so on. And I was born with it. We are in the process of doing the DNA test. Without respiratory support I will die. Maybe tomorrow, maybe the next night, etc.

I will sell my truck to buy one new if they say they are dropping me off it.
I got a new prescription Wed. I found a new one for $3500 or was it $3550 on the web. USA company. Hard to understand medicrap. I am on it for 7 months. They buy it at 13 months. Apria says medicrap will pay for a BiPap Auto so I asked what the difference was? Medicare pays a little over $451 a month for 13 months. I wonder what they pay for the Respironics BiPap Auto? My wife used one, I will see if I can find the EOB for it.

Also, the SV is NOT in Apria's inventory. Too expensive. Apparently they may have around 24 in the USA. But it is NOT carried on their inventory???
That is what a manager told me.

Has anyone seen the SV cheaper than the $3500 price?

All this makes me wonder if Respironics or Apria have any liability if they are talking back and forth while a customer dies from a known malfunctioning SV unit. Anyone know the answer to that one?

Dave,

Keep your eye on cpapauctions

There they can go for a lot less than $3,500 - just get them your SV prescription so they have it on file then bid when one comes up at a good low price - there won't be many people bidding against you as cpapauction require a specific prescription for an SV type machine.

I saw 3 for sale there a while back.

DSM

[quote="Banned"]So, if you had to choose today, a team for excellence in design to move Sleep Apnea technology forward, would you pick the ResMed team or the Respironics team?

Banned

-SWS wrote:

So anyway, the big burning question is how does the Resmed ASV designer determine circuit impedance with the above equation while not using a proximal sensor line?

OK, now I'm confused. The above equation is the one to use when you don't have a proximal pressure line. It is clear that Pprox does participate in Pmask and Learn Circuit, so is your discussion point how ASV would work if this was not the case?

-SWS wrote:If we can measure flow in both forward and very-brief (turbulent) reverse flow scenarios, then we have enough information to algorithmically map both K1 and K2 values.

Now why, you ask, should that K1 part of the equation (turbulent-flow related) sometimes add and other times subtract?

I don't believe either of those things occur (even if we were using K1 - K2). Negative is simply relative to baseline flow. The phenomenon is not static, it is dynamic, therefore calculated as an integral to give you a



or a

-SWS wrote:turbulent resistance, laminar resistance, the French Resistance (or was that Renaissance?)

We don't care about the resistance! We want to know what the pressure at the mask is!

Banned wrote:Ok. so the new design has the proximal sensor but Learn Circuit still functions without (does not use) it?

No, if you performed and understood the "Learn Circuit failure" experiment, you would realize that the proximal line is critical to the Learn Circuit function. It either does half of it or all of it.

SAG