No Answers Yet For Problems With ASV

[Paper_Nanny]

http://dl.dropbox.com/u/34735018/07-14% ... Report.pdf

[BrianinTN]

First off, let me just cite this, because it's the entire premise behind what I wrote and is the reason, I think, why your post and mine are somewhat arguing past each other:
http://en.wikipedia.org/wiki/Necessary_ ... _condition

As per the specifics I cited, my post was not about whether the conditions were correct or necessary. It was entirely about their sufficiency, and in all three cases, they were not.

To set the machine to cpap mode:> you set a 0 PS min (so by default there is no epap-ipap gap ) which is cpap

Not quite. There's a big difference between the Min PS setting (which is what StillAnotherGuess posted), and constraining the total and overall PS. Setting Min PS=0 doesn't do anything to ensure that the therapy the patient receives will be tantamount to CPAP. If we want to be really precise about it, let's not forget what the "C" in "CPAP" stands for. Even if you're using "CPAP" synonymously with "APAP," it still isn't quite right to equate it with Min PS=0. Just because you've told the ASV that it's allowed to keep IPAP=EPAP does not mean that it will do so. You may think of this as an issue of semantics, but to the poster who comes along here and thinks that laddy-daddy-da, they're using their ASV just like a CPAP or even APAP if they set PS min=0, it isn't.

To set the machine in cpap mode with ASV support:> (yes ! this is a valid setting )

No issue with this statement. As I recall, that is what the Respironics model two generations before the current S1 did.

you set PS min = 0 & PS max greater than zero (recomm 8-10). Thus whilst the machine runs as a cpap (epap=ipap), if it detects ASV type events the machine will use the PS max to raise pressure using ASV rules.

Both EPAP and IPAP are allowed to be raised under the settings you just suggested. But again, even if I sub in "APAP" for your use of the term "CPAP," the S1 and previous generation Respironics ASVs are allowed to modify the EPAP and IPAP differently in response to different patterns and events.

To set the machine to Bilevel mode :> you set PS min > 0 (creates an epap and an ipap) and you set PS max = PS min (removes ASV rules ).

Yes, this is what I said. Again, there are multiple conditions, none of which are sufficient by themselves.

Also, backup rate works in this setting.

Correct; with a backup rate, that's the equivalent of a BiPAP S/T device.

Whilst StillAnotherGuess doesn't always know his manners he does know his machine settings

Agree to disagree. I'll quote this gem one more time:

They probably wanted to set PS MIN = 4 and PS Max = 0, but they got it transposed.

Again, I realize how this may seem a bit like semantics, and I understand that you're trying to break things down into components of base pressure and servo-ventilation. My angle, simply, is that if you take the commonly accepted definitions of CPAP and APAP, and think about the graphs those machines would generate over the course of the night, there are more settings required to accomplish that outcome than appeared in StillAnotherGuess's posts. Which is why I said they are necessary but not sufficient conditions. If you use the guidelines that I specified, the pressures would be constrained, and you would truly be able to have the ASV act like and produce data like that of a CPAP or BiPAP.

[dsm]

<snip>

Whilst StillAnotherGuess doesn't always know his manners he does know his machine settings

Agree to disagree. I'll quote this gem one more time:

They probably wanted to set PS MIN = 4 and PS Max = 0, but they got it transposed.

Again, I realize how this may seem a bit like semantics, and I understand that you're trying to break things down into components of base pressure and servo-ventilation. My angle, simply, is that if you take the commonly accepted definitions of CPAP and APAP, and think about the graphs those machines would generate over the course of the night, there are more settings required to accomplish that outcome than appeared in StillAnotherGuess's posts. Which is why I said they are necessary but not sufficient conditions. If you use the guidelines that I specified, the pressures would be constrained, and you would truly be able to have the ASV act like and produce data like that of a CPAP or BiPAP.

BrianinTN

Firstly I said lets ignore epap MIN & MAX as they confuse the situation. I believe those potential settings still are

SAGuess was being cheeky when he posted what he said (above quote) - I don't see any 'mistake' as such, just a poke at the medical folk with the quip that 'they' wanted to set it one way but got it back the front - I didn't see SAGuess asserting anything of relevance.

Also his 3 points were correct . I agree with you though, there is a story around each one and there is a context. Change the context & the story can change. In a different context (such as yours) it is possible to quibble with the points he made. But as simple & pure statements of fact they were correct. It is a pity they had no additional comments that would have helped you with a context.

Cheers

DSM

(PS one reason I am avoiding joining in most ASV threads is it is now so clear to me that confusion rules as to the significance & relevance of the myriad of setting possible on a Respironics Bipap ASV. These days I just don't feel at all comfortable offering suggestions to anyone as to how I think they should set their ASV. That really is best left to the professionals the ASV owners are seeing even if we can see holes in what some of those professionals are doing. We can suggest they ask pointed questions of their professionals. Even NotMuffy who understands the machines very well is cautious on this aspect while dealing with unseen people here).

Cheers D

[dsm]

Can we please just go back to talking about our avatars and mask leaks and stuff? This is hard.

Hmmmm is it time for the monkey avatars to come back

Cheers

DSM

[Paper_Nanny]

SAGuess was being cheeky when he posted what he said (above quote) - I don't see any 'mistake' as such, just a poke at the medical folk with the quip that 'they' wanted to set it one way but got it back the front - I didn't see SAGuess asserting anything of relevance.

I did not realize that was a cheekiness and not wrongness. And asserting something as fundamentally wrong as setting PS min=4 and PS Max= 0 is... just wrong.

Also his 3 points were correct . I agree with you though, there is a story around each one and there is a context. Change the context & the story can change. In a different context (such as yours) it is possible to quibble with the points he made. But as simple & pure statements of fact they were correct. It is a pity they had no additional comments that would have helped you with a context.

I understand it the way BrianinTN explained, that the conditions listed by StillAnotherGuess are necessary but not sufficient for running the machine in CPAP and BiPAP mode.

As for me, I returned mine to the original BiPAP ASV mode because I wanna see what those waves look like, oh, yes, I do! I may regret it in the morning, but sometimes, that is just the way it has to be.

Deborah

[dsm]

SAGuess was being cheeky when he posted what he said (above quote) - I don't see any 'mistake' as such, just a poke at the medical folk with the quip that 'they' wanted to set it one way but got it back the front - I didn't see SAGuess asserting anything of relevance.

I did not realize that was a cheekiness and not wrongness. And asserting something as fundamentally wrong as setting PS min=4 and PS Max= 0 is... just wrong.

(DSM) What I posted was merely my impression - obviously we will all see it our own way

Also his 3 points were correct . I agree with you though, there is a story around each one and there is a context. Change the context & the story can change. In a different context (such as yours) it is possible to quibble with the points he made. But as simple & pure statements of fact they were correct. It is a pity they had no additional comments that would have helped you with a context.

I understand it the way BrianinTN explained, that the conditions listed by StillAnotherGuess are necessary but not sufficient for running the machine in CPAP and BiPAP mode.

(DSM) if BrianinTN's post worked for you that is good (your thread )

As for me, I returned mine to the original BiPAP ASV mode because I wanna see what those waves look like, oh, yes, I do! I may regret it in the morning, but sometimes, that is just the way it has to be.

Deborah

[Mr Bill]

PS Min and PS Max are two different animals..
Keep repeating the mantra until it sinks in:
CPAP therapy: PS Min = 0
Bilevel therapy: PS Min > 0
ASV therapy: PS Max > 0

Wrong, wrong, wrong and also, wrong. (Yes, that's 4 wrongs -- one for the initially silly statement, and three for the next three necessary but not by-themselves-sufficient conditions.)

First off, let's clarify a definition, shall we? In Respironics language, PS (pressure support) is defined as the difference between IPAP and EPAP. If you set Min PS > 0, you are enforcing the constraint that some bilevel support will be employed -- i.e., IPAP will always be larger than EPAP. Max PS specifies the maximum bilevel support the ASV will attempt. I have seen the term "pressure support" used in various literature in different ways, but with respect to a Respironics device, this is what it means.

This is the second time in this thread that you have insisted (incorrectly) that "PS Max > 0" is "ASV therapy." Putting aside the obvious issue that nearly all ASV users employ a backup rate, the condition as specified is still not sufficient. Let's start be creating a random variable x, and specifying that PS Min = PS Max = x, where x > 0. The implications of that, ignoring ramping, are as follows:

• The user's ASV will run in the equivalent of automatic bilevel mode
• The difference between IPAP and EPAP will always be static (equal to x), and EPAP and IPAP will increase or decrease concomitantly and by the same absolute values
• The maximum possible IPAP is constrained by the lesser of either Max EPAP + x or Max Pressure
• The maximum possible EPAP is constrained by the lesser of Max Pressure - x or Max EPAP
• The minimum possible IPAP would be min EPAP + x

To put these equations into an example, let's set x to 4 and specify the remaining variables as follows, preserving that condition: Min EPAP = 8, Min PS = 4, Max PS = 4, Max EPAP=15, and Max Pressure = 30. Under these parameters, possible pressures (when not ramping) would be 12/8, 13/9, 14/10,..., 19/15. IPAP will always equal EPAP + 4. Note how constraining Max PS to 4 means that there would be no functional difference at all between setting Max Pressure = 19 and setting Max Pressure = 30.

Similarly, PS Min > 0 is not a sufficient condition for straight traditional bilevel therapy either. If PS Min = x > 0 and PS Max > PS Min, IPAP will again be allowed to vary, but it will always exceed EPAP by an amount greater than or equal to x. Let's pretend this time that Min EPAP = 8, Min PS = 4, Max PS = 15, and Max Pressure = 30. (Note the only difference from my preceding example is that I have specified Max PS = 15). Some possible pressures (again not while ramping) would include 12/8, 13/8, 14/8, 13/9, 14/9, 14/10, 15/10, etc. The maximum possible pressure combination would be 15/30, and the minimum IPAP given that maximum EPAP would be 19/15. Bilevel always? Yes. Static difference between IPAP and EPAP, as most BiPAP and Auto-BiPAP users see? Nope.

And while I'm at it, PS Min = 0 is also not a sufficient condition for CPAP mode. A great many of us run our ASVs with PS Min = 0, including myself when using a FFM. All that does is permit the ASV to try IPAP = EPAP. It does not prohibit IPAP from exceeding EPAP. IPAP and for that matter EPAP can both bounce around, constrained of course by Max Pressure, Max PS, and Max EPAP. Setting PS Min to 0 by itself prohibits neither bilevel nor ASV therapy.

I imagine the RTs screwed up when they set-up your new machine. They probably wanted to set PS MIN = 4 and PS Max = 0, but they got it transposed.

WTF? I'm not sure where you got the idea that Max PS can be less than Min PS, but once again, wrong. In addition to failing a basic common sense check, I tried to see if my ASV would let me do that. It doesn't. Score a victory for the little man and common sense.

Hi BrianinTN

I realise the issue of settings on the Resp ASVs can get very confusing - just wanted to add some further interpretation ...

SAGuess posted
1. CPAP therapy: PS Min = 0
2. Bilevel therapy: PS Min > 0
3. ASV therapy: PS Max > 0

1 is true
2 is true
3 is true (with qualifications)

On an Respironics ASV (lets ignore epap min & max as they merely add to the confusion)

To set the machine to cpap mode:> you set a 0 PS min (so by default there is no epap-ipap gap ) which is cpap

To set the machine in cpap mode with ASV support:> (yes ! this is a valid setting ) you set PS min = 0 & PS max greater than zero (recomm 8-10). Thus whilst the machine runs as a cpap (epap=ipap), if it detects ASV type events the machine will use the PS max to raise pressure using ASV rules.

To set the machine to Bilevel mode :> you set PS min > 0 (creates an epap and an ipap) and you set PS max = PS min (removes ASV rules ). Also, backup rate works in this setting.

Whilst StillAnotherGuess doesn't always know his manners he does know his machine settings

DSM

What DSM says and what StillAnotherGuess said made sense to me. Sorry BrianInTN, I had trouble following your argument. In support of what I posted and what SAGuess posted and DSM clarified, just look at the wave forms. It seems obvious that pressure intervention was taking place.

[BrianinTN]

Sorry BrianInTN, I had trouble following your argument. In support of what I posted and what SAGuess posted and DSM clarified, just look at the wave forms. It seems obvious that pressure intervention was taking place.

Which part are you not able to follow or understand? Paper_Nanny obviously got it, so there must be something I'm not explaining well enough.

A CPAP device will enforce a single flat pressure throughout the entire night. Leaving PS Min = 0 in and of itself will not force an ASV to keep a single flat pressure.

A BiPAP device will enforce a single exhalation pressure (EPAP) and a single inhalation pressure (IPAP) throughout the entire night. Simply setting PS Min > 0 does nothing to keep those two constant throughout the night.

I don't know how I can be any more clear about it. You are on exactly the right track about looking at the graphs, though. They demonstrate precisely what I'm saying.

Again, conditions must be both necessary and sufficient. If I tell you that if you want to create the color purple, you will need red, is what I've said correct? Yes. Necessary? Yes. Sufficient? No way.

What DSM says and what StillAnotherGuess said made sense to me.

This reminds me of an old favorite quote from a few months back:

Banned...Your opinions always make sense to me.

I won't blame you for not knowing any better. But that's one very unsettling quote IMHO.

[Mr Bill]

What you just said made sense. Its late, I just got back from the Harry Potter movie and your equations made my eyes glaze over. I did not mean to be critical and it was enough for me that DSM took the time to understand what you said and say that it amounted to the same thing. For me, especially when I'm tired, words tend to be more immediate and intuitive. Equations engage a different part of the mind and while I love them, I need concentration and thought and spreadsheets to deal with them.
Anyway, we all seem to be in agreement, which is a happy ending.

[dsm]

What you just said made sense. Its late, I just got back from the Harry Potter movie and your equations made my eyes glaze over. I did not mean to be critical and it was enough for me that DSM took the time to understand what you said and say that it amounted to the same thing. For me, especially when I'm tired, words tend to be more immediate and intuitive. Equations engage a different part of the mind and while I love them, I need concentration and thought and spreadsheets to deal with them.
Anyway, we all seem to be in agreement, which is a happy ending.

Mr Bill

Don't underestimate your intuition - a great psychiatrist of the 1970s called fritz perls made this observation ...
(see para 2 ) - http://newregressiontherapy.com/questions.html

DSM

[BrianinTN]

No worries. Thanks for the kind words. After I wrote it I realized it tilted much more forward a formal proof than I had intended. I have a tendency to want to see arguments full and complete with all assumptions and evidence for them cleanly laid out. We'll blame that and my OCD on my secondary education.

Assuming Guess doesn't chime in with something else, I think we're all more or less on the same pages. Or at least reading the same books. Occasionally upside down and in Green.

Anyway, hope Harry Potter was good. The reviews have been excellent!

[NotMuffy]

In addition to the aforementioned issue of deciding what could be wake in the waveforms and therefore somewhere between academic and irrelevant, there is also the preaforementioned issue of the breathing irregularity of phasic REM. And I think that as the REM-suppressant medication effect wears off in the latter part of the night, you have a pile of it (that might be an interesting thing to look for in your raw NPSG data).

You probably want to leave the variability of phasic REM alone (including centrals that are in there. They are generally considered to be normal phenomenon.)

And I tell ya, if the waveforms didn't put that big red block in there to identify PPs, the coarseness of that pressure channel makes everything look like a PP.

Anyway, before I forget what I was going to say...

...

...

Damn.

[NotMuffy]

Can we please just go back to talking about our avatars...

Good idea.

Since that Rapture Thing is like so yesterday, I think I'll go back to my normal avatar.

[NotMuffy]

Oh yeah.

In this area:



breathing looks a little irregular, but that's about it. Because of its location, it could be REM, and the algorithm has opted to bang on it with some IPAP. Was the first one justified by some FL characteristic? The response Is a breath late, and anyway, it just looks a little noisy to me, and perhaps artifactual.

[NotMuffy]

The last couple of DLs with AHI 9.0 - 10.1 are certainly a vast improvement over the 19.0 - 36.0.

Regardless of what the future dial wingin' brings, I think it's very important to keep in mind the priorly preaforementioned points-- that because of at least 3 factors, your underlying sleep architecture is probably fragmented. Not horrifically so, but I think you're drifting over and under the 100 arousals/night threshold that tends to predict the incidence of EDS (don't bother to Google that-- I made it up)(with some scientific rationale, however).

And if, after all the dial wingin', there's still evidence of that (in ASV Mode, that could be non-PTB. Just because an ASV attack makes the waveform look good doesn't mean your sleep continuity is improved. In the case of a post-arousal event, it doesn't matter what the machine does. The potentially EDS-producing event has already happened) then the next steps would be to optimize the factors that affect sleep continuity.

For instance, sitting down with a sharp pharmacist and looking at drug hygiene may be helpful (if that hasn't already been done). Stuff like looking at nighttime duloxetine dose and seeing if that's the best way to meet goal (does the lowering of arousal threshold create more issues than amelioration of other symptoms). Or if anything can be done with the methylphenidate - modafinil thing.

Of course, drug wingin' certainly has it's risks. An abrupt baclofen - duloxetine discontinuance would undoubtedly result in something that looks like the final scene in Total Recall (I know you know that, but I'll bet more than a few others don't).