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

[-SWS]

I think SV could be particularly helpful when the flow limitations show temporal variations. Many people with UARS have "cyclical" flow limitations. The optimal pressures between these cycles versus during the cycle would be different. Furthermore, the cycles themselves get progressively worse as the night goes on. The cycles happen to occur when my body is trying to get into level 3/4 sleep. At those points, the flow limitations are worse than when I am in level 1/2 sleep.

So how would you compare that time window of downward-skewing UARS flow reductions to that of various gradual downward-skewing hypoventilation syndromes? Is it ever sustained by more than a few minutes?

The reason I ask is because hypoventilation syndromes are contraindicated for SV's very short time-window approach of recent-averaging flow targets. So will that short several-minute time window of SV's recent-average flow-targeting really suffice for algorithmically correcting the gradual and at times sustainable downward flow skews of UARS? Because they sure don't suffice for the more gradual and sustainable hypoventilation syndromes according to SV manufacturers' contraindications.

The inherent problem with Resmed and Respironics SV technology: under-addressed sustained downward flow-skews can prolifically be averaged, targeted, and repeated throughout a sleep session. The Weinmann SV/APAP hybrid implementation should be pretty interesting to keep tabs on IMHO.

[-SWS]

The inherent problem with Resmed and Respironics SV technology: under-addressed sustained downward flow-skews can prolifically be averaged, targeted, and repeated throughout a sleep session.

The above summary speaks of a possible flow-targeting problem if a significant and sustained stepped impedance function typical of UARS exceeds an SV machine's very short flow-averaging and targeting time-window. That type of situation is one reason why Resmed and Respironics explicitly ask that an obstructive component (UARS in this case) be manually addressed by a fixed pressure bias before allowing SV to ventilate. Unlike OSA-targeted APAP machines and even the Weinmann SV, neither the Resmed nor the Respironics SV machines are capable of performing obstructive event detection.


But here's where an adapt/auto SV trial becomes much more compelling for UARS IMHO:

At that point [14 cm], FL decreased but I started getting a few central apneas. They believe I have UARS, with a very mild case of complex apnea. So, now they are going to titrate me on an ASV machine with bi-level pressure. The ASV will help fight the central's at higher pressure, and they also said it would help round out the breathing.

While I personally don't see that SV is a shoe-in as a general UARS treatment method, I think SV can help with those emergent or complex central apneas while also treating UARS with a manually-titrated fixed pressure bias (that is assuming fixed BiLevel can't manage to address the emergent central component as well as SV). However, I honestly think following Resmed's and Respironics' recommendations of first manually titrating away the obstructive component (UARS in this case) is very wise. I'm sure that's what your doctors had in mind anyway, gobears.

Good luck!

[dsm]

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

Couldn't agree more. Also, in respect to flow limitations, I think SV could be particularly helpful when the flow limitations show temporal variations. Many people with UARS have "cyclical" flow limitations. The optimal pressures between these cycles versus during the cycle would be different. Furthermore, the cycles themselves get progressively worse as the night goes on. The cycles happen to occur when my body is trying to get into level 3/4 sleep. At those points, the flow limitations are worse than when I am in level 1/2 sleep. I assume the progressively worse conditions happen because I because nasal congestion increases as the night progresses. In any event, I concur with the observation that SV should help with such situations.

Had a good w/e here in Sunny Sydney - hope y'all are enjoying yours

Gobears, good point.

Also to those interested' if anyone wants to start a thread - perhaps called "can an SV machine also handle UARS" then the topic could be discussed there. When I am thinking of UARS I am going by Barry Krakow's definition and that I suspect is where some people will have diverging views.

Anyway - pls can we leave this thread intact as a look at the Weinmann SOMNOvent CR & if there is any interest in SVs & UARS, pls start that as a self contained topic.

Cheers & thanks

SWS - thanks for the info you came up with on the SOMNOvent CR re FOT & its likely use - your input is always appreciated

DSM

[-SWS]

When I am thinking of UARS I am going by Barry Krakow's definition and that I suspect is where some people will have diverging views.

I suspect most of the medical community currently diverge with Dr. Krakow's definition of UARS. In that thread you linked to earlier, Dr. Krakow contended flow limitation was sole criterion for UARS. Not to still sound playful or cheeky.... But I have yet to see other credible researchers claim that. Rather, Dr. Krakow's definition of UARS essentially implicates the entire human population of having either constant or prolifically recurring UARS.

The rest of the medical community who argue for the existence of UARS as a unique condition, tend to stick with what that letter "S" signifies: "Syndrome", which by definition entails an entire constellation of symptoms. So the basis of inquiry for most of the medical research community embracing UARS as a possible medical condition seems to be built on that central premise of extensive symptomology---and not just flow limitations. Then based on that more extensive UARS symptomology, various characteristic/candidate etiologies, pathologies, pathophysiologies, and treatment methods are typically considered that extend beyond the premise: "You have flow limitations: therefore you have UARS". I mean no disrespect to Dr. Krakow, because I think his position may actually be tenable, although I personally disagree with it. Then as gobears stated, many in the medical community do not even think that UARS, as a unique condition, exists. Rather some contend that UARS is simply a variant or lesser severity of obstructive SDB failing to meet any criteria as either a unique condition or symptomatically-based syndrome.

So I personally think it would be next to impossible to syllogistically determine if SV can successfully treat UARS with that grotesque lack of understanding in the medical community regarding just what UARS might or might not be.

However, the subject of SV's very narrow recent-averaging time window has come up in light of gobears' own UARS-related sustained temporal variations above. Doug, when you say "good point" are you saying that you think SV's narrow flow-targeting window can consistently and efficiently counter those sustained variations in flow reduction that gobears related above? If so, I have to politely disagree with both of you.

Here is the caveat of short-sighted SV's lacking temporal-variable based flow-maintenance demonstrated:

In another patient, undertitration occurred as the technologist adjusted the EEP for apneas and hypopneas, but did not adequately increase the pressure for residual RERAs.

http://www.sleepreviewmag.com/issues/ar ... -06_03.asp


And if it's okay, I'll paraphrase my above statement to highlight the technology being discussed rather than the manufacturers:

The inherent problem with SV's narrow-time-window based flow averaging and targeting: under-addressed sustained downward flow-skews can prolifically be averaged, targeted, and repeated throughout a sleep session.

Unfortunately, sustained flow reductions that the body does not manage to spontaneously correct on its own, can stay prolifically under-treated when relying on a several-minute narrow flow targeting time window. Again, that's why the manufacturers contraindicate hypoventilation syndromes and that's why the manufacturers ask that the obstructive SDB component be manually addressed with a fixed pressure bias. Otherwise clinicians may run into the situation Dr. Brown describes above.

[dsm]

Just want to add to RestedGals excellent comments on SV technology ... (my comments in blue) ...

i have complex sleep disorderd breathing and a big issue with centrals- i have tried both the resmed and the respironics machines you mention. I tried the respironics first and no matter what changes they tried i had an AHI that ranged from 94 to 104 even though i did feel a bit better than without a machine. I was beginning to think that that was the best we would be able to do and then i was switched to the Resmed and my AHI is 0.2 and AI is 0! Despite both machines being aimed at dealing with the same problems and sounding like they deal with it in a similar way i can say that they feel very different indeed from my point of view- when i was talking to the DME about it she said that they found some people did better with one and some the other, very few get similar results with both machines which i find very interesting.

kebsa, I've put in bold red a couple of things in your post that make me be not surprised at all that you get better results with the ResMed ASV than you did with the Respironics SV -- for your particular type of sleep disordered breathing.

As I understand it (limited understanding, of course) the ResMed ASV was designed primarily to treat central sleep apneas. Particularly to deal with the centrals that associated with Cheyne-Stokes respiration in CHF (Congestive Heart Failure) patients. It is most likely the champ at dealing with significant centrals in general.
Here I sort of agree but in fact Resmed introduced the 1st SV in 2001 ( called it the Autoset CS (for Cheynes Stokes) and it was in a Sullivan style case http://www.talkaboutsleep.com/sleep-dis ... utoset.htm ). Centrals were and have been successfully dealt with already when Respironics introduced their 1st Bipap S/T in the late 1990s. Centrals in any machine, including the SV machines, are dealt with by an algorithm that drives alternating pressures, cycling at a breathing back-up rate. The two pressures being epap & ipap, the wider to gap between epap & ipap (up to a point) the better the effect in getting the sleeper to breathe again. The machine can't force the sleeper to breath but the alternating pattern tries to 'induce' resumption of breathing. Actually, ASV machines were designed to specifically target fluctuating respiration that is what the name 'Servo Ventilation' represents - Centrals are not addressed with Servo Ventilation but as explained, with cycling pressures. Servo Ventilation tracks volume or peak flow and adjusts inhalation pressure to try and smooth out respiration, if, during the hypo-ventilation phase of Cheynes Stokes, or Complex Apnea or Mixed Apnea, a central occurs then the Servo Ventilation gives way to the cycling algorithm that then works to get the sleeper breathing again. In Summary, the 1st SV machines (Resmed in 2001 & Respironics in 2002) were specifically designed to normalize irregular respiration as characterized by Cheynes-Stokes with its waxing and waning patterns. Mixed & Complex Apnea are beneficiaries of that achievement. Centrals = Cycling pressures at backup rate. SV = normalizing irregular respiration (best characterized by CS).

Both machines (ResMed ASV and Respironics Bi-PAP Auto SV) are not aimed at dealing with exactly the same problems, imho. The ResMed machine is aimed primarily at treating centrals. The Respironics machine is aimed at primarily (imho) treating obstructive apneas and handling centrals as a secondary goal. There's a difference, in my mind, as to the "main" treatment aim of those two machines. But I may not be understanding them well.

Both the Resmed & Respironics machines were in fact originally designed for the same Cheynes-Stokes patterns. But Respironics chose a different approach (Peak Flow targetting vs Volume targetting in the Resmed) which allowed them some flexibility on how the machine could be used & they added extra features that give the machine an extraordinary variety of configurations. The downside of that is the machine is very much easier to misconfigure.

I think there are probably considerable differences in the way those two machines are designed to deal with centrals.
Centrals are dealt with in an identical manner between the Resmed & Respironics machines - they both revert to cycling between epap & ipap at a back-up rate. This is the same principle used in Bipap S/T machines & that has not changed. The major difference between the Resmed & Respironics is the shape of the waveform. Resmed changed theirs to a shark-fun pattern as that more closely mimcs human breathing. Resmed took that waveform pattern and added it to EPR (called Easy Breathe) & that is why the upgraded version of EPR is such a good feature to have in a cpap.

So, again, I'm not surprised that the machine, which has as its primary design emphasis, treating centrals is the machine that you get good results from -- since you said central apneas were a very big part of your diagnosis.

Sounds to me like you already have the right machine for your particular type of sleep breathing disorder, kebsa. Hope all keeps going better and better for you. You certainly have a lot on your plate to deal with besides SDB.

I was glad to see -SWS, whom I consider to be, by far, the most knowledgeable person on this board about how all these machines work and what they are designed to best treat (insofar as anyone who is not directly involved in the actual design at the companies can be) bring his carefully considered thoughts into this thread.

RG we all respect SWS, he contributes excellent insights & thoughts to most of the discussions he participates in. A highly valued member of cpaptalk - so what prompted such a cheerleader outburst you probably would look very cute in a cheerleader outfit - twirling pompoms & baton - lucky SWS

Cheers DSM

Links to the early Resmed & Respironics developments

Respironics called their machine the HeartPap - designed specifically for periodic breathing associated with CHF and CSR
http://www.touchcardiology.com/files/ar ... Wensel.pdf

Resmed called their machine the Autoset CS specifically designed for CSR associated with CHF
http://www.talkaboutsleep.com/sleep-dis ... utoset.htm

[dsm]

Doug, when you say "good point" are you saying that you think SV's narrow flow-targeting window can consistently and efficiently counter those sustained variations in flow reduction that gobears related above?
If so, I have to politely disagree with both of you.

Here is the caveat of short-sighted SV's lacking temporal-variable based flow-maintenance demonstrated:

In another patient, undertitration occurred as the technologist adjusted the EEP for apneas and hypopneas, but did not adequately increase the pressure for residual RERAs.

http://www.sleepreviewmag.com/issues/ar ... -06_03.asp

Did I just get someone else's words put into my mouth - then get replied to before I even had a chance to refute
How cute

DSM

[-SWS]

Did I just get someone else's words put into my mouth

I honestly don't think anyone put words in your mouth, Doug. Please see my querying words below.

Doug, when you say "good point" are you saying...? If so,

Rather the above words really ask what point you were agreeing with. Were you agreeing with gobears' central point that SV should automatically address his sustained flow-reduction cycles? Then I went on to describe a key caveat of narrow-window flow averaging and targeting that would not always lend an efficient method of addressing those sustained temporal variances gobears described.

I don't think it's odd at all that I should ask if your words "good point" were in agreement with gobears' central point in what you had quoted. Wasn't that an even better guess than asking if your words "good point" were merely aimed at the sentiment expressed by the words "I fully concur" (instead of gobears' central point)?

[rested gal]

RG we all respect SWS, he contributes excellent insights & thoughts to most of the discussions he participates in. A highly valued member of cpaptalk - so what prompted such a cheerleader outburst you probably would look very cute in a cheerleader outfit - twirling pompoms & baton - lucky SWS

Doug, for several years I've read your posts --full of techie-babble, full of what you call your "experiments" with machines, full of leaps to wrong (imho) conclusions. That's ok. You're having fun.



Every once in awhile, however, I feel a little uneasy at the thought of how many people new to "CPAP" see your posts and may think, "Ah, this is obviously a fellow who really understands what makes these machines tick. A hands-on expert since he actually uses them and writes at such great length about them."

So, every once in awhile I feel like voicing my personal opinion about who is more likely to be correct when "who corrects whom" in his trademark gentle manner...often with humor...always taking great care to not hurt anyone's feelings. I have a lot of patience, but not as much as -SWS has.

We all can be mistaken about some of our opinions and conclusions. I know I certainly am wrong many a time.

We all make our own decisions about who probably knows what they are talking about when it comes to all these machines.

I remember well how it was when I was getting started and knew nothing about "cpap, autopap, bipap." Diving into the apnea message boards that existed before cpaptalk was started. Before "cpap" was a glimmer in your eye, Doug. Reading, reading, reading -- trying to figure out what machine I should buy. Trying to figure out whose opinions seemed soundest. That's when I first came across posts by -SWS.

Lest there be any mistake, let me be clear. I'm never averse to reading all kinds of opinions about machines, SDB treatment, etc. I think it's great that there's such diversity on this forum. I thoroughly enjoy reading even the most "technical" discussions of opinions whether I understand all of it or just parts of it.

I like to add my opinion, occasionally, about who I would listen to when there's a difference of opinion. Particularly in regard to technical matters with these machines. And what they are likely to treat well -- and not treat so well.

That's what I'm doing now. Just my opinion.

[dsm]

That's what I'm doing now. Just my opinion.

Rested Gal,

In Debating 101 at University, if the 1st speaker for the Red team got up and said. The captain of our team who you will hear from shortly, is the best person I have ever heard on the current topic and better than anyone else (including anyone on the Red team) than sat down. That speaker would win no points at all because basically they made none.

If also the captain of the Red team then stood up and were to say " I don't need to debate x point because I don't have anything to prove", both would be laughed off the stage.

In any discussion, let each party make their points and give credit to the audience and the judges to form their own opinion based on the logic and facts presented. I would hope that any discussion here can be won with winning arguments. I don't think that last point in your post supports this notion.

I believe we have a great forum here & a lot of smart people who can very quickly sort the chaff from the wheat in any discussion. Let them do so

Cheers

Doug

PS your contributions are always great but I don't always agree with all your conclusions - particularly some on technical matters & I hope I have learned (using SWS as a good example) to argue my points politely - I know I have not always done that but I am learning

PPS cute little bub in your piccy - I should be so lucky - my oldest granddaughter will be delivering in 3 days - very exciting times in my familyb

[-SWS]

This is a debate ?

I thought we were exchanging opinions. But I still have a central point up there in relation to gobears' comment that SV should be able to automatically address his sustained flow-reductions. My central point was that since SV relies on such a narrow time-window for flow averaging and targeting---- that gobear's sustained flow reductions may not be very efficiently addressed by the SV algorithm after all. The two SV algorithms that may be superseded by Weinmann's hybrid approach have absolutely no maintenance of temporal variables to automatically cope with sustained downward flow skews. And those two SV algorithms have no obstructive flow-limitation event detection to offset that narrow time-window shortcoming either.

And I also think that's on topic for this thread's subject line. Gobears will apparently have sustained "stepped" upper-airway impedance deltas, thereby reducing flow, flow-averaging, and flow targeting throughout the night. That narrow averaging and targeting window can put his sustained flow reductions at risk of being averaged, targeted, and repeated throughout the night.

Anyone have any comments about what I think deserves to be discussed as a central point, even more than the recent "who said what, why, and exactly how they said it"?

[dsm]

This is a debate ?

I thought we were exchanging opinions. But I still have a central point up there in relation to gobears' comment that SV should be able to automatically address his sustained flow-reductions. My central point was that since SV relies on very narrow time-window for flow averaging and targeting----and that gobear's sustained flow reductions may not be very efficiently addressed by the SV algorithm after all. The two SV algorithms that may be superseded by Weinmann have absolutely no maintenance of temporal variables to automatically cope with sustained downward flow skews. And those two SV algorithms have no obstructive flow-limitation event detection to offset that narrow time-window shortcoming either.

And I also think that's on topic for this thread's subject line. Gobears will apparently have sustained "stepped" upper-airway impedance thereby reducing flow, flow-averaging, and flow targeting throughout the night. That narrow averaging and targeting window can put his sustained flow reductions at risk of being averaged, targeted, and repeated throughout the night.

Anyone have any comments about what I think deserves to be discussed as a central point, even more than the recent "who said what, why, and exactly how they said it"?

Steve,

Can we take this line over to the thread I just started on SV & UARS. I believe we can do it far better justice there.
I would like this thread to remain as a main discussion point on how the various SV type machines work.

Many thanks

Your good friend & debating / discussion partner

DSM

[-SWS]

Sustained flow reductions in relation to a narrow SV window are extremely relevant to this thread in a most general way. Those sustained flow reductions can even occur because of under-addressed "obstructions" (see subject title). And the essence of this thread was to examine the merit of the one SV machine that can differentiate obstructions and centrals. Honestly, how much more on topic (in a general way) can the shortcoming of a narrow averaging and targeting window be?

That situation isn't even exclusive to UARS:

In another patient, undertitration occurred as the technologist adjusted the EEP for apneas and hypopneas, but did not adequately increase the pressure for residual RERAs.

http://www.sleepreviewmag.com/issues/ar ... -06_03.asp

So why put it in a UARS thread when it very easily meets what this thread supposedly aimed to discuss? Honestly, I'm rather confused by that. Anyway, I think I'm done sharing SV opinions in both threads. I brought up what I think are some key considerations.

Apparently they're just not worded right and they're even sitting in the wrong thread. Getting the right what-to-say and how-to-say protocol for discussion down pat in this thread as waaaaaay too much work for me.

Take care, guys... Please carry on this SV discussion without me. I'll catch up with you guys on a near-future SV discussion.

[dsm]

SWS

Thanks for your input as always. But remember we couldn't get agreement on what UARS is & the man I chose as having some expertise (he runs his own sleep labs & thus seems highly qualified) Dr Barry Krakow, doesn't meet your standards for a common understanding. So the topic was short changed as soon as it got started.

Perhaps we can explore this aspect in another thread at another time when you are available

Cheers & thanks

DSM

PS Steve - just dug out this definition of 'debate' which is very much what I see goes on here all the time - works for me ...

Debate
Definition: To contend for in words or arguments; to strive to maintain by reasoning; to dispute; to contest; to discuss; to argue for and against.

[-SWS]

Well, it might not be a bad idea to eventually have an in-depth thread on "The UARS Puzzle: Does It Exist---If So What Pray Tell Is It?". Generally Dr. Guilleminault at Stanford is acknowledged as the founding father of the term UARS. Dr. Guilleminault and his team at Stanford are generally acknowledged as the mainstream opinion of what UARS is----if you can even call UARS acknowledgment mainstream as gobears pointed out.

What's interesting is that Dr. Krakow's posts frequently mentioned a brief internship studying under Dr. Guilleminault. And yet, the essence of what Dr. Krakow and Dr. Guilleminault formerly and currently have to say about UARS are not at all the same. Is anyone aware of any other researcher besides Dr. Krakow who contends that flow limitations and UARS are one in the same? Dr. Krakow's definition of UARS isn't primarily my own rejection. Rather, it seems to be virtually all of medicine who are at odds with Dr. Krakow's definition of UARS (which doesn't mean Dr. Krakow is wrong). However, I think there's sound basis for this message board to eventually revisit what the rest of the medical community is saying about UARS---the entire variety of opinions, including the views of world renowned Dr. Guilleminault (the father of the term UARS) and his Stanford team.

And again, I'm extremely surprised that a most relevant and general topic discussing SV's short targeting in relation to sustained temporal variances somehow managed to get completely sidetracked by posts objecting to conversational nuances, debating mannerisms, and whether the proper "host thread" was used. Go figure...

Seriously, take care... no hard feelings.

[dsm]

Well, it might not be a bad idea to eventually have an in-depth thread on "The UARS Puzzle: Does It Exist---If So What Pray Tell Is It?". Generally Dr. Guilleminault at Stanford is acknowledged as the founding father of the term UARS. Dr. Guilleminault and his team at Stanford are generally acknowledged as the mainstream opinion of what UARS is----if you can even call UARS acknowledgment mainstream as gobears pointed out.

What's interesting is that Dr. Krakow's posts frequently mentioned a brief internship studying under Dr. Guilleminault. And yet, the essence of what Dr. Krakow and Dr. Guilleminault formerly and currently have to say about UARS are not at all the same. Is anyone aware of any other researcher besides Dr. Krakow who contends that flow limitations and UARS are one in the same? Dr. Krakow's definition of UARS isn't primarily my own rejection. Rather, it seems to be virtually all of medicine who are at odds with Dr. Krakow's definition of UARS (which doesn't mean Dr. Krakow is wrong). However, I think there's sound basis for this message board to eventually revisit what the rest of the medical community is saying about UARS---the entire variety of opinions, including the views of world renowned Dr. Guilleminault (the father of the term UARS) and his Stanford team.

And again, I'm extremely surprised that a most relevant and general topic discussing SV's short targeting in relation to sustained temporal variances somehow managed to get completely sidetracked by posts objecting to conversational nuances, debating mannerisms, and whether the proper "host thread" was used. Go figure...

Seriously, take care... no hard feelings.

SWS

I do appreciate that you have good reasons to question Dr Krakow's defs (also he did make those remarks about 18 months ago). This
whole area of sleep therapy is so fluid.

Steve, I do value what I can learn from you on any of these matters & I'll go do some more homework in this area. You are very good
at giving us heads-up views of these complex matters.

I have no doubt that I have learned a lot more from you than you have learned from me - I just hope you can put up with having all
this wisdom wrung out of you

Cheers

DSM

PS I also think RestedGal's enthusiasm for your POVs is well placed - But, I do like to tease her about it just as she teases me even when
she goes over the top