Clear Airway Apnea = Central Apnea?

[Muffy]

Well, I observe this detection/response sequence in that graph above: 1) pressure increases in response to high airway resistance only after flow also drops, 2) then FOT suddenly detects an airway impedance drop, 3) thus the CPAP pressure no longer increases---but instead performs a very gradual pressure drop. By my take the FOT algorithm is administering the correct pressure response just as soon as airway impedance plummets along with that low flow.

I would want to take a real close look-see as to why the controller has halted pressure increase in the face of Rrs/Zrs whatever they're measuring = 0 (right choice) and yet mask pressure continues to rise for about 40 seconds in what is clearly a central event (wrong choice).



I think this aggressive algorithm would be disasterous in anyone with a CompSAS tendency.

Muffy

[StillAnotherGuest]

I think this aggressive algorithm would be disasterous in anyone with a CompSAS tendency.

Well y'know, that nCPAP scale might be only like a 1.0 cmH2O scale, and be taken somewhat out of context.

SAG

[-SWS]

Well, I observe this detection/response sequence in that graph above: 1) pressure increases in response to high airway resistance only after flow also drops, 2) then FOT suddenly detects an airway impedance drop, 3) thus the CPAP pressure no longer increases---but instead performs a very gradual pressure drop. By my take the FOT algorithm is administering the correct pressure response just as soon as airway impedance plummets along with that low flow.

I would want to take a real close look-see as to why the controller has halted pressure increase in the face of Rrs/Zrs whatever they're measuring = 0 (right choice) and yet mask pressure continues to rise for about 40 seconds in what is clearly a central event (wrong choice).

Well, regardless of that pressure lag, it seemed to be non-problematic for the OSA patients under study:

No significant difference was established with regard to central respiratory events (table 2).

But since those same FOT-based impedance calculations treated obstructive FL, A, and H adequately, I think this overall FOT technique deserves better treatment designation than just techno-glitz:

APAPFOT treatment in either of its modes led to a significant reduction in the number of respiratory disturbances: this can be seen for AHI, obstructive apneas, mixed apneas, and hypopneas.

But I agree with this caveat:

I think this aggressive algorithm would be disasterous in anyone with a CompSAS tendency.

I don't yet have a good feel for this FOT algorithm's pressure aggressiveness in side-by-side comparisons with yet other OSA-targeted APAP algorithms. But generally CompSAS patients should avoid any OSA-targeted APAP algorithm since those patients tend not to fare well with APAP's varying static pressures.



P.S. I'll still try to find those competing theories as to WHY ballistocardiography might be detecting central apneas with excellent specificity but only mediocre sensitivity...

[dsm]

nothing more than techno-flash

What a great phrase.. "nothing more than techno-flash"
That's what dsm's I-so-desperately-wanna-be-regarded-as-an-expert posts bring to my mind so often!
I cringe every time I think about how newcomers who really are trying hard to learn as much as they can about sleep disordered breathing and the treatment machines may read dsm's voluminous mish-mash of "techno-flash" and think, "Wow, this guy must really know what he's talking about."

Then there's "techno-sound" -- -SWS's great posts. Very much recommended reading, imho.

And the muffin gang. 'Cept when it comes to argyle socks.

Happy New Year RestedGal - looks like more of the same-old same-old doesn't it

I don't believe we want to make the mistake of of creating a new religion out of SDB. With high priests & mystical rituals and religious mumbo-jumbo - some of which can be used to awe the masses.

The people who come here are ordinary folk who generally appreciate simplified explanations of what it is that afflicts them and a way to put the complexity into some perspective. I do my small bit to try and break down the complexity, I don't always get it right. If that makes me a wannabe to you, so be it.

DSM

[cotech50]

I just ran a report and looked at my worst night ahi 4.1 but was seeing a trend where the CA numbere were going up from the summary. In looking at the graphs they clearly show the CA issues and some transitioning to higher pressure is occuring at the end of my sleep period. I sometime lie in bed for a s much as 45min b4 I get up and not sure if I am starting to drowse off again or what but this helped explain my higher numbers.

[Really]

Happy New Year RestedGal - looks like more of the same-old same-old doesn't it

That is what I was thinking! Really!!

[rested gal]

Happy New Year to you, too, Doug.

Yep... I do see the "same old, same old" -- in your posts.

I don't believe we want to make the mistake of of creating a new religion out of SDB. With high priests & mystical rituals and religious mumbo-jumbo - some of which can be used to awe the masses.

Don't know where that came from... had nothing to do with what I said.

The people who come here are ordinary folk who generally appreciate simplified explanations of what it is that afflicts them and a way to put the complexity into some perspective.

I couldn't agree more. I'm one of the ordinary people who came here to learn. I still come here to try to learn more, every day.

The danger in issuing a "simplified explanation" of technical matters when you start doing that, is that I've so often seen you not really understand what you are attempting to explain, and so often seen you jump to erroneous conclusions. But you put it out there with a techno-flashy air of "I understand this, and I'm going to explain it to all you new people in a way that's easy to understand." Unfortunately, new people who are seriously trying to learn get a lot of misinformation from you...imho.

Of course, that's part of what goes with a message board forum. There will be good info and bad, all in the mix. It's up to the readers to pick through and decide who is usually giving sound info, who is not, and who is just typing to hear the keys click. All of us make mistakes and get things wrong. I know I do.

I do my small bit to try and break down the complexity

I do my small bit to convey my opinion about who, when it comes to posts about complex technical matters, is worth paying attention to. And who is not. I do that occasionally... to alert newcomers who are seriously trying to learn, before they get toooooo dazzled by the sheer amount of your "simplified explanations."

You like to summarize things in a "simplified" way that's easy to understand. That's good.

Here's my summary about your history of posts, as I've read them over the years here. Just my opinion, of course.
I'd give you...

A for effort.
A for being a good person who is sincerely trying to help people.
C for logical thinking.
D for the "simplified" conclusions you pepper your techno-flash posts with.

I definitely get an F for grammar on that last one.

[dsm]

RestedGal

Nicely said - but I am at a disadvantage when you say my logic is flawed but don't point out
where. We have *all* posted the odd incorrect remark & sometimes the wrong info but that
nearly always gets picked up by others because we are such a diverse group and with a wide
range of talent. You are saying I have misled people, please say where.

One aspect of any forum is that people interact, question, challenge & in the majority of cases
people are able to see the value of any discussion to themselves.

I am one who genuinely admires your take up of knowledge on all things cpap - & you have
earned a well deserved reputation as a champion helper. That is your style & what you clearly
get your positives from & why you come here. I am a questioner & am not afraid to poke &
probe & challenge I will guarantee that many people have benefited from me doing so. We
do not need sacred cows here.

I am sure we all know who the experts are among us and I am merely a very interested & yes
enthusiastic, follower of this very beneficial therapy. I think you are a bit obsessed with your
concern that people will think DSM is some sort of expert. I'll bet most folk just see lots of
interesting threads that usually allow the accurate wisdom of all bubble to the surface no
matter who prompts it there.

DSM

[Rebecca R]

So what's happening by the way of your treated apneas, Rebecca?

I have been really trying to do my homework by doing what is always recommended by people on this forum, get the mask working, take care of leaks, rainout, get the software and reader, read, read,read and learn etc... In doing such, I was researching central apneas thinking I don’t want to induce them by increasing my pressure too much, in the process I stumbled onto this thread and got caught up in the…hmm…highly entertaining, but confusing, antics.

I have not found my ideal Tx pressure yet, and I definitely don’t feel good yet. On the occasional days I slept without cpap (since I started 5 months ago), I wake up feeling the same as when I am on CPAP, with the exception of the severity of morning headaches.

My doc told me to increase pressure from 10 to 12, which almost blew my ears out, so I backed down and started increasing .2 at a time. I am up to 11.6 and fairly comfortable, but have never seen a night with no apneas yet. I have only had my card reader for a short time, but since seeing how ineffective my treatment really was, and what I needed to fix, I think I might finally be getting somewhere.

If you have just a few residual apneas, that's probably not such a big deal…
…..That issue of trying to avoid undesirable pressure increases (in response to centrals) becomes a moot issue with fixed pressure.

Aha! Then shall I stop worrying about it? That is unless something crazy shows up in my results.

Quirky? Okay... I just performed a cursory scan of the avatars and text in this thread and I didn't spot anything quirky---especially in the avatars.
Allegations of quirky... Now THAT'S funny stuff right there... Quirky but funny. Spotted it.

Thanks for the info…serious and otherwise…both are needed.

r

[ozij]

Aha! Then shall I stop worrying about it? That is unless something crazy shows up in my results.

Right.
If you suddenly get more apnea on the new fixed pressure, that's when you should worry.

O.

[dsm]

Re auto adjustment of Epap in the Bipap AutoSV - below is a link to the patent application that 'appears' to cover the Advanced version and includes info on adjusting Epap. Still working through it to locate if any technique is employed to decide if an apnea is CA or OSA. I can't see any refs to FOT, but still have more to read. Para 13 talks of adjusting Epap but does not make it completely clear if it does this in response to Periodic Breathing or to an apnea (but it looks like the BiFlex that is said to be added to the new Bipap AutoSV Advanced).

So for any tech-minded person interested in what goes on inside the Bipap AutoSV & esp the Auto adjusting Epap, this is a good place to start.
But, it may not have the answers re CA vs OSA apneas that I am looking for.

Places to look ...
- FIG 3 (see box 104)
- FIG 8 (shows the delta applied to Epap based on detected severity)
- Prara 13 discusses adjusting Ipap & Epap
- etc:

DSM

#2Interesting - this version of the Bipap AutoSV appears to not have any ca vs osa test (that I could see) but does introduce varying the Epap. It looks a bit like the technique used in the Weinmann SOMMNOVent CR machine which when dealing with the waning phase of CSR, drives Ipap & Epap apart *equally* & when dealing with the waxing phase pulls Ipap & Epap together *equally*, BUT, maintains a separate EEPAP which is the pressure maintained at the End of the EPAP cycle.

I will look even further to see if I can find *any* ref to auto Epap in relation to CA vs OSA.

DSM


http://www.internetage.ws/cpapdata/pate ... tosv-3.pdf

This is what I am searching the patent for (the below mentions use of Auto Epap in the 'Bipap AutoSV Advanced' that distinguishes between CA & OSA) ...

http://bipapautosvadvanced.respironics.com/

[Muffy]

Some recent comments here have made me aware that some readers may take some of my comments literally instead of the spirit in that they were originally intended, and that, in turn, might cause confusion and/or misunderstanding. If I have caused that, I most sincerely apologize. My only intent was that I had hoped my exaggerated opinion(s) would help to spur additional debate, and, eventually, a greater overall understanding and appreciation of the concepts involved.

With that in mind, I would like to go back to my prior statement:

the controller has halted pressure increase in the face of Rrs/Zrs whatever they're measuring = 0

I certainly hope that people did not take my reference of Zrs or even Rrs to literally mean that it actually = 0. Given the effects of inertance, resistance and compliance, even if you were able to remove all components that were actually removable (the patient), you'd still have at least 2 remaining factors, however small, to contend with.

While the oscillating Hz in Weinman vs ResMed might theoretically come a lot closer to Rrs = 0, curve behavior says it gets pretty flat after about 5 Hz so Rrs = 0 was never an option, neither theoretically nor mathematically.

Muffy

[Rebecca R]

Some recent comments here have made me aware that some readers may take some of my comments literally instead of the spirit in that they were originally intended, and that, in turn, might cause confusion and/or misunderstanding. If I have caused that, I most sincerely apologize. My only intent was that I had hoped my exaggerated opinion(s) would help to spur additional debate, and, eventually, a greater overall understanding and appreciation of the concepts involved.

I hope you aren't referring to me, being the newbie making fun of the technotalk. I never take anything literally. Besides it would take a fair bit of research to realize which part was exaggeration.

Kidding aside, I found your posts funny even when I just suspected you had a multiple post-inality. Just wanted to say so.

r

[-SWS]

DSM, many thanks for hosting and linking to that patent description!

Muse Inc. thanks for sharing your CPAP treatment thoughts and experiences as well! I agree that just about every facet of sleep medicine and apnea treatment has a long way to go.

Aha! Then shall I stop worrying about it? That is unless something crazy shows up in my results.

Right.
If you suddenly get more apnea on the new fixed pressure, that's when you should worry.

O.

Ditto the right... But also to add that many people on the message boards seem to report this kind of post-treatment experience:

I have not found my ideal Tx pressure yet, and I definitely don’t feel good yet. On the occasional days I slept without cpap (since I started 5 months ago), I wake up feeling the same as when I am on CPAP, with the exception of the severity of morning headaches.

Your sleep-related breathing, sleep patterns, and overall health have essentially been broken for quite some time now. And you have probably discovered, as many of us have, that fixing all of that can be more involved than simply putting on a CPAP mask at night.

Some people get lucky and discover that everything falls into place once they learn how to sleep comfortably with CPAP. Others discover that CPAP addresses only the first of those three underlined categories. Sometimes we have to work on circadian rhythm issues or sleep hygiene practices in general to get that second underlined category under control. And some of us end up having to address resulting or interrelated health problems such as thyroid disorders, diabetes, or even sleep-disturbing acid reflux disease for example.

Lastly, we are the sum total of all our energy-robbing health problems---whether they are related to apnea or not. As it turns out pain issues have probably robbed my own sleep and daytime energy even more than sleep apnea did over the years. All the CPAP tweaks in the world will never fix that problem. Nor will expertly ignoring that pain during the daytime fix the broken sleep that goes with that pain during the night. So, by all means, get your CPAP optimized and get your sleep hygiene fixed first. Then, if energy still seems a problem, look beyond SDB for possible explanations. Good luck!

[-SWS]

but the subroutine identified cardiac oscillations in the FOT channel (while the airway is CLOSING?)

Well, we might want to revisit those contending theories about cardiac pulsations being more detectable for reasons other than open-airway wave-guiding. I'll see if I can dig them up for more techno-weenie chit-chat fun tomorrow...

there were some other contending theories regarding why ballistocardiography might have been revealing central apneas with such good specificity... And that's where my memory starts to get fuzzy but not even warm. I kind of thought one of those contending theories might have had to do with those cardiopulmonary pulsations or heartbeat somehow being more intense during central apneas compared to obstructive apneas.

P.S. I'll still try to find those competing theories as to WHY ballistocardiography might be detecting central apneas with excellent specificity but only mediocre sensitivity...

http://chestjournal.chestpubs.org/conte ... 3/660.full

Results: No obstructive apnea showed definite cardiogenic oscillations. In four cases, there was a suggestion of oscillation that was not regular enough to be called cardiac. Sixty percent of central apneas showed clear, regular oscillations at cardiac frequency. Cardiogenic oscillations also were seen intermittently during quiet exhalation in apnea-free periods.

There you have the somewhat puzzling basis of that near 100% specificity of measurement for central apneas: those cardiogenic oscillations (in the airflow signal) seemingly never happen during obstructive apneas!

Interesting, are they not? Little acoustic "pulsations" of the heartbeat itself will sometimes show up in the airflow signal for central apneas... But they will never show up in the airflow signal during obstructive apneas. Why is that?

There is continuing debate as to the mechanism of transmission of cardiogenic oscillations seen on the airflow signal. Lemke et al,12 concluded that oscillations were always present in subjects who were awake when the airway was seen to be patent by direct visualization, and were usually present in neonates thought to have central events. Obliteration of oscillations occurred during obstructive events. They concluded that cardiogenic oscillations were an indicator of airway patency but did not verify this during sleep.

Lemke et al thinks it has to do with a central apnea's open airway being able to channel those heartbeats up the airway, past the pharynx, and through the mouth/nose. Obviously that type af accoustic channeling can't happen when the airway is obstructed.

cardiac oscillations in the FOT channel (while the airway is CLOSING?)

Hmmm..... While the airway is closing, huh?

Morell et al11 examined only central apneas and concluded that there was no relationship between cardiogenic oscillations and airway patency.

Open-airway cardiogenic oscillations: Now you see them... Now you don't... Lemke et al and Morell et al seem to observe things differently. So Dr. Rapoport's team attempts to reconcile that seemingly dissimilar information with their own 60% sensitivity findings:

These studies suggest two different ways to explain our 60% sensitivity of finding cardiogenic oscillations in central apnea. First, in accord with the observations of Morrell et al,11 cardiogenic oscillations may not always occur in the airflow signal, even when the airway is patent. Alternatively, in accord with the observations of Lemke et al,12 the central apneas seen in our study may have been a mixture of open and closed airway central events; the 60% sensitivity may represent the percentage of events with an open airway.

Dr. Rapoport's team then goes on to speculate that a patent or open airway might be one of two possible factors in physiology conducive to placing those cardiogenic oscillations in the airflow signal:

Our data further lead us to speculate that transmission of cardiogenic oscillations to the airflow signal may be affected by relaxation of respiratory musculature, in addition to being influenced by patency of the airway. Thus, high muscle tone during respiratory efforts may alter coupling between the changes in volume due to cardiac contraction and volume changes in the airway.

If Dr. Rapoport's conjecture is true, then low muscle tone combined with a not-yet or not-completely closed airway plausibly lends this counterintuitive set of measurement circumstances:

cardiac oscillations in the FOT channel (while the airway is CLOSING?)