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"REM-Related" Sleep Apnea
#11
(04-17-2017, 08:29 PM)Sleeprider Wrote:
(04-17-2017, 08:08 PM)thecpapguy! Wrote: After writing this up and posting it, I've gotten some feedback, and they are trending to exactly what you are saying! The Respironics and Fisher/Paykel auto-paps do no increase or lower pressure fast enough, while the Resmed treats much more quickly. I am trying to find some controlled clinical trials or any study data that may indicate that the Resmed algorithm is optimal in auto concerning "REM-related" events.

I have what you're looking for, but note that Resmed sponsored partial funding for this study. http://openres.ersjournals.com/content/1/1/00031-2015 

You can recognize the Resmed algorithm compared to the others very readily.  The purple and blue lines are both Resmed standard and soft responses.

Sleeprider, that study is fantastic!! Thank you very much for giving my that information. I saved it. 

That is what I expected in that the Resmed machine would adjust much more quickly making it available to compensate for REM OSA. I can't believe how quickly that study indicates that the device adapted to such elevated pressures exceeding 16 cm/H2O! In less than 10 minutes the pressures were incredibly high. We can't even titrate pressures that quickly in an in-lab. titration study! What are your thoughts on that concerning REM OSA? 

Just glancing through the study last night and pondering it I was thinking that with the Resmed Airsense Auto the algorithm is going to be able to adjust adequately, but maybe it would over titrate?
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#12
(04-19-2017, 12:27 AM)quiescence at last Wrote: I found that during some periods in the night I show a different breathing pattern than at others, and have come to believe these are while I am in REM sleep.  While I am in those periods, my breathing is more erratic, but does not trigger many event counting.  I have seen others that Geiger out during transition to those same periods.  I am sure glad I am not suffering that, and sorry for those that do.

There are some studies that found that breathing feedback loops become less sensitive or somewhat lethargic during REM sleep.  So, for example, the amount of CO2 can rise a bit more before the brain whispers breathe.  Breathing can become shallow and a bit more rapid (TV may drop as much as 20%, but MV usually remains nearly constant.)

Hope this idea finds some application in your current work.

Do you know what is the initial trigger for REM related apneas, and are they mostly OA or CA?

Thanks,

QAL

QAL, I'm honestly unsure of what the initial trigger would be. REM stage apnea seems to be very fickle. In my observations wherein one patient their apneic events subside to nothing in REM, in others it may be substantially worse (the latter is more common). If I was to make an assumption it is likely due to the amount of atonia and suppression that the body goes through while in REM sleep. With muscle tone very low and the body virtually paralyzed you can imagine how that can impact the airway. Due to the suppression caused from the atonia, the breath pattern becomes very erratic, and the diaphragm is stressed much more coinciding with exactly what you reference in the rise in CO2. 
I truly am unsure if there is a definitive cause for what causes events to increase in REM. Sorry!
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#13
Cpapguy, the rapid adjustment of the Resmed Autoset is a key feature that enables the use of wide-open pressure (4-20) on untitrated patients; however, we know the algorithm can indeed over-react to a higher pressure than needed in some individuals. As an understanding of a person's pressure needs evolves, my recommendation (aka rule of thumb) is to increase the minimum pressure to be at least equal to the median pressure, or if you want to get technical, to 70% of the 90th percentile pressure. That means someone with a 90% pressure of 10, should set the minimum to 7.0, or if the max pressure is 20, the minimum should be 14. This improves response and can help to avoid over-response. It is also much less disruptive than large swings in pressure.

Resmed can increase pressure rapidly and it tends to hold that pressure longer than machines that use a slower, less aggressive algorithm. With Philips we often see a machine that eventually reaches a therapeutically effective pressure, but the algorithm's preference to reduce pressure back to the minimum results in hypopnea or flow limitations which then increase pressure again. With Phillips my rule of thumb is to increase minimum pressure to about 80% of the 90% pressure. Both machines are optimized very similarly, but the slower machine must be set with a minimum pressure closer to the 90% pressure, which is usually the ideal CPAP titrated pressure.

The whole notion that a machine is automatic, and does not need to operate within a narrow effective range needs to be debunked, even among professionals. An optimized minimum pressure really needs to be looked at within the first few weeks or a month of starting therapy. Finally, something that study did not evaluate is the impact of EPR. Especially on fixed pressure CPAPs, the use of EPR can move the EPAP pressure out of the effective treatment range of an individual, or in others, cause CA events. EPR as implemented by Resmed is a bilevel with a pressure support capability up to 3-cm. The mask pressure curves are identical with the Aircurve and Autosense machines.
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#14
Overcompensation is probably why the For Her algorithm works better for me than the standard Resmed algorithm. That would also explain why my pressure goes higher with the regular algorithm.
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#15
(04-17-2017, 02:56 PM)thecpapguy! Wrote: Article:

REM-Related Sleep Apnea?

[Image: SleepStageChart.png]

I disagree with The description of N3 and N4 sleep stages in your table. I have seen sleep tests including my own where there have been plenty of events but no time in N3 or N4. I have seen other test results with plenty of events with time in N1 and N2 and REM. While i have not seen that many sleep test results, I do not see how one could possibly say that N3 and N4 are the only stages wherein apnea events occur and that is what the table indicates..

Best Regards,

PaytonA
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#16
(04-22-2017, 07:08 PM)PaytonA Wrote:
(04-17-2017, 02:56 PM)thecpapguy! Wrote: That table is actually data from an older AASM scoring manual. Stage four sleep is no longer considered a stage of sleep anywho. I had it saved from a long time ago that I used in a presentation. I think I'll try to get an updated one made to put on this post. 
Thanks!

Article:

REM-Related Sleep Apnea?

[Image: SleepStageChart.png]

I disagree with The description of N3 and N4 sleep stages in your table. I have seen sleep tests including my own where there have been plenty of events but no time in N3 or N4. I have seen other test results with plenty of events with time in N1 and N2 and REM. While i have not seen that many sleep test results, I do not see how one could possibly say that N3 and N4 are the only stages wherein apnea events occur and that is what the table indicates..

Best Regards,

PaytonA
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#17
(04-21-2017, 08:20 AM)Sleeprider, Wrote: Cpapguy, the rapid adjustment of the Resmed Autoset is a key feature that enables the use of wide-open pressure (4-20) on untitrated patients; however, we know the algorithm can indeed over-react to a higher pressure than needed in some individuals.  As an understanding of a person's pressure needs evolves, my recommendation (aka rule of thumb) is to increase the minimum pressure to be at least equal to the median pressure, or if you want to get technical, to 70% of the 90th percentile pressure.  That means someone with a 90% pressure of 10, should set the minimum to 7.0, or if the max pressure is 20, the minimum should be 14.  This improves response and can help to avoid over-response.  It is also much less disruptive than large swings in pressure.  

Resmed can increase pressure rapidly and it tends to hold that pressure longer than machines that use a slower, less aggressive algorithm.  With Philips we often see a machine that eventually reaches a therapeutically effective pressure, but the algorithm's preference to reduce pressure back to the minimum results in hypopnea or flow limitations which then increase pressure again.  With Phillips my rule of thumb is to increase minimum pressure to about 80% of the 90% pressure.  Both machines are optimized very similarly, but the slower machine must be set with a minimum pressure closer to the 90% pressure, which is usually the ideal CPAP titrated pressure.

The whole notion that a machine is automatic, and does not need to operate within a narrow effective range needs to be debunked, even among professionals.  An optimized minimum pressure really needs to be looked at within the first few weeks or a month of starting therapy.  Finally, something that study did not evaluate is the impact of EPR.  Especially on fixed pressure CPAPs, the use of EPR can move the EPAP pressure out of the effective treatment range of an individual, or in others, cause CA events.  EPR as implemented by Resmed is a bilevel with a pressure support capability up to 3-cm.  The mask pressure curves are identical with the Aircurve and Autosense machines.

I agree with what you are saying and I think it is common knowledge inside of the field, but I can't find many controlled studies giving evidence that it can happen. I whole heartedly understanding your pressure setting theories and that is exactly how I recommended pressures. However, that does not stop the stance that many people are probably given autoPAP with the pressure settings left wide open as "optimum." I think that is where my motive for concern comes from.
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