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Worth trying to lessen flow limitations?
#1
I'm still not feeling brilliant after 3 months CPAP - the latest possibility on my hit-list is flow limitations, but I am not sure if they are significant enough to bother with?
I see lots of little flow limitations all night on the graph (attached), but 95% is reported at only 0.05. I never get RERA's.

Current pressure 7-12, EPR2, Resmed Autoset 10
Last 30 days average RDI 0.9 average pressure 8.1, 90th centile 9.3, average major leaks 0.7%

My plan was to change EPR to 3 , and raise minimum pressure to 8 or maybe 9, and watch centrals don't get higher than the current average of 0.7. Is that the correct way to approach this? Am I barking up the wrong tree?


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#2
Hi Carbon,
As far as Flow Limitations, they are fairly low. I don't see a concern there.

I'm not sure if your machine reports RERAs, you can go into preferences and change RDI to AHI. You'll get the same number, because there are no RERAs, or your machine doesn't report them.

I would 't change EPR to 3, unless the exhalation pressure bothers you. The higher EPR has been known to cause more clear airways. In time, you may want to work your way down to EPR of 1.

Your numbers are very good, but you do need to watch that Centrals are 't the majority of the apnea events.

Raising the minimum pressure by .5 at a time is best, and then watch your numbers. The max pressure is fine. Also, if you don't need the ramp, I would turn it off.

The other thing you need to watch is your leak rate. It's not bad, but try to address mask leaks, or mouth breathing and correct that.

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#3
Thanks OpalRose

Interesting what you say about my machine not reporting RERA's - I did not know that. The loaner Autoset 10 did report them, albeit averaging only 0.2, and I had assumed my new Autoset did also since it looks identical. It seems the loaner was a "for her" in disguise.

I bumped up the minimum to 8, and the pressure variation curve for the night flattened out markedly, which looks nice.

I just use autoramp to stop sensation of ear pressure while going off to sleep - it usually ramps up after 5-15 minutes without me noticing so I guess it is picking me drifting off to sleep pretty well.
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#4
(03-18-2016, 07:55 PM)Carbon Wrote: Thanks OpalRose

Interesting what you say about my machine not reporting RERA's - I did not know that. The loaner Autoset 10 did report them, albeit averaging only 0.2, and I had assumed my new Autoset did also since it looks identical. It seems the loaner was a "for her" in disguise.

I bumped up the minimum to 8, and the pressure variation curve for the night flattened out markedly, which looks nice.

I just use autoramp to stop sensation of ear pressure while going off to sleep - it usually ramps up after 5-15 minutes without me noticing so I guess it is picking me drifting off to sleep pretty well.


Just to clarify, I remember someone saying that some of the newer ResMed machines reported RERAs like the "for her" models, but not sure. Dont-know

Good luck with therapy. Sleep-well
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#5
It doesn't seem to report RERA's. The few I was getting completely vanished from the time I switched from the loaner.
There is no date of manufacture on it - I got it 3 months ago but maybe its older if (as per sticker) it made a round trip from being manufactured Aus to the distributers in CA and back to Aus again.
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#6
(03-18-2016, 09:19 PM)Carbon Wrote: It doesn't seem to report RERA's. The few I was getting completely vanished from the time I switched from the loaner.
There is no date of manufacture on it - I got it 3 months ago but maybe its older if (as per sticker) it made a round trip from being manufactured Aus to the distributers in CA and back to Aus again.

Hi Carbon,

It is possible you haven't been having any RERA events. Or, if your A10 AutoSet is not one of the newer ones which are capable of scoring RERA events, perhaps your true RDI would be higher than reported.

I think you could call ResMed Customer Service to find out whether your machine's serial number indicates it does/doesn't report RERA events. (You could ask whether there is an easy way to tell the difference, such as perhaps a different REF# on the back on A10 AutoSets which do score RERA events, and let the forum know.)

By the way, your Leak varies quickly, which can fool the machine into scoring a CA when what happened was just a rapid change in the Leak.

I suggest zooming in on the Flow waveform near each of those few CA events to see of they are even real. I suggest zooming in until a minute fills the screen, and adjusting the amplitude scale of the Flow waveform to perhaps -60 to +60 to allow you to see fine detail near the zero axis.

When the Leak rapidly jumps or drops, this throws the Flow waveform off of its zero axis for a while, so that our inhales and exhales may not cross the zero line for several breaths. The Flow crossing its the zero line, is how the machine distinguishes between inhale (positive Flow) and exhale (negative Flow). So until the machine finishes slowly recentering the Flow waveform back onto its zero axis, the machine may not see our changes between inhalation and exhalation and may mistakenly score a CA.

In any case, even if the few CA reported were all real, see how long they are lasting. If less than 15 seconds they may not be causing a significant amount of O2 desaturation, and if a CA is starting and ending smoothly and gradually they are probably not causing a sleep-disturbing arousal.

I think a few centrals which are not lasting long may be less disruptive to sleep than RERAs (which are caused by respiratory effort and, by definition, include a sleep-disturbing arousal).

So I suggest not being afraid of increasing EPR to 3 for a week or two to see if, on average, you start feeling a little better and more rested in the morning, or the opposite.

Take care,
--- Vaughn.



Membership in the Advisory Member group should not be understood as in any way implying medical expertise or qualification for advising Sleep Apnea patients concerning their treatment. The Advisory Member group provides advice and suggestions to Apnea Board administrators and staff on matters concerning Apnea Board operation and administrative policies - not on matters concerning treatment for Sleep Apnea. I think it is now too late to change the name of the group but I think Voting Member group would perhaps have been a more descriptive name for the group.
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#7
Thanks Vaughn
There are generally no leaks around the time of CA's. I can't find any with the baseline shift problem you describe. I do usually get 3-4 CA's/ night lasting 18-20 seconds, but the rest are only 1-2 seconds and I can't even see them in the waveform, so I'm not sure what thats about - some sleepyhead glitch?

Some of the "real" CA's are preceded by a deep breath, so may be just REM sleep. "Real" CA's probably just a couple at night.

I was raising the Flow limit thing as I was wondering if I might have UARS rather than OSA to account for still feeling ordinary despite over 2 months of AHI <1. My initial sleep study was poor quality in that I barely slept (~80 min light sleep, 10 min deep, no REM = ? how valid), almost all events were hypopnoeas, I don't snore, and used to think I slept pretty soundly. I had a subsequent titration study which found my APAP (at that time 7-14) was fine - I don't know if it specifically looked for UARS

I was reading Barry Krakow's stuff from 2007. UARS: A Critical Link to Optimizing PAP Therapy Results. Krakow's article is old, and I cant see anywhere his theory about UARS waveforms and sleep disruption has been confirmed on EEG - and I wonder whatever he is on about back then has been subsumed by RERA/ RDI reporting? Or maybe not?

I looked at my flow rate waveform - to me it looks "notchy" aka Krakow's observations. In the absence of RERA reporting from my machine, I have turned on Sleepyhead User defined flow limitation of 20% for 8+ seconds assuming it is some sort of surrogate for UARS - I average 1/ hour.

So putting all that together I guess I should gradually try to move lower pressure up to at/ just under 90th centile (9 for me), with EPR left at 2, and watch what happens to CA's - if they worsen, reduce EPR, if all sweet, increase EPR to 3 as per the UARS theory. Then if still not improving, maybe talk to my respiratory guy about maybe trialling auto BIPAP?

Of course it may yet prove my periodic leg movement index >50 is the problem - so many moving parts to address - one thing at a time Smile
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#8
(03-20-2016, 12:00 AM)Carbon Wrote: I was reading Barry Krakow's stuff from 2007. UARS: A Critical Link to Optimizing PAP Therapy Results. Krakow's article is old, and I cant see anywhere his theory about UARS waveforms and sleep disruption has been confirmed on EEG - and I wonder whatever he is on about back then has been subsumed by RERA/ RDI reporting? Or maybe not?

I think RERA and RDI reporting essentially addresses the subject of Dr. Krakow's work.

"A reminder that for all practical purposes, the following three terms are interchangeable:
· UARS (upper airway resistance)
· Flow limitation
· RERAs (respiratory effort related arousals)"

The above quote is from Dr. Krakow:
http://www.apneaboard.com/forums/Thread-...-and-BiPAP

Quote:So putting all that together I guess I should gradually try to move lower pressure up to at/ just under 90th centile (9 for me), with EPR left at 2, and watch what happens to CA's - if they worsen, reduce EPR, if all sweet, increase EPR to 3 as per the UARS theory. Then if still not improving, maybe talk to my respiratory guy about maybe trialling auto BIPAP?

Sounds like a reasonable plan.

An Auto BiPAP is the optimal machine for treating purely obstructive events like RERA.

BiPAP does tend to worsen the number of centrals we get, for those of us who are susceptible to centrals, but I think how we feel in the morning and throughout the day is a better measure of treatment efficacy than how many centrals we get.

Some Apnea Board members have reported they feel best when their APAP Min Pressure is raised to essentially equal their average measured max pressure. Perhaps these were unrecognized RERA sufferers before they raised their own pressures?

Quote:Of course it may yet prove my periodic leg movement index >50 is the problem - so many moving parts to address - one thing at a time Smile

Seems likely.
Membership in the Advisory Member group should not be understood as in any way implying medical expertise or qualification for advising Sleep Apnea patients concerning their treatment. The Advisory Member group provides advice and suggestions to Apnea Board administrators and staff on matters concerning Apnea Board operation and administrative policies - not on matters concerning treatment for Sleep Apnea. I think it is now too late to change the name of the group but I think Voting Member group would perhaps have been a more descriptive name for the group.
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#9
Just to report how all this went - I gradually increased pressure to minimum 9.4 being about my 90th centile, but then backed it off to 9 minimum as I was starting to develop aerophagy.

Overall the increase in minimum from 7 to 9 did seem to feel better. I have left EPR at 2. AHI averaging 0.7

I had expected to see my pressures mostly trundling along a flat line at the minimum pressure of 9 since my average previously was only 8.4. This was not the case - my pressures rarely sit on the new higher minimum, and overall pressures are significantly higher, with my 90% pressure is now 10.8 vs my previous 9.4.
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#10
(03-18-2016, 08:03 PM)OpalRose Wrote: Just to clarify, I remember someone saying that some of the newer ResMed machines reported RERAs like the "for her" models, but not sure. Dont-know

Good luck with therapy. Sleep-well

OpalRose, I have just (last week) gotten my AirSense 10 Autoset and it reports RERAs.

Frank
I am not a Medical professional and I don't play one on the internet.
Started CPAP Therapy April 5, 2016
I'd Rather Be Sleeping
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