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central apnea events???
#1
I'd like some opinions on what's going on in the attached plot.

Pressure is constant at 8.5cm. No snoring is recorded.


You will see that I suddenly take a big breath, then my breathing is disturbed and I eventually end up with some periodic breathing which settles back into more or less normal breathing.

I record audio and right after the big breath I can hear some vocalization (grunt, moan, stretch sound) followed by some creaking of the bed. So it sounds like I've aroused a bit and moved around.

Here's what I think is happening, I'd like to hear some other opinions, questions, etc.

I think I'm having a central breathing event when I take the deep breath. A study was done (you can find it here: http://erj.ersjournals.com/content/4/6/660.full.pdf) which looked at the prevalence of non-obstructive apneas in CPAP patients. 43% experienced a central event like mine. I.e. they were breathing normally and then took a deep breath, often followed by an apnea event. This occurred in NREM sleep and was associated with an arousal. to quote from the article: "Central apnoeas during CPAP administration do not develop randomly during NREM sleep, but their onset is nearly always preceded by an arousal or by a wakefulness period, often concomitant with a short hyperventilation."

I think what I have matches the description because the arousal (intake of breath and vocalization/movement) precedes the reduction in airflow. Note that the respironics sometimes declares that the reduced airflow is an OA, sometimes a FL, sometimes a HA. Sometimes it doesn't flag it at all -- it is variable.

So I think I'm one of those people who sometimes wakes a little and takes a big breath, and moves a bit. The big breath causes hyperventilation, which causes me to reduce my breathing drive, which causes underventilation which causes me to increase my BP and increase the breathing drive, and away we go with an oscillation. Eventually the oscillation settles out. At least that's what it seems to me.

I get similar events every night, sometimes more than others, and at a variety of pressures all of which reduce my typical OA to zero. That is also consistent with the article, which says that the CPAP has no effect on these events.

I also feel refreshed by the sleep.

Some questions:

Do others see similar events?

Should I be doing anything about this? Could this be a cause of my intermittent insomnia?

comments appreciated.

and one other thought. What if my mask is not venting enough and CO2 is accumulating. Could that cause my sudden intake of breath? I doubt it because I don't see a rise in BP or drop in O2 before the breath but I thought I would mention the idea.


[Image: CuCl8Odl.png]

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#2
We sometimes refer to it as sleep/wake junk. While it appears to be a short duration periodic breathing patter, it's not meaningful in your therapy and the desaturation is not significant. There is nothing you can do because it does not respond to pressure, and it is not severe enough to require a more aggressive ventilator.

I have many events that are more severe than this, as do many on this forum. If you want to try something to reduce it, see what adjustments to your EPR setting do. Reduce it to 1 or 0 and see if it trends to be less prevalent.

Kinda like this eh?

[Image: RMV8WJb.png]
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#3
yeah, that's what it looks like!!!! though yours are a little more regular than mine.

thanks, I suspected that it wasn't something to worry about, but it's very, very nice to have confirmation from real CPAP users that stuff like that happens.

What's EPR? do you mean Exhaust Pressure Reduction? if so, I went from AFLEX at 3 (which was really fun, I ended up fighting the machine until the pressure ramped to 16cm and practically blew the mask off my face) and am now at CFLEX 1, which is at least comfortable.

At 8.5cm, which has so far eliminated typical OA, I can probably deal with CFLEX at 0, I could give that a try tonight.

thanks again.


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#4
dottore, I have become so accustomed to answering Resmed questions I used the EPR without looking. We both have A-flex. I go back and forth on this, and for me the A-flex doesn't make much difference. I have tried from zero to three and tend to do better at lower settings.
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#5
I also have System One Auto - I fiddled around with Aflex settings and level of 1 was still not my favorite, but better than 2 or 3.

I finally dumped mine to 0 Aflex, but if you have this machine, you'll note you cannot set to 0 without shutting off pressure relief completely (which is auto-tritrating CPAP). That means my exhale pressure and my inhale pressure are the same.

I have done this for 42 nights now, and like the setting the best (of those I have tried).

I may try CFLEX of 1 to see if I like this.

I have low pressure settings, and rarely even go about 8.0 cmH2O.

Good luck.

QAL
Dedicated to QALity sleep.
You'll note I am listed as an Advisory Member. I am honored to be listed as such. See the fine print - Advisory Members as a group provide advice and suggestions to Apnea Board administrators and staff concerning Apnea Board operation and administrative policies. 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.
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#6
With the BiPAP I can set EPAP/IPAP separately as well as Biflex. Too many options. Smile
I get the best results with a mnimum EPAP of 11 and let the IPAP float 1 to 4 cm above that. Pressure charts end up looking pretty weird, but it has gotten me less than 1 AHI pretty routinely.

On the APAP, a A-flex of 1.0 worked best. I think this is all individual preference and just requires some experimentation.
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#7
(02-27-2015, 08:05 PM)quiescence at last Wrote: I also have System One Auto - I fiddled around with Aflex settings and level of 1 was still not my favorite, but better than 2 or 3.

I finally dumped mine to 0 Aflex, but if you have this machine, you'll note you cannot set to 0 without shutting off pressure relief completely (which is auto-tritrating CPAP). That means my exhale pressure and my inhale pressure are the same.

I have done this for 42 nights now, and like the setting the best (of those I have tried).

I may try CFLEX of 1 to see if I like this.

I have low pressure settings, and rarely even go about 8.0 cmH2O.

Good luck.

QAL
Like you I am at low pressure, 8.5, but 8 or even 7 may work, I haven't tried them yet. Tonight I'll try FLEX to none and just see what happens.

This whole exploration has been very interesting. Until 2 weeks ago I was using an M series CPAP set to 8.5cm. But I was experiencing these odd awakenings and thought my pressure might have been too low. So I set the pressure higher, 1cm per night, but there was no improvement in my sleep.

Wondering what the heck was going on, I went out and bought a PS1 on craigs list.

The first night I let it rip, min=7, max=20, AFLEX=3. Wow, was that ever a wild ride.

But to make a long story short, I'm back to the place I was with the series M. I set my PS1 to AUTO, but min=max=8.5.

Do I regret spending the $$ and time? no. Because now I know what the heck is going on. That's worth it. I also know a lot more about what a so called AUTO CPAP machine actually does.

many thanks to you and sleeprider for your help.


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#8
(02-27-2015, 05:50 PM)dottore Wrote: I'd like some opinions on what's going on in the attached plot.

From the limited amount of data, I don't think there's anything that meaningful in this graph, unless it happens a lot more often.

It looks like an "arousal," which means you woke up at least partially in terms of sleep phase. Your respiratory is often a little screwy before it settles down.

Probably something woke you up. In your graph, nothing much happens up to the big inhale and exhale. No indication it was an apnea that woke you up.

Then things are a little screwy until your respiratory system settles back into a more steady breathing pattern and O2 levels. Your SpO2 doesn't change enough to really matter. This is the kind of think you might see if you roll over, or hear a noise.

Zoom in and show about 1 minute before and one minute after the spike at 01:39:30.

It looks like you may have some flow limitations in general which may mean something. These will show up with square wave like flow waveforms instead of smooth sine curves.

That's a good screenshot, but let me suggest to not cut off the left panel with the AHI numbers.
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#9
(02-27-2015, 10:00 PM)archangle Wrote: Probably something woke you up. In your graph, nothing much happens up to the big inhale and exhale. No indication it was an apnea that woke you up.



That's a good screenshot, but let me suggest to not cut off the left panel with the AHI numbers.

As I said, the audio clearly shows I woke up, at least partially. There was no other noise in the room, so it wasn't something external to me. No indication of anything else, including possible square waves, etc. that could be flow limitations.

I cut off the AHI because it was meaningless since the number is made up of these kind of events. It's been running 1-2 each night.

I'm totally satisfied at this point that I have harmless central events going on. like many people on this board and as described in the referenced article (which says that as far as the researchers can determine it's harmless unless it really gets out of hand or you have heart disease).

thanks.
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#10
last night I did two experiments to test the theory that these central events have nothing to do with CPAP therapy. I was convinced yesterday, but it never hurts to test a theory.

First. At my usual bedtime, I went to sleep on the couch without my CPAP. I slept there for about an hour before switching to my bed and CPAP.

Though I didn't use the CPAP for that hour I did make an audio recording and used my pulse oximeter.

Twice during that hour the pulse oximeter showed the same pattern as in the chart I posted in the first post of this thread. And, as happened before, the audio recorded a sharp intake of breath just as the series of events started. And, though it was faint, I can hear that my breath varies after that sharp intake, increasing and decreasing in a periodic way before it settles down.

In other words, I had exactly the same arousal/breath/periodic breathing as I had with the CPAP.

Second. I wanted to prove that CO2 accumulation in the mask was not part of the problem (Again just testing my theory).

My mask has two ports on it. Not sure what those ports are used for, but you can connect tubing to them.

When I went to bed to use the CPAP, I opened the ports. This increased the mask leakage from 27 to 42. I left FLEX and pressure settings unchanged. If there was any accumulation of CO2, this would have reduced it.

surprise, surprise, I had central events just like the ones I had the nights before at approximately the same frequency.

so, if there was any doubt in anyone's mind (and I'm not saying there was), the two experiments showed that the CPAP has nothing to do with the central events.

To be fair, to prove that the CPAP has absolutely no effect on this I would have to do a lot more experiments, trying different pressures and FLEX settings. And because of the night to night variability, I would have to repeat the settings many times. I'd also have to recruit a couple hundred volunteers to try it. Which I'm obviously not gonna do.

So if someone is reading this and wanting to apply what I've said, I would encourage him/her to try various settings and see if there's an effect in his/her case.

This has been fun, ciao amici.

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