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Your AHI 12.9 was Horrible; See a doctor.
#11
I think Tyshoes really means that he suspects many of the CAs he/she does see on the record are not really CAs.
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#12
(02-22-2015, 08:30 PM)TyroneShoes Wrote: I had less than 1% centrals in my un-PAPed home test, but have had a 2:1 central ratio ever since starting xPAP.

The centrals are apparently not coming from me, then. I am skeptical of centrals being false positives in many cases, especially when I am awake and get centrals flagged that can't possibly really be CA events.

Well, if you want to say that, you can't have obstructive apneas or hypopneas when you're awake.

Other than not knowing if you're awake or not, I think when the machine says "central," it probably is a central. Look at it and see how long and how completely you stop breathing.

Also realize a central isn't necessarily more harmful than an obstructive. The number and severity is what counts.

Get the free SleepyHead software here.
Useful links.
Click here for information on the main alternative to CPAP.
If it's midnight and a DME tells you it's dark outside, go and check it yourself.
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#13
(02-22-2015, 08:30 PM)TyroneShoes Wrote:
(02-22-2015, 12:25 AM)TheManseHen Wrote: ...Still higher in the Centrals dept. nearly 2;1 ratio in favor of centrals...

I had less than 1% centrals in my un-PAPed home test, but have had a 2:1 central ratio ever since starting xPAP.

The centrals are apparently not coming from me, then. I am skeptical of centrals being false positives in many cases, especially when I am awake and get centrals flagged that can't possibly really be CA events.

That makes sense to me. CPAP machines are great at coping with obstructive apnea. I don't have CA issues and my AHI went from 43 at the sleep center down to zero many nights and rarely above 1.0. Once you get rid of most of the obstructive events, what's left are the central events. There could very well be two different root causes to those two classes of events.
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#14
(02-22-2015, 03:38 AM)OpalRose Wrote:
(02-22-2015, 12:25 AM)TheManseHen Wrote: Thanks Geoff (pretty sunset and boat pic!) and Sleeprider. Will work on the graph changes and posting some. Meanwhile, I had a great night last night after the four horrible ones. AHI 3.9 Still higher in the Centrals dept. nearly 2;1 ratio in favor of centrals. BUT I slept very deeply and well and woke refreshed which was lovely after so many bad days both numerically and feeling wise.

I personally find it easier to use ResScan to look at the horizontal detail on graphs, setting it to the various degrees of blow up. (ie 2 hours 30 seconds etc) but I like Sleepyhead for other reasons. I end up checking both daily. Sleepyheads photo taking feature is wonderful. I'll see if I can get a graph or two on here or on the next "woe is me" post I make (-:

Thanks so much for your helpful info. I'm still learning.

The Manse Hen


Hi Manse Hen,
Great AHI numbers! Keep tabs on those Centrals, hopefully they will start to come down too. Are you over your Flu Bug? Bed
OpalRose

Thanks for asking Opal, Yes, I'm all better. Whatever I thought I was coming down with, passed me by.

The Hen
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#15
(02-22-2015, 11:25 PM)archangle Wrote:
(02-22-2015, 08:30 PM)TyroneShoes Wrote: I had less than 1% centrals in my un-PAPed home test, but have had a 2:1 central ratio ever since starting xPAP.

The centrals are apparently not coming from me, then. I am skeptical of centrals being false positives in many cases, especially when I am awake and get centrals flagged that can't possibly really be CA events.

Well, if you want to say that, you can't have obstructive apneas or hypopneas when you're awake.

Other than not knowing if you're awake or not, I think when the machine says "central," it probably is a central...

It might be a central. But it might not. What I am thinking here is that the algorithm for detecting and flagging a central may not be all that perfect, and flagging any of these events is always a matter of degree. I can easily fool the machine into flagging a central by simply holding my breath, or flagging a hypop by breathing shallowly. What if I have a dream where I am holding my breath? Do I really hold my breath? Does that get flagged? Since I am doing it on purpose, is it actually a central event, even though I am asleep? Lots of grey area.

The xPAP does not determine whether you have events or not, it flags what it thinks might be events based on clues only loosely connected in an objective manner to the subjective events, and that implies a component of error, and especially so if it isn't even smart enough to determine if you are asleep or not, this being a machine specifically designed to treat, prevent, and flag events that happen during sleep.

Otherwise, how do we explain how an untreated person who suffers from severe OSA who has virtually no centrals, then automatically has twice as many centrals as obstructives every night once under treatment with a lowered AHI? This is not a rhetorical question; I would really like to know the real answer to that.

So when someone tells me "pay no attention to that man behind the curtain", it motivates me to want to tear that curtain down off the hooks.

AHI is a simplified look at things anyway. An "AHI of 5" is not a clear indicator of the nuts and bolts of what is going on; it is more like a summary alarm, which is why I think it is folly for a computer program to make a snap judgement on sparse info enough to have the arrogance to tell you to "see your doctor".

AHI was created so that you can get a snapshot; a glimpse at the surface of what is going on, because we need that and it is not always practical to parse everything to the nth degree every morning. It has a purpose, and that is it. But a PS test couldn't give a rat's hat about AHI, because it is too busy being deeply involved with the extended data deep below that surface that AHI only is a glimpse of.

Would you rather have 4 centrals that were each 45 seconds long? Or 12 centrals that were each 15 seconds long? You are in apnea for the same total time, but the machine scores a CI for 4 events as a 4 and a CI for 12 events as a 12, even though your 02 desat was probably more significant for the 4 events, meaning those longer ones were essentially more destructive. In that case, is a CI of 4 better than a CI of 12? It does not seem so. Yet the CI is a major part of the imperfect data that informs AHI, making AHI less than perfect, by definition.

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#16
yep. I like SleepyHead giving my a total time in apnea and like SPO2 Assistant telling me total time under 88%. That tells me something more about how serious each of the events end up being.
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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#17
Is 88% the line for the "danger zone"?
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#18
(02-22-2015, 08:30 PM)TyroneShoes Wrote:
(02-22-2015, 12:25 AM)TheManseHen Wrote: ...Still higher in the Centrals dept. nearly 2;1 ratio in favor of centrals...

I had less than 1% centrals in my un-PAPed home test, but have had a 2:1 central ratio ever since starting xPAP.

The centrals are apparently not coming from me, then. I am skeptical of centrals being false positives in many cases, especially when I am awake and get centrals flagged that can't possibly really be CA events.

First, the machine and the software are not flagging Central Apneas. They are flagging apneas that occur with a clear (unobstructed) airway.

Second, you would be surprised how many times you stop breathing momentarily when you are awake. The machine knows that it is running so it assumes that you are asleep.

If you want to know if the machine is scoring false positive CAs, look at the flow data. You will be able to see for yourself. I haven't seen a false positive yet.

One may have more CAs when starting therapy because the body is acclimating to sleeping with a stranger in the bed (CPAP). The body is not used to getting oxygen so easily and decides that it is topped off so it stops breathing for a little bit to let the CO2 level come back up a little.

Best Regards,

PaytonA
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#19
(02-23-2015, 04:08 PM)TyroneShoes Wrote: It might be a central. But it might not. What I am thinking here is that the algorithm for detecting and flagging a central may not be all that perfect, and flagging any of these events is always a matter of degree. I can easily fool the machine into flagging a central by simply holding my breath, or flagging a hypop by breathing shallowly. What if I have a dream where I am holding my breath? Do I really hold my breath? Does that get flagged? Since I am doing it on purpose, is it actually a central event, even though I am asleep? Lots of grey area.

You're only fooling it because you're awake, which we know the machine can't tell.

If you hold your breath, that's an apnea, except for the condition of you needing to be asleep before you count it.

True hypopneas require you to both be awake and to have an SpO2 drop at the same time as the event. CPAP machines miss out on some hypopneas because they can't verify the SpO2 drop.

(02-23-2015, 04:08 PM)TyroneShoes Wrote: Otherwise, how do we explain how an untreated person who suffers from severe OSA who has virtually no centrals, then automatically has twice as many centrals as obstructives every night once under treatment with a lowered AHI? This is not a rhetorical question; I would really like to know the real answer to that.

Are you talking about pressure induced central apnea? That's pretty well understood. CPAP pressure can cause your tidal volume and minute ventilation to increase. The increased minute vent can cause "washout" of CO2. Your respiratory drive is mostly based on your CO2 levels, not oxygen. Low CO2 makes some people stop breathing for a while until your CO2 picks back up and your respiratory drive makes you start breathing again. Another theory is that your lungs become more inflated and the stretch receptors in your lungs gives feedback that reduces your respiratory drive.

Google "Pressure Induced Central Apnea" and you'll find a lot of info.
Get the free SleepyHead software here.
Useful links.
Click here for information on the main alternative to CPAP.
If it's midnight and a DME tells you it's dark outside, go and check it yourself.
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#20
(02-23-2015, 08:48 PM)TyroneShoes Wrote: Is 88% the line for the "danger zone"?

That was the default alarm setting on my oximeter, and I had also read that under 88 was cell damage territory.

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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