Minimum pressure

rkl122 wrote:So regarding the increase in events during REM, are you saying they were definitely not CA, or the algorithm at that time simply lumped CA's with obstructive events. More important, how does your current machine label the REM events? Any predominance of CA vs. obstructive? Any evidence that they are, or are not, post arousal?

I'm curious because for me the opposite occurs: no events during REM, and I'm trying to figure out why.

Back in 2009 when I was diagnosed and started cpap therapy we didn't have machines that flagged centrals separately.
We were never officially told what the machine might do with centrals in terms of where it might dump them. All we were told was that the machine in apap mode wouldn't respond to centrals with an increase in pressure so we sort of assumed any increased pressure was the result of obstructive apnea events of some sort.

Unofficially I got a chance to ask a Respironics software person what actually would the machine do if it spotted a central in terms of flagging and I was told it just got dumped into the hyponea/OA basket. That pretty much went along with what we saw on some reports where the person's AHI was high and increasing the pressure didn't help and the machine wouldn't automatically increase either.

No machine out there will label anything to do with REM sleep...about all I have ever done is look at the pattern of any events or pressure increases and the timing of the cycles and when I say "probable REM stage sleep events" I was going on past history (my own diagnostic sleep study) and the normal pattern of sleep cycles.
I didn't have an issue with centrals during my sleep studies...both the diagnostic and the titration from hell sleep study. Once I finally got a machine that flagged centrals...I still didn't have any centrals to speak of other than what might be a rare sleep onset central or some sleep/wake/junk centrals that aren't real anyway.
The machines or the software won't give us definitive markers for REM sleep...heck they can't even tell if we are for sure asleep or not because if they could we wouldn't be having sleep/wake/junk to sort through.

I read something not long ago (don't ask me where because I don't remember where and I didn't save it) where in REM sleep it is common for OSA events to worsen but centrals tend to reduce. I don't know how true that is nor was the mechanics of why the centrals were reduced explained. The mechanics of why Obstructive events worsen is pretty much common sense but if (big IF) centrals do reduce during REM those mechanics or why I don't understand.

So...the machines tell you nothing about REM sleep or sleep in general. Instead we are left to sort of use our own education and reasoning to come up with and idea when/if REM sleep is happening. It's not exact my any means but it's the best we have.

As to why you don't seem to have many events flagged during probable REM sleep....I would assume that you either didn't have very many or the pressure you are using is preventing them from happening.
Not everyone has it where their REM stage sleep is so much worse than non REM just like not everyone will have their OSA be hugely worse when they are on their back vs side sleeping. It's common but not necessarily something that happens with 100% of the sleep apnea population.

These machines weren't ever really designed to do much more than a general overview of the OSA therapy.
It us as users who often want to put the data we are given under the microscope and expect the machine to show us something or tell us definitively something that they simply can't do.

Thanks Pugsy for the response.

Pugsy wrote:..............

No machine out there will label anything to do with REM sleep...about all I have ever done is look at the pattern of any events or pressure increases and the timing of the cycles ..............
The machines or the software won't give us definitive markers for REM sleep...heck they can't even tell if we are for sure asleep or not because if they could we wouldn't be having sleep/wake/junk to sort through................So...the machines tell you nothing about REM sleep or sleep in general. Instead we are left to sort of use our own education and reasoning to come up with and idea when/if REM sleep is happening. It's not exact my any means but it's the best we have.

Agreed, and that's what I've done. Take a look at the respiration channel in the following capture:


Those bumps occur almost every night, at windows where I'm almost certain I was dreaming. And it's known that respiration rate increases during REM in some individuals. So I'm pretty sure they are REM stages. You can see how the flags absent themselves during those periods. This happens repeatedly, night after night.

..........As to why you don't seem to have many events flagged during probable REM sleep....I would assume that you either didn't have very many or the pressure you are using is preventing them from happening........

Obviously I don't have them, but why would the pressure selectively prevent them and not the surrounding ones? I have an alternate theory: that the great majority of events I do have are post arousal - ie. SWJ apneas, not sleep apneas. (This is supported by the patterns of the flow rate (upon zooming).) However, I've read that REM sleep is accompanied by a muscular paralysis. (Here's a ref: https://www.sciencedaily.com/releases/2 ... 131030.htm) If that's what's happening to me, it could explain why events which are basically muscular responses as opposed to true apneas, don't occur during REM. That's why I was curious to know if you'd decided whether your REM events are true sleep apneas, and if so, whether obstructive. (You've mentioned previously that you're not much into analyzing zoomed flow rates, so I understand this sort of analysis doesn't keep you up at night. )

I read something not long ago (don't ask me where because I don't remember where and I didn't save it) where in REM sleep it is common for OSA events to worsen but centrals tend to reduce. I don't know how true that is nor was the mechanics of why the centrals were reduced explained. The mechanics of why Obstructive events worsen is pretty much common sense but if (big IF) centrals do reduce during REM those mechanics or why I don't understand.

By "worsen" you mean "require more pressure to suppress" or "increase in frequency"? Either way, not obvious to me how the OA mechanics would be affected by REM (unless my theory above applies). What am I missing?

Thanks Pugsy, -Ron

rkl122 wrote:By "worsen" you mean "require more pressure to suppress" or "increase in frequency"?

For me...both.

rkl122 wrote:Those bumps occur almost every night, at windows where I'm almost certain I was dreaming. And it's known that respiration rate increases during REM in some individuals. So I'm pretty sure they are REM stages. You can see how the flags absent themselves during those periods. This happens repeatedly, night after night.

They do sort of conform to times where we would expect to see REM sleep stage happening.
Normal cycles start about 90 minutes after sleep onset and increase in frequency and duration as the night progresses with the greatest amount of REM sleep likely to happen during the wee hours of the morning.
That is of course assuming that the sleep cycles progress normally but they can be impacted by wake ups or arousals that mess with the cycles.

Did you know that you don't have to be in REM sleep to dream? Dreaming can actually happen during any sleep stage.
It isn't something that only happens during REM.

rkl122 wrote:but why would the pressure selectively prevent them and not the surrounding ones?

Who knows....and in reality why does it matter? Could be sleep position playing a part.
Are those flagged events "real" or SWJ? It wouldn't be impossible for some of them to be SWJ because it's also normal to waken briefly after REM stage sleep. Go look at all the normal hypnograms and you see a tiny brief awakening after REM. Most of us don't remember that awakening so we assume it doesn't happen but we can have a lot of awakenings that we don't remember.

rkl122 wrote:. That's why I was curious to know if you'd decided whether your REM events are true sleep apneas, and if so, whether obstructive.

Oh...my events were most definitely real apneas and definitely obstructive.
Per my sleep study....OSA with no centrals of any consequence...and the machine raises the pressure like crazy trying to kill the little buggers.
Or if it doesn't have the ability to raise the pressure then I get some ugly clustering.
See this thread as I have a couple of examples of some ugly clustering that happened because I was using fixed pressures.
viewtopic.php?f=1&t=88508&st=0&sk=t&sd= ... ster+child

rkl122 wrote:What am I missing?

I don't know because I am unclear as to what you are searching for.
Your posted report doesn't show the pressure graph and includes graphs that I personally don't utilize like the minute volume graph.
Are you trying to decided if what you are seeing (the events flagged) is real or not? I would suspect they are real since you say this is what you see night after night. We have no way to know 100% for sure though and for that reason we sometimes have to just try different stuff to see if it makes any difference in what we see or how we sleep or how we feel. Sometimes we just can't get a black and white answer from the data the machine provides.
From looking at your report...if it were my report I would want to try to "clean up the clutter" a little bit. It isn't a horrible looking report but there's just a little too much clutter present to suit me. Just a little bit of everything which might be impacting my sleep quality.
I assume you aren't feeling so great or you wouldn't be trying to put all this under the microscope and asking all these questions. So if it were me and I didn't feel so great....I would try a little more minimum pressure to see if the clutter would clean up a bit and if it did clean up then see if it helped how I felt during the day and maybe how I felt about sleep quality. I don't know that it would do anything but it's something to do and try to see if it helps or not.

I am more of a try to fix something by doing something girl than I am the sort to try to decide exactly what sleep stage I might be in or not. Since we can't get clear black and white answers from the machine I don't spend a lot of time looking for them. Instead I just prefer to try something and see if it helps or not.

So...I don't know what you are missing because I don't know what you are looking for or expecting.

Pugsy wrote:..............
Your posted report doesn't show the pressure graph and includes graphs that I personally don't utilize like the minute volume graph.
Are you trying to decided if what you are seeing (the events flagged) is real or not? ...........

That configuration was just to show the respiration and event channels. Yes, I've already decided - from lots of analysis of zoomed flow graphs, that almost all my events are SWJ apneas.

...I don't know what you are missing because I don't know what you are looking for or expecting.

I was responding to your statement:

The mechanics of why Obstructive events worsen [during REM] is pretty much common sense....

What I'm missing is the common sense, because I don't see why they should worsen.

I am more of a try to fix something by doing something girl than I am the sort to try to decide exactly what sleep stage I might be in or not.

I know. It'd save me some grief to be the same way.

I assume you aren't feeling so great or you wouldn't be trying to put all this under the microscope and asking all these questions. So if it were me and I didn't feel so great....I would try a little more minimum pressure to see if the clutter would clean up a bit and if it did clean up then see if it helped how I felt during the day and maybe how I felt about sleep quality. I don't know that it would do anything but it's something to do and try to see if it helps or not.

Yup, done. I've already achieved consistent AHI in the 2-3 range by raising pressure. (I had backed down to test some things for the night I show above.) Will raise even further.

Thx Pugsy, -Ron

rkl122 wrote:What I'm missing is the common sense, because I don't see why they should worsen.

From what I have read about why OSA worsens in REM is that the airway tissues relax even further so there's a greater chance of the tissues "relaxing" and blocking the airway even more than they do in other sleep stages.
Why does it do it for some people and not others? Beats me but it happens just like supine sleeping is horribly worse for one person and maybe not even change things one bit for another person.

The "why" isn't as important to me as "what can I do to fix it".

It seems like everything associated with sleep apnea and/or OSA or cpap therapy comes with a really big YMMV sticker.
The only thing consistent is there is no consistency.
If I can't change something I move on and don't bother expending energy (physical or mental) trying to sort through something that there simply may not be a clear black and white answer to and even if there was...would it change what I was doing anyway? If it isn't going to change something I am doing then why worry about it...at least that's my approach to all this.

Works for me...may not work for someone else and that's fine too....that's another YMMV sticker thing.

This has all come about from over 7 years on the machine....way back when I first started therapy I put everything under the microscope and we didn't have as big of a microscope back then. Guess it's a good thing it was limited or I might have made myself crazy trying to answer every little "what if" when there wasn't an answer available.
So I do understand people wanting to do the microscope thing....and if that's what they want to do then I certainly am in no position to tell them "don't do it"...I just don't want to participate. Been there and done that and prefer now to concentrate my energy in other areas where I can see more definitive results.

I go months without pulling the SD card and I never look on the machine for last night's data.
But I do remember when pulling the card was the very first thing I did when I got up and reviewing last night's data was the first thing I did with my first cup of morning coffee.


Doesn't mean I won't try to help those wanting to use the microscope when I have time and can. I just don't want to do the microscope thing myself so I don't do it unless it is something really urgent.

Great answers and explanations, Everyone. I am going to reread this thread many times. I certainly understand things much better than I did before. As to what I am going to do, I need to digest this info for awhile before making any changes. Thanks especially to Pugsy.

I may have more comments and questions once I have thought more about all this.