Question about CPAP-induced Centrals

[rd1978]

This question is directed to JohnB and Pugsy (and any others who may be able to offer advice). . .

After more than 6 weeks of experiencing severe amounts of Centrals (avg. 35/hr!) on my S9 Autoset (FYI, I never had any Centrals during sleep study; so it has been documented that they are CPAP-induced), I finally had my ASV titration last night. I won't know the results for a few days, and the tech, obviously, wasn't allowed to share any of the data with me this morning. But he did confirm that Centrals, when they do occur while on CPAP, tend to occur at higher pressures.

While I am waiting for the results and, ultimately, a new machine with ASV capability, I'd like to experiment with my S9 Autoset to see if I can get the Centrals down. So, my question is this: is there a pressure below which Centrals are less likely to be triggered? Right now my setting are 8-12, and my Obstructives and snoring are well-controlled.

Thanks in advance for your advice!

[Pugsy]

There used to be the thought that centrals weren't as likely to happen until pressures got to 10 cm but I have seen then pop up with as little as 6 or 7 cm pressure. They happen not just with "higher" pressures...they can happen with just a little bit of pressure.
If I remember your reports correctly even with your 8 to 12 range you rarely got above 9 or 10 cm though. Plus you were using EPR so part of the time you were using less than that during exhale.

While waiting for your follow up you could maybe try straight cpap mode with a lower starting pressure and see how much the central count decreases without hopefully causing the OA and hyponea count to go sky high.

In your case I would maybe try 6 cm straight cpap and see what happens.

[rd1978]

There used to be the thought that centrals weren't as likely to happen until pressures got to 10 cm but I have seen then pop up with as little as 6 or 7 cm pressure. They happen not just with "higher" pressures...they can happen with just a little bit of pressure.
If I remember your reports correctly even with your 8 to 12 range you rarely got above 9 or 10 cm though. Plus you were using EPR so part of the time you were using less than that during exhale.

While waiting for your follow up you could maybe try straight cpap mode with a lower starting pressure and see how much the central count decreases without hopefully causing the OA and hyponea count to go sky high.

In your case I would maybe try 6 cm straight cpap and see what happens.

Thanks Pugsy! I was thinking the same thing. Perhaps I'll start at 9cm, and then lower it by 1cm each day and see what happens.

[Pugsy]

I would go the other way if it were me...start lower and work my way up...but you can do what you want.
I don't think doing 9 cm is going to show you much of anything at all...that's real close to where your machine wanted to spend more of the night anyway and you had a truckload of centrals in that 9 to 10 range.
I would start at 7 just to see if the centrals reduced at all.

[rd1978]

I would go the other way if it were me...start lower and work my way up...but you can do what you want.
I don't think doing 9 cm is going to show you much of anything at all...that's real close to where your machine wanted to spend more of the night anyway and you had a truckload of centrals in that 9 to 10 range.
I would start at 7 just to see if the centrals reduced at all.

Makes sense. I'll follow your advice.

[jnk]

. . . straight cpap mode with a lower starting pressure . . .

And maybe without EPR?

Some may consider ResMed's version of EPR to be virtually a form of bilevel, which could, for some on the edge anyway, induce centrals, in theory.

[JohnBFisher]

I'ld also like to confirm that someone with CPAP induced central apneas should consider straight CPAP and not an Auto CPAP setting. The Auto CPAP (or BiPAP) tends to induce centrals as the pressure changes.

[Pugsy]

And maybe without EPR?

Some may consider ResMed's version of EPR to be virtually a form of bilevel, which could, for some on the edge anyway, induce centrals, in theory.

You know I thought about that....but waffled a bit and then set it aside thinking just change to cpap first and then see what happens.
If I remember right he was only using 1 or 2 EPR anyway. I was thinking let's only change the pressure and not the breathing rhythm at this point to lessen the change in the routine so a not as likely to cause sleep disturbance due to the change. Maybe revisit the EPR thing if 7 cm didn't help at all.
Bilevel pressures being the actual trigger for centrals is a very tiny chance from what I have read. If it was all that prevalent I would think we would see a lot more of it with all the EPR being used and the bilevel machines being used. We just don't see it much at all and in fact I don't think I have ever seen it on this forum.
I read the studies and I know it can happen but I don't think it is very common at all.

So that's why I waffled a bit...decide to suggest just the one change right now...straight cpap mode at a lower pressure to see what happens. If we make two changes...and get a positive result we don't know which change helped.

[jnk]

I'ld also like to confirm that someone with CPAP induced central apneas should consider straight CPAP and not an Auto CPAP setting. The Auto CPAP (or BiPAP) tends to induce centrals as the pressure changes.

And I agree that what John and Pugsy are saying is based on documented observation and standard practice, whereas my statement on ResMed's EPR is, as far as I know, only something in the realm of theory as a possibility.

[JohnBFisher]

... decided to suggest just the one change right now...straight cpap mode at a lower pressure to see what happens. If we make two changes...and get a positive result we don't know which change helped. ...

Now, where's the fun in that?

It's far more likely we'ld really screw things up for the OP by changing two or more things at once.

We've seen EPR trigger sleep problems (hypopneas / apneas), but not as frequently has it been shown to trigger central apneas.

[avi123]

I think that I am reading John's post as follows:

There might be some problems with your experimentations.

1) Any Central Apnea event (CAI) that you'll see in the output data from your S9 would be questionable if it was a real CAI or pressure induced CAI. To verify it you need a chest and abdomen sensors and an EEG tester.

2) Pressure induced CAIs are likely to resolve over time while real CAIs are not. There are certain underlying medical conditions causing these to happen.
If you're one of those who have CompSAS (Complex Sleep Apnea Syndrome), then the use of an APAP machine would be contraindicated, i.e. it could cause further damage.

3) To come up with the suitable Machine and correct Therapeutic Pressures set- up you need to undergo a sleep study.

[rd1978]

I think that I am reading John's post as follows:

There might be some problems with your experimentations.

1) Any Central Apnea event (CAI) that you'll see in the output data from your S9 would be questionable if it was a real CAI or pressure induced CAI. To verify it you need a chest and abdomen sensors and an EEG tester.

2) Pressure induced CAIs are likely to resolve over time while real CAIs are not. There are certain underlying medical conditions causing these to happen.
If you're one of those who have CompSAS (Complex Sleep Apnea Syndrome), then the use of an APAP machine would be contraindicated, i.e. it could cause further damage.

3) To come up with the suitable Machine and correct Therapeutic Pressures set- up you need to undergo a sleep study.

Avi,

As a matter of fact, I did undergo a sleep study last night. It was an ASV titration. The results, however, won't be in for a few days. I'm using the time between now and then to experiment a little with my settings to see if I can make the Centrals go away (or at least diminish in number). Given that I had no Centrals at all until after starting PAP therapy, and have absolutely none of the medical conditions that can cause Centrals, there's virtually no doubt that they are PAP-induced . In all likelihood, I'm one of the small percentage of folks who have Complex Sleep Apnea, in which case the correct treatment will be a machine with ASV capabilities. But, again, since I have a few days to play around, it's worth experimenting to see if perhaps my Centrals might only occur above a certain pressure.

If setting my S9 Autoset in CPAP mode with a relatively low pressure (i.e. 6cm or 7cm) can give me a low AHI with no Centrals, that would be great. The question is, should I use the EPR or not? Frankly, since I would have no trouble at all exhaling against such a low pressure, I'm inclined to turn the EPR off.

[jnk]

. . . since I would have no trouble at all exhaling against such a low pressure, I'm inclined to turn the EPR off.

Pugsy makes an excellent point about not changing more than one thing at a time when trying to figure things out in the midst of treatment.

Don't be thrown off-track by the likes of me and avi.

[Pugsy]

Using EPR also effectively reduces the overall pressure that is delivered due to the reduction in pressure during exhale.
So on one hand it might (stress might) allow of a little reduction which might allow for the pressure reduction (even slight) to maybe not trigger the centrals...it's a big maybe.
Also there is the maybe that bilevel pressures trigger centrals and yes using EPR makes the machine work essentially like a bilevel machine works.
So there are maybes on both sides of the equation.

The reason I suggest not changing EPR along with the reduction in pressure to maybe 6 or 7 in cpap mode is because that change itself could affect the overall quality of sleep. When a person has been used to one way of doing things for a while the body gets accustomed to it and sometimes the brain wants to rebel when it doesn't sense that things are pretty much the same.
So it isn't so much because a person could easily do 6 or 7 cm cpap mode and don't really need EPR...it's because the brain is used to EPR and the brain likes for things to be predictable. It's possible that eliminating EPR might change the predictability of the respiration rhythm that the brain has become accustomed to. Change it and sleep quality might be changed...more wake ups maybe...and with more wake ups then there's the chance of more centrals getting flagged because of awake events or sleep onset events messing up the scoring.

Now it may not make any difference to the brain...but it might.
What I would do is leave EPR alone...try cpap at 6 or 7 cm...see if any of the event numbers change in any category...if centrals reduce then we have a positive outcome...if obstructives increase we can then turn EPR off and see if the slight increase in overall pressure helps with the obstructives...
If nothing changes with the reduction to cpap mode...then try turning EPR off.
If centrals reduce but not much and obstructives stay the same...then try turning EPR off to see if it is bilevel that is maybe a factor.

Lots of ways to go about experimenting. I do like to keep the variables to a minimum whenever possible as I think it makes for a better controlled experiment. Since there is a remote chance that turning EPR off could mess with sleep quality then if it were me I would leave that change out of the mix as long as possible.....but that's just me.
I have personally experienced what happens when a change in breathing rhythm occurs when turning off the exhale feature after using it for a while. There was significant sleep disturbance and a generally horrible night's sleep and that's all I changed.

I am not saying don't experiment with turning EPR off...just suggesting that maybe it be done later instead of tonight.
If you reduce the pressure and used cpap mode and turn off EPR and you have a horrible night's sleep tonight...who/what are you going to blame it on?

[rd1978]

Using EPR also effectively reduces the overall pressure that is delivered due to the reduction in pressure during exhale.
So on one hand it might (stress might) allow of a little reduction which might allow for the pressure reduction (even slight) to maybe not trigger the centrals...it's a big maybe.
Also there is the maybe that bilevel pressures trigger centrals and yes using EPR makes the machine work essentially like a bilevel machine works.
So there are maybes on both sides of the equation.

The reason I suggest not changing EPR along with the reduction in pressure to maybe 6 or 7 in cpap mode is because that change itself could affect the overall quality of sleep. When a person has been used to one way of doing things for a while the body gets accustomed to it and sometimes the brain wants to rebel when it doesn't sense that things are pretty much the same.
So it isn't so much because a person could easily do 6 or 7 cm cpap mode and don't really need EPR...it's because the brain is used to EPR and the brain likes for things to be predictable. It's possible that eliminating EPR might change the predictability of the respiration rhythm that the brain has become accustomed to. Change it and sleep quality might be changed...more wake ups maybe...and with more wake ups then there's the chance of more centrals getting flagged because of awake events or sleep onset events messing up the scoring.

Now it may not make any difference to the brain...but it might.
What I would do is leave EPR alone...try cpap at 6 or 7 cm...see if any of the event numbers change in any category...if centrals reduce then we have a positive outcome...if obstructives increase we can then turn EPR off and see if the slight increase in overall pressure helps with the obstructives...
If nothing changes with the reduction to cpap mode...then try turning EPR off.
If centrals reduce but not much and obstructives stay the same...then try turning EPR off to see if it is bilevel that is maybe a factor.

Lots of ways to go about experimenting. I do like to keep the variables to a minimum whenever possible as I think it makes for a better controlled experiment. Since there is a remote chance that turning EPR off could mess with sleep quality then if it were me I would leave that change out of the mix as long as possible.....but that's just me.
I have personally experienced what happens when a change in breathing rhythm occurs when turning off the exhale feature after using it for a while. There was significant sleep disturbance and a generally horrible night's sleep and that's all I changed.

I am not saying don't experiment with turning EPR off...just suggesting that maybe it be done later instead of tonight.
If you reduce the pressure and used cpap mode and turn off EPR and you have a horrible night's sleep tonight...who/what are you going to blame it on?

Thanks Pugsy. As usual, you make perfect sense.