Can central apneas be caused by too-high pressure?

[ellen1159]

Is it possible that I'm having CA's due to the pressure setting on my BiPap machine being too high? My pressures are set at 15 and 24, I noticed in my Encore basic stats from the past two nights that I go between 15.1 and 19.1 pressure. During my sleep study I had only one CA during the dx phase but 14 during the titration phase.

I don't think I have brain injury and my last cardio stress test was good.

[khauser]

In susceptible people it is possible for the pressure to raise to a point that causes central apneas, yes ... BUT:
1) Remember that your machine can not detect central apneas. It can only probe and show that it thinks the airway was NOT obstructed during the apnea.
2) MANY people see CAs during time that they are (at least partially) awake, maybe because we are more active.

Also, the usual treatment option for this problem is to use a BiPap machine, which you already have. But I will have to defer to someone with more experience on how to accommodate this issue with the BiPap.

If BiPap doesn't work, ASV is the next option. But make sure you exhaust all BiPap options first as some people have a greater degree of difficulty adjusting to the ASV.

[joshelmintz]

How long has it been since you were titrated? May need to go again. I just went through the same thing you are. I was on a bipap machine that did not register nor treat centrals. To answer your question, from what I have been told is yes high pressures can cause centrals to appear. Too low of pressure can do the same. My suggestion would be to speak with the doc. Are you still tired after therapy? If so you need either a bipap machine that has a backup rate to treat centrals or an asv. I'm using a bipap st to see how it does for my centrals and if no improvement I'm going to get an asv. If your having no side effects like continuing daytime fatigue the centrals may go away by themselves especially if your new to this. If this is an ongoing problem get to the doc for a new study. I was diagnosed two years ago with obstructive apnea and am now diagnosed with complex.

[Pugsy]

Until you are able to sleep longer and without the large leaks and fiddling with your mask I wouldn't worry too much about the possibility of centrals being caused by pressures.
Your report from last night wasn't nearly as ugly as the night before in terms of CAs. It was still a bit ugly in a couple of spots but those clusters also coincided closely with some large leaks and there's a good chance that you were awake or semi awake during those clusters and if that was the case then they don't count.

Right now just concentrate on getting the leak issues under better control and sleeping longer without sleep interruptions...then we can worry about if those CAs mean anything exciting or not.

[ellen1159]

Until you are able to sleep longer and without the large leaks and fiddling with your mask I wouldn't worry too much about the possibility of centrals being caused by pressures.
Your report from last night wasn't nearly as ugly as the night before in terms of CAs. It was still a bit ugly in a couple of spots but those clusters also coincided closely with some large leaks and there's a good chance that you were awake or semi awake during those clusters and if that was the case then they don't count.

Right now just concentrate on getting the leak issues under better control and sleeping longer without sleep interruptions...then we can worry about if those CAs mean anything exciting or not.

I was awake a lot last night, fooling with the straps.

[ellen1159]

How long has it been since you were titrated? May need to go again. I just went through the same thing you are. I was on a bipap machine that did not register nor treat centrals. To answer your question, from what I have been told is yes high pressures can cause centrals to appear. Too low of pressure can do the same. My suggestion would be to speak with the doc. Are you still tired after therapy? If so you need either a bipap machine that has a backup rate to treat centrals or an asv. I'm using a bipap st to see how it does for my centrals and if no improvement I'm going to get an asv. If your having no side effects like continuing daytime fatigue the centrals may go away by themselves especially if your new to this. If this is an ongoing problem get to the doc for a new study. I was diagnosed two years ago with obstructive apnea and am now diagnosed with complex.

I'm a newbie at this, just had my study done in April, have had machine three and half months and last night was the first time I went 8 hours with the mask on. I also was awake a lot and fiddling with the straps because of the leaks I was having. I think I need more time. Seeing sleepdoc in two weeks but I may go earlier to get help with mask fitting.

[STL Mark]

You may find this thread from 2011 of interest. It discusses the same issue.

[sawinglogz]

Right now just concentrate on getting the leak issues under better control and sleeping longer without sleep interruptions...then we can worry about if those CAs mean anything exciting or not.

This is right. As someone who does have pressure-induced CAs, I can tell you that the machine's not going to detect them accurately if you're awake or you're fighting with large leaks.

It'll generally flag them properly if you're actually asleep (not just falling asleep or awakening: "transitional" central apneas are normal) and the mask has a good seal.

And even then they don't usually worry unless you're above 5/hr while truly asleep.

It doesn't hurt to keep an eye on them now, but don't worry about them until at least the leaks are resolved.

To answer your specific question, though, my percentage of patient-initiated breaths drops like a rock any time the pressure increases on my ASV. It'll be cranking along at 98% (2% machine-triggered) and then it will boost pressure to avoid a hypopnea, and then it'll have to trigger 50-75% of my breaths for the next 5 minutes. So for me, at least, pressure increases due induce central apneas.

[khauser]

Hi Ellen,
I discovered after my answer to you that you have a number of open threads about different issues. Chances are very high that there is a bunch of correlation between them, so you're actually likely to make things harder by isolating them in different threads of discussion.

Pugsy is spot on that until the leaks are under control, pretty much all of the other numbers are meaningless. For instance, how does the machine detect a clear airway apnea from an obstructed apnea? An apnea means the machine is not detecting breathing. To determine if it is a CA or OA, the machine sends pulses of air (brief increases in pressure) and can determine whether you have an obstruction or not based on what happens with the pulse ... UNLESS you have a large leak. Because if you have a large leak, the pulse goes with the leak, NOT in to your nose where it was meant to. The leak makes the machine think no obstruction exists, so its a clear airway obstruction as far as it can determine.

So please take Pugsy's advice and deal with the leaks before even worrying about anything else.

[BlackSpinner]

I get arts related newsletters. The one this morning said "look at the road ahead where you are going, not down where your wheels are" they were comparing mountain biking with an arts career. I am suggesting that you focus just for a while on your goal of wearing your cpap machine and sleeping with it.

Sort of like when you are driving you look ahead to where you are going, most beginners when trying to go around the corner, look at the corner and over compensate.

[ellen1159]

You're right, I am so frickin' obsessed with all the problems I"ve been having getting adjusted to my machine, and the length of time it has taken me to get this far, that I'm worried about stuff that may not even be happening.

Going to try the Pad a cheek liner tonight and hope I made the hole big enough to breathe comfortably but not so big that it defeats the purpose.

Thanks, everyone, for your feedback and support.

[Denial Dave]

when trimming the pad-a-cheek liner, only trim a little off at a time.

I then test fit it on my mask for size to decide if it is cut open enough for me.

I've been on bi-pap at 20 / 14.4 for a year now.... no sign of any increase or change in centrals....

I get the typical sleep/wake/junk centrals reported on sleepyhead about 30 minutes before my alarm clock goes off.

[archangle]

Is it possible that I'm having CA's due to the pressure setting on my BiPap machine being too high? My pressures are set at 15 and 24, I noticed in my Encore basic stats from the past two nights that I go between 15.1 and 19.1 pressure. During my sleep study I had only one CA during the dx phase but 14 during the titration phase.

I don't think I have brain injury and my last cardio stress test was good.

First off, why are you worried? Are you having problems?

Ellen, do your Encore results show CAs? How many? What's your total AHI?

BTW, download SleepyHead. It's easier to view the data. It's especially easier to look and see how long the apnea lasts. A 12 second apnea is not nearly as bad as a 120 second apnea.

You don't have to have brain injury to have central apnea. You especially don't have to have a brain injury to have pressure induced centrals.

Also, realize that CA isn't necessarily any more harmful that OA. They're just harder to elimnate.

In susceptible people it is possible for the pressure to raise to a point that causes central apneas, yes ... BUT:
1) Remember that your machine can not detect central apneas. It can only probe and show that it thinks the airway was NOT obstructed during the apnea.
2) MANY people see CAs during time that they are (at least partially) awake, maybe because we are more active.

Also, the usual treatment option for this problem is to use a BiPap machine, which you already have. But I will have to defer to someone with more experience on how to accommodate this issue with the BiPap.

If BiPap doesn't work, ASV is the next option. But make sure you exhaust all BiPap options first as some people have a greater degree of difficulty adjusting to the ASV.

If you're asleep and the S9 or PRS1 says it's a central apnea or "clear airway" apnea, it's almost certainly a central apnea. The main risk is that it may classify a central apnea as obstructive.