EPR setting and effect on central apnea

[Canmore]

Judging from what I have read on Apnea Board and elsewhere, not using EPR is good for reducing both obstructive apnea and central apnea. My apnea is mostly central.

The reason for reduction in OA seems obvious -- keep the pressure on! -- and going from EPR 3 to 2 to 1 to none seems to be reducing my CA as well.

But why? If CPAP therapy tends to create CA events and biPAP therapy limits them, why would EPR, which to some extent mimics biPap (I think), reduce CA?

There must be something I'm failing to grasp here. Anyone able to help me with this?

[justMongo]

EPR lowers exhale pressure; permitting more CO₂ to expel. CO₂ washout tends to lower central ventilation drive in the brain.

So, EPR is a double edge sword. It may make it easier to breath out; but, for some people, it may induce CA.

[OpalRose]

When you say your apnea is mostly central, are they high enough to warrant a different type machine? Bipap doesn't treat CA's. You may need an ASV machine.

[GPSMapNut]

EPR lowers exhale pressure; permitting more CO₂ to expel. CO₂ washout tends to lower central ventilation drive in the brain.
So, EPR is a double edge sword. It may make it easier to breath out; but, for some people, it may induce CA.

Excellent point and well worth publicizing!
You made me realize why my CAs dropped when I changed from Flex 3 to 2 and than to 1.

[Sleeprider]

Just Mongo's explanation of why some people are sensitive to EPR or bilvel, is accurate. Not everyone experiences central apneas as a result of pressure differential, so YMMV.

EPR is a comfort setting, however the way it is implemented by Resmed, it is much more like bilevel, than the pressure reduction employed by Respironics. For OSA patients using relatively low CPAP pressure, a pressure reduction of 3 may not be a good idea, even though you can do it. For someone with a CPAP pressure of 7, the exhale pressure becomes 4. This can allow collapse of the airway, and CPAP pressure cannot open a collapsed airway, it can only act to prevent the obstruction.

When someone is titrated for a bilevel device, the EPAP is set to prevent OA (airway collapse), the pressure support is added to minimize hypopnea and RERA. A CPAP user is rarely aware of this, and may use EPR at a level that undermines the CPAP pressure efficacy. Now, if you understand how it works, it's fine to use any EPR setting, but it may require higher minimum CPAP pressure to use the maximum level of EPR. There is nothing wrong with that, but it surprises me that the manufacturer has made this a comfort setting available to patients. If you already know enough to set your own pressures, then you should be able to figure out how to use EPR without adverse affects.

[Canmore]

Thanks for those responses, especially justMongo's. If I interpret him correctly, he's saying that EPR helps to offload carbon dioxide that would otherwise be telling my brain to tell my lungs to take a breath.

That makes sense! Working my way down to no EPR may have been the main factor in reducing my CA to 10-20 events per night from the 60 or more I was having with EPR of 3 and other adjustments unchanged.

Further, my OA events have come down, too. Last night I had none.

OpalRose suggested that I may be better off with ASV. Possibly, but I'm a periodic breather, even in the daytime -- might have something to so with a lifetime of climbing mountains -- and probably nothing is going to cure me of that.

Nor does it seem to be much in need of curing. My initial sleep test showed a lot of apnea, type undetermined, but not much drop in oxygen concentration. Pre-CPAP, I never felt lousy in the morning or suffered much daytime sleepiness.

I got on CPAP mainly to quit snoring, which is to say on my wife's orders. The machine has also reduced my AHI numbers from 18-19 at the start to 3-6 now, which is good, of course, for my health generally.

Two things are keeping me on CPAP instead of going to ASV. One is the cost. Canada's otherwise great universal medical insurance doesn't pay for treatment of sleep apnea here in Alberta. And the other reason is that I have heart disease (bad family genetics; choose your parents wisely), and I have read that ASV is contraindicated in cases of congestive heart failure. My illness hasn't progressed to that, but I'm leery anyhow.

[OpalRose]

Canmore,
You seem to be doing well and you are right, an ASV may not be a good choice if you have heart disease, although that seems to be controversial, but why take chances.

I got a chuckle out of your comment "choose your parents wisely",
I inherited many possible diseases from my mothers side, which I am doing my best to avoid. My brother and sister take after my dad, who smoked all his life, ate whatever he liked, and lived to be 96.


Take care,

[Canmore]

Life ain't fair, eh? But it's sure better now that I'm on the tube. And if I weren't, life would still be better the alternative. Which I'm not tempting . . .

[Sleeprider]

I'm going to disagree with the concerns expressed here regarding the use of ASV in conjunction with general heart disease, and perhaps even for the specific cohort that was indicated as having a 2.5% increase in mortality risk with ASV. That Cohort was specifically individuals with congestive heart failure with left ventricle ejection efficiency less than 45%. If you have A-fib or have had bypass or other heart conditions, this is NOT your concern. Even the cohort found to be at higher risk by the Resmed study was an unexpected result, and one that is being challenged in newer studies, because the resmed study used outdated older machines, and considered individuals "treated" with 3-hours or more of use each night. Hell, CHF patients have a high probability of being deceased within 5-years of diagnosis regardless of ASV or PAP therapy.

Don't let this potentially erroneous study keep you from getting treatment that can improve your health and prevent advancement of heart disease, especially when it doesn't even apply to your condition. ASV provides the PAP therapy to resolve your OSA, and breath by breath pressure to resolve periodic breathing and centrals.

[Canmore]

I'm going to disagree with the concerns expressed here regarding the use of ASV in conjunction with general heart disease, and perhaps even for the specific cohort that was indicated as having a 2.5% increase in mortality risk with ASV. That Cohort was specifically individuals with congestive heart failure with left ventricle ejection efficiency less than 45%. If you have A-fib or have had bypass or other heart conditions, this is NOT your concern. Even the cohort found to be at higher risk by the Resmed study was an unexpected result, and one that is being challenged in newer studies, because the resmed study used outdated older machines, and considered individuals "treated" with 3-hours or more of use each night. Hell, CHF patients have a high probability of being deceased within 5-years of diagnosis regardless of ASV or PAP therapy.

Don't let this potentially erroneous study keep you from getting treatment that can improve your health and prevent advancement of heart disease, especially when it doesn't even apply to your condition. ASV provides the PAP therapy to resolve your OSA, and breath by breath pressure to resolve periodic breathing and centrals.

Thanks for the advice, Sleeprider. We seem to have consulted some of the same literature, which supports what you have to say.

I have been on APAP only since November, and I continue to improve by using this safe and relatively inexpensive therapy. My plan is to see how much farther I can go with it. At that point it will be time to decide, with the help of proper medical advice, whether that is far enough. If it's not, the next step would likely be ASV. And I would certainly pony up for it if both my sleep specialist and my cardiologist recommend it for my case.

Sound good?