Why is this?

cpapjack · Post by **cpapjack** » Wed Oct 18, 2006 6:16 am

Last night I set my Vantage to work in straight CPAP mode at a pressure of 10 with EPR on 3. Wow, the EPR was really nice. I am able to sleep fine without the EPR in APAP mode, but this has me thinkin now. Anyway, when I woke this morning and looked at my stats on the LCD display, the 95% pressure showed 8.8. Why, if the machine is set to function as a CPAP at 10, why would it show that it ran at 8.8 or less 95% of the time as to running at 10 the whole night?

Jack

DreamStalker · Post by **DreamStalker** » Wed Oct 18, 2006 7:07 am

Becasue you used EPR ... EPR works on exhale ... since you spend about half of your time exhaling and if you set EPR to 3, the average of 7 and 10 is about 8.5 plus or minus a couple of tenths. Add to that the fact that numbers are rounded up to the nearest even decimal and you get 8.8.

- r

whatrdreamsmadeof · Post by **whatrdreamsmadeof** » Wed Oct 18, 2006 7:48 am

The same thing happens to me and I have the same machine it is unerving.................hang in there..........Ellen

GoofyUT · Post by **GoofyUT** » Wed Oct 18, 2006 7:57 am

I believe that Roberto's explanation is right on, but this same thing has been reported by many and remains a mystery. However, here's the thing: You ARE getting sufficient pressure to keep your airway patent and that's all that matters. So, relax and enjoy it!

Chuck

cpapjack · Post by **cpapjack** » Wed Oct 18, 2006 8:05 am

Becasue you used EPR ... EPR works on exhale ... since you spend about half of your time exhaling and if you set EPR to 3, the average of 7 and 10 is about 8.5 plus or minus a couple of tenths. Add to that the fact that numbers are rounded up to the nearest even decimal and you get 8.8.

Roberto, your explanation makes perfect sense. Thank you for the reply.

You ARE getting sufficient pressure to keep your airway patent and that's all that matters. So, relax and enjoy it!

I know, I'm not worried or anything, just curious. It sure did feel nice.

ozij · Post by **ozij** » Wed Oct 18, 2006 10:34 am

Bravo, Roberto!

O.

Maryb · Post by **Maryb** » Wed Oct 18, 2006 10:53 am

I have been struggling with aerophagia. I finally tried CPAP mode with EPR (for the past 3 nights) and like CPAPJack, I really loved it. It's just so much easier and more comfortable. I find I swallow less air and as an added bonus for some reason my mask leakage is WAY LESS.
I used a pressure setting of 9 and an EPR of 3. My aerophagia was better too.
The trouble is that my AHI numbers were too high (7.6 on night #1 and 10 on the two subsequent nights). So I guess I'll have to turn the pressure up and see if I can still keep all the nice benefits of EPR.

Maryb

DreamStalker · Post by **DreamStalker** » Wed Oct 18, 2006 11:24 am

Maryb wrote:I have been struggling with aerophagia. I finally tried CPAP mode with EPR (for the past 3 nights) and like CPAPJack, I really loved it. It's just so much easier and more comfortable. I find I swallow less air and as an added bonus for some reason my mask leakage is WAY LESS.
I used a pressure setting of 9 and an EPR of 3. My aerophagia was better too.
The trouble is that my AHI numbers were too high (7.6 on night #1 and 10 on the two subsequent nights). So I guess I'll have to turn the pressure up and see if I can still keep all the nice benefits of EPR.

Maryb

I have a working hypothesis for the Hybrid/AHI issues that may explain why some folks still feel refreshed despite bad AHI numbers. It appears that those with higher pressures (over about 12 cm) get fairly good AHI values whereas those with lower pressures get inconsistent AHI numbers. I think the relatively large volume of the Hybrid mask interior and consequential CO2 exhaust flow rate causes the pressure transducers in the PAP machines to be less sensitive to normal transient pressure changes of breathing. The transient response to pressure changes is probably diminished by the mask volume/exhaust flow rate more so at lower pressures. Both APAP and EPR modes would seem to make the transient response still even worse. Anyway, this may also explain Chuck's observation that S8 autos (w/ their more agressive algorithm) do not match as well to the Hybrid.

I’ll have to do some research into some fluid flow mechanics and see if my guess is on the right track … a topic for another post. Perhaps some of our members with an engineering background can start a new post regarding this issue.

- r

svh · Post by **svh** » Wed Oct 18, 2006 11:42 am

Interesting theory about the Hybrids....I am considering which mask to get next, and want something ff to allow for winter colds, etc. I am (relatively) happy with my swift, apart from how loud it is, but I want to get something else to allow for mouth breathing when necessary. Since my pressure is below 10, I eagerly await your analysis.

Maryb · Post by **Maryb** » Fri Oct 20, 2006 12:12 pm

Roberto-
I felt even better when I increased the CPAP pressure to 10.6 (up from 9). My AHI dropped back down to below 5. So it was simply a matter of not enough pressure for me at CPAP 9.
Meanwhile, the EPR is still great and helping with the aerophagia.
So it looks like it's CPAP with EPR for me for the time being (instead of APAP with no EPR).
Even better would be APAP with EPR -- I guess that would be an auto biPAP machine, right?

Maryb

Maryb · Post by **Maryb** » Fri Oct 20, 2006 12:14 pm

Roberto-
I felt even better when I increased the CPAP pressure to 10.6 (up from 9). My AHI dropped back down to below 5. So it was simply a matter of not enough pressure for me at CPAP 9.
Meanwhile, the EPR is still great and helping with the aerophagia.
So it looks like it's CPAP with EPR for me for the time being (instead of APAP with no EPR).
Even better would be APAP with EPR -- I guess that would be an auto biPAP machine, right?

Maryb

rested gal · Post by **rested gal** » Fri Oct 20, 2006 12:39 pm

GoofyUT wrote:However, here's the thing: You ARE getting sufficient pressure to keep your airway patent and that's all that matters.

Some people may be getting sufficient pressure, but some may not when using EPR at their sleep study titrated "prescription" single pressure.

Maryb wrote:I used a pressure setting of 9 and an EPR of 3. My aerophagia was better too.
The trouble is that my AHI numbers were too high (7.6 on night #1 and 10 on the two subsequent nights). So I guess I'll have to turn the pressure up and see if I can still keep all the nice benefits of EPR.

Maryb wrote:Roberto-
I felt even better when I increased the CPAP pressure to 10.6 (up from 9). My AHI dropped back down to below 5. So it was simply a matter of not enough pressure for me at CPAP 9.

What MaryB describes may be a good example of what sleepydave brought up a year ago on the apneasupport board -- the possiblilty of some people getting sub-therapeutic pressure when using EPR with their prescribed titrated pressure:

Oct 05, 2005 subject: Is EPR Really Bilevel? sleepydave (RRT, RPSGT, manager of an accredited sleep lab) discusses ResMed's EPR feature.

Excerpt:
"The baseline pressure returns to 10 cmH2O, but not until after inspiration has begun. In other words, inspiration is the trigger to terminate EPR, and instead of a CPAP pressure of 10 cmH2O with an expiratory adjunct, we are effectively left with BiPAP of 10/7
<picture of a graph>
This might not make a clinical difference if the patient ends up with the same results on BiPAP 10/7 that he would have on CPAP 10 cmH2O (which could be the case if there were only flow limitations, snores, or hypopneas). But if the new EPR-defined EPAP is below the apnea threshold, then there could be a problem. <bold emphasis mine>

In the second graph, the waveforms are superimposed to show more clearly that inspiration is occurring at a sub-therapeutic level:"
<another graph>

Bob... · Post by **Bob...** » Fri Oct 20, 2006 1:00 pm

Another advantage I have found with EPR is a reduction in mouth leaks. They are down to the point I no longer need to tape, and that is indeed NICE!

Bob

Goofproof · Post by **Goofproof** » Fri Oct 20, 2006 1:13 pm

[quote="Maryb"]Roberto-
I felt even better when I increased the CPAP pressure to 10.6 (up from 9). My AHI dropped back down to below 5. So it was simply a matter of not enough pressure for me at CPAP 9.
Meanwhile, the EPR is still great and helping with the aerophagia.
So it looks like it's CPAP with EPR for me for the time being (instead of APAP with no EPR).
Even better would be APAP with EPR -- I guess that would be an auto biPAP machine, right?

Maryb

cpapjack · Post by **cpapjack** » Fri Oct 20, 2006 1:26 pm

Maryb wrote:Meanwhile, the EPR is still great and helping with the aerophagia.

That's funny you should say that. I thought that APAP's were supposed to reduce aerophagia. I know in my case it does. I've noticed aerophagia come back with a venegance since I switched my machine to straight CPAP. I think I may switch it back to APAP tonite and see what happens.

Jack

Why is this?

Why is this?

me tooooooooooooooo

Stats (redux)

CPAP mode with EPR

Re: CPAP mode with EPR

EPR

Re: EPR

Re: EPR