Cflex 1-3 Levels

Ok, what's 1-3 mean. I accidently hit that button in the middle of the night and I forgot what it had and what it meant! Uggh. Used the search here and could not find the definitions. Went to the product site, same thing. No luck.
Thanks.

It's exhalation relief, by one, two, or three cmH2O. It makes it easier to exhale by lowering your pressure during the exhale phase of your breath.

A ResMed machine's "EPR" (expiratory pressure relief) does drop the pressure for exhaling by exactly 1, 2, or 3 cm's, corresponding to EPR's setting choices of 1, 2, 3.

C-Flex in a Respironics machine works differently. The C-Flex settings of 1, 2, 3 do reduce the pressure when you start to breathe out. But not by exact cm's.

C-Flex 1 gives "some reduction" in exhalation pressure

C-Flex 2 gives "a little more reduction" in pressure

C-Flex 3 gives "the most reduction."

The C-Flex drop in pressure for exhaling is not exact, the way EPR is in a ResMed machine. The amount of pressure reduction you get with C-Flex (at any C-Flex setting) is very dependent on how forcefully you happen to breathe out.

If the beginning of your exhalation is rather forceful (think of a strong "HUFF!!") C-Flex will make the pressure drop more than if you start your exhalation very softly. You could get varying degrees of pressure drop at the same C-Flex setting (C-Flex set at 3, for example) from one exhalation to another -- each time you breathed out, the actual amount of pressure reduction you'd get would depend on how strong or light that particular exhalation of yours happened to be.

There are other considerable differences between ResMed's EPR and Respironics' C-Flex, but the fact that one (ResMed) gives exact pressure reduction in cm's according to the 1, 2, 3 EPR setting, and the other (Respironics) gives a vague drop of "some", "more", "most" for the 1, 2, 3 C-Flex setting, is one of the biggest differences between the type of exhalation pressure relief offered by those two brands.

RG, thanks for the clarification about the Respironics machines!

RG, Now I finally know! I don't think you ever explained it exactly that way although God knows, you've explained it in a hundred different other ways before! So now I know why Mike was bothered by the flex, because he is probably one of those people who has an "uneven" exhale pattern, not always the same, and said he sometimes felt "rushed"to take his next breath. We don't use that feature but I'm just fascinated with the technology.

Has anyone been told by their doctor not to use A-flex or C-flex? Any idea why a doctor would recommend that?

Dori, it may not have been the varying drop in pressure that C-Flex gives depending on the forcefulness or softness of one exhalation from another that made your husband feel as if the machine was rushing him to inhale again before he was ready to.

It more likely was one of the other "differences" about Respironics' C-Flex (compared to ResMed's "EPR") that was giving him that feeling.

C-Flex is designed to give most of its drop in pressure at the beginning of the exhalation...at the very start of breathing out each time. It's also designed to let the regular pressure come back in BEFORE the person is completely finished breathing out. That feel (if the person feels it) of more pressure coming back in while the person is still trying to breathe out can be unsettling. Can make you feel like you're supposed to breathe in again, even though you're still breathing out.

One poster who couldn't stand C-Flex wrote about "breath-stacking" -- waking up at night practically panting because even in sleep his body was apparently sensitive to that "feel" your husband described. The fellow (WillSucceed is his nickname) was apparently trying to breathe in prematurely even during sleep. He couldn't use C-Flex even at the lowest setting.

That design of C-Flex has a good purpose, though. If the airway begins to collapse as breathing out dwindles, and if the airway does close during the pause after exhalation, before the person STARTS to breathe in again, the collapse could keep the person from even being able to get a new inhalation started. He'd be having an apnea.

By designing C-Flex to let the therapeutic pressure back in BEFORE the person is going to naturally start to inhale, the collapse can't happen. The needed pressure to keep the airway open will already be in place so that the person can START to breathe in again.

My previous post described how C-Flex is designed to let the therapeutic pressure back in before the exhalation is finished, so that the airway is held open, ready for the person to breathe in again.

ResMed's EPR works quite differently. While C-Flex gives its most drop at the START of the exhalation, EPR seems (to me, anyway when I've used it) to not give its full 1, 2, or 3 cm drop in pressure at the moment when a person first STARTS to breathe out. EPR feels to me as if the pressure moves down as the exhalation continues. The full exact 1, 2, or 3 cm pressure reduction is in place at some point during the process of breathing out and STAYS DOWN all the way through the end of the exhalation.

At the end of breathing out AND during any pause that might happen before the person starts to breathe in again, EPR continues to maintain its exact 1, 2, or 3 cm drop in pressure. EPR waits until the person STARTS to breathe in again before it lets the therapeutic pressure in again. That's very different from the way C-Flex lets the therapeutic pressure back in again BEFORE the person is even completely finished breathing out.

But what if collapse of the airway happens because an EPR setting of "3" gives 3 cm less pressure than is needed to prevent that person's apneas? What if a person has been prescribed a CPAP pressure of 10, and the 7 cm being delivered during an EPR setting of "3" (to drop the exhalation pressure 3 cms) lets an apnea happen? How will the person even be able to breathe in again, to make EPR stop holding the pressure down during the pause? How will you get the therapeutic pressure of 10 going again?

There's a safeguard built into EPR for that kind of eventuality. If the person has not started to breathe in again within so many seconds, EPR is suspended, the therapeutic pressure is allowed back in, and... hopefully, the airway is splinted open again. The person can draw a new breath. EPR will stay "off" until normal breathing resumes, then EPR will start doing its thing again.

That's why I often suggest that if a person is going to use EPR, they might want to set their CPAP pressure (or their minimum pressure with a ResMed autopap) 1 or 2 or 3 cm's above what was prescribed. That would insure that the therapeutic pressure WAS, indeed, still in place, so the person could draw in a new breath in a timely fashion.

They'd still get the comfort benefit of EPR because a higher pressure for inhaling generally is not uncomfortable, and it's the relative difference between inhaling (at a higher pressure) and exhaling (at a lower pressure) that makes "CPAP breathing" with EPR turned on feel natural.

Quite a few people on the message board have written about lowering their machine-reported AHI when they turned EPR off. In most of those cases, I'd bet they'd have gotten that lower AHI if they had raised their prescribed pressure approximately the same number of cm's that they had set their EPR for, and left EPR on.

So, there are plusses and minuses about how those two very different-from-each-other exhalation "comfort" features work. The two manufacturers have gone about designing their relief from pressure during exhalation the way they thought best. Not to mention that patents had to be considered!

Some like one, some like the other, some prefer using neither manufacturer's exhalation relief feature. It's good to have choices.

RG, As I was reading along(and even experimenting with my own breathing, c'mon I wasn't the only one!),I kept saying..but what about...and sure enough there it was the answer in the next paragraph. Although it's a moot point now, what I'm gathering from this is that Mike would probably have been more compatible with the Resmed EPR technology and might have had an easier transition to cpap life. But we're looking forward not backward so it's all good. Thanks so much, Dori

RG, thank for such a clear explanation. Though I still have to read it a few times before it will sink in.

And Dori, yes I did breathe along, as I was reading it.

rested gal wrote: At the end of breathing out AND during any pause that might happen before the person starts to breathe in again, EPR continues to maintain its exact 1, 2, or 3 cm drop in pressure. EPR waits until the person STARTS to breathe in again before it lets the therapeutic pressure in again

Wouldn't that depend on the INHALE setting? If it is set to MED then that might be true. But if it is set to FAST then it would not apply? In this case it would work the same as C-Flex?