Help me understand C-Flex (the plot thickens)

[Catnap]

Because of the issues I'm having with my DME, I requested a copy of my CPAP Rx. It arrived in today's mail, and it doesn't look to me as if the prescription was filled correctly to begin with. The prescription specifies a machine with C-Flex. As far as I can tell, my machine doesn't have that sort of technology. If I understand correctly, C-Flex is a Respironics proprietary technology. Is it possible for a non-Respironics machine to have similar technology? I looked at the description for my machine on cpap.com, and it does not look to me as if I have it.

Also, interestingly enough, the prescription says that I "might" find heated humidification helpful and suggests it be "offered." The DME's interpretation of offering it to me was to show me only one machine and then bill me an additional $300 over and above the cost of the machine because that machine has integral humidification. While I probably would have wanted the heated humidification, selling it to me without explaining any other choice does not meet any definition of "offer" that I've ever seen.

Anyway, can you help me understand C-Flex and whether it might also be an integral part of a non-Respironics machine?

[Hawthorne]

As far as I know, C-Flex technology is exclusive to Respironics machines. Resmed has something like it (EPR I think) but it is not called C-Flex. I'm sure it is not on Fisher & Paykel machines.

It sounds like the DME gave you machine he had "on hand", regardless if what the prescription said. It's either that or, the person who dealt with you at the DME's never saw the prescription.

[Plowboy]

Who is your insurance provider?

[BlueSky72]

As far as I know, only Respironics and Resmed have C-Flex/EPR-type technology. Resmed's EPR is Expiratory Pressure Relief and that's the most accurate term for what the function is. It's just a lower pressure setting for expiration (breathing out). At higher pressures it's absolutely essential, IMHO. Respironics's C-Flex (A-Flex on Auto machines) is also a lower pressure setting for expiration, but it works differently to Resmed's EPR.

I've experienced both EPR and C-Flex at 17cm H2O, and they are different, subjectively and objectively. The best AHI I got with Resmed was 8.0, and with Respironics on the same pressure setting of 17cm was 4.9 and still dropping. So, while it makes a huge difference whether you use a form of expiratory pressure relief or not, it makes a small difference whether your have Resmed EPR or Respironics C-FLex/A-Flex. For some of us, that small difference is very important.

When you come to choose your next machine (which will hopefully be soon and at no cost to you because of your incompetent DME), if your AHI is consistently below 5.0, then you might feel free to consider all the different usability and comfort features of the machines. But if you happen to be in the group of people still trying to get below 5.0, then you might find Respironics more suited to your needs. Hopefully you can take a machine home for a month's trial and if it doesn't work out, you can get another. But I guess that depends on your insurance.

IMO, everyone should have a machine with options for C-Flex/EPR, heated humidification and full data capability. I guess not everyone has all these because prescribers don't always understand the need for them, and DMEs take the opportunity of selling cheaper machines for greater profit. Provided the prescriber knows their importance (and which machines have them) then DMEs will be required to supply them.

Good luck

[Catnap]

Sounds like a good approach, Bluesky. Am still waiting to hear the final upshot from insurance -- called them two days ago and they said they'd call back in 2-3 days. Unfortunately, current machine provides only compliance data (won't make THAT mistake again, either), so I really don't know how I'm doing. Subjectively, I am clearly much better than pre-CPAP, thankfully.

[rested gal]

Hawthorne and Bluesky are right. The F&P machine they gave you has no exhalation relief feature at all.

ResMed has EPR as its pressure relief feature for exhaling.
Respironics has C-Flex.

As Bluesky said, those two proprietary features work quite differently from each other, and do feel different in how they go about their job.

In a nutshell, Respironics' C-Flex gives its greatest drop right at the beginning of the exhalation, and the amount of pressure drop depends almost entirely on how forcefully the person starts to breathe out each time. The regular pressure is allowed back in before the exhalation is completely finished.

ResMed's EPR winds the pressure down as the exhalation is underway, giving some (but very little) drop right at the instant you start to breathe out. The amount of pressure drop that it will eventually go down to during exhalation can be set in exact cm's -- 1, 2, or 3 cms of drop in pressure. The regular pressure does not come back in until you start to inhale again, or until a number of seconds have gone by -- whichever comes first.

On another note -- while it's true that some people are treated better by one machine rather than another, I personally wouldn't base a decision about which machine (ResMed or Respironics) might give me better treatment because one gave me a lower "AHI" than the other. There can be many reasons why one might be more suitable for a person than the other, but if it's only based on a comparison of AHI between a ResMed machine and a Respironics machine, that might be a little like comparing apples with oranges.

Since the machine manufacturers each use their own different definitions for "hypopnea", there can be quite a bit of difference (usually a higher "HI" -- hypopnea index -- score) from ResMed machines, compared to Respironics machines. The hypopnea index is added in with the apnea index to produce the "AHI" (apnea/hypopnea index.)

So, it's not unusual for the same person to see a higher AHI when using a ResMed machine than when using a Respironics machine, yet be getting equally effective treatment with either one.

There's also the possibility, imho, that for some people the pressure needs to be set a little higher to get effective treatment with a ResMed machine when using EPR (especially EPR at "3" ) if the prescribed pressure setting was already pretty much right on the fine line for preventing apneas. Apneas that might hit at the end of the exhalation when EPR is still holding the pressure down, waiting for you to inhale...or for enough seconds to tick by before bringing in the prescribed pressure again.

I'm not a doctor or anything in the health care field, so I might be stating some of that wrong. Just my opinion.

[dsm]

The F&P machines are very nice & well made but, they have historically not had C-Flex nor C-Flex like functions & nor have they had data recording. I do though think they recently introduced a new high-end model that does but would need to check.

As for them billing you an additional $300 because it has humidification (as mentioned, a built in feature) that smacks of outright 'gouging'.

ADDED WHILE WRITING THIS POST ...
Here is F&Ps product range & indeed there is the 608 which is an auto & I believe gathers data. That also has a heated air tube.
http://www.fphcare.com/osa/diagram03.asp

That could be a very nice machine.

DSM

[preemiern]

The DME HAS to fill your prescription AS ORDERED BY YOUR DOCTOR!!! It is absolutely illegal for them to use anything other than what the Dr. prescribed. If your dr. ordered a machine with C-Flex, then they have to give you a respironics machine with c-flex!!! I would take that machine back, and demand they give you what was ordered, WITH the humidifier. I would threaten them with contacting an attorney if they don't. It would be like me as nurse deciding that I want to give my patient more or less of a medication than what was ordered by the dr. If I did that, I would lose my nursing license.

[BlueSky72]

Thank you rested gal for explaining it so much better than I could I've been trying to be cautious about how I express the increase in efficacy I've had from switching machines, as I don't have studies or documentation I can refer to.

According to my RT, I'm in a tricky position of needing a high pressure to prevent obstructive events, but also getting central and mixed events from a medication I take. Even at 16cm, snore was detected by the home sleep study kit I was using. (I'd love to know how to monitor snoring using my machine). So my pressure went up to 17cm, then to 17.5cm. I also had a lot of discomfort in the first few weeks at this pressure but I must have gotten used to it as it doesn't seem so bad now. I changed from a Resmed to a Respironics for other reasons, and initially was unhappy with the Respironics because the pressure felt way too high (it was 17.5cm), and it seemed so loud I wouldn't be able to sleep. Well, I became used to the noise because I learned from someone online that the machine might be better for me because of the difference in the algorithms.

I only used my AHI as a shorthand way to say the therapy is more effective for me. I guess one way to be sure would be to use an independent monitoring device while using one machine then the other. To me, the explanation of how the different expiration pressure levels work seems to account for the improved efficacy. I'm certainly not saying there is anything wrong with the Resmed machines, but for someone who needed a little more 'grunt' without increasing the pressure level, I'm glad I am using a different one. I do feel better, ie less daytime sleepiness, and I'm excited to have broken through the 5.0 AHI barrier, even if a different scoring method had something to do with it.

When I have saved my pennies and am ready to consider a BiLevel, then Resmed will have another shot at winning my affections There's a lot to be said for an ASV machine that goes up to 25cm. Their machines are pretty too

[dsm]

<snip>

There's also the possibility, imho, that for some people the pressure needs to be set a little higher to get effective treatment with a ResMed machine when using EPR (especially EPR at "3" ) if the prescribed pressure setting was already pretty much right on the fine line for preventing apneas. Apneas that might hit at the end of the exhalation when EPR is still holding the pressure down, waiting for you to inhale...or for enough seconds to tick by before bringing in the prescribed pressure again.

I'm not a doctor or anything in the health care field, so I might be stating some of that wrong. Just my opinion.

I also agree wholeheartedly with RestedGal re EPR and setting your 'base' cpap pressure higher if on Epr of 3 (perhaps even 2). This principle apples to taking your cpap pressure across to a bilevel - if you were titrated at 12 CMs & want to use a Bilevel set with for example 3 C CMs epap to ipap gap, then up your base pressure by at least 1 CMs so that ipap goes to 13 CMs & epap to 10 CMs. EPR & Bilevel are very similar in this respect.

C-Flex is and was a great innovation that helps reduce the effort to breath out against a fixed pressure. It momentarily drops the pressure as you start to breath out but resumes the pressure approx 1/4 to 1/3 the way into breathing out & does so with a rush. This sudden resumption of pressure has always been a great source of aerophagia and if you know what I mean, 'mouth pops' (when your mouth pops open and a bubble of air bursts forth).

C-Flex at 3 can be too much for people with such issues. Each type of pressure reduction has its good points & bad points but they do help greatly over a machine without the options. Having used both over a good period, I lean towards EPR but that is just my pref as I am an avowed bilevel advocate.

Cheers & good luck

DSM