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Respironics A-Flex vs. C-Flex

For all of you who don't know the difference between A-Flex and C-Flex on Respironics CPAP machines, you're in good company. Each is a comfort option on the most popular Respironics CPAP machines that makes it easier to tolerate CPAP treatment. A-Flex is a little more comfortable than C-Flex, in that it provides pressure relief on both inhalation and exhalation. C-Flex only provides pressure relief on exhalation.

However, there is often a trade-off between comfort and the most optimal treatment, and that certainly is the case with the distinction between A-Flex and C-Flex. When a CPAP machine's algorithm allows for pressure relief, that of course means the pressure is being reduced. But the very reason we use Positive Airway Pressure in the first place is to have that pressure. So when the pressure is reduced, we are at greater risk for having apneas and hypopneas. On the other hand, if we can't tolerate the pressure without the comfort settings switched on, we will not use the treatment at all, and our machines will become doorstops. A-Flex, one prominent sleep physician told me, is considered the "training wheels" of CPAP therapy because it is the ultimate in comfort settings, and can get people used to CPAP therapy until they are ready to go to the next step, which would be C-Flex. Ideally, though, we'd wean ourselves off both comfort settings, and optimize our treatment in the process.

Most doctors won't tell you about the purposes of these settings, and how to view them in the context of your overall treatment. We at SleepGuide hope you take this information into the total mix of information as you make your CPAP treatment decisions.

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Comment by Judy on January 24, 2009 at 7:26pm: Daniel, at some point I just found it more comfortable w/o Ramp and eventually also found it more comfortable w/o EPR and C-Flex as well. It had nothing to do w/my AHI and everything to do w/being more comfortable w/o. Its like some of us find it more comfortable to stay in Auto mode if we have an Auto whilst others of us find it more comfortable to NOT have the constant pressure changes once we've found that "sweet spot" of pressure level(s) I guarantee you I am a creature of comfort whether it is CPAP therapy or choice of clothing..

Comment by Daniel on January 24, 2009 at 7:09pm: As long as your symptoms are being relieved and your AHI is below 5, what's wrong with being comfortable? I have to object to the notion of "weaning off comfort settings." While most people who are successful with CPAP eventually ditch the ramp feature, I don't see any reason to wean yourself, as long as the therapy is effective.

Comment by Judy on January 24, 2009 at 6:17pm: Sorry, Spencer, I don't have the slightest idea about that.

Comment by Dave on January 24, 2009 at 5:54pm: Thanks for your feedback Judy. That insight on resmed is interesting. So your opinion is that exhalation pressure relief would probably not have an impact on hypopnea events?

Comment by Judy on January 24, 2009 at 5:38pm: Like you I no longer use or even like EPR or C-Flex (never tried A-Flex or any M Series device). They were nice features when I first started CPAP but in a very short time I turned off Ramp, Settling, EPR and C-Flex. I do think they are comfort features that can make acclimating to CPAP much easier for many of us.

Comment by Judy on January 24, 2009 at 5:33pm: I can't answer your question, Spencer, but it is pretty much widely accepted that the Resmed xPAPs tend to score hypopneas more aggressively than the other brands. There are some good Resmed interviews at the Talk About Sleep apnea support forum. I've read the explanation for why the Resmeds tend to score hypopneas more aggressively but I can't remember where nor the link. There was also at least one medical journal report on a study between a Resmed, a Respironics and a third brand I've forgotten and the slight differences between them - but again I didn't bookmark and don't remember where to find the link again. Grrrr.

Comment by Dave on January 24, 2009 at 4:30pm: I have successfully weaned myself off of first a GoodKnight 425 BiPap and then a M-series BiPap Equivalent. I switched to the resmed s8 autoset ii, because I wanted the auto adjusting pressure (w/o relief or bipap functionality) and didn't need the 'comfort' feature anymore. It seems I am having very few apnea events anymore and mostly hypopnea. I am so used the pressure now, that I often wonder if the machine is even on! When I am not sure, I purposely make a temporary leak in my mask by lifting it slightly and make sure the air rushes by!

I am also starting to wonder - what causes my hypopnea? Am I not exhaling fully due to the pressure, thereby preventing a full inhalation? So my main question now is - Now that I've tweaked my pressure well to get my apnea events close to 0, is it possible I may actually benefit medically (reduce my Hypopnea with no adverse affect on apnea events) from exhalation relief? or over time, might my body adopt (do breathing muscles strengthen?) and reduce my hypopnea events?