Brain fog only makes this harder, especially when we start throwing around the jargon
The problem is that EPR is kind of an afterthought. The morons of sleep medicine think it's some "comfort feature" that they throw at us whiny idiot patients, when it is a vital component of therapy if you have a particular form of sleep-disordered breathing.
CPAP is something that has evolved over decades, and the language gets set in stone and then we learn more stuff and the language we started with doesn't make sense anymore.
-- So we started with straight CPAP, with a constant pressure. There is this whole rigamarole of "titration" where you are in a lab and the tech is controlling the pressure up and down and zeroes in on THE perfect pressure for you, and that's your prescription. Except that in real sleep apnea, that's like trying to nail jello to the wall -- the "right" pressure is moving around all night and is different on different nights.
-- So now we come to the APAP, where these astonishingly clever engineers came up with sensors where the machine follows what you are doing continuously and raises and lowers the pressure so you get the right pressure for right now.
-- Well except that pressure getting really high can get to be uncomfortable, so let's add on a feature on these high-pressure machines (a bipap goes to 25 while an APAP goes to 20) which give the patient a lower pressure on the exhale side.
-- The clever engineers then added some limited pressure support thingy to the APAPs and they called it EPR because they thought that the "regular" cpap users could do with some extra comfort, too. Because it's all about high pressures, they didn't even think about what happens when the gap between inhale and exhale pressures that you ask for is larger than the gap between the minimum pressure that you asked for and the minimum pressure that the machine can do.
-- Well except that it turns out that lowering the pressure on the exhale side isn't just a comfort feature for high pressures, it can actually cure UARS (like with me!) at really minimal pressures.
So now we have this machine that cures UARS when used in a mode that the engineers weren't even thinking about when they engineered the user interface, and confusing language because they didn't invent language to talk about things that they weren't thinking about!
There is one user interface tweak that they could do that would sure make things clearer...
Have the user dial in the EPR
first, and then when it comes to dialing in the minimum pressure or the ramp pressure, you don't allow the dial to roll down below 4+EPR. So if you set your EPR to 3, you wouldn't be able to set your minimum to below 7. EPR of 2, minimum can't go below 6, etc.
Part of the problem as well is that the sleep medicine idiots are fixated on the patients' stupidity as being the only problem with sleep therapy. If they could only bully or trick us self-destructive dumbbells into "compliance" then the machine itself is magic. Dialing in proper therapy for real patients with complex problems takes skill, intelligence, experience, intuition -- you know, practicing medicine. Being an effective bully, salesman, and/or con-man is a completely different skill set. So they get derailed when something gets invented as a "comfort feature" because they think this is about convincing us. With EPR (which I actually find mildly annoying and less comfortable than no pressure support) they are just completely off the rails. Since they think EPR is snake oil, they want to be as confusing as possible when it comes to selling it to you!