How does ResMed EPR affect AHI

I am back on CPAP therapy after a 5 year break. After a week of looking at the data I am currently using an auto setting of 10-15 and EPR off. At 10 breathing against the pressure is not too bad but I have a significant amount of difficulty exhaling against 15. I understand that EPR can help with that but was advised to turn it off. What am I looking for in the data to decide why EPR should be on or off?

EPR is largely a comfort issue, for MOST, but not all people. Some, like myself, have no problems at all exhaling against higher pressures. On the contrary, I find the EPR disturbing.

I can't give a great answer to how EPR changes AHI, if at all. I *think* that if you are seeing a lot of central apneas, EPR (and more to the point, a bi-level system) can help.

I bet you'll get better answers shortly...

corvous256 wrote: ↑

Wed Jun 17, 2020 9:58 am

I am back on CPAP therapy after a 5 year break. After a week of looking at the data I am currently using an auto setting of 10-15 and EPR off. At 10 breathing against the pressure is not too bad but I have a significant amount of difficulty exhaling against 15. I understand that EPR can help with that but was advised to turn it off. What am I looking for in the data to decide why EPR should be on or off?

How often is your machine running at 15?....If it's a often, your max pressure should be increased.

Adding in EPR or a drop during exhale can sometimes affect the AHI in that the AHI will increase because the pressure during exhale drops to a level where the airway can't be held open well enough to prevent the airway collapse.
It isn't always a given that this will happen though or how much of a negative impact it will have. It all depends on if that prior minimum pressure was right at the line where just below that pressure the airway is unstable or if there is a bit of wiggle room before it becomes more unstable.

So try it. Add in EPR and watch your AHI. If it changes much then we re-evaluate things based on what changed and how much.

Now if your central apneas increase because of EPR we have a different sort of problem.
You can't be trading one kind of apnea for another.

IMHO EPR will almost always result in a slight increase in a (slight) increase in obstructive related events. When one uses EPR the net effect is less pressure at exhale, and less pressure typically means less effective treatment.

Having said that, taking advantage of EPR (or higher PS) can reduce AHI because it can be helpful in allowing us to tolerate higher pressure on inhale.

IE

Let's assume one is on fixed pressure of 13 CM

If EPR is turned on maximum of 3, then during inhale the pressure is at 13, but during exhale the pressure is at 10. The net effect is a reduction of pressure half the time of 3 CM.

But, if one were to increase the pressure to 16, and turn on EPR to 3. Thus giving a similar exhale experience to fixed 13. The net effect is an increase of 3 CM for half the time.

As others have said, EPR is a comfort feature, but it can also allow higher pressures to be used and tolerated for this who have trouble tolerating higher pressures on exhale.

Alarms went off in my head

Please see this thread
viewtopic.php?f=1&t=179495&p=1355863#p1355863

EPR could well be causing central apneas.

So if you need 10 cm for obstructive apnea control AND EPR at 3 is causing centrals you might try just a little EPR and see what happens both in terms of OA management AND central apnea prevention.

Maybe try EPR at 1 and see what happens. Don't increase your minimum pressure of 10 either...the bulk of your AHI isn't obstructive and you don't need more pressure AND it might make things worse.
One change at a time and then evaluate results.