Why is increasing EPR eliminating h and fl

[Walla Walla]

Ron, I know flex is different than EPR. I'm just talking about EPR. If I put my EPR at 3cm and my pressure is set at 15cm than the exhale pressure is at 12cm. At least that what the machine says is happening on Sleepyhead and ResScan. So how does it cause it to have the effect of 13cm?

yankees123, It doesn't affect the maximum pressure just the minimum.

[Ron AKA]

I didn't know that epr effects both the minimum and the maximum pressures.  I though it only effected the minimum pressure when you exhale.

It doesn't directly affect the maximum or minimum pressure. It affects the actual therapy pressure. If your machine is set with a max of 15 and min of 10, you will get a therapy IPAP pressure somewhere between those two limits. On a breath by breath basis EPR reduces the exhale or EPAP pressure by say 3 cm. That means if your therapy pressure is at maximum EPAP will be 12 cm (nominally). And if your therapy pressure is at 10 cm, then your EPAP will be at 7 cm. Again nominally.

[yankees123]

I think I understand now.  Thanks!

[Ron AKA]

Ron, I know flex is different than EPR. I'm just talking about EPR. If I put my EPR at 3cm and my pressure is set at 15cm than the exhale pressure is at 12cm. At least that what the machine says is happening on Sleepyhead and ResScan. So how does it cause it to have the effect of 13cm?

You are talking theory, and I am talking actual practice. Keep in mind that the Pressure (IPAP and EPAP) is a demand signal from the machine. It is not actual pressure. Mask pressure is theoretically actual pressure, but since there is no pressure pickup in the mask itself, the mask pressure is really a best guess estimate, that tries to compensate for flow rate, flow pressure loss, hose length, and mask pressure loss. The real question here is whether it is IPAP or EPAP that determines when there will be an obstruction. When there is no EPR then they are the same, so it is a moot point. When you have EPR on then you get a wave form for pressure. What pressure in that actual wave form determines when an obstruction will occur? Is it the very minimum on exhale or some other point. 

Lets take the confusion of max and min pressure out of it, and just consider a fixed pressure setup. Say it is set at 10 cm and apena is well controlled. If then you turn EPR of 3 on, what do you have to set pressure at to equally well control apnea? Theory says 13 cm. I am suggesting in actual practice it is more like 12 cm. That is just my observation/opinion. Yours may be different. I think that is why we actually have to try these settings to see what they do, and not just assume we can predict what they will do. In other words the proof is in the pudding, not in the recipe!

[Walla Walla]

Ron, With all respect your pudding is based on limited data.

[Rcgop]

Thanks Sleeprider,
You are spot on and I have proof. Now the light has come on for me and I will be making some additional "comfort" setting changes. Don't tell me EPR is only a comfort setting.
EPR has lowered my H Index without having any affect over the CA Index and the OA Index is well under control. I have also noticed my leaks are much lower with the use of EPR.

I will let the numbers speak for themselves

Beginning Ending      Days      Pressure   EPR    H Index OA Index CA Index
                                      Min   Max    
03/09/16  05/09/16  62     4.0   16.0       off     1.21         0.06         2.94  Before I discovered Apnea Board
05/26/16  06/07/16  13     5.0   16.0       1       0.31         0.08         0.66
12/10/17  12/24/17  15     6.2    8.0        3      0.19         0.04         0.43
12/25/17  01/31/18  38     6.2    8.0        2      0.17         0.02         0.35
02/01/18  02/24/18  24     6.2    7.8        2      0.13         0.02         0.24
02/25/18  03/30/18  34     6.2    7.8        1      0.25         0.02         0.34
03/31/18  04/18/18  19     6.2    7.8        off    0.73         0.01         0.31
04/19/18  04/20/18    2     6.2    7.8        1      0.06         0.00         0.68