(09-13-2014 04:47 PM)Galactus Wrote: I don't understand how the machine is working, and the math that you are providing doesn't add up for me. My presumption is that is because I just don't get it. I think the one thing that I specifically don't get is the PS. I had thought till this post that PS raised and lowered EPAP and IPAP, but after reading this post I think I am revising that thought to understand that even though when we start at IPAP=EPAP+PS that is not to say these numbers depend on each other, or that PS raises them as I previously thought. It seems that in actuality IPAP EPAP and PS all raise and lower independently of each other based on their specific algorithms. Is that correct or am I still missing this?

Hi Galactus,

There are a few basic points on which we need to refocus, so that you will see more clearly how the machine works. After we focus on a few basic points, I think the math I provided earlier will make more sense to you.

Please forgive me for being repetitive in what follows.

Point #1. As you know, the basic definitional relationship is EPAP + PS = IPAP. This relationship is always maintained. It is never violated.

Point #2. Your machine has an algorithm for raising and lowering EPAP. I think the EPAP-adjusting algorithm never messes with PS. In other words, at the points in time when the EPAP is changed, PS isn't changed.

IPAP continues to equal EPAP + PS. In other words, at the points in time when EPAP changes, IPAP and EPAP move in tandem.

If you look at plots where EPAP did change, every time EPAP changed, both IPAP and EPAP moved in tandem. (Looking only at the times at which EPAP changed, you do see that IPAP and EPAP moved in tandem, right?)

Point #3. Your machine has an algorithm for raising and lowering PS. I think the PS-adjusting algorithm never messes with EPAP. In other words, when the PS changes, EPAP doesn't change.

IPAP continues to equal EPAP + PS. When PS changes, EPAP stays the same and IPAP changes.

In the plots you posted, if you want to see the times at which PS changed, these are all the times at which IPAP changed but EPAP did not change. (Looking at the plots, does this make sense now?)

Point #4. There is not a separate algorithm for adjusting IPAP. IPAP changes any time the EPAP-adjusting algorithm adjusts EPAP and any time the PS-adjusting algorithm adjusts PS, maintaining the relationship IPAP = EPAP + PS.

Point #5. There are settings (limits) for how low EPAP can go (the Min EPAP setting, which can be set as low as 4 but can be set higher) and for how high IPAP can go (the Max IPAP setting, which can be set as high as 25 but can be set lower).

EPAP can never be lower than the Min EPAP setting, but how high can it go as it auto-adjusts? It can go only as high as Max IPAP minus the present value of PS, so that the Max IPAP setting will not be violated.

Point #6. There is a setting which limits how high PS can go (the Max PS setting, which can be set as high as 8 but can be set lower). BUT, the PS will not necessarily be able to go as high as the Max PS setting would seem to allow it to go. A low Max IPAP setting can also limit how high PS can go. The PS can go only as high as would not cause IPAP to go higher than the Max IPAP setting.

For example, if EPAP is presently 16 and Max IPAP is 20, even if the Max PS setting is 7, PS would be temporarily limited to 4, because the present value of IPAP cannot be higher than the Max IPAP setting. Only when the present value of EPAP is 13 would the PS be able to go as high as 7 without violating the Max IPAP setting.

(09-13-2014 04:47 PM)Galactus Wrote: (09-12-2014 05:51 AM)vsheline Wrote: Regarding, "I don't understand how Max EPAP is unable to reach 18 with a Max PS setting of 7. I thought that if Min EPAP =13 and Max EPAP = 20 with a Max PS of 7 that 13+7=20 and that with a Min PS of 1 that Max IPAP could =20 and Max EPAP could =19 which left both numbers above my original script."

Yes, in your example, EPAP could be as high as 19, but only if PS happens to be 1. EPAP and PS are separately getting raised or lowered in accordance with their separate algorithms, and I think the EPAP algorithm is not allowed to change PS and the PS algorithm is not allowed to change EPAP.

Keep in mind that whenever EPAP is adjusted IPAP is adjusted by the same amount, so that PS will be unchanged.

Let's take the case that Max IPAP is 20, and EPAP has been adjusted to 15, and PS has been adjusted to 4. (EPAP is 15 and IPAP is 19, which is 1 less than Max IPAP.) In that scenario, if your machine senses that a higher EPAP is needed, it can adjust EPAP to 16. (EPAP raises to 16 and IPAP raises to 20, which happens to be Max IPAP.)

One thing I think you have missed, the max on the unit is 25 and not 20. That was part of my consideration in using 20 as being 2 over my 18 as 18 + 7 (PS) = 25 (in my mind) which meant I couldn't get over the script by more than 5 and couldn't be over the machines 25. Because even if EPAP being set to 13 was raised to my script value of 18 and PS =7 then IPAP would still be at 25 which was the machines max. Did I interpret that correctly or miss the boat?

The Max IPAP setting can be set as high as 25, but when the Max IPAP setting is set to 20 then PS cannot be raised if that would result in raising IPAP above the Max IPAP setting.

(09-13-2014 04:47 PM)Galactus Wrote: The one thing I got was IPAP = EPAP + PS. With that in my mind, starting EPAP at 13 and PS at 1 the IPAP = 14. Then I read the line for PS Max and it said "This is the max difference permitted between IPAP & EPAP. So if start EPAP = 14 and 7 = Max difference than 14 + 7 = 21 leaving me 4 under machine max. And in the event the machine raised IPAP to 18 (using what I believed was PS's number) then 18 + 7 (Max allowed difference) = 25 which was the machine max.

When the Max IPAP setting is 20, IPAP will never be allowed to go higher than 20; the machine's max capability of delivering a pressure of 25 has no bearing when the Max IPAP setting is less than 25.

(09-13-2014 04:47 PM)Galactus Wrote: (09-12-2014 05:51 AM)vsheline Wrote: If it so happens that your machine later senses that a still higher EPAP would be beneficial, I think the EPAP could not go to 17, because if EPAP were to be raised any higher, IPAP would also need to be raised by an equal amount, which is not allowed because IPAP is already at its limit.

I believe this changes once you adjust the max to 25 vs 20, but I am not sure.....

Only if the Max IPAP setting is changed to 25 will the IPAP be allowed to go as high as 25.

(09-13-2014 04:47 PM)Galactus Wrote: I've also posted todays numbers as well, so you can see where we are. And when I look at the graph on the right for pressure I don't see IPAP and EPAP moving in tandem, it appears they are moving independently of each other and it make me think somehow I am missing this yet again.

If you look at the points in time at which EPAP did change, every time EPAP changed, both IPAP and EPAP moved in tandem.

(09-13-2014 04:47 PM)Galactus Wrote: