[Pressure] Help me understand EPAP, IPAP and Pressure Support

[OpalRose]

Am I now in the right topic area? I was 'moved', but don't know how to be sure where. I just tried posting and it didn't like where I posted as I didn't have permission.

Kahri,
Yes, this is where your original post was moved.  Did you see the PM I sent you?

It is best to keep your posts here in this thread (as long as you are on the same topic), as it makes it easier to see what advice was given and what you have tried so far.

By all means, if you have a new topic or question, then start a new thread. Most therapy questions should be posted in the Main Forum.

[Kahri]

I'll try and explain pressure support (PS) in my simple minded way. PS is just the difference between inhale pressure and exhale pressure. So if your PS is 4cm than your inhaling at 14cm than your exhaling at 10cm. If your machine is set on auto then pressure will increase and decrease as needed between the minimum EPAP setting and maximum IPAP setting while maintaining a 4cm difference in PS. There's no need for a maximum EPAP since the EPAP always remains 4cm below the IPAP.
The Resmed VAUTO doesn't have variable PS settings.

Hi Walla Walla, 
In the clinical settings on the VAUTO you can indeed change that fixed value of 4. I changed it to 2.8, and have also tested a ps of 7. But if you don't get into the clinical settings, you don't see that flexibility.
I was also told that my pS being 4 and my EPAP being 8 and my Ipap being 14, that PS does not equal the difference between the values of Ipap and Epap. Not on a VAUTO at least. I was told the PS value never changes ONCE SET. (So if it is 'set' at ps7, it will be ps7 throughout the night, remaining fixed while the Ipap and Epap vary up and down), but I am not sure if the IPAP drags the values UP or if the Epap does. Nothing in manuals tells me which one is prime to yank the 'yoked' IPAP and EPAP up or down. 
PS, so far as I can tell so far, is merely a yoke separating Ipap and Epap values so they never come closer to one another than that PS value. Like the rulers the nuns used to have at catholic school dancers to keep the kids shoulders at least one foot apart... you could dance fast or slow, but never reduce that value.
In addition I *think* it would allow these hapless kids at the dance to drift further APART, so IPAP and EPAP could drift apart further than the PS value (which would be the only reason the doc would have a mathematical 'incorrect' PS of 4 with a distance of 6 between IPAP 14 and EPAP 8 with PS 4.
But again, I simply don't know. I think most people have the Respironics systems, for those are the calculations I keep reading about.

[Kahri]

   

Sorry, no pm received. I have a 0 next to the email icon at the top right of this screen. I do now have a posting of my 2nd night's sleep on the doctors settings - I had to get up twice due to discomfort, and the one later into the wee hours of the morning, I had vomited, so the gap is longer as I went for baking soda, water and sitting upright a while. It appears on the graph that as soon as EPAP reaches 8.0, I get sick. It was interesting actually seeing this on Sleepyhead, because telling my doctor I was getting sick didn't seem to sink in:
I need the IPAP value to be able to to 14 (although in the past I was ok at 6)
I need the EPAP value to be 7 to avoid creeping into that vomit zone.
no clue what to do with the PS as long as it does NOT make EPAP go higher than 7:
Please let me know if this graph turns out ok? I tried changing all the settings I read in the link, so it is far more streamlined than what I'm used to seeing.



   

[Walla Walla]

A IPAP of 14cm isn't going to help your stomach problems. I would follow the advice of bonjour

IPAP Max = 7.6
EPAP Min = 4
Pressure Support = 3

Once your stomach gets use to it you can slowly start to raise the EPAP 1cm at a time every few days until you get where you need.

[Sleeprider]

to avoid aerophagia use these settings
IPAP Max 11.0
EPAP min 4.0
PS 4.0
Either turn off ramp or set to auto mode.
These settings will reduce the pressure you can experience. Try this and let us know how you feel. A wedge or incline of the head of your upper body can help with air ingestion.

[Walla Walla]

Bet your really confused about what pressures to use now. 

[mfac11]

I'll try and explain pressure support (PS) in my simple minded way. PS is just the difference between inhale pressure and exhale pressure. So if your PS is 4cm than your inhaling at 14cm than your exhaling at 10cm. If your machine is set on auto then pressure will increase and decrease as needed between the minimum EPAP setting and maximum IPAP setting while maintaining a 4cm difference in PS. There's no need for a maximum EPAP since the EPAP always remains 4cm below the IPAP.
The Resmed VAUTO doesn't have variable PS settings.

Hi Walla Walla, 
In the clinical settings on the VAUTO you can indeed change that fixed value of 4. I changed it to 2.8, and have also tested a ps of 7. But if you don't get into the clinical settings, you don't see that flexibility.
I was also told that my pS being 4 and my EPAP being 8 and my Ipap being 14, that PS does not equal the difference between the values of Ipap and Epap. Not on a VAUTO at least. I was told the PS value never changes ONCE SET. (So if it is 'set' at ps7, it will be ps7 throughout the night, remaining fixed while the Ipap and Epap vary up and down), but I am not sure if the IPAP drags the values UP or if the Epap does. Nothing in manuals tells me which one is prime to yank the 'yoked' IPAP and EPAP up or down. 
PS, so far as I can tell so far, is merely a yoke separating Ipap and Epap values so they never come closer to one another than that PS value. Like the rulers the nuns used to have at catholic school dancers to keep the kids shoulders at least one foot apart... you could dance fast or slow, but never reduce that value.
In addition I *think* it would allow these hapless kids at the dance to drift further APART, so IPAP and EPAP could drift apart further than the PS value (which would be the only reason the doc would have a mathematical 'incorrect' PS of 4 with a distance of 6 between IPAP 14 and EPAP 8 with PS 4.
But again, I simply don't know. I think most people have the Respironics systems, for those are the calculations I keep reading about.

Hi Kahri,

I've seen you post the section in bold above a couple of times, and I think there's a small misunderstanding going on.  

The EPAP setting on your machine (called EPAP Min) is the lowest pressure your machine will blow at you while you are exhaling.  
The IPAP setting on your machine (called IPAP Max) is the highest pressure your machine might blow at you while you are inhaling.
For VAUTO mode, the PS setting has no direct connection to either of those settings.  If you are trying to make the equation of EPAP Min = IPAP Max - PS work, it shouldn't.  That's not what the PS setting is for in this mode.

Instead, your machine will start the night blowing at a EPAP pressure of EPAP Min.  For the same breath, when you inhale, the machine will blow at you with a pressure (IPAP) of EPAP Min + PS.  If, as the night progresses, the machine decides you need more pressure, it will increase both EPAP and IPAP by the same amount so their difference stays equal to PS.  The machine can continue to raise your pressures (if it sees a need for it) until the IPAP Pressure gets to IPAP Max.  At this point, the EPAP Pressure will be at IPAP Max - PS.  If the machine decides you need less pressure, it will lower your pressures in the same manner, not going lower than when you started the night. 

I hope this helps.  If I've confused you more, I apologize.  If I've made a mistake, I hope someone else will correct me.

Mike

[Gideon]

Here are the words right out of the ResMed VAuto clinical manual
The inspiratory positive airway pressure (IPAP, or the sum of EPAP and the pressure support level) assists inspiration.

Thus per ResMed IPAP = EPAP + PS

[mesenteria]

You are in auto titrate mode, so your pressures, inspiration and exhalation, are both variable.  The machine adjusts them as it feels is best for you, but always within the high and low limits.  You know what your limits are, but not what the EPAP and IPAP pressures will be at any one time unless you query the machine and read what its current settings are.

Regardless of what the IPAP is at moment X during the night, your EPAP will always be 4 less.  That's what your pressure support setting is, 4 less than whatever the current IPAP pressure is.

Not to belabor this point, but suppose you enter sleep at 2200 hrs, and your IPAP is 12.  With each exhalation, the machine will slow the fan to reduce its pressure by 4 cm H2O.

Near 2245 hrs, the machine senses a flow limitation and figures it should bump up your pressure to 12.5 cm.  It automatically raises your EPAP to 4 less than that, which now becomes 8.5 cm. (I'm not sure if the machine can raise pressures by only half a cm, but it's just an example...)

This goes on all night.  You can adjust the minima and mixima yourself if you wish, and you can adjust the EPR from "off" to 1 to whatever the maximum PS setting the machine is designed to provide.  But, when it's in auto mode, the machine is free to adjust its pressures within the limits you stipulate.  If you set PS, it will automatically back off the pressure with each exhalation, and reduce the pressure in keeping with the setting you programme for EPR.

[Kahri]

to avoid aerophagia use these settings
IPAP Max 11.0
EPAP min 4.0
PS 4.0
Either turn off ramp or set to auto mode.
These settings will reduce the pressure you can experience.  Try this and let us know how you feel.  A wedge or incline of the head of your upper body can help with air ingestion.

I agree inclines help, and tried sleeping in a  Brazilian hammock for about 6 months. Also slept in a recliner for some months. Being post-breast-cancer, I can only sleep on one side. Apnea worst on back. So am leery of bending my spine one way 8 (if I ever can get 8) hours a night.
Love the hammock, but tough to explain to surgeons that you can't sleep in a bed. So, seeking solutions that allow me  flat side sleeping.
All that being said, those Sleep Number beds seem tempting.

Fear all this machinery will make me never get me cully well again, for once I do get set, my body will stop trying to correct on its own.

But for now, I need rest anyway I can get it