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Trying to Understand EPap, IPap & RS
#1
I'm trying to figure out how to set my machine for best results.
Best so far:
VAuto
Max IPap=22
Min EPap=14
PS=2
Results -- 4.7 hours at 4.63AHI
EPap-- Min-15.36, Med=16.42, 95%=17.44 and Max=17.82
IPap--Min=16, Med=16.12, 95%=16.8 and Max17.88
Hypopnea = 1.26
OA=2.95
Unclassified Apnea=0
CA = 0.42
Mask = Quattro Air Pretty tight

My questions -- If the EPap is tied to PS and starts above Minimum IPap, why doesn't the pressure continue to build until it stops the apneas? Like, why didn't it go to 18, 19 or 20 instead of only 17.82. I guess I don't understand the relationship between EPap, IPap, PS and how they work together to minimize apneas.

Any help would be much appreciated.
Bob






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#2
IPAP should be greater than EPAP by the PS. IPAP=EPAP+PS. You inhale with a greater pressure than you exhale against. The upper limit of IPAP is Max IPAP. The lower limit on EPAP is Min EPAP.

ergo: This statement is incorrect: " If the EPap is tied to PS and starts above Minimum IPap..."

What you are really asking is why doesn't your machine run up to 22 cm-H2O IPAP to further reduce your AHI. It's involved in the rather complicated scoring algorithm; and how pressure changes in response to flow limitation, snoring, Obstructive Apnea, Hypoapneas and Central Apneas. I can think of at least one reason the pressure does not reach max IPAP -- central apneas can be induced by pressure.

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#3
la la la............ The ipap is connected to the epap. The epap is connected to the cpap. The cpap is connected to the vpap. and my pap is connected to my mom........ (So ok. the last line doesn't work. Oh well.)
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#4
Oh, I don't know. The fact that mom was connected to pap worked for me.
It looks to me like we set max EPap and min IPap and that the machine operates between these based on it's sense of what's necessary. I guess what I'm trying to get a handle on is what criteria do I use to select PS?
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#5
I think i've got it wrong. It's max IPap and min EPap that we set and then the machine operates between these as needed. Still, what is the criteria for selecting PS.

Thanks for the conversation.
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#6
PS is a comfort thing more than anything else. It just allows you to exhale at a bit lower rate. I have mine set to be 3 points less than the current supplied pressure. So if my machine is trucking along at 12, the expiration will be at 9. I think if it were set to close together you might not really see much difference at all, and if it were set too far apart you might actually be aware of the "kick" on resuming ipap time. But I don't know. I just turned mine on and it seems to be happy with me so I'm happy with it.
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#7
(05-18-2014, 07:59 PM)BiBob Wrote: what is the criteria for selecting PS?

Hi BiBob,

Initially, Pressure Support (PS) is most often set for comfort. Later, it may be optimized to improve sleep quality.

At the tail end of an overnight titration, after an adequate pressure has been identified which largely prevents apneas and hypopneas, the technician may explore the effect of increasing PS in order to further reduce Respiratory Effort-Related Arousal (RERA) events, which are arousals from sleep caused by respiratory effort but not accompanied by apneas or hypopneas. The number of RERA events per hr is not included in the AHI.

Sometimes excessive daytime sleepiness continues to be a problem even after the AHI with CPAP treatment looks fine, and sometimes RERAs may be the reason; RERAs may be preventing deep restorative sleep, and increasing the PS may help this.

But too high of a PS can also cause problems, so higher PS is not necessarily better and for some patients may lead to excessive Central Apneas (more than 5 per hr and outnumbering obstructive events).

I don't think central apneas are more alarming than obstructive apneas. (I think a central event if shorter would be preferable to a longer obstructive event.)

The PS will also have an influence on your blood Oxygen level (SpO2). If the SpO2 is too low or too high it can cause problems.

So I recommend buying a recording Pulse Oximeter. A great target range for SpO2 is 96% to 94%, or perhaps a little lower while sleeping. If the average SpO2 is below 90%, increasing the PS will tend to raise SpO2. If the average PS is above 96%, decreasing PS will tend to lower SpO2.

Take care,
--- Vaughn
Membership in the Advisory Member group should not be understood as in any way implying medical expertise or qualification for advising Sleep Apnea patients concerning their treatment. The Advisory Member group provides advice and suggestions to Apnea Board administrators and staff on matters concerning Apnea Board operation and administrative policies - not on matters concerning treatment for Sleep Apnea. I think it is now too late to change the name of the group but I think Voting Member group would perhaps have been a more descriptive name for the group.
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#8
Vaughn,
Thank you. I have a Oximeter that clips onto my finger but I assume you're referring to something that plug into my s9. Is that correct?
I'll look it up on the internet.
Thanks,
Bob
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#9
With your pressures set to Max IPap=22, Min EPap=14, & PS=2 here's how it's working.
At the beginning of the night you start out with the exhale (EPap) set at 14 and the inhale (in this case EPap+PS) at 16.
When the machine sees what it thinks is an event beginning, it raises the EPap slowly until it senses that it has effectively stopped the event(s) or it reaches the max IPap (22cmH2O).
It then starts slowly lowering the pressure back toward the Min EPap until it either reaches Min EPap (14cmH2O in your case) or it sees another event happening.
And it starts the cycle all over again.

If you start with your EPap set too low it takes too long for the machine to respond to an event and some events slip by before the machine has time to fully correct them.

Given your numbers I'd raise the Min EPap .4 or .6 cm at a time and watch it for a few days and see if it helps the Obstructives and the Hypopneas without raising the CA's. If it does, then you can continue raising it a little at the time until you reach a happy medium with your AHI. If a lot CA events start showing up you want to stop raising your pressure because more pressure can cause CA events.
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#10
Thank you so much. I'll give it a shot. Appreciate the help a lot. The forum is really better than anyplace else in getting help and finding out just how to make all this work.

Thanks Bama R,
Bob
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