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Setting BiLevel Pressure Support S9 VPAP Auto

Posted: Tue Jul 03, 2012 7:31 am
by squid13
What determines what pressure support number you use. I know it's IPAP minus EPAP. Say that is 4 but could you use a 3 or a 2 and if that is true what effect would it have.

Re: Setting BiLevel Pressure Support.

Posted: Tue Jul 03, 2012 8:56 am
by jnk
squid13 wrote:What determines what pressure support number you use. I know it's IPAP minus EPAP. Say that is 4 but could you use a 3 or a 2 and if that is true what effect would it have.
The official answer (although I am nothing official, myself) is that the difference between the prescribed IPAP and the prescribed EPAP is the prescribed PS, as I understand it. The nice thing about your machine is that it can be run as an auto-bilevel while still keeping the PS, the distance between EPAP and IPAP, constant at all times.

Four is the most common PS, since recent AASM suggestions suggest starting at 4 cm for PS during a bilevel titration. A prescription of less than 4 PS these days would be considered nonstandard, I believe.

As far as what effect a different PS would have on a particular person, that would depend on the reasons for the bilevel prescription in the first place for that particular patient.

If you can't help but tinker with it , you might want to watch both your AHI AND your O2, using an overnight oximeter. But I would never suggest that anyone tinker with that without having his doc on board with his doing so.

But hey, that's just me.

Re: Setting BiLevel Pressure Support in S9 VPAP Auto

Posted: Tue Jul 03, 2012 9:05 am
by squid13
I know the ResMed Clinical setup says adjust for patient comfort. So say if you set it for 10 EPAP and 13 IPAP you set it at 3.

Re: Setting BiLevel Pressure Support.

Posted: Tue Jul 03, 2012 9:17 am
by Pugsy
When I got my bilevel machines I tried to find an explanation as to which pressure support setting might be advisable in what situation and never could find anything. Setting it with a very narrow PS (like 2) sort of makes it work like the Autoset with EPR of 2. While of course not exactly like it because the timing is a bit different it isn't hugely different.
I opted for PS of 4 mainly for comfort and I rest well with it and that seemed to be the most common setting, reports look great so I don't know what I would expect to improve upon by changing PS.
I do suspect that if someone had some bad aerophagia symptoms that perhaps a wider PS might help with that problem but I never really found any documented evidence of it nor any other specific information as to what PS at various settings might do.
SWS or JohnBFisher might have a better grasp on the "whys" because I certainly never could wrap my head around it.

Me....I just picked an average used number and tried it and liked it and felt great. Real scientific heh?

Re: Setting BiLevel Pressure Support.

Posted: Tue Jul 03, 2012 9:41 am
by squid13
Mine is set at EPAP 10 and IPAP 14 with PS of 4. I know you can tweak your pressures up or down to what ever is the best for you but just trying to just understand the PS when doing so. I didn't sleep well when I had my BiPap titration and they came up with 10 and 14. I also read somewhere where 10 and 14 is an average setting.

Re: Setting BiLevel Pressure Support.

Posted: Tue Jul 03, 2012 9:52 am
by jnk
4.3.1.6 The recommended minimum IPAP-EPAP differential is 4 cm H2O and the recommended maximum IPAP-EPAP differential is 10 cm H2O (Consensus).
This recommendation is based on consensus agreement by the PAP Titration Task Force and Guideline-Level evidence . . . for the minimum IPAP-EPAP differential in adult patients.
http://www.aasmnet.org/Resources/clinic ... 040210.pdf

Re: Setting BiLevel Pressure Support.

Posted: Tue Jul 03, 2012 9:58 am
by squid13
jnk thanks for that article, I'll sit down and read it after lunch.

Re: Setting BiLevel Pressure Support.

Posted: Tue Jul 03, 2012 10:05 am
by robysue
On the Resmed Auto VPAPs, that PS is going to be the constant difference IPAP and EPAP. As the machine adjusts the pressure up and down, the IPAP and EPAP will both be adjusted at the same time and by the same amount.

It may help to consider a few examples: Let's say that we have Min EPE = 8 and MAX IPAP = 16. Now lets consider what happens with different PS levels:

With PS = 2, we have the following ranges 8 <= EPAP <= 14 and 10 <= IPAP <= 16
With PS = 3, we have the following ranges 8 <= EPAP <= 13 and 11 <= IPAP <= 16
With PS = 4, we have the following ranges 8 <= EPAP <= 12 and 12 <= IPAP <= 16
With PS = 5, we have the following ranges 8 <= EPAP <= 11 and 13 <= IPAP <= 16
With PS = 6, we have the following ranges 8 <= EPAP <= 10 and 14 <= IPAP <= 16

So in "picking" a PS, what's important?

Well comfort is one consideration. The basic premise of bi-level is that providing a sufficiently large enough drop in pressure on exhale should make the machine more comfortable to use. But if the drop is too large, that can cause comfort (and leak) problems for some individuals. Really large PS settings may leave you feeling as machine is blasting air down you gut with every inhalation, which may not be very sleep inducing.

But therapy needs are also important: That EPAP needs to be able to increase far enough to deal with nasty clusters of OAs and significant snoring during the times when you are running at max pressure. In other words, the PS needs to be set so that Max EPAP = Max IPAP - PS should be at least 1-2cm above your 95% EPAP. And the initial IPAP = Min EPAP + PS needs to be high enough for you to not feel like you are air-starved. And that initial IPAP should be high enough to deal with most of you flow limitations and hypopneas. In other words, Min EPAP + PS should probably be within 2-4cm of your 95% IPAP.

Re: Setting BiLevel Pressure Support.

Posted: Tue Jul 03, 2012 10:06 am
by RandyJ
I found this post by restedgal helpful when I was setting my machine. She advocates using the highest PS setting:

viewtopic.php?f=1&t=45059&p=450776&hili ... rt#p450776

I think this is so IPAP has more freedom to range in responding to events without necessarily causing EPAP to rise as well.

Re: Setting BiLevel Pressure Support.

Posted: Tue Jul 03, 2012 10:15 am
by Pugsy
RandyJ wrote:I found this post by restedgal helpful when I was setting my machine. She advocates using the highest PS setting:
I believe she was using a Respironics BiPap at the time she wrote that.
Respironics BiPap machines allows for a roaming pressure support...so it can vary up to the 8 cm pressure support. This is totally different way of working than the ResMed bilevel machines. So she was really leaving the PS wide open to range from 2 cm to 8 cm as the machine deemed necessary.

ResMed machines have a fixed pressure support and there is no varying or roaming about. EPAP and IPAP are tied to each other by the pressure support which won't/can't vary.

This roaming vs fixed pressure support raises another question which I never found an answer to..
When is one method preferable over another?

Re: Setting BiLevel Pressure Support.

Posted: Tue Jul 03, 2012 10:33 am
by robysue
Pugsy wrote: Respironics BiPap machines allows for a roaming pressure support...so it can vary up to the 8 cm pressure support. This is totally different way of working than the ResMed bilevel machines. So she was really leaving the PS wide open to range from 2 cm to 8 cm as the machine deemed necessary.

ResMed machines have a fixed pressure support and there is no varying or roaming about. EPAP and IPAP are tied to each other by the pressure support which won't/can't vary.

This roaming vs fixed pressure support raises another question which I never found an answer to..
When is one method preferable over another?
I think the anwser to that is "It depends."

For people like you who appreciate a 4cm drop in pressure while they're awake and who are not troubled by aerophagia when the EPAP is high, the fixed PS is probably more comfortable.

For people like me who don't mind starting out with IPAP = EPAP + 2 and who have problems with aerophagia when the EPAP is near its max, the roaming PS will maximize the time spent with EPAP at or near the Min EPAP setting and hence be more comfortable.

For most people? My guess is that it probably doesn't much matter.

Re: Setting BiLevel Pressure Support.

Posted: Tue Jul 03, 2012 11:17 am
by jnk
The variable PS would appeal to me IF there was a way to set minimum PS.

For patients with OHS issues, or other hypoventilation issues, 2 cm ain't gonna cut it, IMO as a patient.

The issue, also merely IMO, is not so much the brand of machine used but that RTs don't know the difference between brands well enough and too often set up machines wrong when attempting to set up autobilevels to run in auto mode. I have no evidence of that beyond the anecdotal evidence of what I've experienced, read, and heard from the mouths of RTs, though.

Discussions of setting the PS in a ResMed autobilevel are moot, though, unless we know for sure a poster's machine is in VAUTO mode with some room to vary. I believe that autobilevel machines are most often handed out set up to run in plain old bilevel (S) mode, or are programmed with min EPAP set at the exact prescribed EPAP and the max IPAP set at the exact prescribed IPAP and therefore do not function as autos at all, even though the doc and RT may not be aware that is the case.

Those are merely my opinions about my personal assumptions.

Re: Setting BiLevel Pressure Support.

Posted: Tue Jul 03, 2012 11:29 am
by squid13
robysue wrote:It may help to consider a few examples: Let's say that we have Min EPE = 8 and MAX IPAP = 16. Now lets consider what happens with different PS levels:

With PS = 2, we have the following ranges 8 <= EPAP <= 14 and 10 <= IPAP <= 16
With PS = 3, we have the following ranges 8 <= EPAP <= 13 and 11 <= IPAP <= 16
With PS = 4, we have the following ranges 8 <= EPAP <= 12 and 12 <= IPAP <= 16
With PS = 5, we have the following ranges 8 <= EPAP <= 11 and 13 <= IPAP <= 16
With PS = 6, we have the following ranges 8 <= EPAP <= 10 and 14 <= IPAP <= 16
robysue I must be having a senor moment cause this chart confuses me. Is that 8 below equals EPAP,below equals 14 and 10, below equals IPAP below equals 16

Re: Setting BiLevel Pressure Support.

Posted: Tue Jul 03, 2012 12:05 pm
by GumbyCT
squid13 wrote:
robysue wrote:It may help to consider a few examples: Let's say that we have Min EPE = 8 and MAX IPAP = 16. Now lets consider what happens with different PS levels:

With PS = 2, we have the following ranges 8 <= EPAP <= 14 and 10 <= IPAP <= 16
With PS = 3, we have the following ranges 8 <= EPAP <= 13 and 11 <= IPAP <= 16
With PS = 4, we have the following ranges 8 <= EPAP <= 12 and 12 <= IPAP <= 16
With PS = 5, we have the following ranges 8 <= EPAP <= 11 and 13 <= IPAP <= 16
With PS = 6, we have the following ranges 8 <= EPAP <= 10 and 14 <= IPAP <= 16
robysue I must be having a senor moment cause this chart confuses me. Is that 8 below equals EPAP,below equals 14 and 10, below equals IPAP below equals 16
Try this
8 <= EPAP <= 14
and
10 <= IPAP <= 16

Re: Setting BiLevel Pressure Support.

Posted: Tue Jul 03, 2012 12:12 pm
by RandyJ
Pugsy wrote: I believe she was using a Respironics BiPap at the time she wrote that.
Respironics BiPap machines allows for a roaming pressure support...so it can vary up to the 8 cm pressure support. This is totally different way of working than the ResMed bilevel machines. So she was really leaving the PS wide open to range from 2 cm to 8 cm as the machine deemed necessary.

ResMed machines have a fixed pressure support and there is no varying or roaming about. EPAP and IPAP are tied to each other by the pressure support which won't/can't vary.

Oops... missed that part.... maybe the OP could add "Resmed S9 VPAP" to the thread title....