Is there a minimum difference between IPAP and EPAP pressure

I don't know. I'm not a doctor, but I spent a couple of hours on the Internet reading up on machines and understood pretty well how they work. Indeed, I understood just from reading the manual I downloaded from the Internet that EPR decreased pressure by anywhere from 1-3 cmH20. It didn't seem to me that ResMed was hiding anything, at least from providers (as a mere patient, I was not supposed to have the full manual, of course). I would hope that any doctor who makes his living treating sleep disorders would be capable and interested enough to do the same modest research that I did.

The point is that docs will never write prescriptions by saying: "If patient uses brand x, the presribed pressure is A, if patient uses brand y, pressure should be B, and if . . .

Patients have time to educate themselves on the intricacies of their conditions. Docs deal with too much to have time to learn about all approaches for all conditions from month to month. Technically, with PAP, it is supposed to be the RT at the DME who knows the subtle differences of the machines. And we've all seen how they are at that, with few exceptions.

Remember, once the doc diagnoses the condition and scribbles on the pad, his job is consideres done, unless patient asks for more help. In many places, anyway. Not ideal. But in reality, that is the situation for many people. I doubt most DME drones even realize there is a difference betwen brands in how expiratory relief works.

old dude wrote:I know that this might be ordinarily called "pressure support" but since I use my Auto BiPAP machine in the fixed Bilevel mode I wasn't certain that PS would be the correct term. Anyway, I've been using pressures of 11/7 with good results, AHI normally ~ 1.0 or less. But my snoring seems to be creeping up a bit so I thought I'd try bumping my EPAP pressure up to 7.5 to see if that might help.

Is 3.5 cm enough of a spread between IPAP and EPAP, or does it even matter?

Thanks all.

"pressure support" is what they call the difference between epap and ipap, whether epap, ipap,or ps vary or not, and the minimum difference is 0.

jnk wrote: As a general rule, IPAP is what addresses snores; EPAP is mostly about apneas, as I understand it. IPAP is for most everything else. But there are exceptions to every such rule of thumb, of course.

While the AASM titration guidelines specify increasing IPAP in the presence of snoring, it's interesting to note that with the the PR BiPAP Auto's Auto algorithm, only the EPAP is increased when the machine detects snoring if IPAP - EPAP > min PS setting.

The Resmed VPAP, however increases both IPAP and EPAP at the same time because the Resmed VPAP always increases the IPAP and EPAP together in response to events, flow limitations, and snoring.

I think this paper supports some of Jeff's points:
http://journal.publications.chestnet.or ... id=1084615

That paper is dated August 2006 and refers to auto cpap and FL detection in the algorithm and really doesn't address bilevel fixed pressures that I could find anywhere in the paper. Apples and oranges comparison and an old comparison at that. Algorithms have changed significantly with the identification of central apneas being written into the algorithm specifically.

OP in this thread is using fixed bilevel pressures and not auto adjusting bilevel pressures.

APAP with a minimum pressure is not the same thing as a fixed bilevel pressure mode EPAP with the maximum APAP being sort of like IPAP.
Minimum pressure in APAP might sort of work like EPAP minimum in that it needs to be high enough to do a decent job stenting the airway open in the first place....prevention vs fixing after the fact.

this is a really good topic... for those of us on straight Bi-level settings...

I started out with 21 IPAP / 15 EPAP.

After almost 2 years of use, I've determined that 14.2 is about the absolute minimum EPAP setting that I can have before major obstructions erupt and my AHI skyrockets.

But over that same period of time, I've been slowly dropping the IPAP setting & I'm currently at 18.4 IPAP.

AHI is below 1.0 almost every night and most nights its below 0.5.

So now I'm beginning to wonder if there is an absolute minimum difference needed between EPAP and IPAP settings when on straight bi-level settings.

Dave

Denial Dave wrote:this is a really good topic... for those of us on straight Bi-level settings...

I started out with 21 IPAP / 15 EPAP.

After almost 2 years of use, I've determined that 14.2 is about the absolute minimum EPAP setting that I can have before major obstructions erupt and my AHI skyrockets.

But over that same period of time, I've been slowly dropping the IPAP setting & I'm currently at 18.4 IPAP.

AHI is below 1.0 almost every night and most nights its below 0.5.

So now I'm beginning to wonder if there is an absolute minimum difference needed between EPAP and IPAP settings when on straight bi-level settings.

Dave

DD, as Pugsy points out in her post directly above I too am on fixed bilevel settings. You may have been aware of this.

What I'm beginning to wonder now is if Bi-Flex on the PRS1 machine is analogous to EPR on the S9 machine. By that I mean it seems that EPR of say 3 on the ResMed machine seems to actually drop the EPAP 3 cm from the IPAP. So if one built in a PS of say 4, wouldn't that be a total of 7? And is that also true of BiFlex on the System One machine?

FWIW back when I was shopping for a travel machine I was told several times by CPAP.com that EPR bore no relationship at all to true Bi-Level; they were said to be totally different things and would have no similar effect at all.

old dude wrote:What I'm beginning to wonder now is if Bi-Flex on the PRS1 machine is analogous to EPR on the S9 machine. By that I mean it seems that EPR of say 3 on the ResMed machine seems to actually drop the EPAP 3 cm from the IPAP. So if one built in a PS of say 4, wouldn't that be a total of 7? And is that also true of BiFlex on the System One machine?

You are assuming that each biflex setting equals 1 cm reduction but that's not the case. I just looked at the manuals for the BiPap and all it says is "small amount" of relief for a setting of 1. It never mentions a per cm reduction that I could find.
With the APAP machines they say "up to 2 cm reduction at maximum setting" and remember that the amount of reduction is going to be flow based meaning how much it reduces is going to depend on the force of your own breathing.
I didn't see any "up to xx cm reduction" in the manuals that I have and it clearly doesn't mention any set cm reduction.

I don't think that PS of 4 and BiFlex of 3 is going to work like PS of 7...and drop that EPAP way down.

You could try turning BiFlex off though to see if it makes any difference either in comfort and/or your snores. It might or might not. In theory I supposed that it might but I doubt it makes much of a difference in real life.
BiFlex is more about the timing of the reduction than it is the actual amount of reduction.

Pugsy wrote:

old dude wrote:What I'm beginning to wonder now is if Bi-Flex on the PRS1 machine is analogous to EPR on the S9 machine. By that I mean it seems that EPR of say 3 on the ResMed machine seems to actually drop the EPAP 3 cm from the IPAP. So if one built in a PS of say 4, wouldn't that be a total of 7? And is that also true of BiFlex on the System One machine?

You are assuming that each biflex setting equals 1 cm reduction but that's not the case. I just looked at the manuals for the BiPap and all it says is "small amount" of relief for a setting of 1. It never mentions a per cm reduction that I could find.
With the APAP machines they say "up to 2 cm reduction at maximum setting" and remember that the amount of reduction is going to be flow based meaning how much it reduces is going to depend on the force of your own breathing.
I didn't see any "up to xx cm reduction" in the manuals that I have and it clearly doesn't mention any set cm reduction.

I don't think that PS of 4 and BiFlex of 3 is going to work like PS of 7...and drop that EPAP way down.

You could try turning BiFlex off though to see if it makes any difference either in comfort and/or your snores. It might or might not. In theory I supposed that it might but I doubt it makes much of a difference in real life.
BiFlex is more about the timing of the reduction than it is the actual amount of reduction.

You know Pugsy (and BTW I appreciate the explanation) I probably could experiment a bit with BiFlex but I've had mine set on "3" since I first started and it's fair to say I've become used to it now being set that way. Absent any problems that could be directly attributable to the BiFlex setting I'll likely just leave well enough alone since I'm acclimated to it. Thinking back on about 16 months ago when I first started, I remember an initial feeling that I was breathing out of sync with the machine somehow. It's hard to explain, but it was like the machine wanted me to breathe either before or after I felt like I wanted to. One of us adapted pretty quickly though and that feeling didn't seem to last long.

Given my general level of anxiety and a somewhat fragile sleep protocol I've learned that if something is working OK I try not to change it. If there's a problem I will experiment though.

old dude wrote:Given my general level of anxiety and a somewhat fragile sleep protocol I've learned that if something is working OK I try not to change it. If there's a problem I will experiment though.

Probably wise to go the "if it ain't broke don't fix it" road.
Care to see what happened to me when I turned off AFlex after using it for probably 2 plus years?
viewtopic.php?f=1&t=67883&p=631376&hili ... mb#p631376

In regards to your snores...what you might do is switch over to auto mode but severely limit the IPAP max to 1 cm above your fixed IPAP now. If the machine thinks the snores needs fixing then the pressure will increase. If it doesn't think the snores need fixing it won't increase. Like external vibrations from something....my machine never tried to fix my Pug dog snores despite them showing up as pretty much solid line of snores for maybe a couple of hours. Never tried to increase the pressure at all. That was one of the reasons I never paid any attention to them before I figured out what they were from. I was assuming some sort of external vibration from maybe the hose or something.

Pugsy wrote:

old dude wrote:Given my general level of anxiety and a somewhat fragile sleep protocol I've learned that if something is working OK I try not to change it. If there's a problem I will experiment though.

Probably wise to go the "if it ain't broke don't fix it" road.
Care to see what happened to me when I turned off AFlex after using it for probably 2 plus years?
viewtopic.php?f=1&t=67883&p=631376&hili ... mb#p631376

In regards to your snores...what you might do is switch over to auto mode but severely limit the IPAP max to 1 cm above your fixed IPAP now. If the machine thinks the snores needs fixing then the pressure will increase. If it doesn't think the snores need fixing it won't increase. Like external vibrations from something....my machine never tried to fix my Pug dog snores despite them showing up as pretty much solid line of snores for maybe a couple of hours. Never tried to increase the pressure at all. That was one of the reasons I never paid any attention to them before I figured out what they were from. I was assuming some sort of external vibration from maybe the hose or something.

You must be reading my mind. I have indeed thought about taking another shot (later this summer when travel is over) at setting my machine on Auto mode as it was intended to be used in most cases. The reason I'm on fixed BiLevel now is that back before I started doing my own pressures my doc did indeed give his RT instructions to have my DME switch my machine over to auto, and the results were disastrous. The DME didn't like the doc's RT's instructions, so they argued back and forth a bit, but the result was that while my EPAP never went over 11.9 my IPAP stuck on 5.0 for the entire time and wouldn't budge. For those two nights my AHI was over 7. I think what they did was to screw up the settings on PS and minimum IPAP or EPAP. Rather than continue to fool with it I just set it back to fixed BiLevel and forgot about it.

Like I said, when things settle down a little this summer I'll post for some help with proper setting of the Auto mode and see if I can get the machine operating properly. It seems to only make sense that I should use it that way since all 3 of my machines are 760Ps and I hate wasting the Auto feature.

While I am thinking about it here would be a possible auto setting for you to try with your 760 machine.

Since you are currently using fixed mode 11 IPAP and 7 EPAP that means you are using 4 cm PS.
To test auto mode to see if it want to respond to the snores
Minimum EPAP set to 7
PS minimum set to 4 and PS maximum set to 4
Maximum IPAP set to 12.
Tiny auto range of 1 cm would be the result with PS being fixed like it is now.
If the machine wants to try to fix the snores you will see an increase in the pressure line at the same time the snores are present. Now it might still go up and down a bit due to FLs or something else but for purposes of evaluating the snores themselves...you would have to look at the time frame where the snores are showing up.

Pugsy wrote:While I am thinking about it here would be a possible auto setting for you to try with your 760 machine.

Since you are currently using fixed mode 11 IPAP and 7 EPAP that means you are using 4 cm PS.
To test auto mode to see if it want to respond to the snores
Minimum EPAP set to 7
PS minimum set to 4 and PS maximum set to 4
Maximum IPAP set to 12.
Tiny auto range of 1 cm would be the result with PS being fixed like it is now.
If the machine wants to try to fix the snores you will see an increase in the pressure line at the same time the snores are present. Now it might still go up and down a bit due to FLs or something else but for purposes of evaluating the snores themselves...you would have to look at the time frame where the snores are showing up.

Thank you Pugsy.

I may wait a few weeks to delve into this but I'll definitely give this a try and report in when I do.