Which comes first ???

[BML]

Hello everyone,

Below is a graph of last night's activity, it is not one of my better nights. However, it does bring up an interesting question: which comes first?

When I look at the graphs, my leak appears to increase AFTER the pressure has gone up. In other words, the pressure increase is causing the leak not compensating for it. Now, the pressure goes up when there are apneas. I have understood from previous posts that the Respironics BiPAP does not immediately respond to apneas: it doesn't stop them, it prevents them from occurring later by increasing pressure.. right? So, if I have understood this correctly, from my graphs I would conclude that the system has upped the pressure, thereby increasing the leak rate and triggering an apnea? Should I decrease my EPAP? Somehow that doesn't make sense. All comments, suggestions, corrections welcome!

I have a leak rate of 40 on average and have had great nights with an AHI < 5 and time in apnea < 10 minutes/day.

[rested gal]

It looks like most of the pressure raises are due to EPAP having to go up and consequently pushing IPAP up in order to maintain that minimum 2 cm separation between the two pressures that the Respironics BiPAP Auto must maintain when being used in auto bilevel mode.

An awful lot of "obstructive apneas" are still sneaking through. EPAP is the pressure that is supposed to prevent most obstructive apneas.

So, if that were my data, I'd raise the min EPAP some more.

While I was at it, I'd also raise the max IPAP since the present ceiling you've set for max IPAP is being hit too much, imho. I think it's good to have a margin of pressure that's never ever used up there. Otherwise, you can't know how much pressure really would have been needed.

It doesn't look to me as if you're having any significant leak problems. Just looks (to me) as if the EPAP is not set high enough.
But I'm not a doctor!

If it were me, I'd probably try these pressure settings for a few days:

Max IPAP 20.0
Min EPAP 12.0 (or 11)
Max Press Sup 8.0

Bi-Flex Setting 3 (or whatever "flex" setting felt smooth.)
If I didn't turn on "bi-flex", then I'd set the "Rise Comfort" on 3 (or whatever "rise" setting felt smooth.)

_____________________________________

My thoughts about EPAP setting on a bilevel machine (and min EPAP on the BiPAP Auto.)

November 2007 - EPAP is for more than just comfort exhaling.
viewtopic.php?p=227068#p227068

December 2007 - my understanding of how a bipap titration is done.
viewtopic.php?p=231786#p231786

May 2008 - discussion with RonS about importance of EPAP setting.
viewtopic.php?p=265020#p265020

[Wulfman]

You forgot three other elements/events that cause pressure increases.......leaks, snores and flow limitations.

Did you have "prescribed" EPAP and IPAP settings for your therapy (from a titration)?

Are you sure you're not leaking air out of your mouth?

Den

[BML]

Hi RestedGal,

I also considered increasing my min EPAP but look at this:



Why do my OA's increase in number with my increases in pressure? There are a lot more at an EPAP=13 compared to lower pressures and somehow I manage to spend 40% of my night at an EPAP=9 with the lowest AHI for an EPAP setting. I find that puzzling. In your experience, what do you think causes this?

I am a bit more nervous about increasing my MAX IPAP for now. My hypopnea AI is usually 1 or less. 90% of the time IPAP is at 14.5 or less according to the last page of the report (for the last 7 days). I think I would rather start working on my OA's and get those low to greatly improve my AHI and my time in apnea which fluctuates a lot and is still too high I think.

Bernard

[BML]

Den,

I have had the same average leak from day 1 and have seen my AHI improve from 68 to an average AHI=4-5. I don't think leaks are a problem. If I was leaking air from my mouth I think I would notice (I did back in the beginning a few months ago). I don't know what the VS means. Titrated EPAP=5 IPAP=15 relief of 4 on BiPAP Auto.

Bernard

[Pugsy]

VS is Vibratory Snores.

Someone else will need to explain the mechanics of how/why the machine records snores and how it relates to your data.

[Wulfman]

Den,

I have had the same average leak from day 1 and have seen my AHI improve from 68 to an average AHI=4-5. I don't think leaks are a problem. If I was leaking air from my mouth I think I would notice (I did back in the beginning a few months ago). I don't know what the VS means. Titrated EPAP=5 IPAP=15 relief of 4 on BiPAP Auto.

Bernard

Vibratory Snore

Well, I was wondering about the nature of the leak spikes which seem to be occurring at the beginning of your events (OAs and Snores). If mouth leaks are causing a pressure loss in your airway "circuit", then the OAs and Snores could increase.....which is what they seem to be doing.

Sounds like they were way off on your titrated pressures.......

Den

[BML]

Well, I was wondering about the nature of the leak spikes which seem to be occurring at the beginning of your events (OAs and Snores). If mouth leaks are causing a pressure loss in your airway "circuit", then the OAs and Snores could increase.....which is what they seem to be doing.

Again, I have had the same leak level (more or less) for as long as i have been able to check data. I move a lot at night from back to side and I think there are relatively few spikes considering that tossing in bed. I don't know that I can do much to improve that short of duck taping myself to the mattress to eliminate movement.

Sounds like they were way off on your titrated pressures.......

Den

Well, , are you surprised. They moved it from EPAP=5 to EPAP=8 when I told them it was hard to breathe.... then I moved it to 9. I don't know how they came up with the numbers.. maybe they thought the BiPAP Auto would do all the work.

Bernard

[rested gal]

Why do my OA's increase in number with my increases in pressure?

Bernard, I don't know. I never bother to even glance at the "Summary of Daily Events Per Hour" charts from the Encore report. ozij or someone else more "math" inclined than I am can probably understand the "why" of it, but I don't even try to make sense of that particular chart on my reports.

The thought that occurs to me is... It may not be that the increases in pressure are actually causing an increase in Obstructive Apneas.

The apneas you see listed at certain pressures might be ones that sneaked through during a time when you were on your back and/or were in REM -- two scenarios when apneas are most apt to hit and when more pressure is usually required. Those are scenarios which are revealed only when a person is hooked up to PSG equipment. Our treatment machines can't tell what position we're in or what sleep stage.

In other words, apneas appearing at, say, 13 , might not be because your pressure was at 13 right then. Even if your pressure had had to move up to 13 in response to flow limitations and snoring, the pressure of 13 might still not have been high enough to prevent some of the "REM" or "on your back" apneas.

That's just a guess on my part. I really don't know. But I do know the machines make pressure changes rather slowly and gradually. They don't just yo-yo the pressure up and down suddenly. If the minimum pressure of an autopap, or the minimum EPAP pressure of a BiPAP Auto, is not high enough to keep the throat open, collapses can start hitting before the machine has had time to work its way up to a level that would have prevented the collapse in the first place.

I look only at the other graph you posted -- the first graph that appears on page 4 of an Encore report, titled "Sleep Therapy Daily Details." On that graph, it sure looks to me as if the EPAP pressure needs to be set higher to try to prevent most apneas from the get-go.

That's what I'd try, anyway, for a week or so. Raising the EPAP (and the IPAP.) If that didn't result in improvement in the AHI, I'd figure I was on the wrong track and would look for more ways to work on it.

They moved it from EPAP=5 to EPAP=8 when I told them it was hard to breathe.... then I moved it to 9. I don't know how they came up with the numbers.. maybe they thought the BiPAP Auto would do all the work.

Bernard

Yup. Sounds like what they thought.

[BML]

Why do my OA's increase in number with my increases in pressure?

Bernard, I don't know. I never bother to even glance at the "Summary of Daily Events Per Hour" charts from the Encore report. ozij or someone else more "math" inclined than I am can probably understand the "why" of it, but I don't even try to make sense of that particular chart on my reports.

The thought that occurs to me is...It may not be that the increases in pressure are actually causing an increase in Obstructive Apneas.

The apneas you see listed at certain pressures might be ones that sneaked through during a time when you were on your back and/or were in REM -- two scenarios when apneas are most apt to hit and when more pressure is usually required.

(...)

In other words, apneas appearing at, say, 13 , might not be because your pressure was at 13 right then. Even if your pressure had had to move up to 13 in response to flow limitations and snoring, the pressure of 13 might still not have been high enough to prevent some of the "REM" or "on your back" apneas.

That's just a guess on my part. I really don't know. But I do know the machines make pressure changes rather slowly and gradually. They don't just yo-yo the pressure up and down suddenly. If the minimum pressure of an autopap, or the minimum EPAP pressure of a BiPAP Auto, is not high enough to keep the throat open, collapses can start hitting before the machine has had time to work its way up to a level that would have prevented the collapse in the first place.

(...)

That's what I'd try, anyway, for a week or so. Raising the EPAP (and the IPAP.) If that didn't result in improvement in the AHI, I'd figure I was on the wrong track and would look for more ways to work on it.

Rested gal,

I see your point. I will try higher EPAP and IPAP. I'm a bit nervous about increasing my IPAP but if I understand the 'Auto' part of my therapy, it won't go to IPAP=20 unless there is good reason to... especially if I increased the Max pressure support.

Thanks to all for your input!
Bernard