AHI vs Pressure Sweetspot

[Catnapper]

Hi everyone,

My new auto bipap is so very nice. I have used it for a month now and would like to post the chart from Encore Pro Analyzer that shows AHI vs Pressure.





Is this what is called a sweet spot? at 8.9?

I have never been sure about the discussions of this topic.

Thanks for any clarification.

Catnapper - Joanie

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CPAPopedia Keywords Contained In This Post (Click For Definition): bipap, Encore Pro, AHI, auto

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CPAPopedia Keywords Contained In This Post (Click For Definition): bipap, Encore Pro, AHI, auto

[DreamStalker]

Actually your "sweet pot" is closer to 9 cm although to be more precise it is between 8.8 cm and 9.0 cm.

As for how you set a bipap for that sweet spot ... I'll let a bipap expert tell you that ... I'm an apap kind'a guy.

[SelfSeeker]

Hi Joanie,

I guess your best pressure would be 9. Or the pressure you get the least amount of apneas.

I am surprised that it went high on 10.

Unless you left a wide window open for a while the chart may not be as accurate. If you were tweaking different pressures during the month the, I am not sure how it would effect the graph.

It is intresting how the curve dips just before 9, there are no points there because the machine does not go there.

* Anyone remember the French Curves and drawing graphs. LOL *

How do you feel with your Bipap?

[Ergin]

For me sweetspots obtained from AHI vs P plot are nonsense.
Your AHI seems low at 9cm, but are you sure that's during REM stage?
These machines, unfortunately, do not tell anything about the events at
REM nor arousals.
To have a better understanding we have to know your titrated pressure.
If that's 9cm as well, you might have to lower your upperbound.

[Snoredog]

you always want it on the down stroke so I'd say 8.8cm is your number.

What is your IPAP set for? what does FL's look like?

and can you make that graph BIGGER?

[jskinner]

I have used it for a month now and would like to post the chart from Encore Pro Analyzer that shows AHI vs Pressure.

Joanie,

Looks like you might be using an older version of EPA? Newer versions have separate AHI vrs IPAP and EPAP

[DreamStalker]

For me sweetspots obtained from AHI vs P plot are nonsense.
Your AHI seems low at 9cm, but are you sure that's during REM stage?
These machines, unfortunately, do not tell anything about the events at
REM nor arousals.
To have a better understanding we have to know your titrated pressure.
If that's 9cm as well, you might have to lower your upperbound.

That's too bad your machine doesn't give you a sweetspot that makes any sense. I have the Remstar Auto "tank" model and I was able to find my sweetspot ... it is a bit higher than my titrated pressure. I also have an S8 Vantage and found my sweetspot with it (pretty close to the tank) ... also a little higher than my titrated pressure. Maybe there is something wrong with your machine ... or your mask ... or you have inconsistent mouth leaks ... or something else.

You are right about PAP machines not being able to provide much info on REM stage ... EEG is best for that kind of data -- you know, all those wires and stuff connected to your head that make you look like some kind of remote controlled droid robot.

Also, true that the titration pressure provides a good starting point ... that is if you had a competent titration to begin with. I wuz pretty lucky with mine ... not too far off.

Best of luck!

[Goofproof]

For me sweetspots obtained from AHI vs P plot are nonsense.
Your AHI seems low at 9cm, but are you sure that's during REM stage?
These machines, unfortunately, do not tell anything about the events at
REM nor arousals.
To have a better understanding we have to know your titrated pressure.
If that's 9cm as well, you might have to lower your upperbound.

I'd have to go along with your thinking somewhat, first, the "Sweet Spot", can't be based on one nights data. I consider the "Sweet Spot", to be the pressure where you have the lowest AHI overnight, over a period of days.

This is found by slowly increasing the pressure by .5 CM, over a period of days, as long as the AHI goes down and you sleep well, keep going up by .5 CM, until AHI starts to rise. When testing no other changes can be made, and if your health changes (cold or whatever) you can't do the test at that time. You need to keep the data valid. Your "Sweet Spot", is the point before your pressure goes up. Jim

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CPAPopedia Keywords Contained In This Post (Click For Definition): AHI

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CPAPopedia Keywords Contained In This Post (Click For Definition): AHI

[Catnapper]

I am sorry the graph is so big. I tried to fix it, but couldn't.

My leak rate is very close to what the mask at its pressure should have. I have very few apneas with the therapy, and my AHI averages 1.0 or less. Last night it was 0.1. My leak was 25.4 in a straight line except for a flutter not long before I woke up. I had one night where I had 3 apneas. That was probably what made the graph go up at 10.

My sleep study titration was 13, but in the 8 months I have been tracking my results with the software (first with an M series auto, now the M auto bipap), I have seldom reached 13. My 90% pressure has been as high as 12 a few nights but is usually 10.

Currently my bipap is set with EPAP at 6 and IPAP at 13. It has been that way except for the first few days.

I hope that answered the questions. Thanks for the advice. I have version 0.8.7 of Encore Pro Analyzer.

Joanie

[jskinner]

I am sorry the graph is so big. I tried to fix it, but couldn't.

To make smaller charts, resize your window to the size of chart that you want before saving the it to a file.

I have version 0.8.7 of Encore Pro Analyzer.

Current version is 0.8.9

[SelfSeeker]

So how far behind the times am I with the 0.8.3 version.

Do the different versions depend on the type of machine someone has. I have the M auto.

Where can I find a newer version?

Current version is 0.8.9

[jskinner]

So how far behind the times am I with the 0.8.3 version.

6 releases

Do the different versions depend on the type of machine someone has.

Nope, same version for all machines.

[StillAnotherGuest]

Is this what is called a sweet spot? at 8.9?

For me sweetspots obtained from AHI vs P plot are nonsense...
These machines, unfortunately, do not tell anything about the events at REM...

Nor can they say anything about body position either. For many, if not most people, pressure requirements vary based on sleep stage, position and perhaps underlying disease state (central-oriented disease tends to require less, or in some cases, no support at all in REM. Course, if you have central-oriented disease, you shouldn't be on auto-anything anyway).

For those reasons, I would generally discourage the use of the term "sweet spot" because it implies that that is the "ideal pressure" for all those conditions, and in some instances, it might be too much, and in others, not enough. And if that surge at 10 cmH2O occurred because of REM, or supine REM, then that 8.9 cmH2O "happy place" doesn't address your most significant problem area.

Currently my bipap is set with EPAP at 6 and IPAP at 13.

Looks like you might be using an older version of EPA? Newer versions have separate AHI vrs IPAP and EPAP

Right, so we really don't know what that single pressure value means, anyway.

My sleep study titration was 13, but in the 8 months I have been tracking my results with the software (first with an M series auto, now the M auto bipap), I have seldom reached 13. My 90% pressure has been as high as 12 a few nights but is usually 10.

And this really suggests that 8.8 cmH2O does not include what may be your most significant issue. If you need 13 cmH2O to address REM events, or supine REM events, then that mountain that the AHI passes through at 10 cmH2O could represent the attack on that situation. Further, it is not clear to me what that "AHI" represents, unless the events are all hypopneas, and the HI is simply buried under the AHI.

I am sorry the graph is so big. I tried to fix it, but couldn't.

If you're still having trouble reducing the image size (down to less than about 750 pixel wide) before you upload it, you can use this link instead:


SAG

[Catnapper]

Thanks SAG

I think I understand better now maybe. If it matters, I didn't have Centrals in my study and no NRs since. I seldom have apneas, almost all hypopneas.

So, this is my new understanding. I would need EPAP of at least 8 or 9 to catch the apneas, and IPAP of 13 or higher to catch the hypopneas or apnea events related to REM or sleeping position. Is that correct?

(I almost never sleep on my back, but I suppose it is possible that I don't know about it - I was asleep!)

I will look through the daily charts I have printed to see at what pressure the apneas occurred to see if that looks right.

I will forget the sweet spot concept entirely since it doesn't appear to be useful for me.

Thanks to all who replied. Every bit of information helps in the process of learning to deal with OSA and the CPAP theraoy.

[DreamStalker]

Is this what is called a sweet spot? at 8.9?

For me sweetspots obtained from AHI vs P plot are nonsense...
These machines, unfortunately, do not tell anything about the events at REM...

Nor can they say anything about body position either. For many, if not most people, pressure requirements vary based on sleep stage, position and perhaps underlying disease state (central-oriented disease tends to require less, or in some cases, no support at all in REM. Course, if you have central-oriented disease, you shouldn't be on auto-anything anyway).

For those reasons, I would generally discourage the use of the term "sweet spot" because it implies that that is the "ideal pressure" for all those conditions, and in some instances, it might be too much, and in others, not enough. And if that surge at 10 cmH2O occurred because of REM, or supine REM, then that 8.9 cmH2O "happy place" doesn't address your most significant problem area.

OK ... but if not "sweet spot", "ideal pressure", or "happy place" ... what term should be used?