Vauto and flow limitations = higher AHI?

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Jlfinkels
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Vauto and flow limitations = higher AHI?

Post by Jlfinkels » Tue Jan 25, 2022 7:57 am

Now that I’ve been using the Vauto for a month I have a question I need help from those more knowledgeable.

When I was using the ResMed Airsense 10 Autoset (first 10 months of therapy) I typically used a pressure of 11-20 with an EPR of 3 resulting in a typical AHI of 0.5. Setting up the ResMed AirCurve 10 Vauto with a min EPAP of 8 and max IPAP of 20 with PS 3 (which I thought was roughly the same settings) my AHI is between 1-2 averaging 1.5. I’ve tried setting the Vauto PS to 4 and that causes a spike in CA, so I’ve settled on a PS of 3 for now. Qualitatively my sleep is similar but I do notice more wake-ups with the Vauto that I think may be related to the increase in events.

What I noticed is that the Vauto does a great job with flow limitations (95% FL usually 0.0), so much so that the median pressure is 10 and 95%/99.5% pressure rarely goes above 12. With the Autoset (95% FL 0.14) the median pressure was around 12 and 95%/99% was usually around 15. As a result with the Vauto my events have more H/OA but primarily CA, as compared to the Autoset where they are almost all a few CA.

My question is that in my case as the Vauto is so efficient dealing with FL, do I need to bump up the min EPAP a bit to get into the same sweet spot of 95%/99.5% pressure as the Autoset, given that the FL will not drive up pressure? Alternatively I could try setting PS to < 3 and see if that allows enough FL through to get a higher pressure to deal with the H/OA events and reducing CA. I’m thinking of trying the Vauto min EPAP of 10, max IPAP of 20, PS 2, to get to results closer to the Autoset.

I know Pugsy, Palerider, and others, are well-schooled in Vauto and Autosets, so your suggestions will be much appreciated rather than me taking wild attempts at finding good settings. I have plenty of OSCAR graphs I can post if anyone wants to set them, but I’ve attempted to give a good synopsis of the past 11 months here.
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Pugsy
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Re: Vauto and flow limitations = higher AHI?

Post by Pugsy » Tue Jan 25, 2022 9:11 am

I am confused....you want to reduce the AHI that is primarily made up of CA/centrals with pressure changes????
You know that usually doesn't work out so great unless the pressure is triggering the centrals and if that is the case one wants less pressure not more....if centrals is what we are worried about.

And you report maybe a few more wake ups now also reporting more CAs/Centrals???? than compared to AutoSet results?
Have you done your home work and zoomed in on those centrals to see if they are even real asleep centrals or just arousal related???

How much of an increase in centrals do you get with PS of 4 compared to PS of 3? Just how many centrals are we talking about here?
Giving overall AHI numbers without the event category breakdown is pretty much useless.

Might be nice to also see the actual FL graph when talking about flow limitations and maybe trying to reduce them.

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Jlfinkels
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Re: Vauto and flow limitations = higher AHI?

Post by Jlfinkels » Tue Jan 25, 2022 9:29 am

Apologies for not being more precise. I’m not concerned about the centrals as the increase is seemingly triggered with a PS of 4 vs a PS of 3, so I think I know how to deal with it. What I am trying to figure out is how to deal with the obstructive/hypopneas with pressure as it does not seem to raise the same on the Vauto as with the Autoset. I’ll post some graphs when I get home this afternoon. Thanks!
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Pugsy
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Re: Vauto and flow limitations = higher AHI?

Post by Pugsy » Tue Jan 25, 2022 9:35 am

If you are concerned with OAs/hyponeas....more minimum EPAP is what you need to try.
And make darn sure the OAs/hyponeas are real asleep flagged events as well.
We can have false positive arousal related OAs and hyponeas as well.....it's not limited to just centrals.

Before doing anything....make sure what you are trying to kill is able to be killed with a pressure changed.
We don't fix arousal related false positives with more pressure...instead we try to fix the underlying cause of the poor sleep that is causing the arousal in the first place.

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Jlfinkels
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Re: Vauto and flow limitations = higher AHI?

Post by Jlfinkels » Tue Jan 25, 2022 12:07 pm

For anyone interested two random samples. The first is from the Vauto and the second from the Autoset. Note the significant drop in FL in the first one that keeps the pressure for being raised in response, which in turn allows more events.

Screen Shot 2022-01-25 at 8.33.19 AM.png
Screen Shot 2022-01-25 at 8.32.02 AM.png
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palerider
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Re: Vauto and flow limitations = higher AHI?

Post by palerider » Tue Jan 25, 2022 9:28 pm

Jlfinkels wrote:
Tue Jan 25, 2022 7:57 am
When I was using the ResMed Airsense 10 Autoset (first 10 months of therapy) I typically used a pressure of 11-20 with an EPR of 3 resulting in a typical AHI of 0.5. Setting up the ResMed AirCurve 10 Vauto with a min EPAP of 8 and max IPAP of 20 with PS 3 (which I thought was roughly the same settings
Those would have been similar settings, but those are NOT the settings that were used in the Autoset pic that you posted.
You had min 8, EPR 3 in the pics you posted, which gives you an pressure between breaths (EPAP) of 5, which explains why you had so many more flow limitations.
Jlfinkels wrote:
Tue Jan 25, 2022 7:57 am
What I noticed is that the Vauto does a great job with flow limitations (95% FL usually 0.0),
No, it's the higher EPAP doing that.
Jlfinkels wrote:
Tue Jan 25, 2022 7:57 am
so much so that the median pressure is 10 and 95%/99.5% pressure rarely goes above 12.
I really hate the reliance on those statistical numbers, they don't give the full picture. any more than a photograph tells you all that happened in a marathon.
Jlfinkels wrote:
Tue Jan 25, 2022 7:57 am
With the Autoset (95% FL 0.14) the median pressure was around 12 and 95%/99% was usually around 15. As a result with the Vauto my events have more H/OA but primarily CA, as compared to the Autoset where they are almost all a few CA.
If you want a lower AHI with the autoset, then raise your MinEPAP.
Jlfinkels wrote:
Tue Jan 25, 2022 7:57 am
My question is that in my case as the Vauto is so efficient dealing with FL,
That's not what the issue is, the VAuto doesn't do any better dealing with FL at the same pressure support as the Autoset had than the Autoset does. they're using the same auto algorithm.
Jlfinkels wrote:
Tue Jan 25, 2022 7:57 am
do I need to bump up the min EPAP a bit to get into the same sweet spot of 95%/99.5% pressure as the Autoset,
Forget the 95% pressure, it doesn't *mean* anything, other than "oh, huh, I see what the max pressure got up to". But, yes, you should raise the EPAP, say by one, *and then see what your data looks like*, disregarding the 95% (and median) numbers... Sleep changes every night, trying to hit some pressure statistic isn't going to lead to success.
Jlfinkels wrote:
Tue Jan 25, 2022 7:57 am
given that the FL will not drive up pressure? Alternatively I could try setting PS to < 3 and see if that allows enough FL through
You're not going to increase your sleep effectiveness by causing *MORE* sleep disturbing breathing problems.

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Jlfinkels
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Re: Vauto and flow limitations = higher AHI?

Post by Jlfinkels » Tue Jan 25, 2022 9:53 pm

Thanks for the most helpful explanations. The graphs were just random ones I grabbed, I should have looked more closely at the settings. Mea culpa.

I’ll give raising the min EPAP by 1 a go and watch it for a few days before changing anything. Once things stabilize I’ll report back.

Thanks again!
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