New to ASV, new to SleepyHead

[tmoody]

As suggested, I haven't been looking at my data each day, but I have been keeping a sleep log, which has been uneventful for the most part. But for the past day or two I'd noticed a little scratchy throat, and last night before turning the lights out I sneezed a few times. I noticed my right nostril felt a little congested as I put the nasal pillows on, so I felt the air moving more forcefully through my left nostril. As I was lying there falling asleep, my mouth dropped open a couple of times. I thought to myself, "This probably isn't going to be one of my best nights."

So this morning, I yielded to the temptation to check the AHI and, to my surprise, it was 1.8. Since my average for April has been 3.6, this is one of my better numbers. Not only that, it was all hypos: zero OAs, zero CAs, and even zero periodic breathing. Even my Timed Breaths number was one of the lowest I've seen, at 166, indicating that the machine didn't have to work that hard to keep my breath on schedule last night.

In short, it WAS one of my better nights, despite my cold symptoms. You just never know.

[tmoody]

I'm returning to this thread, because my question is taking the "EPAPmin" thread off-topic.

I'm curious as to why my ASV seldom pushes my EPAP much above 10, even though EPAPmax is set to 23. I still get 20-40 hypos per night, on average, so you'd think it would go higher.

On the other hand, during about four months of APAP, my maximum EPAP pressure averaged around 17, with an 8-20 pressure range, and I still had about twice as many hypos, plus a fair number of OAs and centrals. So obviously there's more to it.

[robysue]

Quotes are from the post on the other thread. The data posted on the other thread looks like this:

I do wonder why my maximum IPAP in a given night seldom goes much higher than about 12, even though the EPAPmax value is 23.

I am not an ASV expert by any means. But it looks like there is some kind of algorithm programed into the machine that dynamically determines a reasonable "local max IPAP" value that is based on both the current EPAP value and parameters that are determined by the shape of the inhalations in the flow rate graph. It looks as though the machine wants to use as little extra IPAP pressure as needed when it starts triggering inhalations. If a little extra IPAP doesn't work to stabilize the breathing OR if the breathing gets ragged in some specific way, it looks like the "max IPAP" algorithm kicks in and increases the local max IPAP so that the machine can add more extra IPAP when it needs to trigger inhalations. Clearly, the local max IPAP only reaches the max IPAP setting when the machine is finding the need to trigger lots and lots of inhalations---i.e. the machine's noninvasive ventilator properties are being used at their max capability to trigger the inhalations.

Last night's maximum [EPAP] was 9.5, but I still had 26 hypos during the night. From my reading on this forum and in the manual (I still don't pretend to have a clear understanding), the whole point of having a variable EPAP with a fairly high maximum is to have enough "ceiling" to increase EPAP pressure to get rid of OAs and HAs.

You are using a PR System One ASV. I am not sure if the "Auto EPAP" algorithm used by your machine is similar to the "Auto BiPAP" algorithm used by the simpler PR System One BiPAP Auto machine. But it looks like it might be.

In the PR Auto BiPAP's "Auto" algorithm, EPAP is increased for clusters of OAs, clusters of OAs mixed with Hs, and snoring. Clusters of Hs result in an increased IPAP, not an increased EPAP.

In your data, there's a distinct cluster of just Hs right before 1:30. It's clear that the EPAP did not increase in response to those Hs. It's less clear, but it appears that the actual IPAP was increased during the cluster and then was lowered after the cluster of Hs appears to clear up. It would be useful to zoom in on the time frame of 1:15 to 1:45 to see exactly what is happening to the IPAP during and right after that cluster of Hs.

I'm not complaining. 26 HAs is still about half of what I was getting on APAP. I'm just curious about why the ASV doesn't bump EPAP pressure a bit higher on those HAs. I guess this question is a bit OT for this thread.

It looks like the PR ASV "auto EPAP" algorithm is similar to the PR BiPAP Auto's "auto" algorithm. See my comments above.

[richb]

Last night, I set PSmin to 1, leaving EPAPmin at 8, so IPAPmin was 9. My AHI crept up yet again, to 5.04, reported as 5.1 on the machine. There was just one CA. Periodic breathing 1%. No OAs. So once again, the AHI was almost entirely hypos.

I think it's going to take a more pressure support to help you through the hypos, I run 5 myself. I'm NOT recommending you just set yours to 5, simply because that's what I'm comfortable with.

but, I do believe that more PS would reduce your hypopneas. that's the recipe that i've always heard. epap for obstructive apneas, pressure support for hypopneas after that.

I think palerider's suggestion is important to consider. As I recall your sleep study showed Central Apnea and periodic breathing (Hypopneas) as your primary problem. I think I also recall that you had a few Obstructive events. Your initial settings EPAP PS and max IPAP should be shuch as to do no additional harm. Keep in mind that traditional CPAP therapy makes Central Apnea worse. Your machine will do this rest with its algorithms. That said your IPAP max needs to be high enough to ventilate you when you forget to breathe and your EPAP min needs to be high enough to keep your airway open during exhalation to prevent the occasional Obstructive event. Based on the SH data you posted your machine is working well enough to keep your AHI below 5. My thinking is that your machine is just adequate. There are newer machines both from PR and ResMed that might work even better because of updated algorithms. I'm not sure if you could convince your Dr. or DME to let you try a newer machine but it might be worth a try. I would probably want to try a machine from ResMed (Aircurve 10 ASV) to see if the algorithms from ResMed work better for you.

Rich

[tmoody]

As far as I can tell, I never max out the IPAP seeing in the course of a night, so that's okay. The highest PSmin setting available in the menu is 2, which is where I've had it for the last week or so. I suppose I can make the case for a better machine at my coming consult, but since turning off flex and going to rise time=1, my AHI has been dropping anyway. It was 1 last night. If that continues, I have no reason to rock the boat.

[tmoody]

Note: Even though PSmin=2 and I can't set it higher, looking at the display on the PRS1 I notice it gives my average PS for the past week and month, both of which are 3.8. So, if I'm understanding this correctly, the gap between PSmin and the average isn't so great that it should cause a problem.

[Sleeprider]

Note: Even though PSmin=2 and I can't set it higher, looking at the display on the PRS1 I notice it gives my average PS for the past week and month, both of which are 3.8. So, if I'm understanding this correctly, the gap between PSmin and the average isn't so great that it should cause a problem.

I think PSmin can be set to a higher value on that machine, at least I could with the auto BiPAP. I thought you started with a higher PSmin originally?

[tmoody]

Note: Even though PSmin=2 and I can't set it higher, looking at the display on the PRS1 I notice it gives my average PS for the past week and month, both of which are 3.8. So, if I'm understanding this correctly, the gap between PSmin and the average isn't so great that it should cause a problem.

I think PSmin can be set to a higher value on that machine, at least I could with the auto BiPAP. I thought you started with a higher PSmin originally?

Originally, as of the titration study, PSmin was set to 0. I've gone into the clinician's settings and raised it, first to 1, then to 2. And that's all there is in that setting.

[richb]

As far as I can tell, I never max out the IPAP seeing in the course of a night, so that's okay. The highest PSmin setting available in the menu is 2, which is where I've had it for the last week or so. I suppose I can make the case for a better machine at my coming consult, but since turning off flex and going to rise time=1, my AHI has been dropping anyway. It was 1 last night. If that continues, I have no reason to rock the boat.

No sense fixing something that is not broken.

Rich

[tmoody]

No sense fixing something that is not broken.

Rich

Exactly. It's one month today since I switched to ASV. My chitchat settings may not be perfect, but they're not bad. Not only that, nasal pillows are still new to me, and I'm still selling in with them. I'm not going to tweak anything for a while and see if I settle I even more. I think I was expecting instantaneous AHI=0. I'm satisfied with the way things are trending now.