ASV users: the everything ASV thread.

[BrianinTN]

Happy to try to help. This is probably a good time for me to attach my usual caveat though that I'm just another ASV user with no particular medical background, so don't put too much stock into my thoughts!

Your overall PTB numbers don't look too horrible to me. People with severe cases of central apnea often have much worse numbers. It is possible for the ASV to introduce an iatrogenic effect of decreasing your PTB (and therefore your work of breathing) given some settings. Both JIMCHI and I found that was the case if the minimum pressure support was too high. For example, take a look at what a large PS gap did to me on my BiPAP S/T when my EPAP was already fairly high:


Your min PS is certainly higher than some, but just looking at your graphs, I'm not sure that's the problem. That said, it does look like the majority of your big valleys in PTB occur when the ASV is increasing IPAP. Ultimately, experimenting with lowering your min PS may be something to try -- but that should only come after getting your min EPAP "right." Let me articulate one of the reasons why...

A byproduct of lowering the min EPAP is that it will lower the min IPAP as well, even leaving min PS the same. Putting that gibberish into concrete numbers for you, since you currently have min EPAP=7 and min PS=5, that means your min IPAP is 12. However, if you experimentally try min EPAP=6 and don't touch min PS a tall, your min IPAP will be 11.

So if it were me (cue all the caveats about me not being a doctor), if the sleep quality remained poor, that's probably what I would try out next. If that caused new residual obstructive apneas or hypopneas, that would be a signal you are probably headed in the wrong direction.

[ameriken]

So if it were me (cue all the caveats about me not being a doctor), if the sleep quality remained poor, that's probably what I would try out next. If that caused new residual obstructive apneas or hypopneas, that would be a signal you are probably headed in the wrong direction.

Thanks Brian.

I will make the change tomorrow on my epap. I don't see a big problem doing it, my AHI is not bad, and as I said in another post if I call my sleep doc, he's already guaranteed me that he never returns any calls. I'm in the VA so it's not like I can find another sleep doc, plus being the weekend, they're all off anyway.

A slight change like that isn't going to hurt, I'll give it a try and watch the #'s, I'm glad I've got the software now to watch.

Thanks for checking in, I appreciate your help.

[ameriken]

July 8 to 9

Not too bad, AHI of 3 again. And I finally figured out how to get a better quality photo uploaded.

[BrianinTN]

How do you feel today? We're still seeing the same thing I mentioned before (higher IPAP <--> lower PTB), but the thing that's a bit frustrating about our machines is it's really hard to tell whether it's the chicken or the egg.

[ameriken]

I'm ok today, but I didn't lower the EPAP last night, got in late and just went to bed so the setting are the same as before.

However, I did it set it down to 6 for tonite so we'll see what happens and how I feel tomorrow.

[ameriken]

Last nite, after dropping EPAP down to 6. Not sure if it helped, still AHI of 3, all being hypopneas.

[BrianinTN]

Your EPAP line is almost completely flat. The ASV almost never raised your EPAP for very long, and when it did (toward the end of the night), it only did so my the smallest of margins.

As such, your data generally support my theory that (at least according to the ASV's processing of the data) a lower minimum EPAP is appropriate for you. I would personally suggest giving it a few more nights, always recording how you feel after each night (maybe on a 1-10 scale, so you can computer an average "feeling" index across all nights at the given settings), and then take it down to min EPAP=5.

[ameriken]

I do feel somewhat better today and I started a sleep journal as well, it's something I've been wanting to do anyway.

I notice though, the PTB's are still down. I wondered if a higher EPAP may tackle that? Have you tried the opposite...going with a higher EPAP and if yes, what did that do to your results?

[BrianinTN]

My personal experience has been that my PTB has been a little lower with higher pressures, although the difference has been negligible. That being said, I don't generally have much of a problem with PTB, so my own data is not a very good reference. The only time I notice it dropping a lot is when the ASV is increasing IPAP all by itself, so like I mentioned previously, I don't know which is the chicken and which is the egg.

[ameriken]

Last night 07/10-07/11. Hypops down to 2. PTB's higher, which looks pretty good especially the first 2 hours or so.

Brian, I welcome you or any other ASV users to post their results here. I'd really like to find ways we can maximize the effectiveness of these machines so we can maximize our sleep.

I know there's got to be at least a few more users here.

[ameriken]

One other thing I've noticed. I take a 30 to 60 minute nap almost every day and it is during these naps that I sometimes have my highest AHI's. I took a 50 minute nap yesterday afternoon and had an AHI of 11 (all hypops). Then a 2 overnight.

The only thing I can see that is different other than time of day, is when I nap I am on my back, and at night I sleep on my sides.

[BrianinTN]

I take a 30 to 60 minute nap almost every day and it is during these naps that I sometimes have my highest AHI's. I took a 50 minute nap yesterday afternoon and had an AHI of 11 (all hypops). Then a 2 overnight.

The only thing I can see that is different other than time of day, is when I nap I am on my back, and at night I sleep on my sides.

Same here. My AHI routinely is between 11 and 18 when I take afternoon naps, but I have it pretty stable right now below 4 at night. Positional apnea sounds like it could be an explanation for you. That may help explain it a little for me, as might my nighttime prescriptions. Do you take any prescriptions or OTC drugs at night before going to sleep? For me, Remeron (mirtazapine) has been a little AHI miracle and has dropped my average AHI to around 2-3 when combined with Lunesta.

I know there's got to be at least a few more users here.

You're right about that! Part of the problem is that all of us Respironics ASV users I've seen posting (Paper_Nanny, Bons, JIMCHI, Mr. Bill) are confused about various issues too.

Hypops down to 2. PTB's higher, which looks pretty good especially the first 2 hours or so.

So one thing I keep forgetting to mention to you is this: you can "fake" an apnea by simply holding your breath for a little bit. (I think the machine believes it is responding to a central apnea, since you won't have VS or other symptoms of an obstructive event, but someone should double-check me on that.) The ASV will respond by increasing pressure. My quasi-educated guess is that's what your graphs are showing: you have a segment of time of CSA or periodic breathing, and it increases IPAP accordingly. The light blue shaded area that surrounds the maroon bar representing IPAP represents the range of IPAP values the machine is able and willing to try. This exists because it would be disruptive to jack your IPAP all over the place willy-nilly, so based on the data from the preceding few minutes, the ASV decides what range is appropriate and continues to re-calculate it. During periods of time where your breathing is highly stable, you'll notice that light blue shaded area is very small. It's an adaptive process, hence the "A" in "ASV."

My gut still says that you'll have luck with min EPAP=5 before all is said and done. For reference, below is my data from last night. Note the similarity to yours; the one time my PTB plummets, IPAP increases at the same time.


By contrast, check out a night of data from the end of May, when I was experimenting with min EPAP=7 and min PS=3.

[ameriken]

Same here. My AHI routinely is between 11 and 18 when I take afternoon naps, but I have it pretty stable right now below 4 at night. Positional apnea sounds like it could be an explanation for you. That may help explain it a little for me, as might my nighttime prescriptions. Do you take any prescriptions or OTC drugs at night before going to sleep? For me, Remeron (mirtazapine) has been a little AHI miracle and has dropped my average AHI to around 2-3 when combined with Lunesta.

I don't take anything prior to bed, but in the morning I take methadone for back pain and that holds me for the rest of the day. Doc thinks that is triggering some of the low PTB's, PB's, and CA's. Which is another reason why I don't take the methadone at night.

So one thing I keep forgetting to mention to you is this: you can "fake" an apnea by simply holding your breath for a little bit.

Yeah, I've done that one purpose just to get an understanding of how the machine works. When it doesn't sense a normal inspiration, it kicks up the pressure to force a breath.

(I think the machine believes it is responding to a central apnea, since you won't have VS or other symptoms of an obstructive event, but someone should double-check me on that.) The ASV will respond by increasing pressure. My quasi-educated guess is that's what your graphs are showing: you have a segment of time of CSA or periodic breathing, and it increases IPAP accordingly. The light blue shaded area that surrounds the maroon bar representing IPAP represents the range of IPAP values the machine is able and willing to try. This exists because it would be disruptive to jack your IPAP all over the place willy-nilly, so based on the data from the preceding few minutes, the ASV decides what range is appropriate and continues to re-calculate it. During periods of time where your breathing is highly stable, you'll notice that light blue shaded area is very small. It's an adaptive process, hence the "A" in "ASV."

My gut still says that you'll have luck with min EPAP=5 before all is said and done. For reference, below is my data from last night. Note the similarity to yours; the one time my PTB plummets, IPAP increases at the same time.

By contrast, check out a night of data from the end of May, when I was experimenting with min EPAP=7 and min PS=3.

I think in the next couple of nights I'll drop the EPAP to 5.

You posted a report at the top of the page that shows your PTB's were really low and all over the place. The one from last night shows a huge improvement. What do you think has helped it? The lower EPAP? Lower PS? A combination? Has it taken time and gradually gotten better or was it kinda like an overnight improvement?

[BrianinTN]

You posted a report at the top of the page that shows your PTB's were really low and all over the place. The one from last night shows a huge improvement. What do you think has helped it? The lower EPAP? Lower PS? A combination? Has it taken time and gradually gotten better or was it kinda like an overnight improvement?

That early report was on a BiPAP S/T, which is essentially just a machine that supports a single EPAP, single IPAP, and a backup rate (which kicks in if you don't take a breath). Our ASVs, on the other hand, can vary the EPAP and IPAP as needed.

But the main reason why my PTB was horrid on the BiPAP there had to do with the combination of high pressures and too high of a PS. 20/13 (i.e., PS=7) was doing too much of my work of breathing and therefore was suppressing my respiratory drive. 20/16 (i.e., PS=4), on the other hand, was better for PTB, but left my AHI in the 20s to 30s.

Now that I'm on an ASV and am using much lower pressures (min EPAP of 4), I find that my PTB is reasonable and my AHI is OK (average below with "reasonable" min PS values. Anything from min PS=0 to min PS=5 works fine for me. I find min PS=5 most comfortable when using my Swift LT nasal pillow mask and min PS=0 most comfortable when using my Fisher & Paykel 432 full face mask. Both of those configurations yield very similar PTB and AHI numbers.

[BrianinTN]

I keep meaning (and forgetting) to ask you: have you obtained a a copy of your sleep study results from your doctor? If yes, would you mind posting it? If not, I'd suggest asking your doc for it. Seeing the study details can help figure out a whole bunch of stuff.