Auto BiPAP - PR System One vs. S8 / S9 VPAP?

Good Morning!

I have not posted in a while as I have not had much to say. Since December I have been on a PR System One Auto BiPAP. My AHI is still in the 12 - 14 range. My 90% average pressure is usually in the 9 IPAP and 5 EPAP range.

I was wondering if I should try a different model of bi level machine? Do you think perhaps a Resmed S8 or S9 Auto VPAP might improve my AHI? I have 0 leak rate. I've read that the Resmed machines have a different method of determining what pressures to use in auto, maybe it would work better for me?

Thanks for any ideas.

how are you getting your numbers? Is it just off the LCD or are you getting it from some form of software on your computer?

If you're getting it from software... then can you post a report or two? If you're getting it from the LCD... you do realize that it's a rolling average, don't you?

Wondering what your leak rate is from the software... whether you have large leaks... how much of your AHI are centrals, etc...

Mask2sleep,

cflame1 raises an important question: How are you getting your numbers? The on-screen data on the System One is very, very limited. The AHI is only 7 and 30 day rolling averages and is not broken down at all by event type. The breakdown of events may be very relevant in getting at the bottom of why your therapy is not yet up to snuff in the sense reducing that AHI to below 5. And that in turn may be the key to figuring out how to make therapy make you feel better. Because on a very old thread you wrote:

I have been on xPAP since August, so about 4 and a-half months now. During titration they discovered that normal CPAP gave me centrals, so I am on BiPAP.

Now, if most of your remaining events are being flagged as CAs, then it may mean that you and your doc really need to think about whether you need a BiPAP/VPAP S/T machine running in T mode or with a T-mode back up rate. Or whether you actually need an ASV machine. Why? Well, you were getting centrals during your titration study at pressures that were sufficient to prevent the OA's from happening, and if the BiPAP is still inducing CAs in great numbers, then you've most likely got Complex Sleep Apnea, which is a whole lot tougher to treat than plain old OSA.

But if most of your remaining events are being flagged as OAs or Hypopneas, then it may simply be a case of bumping up the EPAP (for OAs) or IPAP (for Hs) and seeing if your overall AHI improves and you start to feel better.

And the only way to tell what kind of events are causing the elevated AHI is to look at the data in some software. So---if you don't have Encore Viewer, I urge you to look at SleepyHead. Yes, it's still Alpha-ware and there are bugs (that are being worked on continuously by the very dedicated and hardworking jedimark). But SleepyHead will let you see all that extra data that the PR System One actually records but does not show on the LCD. An YOU need to see that data for yourself. And on a regular basis. That's the only way you will know whether you need to bring up the issue of CompSA with your doc. Because you've written (in another old thread):

My doctor said something that bugged me yesterday which makes me worry about his plans (if any) on what to do in a month a half if things haven’t changed: “Sometimes you have to compromise on the benefits and get the best you can since the higher pressure didn’t work for you.”

So it doesn't seem likely that your doc is interested enough in looking at the breakdown of events and sorting out whether you really have CompSA and need a machine designed to treat it. Hence, you'll need to be your own advocate and point out what kind of events your machine is recording and push the doc into considering a switch to a more sophisticated machine if your remaining events contain really large numbers of CAs.

And by the way, the System One's on-screen "Percent time spent in Large Leak" data are virtually meaningless: Not only is 1% of seven nights of data a very long time, but also PR doesn't seem to define or describe what constitutes a Large Leak anywhere. All I know is that I've used my System One BiPAP Auto for 8 months now. And I've registered one minute of time in Large Leak in all that time. Looking at my leak lines, I know that I don't have any serious leak problems, but I do have nights with leaks: Sometimes I've adjusted the headgear extra, extra loose due to a migraine; sometimes there's been a bit of an issue with 15--20 minutes of mouth breathing due to allergies; most of the time it seems to indicate my pillows are aging and need to be replaced. My point is this: I know by looking at the leak data in Encore Viewer and in SleepyHead that I do get a leak that's a potential comfort issue once or twice a week. I know by looking at the leak data in Encore and SleepyHead that I get a leak that would be pushing the Red Line in ResScan a couple of times a month. And none of that shows up in the "Percent time spent in Large Leak."

Mask2sleep wrote: I was wondering if I should try a different model of bi level machine? Do you think perhaps a Resmed S8 or S9 Auto VPAP might improve my AHI? I have 0 leak rate. I've read that the Resmed machines have a different method of determining what pressures to use in auto, maybe it would work better for me?

As I said before, given your history of CAs on your titration study, you really need to know whether your AHI is so high because of a large number of CAs. If that's the case, switching to a different bi-level probably won't do much good. If you are still having lots of CAs, then you probably have CompSA and you probably need a bi-level S/T or an ASV machine in that case.

But, if your current AHI figures are high because of Hypopneas or OAs, then yes, a switch to a Resmed S9 Auto VPAP might help. I'd not recommend going with the S8 VPAP because it's an older model and has a proprietary data card. And it's near impossible to find the proprietary card reader to look at your own data. The S9 VPAP uses a standard SD card.

My understanding of the differences between the two Auto algorithms is this:

Both the Resmed S9 VPAP Auto and the PR S1 BiPAP Auto have algorithms that automatically adjust the IPAP and EPAP pressures in response to the various events detected by the machine. But the two companies have taken quite different approaches in their algorithms. Informally this difference can be described as follows:

• The Resmed S9 VPAP adjusts BOTH the EPAP and IPAP by the same amount in response to OAs, hypopneas, snoring, and flow limitations. Like the S9 AutoSet, the VPAP tends to respond quickly to clusters of events and then slowly reduces both pressures back down at the same rate until more events occur.
• The PR S1 BiPAP Auto adjusts EPAP and IPAP independently of each other: EPAP is increased in response to OAs and snoring, and IPAP Is increased in response to hypopneas, flow limitations, and RERAs. In addition to these things, the PR S1 also uses the same "hunt and peck" algorithm that the PR S1 Auto uses to test whether the shape of the wave flow data improves with a slight increase in pressure. The hunt and peck algorithm is only applied to the IPAP pressure for increasing pressure. After events that trigger an increase in IPAP or EPAP are resolved, the S1 does a reverse hunt and peck to find out how far it can lower the pressure: As long as the flow wave remains stable, the PR keeps lowering the appropriate pressure, but if the flow wave becomes more ragged, the S1 will raise that pressure back up to the last level where the flow wave was stable

To make the some of the differences between the two machines' auto algorithms clearer, we need to introduce a setting that only Auto Bi-level PAP machines have---the PS (pressure support setting). Loosely PS is the difference between IPAP and EPAP and the value of the PS setting affects the way the EPAP and IPAP pressures are adjusted. The way PS is implemented on the S1 and the VPAP is quite different however:

• On the S1 BiPAP Auto, the PS setting is the maximum allowable value for IPAP - EPAP. And the minimum value the S1 will allow for IPAP - EPAP is 2. The upshot of this is that whenever 2 < IPAP - EPAP < PS, the IPAP and the EPAP are allowed to vary independently of each other. But when IPAP - EPAP = 2 or IPAP - EPAP = PS, there are some constraints on how the pressures are increased or decreased.
  • When IPAP - EPAP = PS:
    • if the IPAP needs to be increased, then both IPAP and EPAP will increase at the same rate
    • if the EPAP needs to be decreased, then both IPAP and EPAP will decrease at the same rate
  • When IPAP - EPAP = 2:
    • if the IPAP needs to be decreased, then both IPAP and EPAP will decrease at the same rate
    • if the EPAP needs to be increased, then both IPAP and EPAP will increase at the same rate.
  • And at the start of the night, EPAP = min EPAP and IPAP =min EPAP + 2.
• On the VPAP, the PS setting is the fixed value for IPAP - EPAP. Hence IPAP and EPAP are always increased together on the VPAP. (And that's why the ResScan reports for VPAP mahcines can show the pressure info with only one curve.) At the start of the night EPAP = min EPAP and IPAP = min EPAP + PS.

Of course the big questions are: Which system is more effective? and Which system is more comfortable? As a mere patient, I haven't the foggiest if one of these systems is inherently better at treating apnea. And obviously both machines have been run through the full range of efficacy testing required by the government. But it's easy to believe that some folks might respond better to one of the two algorithms than the other. And you're not responding well to the System One's algorthm (in the sense of your AHI), so maybe a trial on the VPAP might be worth doing---provided that your problem is NOT CompSA.

I am always amazed by the breadth of knowledge the folks on this forum know. Thank you.

I had a copy of encore but it simply would never running on m computer for some reason. I bought a card reader that I never got to work either. So this data is just from the LCD. I am reluctant to try a ASV study as it may be a waste of time. I can't take pressures above 13 or so. I can't sleep at all and the air that builds up is too painful. Given that, a ASV would be of limited use. If I can get a card reader to work I will try sleepyhead for more data.