Dreamstation False Snoring Detection Problem

[ericmvan]

I'm wondering if anyone else has had this problem, and also posting as a help to anyone who might have it in the future. It's very strange.

I have central apnea that is extremely sensitive to body position, plus a bit of snoring. While on my side and on the machine, I can put up AHI's of <1.0. On my back with the machine, the numbers get very rough, and the waveform looks like bad modern art. On my side without the machine is much less restorative (as I've confirmed during this problem), and on my back without it ... who knows how bad that is? (Bad enough to get me diagnosed.)

(In the course of this, I rediscovered the facts about VS (Vibratory Snore) and VS2 data that were reported earlier. VS events in Sleepyhead are actual events, and are regarded as severe enough that the machine will up your pressure. VS2 events are apparently milder, since they don't trigger a response and are more common. Their total number is counted and reported in 2 minute intervals on the nose (which Sleepyhead mistakenly calls an "event"), and one last time when you turn off the machine.)

To get a baseline, I looked at the last 25 hours or so of normal operation. I averaged 0.25 VS per hour, and 5.1 VS2. Numbers are higher if I can't stay off my back, of course.

One night In December, 84 minutes into a session, my machine suddenly started reporting insane levels of snoring. VS index went up to 33 per hour the rest of that night, and has averaged 49 since the problem became seemingly permanent. That's up 200-fold! VS2 is averaging 275 per hour (up a mere 55-fold).

Sleep waveform almost never shows indications of snoring. With just a couple of exceptions, it shows I'm on my side, and I don't snore on my side.

What I noticed at my end was my mask moving uncomfortably on my face. For instance, the moment I stopped inhaling, it would push hard against it, then move gradually away while I exhaled. Since my pressure generally ranges nicely between 10 and 12 (non-vented mask), I didn't even think of looking at that graph. It turns out that every VS ups the pressure, so I've been sitting at my max of 14 almost the whole time with this problem. And when I'm actually breathing normally, that appears to be bad; the nights that I've tried to bully my way through what seemed to be a mask problem seemed to be no more restorative than no-mask nights.

After three days of struggling with this, I slept without the mask for more than a week. When I tried it again, the problem was gone! Three days later it returned, again in the middle of a session, and the same thing happened the next day ... then a day that was bad from the outset, a day where it was bad intermittently, and since then, nothing but bad. This really seems as if some sort of component failed gradually; there are 36 hours where it worked about half the time, then death.

Furthermore, the VS events are at remarkably regular intervals. For instance, 1:02, 1:03, 1:08, 1:07, 1:07, 1:08, 1:07, 1:08, 1:07, 1:08, 1:05 … Since they’re always marked at or near (ascending) the top of the wave form, much of the variation seems to be waiting for the exact right moment. It’s as if the output of the algorithm that calculates a VS has a false component that builds steadily over time at a fixed rate but gets reset when a VS is reported; the VS report gets triggered when the threshold nears and the real component happens. As VS2 reports are much more variable (from 3 to 20+ in a two-minute window,) they seem to include a permanent false component, i.e., a fixed aberrant hypersensitivity.

I'll be telling all of this to my medical supplier (who are generally excellent), and sending them a copy of my SD card, and hopefully they'll replace the machine under warranty. But it's taken two months of troubleshooting to get to this point; if I'd known then what I've learned since, that could and should have been a week or two.

[ChicagoGranny]

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[JDS74]

My DreamStation ASV reported excessive levels of VS values also.
I sent it off to ACBio for inspection and/or repair. They are waiting parts.
I switched to my backup machine - PR System One 960 and it's VS report hovers around 0.1 with the value frequently being 0.0.

So, yours may be an equipment error/failure of some sort.

[ericmvan]

That's good to hear. My letter and SD card are going off to my supplier tomorrow, and I'll add a note that the problem has been encountered by others.

[JDS74]

ACBio replaced the main board and the problem went away.
In hindsight, I noticed that the Auto On function wasn't working properly - took 6 or 7 breaths tp get the machine to turn on.
Now with the new main board, it turns on in 1 or 2 breaths. Obviously some sensor hard wired on the main board was in partial failure mode.