New machine, new results

[tmoody]

In a different thread, a couple of months ago, I described how I had started getting erratic results with my Philips System 1 ASV. The machine was going on seven years old, and I wondered if it was just failing. I had been trying for well over a year to get a new machine from the DME, since this machine was recalled anyway. Then I went on a three-week holiday in Portugal, and when I got back, called the DME again. To my utter shock, they had an AirCurve 10 and I could pick it up that day!

Without going into too much detail, my AHI with the Philips machine was usually between 2 and 3, with almost all the events showing as hypos. As I say, during the last couple of months of 2022, I started seeing AHIs of 7, 8, 11, and such, still virtually all hypos.

When I started with the AirCurve, on January 16, I was astonished to see my typical AHI drop to close to zero. In fact, it was zero on more than a few nights, and the rest of the time it was typically 0.1 or 0.2. Once it went up to 1.

So, during my telemedecine consult a few days ago, I mentioned that, although I'm very pleased with my results with the AirCurve, I was still curious about my centrals, since my titration study, years ago, didn't show any at any pressure. The PA said she could remotely set the machine to continuous pressure mode and we could experiment. So we did that last night. I've attached the Oscar data. This was my first time looking at Oscar data from the ResMed machine.

I'm struck by a few things. First, there is no separate reading for central/clear airway events. Just a lot of "UA" unidentified ones. Second, unlike the Philips data, there's no measurement of "patient triggered breaths". Does ResMed simply not score these things?

Anyway, the plan is to repeat the experiment tonight, to see what happens. But I take it these "UAs" could be centrals?

[srlevine1]

The first thing that came to mind when looking at your data was the need to cure your large leak (20.93%) issue which can alter reported results during that period of time. I will leave it up to the better-informed forum members with ASV experience to comment further.
You may also want to verify that under File-Preferences - Events Tab you have Clear Airway checked.

Best,
Steve

[tmoody]

Thanks. 

I did the experiment again the next night: CPAP mode, no ASV or auto. This time there was almost no leak time. AHI went down to 14, mixed between hypos and "unidentified" events. 

Tonight, I'll return to prescribed ASV mode.

But I did look in Preference>Events and found that Clear Airway is already checked. But it's not showing up in the report, for some reason. I suspect the machine just isn't flagging them, but I have no idea why not. Seems odd.

And even in ASV mode, it doesn't track patient-triggered breaths, as the Philips did. You'd think that would be important in an ASV system.

[Crimson Nape]

I believe that since the ASV is designed to address CAs, they are not reported on this model. As I remember, they will show up as UAs.

- Red

[Sleeprider]

Red is correct, the Aircurve 10 ASV does not use the forced oscillation technique (FOT) to determine whether apnea is obstructive or central. If you were using an ASV due to complex apnea, I'm not surprised that it resulted in a very high CAI in CPAP mode. I have no idea what any tech was thinking to switch from ASV to CPAP without a doctor's order or knowledge of your sleep beathing disorder.

I'm not clear on why you were confused about the lack of centrals using this machine. We commonly see zero centrals with the ASV as it is specifically designed to eliminate them. Most of the time when we see clusters of UA like yours, we assume they are obstructive because in ASV mode centrals simply cannot occur.