[Equipment] S9 Autoset - AHI recording correctly?

[Dial999]

[attachment=196]Hi guys,
Firstly, thanks for all the help received already, just by reading the forum.

Using Resmed to look at the graphs, I notice that the blue line for AHI seemed to only record for a short time. Other nights have been the same, the blue line just runs for a few hours, unlike all the other graphs which cover the whole time. The only events listed are within the blue line period, nothing when it is not there. Is the machine faulty?
It is a hire machine, and I've already wasted time with the wrong sized mask, then the heated hose error. Am buying a machine soon.

[Dawei]

Welcome to the board. I'm sure others who have a higher level of expertise will respond, but as you suggested, I think that machine is faulty, since the trace for AHI should be present for the entire sleep period whether it's a flat line at 0 AHI or going up and down during the night. The fact that the pattern of short AHI recording happens again and again would seem to eliminate a one-time glitch.

[Dial999]

Thanks for that reply.
Looking back over the results from the old machine, and results using a new machine I've just purchased, I notice that the AHI line only starts when the first event happens.

I assumed that was because it can't show events if it is not registering them, but now I think the AHI line is just a calculation which only starts calculating after the first event happens.
This does not explain why, in the image I attached, it stopped calculating. Anyone throw any light on this?

[Sleepster]

I'm not familiar with Rescan as I have a PRS1 machine and use SleepyHead. But ... it looks to me like it's a graph of the AHI per hour. As such, when you go a full hour with no events, the AHI per hour drops to zero for that hour. If I'm correct then your graph is correct.

You could try looking at your data in SleepyHead. It also plots a graph of the AHI per hour.

[zonk]

Ditto what Sleepster said. the AHI count is incremented at the occurrence of every event and reset every hour.

[archangle]

The data is there, it's just that it's zero much of the time.

Almost everywhere else but SleepyHead, AHI is only calculated as a daily number, not a per-hour number like SleepyHead does, so beware about comparing that AHI graph number with numbers from elsewhere.