SD card vs machine report AHI

[Labromaniac]

Stupidly last night I forgot to reinsert my SD card, so this morning I inserted the card then removed it again to see if the machine would remember any data from the night and write it to the card. As analyzed in OSCAR, The machine did write the start and stop times as well as an AHI score but no wave forms. What was curious is that the OSCAR AHI was 0.2 and the machine score was 0.7.

So,  why the difference? Is a machine generated report (on its little readout screen) differ from what OSCAR figures?

ResMed aircurve 10 ASV

Thanks for your comments!

[Crimson Nape]

What do you have your reporting period set to on your ASV? It will always reset back to the default of 1-month if you lose power.
- Red

[Labromaniac]

Sorry, not sure what that means. I did not lose power, just forgot to have my SD card inserted last night and for that night only.

[Gideon]

Assuming the CPAP and OSCAR are reporting the same period the difference is typically traced to how each rounds the data.

IMHO OSCAR is the more accurate unless you are presenting something we haven't yet seen.

Thus the above questions.

[Crimson Nape]

First, a Resmed's day is from noon to noon.  If you happen to sleep past the machine clock's noon hour, part of your data will be on one day , and the remainder will appear on the following day.  Secondly, all Resmed devices have the option to set the machine's reporting period that appears on the display, 1-Day, 1-Week, 1-Month, 3-Months, 6-Months, and 1-Year.  The default for this parameter is 1-Month.  OSCAR's reporting on the Daily screen will be 1-Day.  So my question is, what is the reporting period set to on your Resmed ASV?

[Labromaniac]

Ahhh all this is very interesting. I checked on my machine in the clinical setup area and it is set to the default of 1 month, BUT I notice that switching to one day does not change the AHI figure either way which appears to be only for the one recent night, BUT the rest of the figures do give averages or figures for the time period selected.

So it appears that the machine screen readout has BOTH a daily figure and then the data for the time period selected. A hybrid of daily and "time period" set.

My data did fall into the noon to noon time frame. Learning tons here!

So perhaps OSCAR was able to interpret some information its own way vs the ResMed machine even though the tracings were not available due to my card not being in the machine this last night.

[Crimson Nape]

If you regularly sleep through your noon hour, the trick is to set your ASV's clock back, so it thinks that it is still on the same day. The object of the game is to look at total hours slept, and not specifically when you did it.
- Red

[Labromaniac]

Thanks. I don't need to change it. I traditionally sleep from 10pm to 6am so the default settings are OK for me as far as the time frame is concerned.