Seeking Tweaking Advice-ResScan

NateS wrote:idamtnboy, I have sent you a pm with a link to what should be the BRP.edf for the sleep session of Feb. 4th, from about 2AM to 11:30AM with an AHI of 6.54. I had 32 hypopneas and 29 apneas.

Thanks. I looked at it with EDF browser, but by itself it's hard to see the apneas. Plus the curves just don't look the same in EDF Browser and Resscan because of scale differences. So, if you would please upload the corresponding PLD, SAD, and EVE files, both the edf and crc. Also, upload the STR file that covers that same period. I'd try to use the STR you already sent but I need the crc and edf pair. If the crc and edf files don't correspond Resscan won't open them. I think with those files I can create a sufficiently complete set of files, using my ID and machine data to create a fake file set, to get Resscan to open it up. If not, I'll let you know!

idamtnboy wrote: Thanks. I looked at it with EDF browser, but by itself it's hard to see the apneas. Plus the curves just don't look the same in EDF Browser and Resscan because of scale differences. So, if you would please upload the corresponding PLD, SAD, and EVE files, both the edf and crc. Also, upload the STR file that covers that same period. I'd try to use the STR you already sent but I need the crc and edf pair. If the crc and edf files don't correspond Resscan won't open them. I think with those files I can create a sufficiently complete set of files, using my ID and machine data to create a fake file set, to get Resscan to open it up. If not, I'll let you know!

idamtnboy,

As you suggested/requested, I have sent you a pm with a link to a zipped package of said files:

http://dl.dropbox.com/u/12319630/fr%20ResScan.zip

Regards, Nate



Subject: Seeking Tweaking Advice-ResScan

I think I've got it figured out. It's the absence of FOT. Resmed uses what they call forced oscillation technique (FOT) to determine if an apnea is an obstructive or central apnea. I do not see that signal in the Adapt flow graph. You can clearly see the FOT signal on my CA and OA graph segments below but not in the Apnea graph segment from your data. The second set of pics with '2' in the name are the same as the first three except zoomed in quite a bit more. The graph segments for the OA and CA may not be the exact same event. I copied and recopied the graph segments 2 or 3 times to get the same scales on them and switched back and forth between your graph and mine.

It's a good thing you included the identification files in the zip. Resscan wouldn't read your data with my identification files on the card!

If you can't see the whole picture use your browser zoom feature, Control + and Control - in Firefox.

CA with FOT Autoset


OA with FOT Autoset


Apnea VPAP Adapt


CA with FOT 2 Autoset


OA with FOT 2 Autoset


Apnea 2 VPAP Adapt

Why Resmed doesn't use the FOT with the Adapt I don't know. I may be related to the fact the Adapt is constantly varying the pressure and flow to mimic the user's natural breathing pattern and FOT just won't work on top of that. Or maybe it just complicates the control and response of the blower to the extent it's not sufficiently reliable. In that paper I linked to earlier they stake a lot of their reputation on the confidence one can place into the FOT algorithm.

A Google search may find a document on their website related to ASV and FOT, but I have my doubts. I didn't find one the other night when I searched.

idamtnboy wrote:Why Resmed doesn't use the FOT with the Adapt I don't know. I may be related to the fact the Adapt is constantly varying the pressure and flow to mimic the user's natural breathing pattern and FOT just won't work on top of that. Or maybe it just complicates the control and response of the blower to the extent it's not sufficiently reliable. In that paper I linked to earlier they stake a lot of their reputation on the confidence one can place into the FOT algorithm.

A Google search may find a document on their website related to ASV and FOT, but I have my doubts. I didn't find one the other night when I searched.

idamtnboy, What you have done to reconstruct this data search and comparison is absolutely amazing!

Naturally, I'm disappointed but at least convinced that the distinction between central and obstructives is simply not produced and recorded/reported on the ASV!

Thanks so much for all your hard work!

You have made this very interesting and educational for me, and your demonstrated skills are astonishing!

I am sending you a pm on a related matter.

Thanks so much!

Nate

NateS wrote:Thanks so much for all your hard work!

You're welcome. It was an interesting challenge I just couldn't ignore!