Hello Guest, Welcome to Apnea Board !
As a guest, you are limited to certain areas of the board and there are some features you can't use.
To post a message, you must create a free account using a valid email address.

or Create an Account


New Posts   Today's Posts

Faking SpO2 data so that AirSense thinks that it recorded it?
#1
Faking SpO2 data so that AirSense thinks that it recorded it?
Edited to say that AFTER I posted this I saw bollar's thread, which makes all of this moot -- it appears that OSCAR doesn't know how to read SAD files yet, as there are only about 3 people who can afford the setup, LOL. But maybe this is a good idea for the purposes of faking things?

http://www.apneaboard.com/forums/Thread-...d-Oximeter


Ok, like every software idea that comes from the "a little knowledge is a dangerous thing" corner, this is either laughably stupid, or kind of clever. This is specifically a question for whomever are the resident OSCAR experts on the file/data structure of ResMed SD cards and/or pulse-oximetry data.

I know that the Air10 has a plug-in port for a pulse oximeter -- actually I think there's a controller module that plugs into the port behind the door in front of where the filter goes, and then a pulse oximeter plugs into that. And I know that the controller and the pulse-ox are designed for institutional use (patient after patient in a hospital, and DMEs renting them out to different patients for short periods of time, etc.) and are hardened for that use and quite expensive.

I'm speculating that when you plug in the (expensive) ResMed controller/pulse-ox and use it, the machine writes the data out to the SD card? So you end up with the pulse-ox data being additional channels in the data stream? Looking at a day's DATALOG files

Code:
% ls -ltR ./DATALOG/20210712
total 6816
-rwxrwxrwx  1 cathy  staff        8 Jul 13 06:32 20210713_004725_PLD.crc
-rwxrwxrwx  1 cathy  staff   273630 Jul 13 06:32 20210713_004725_PLD.edf
-rwxrwxrwx  1 cathy  staff        8 Jul 13 06:32 20210713_004725_SAD.crc
-rwxrwxrwx  1 cathy  staff    84514 Jul 13 06:32 20210713_004725_SAD.edf
-rwxrwxrwx  1 cathy  staff        8 Jul 13 06:32 20210713_004724_BRP.crc
-rwxrwxrwx  1 cathy  staff  3106970 Jul 13 06:32 20210713_004724_BRP.edf
-rwxrwxrwx  1 cathy  staff        8 Jul 13 05:41 20210713_004715_EVE.crc
-rwxrwxrwx  1 cathy  staff     1168 Jul 13 05:41 20210713_004715_EVE.edf


it looks like the *_SAD.edf is the intended place to put that data?

Quote:% more 20210713_004725_SAD.edf

0       X X X X DCBD C580                                                               Startdate 13-JUL-2021 X X X SRN=23191671673  MID=36  VID=9                      13.07.2100.47.261024    EDF                                         345     60.00   3   Pulse.1s        SpO2.1s         Crc16                                                                                                                                                                                                                                                           bpm     %               18.00   0.00    -32768  300.00  100.00  32767   18      0       -32768  300     100     32767                                                                                                                                                                                                                                                   60      60      1                                                                                

So here's my question... Does OSCAR know how to take data loaded in from the Oxymetry Wizard (coming from all of the various and sundry formats that OSCAR supports) and write it back out into ResMed's *_SAD.edf file?

Where I'm going -- is it possible to create a new data directory which is a copy of my ResMed machine card, and transplant all of the *_SAD.edf files with files that contain the data from my (cheap) Contec pulse-ox, write that directory tree out to a new SD card, which I take with me to my sleep doctor, and then they can see my pulse-ox data in the (inferior to OSCAR) ResMed tool that they use?

I'm also wondering if the *_SAD.crc files are Cyclic Redundancy Check files on the *_SAD.edf files, and so if that's not also doctored up then it will be obvious that the data is not the original. Meaning that if the ResMed tool is all snooty about the CRC, that would raise the level of difficulty some more.
Post Reply Post Reply






Donate to Apnea Board  
#2
RE: Faking SpO2 data so that AirSense thinks that it recorded it?
(07-16-2021, 10:54 AM)cathyf Wrote: So here's my question... Does OSCAR know how to take data loaded in from the Oxymetry Wizard (coming from all of the various and sundry formats that OSCAR supports) and write it back out into ResMed's *_SAD.edf file?

No.

Quote:Where I'm going -- is it possible to create a new data directory which is a copy of my ResMed machine card, and transplant all of the *_SAD.edf files with files that contain the data from my (cheap) Contec pulse-ox, write that directory tree out to a new SD card, which I take with me to my sleep doctor, and then they can see my pulse-ox data in the (inferior to OSCAR) ResMed tool that they use?

While you could write files in EDF format, there would be nasty time synchronization problems to resolve, if it were even possible. And, or course, SAD files are used only for ResMed machines and creating this for any other manufacturer's machine would not be useful.

Quote:I'm also wondering if the *_SAD.crc files are Cyclic Redundancy Check files on the *_SAD.edf files, and so if that's not also doctored up then it will be obvious that the data is not the original. Meaning that if the ResMed tool is all snooty about the CRC, that would raise the level of difficulty some more.

Yes, the ResMed tool (ResScan) is very "snooty" about the CRC data being right. It will refuse to read the data card if the CRC values are not correct.

Also, as a general guideline, we don't want to create pseudo SD data cards.
Useful links
Download OSCAR (current version is 1.2.0)
Best way to organize charts
How to attach charts to your post

Membership in the Advisory Members group does not imply medical expertise or qualification for advising Sleep Apnea patients concerning their treatment.
Post Reply Post Reply
#3
RE: Faking SpO2 data so that AirSense thinks that it recorded it?
Aside from those points, OSCAR really does know how to read and display the SAD files. It's just that, for historical reasons unknown to the current developers,, the three items that the OP mentioned were left out when the other oximetry devices were added to SleepyHead.
Apnea Board Monitors are members who help oversee the smooth functioning of the Board. They are also members of the Advisory Committee which helps shape Apnea Board's rules & policies. Membership in the Advisory Members group does not imply medical expertise or qualification for advising Sleep Apnea patients concerning their treatment.
Post Reply Post Reply


Possibly Related Threads...
Thread Author Replies Views Last Post
  Data handling for VERY low SpO2 reading on Viatom product. Ratchick 19 201 09-15-2021, 06:35 PM
Last Post: Crimson Nape
  Importing data from Wellue O2 Ring SPO2 ar3thur 4 984 08-09-2021, 07:02 PM
Last Post: NelsonM
  OSCAR stopped importing graph data on change from S9 to Airsense 10 machine pjfollyfarm 2 152 07-30-2021, 09:14 AM
Last Post: GuyScharf
Idea CMS50D+ Add date and time to SPO2 file adrinef 32 7,557 06-21-2021, 10:36 AM
Last Post: adrinef
  OSCAR preferences for flagging HR & SpO2 events? cathyf 5 128 06-20-2021, 03:08 AM
Last Post: Ratchick
  Bug: Viatom data reappearing in OSCAR after deleting oximetry data Ratchick 2 208 04-19-2021, 10:10 PM
Last Post: Ratchick
Smile SPO2 - What is Data Joint and what is the difference between a 1-Day and 2-Day Joint? jobtimate 1 194 03-21-2021, 04:39 PM
Last Post: pholynyk


New Posts   Today's Posts






About Apnea Board

Apnea Board is an educational web site designed to empower Sleep Apnea patients.