RE: Resscan 4.3 Export to .CSV
I have a ResMed S9 AutoSet and this is what I've been able to find out so far about the sleep session data on the SD Card. Hopefully this is not too long winded.
The .edf files in the DATALOG directory are data files in the open format, European Data Format (edf), you can find out more about the open format by searching "edf file format" in your favorite search engine and looking at the edfplus info site.
There are 8 daily files added to my SD Card, 4 of which are .crc and I believe they are cyclic redundancy check (crc) files used to verify that the data is not corrupt on the SD Card.
A very simplistic view of a CRC is adding up all the values in the data file and saving the lower bits as a value and using this number to check the file data at the next use. If the CRC does not add up to the same number there is an error in the data. There is lots of info on the web for those that are interested in more detail.
The other 4 are the files with the good stuff. The filename format is something like:
YYYYMMDD_HHMMSS_PLD.edf (a real file name 20131127_234148_PLD.edf)
The four files of interest end with:
_BRP.edf, _EVE.edf, _PLD.edf and _SAD.edf
The _BRP.edf file is the high data sample rate, 25Hz (0.04 second/sample), data file that has the FLOW data and the MASK PRESSURE data in it.
The _EVE.edf file is the event data file and is a non-contiguous file, meaning that the data is placed in it as it happens and not necessarily in a continuous form. For example, if the patient has an apnea at midnight and then another one at 4AM there is no data for the in between times. To use this file with EDFBrowser a conversion needs to be made to make it a contiguous data file and the EDFBrowser has the converter to do it.
The _PLD.edf file is the low data sample rate file, 0.5Hz (2 seconds/sample) and contains the MASK PRESSURE, THERAPY PRESSUR (file spec only allows for 15 characters in a label), EXPiration PRESSURE, LEAK rate, RR or respiration rate, Vt or tidal volume, MV or minute volume, which is an average volume over a minute, SNORE INDEX which is a calculated indicator of the level of snoring based on the pressure wave sent back up the tube during a snoring event, FFL INDEX or free flow index which is an indicator on how open or close the air way is during an event. There are also two other un-labeled signals, 10 and 11, that I have yet figured out what they are about.
The _SAD.edf is the Oximeter data and only has data if the ResMed (or compatible) Oximeter is hooked up to the S9 (and it is a really expensive option from what I've found)
When I first opened EDFBrowser and loaded files I did not see anything that I was expecting to see, just a few straight lines. If you want to try EDFBrowser the following is a brief primer on the use of EDFBrowser, this just touches the surface of the program but will get the sleep data viewable.
1. Copy some (or all) of the data from your SD Card to a directory on your computer. The data files you are interested in are in the DATALOG subdirectory on the SD Card.
I recommend that you write protect the SD Card as soon as you take it out of the S9 and you power down the S9 before you remove the card. I was initially unplugging the S9 but now I press and hold the power button until the system turns off. Place the SD Card in the computer system using what ever adaptor you may need to read an SD Card. Some systems have an SD Card reader built in and some use an SD Card to USB adapter (this is what I use).
2. Unmount or eject the S9 SD Card from the computer system, un-write protect it and place it back in the S9 and turn the S9 back on. The S9 should power up and show a “reading SD Card” message.
3. Start up EDFBrowser.
4. Click on FILE, then OPEN and select one of the data files. For this we will pretend you selected the data file that ends in _BRP.edf. The open file dialog will open and have highlighted two signals, the FLOW and MASK PRESSURE.
5. Click "Add signal(s)" and you will get a gray screen with a couple of blue lines across it.
6. Click FILE, then OPEN again and select the next data file. For this we will pretend you selected the data file that ends in _PLD.edf. The open file dialog will open and have highlighted 11 signals, the MASK PRESSURE, THERAPY PRESSUR,EXP PRESSURE,LEAK,RR,VT,MV,SNORE INDEX,FFL INDEX, 10 and 11.
7. Click "Add signal(s)" and you will get a gray screen with a bunch of additional blue lines across it.
8. Click TIMESCALE and select "Whole recording" in the drop down.
9. Click Amplitude and select "fit in pane" in the drop down.
10. You should see the sleep session displayed. You can hit ctrl+ to expand the time span of the display or ctrl- to compress the time span of the display. A left click and hold with a move up or down on the signal label will change the offset and right click and hold and a move up or down will change the amplitude of the signal. A single left click without the hold will open up a dialog that allows a bunch of other operations on the data. You can use the arrow keys to move the display left and right to show times before or after the view area. You can also us the thumb wheel (if you have one) on your mouse to scroll the time span displayed.
11. If you want to see the event data over top of the sleep data you need to first convert the non-contiguous data in the _EVE.edf file to contiguous data. This is done using the TOOLS menu and selecting "Convert EDF+D to EDF+C" and then select the _EVE.edf file. This operation adds a new file of the same name with EVE_0001.edf after the conversion. Example conversion of 20131127_234148_EVE.edf adds 20131127_234148_EVE_0001.edf, the original file remains unchanged.
12. Click FILE, then OPEN again and select the event data file. For this we will pretend you selected the data file that ends in _EVE_0001.edf. The open file dialog will open and not have any highlighted signals, click close and the event data is now displayed.
Keep in mind that the EDFBrowser displays data by default in a absolute time sequential method so if you select a file that is not from the same sleep session, say the previous day, the data will be there but will not be displayed on the same page. To see the data you need to press ctrl- to increase the time span shown.