I had the same reaction when I couldn't find an SD card in my machine. I made an appointment with my sleep doctor (responding to a message from NORCO that said I should see my dr. & take the SD card.
I made the appt. and he was mystified, as my newer machine automatically sends the info so NO SD card required. CHECK your machine's name, Number, etc. against the website specs to see if one is really necessary and check with your sleep dr. to be sure you need an appt., etc.