I think something like this has been discussed before on here. I see a few potential problems:
1. Is the data sotred in a propritary format and if so can the app reading it run on anything? I made the mistake of putting a lot of data into a lot of software over the years only to have to retype data over again when a newer version of the software wouldn't import or read the files from the old version (examples are Microsoft Money, Microsoft Access, Microsoft Visio and a bunch of freeware/shareward apps). Does the app to read the data fit on the flash drive, can it run on anything its plugged into so when the Ambulance shows up and one of the EMT's pulls out their old laptop running Windows 98 or Macintoch OS 9 and the app only supports Windows XP. Can you import and export the data to other programs or is the data file readable by other software or do you have to hand key all the data into it.
2. What kind of security is on it to prevent someone from accessing personal information, what kind of personal information does it keep? How do you keep it updated?