You would probably be better off w/ a laminated card in your wallet w/ any pertinent info - medical conditions, allergies, current medications, name/number of your PCP/Doc - These are the items I'd want to know right off when an EMT/Medic brings you in (If I needed more info, I'd get your Doc on the phone from the ED) You should be able to put that on a business-sized card & keep it w/ your ID.

Accessing a USB drive, while possible, probably not terribly practical or probable in an emergency setting.

Sam