I just finished an ICU intern program. I recommend getting Critical Care Secrets, a book outlining most aspects of critical care in Q and A format--easy to understand. Also, Pepid or Appocrites or some kind of program for your PDA or Blackberry, so you can carry the info around with you.
Good luck! You'll be fine...and remember, the hospital won't let you go on your own unless they feel confident about your abilities.