Read, read, read, and then read. Read every book you can get your hands on...LITERALLY. They don't care about fluff, they want to see you are motivated to be the best that YOU can be. They aren't going to take someone who isn't a master of the ICU they wrok in, to try to teach them to be a master at something much more difficult. If you work in a micu...better be able to talk about sepsis/vent settings/antibiotics backward and forward. If you work in a CVICU, you better be able to explain every hemodynamic value/every cardiac med/every sign of post surgical complication/etc. If you haven't put the work in to be the best ICU RN you can be, what reason do they have to think you will put in the work to be the best CRNA you can be?