I loved the trauma/surgical ICU as a med student and resident. Those patients challenge you like no others will, helping you develop critical thinking skills for the rest of your training and career. You'll be a stronger intern/resident too for having done ICU first.
I agree with everything ArmyTiger said. My own thoughts:
#1 - Listen to the nurses, especially the more seasoned ones. They know you don't know **** and can run circles around you with their knowledge and experience. If an ICU nurse thinks something is wrong with a patient, don't blow them off. Even if you have no clue, go see the patient and start to troubleshoot the issue. ICU nurses appreciate docs who listen to them and take their concerns seriously. In turn, they'll start to look out for you and will help your rotation go a lot smoother.
#2 - Learn to be systematic in your assessments of ICU patients. Review the trends in vitals and I/Os constantly. Review medications everyday and decide what stays, goes, or needs to be added. Develop your plan by systems: cardiac, pulmonary, GI, renal, etc. Your focus on an ICU patient is often directed at addressing one system in particular, e.g. weaning pressors, moving toward extubation, advancing feeds, initiating dialysis, etc. What is it you can do for them today to make them better than they were when your day started?
#3 - Become a line master. Take every opportunity you can to put in central lines, dialysis catheters, and A-lines. Learn how to put central lines in the IJ, subclavian, and femoral positions. For A-lines, learn how to do radials, femorals, and DPs (brachials as well if your institution allows).
#4 - Never be afraid to ask for help from your seniors. They've been where you are and know you'll need help. There's a good chance they may even hang around the ICU early in the year to keep an eye on you anyway or chat up the nurses since you tend to develop some of the closest relationships with ICU nurses during residency.
#5 - Help each other out. I don't know what your call situation will be like, but help take care of most of the work during the day for the overnight/weekend person. Nobody wants to be dumped on at 5 PM signout that 3 patients needs CT scan escorts, 5 people need new lines, or H&Ps aren't done for the new admissions.
#6 - Learn how to have tough talks with patients' families. Having a family member in the ICU can be a life altering event in a family's life. Take time to speak with family members about their loved one's condition and the plan of care. Address their questions to the best of your ability, but don't make stuff up if you don't know the answer. Sit in on family conferences with your attendings and listen to the language they use when talking about issues like withdrawing care, worsening conditions, chances of survival, etc.
#7 - Take care of yourself. Eat and drink when you can. If it's the overnight and nothings happening, tell the nurses you're going to lay down for a nap and to call/page if there's a problem.
#8 - Constantly round. Keep checking up on every patient assigned to you. Are your interventions working? Do you need to do something different or let it ride? Walk the unit and learn to develop your gestalt for the ICU patient. Eventually, you should just be able to look in their room and get an immediate sense of how they're doing and what needs to be done. ICU attendings typically have that skill down pat.
#9 - Review everybody's films. Typical ICU rounds include looking at CXRs for everyone on a vent or CTs for possible infectious sources. But remember, these are the sickest of the sick patients with lots of interesting pathologies. Review their presenting images and take every opportunity to ask questions from your seniors and attendings on reading films. It's an invaluable skill for every general surgery resident.
I could go on, but these are the most pertinent things that come to mind to survive and thrive in your ICU rotation.
