I work in a CCU. Though CC nurses usually have 1-2 patients, Critical Care Nurses have many functions. Critical thinking is a big one.We look at the entire picture and how everything relates to plan for the best outcome for the patient. We look and intrepret labs and determine whether the dr needs to be called for abnormal values and we take steps to correct the values. If a patients condition is deteiorating we look at the big picture to figure out what is going on and support the patient until problem can be solved. We can order ABGs, CXRs, Labs, etc to try and pinpoint problems based on what we see. Often there are standing orders that we have that can be used based on clinical intrepretation to guide our care (ie: to start vasoactive meds, for pain control, to give blood products, for codes, for extubation procedures, etc). We use technology to assist us in our care (vents, swans, icps, and many other things), We titirate medications that are very potent to manage clinical symptoms and "numbers" obtained from our technology. If the patient is actively trying to die, we take measures to save them the best that we can. On top of all that, we do basic care for the patient, keep them as comfortable as we can, take care of their emotional and spiritual needs and we support the family (which can be a big job in itself, LOL). We are the patient's advocate. We are the ones talking to the families to find out the needs of the patient (if the patient is unable to speak for themselves). We coordinate the patient/family wishes with the plan of care and to the doctor. Many ICUs do not have CNAs, if your patient is vomiting or has frequent BMs, is "crazy" etc, it us up to you to do the cleaning, turning, skin care, baths, feeding, etc. It is a great job, both technical/mechanical but the "basics" are just as important to remember! I am sure that others will have more answers as to what an ICU RN does.