wood.... i have a feeling you haven't worked in a hospital yet, so therefore i am going to go easy on you 🙂
anesthesia in the ICU provides ALL critical care coverage: which includes the critical management of ALL issues from Neuro (traumatic brain injury, stroke, hemorrhage, ICP probs), Cardiac (MI, CHF, cardiogenic shock, Arrhythmias), Pulmonary (PE, ARDS, BOOP, pneumonia, etc.), GI (variceal bleeds, etc...), RENAL (ARF, starting/running CVVH, etc..), Infectious (sepsis, antibiotic management, etc.), Nutrition (TPN).... managing post-operative patients, intubating, performing bronchoscopies, some depts do bedside percutaneous tracheostomies, stabilizing patients pre-op (thoraco-abd. aneurysm contained ruptures, etc.)...
so anesthesia does all surgical ICU management if necessary, and some hospital SICUs are Closed-Unit Anesthesia run (ie: MGH).