In the United States, the term anesthesiologist refers to a physician who completed an accredited residency program in anesthesiology, usually four years following medical school either with M.D. or D.O. degree. In contrast, the term anesthetist is used for nurse anesthesia providers who have undergone specialized training in anesthesia.

Anesthesiologists are physicians who provide medical care to patients in a wide variety of (usually acute) situations. This includes preoperative evaluation, consultation with the surgical team, creation of a plan for the anesthesia tailored to each individual patient, airway management, intraoperative life support and provision of pain control, intraoperative diagnostic stabilization, proper post-operative management of patients.

Outside the operating room, anesthesiologists/anesthesists spectrum of action includes with intrahospitalar or extrahospitalar emergencies, intensive care units, acute pain units. Because anesthesiologists are physicians, in contrast to other anesthesia providers, they are able to utilize their extensive knowledge of physiology, pharmacology and diseases to guide their decision making.