ER doctors evaluate, treat, and then either discharge or admit each patient who visits the emergency department, from major trauma cases to non-life-threatening, minor injuries. While it's true that practicing emergency medicine requires physicians to hold knowledge and skills that extend across many fields of medicine, from surgery and internal medicine to pediatrics and psychiatry, that doesn't mean an emergency physician is a one-person show. ER doctors spend only about one-quarter of their shift directly with patients; in comparison, nurses spend about 37 percent of their time directly caring for patients [sources: Füchtbauer, Westbrook].
But fictional ER doctors are often seen doing pretty much all the work you'd normally expect to see managed by other members of the emergency medical team. For example, they might insert an IV (usually handled by a nurse), operate specialized equipment such as MRI scanners (usually handled by a technician), and take care of duties that normally fall to nurses, technicians, pharmacists, surgeons and other specialists. It takes an entire team of trained staff to run an ER, but on TV, the docs often seem to handle it all.