Autonomic Pharmacology USMLE Step 1 Practice Question

A 74-year-old man is brought to the intensive care unit following emergency exploratory laparotomy for perforated diverticulitis with fecal peritonitis. He has a history of hypertension and type 2 diabetes mellitus. Despite receiving 3 liters of intravenous crystalloid resuscitation over the past two hours, he remains hemodynamically unstable. His temperature is 39.4°C, heart rate is 118 beats per minute, respiratory rate is 24 breaths per minute, and mean arterial pressure is 52 mm Hg. Laboratory studies reveal a lactate of 4.8 mmol/L, white blood cell count of 22,000/µL, and creatinine of 2.1 mg/dL. Physical examination demonstrates warm, flushed extremities with bounding pulses consistent with distributive shock physiology. A vasopressor is chosen that increases vascular tone predominantly through alpha-1 adrenergic receptor stimulation while also supporting cardiac contractility through beta-1 adrenergic receptor stimulation. Which of the following agents is most appropriate?