A 58-year-old woman is awaiting orthotopic liver transplantation for primary biliary cirrhosis in the ICU. An oximetric pulmonary artery catheter is placed and an SVO2 of 90% is measured. Which of the following blood pressure interventions is the LEAST appropriate for treatment of hypotension in this patient?

A 58-year-old woman is awaiting orthotopic liver transplantation for primary biliary cirrhosis in the ICU. An oximetric pulmonary artery catheter is placed and an SVO2 of 90% is measured. Which of the following blood pressure interventions is the LEAST appropriate for treatment of hypotension in this patient?

• A. Milrinone
• B. Norepinephrine
• C. Vasopressin
• D. Phenylephrine

Answer: (A)

High mixed venous oxygen saturation indicates that oxygen delivery exceeds tissue extraction, so the hypotension here is more consistent with vasodilation and reduced systemic vascular resistance than with low cardiac output. In this vasodilatory state, you want agents that raise vascular tone and blood pressure. Milrinone is a phosphodiesterase-3 inhibitor that increases inotropy but also causes vasodilation, which lowers systemic vascular resistance and can worsen blood pressure when the problem is vasodilation rather than pump failure. Therefore it is the least appropriate choice for treating hypotension in this context. Norepinephrine, vasopressin, and phenylephrine all constrict vessels and raise mean arterial pressure, aligning with the need to counteract vasodilation and maintain organ perfusion in this patient.

High mixed venous oxygen saturation indicates that oxygen delivery exceeds tissue extraction, so the hypotension here is more consistent with vasodilation and reduced systemic vascular resistance than with low cardiac output. In this vasodilatory state, you want agents that raise vascular tone and blood pressure. Milrinone is a phosphodiesterase-3 inhibitor that increases inotropy but also causes vasodilation, which lowers systemic vascular resistance and can worsen blood pressure when the problem is vasodilation rather than pump failure. Therefore it is the least appropriate choice for treating hypotension in this context. Norepinephrine, vasopressin, and phenylephrine all constrict vessels and raise mean arterial pressure, aligning with the need to counteract vasodilation and maintain organ perfusion in this patient.