Which of the following effects are advantages of combined vasopressin and nitroglycerin intravenous infusion, as compared with vasopressin infusion alone, in controlling acute variceal bleeding?

B. Lower incidence of vasopressin side effects.

C. More effective control of bleeding.

DISCUSSION: Vasopressin acts through vasoconstriction of splanchnic arterioles. Both portal venous inflow and portal venous pressure are reduced, resulting in control of acute variceal bleeding in approximately 50% of patients. However, the adverse side effects of systemic hypertension, bradycardia, decreased cardiac output, and coronary vasoconstriction are quite common during vasopressin infusion. Simultaneous administration of nitroglycerin or nitroprusside eliminates these side effects—and in one controlled trial enhanced therapeutic effectiveness. Although the mechanism of action of this combined infusion is not clear, vasodilation of portal-systemic collaterals, resulting in a further reduction in portal pressure, may be responsible.