Portohepatic Pressures, Hepatic Function, and Blood Gases in the Combination of Nitroglycerin and Vasopressin: Search for Additive Effects in Cirrhotic Portal Hypertension

We studied the effects of the combination of nitroglycerin and vasopressin on portohepatic hemodynamics, hepatic function, and blood gases in nine patients with cirrhosis and portal hypertension. Vasopressin infusion at a dose of 0.4 U/min caused a significant fall in portal pressure, which is evaluated by portal venous pressure gradient (-34%, p less than 0.01), associated with a decrease in hepatic perfusion (-33%, p less than 0.01) and intrinsic clearance (-20%, p less than 0.01) after 30 min. The arterial oxygenation, however, was not modified (paO2; from 73 +/- 8 to 72 +/- 7 mm Hg, NS). Nitroglycerin infusion at a dose of 100 micrograms/min was then administered for 20 min. The addition of nitroglycerin produced a further reduction in free portal venous pressure (-12%, p less than 0.01), but this was not associated with a significant improvement in both hepatic perfusion (+16%, NS) and intrinsic clearance (-7%, NS). In addition, there was a significant fall in arterial oxygenation (paO2; from 72 +/- 7 to 59 +/- 5 mm Hg, p less than 0.01). We conclude that the addition of nitroglycerin to vasopressin has a beneficial effect on free portal venous pressure, but does not have hepatic benefit. Moreover, sufficient care must be taken, when treating portal hypertension with this combination, to avoid arterial hypoxemia.