Nitroglycerin versus epoprostenol: Effects on hemodynamics, oxygen delivery, and hepatic venous oxygenation after liver transplantation

Our objective was to determine the effects of vasodilatory treatment with epoprostenol (PGI₂) and nitroglycerin (NTG) on systemic oxygen delivery index (DO₂) and hepatic venous oxygen saturation (SvhO₂) after liver transplantation. This prospective study used repeated-measures design. Fifteen adult patients undergoing orthotopic liver transplantation (OLT) were enrolled. Postoperatively, a fiberoptic pulmonary artery catheter was inserted into the right hepatic vein and a timed infusion of PGI₂ and NTG was sequentially performed in random order at the following rates: PGI₂ at 5 ng/kg/minute and NTG at 0.1 μg/kg/ minute. Each step in each sequence lasted 45 minutes, followed by a control interval of 45 minutes. Measurements were taken at the end of each period when hemodynamic function was stable. Systemic hemodynamics, DO₂, oxygen uptake index (VO₂), mixed venous oxygen saturation (SvO₂), and SvhO₂ were assessed. We found that PGI₂ induced an increase of cardiac index (+18%, p < .05); DO₂ (+16%, p < .05); and SvhO₂ (+11%, p < .05). Mean arterial pressure was decreased during PGI₂ infusion (−9%, p < .05), as well as during infusion of NTG (−10%, p < .05). NTG significantly decreased DO₂ (−6%, p < .05) and SvhO₂ (−4%, p < .05). Neither drug affected VO₂. We conclude that PGI₂ induced vasodilation and increased systemic oxygen delivery in parallel with SvhO₂, suggesting a corresponding increase of hepatic oxygen supply. NTG induced systemic vasodilation and significantly impaired hepatic venous oxygen saturation and DO₂. Thus, if vasodilatory therapy is indicated in the patient after liver transplantation, PGI₂ appears to be better than NTG in improving DO₂ without impairing splanchnic oxygenation. Copyright © 1996 by the American Association for the Study of Liver Diseases.