Effect of prostaglandin E1 and nitroglycerin on portal venous flow during hypothermic extracorporeal circulation: Assessment by transesophageal echography

Background: Although several vasodilators are used to control vascular resistance during cardiac surgery, their effects on splanchnic circulation during extracorporeal circulation are unknown. We designed the present noninvasive study to evaluate the effect of prostaglandin E1 and nitroglycerin on portal venous flow during extracorporeal circulation using transesophageal echography. Methods: We included 26 patients undergoing cardiac surgery with moderate hypothermic extracorporeal circulation in this study. After obtaining hemodynamic stability under extracorporeal circulation, we measured portal venous diameter, mean flow velocity and the velocity time integral using transesophageal echography and calculated portal venous flow. The patients were assigned to two groups where either prostaglandin E1 (N=13) or nitroglycerin (N=13) was administered intravenously to maintain perfusion pressure at the level of 70 mmHg. We measured the same parameters 20 and 40 min following administration of the drug. Results: Visualization of the portal vein was obtained by transesophageal echography in anesthetized patients. Calculated portal venous flow significantly increased in the prostaglandin E1 group, while it did not alter in the nitroglycerin group. Conclusion: The present results indicate that transesophageal echography may be a feasible toot to assess portal venous flow, and that prostaglandin E1 may improve the blood distribution to the splanchnic area and the liver during hypothermic extracorporeal circulation.