Markers of splanchnic perfusion and intestinal translocation of endotoxins during cardiopulmonary bypass: Effects of dopamine and milrinone

Abstract

Objectives: To investigate markers of splanchnic perfusion and the extent of endotoxemia during cardiopulmonary bypass (CPB) and to compare the effects of dopamine and milrinone on both splanchnic perfusion and endotoxemia. Design: Prospective, randomized, blinded study. Setting: University teaching hospital. Participants: Twenty-four patients scheduled for elective coronary artery bypass graft surgery (CABG). Interventions: Patients were allocated to receive placebo (eight patients), dopamine (eight patients), or milrinone (eight patients) during CPB, and at seven times intraoperatively assays were performed of arterial and hepatic venous endotoxin levels, as well as measurements and/or calculations of intramucosal gastric pH (pHi), arterial and hepatic venous lactate-pyruvate ratio (lac/pyr), and hepatic venous oxygen saturation (S HVO 2). Measurements and Main Results: Both splanchnic and systemic endotoxin levels increased significantly, and this was unaffected by either dopamine or milrinone. Gastric pHi did not change, and there were only modest increases in lac/pyr, which remained within the normal range of less than 10 in both splanchnic and systemic blood. In the placebo group, S HVO 2 decreased at the onset of CPB and also significantly decreased during rewarming and at the end of CPB and surgery. In the dopamine-treated patients, S HVO 2 was greater compared with placebo and milrinone during both hypothermic and rewarming phases. Conclusion: Endotoxemia occurs during routine CPB. Neither pHi nor lac/pyr values showed adverse change, but hepatic venous oximetry may be a more sensitive indicator of splanchnic dysoxia in that S HVO 2 was reduced during rewarming. Whether dopamine or milrinone confer protection against splanchnic ischemia remains uncertain.