The Comparative Effect of Fentanyl and Isoflurane on Splanchnic Perfusion during Cardiac Surgery

Abstract

Background: Splanchnic perfusion derangement commonly occurs during cardiac surgery, while splanchnic ischemia is known to increase morbidity in surgical and critically ill patients. We hypothesized that anesthetic agents may have different effects on splanchnic perfusion during cardiac surgery.Methods: Twenty-four patients undergoing cardiac surgery were randomly divided into fentanyl (n = 12) and isoflurane (n = 12) groups. Gastric intramucosal PrCO2 and pHi were measured using tonometry. Patient temperature was maintained at 28 o C during cardiopulmonary bypass (CPB). Measurements were made at the following times: (1) baseline, after the induction of anesthesia, (2) 30 minutes into CPB, (3) 60 minutes into CPB, (4) at the end of CPB, ( 5) one hour after CPB, and (6) 24 hours after CPB. Statistical analysis was performed using repeated measures of ANOVA and the unpaired t-test.Results: The observed hemodynamic changes were similar in both groups. The pHi decreased significantly during hypothermic CPB and remained in this attenuated state up to 24 hours postoperatively in both groups. The pHi in the isoflurane group began to decrease at 30 minutes after starting CPB while that in the fentanyl group decreased at 60 minutes after starting CPB. The pHi of isoflurane group was significantly lower than that of the fentanyl group during CPB and 1 hour after the end of CPB. However, the pHi at 24 hours after CPB was similar in both groups.Conclusions: We conclude that fentanyl provides more protection from splanchnic ischemic insult than isoflurane during cardiac surgery with hypothermic CPB.