The influence of propofol and midazolam/halothane anesthesia on hepatic S(v)over-barO2 and gastric mucosal pH during cardiopulmonary bypass

Objective: Because propofol is known to reduce vascular resistance, the objective of this study was to compare the indices of hepatosplanchnic circulation and oxygenation during cardiopulmonary bypass (CPB) in patients anesthetized with either propofol or midazolam/halothane. Design: A prospective, randomized, nonblinded study. Setting: A university hospital. Participants: Twenty patients undergoing cardiac surgery with CPB. Interventions: Nine patients were anesthetized with propofol/fentanyl/pancuronium and 11 patients were anesthetized with midazolam/halothane/fentanyl/pancuronium All patients had a nasogastric tonometer tube and two fiberoptic thermodilution catheters inserted; one in the pulmonary artery and one in the upper right hepatic vein. During bypass, S (v) over bar O(2)s were measured from the venous line of the heart-lung machine. Measurements and Main Results: Gastric mucosal pH (pHi) was measured prebypass, 30 minutes after the start of CPB, and just before weaning oft CPB. Hepatic S (v) over bar O-2 (HS (v) over bar O-2) values were recorded every 5 minutes. The pH gap was less at 30 minutes of hypothermic CPB in the propofol group. In the midazolam/halothane group, the HS (v) over bar O-2 decreased after the start of rewarming, whereas in the propofol group the values remained almost at the prebypass levels. At the end of rewarming, the HS (v) over bar O-2 was almost identical in the two groups. Conclusion: Propofol preserved the HS (v) over bar O-2 during CPB and produced a more optimal relationship between the hepatosplanchnic blood flow and oxygen consumption. Copyright (C) 1998 by W.B. Saunders Company.