Hepatic blood flow in humans during isoflurane-N2O and halothane-N2O anesthesia

Hepatic blood flow (HBF) (assessed by plasma clearance and hepatic extraction of indocyanine green), cardiac index, and hepatic venous oxygen saturation were measured in patients before and after induction of anesthesia with thiopental, fentanyl, and N2O, and again during halothane (1 MAC)-N2O (n = 5) or isoflurane (1 MAC)-N2O (n = 6) anesthesia before the start of surgery. Induction of anesthesia decreased HBF and cardiac index. Before administration of volatile anesthetics, both groups had similar values of HBF, cardiac index, and hepatic venous oxygen saturation. During anesthesia cardiac index remained stable in both groups, whereas HBF increased significantly with isoflurane but did not change significantly with halothane. Hepatic venous oxygen saturation was also significantly greater during isoflurane than during halothane anesthesia. We conclude that isoflurane increases HBF in anesthetized patients and is associated with a higher hepatic venous oxygen saturation than is halothane.