COMPARATIVE EFFECTS OF HALOTHANE, ISOFLURANE, AND SEVOFLURANE ON THE LIVER WITH HEPATIC-ARTERY LIGATION IN THE BEAGLE

Recently, there has been increasing interest in the alterations in splanchnic and hepatic circulation and preservation of hepatic oxygenation and function during anesthesia and surgery. However, the effects of volatile anesthetics under a condition of marginal hepatic oxygen supply are not well understood. Using a crossover design, we therefore studied the effects of equianesthetic concentrations (1.5 MAC) of halothane, isoflurane, and sevoflurane on hepatic oxygenation and function in nine beagles in which the hepatic artery had been ligated. Portal blood flow was measured by an electromagnetic flow meter. Hepatic function was assessed by indocyanine green elimination kinetics. While cardiac output and mean arterial pressure were greater during halothane anesthesia than during isoflurane and sevoflurane anesthesia, portal blood flow and hepatic oxygen supply were significantly less during halothane and sevoflurane anesthesia than during isoflurane anesthesia. With regard to hepatic oxygen uptake, there was a significant difference between halothane (2.7 +/- 1.2 ml.min-1.100 g-1) and sevoflurane (3.7 +/- 2.0 ml.min-1.100 g-1; P < 0.05). Consequently, the hepatic oxygen supply/uptake ratio and the hemoglobin oxygen saturation and oxygen partial pressure in hepatic venous blood during sevoflurane anesthesia were significantly less than they were with the other anesthetics. Indocyanine green clearance was better preserved during sevoflurane anesthesia (39.7 +/- 12.0 ml.min-1) than during halothane anesthesia (30.9 +/- 8.4 ml.min-1; P < 0.05). We conclude that sevoflurane is accompanied by a smaller oxygen supply/uptake ratio than is halothane and isoflurane, while it preserves hepatic function. We speculate that the difference between sevoflurane and isoflurane may be attributed to sevoflurane's less potent vasodilatory effect on the splanchnic system, and that the difference between sevoflurane and halothane may be attributed to the sevoflurane's weak metabolic depressant effect on the liver.