[Hepatic circulation and anesthesia].

Abstract

Hepatic artery blood flow changes to buffer portal blood flow alterations, maintaining a constant total hepatic blood flow. Portal blood flow is regulated by preportal organs, such as intestine, pancreas and spleen. The liver plays an important role as a blood reservoir for cardiovascular homeostasis. Hepatic blood volume is mobilized actively to the systemic circulation by sympathetic stimulation. Sinusoid, the specialized capillary of the liver, and Disse's space are separated by endothelial cells, which have numerous fenestrations, allowing effective exchanges of solutes between hepatocytes and blood. Unidirectional blood flow in the acinus causes functional differences of hepatocytes according to the lobular zones. Although the majority of anesthetics decreases liver blood flow in a dose dependent manner, halothane inhibits hepatic arterial buffer response, while isoflurane and narcotics preserve it. Energy depletion, cellular acidosis, alteration of calcium homeostasis and superoxide-induced membrane damage, are all implicated as important factors for ischemia-induced liver injury. A better understanding of ischemia-induced derangements of cell function will lead to more rational preservation of the liver cells in the future.