Effect of increased concentrations of carbon dioxide during halothane anaesthesia on liver blood flow and hepatic oxygen consumption.

The effects of hypercapnia (during halothane anaesthesia) on the hepatic circulation and hepatic oxygen consumption were investigated in anaesthetized greyhounds. The administration of 1% halothane alone caused significant decreases in both hepatic arterial and portal venous blood flows. Hepatic oxygen consumption did not change significantly. When carbon dioxide was added to the inspired gas mixture during the continued administration of halothane, hepatic arterial blood flow showed a further decrease (P less than 0.01), while portal venous flow increased markedly. This resulted in an overall increase in total liver blood flow. Hepatic oxygen supply increased also. However, hepatic oxygen consumption increased during the periods of hypercapnia. Thus, although the hypercapnia increased the oxygen supply to the liver, there was no improvement in the supply: demand ratio.