The effect of enteral oxygen administration on the hepatic circulation during halothane anaesthesia: experimental investigations.

An investigation of the hepatic microcirculation and oxygen tension in 20 white rats showed that halothane anaesthesia was associated with a reduction in the diameter of the terminal portal venous branches, sinusoids and central veins, and with a decrease in the hepatic oxygen tension from 28.8+/-4.8 to 22.4+/-3.9 mmHg (mean +/-SEM). Enteral oxygen administration was followed by an increased blood flow in all the observed vessels, by an increase in the number of simultaneously filled sinusoids and also by an increase in the hepatic oxygen tension to 35.2+/-10.1 mm Hg. Subsequently, changes in blood flow in the hepatic artery and portal vein were investigated in 10 cats by cineangiography. During inhalation of halothane the hepatic artery blood flow was observed to increase by 30%, while portal vein blood flow was found to decrease by 57% of the initial value. Thus total hepatic blood flow was reduced by 40%, with the ratio of hepatic artery blood flow to total hepatic blood flow increasing from 19% to 43%. When enteral oxygen was administered, the total hepatic blood flow was restored to 92% of the value before anaesthesia. This resulted from an increase in the portal blood flow fraction only. It is concluded that disturbances in the liver circulation in cats and rats produced by halothane anaesthesia can be modified by the simultaneous administration of enteral oxygen.