ハロセン麻酔の循環動態と肝血流に関する実験的研究

The systemic and hepatic circulation dynamics of 20 mongrel dogs were investigated both during and after anesthesia with oxygen and 1% or 2% halothane (OF 1% or OF 2%). A decrease in the systolic force during halothane inhalation was accompanied by contraction of peripheral blood vessels under OF 1%, but was accompanied by dilatation of these vessels under OF 2%. The hepatic arteries were not influenced by the anesthetic depth, while the mesenteric blood vessels contracted under halothane inhalation. The peripheral blood vessels contracted under OF 1% but dilated under OF 2%. As the anesthetic depth increased, first the mesenteric blood flow decreased, followed by a decrease in the hepatic arterial flow proportional to the decrease in the blood pressure. The cardiac output and peripheral vascular resistance were reduced, so that the blood flow was redistributed to the superficial and muscular blood vessels, leaving the organs in a state of hypoxia. As the hepatic arterial blood flow is influenced by the blood pressure, the hepatic circulation becomes unfavorable when the blood pressure drops under halothane inhalation. For this reason, it is important that the blood pressure not be allowed to fall too much during halothane anesthesia. Another problem with halothane anesthesia is that the blood flow to the organs remains reduced for at least 2h after termination of the inhalation, thus subjecting the abdominal organs to hypoxia. This condition may lead to liver damage as a postoperative side effect of halothane anesthesia. This tendency was clearly observed under deep anesthesia, which suggests that deep anesthesia with halothane should be avoided.