[The hemodynamic and metabolic changes following tourniquet release during halothane anesthesia]

We measured the hemodynamic and metabolic changes following the release of lower limb tourniquet during halothane anesthesia, and discussed the cause of reduction in the blood pressure and the effective method for prevention. Cardiac index decreased transiently following the release, and gradually increased afterward. Systemic vascular resistance index decreased continuously and progressively until 10 minutes after the release. These results indicate that the causative factors of reduction in the blood pressure are temporary decrease in cardiac output and subsequent decrease in systemic vascular resistance. In mixed venous blood, pH decreased, PCO2 increased and HCO3- remained unchanged after the release. It seems that pH reduction was chiefly caused by the increase in PO2. Thus, the preventive method for reduction in the blood pressure following the tourniquet release may be as follows; 1) intravenous fluid loading, 2) hyperventilation, 3) elevation of lower limb, 4) lightning the anesthesia, and 5) finally giving vasopressors.