Thromboembolism and Blood Loss: Continuous Epidural Block Versus General Anesthesia with Controlled Ventilation

Continuous epidural block offers advantages over general anesthesia with controlled ventilation by decreasing the frequency of deep venous thrombosis and pulmonary embolism as well as blood loss and transfusion requirements. Hemodynamic differences, with lower mean arterial and pulmonary arterial blood pressures—and consequently less arterial and venous oozing of blood from the surgical wound—in patients given continuous epidural block, probably explain the lower blood loss with this anesthetic technique. The thromboprophylactic effect of continuous epidural block is explained by a hyperkinetic blood flow in the major vessels of the lower limbs. Other factors include less tendency to clotting and better fibrinolysis function with this anesthetic technique. A “stabilizing” effect of local anesthetics on blood cells and endothelial cells is another possible additional explanation. The lower blood transfusion requirements might also play a role.