Effect of Epidural Versus General Anaesthesia on Calf Blood Flow

Abstract

The arterial inflow into the calf, venous emptying rate and venous capacity were studied by venous occlusion plethysmography on the nonoperated leg in 2 groups of patients undergoing total hip replacement. A group of 8 patients received epidural blockade intraoperatively, which was prolonged postoperatively for pain relief; the other group of 8 patients was given general anesthesia with intermittent postive-pressure ventilation intraoperatively and parenteral analgesics for pain relief in the postoperative period. The calf blood flow and venous capacity were lower in patients receiving general anesthesia when measured at the end of surgery and significantly lower in this group when measured 3 h postoperatively. The sustained reduction of flow in the deep veins of the lower limb might be a significant contributory factor in the initiation of deep venous thrombosis. In 3 of the 8 patients in the general anaesthesia group, the venous emptying rate and venous capacity had decreased 3 h postoperatively to a very low level, indicating thrombus formation in immediate association with the surgery.