Prophylaxis of early post-operative deep venous thrombosis by monitored heparin infusion

Increases in whole blood coagulability in patients undergoing abdominal surgery have been measured with the thrombelastograph. A continuous, low dose intravenous infusion of heparin has been administered in the operative period in an attempt to control these coagulability increases without increasing the risk of haemorrhage. A preliminary sub-cutaneous dose of heparin followed by a continuous infusion throughout the operation and for two hours afterwards effectively prevented the expected coagulability increase and resulted in reduction of early deep venous thrombosis incidence from 9/20 in controls to 1/19 in treated patients (p less than 0.05). The infusion has also been used in conjunction with a pre-operative test to predict the risk of deep venous thrombosis. Of 20 patients examined, 11 were designated as high risk and received an intra-operative heparin infusion and 9 predicted low risk patients received no specific prophylaxis. No venous thrombosis occurred in any patient within 48 hours of surgery.