Prevention of post-operative venous thromboembolism by a new low molecular weight heparin fraction.

The efficacy of low molecular weight heparin (LMW heparin) was assessed in 550 patients over the age of 40 years, undergoing a variety of elective major surgical procedures. LMW heparin fraction (CY 216, Choay Laboratories, Paris) was used in this study. Each patient received a single injection of 1,850 APTT units of LMW heparin 2 h before surgery, and the same dose was repeated daily for at least 7 days post-operation. Fibrinogen uptake test and ventilation perfusion lung scanning were used to confirm the presence of thromboemboli. Of 501 patients in whom the protocol had been accurately followed, 17 (3.4%) developed DVT, in none were thrombi bilateral. 22 (4.4%) died during the post-operative period. In none of the autopsied patients could emboli be demonstrated. Blood loss during surgery was considered to be excessive in 32 (6.4%). In 19 (3.8%), subcutaneous haematoma developed at the site of abdominal incision. The data presented in this paper indicates that a single daily injection of 1,850 APTT units of LMW heparin is a convenient and safe methods of preventing post-operative venous thromboembolic complications in patients undergoing major abdominal surgery.