Prophylaxis of venous thrombosis after major thoracic surgery.

The high incidence (50-60%) of deep venous thrombosis of the legs (DVT) after major thoracic surgery is reduced only by about half with routine low-dose heparin prophylaxis. The present study compared the efficacy of a higher dose of heparin (7500 U twice daily) with the commonly used dose of 5000 U twice daily in preventing scan-detected DVT in 100 consecutive patients having thoracotomy for carcinoma of the lung or oesophagus. After the higher dose of heparin, postoperative DVT was not significantly less frequent (22% compared with 33% for total DVT) but was significantly less extensive (8% and 14%, respectively, for bilateral calf DVT, and 0% and 4% for popliteal DVT). Despite prophylaxis, DVT was especially common after oesophagogastrectomy (41% total DVT, 30% extensive DVT). No excessive postoperative bleeding was noted in either group. It is concluded that an increased dose of heparin safely offers increased prophylaxis against DVT in patients undergoing major thoracic surgery for cancer.