[Prevention of postoperative thrombo-embolic accidents following thoracic surgery by low-dose calcium heparinate: a comparative study (author's transl)].

A comparative clinical trial was undertaken in 2420 patients undergoing thoracic surgery during a 4-year period (1973-1977); 40% of the patients had bronchial cancer. Random allocation was not considered as being possible by the surgeons and was replaced by allocation according to the time of operation. There were three protocol groups: Protocol A: First morning operations (1007 patients): subcutaneous calcium heparin, 5000 units (Ul) 2 hours and 30 minutes before surgery then every 12 hours for 15 days. Protocol B: Second morning operations (932 patients): same dose and duration of treatment; the first injection took place 24 to 72 hours after the surgical procedure. The doses were increased from the fourth day after surgery in order to obtain a moderately prolonged partial thromboplastin time (difference patient-control: 7 to 14 seconds). Protocol 0: 481 patients received no anticoagulant treatment because of a contraindication or minor surgical procedure. Preliminary results showed and increase of per-operative bleeding (p less than 0.01) in treated patients; this was very well accepted by the surgeons. Among the heparin-treated patients, 11 pulmonary emboli out of 13 were observed in patients with bronchial cancer. Of these 13, 10 were fatal with 9 being verified at autopsy. The pulmonary emboli episodes occurred significantly earlier in protocol B than in protocol A. Fatal pulmonary embolism in patients with bronchial cancer was significantly more frequent in protocol B (7 cases) than in protocol A (1 case); P less than 0.01. These results have shown a low frequency of fatal pulmonary emboli in patients without bronchial cancer receiving twice-daily subcutaneous injections of heparin (2 of 1102 operated subjects). The rate was higher in patients with bronchial cancer and this results supports a recommended thrice-daily dose in such patients. In addition, the pre-operative administration of heparin is useful in preventing early post-operative pulmonary embolism.