Low-dose heparin in thoracic surgery: Effect on blood coagulation and fibrinolysis system

Plasma kallikrein, antithrombin III and antiplasmin were determined with chromogenic methods in 29 patients pre-, per-and post-operativety in a controlled, randomized study. 16 patients received calcium heparin, 5000 IU s.c. every 8 hr for 7 days, the first administration given 2 hr before surgical procedure. 13 control patients received saline. A significant reduction of kallikrein and antiplasmin in per-and post-operative periods was observed in the control patients compared with the heparin-treated patients, while there was a significant reduction of anti-thrombin III in the control patients compared with the treated patients only in the per-operative period. The results obtained suggest that activation of the coagulation and fibrinolysis system occurs in patients undergoing thoracic surgery, and that it is inhibited significantly by calcium heparin prophylaxis.