Early activation of hemostasis during cardiopulmonary bypass: evidence for thrombin mediated hyperfibrinolysis.

In 14 consecutive patients undergoing cardiopulmonary bypass for coronary bypass surgery the time course of coagulation and fibrinolysis markers were measured, e. g. plasma levels of thrombin-antithrombin III (TAT) complexes, cross-linked fibrin degradation products (XIFDP) and plasmin-alpha 2-antiplasmin complexes (PAP). TAT levels exceeded the 90% baseline percentile already during CPB (after opening of aortic clamp) in 10 patients, whereas PAP and XIFDP exceeded their 90% percentile in only one patient at this time. Concerning fibrinolysis markers PAP and XIFDP the majority of patients showed elevations higher than their 90% baseline percentile only 1 h postoperation. Correlation analysis revealed significant dependencies between TAT levels during and at the end of CPB and PAP levels 1 h postoperation (R = 0.55 and R = 0.56 respectively). Furthermore, 1 h postoperation XIFDP levels were significantly correlated with both TAT and PAP. Peak XIFDP levels at the same time correlated with blood loss via thoracic drains (R = 0.56). Thus, we suggest that hyperfibrinolysis in patients undergoing CPB is at least partly due to hypercoagulation. Clinically, this may implicate that intensified anticoagulation could prevent hyperfibrinolysis and reduce postoperative blood loss.