Does Hyperfibrinolytic Activity Occur During Cardiopulmonary Bypass from Blood Exposed to Pleural Surfaces?

During cardiac surgery with cardiopulmonary bypass (CPB), fibrinolytic activity may be stimulated when blood exposed to pleural surfaces is suctioned into the extracorporeal circuit (ECC). The purpose of this study was to determine the effect of reinfused blood exposed to pleural surfaces on systemic fibrinolytic activity. Following Institutional Animal Care Utilization Committee approval, 120 ml of blood was drawn from the femoral artery of 4 pigs and placed in both pleural cavities, where it remained for 120 min during CPB. After this time, the exposed blood was suctioned back into the ECC. Blood samples were drawn at the following times: 40 min prior to median sternotomy, 30 and 90 min during CPB, and 30 min post-suction. Tests performed on the samples included thromboelastography (TEG), D-dimer (DD), fibrin degradation products (FDP), fibrinogen concentration, activated clotting time (ACT), hematocrit, and platelet count. TEG index decreased significantly in the circuit following suction (5.28 ± 0.45 vs. 0.98 ± 1.86, p < 0.0007), while fibrinolytic activity increased (6.25 ± 1.50%) in the ECC when compared to pleural blood (2.17 ± 1.04%, p < 0.01). The DD and FDP were both elevated in the systemic circulation following suction of the pleural blood, although statistical significance was not achieved. The ACT was significantly elevated in the pleural fluid during CPB (707 ± 213) compared with the ECC (378 ± 32, p < .003), which may indicate an accelerated consumption of coagulation factors. In conclusion, blood exposed to pleural surfaces may have increased fibrinolytic activity, but systemic hyperfibrinolysis was not seen.