Plasmin generation and D-dimer formation during cardiopulmonary bypass

The purpose of this study was to estimate the in vivo rates of plasmin and D-dimer generation for comparison with the rate of fibrin formation during cardiopulmonary bypass (CPB), a procedure known to induce a hyperfibrinolytic state. Plasmin and D-dimer generation rates were based on measured levels of antiplasmin, plasmin-antiplasmin complex and D-dimer obtained before, during and after CPB from nine males, combined with a computer model of each patient's vascular system that continuously accounted for secretion, clearance, hemodilution, blood loss and transfusion. At baseline the average plasmin and D-dimer generation rates were 0.27 ± 0.07 and 0.18 ± 0.07 pmol/s, respectively. Within 5 min of CPB initiation, plasmin generation increased over 100-fold to 36 ± 40 pmol/s while D-dimer generation increased 200-fold to 37 ± 39 pmol/s. For the remainder of the CPB, average plasmin and D-dimer generation remained 20-fold to 30-fold above baseline levels. During CPB, the rate of D-dimer generation was similar to the rate of total fibrin formation, indicating that, in the absence of fibrinolytic inhibitors, CPB induces plasmin-mediated removal of fibrin from the vascular system at a rate similar to the rate of fibrin formation.