Plasma activity of individual coagulation factors, hemodilution and blood loss after cardiac surgery: a prospective observational study.

BACKGROUND Hemodilution and consumption of coagulation factors during cardiopulmonary bypass has been suggested to contribute to bleeding complications after cardiac surgery. The aim was to describe the activity of individual coagulation factors after CABG in relation to hemodilution and postoperative bleeding. MATERIALS AND METHODS Plasma concentrations of fibrinogen and plasma activity of FII, FV, FVII, FVIII, FIX, FX, FXI and FXIII adjusted for hemodilution were analysed in 57 CABG patients before, and 2h and 24h after surgery. Postoperative bleeding was registered and correlations to coagulation factor activity were calculated. RESULTS Adjusted plasma concentration of fibrinogen (-14+/-6%), and plasma activity of FII (-9+/-6%), FV (-13+/-8%), FX (-13+/-7%) and FXIII (-9+/-14%) were reduced two hours after surgery compared to baseline (all p<0.001). FVII (+3+/-12%, p=0.34) and FXI (+1+/-19%, p=0.50) were unchanged, while FVIII (+23+/-44%, p=0.006) and FIX (+23+/-17%, p<0.001) increased. Twenty-four hours after surgery fibrinogen (+45+/-27%), FVIII (+93+/-66%) and FIX (+33+/-26%) were all increased (all p<0.001), while FVII (-37+/-14%, p<0.001), FXI (-4+/-18%, p=0.02) and FXIII (-6+/-15%, p=0.004) were decreased. Median postoperative blood loss was 380 ml/12h. There were significant inverse correlations between postoperative blood loss and fibrinogen concentration 2h after surgery (r=-0.33, p=0.019) and between postoperative blood loss and pre- and postoperative FXIII activity (r=-0.34, p=0.009 and r=-0.41, p=0.003, respectively), but not between blood loss and any of the other factors. CONCLUSIONS There is a marked dissociation in plasma activity of individual coagulation factors after CABG. Plasma concentration of fibrinogen and factor XIII activity correlates inversely to postoperative blood loss after CABG.