Influence of circulating levels of fibrinogen and perioperative coagulation parameters on predicting postoperative blood loss in cardiac surgery: a prospective observational study.

ABSTRACT

BACKGROUND: Fibrinogen, the major clotting protein in blood plasma, plays key roles in blood coagulation and thrombosis. In this prospective cohort study, we measured patient's fibrinogen levels and common coagulation parameters before and after cardiopulmonary bypass (CPB) and examined their relationships with postoperative blood loss. STUDY DESIGN: Patients undergoing cardiac surgery with CPB who did not have pre-existing coagulopathy were eligible. Standard blood and coagulation testing were performed before and after CPB. The association of these variables with postoperative blood loss (estimated blood loss from CPB) was assessed with Spearman's ranked correlation and multivariable linear regression models. RESULTS: Two hundred and fifty patients were enrolled in the study. The median blood loss was 780 mL (range 320-2340 mL). Variables independently associated with increasing blood loss were lower post-CPB platelet counts (p<0.001), lower postoperative fibrinogen levels (p<0.001), and larger percent decrease in fibrinogen levels (p<0.05). There was no correlation between preoperative fibrinogen levels and preoperative coagulation tests with postoperative bleeding. The only significant independent predictors of transfusion in a logistic regression model were postoperative fibrinogen concentration. CONCLUSION: Postoperative fibrinogen, the larger percent decrease in fibrinogen, and postoperative platelet levels are markers of bleeding and blood transfusion requirements after CPB than preoperative standard screening tests. Postoperative fibrinogen had the best predictive value of all tests of postoperative blood loss.