Factors associated with excessive bleeding in cardiopulmonary bypass patients

Background

Excessive postoperative bleeding (>1 l/24 hours) and transfusion requirements for major cardiac surgical interventions vary widely. Factors such as preoperative status and medication, cardiopulmonary bypass (CPB), activation of coagulation, fibrinolysis and complement all play a determinant role in postoperative bleeding.

Objective

To determine the incidence and host factors associated with EB in CPB patients without antifibrinolytic prophylaxis.

Patients and methods

We performed a cross-sectional study of 26 patients (15 men; mean age 64.5 years, SD 1.4), from a clinical trial of 50 CPB patients, who did not receive antifibrinolytic prophylaxis. Surgery performed was: 12 CABG, 10 valvular replacement and four patients underwent both procedures. Variables were collected preoperatively, at ICU admission, and at 4 and 24 hours after surgery. The associations of excessive bleeding with demographic, clinical and genetic factors were analyzed. We used SPSS-12.2 software for statistical purposes.

Results

The incidence of excessive bleeding (EB) was 50%. BMI <26.4 (25–28) was associated with EB (P = 0.026). Preoperative levels of leptins (P = 0.059) and PAI-1 (P = 0.014) were predictors for EB. Body temperature <30.7 (30–32)°C during CPB (P = 0.037) and at ICU admission (P = 0.029) was associated with EB. We found greater activation at admission of C1q (P = 0.019), C1-inhibitor (P = 0.029) and B factor (P = 0.005), C7 (P = 0.005), with lower levels of PAI-1 (P < 0.001), prothrombin time (PT) (P = 0.039), leptins (P = 0.014) and leptin/BMI (P = 0.019) in those patients with EB. In the same patients at 4 hours, we found lower levels of C1q (P = 0.004), C1-inhibitor (P = 0.046), C3 (P = 0.010), B factor (P = 0.016), C7 (P = 0.004), PT (P = 0.034), leptins (P = 0.004) and leptin/BMI (P = 0.011). In addition lower levels at 24 hours of C1q (P = 0.039), leptins (P = 0.005) and leptin/BMI (P = 0.003) were found in patients with EB. These patients showed a hyperdynamic state and greater transfusion requirements.

We observed a statistically significant positive correlation between the complement system (alternative and final pathway: C3, B factor and C7) and the following variables: sTNF, PAI, PT and leptins; and an inverse correlation with bleeding.

Conclusion

The incidence of excessive bleeding was 50%; coagulation, fibrinolysis, complement and inflammation parameters were involved. Our results suggest that patients admitted with low BMI, PAI and leptins together with higher activation of the complement system had greater transfusion requirements over 24 hours.