Adverse Events and Risk Factors of Blood Transfusion in Cardiovascular Surgery: A Prospective Cohort Study

Background: Hemodilution, transoperative bleeding and cardiopulmonary bypass (CPB) are some of the factors associated with high transfusion rates in cardiac surgery. Objective: To analyze the incidence of blood transfusion and early postoperative outcomes in cardiac surgery patients. Methods: Cohort study of patients undergoing cardiac surgery in a university hospital, consecutively enrolled from May 2015 to February 2017. Data were prospectively collected and comparisons were made between two patients’ groups: transfused and not transfused. Student's t-test, chi-square test, and logistic regression were used, and a p-value < 0.05 was considered significant. Results: Among the 271 patients evaluated, 100 (37%) required transfusion in the transoperative (32.1%) and/or postoperative periods (19.5%). The following predictors of transfusion were identified by multivariate analysis: EuroScore II (OR 1.2); chronic kidney disease (CKD) (OR 3.2); transoperative bleeding ≥ 500 mL (OR 6.7); baseline hemoglobin (Hb) ≤ 10 g/dL (OR 11.5); activated partial thromboplastin time (aPTT) (OR 1.1) and CPB duration (OR 1.03). Transfusion was associated with prolonged mechanical ventilation (≥ 24h) (2.4% vs. 23%), delirium (5.9% vs. 18%), bronchopneumonia (1.2% vs. 16%), acute renal failure (3.5% vs. 25%), acute on CKD (0.6% vs. 8%), stroke or transient ischemic attack (1.8% vs. 8%), intensive care unit stay ≥ 72 h (36% vs. 57%), longer hospital stay (8 ± 4 days vs. 16 ± 15 days), as well as increased early mortality (1.75% vs. 15%). Conclusion: EuroScore II, CKD, major transoperative bleeding, preoperative Hb and aPTT values and CPB time were independent predictors of transfusion, which was associated with a higher rate of adverse outcomes, including early mortality.