Clinical effects of blood transfusion during the immediate postoperative period in cardiac surgery patients

Introduction: Blood transfusion is common in patients undergoing cardiac surgery. Aim: Our goal was to investigate the association between blood transfusions in the early postoperative period and complications during Cardiac Intensive Care Unit (CICU)stay. Methods: Retrospectively analysis in 874 patients who underwent isolated coronary artery bypass grafting, valve surgery or combined procedures. Patients were allocated to two groups according to the presence (Group A) or absence (Group B) of blood transfusion during extracorporeal circulation, surgery and CICU stay. Two hundred thirty four patients with preexisting hepatic or blood diseases, atrial fibrillation, emergent surgery or those received autologous blood transfusions were excluded prior to the study. Morbidity was defined as prolonged postoperative mechanical ventilation, mechanical ventilation>7hours, reintubation, use of non-invasive ventilation, postoperative atrial fibrillation and length of hospital stay. Statistical analysis was carried out using Chi-square, Student's t-test, Relative Risk (RR) and logistic regression with statistical significance set at p<0.05. Results: In the final analysis 640 patients were included. From these, 486 patients received blood transfusion (Group A) while 154 patients were allocated to Group B. Patients in Group A were older (67 vs 62, p<0.01) and characterized by higher Euroscore I (4.9 vs 2.91, p<0.01). Patients receiving blood transfusion differed significantly in terms of prolonged mechanical ventilation (p=0.035), mechanical ventilation >7 hours (p<0.01), need for non-invasive mechanical ventilation (p=0.025) and length of hospital stay (p<0.01). No significant difference was found regarding postoperative atrial fibrillation and reintubation rate. Multivariate logistic regression indicates blood transfusion as an independent predictive factor for hospital stay over 5 days (p=0.03) and mechanical ventilation > 7 hours (p<0.01). Conclusions: Blood transfusions seem to associate with certain complications in cardiac surgery patients.