Age of transfused red cells and early outcomes after cardiac surgery

Background. Red blood cells (RBC) undergo many changes during storage. Such changes are associated with reduced oxygen-carrying capacity and transfusion-related inflammatory reactions. The clinical significance of these changes in the cardiac surgical setting is unclear. This observational cohort study investigates the association between age of transfused RBC and early outcomes after cardiac surgery. Methods. The cardiac surgery database at St. Vincent's Hospital Melbourne was cross-referenced with the Blood Transfusion Services database. In all, 670 consecutive patients who had nonemergency coronary artery bypass grafting or aortic valve replacement, or both, between June 2001 and June 2007 and had at least 2 RBC units transfused were studied. The storage variables studied were mean age of RBC, age of oldest RBC unit transfused, and transfusion of RBC stored longer than 30 days. Age of transfused blood was analyzed using logistic and linear regression analysis to determine an independent association with clinical outcomes: postoperative early mortality, renal failure, pneumonia, intensive care unit stay, and ventilation hours. Patient preoperative risk profile (EuroSCORE) and total number of RBC units transfused were adjusted for. Results. The storage age of RBC was not independently associated with any of the endpoints studied. The total quantity of RBC transfused was significantly associated with all studied endpoints. Conclusions. Under current transfusion practice, the age of transfused RBC is not associated with early mortality and morbidity after cardiac surgery.