Influence of erythrocyte concentrate storage time on postsurgical morbidity in cardiac surgery patients

Background: The transfusion of erythrocytes that have been stored for long periods of time can produce visceral ischemia and favor the acquisition of postsurgical infections. To estimate the role of the duration of storage of erythrocytes on morbidity in cardiac surgery, we performed an observational study. Methods. All patients (n = 897) undergoing cardiac surgery during three consecutive years were included. Morbidity (main outcome measure) was evaluated by means of four surrogate measures: duration of stay in the intensive care unit longer than 4 days, mechanical ventilation time longer than I day, perioperative myocardial infarction rate, and severe postoperative infection rate. The mean duration of storage of all erythrocytes transfused and the duration of storage of the oldest unit transfused were used as storage variables. Results: After considering multiple confounding variables related to patient severity, illness, and surgical difficulty, the duration of storage of erythrocytes was found to be associated neither with a more prolonged stay in the intensive care unit or mechanical ventilation time nor with increased rates of perioperative infarction, mediastinitis, or sepsis. However, each day of storage of the oldest unit was associated with an increment of the risk of pneumonia of 6% (95% confidence interval, 1-11; P = 0.018). The cutoff point of maximum sensitivity and specificity (54.8 and 66.9%) associated with a greater risk for pneumonia corresponded to 28 days of storage for the oldest unit (odds ratio, 2.74; 95% confidence interval, 1.18-6-36; P = 0.019). Conclusions: Prolonged storage of erythrocytes does not increase morbidity in cardiac surgery. However, storage for longer than 28 days could be a risk factor for the acquisition of nosocomial pneumonia.