During refrigerated storage, donated red bloods cells undergo morphological and biochemical changes that may decrease their oxygen-carrying capacity. Some observational studies have suggested that longer storage intervals are associated with worse outcomes while other studies have not shown any difference.
The results of two randomized trials should help to answer this question. The ARIPI trial of premature infants, found no difference in patient outcomes for those receiving fresh red blood cells compared to those receiving standard of care (JAMA 2012;308: 1443-51).
The Red Cell Storage Duration Study, also known as RECESS, was a randomized controlled trial conducted at 33 medical centers in the United States over four years. RECESS evaluated the effect of red blood cell storage time in cardiac surgery patients. Patients were randomized to receive either leukoreduced red blood cells stored for 10 days or less or red cells stored for 21 days or more. Primary outcome was the change in the multi-organ dysfunction score through day 7. Secondary outcomes included changes in multi-organ dysfunction score through day 28, serious adverse events and mortality at 28 days post surgery (Transfusion 2014;54 Supplement: 15A).
RECESS did not detect any differences in primary or secondary end points in patients undergoing compleicated cardiac surgery who were transfused with fresh or older red blood cells. More studies are needed to settle this question in other patient populations.