Unsettling new evidence suggests that blood stored for more than 2 weeks might be less beneficial to recipients recovering from cardiac surgery than is fresher blood. While the study falls short of heralding a wholesale change in blood-banking practices, scientists agree that it exposes the need for a large trial to determine the optimal shelf life of stored blood. The current limit is 42 days.
Laboratory research has indicated that stored blood loses quality over time (SN: 10/27/07, p. 269). But previous studies of patients who received old or new blood proved inconclusive.
"No one expects blood to get a lot better during storage. It's not vintage port," says Harvey Klein, a hematologist who heads the Department of Transfusion Medicine at the National Institutes of Health in Bethesda, Md. It may be possible to show that blood cells get "run down" over time, he says, "but it's much more difficult to demonstrate that that's harmf