Washing of blood may be used to remove plasma proteins, electrolytes and cell debris from packed RBCs. Washing of RBCs reduces RBC recovery and is associated with the risk of contamination. The impact of transfusion of older RBC units on morbidity and mortality is still a matter of debate. Solid data on patients’ outcomes using older blood are still lacking.

In the present randomized controlled blinded trial, beagles were transfused with either 7- or 42-day-old washed or unwashed blood. Twelve to 26% of the RBCs were lost during the washing process. Washing of older RBCs resulted in improved survival rates, shock score, lung injury, cardiac performance and liver function. In contrast, washing fresh RBCs worsened all these clinical parameters.

The conclusion of this canine transfusion study was that fresh RBCs should not be washed routinely to avoid poor clinical outcome. Findings of this canine model should be verified in human transfusion practice.

– Rainer Moog