Abstract 18252: Washing of Stored Red Cells Prevents Transfusion Related Acute Lung Injury but Not Transfusion Associated Coagulopathy

Objective To determine if washing of old Red Blood Cell (RBC) units prior to transfusion will prevent transfusion mediated organ dysfunction in our large animal experimental model. Method Adult White-Landrace pigs (50-70kg, n=32) were randomized to either sham procedure or to receive an allogeneic transfusion of 1-, 14- or washed 14-day RBCs. Endpoints included characterization of the RBC storage lesion, serial functional and biochemical measures of lung and renal injury, assessment of platelet function using platelet aggregometry, platelet activation using FACS and coagulation using ROTEM. All pigs were recovered for 24 hours prior to organ harvest. Results Transfused pigs received 1000mls of cross-matched allogenic leucodepleted RBC stored in SAG-M preservative for either 1 or 14 days. Accumulation of toxic metabolites within the supernatant as well as cellular changes showed considerable homology to those measured in SAG-M stored human RBC units. Transfusion of allogeneic porcine RBCs was associated with 24hr RBC survivals of greater than 75% and sustained increases in haematocrit irrespective of age of unit. Despite enhancing oxygen delivery, transfusion of 14-day old RBCs decreased tissue oxygen unloading, caused significant hypoxia and pulmonary hypertension. This was associated with plasma platelet depletion with sequestration into lung parenchyma, platelet dysfunction with decreased aggregation in response to ADP stimulation, coagulopathy and inflammation with increased P-selectin expression in circulating platelets. Washing of aged RBC units prior to transfusion ameliorated TRALI and inflammation, but had no effect on transfusion induced coagulopathy and platelet dysfunction. Data are summarised below. Conclusion Washing of aged RBC units prevents TRALI and should be evaluated in a randomized controlled in patients undergoing cardiac surgery. RBC transfusion mediated coagulopathy is a novel finding which is not affected by washing.