Background: In patients who have large bleeds, there is a tendency to transfuse more plasma and platelets than recommended in earlier guidelines, and accordingly many hospitals now provide "transfusion packages" with an intended red cell:platelet:plasma ratio of 1:1:1. The purpose of this study was to investigate in vitro functions of transfusion packs compared with fresh whole blood.
Material and methods: "Reconstituted whole blood" was prepared with the same ratio of red cells, platelets and plasma as used in local transfusion packages. The aggregation and thrombin-antithrombin complex formation responses to collagen stimulation of this reconstituted whole blood were compared with those of fresh whole blood. The storage time of red cells and platelets was varied in a systematic manner, giving nine different compositions of reconstituted whole blood that simulated transfusion packs.
Results: The responses varied significantly between whole blood and reconstituted whole blood -and between the reconstituted whole blood of different compositions. A significant decrease (p<0.005) in collagen-induced platelet count reduction was seen with increasing platelet and red blood cell age. Thrombin-antithrombin complex formation peaked in studies with platelets stored for 5 days. The red cells stored for the longest time induced the greatest thrombin-antithrombin complex formation. Fresh whole blood gives more consistent responses, and the aggregation response to collagen is stronger than in reconstituted whole blood.
Discussion: Our results indicate that in vitro responses of reconstituted whole blood vary substantially according to how long the red cells and platelets are stored for. As the responses obtained by testing whole blood are more consistent and usually stronger, the alternative use fresh whole blood in special conditions should not be excluded without further consideration.