Platelet quality after washing: the effect of storage time before washing

BACKGROUND: Patients who have experienced anaphylactic transfusion reactions receive washed platelet (PLT) concentrates (PCs) where the plasma has been substituted with a PLT additive solution. This study compares the in vitro quality of PCs washed at the beginning of the storage period (Day 1) to PCs washed at the end of storage (Day 7). STUDY DESIGN AND METHODS: PLTs were prepared by the buffy coat procedure. Two concentrates were pooled and then split to obtain an identical pair of PCs. One of the PCs was washed with T-Sol on Day 1 and the other on Day 7 of storage. Swirling, blood gases, and metabolic variables were analyzed before washing. Analyses of surface expression of CD62P and coagulation by free oscillation rheometry (FOR) were performed before and after washing. RESULTS: pH was acceptable in all PCs. Washing on Days 1 and 7 increased the CD62P surface expression. The FOR variables clotting time and clot retraction were not influenced by washing on either day. Washing resulted in a decrease in the number of PLTs and the decrease was larger on Day 7 compared to Day 1. CONCLUSIONS: PLTs washed on Days 1 and 7 of storage are effected by washing in a similar manner. However, a larger loss of PLTs occurred during washing on Day 7.