The effect of leukoreduction and prolonged storage on coagulation in cold-stored whole blood: An in vitro study.

Background and objectives: Cold-stored whole blood (CSWB) for haemodynamically unstable bleeding patients is especially convenient when platelets are otherwise unavailable and simple logistics are favoured, as in prehospital situations. Storage times exceeding the currently common 21 days would be beneficial in situations where normal blood processing and distribution is disturbed. To better understand extended-storage CSWB haemostatic properties, we studied leukoreduced CSWB (LR-CSWB) and non-leukoreduced CSWB (non-LR-CSWB) for 5 weeks of cold storage.

Materials and methods: Non-LR-CSWB was donated by seven donors and refrigerated for 5 weeks. Eight units of 20-day-old LR-CSWB returned from clinical rotation unused were stored for an additional 2 weeks. Previously published results were used for early-storage LR-CSWB data. Blood counts, coagulation assays, multiple electrode aggregometry, thrombin generation, rotational thromboelastometry and sonorheometry were analysed.

Results: Regardless of leukoreduction, markedly reduced platelet aggregation and increasing FXIII levels as a sign of platelet activation were seen during storage. Coagulation factors generally decreased and clotting times increased during storage, but endogenous thrombin potential remained normal at 5 weeks in both groups. Viscoelastic assays displayed conflicting results later during storage, with extremely low clot stiffness in sonorheometry concomitantly with apparently adequate clotting in thromboelastometry.

Conclusion: Most haemostatic changes in LR-CSWB and non-LR-CSWB occur within the first 2 weeks of storage. Little difference remains between LR-CSWB and non-LR-CSWB aged 5 weeks. Differences in viscoelastic properties suggest that clot strength may be weaker than thought already in 14-day-old CSWB regardless of leukoreduction.