Whole blood storage time impairs clot strength with minimal change in functional fibrinogen concentration

Whole blood (WB) is a preferred resuscitation strategy, yet how storage affects hemostasis remains unclear. Prior studies have shown decreased fibrinogen function during storage; however, these were limited by incomplete removal of platelet contributions. Additionally, leukoreduced (LR) versus non-leukoreduced (NLR) status in preserving fibrinogen remains unknown.

WB units (n = 15, 7 NLR, 8 nLR) were evaluated at serial time points through day 35. ROTEM EXTEM was performed. Platelet-poor plasma (PPP) from WB at day 0, day 21, and day 35 underwent western blot for fibrinogen. Functional fibrinogen was measured using the Clauss assay after freeze-thaw cycles of WB PPP to minimize platelet contribution.

As WB aged, there was a progressive decrease in alpha angle and maximum clot firmness. Platelet count dropped sharply by day 7. Western blot demonstrated no evidence of fibrinogen degradation in either LR or NLR WB. Clauss fibrinogen concentrations were unchanged from day 0 to day 35, with a modest non-significant decline by day 35 driven primarily by NLR units.

Fibrinogen did not undergo detectable proteolysis during storage of WB and had preserved function through day 35 after freeze-thaw cycles to minimize platelet contributions. NLR appeared to impact fibrinogen function with medians below 200 for day 21 and 35 but was not statistically significant. This suggests that previously reported reductions in fibrinogen function may be based on leukoreduction status, but that early changes in fibrinolysis sensitivity are more likely due to residual platelet contributions to the assays rather than loss of fibrinogen function itself.