The storage lesion of packed red blood cells affects coagulation

The storage lesion of packed red blood cells (PRBCs) consists of biochemical changes associated with increased inflammatory mediators and decreased oxygen-carrying capacity. The effect of storage on the coagulation system is less well studied. The purpose of this study is to determine how PRBC storage time affects the activated coagulation time (ACT), using an in vitro model.

Type-matched PRBCs and fresh-frozen plasma were mixed, warmed to 37°C, and recalcified. The microsample ACT was repeatedly determined by 2 methods (ACT+ and ACT-LR) at 1 week, 3 weeks, and 5 weeks after date of donation. Hematocrit, pH, and ionized calcium were measured to assess how the model compared to physiologic circumstances. Statistical analysis was performed using the Student 2-tailed t-test with unequal variance.

Hematocrit, pH, and ionized calcium were successfully maintained within narrow ranges. The model was notably acidotic, consistent with circumstances of shock and massive transfusion. There was no significant difference in the ACT+ between week 1 and week 3 (P = .183), but there was a significant difference between week 3 and week 5 (P = .029) and between week 1 and week 5 (P = .007). The ACT-LR showed a significant difference between week 1 and week 3 (P = .001), but not between week 3 and week 5 (P = .286). There was again a strong difference between week 1 and week 5 results (P = .011).

In an isolated in vitro model, the storage lesion of PRBCs is associated with decreased coagulation. This may have relevance for transfusion practices in coagulation-sensitive circumstances such as trauma.