R. Chae1, A. Price1, M. R. Baucom1, C. Nguyen1, R. Schuster1, A. B. Lentsch1, C. C. Caldwell1, M. Goodman1, T. A. Pritts1 1University Of Cincinnati, Surgery, Cincinnati, OH, USA
Introduction: The red blood cell (RBC) storage lesion collectively describes the morphological, biochemical, and functional changes to red blood cells that occur when stored ex vivo. It has been well described in murine and human blood but has not been studied in swine. Porcine models of polytrauma and hemorrhage have become increasingly utilized to study physiologic responses that are more similar to humans than murine models. Thus, study of the RBC storage lesion in porcine stored blood is warranted to better define the effects of varied resuscitation strategies in large animal models of hemorrhage. We hypothesized that the RBCs in porcine packed RBCs (pRBCs) would undergo an RBC storage lesion that would increase in severity over the time of storage, similar to that previously reported in murine and human blood.
Methods: Whole blood was collected via central venous access on seven female Yorkshire pigs and stored in citrate phosphate double dextrose. The whole blood was then centrifuged and the plasma supernatant aspirated. Additive storage solution (AS-3) was added to the RBC pellet to create pRBCs. The pRBCs were stored at 4°C for 42 days, the current FDA limit for human pRBCs, and tested on day of collection and then weekly for markers of the RBC storage lesion, including RBC counts, biochemical measurements, phosphatidylserine expression, and free hemoglobin.
Results: Throughout the duration of storage, RBC concentration and hemoglobin values remained stable. RBC volume increased over time (58.8 mm3 on day 0 vs. 71.1 mm3 on day 42, p<0.01) with resultant increases in hematocrit. The mean pH decreased (6.9 day 0 vs. 6.5 day 42, p<0.01) and extracellular potassium quickly increased to beyond the test upper range limit by day 7 (>9 mEq/L). Lactate levels increased significantly over the storage duration (0.9 mEq/L day 0 vs. 9.4 mEq/L day 42, p<0.01). Phosphatidylserine expression as determined via flow cytometry with Annexin V binding remained constant (4.6% day 0 vs. 5.4% day 42, p=0.99). Cell-free hemoglobin increased progressively during storage and was significantly elevated by day 42 (18.1 mg/dL day 0 vs. 2337 mg/dL day 42, p=0.02; FIGURE 1).
Conclusion: Porcine pRBCs stored in AS-3 demonstrate a progressive RBC storage lesion over 42 days of storage as seen with increasing acidity, potassium and lactate levels, RBC volumes, and extracellular hemoglobin. These findings are similar to aspects of the human and murine pRBC storage lesion. However, porcine RBCs demonstrated stable low levels of phosphatidylserine expression, which is distinct from human and mouse stored blood studies. Direct comparison to human pRBCs is warranted as well as study of porcine RBC aggregability in the setting of low phosphatidylserine expression on the cell membranes.
