Improved maintenance of 2,3 DPG and ATP in RBCs stored in a modified additive solution

BACKGROUND: All currently used systems for the storage of RBCs result in loss of 2,3 DPG and an associated increase in affinity for oxygen. Previously, it was demonstrated that a hypotonic additive solution for RBC storage (Erythro-Sol)(4.5) resulted in prolonged maintenance of 2,3 DPG when blood was collected in 0.5 CPD (half-strength CPD), but not when full-strength CPD was used. The present study aims at improving the quality of stored RBCs collected in ordinary CPD. STUDY DESIGN AND METHODS: A new formulation of Erythro-Sol (Erythro-Sol 2) (pH 8.8) in a larger volume (150 mL) was compared with Erythro-Sol (ErythroSol 1). In vitro measures during 49 days of storage in the two additives were compared using WBC-depleted RBCs after whole-blood collection in CPD and separation in an automated blood separation instrument (Opti-press 11, Baxter Healthcare). RESULTS: The maintenance of RBC ATP and 2,3 DPG was significantly better in Erythro-Sol 2 than in ErythroSol 1. The ATP concentration rose to approximately 30 percent above initial level in both systems; however, the maximum occurred on Day 21 in Erythro-Sol 2 as compared with Day 14 in Erythro-Sol 1. In RBCs stored in Erythro-Sol 2, the mean RBC 2,3 DPG concentration increased to 14 percent above initial level on Day 7, then decreased to the initial level on Day 14, whereas in Erythro-Sol 1, the 2,3 DPG had decreased to 85 and 50 percent on Days 7 and 14, respectively. Both intracellular pH and extracellular pH were slightly higher in Erythro-Sol 2 than in Erythro-Sol 1 units but decreased rapidly during the first storage week, which seems to have been the major reason for the limitation in the time of maintenance of 2,3 DPG. Hemolysis was very low in both systems, 0.14 to 0.17 percent on Day 49. The additional amount of inorganic phosphate submitted with Erythro-Sol 2 did not raise concern because the phosphate content in the storage medium, being 1.3 +/- 0.2 mmoL on Day 0, decreased to values below 1 mmoL during most of subsequent storage. CONCLUSION: Erythro-Sol 2 is an improved additive solution for the storage of RBCs.