Effect of prophylactic transfusion of stored RBCs on oxygen reserve in response to acute isovolemic hemorrhage in a rodent model

related decline in 2,3 DPG that may reduce the ability to unload oxygen (O-2) to tissue. The objective of this study was to compare the effect that transfusion of stored 2,3 DPG-depleted rat blood (7 days in CPDA-1) had on the O-2 reserve in conscious rats, with that of the transfusion of fresh blood (<2-hour storage). STUDY DESIGN AND METHODS: Anemic rats (Hb, 80 g/L) received either fresh packed RBCs or stored RBCs to raise Hb levels to 140 g per L. They then underwent isovolemic hemorrhage mimicking surgical blood loss to the point of O-2 supply dependency (OSD). Critical O-2 delivery (DO(2)crit), Hb concentration, and O-2 extraction at OSD were measured in a metabolic chamber. RESULTS: After transfusion, RBC DPG decreased by 50 percent in the stored-blood group, and the p50 value decreased by 5 mmHg (32.1 +/- 2.5 mmHg vs. 37.5 +/- 3.0). DO(2)crit was similar in the two groups (fresh blood: 2.79 +/- 0.44 mL/min x g(-1); stored blood, 2.99 +/- 0.76 mL/min x g(-1)). The critical Hb concentration at DO(2)crit was higher in the stored-blood group (44 +/- 4 g/L) than in the fresh-blood group (38 +/- 5 g/L); the cardiac index and O-2 extraction ratio in the two groups were not different. Under conditions of severe normovolemic anemia in rats, depletion of DPG and a decrease in p50 had only minor effects on the O-2 reserve. At OSD, under these conditions, O-2 consumption is not limited by diffusion. CONCLUSION: The physiologic impact of DPG depletion in transfused stored blood on oxygen availability in normal rats appears to be small and may be clinically inconsequential.