Randomized controlled trial of 7, 28, vs 42 day stored red blood cell transfusion on oxygen delivery (VO₂ max) and exercise duration

Background: Few studies have rigorously assessed the impact of red blood cell (RBC) transfusion on oxygen delivery. Several large trials demonstrated no clinical outcome differences between transfusion of shorter-storage vs prolonged-storage RBCs. These trials did not directly assess functional measures of oxygen delivery. Therefore, it is not clear if 42-day stored RBCs deliver oxygen as effectively as 7-day stored RBCs. Study Design and Methods: Leukocyte-reduced RBCs were collected by apheresis in AS-3. Thirty subjects were randomized (1:1:1) to receive 2 units of autologous RBCs at either 7, 28, or 42 days following donation. VO₂ max testing, using a standardized protocol to exhaustion, was performed 2 days before (Monday) and 2 days after (Friday) the transfusion visit (Wednesday). The primary endpoint was the percent increase in VO₂ max between Monday and Friday. The secondary endpoint was the percent change in duration of exercise for the same time points. Results: Hemoglobin levels decreased by 2.8 ± 1.4 g/dL after donation and increased by 2.1 ± 0.6 g/dL after transfusion. This change in hemoglobin was associated with expected decreases (then increases after transfusion) in VO₂ max and exercise duration. No differences were observed between 7-day and 42-day RBC transfusion for percent increase in median [IQR] VO₂ max (10.5 [0.2-17.3] vs 10.9 [5.7-16.8], P =.41) or for percent increase in exercise duration (5.4 [4.1-6.9] vs 4.9 [2.0-7.2], P =.91), respectively. Results were similar for 28-day RBCs and were consistent across the ITT and per-protocol analysis populations. Conclusion: These data indicate that 42-day, 28-day, and 7-day RBCs have similar ability to deliver oxygen.