Posttransfusion recovery of stored red blood cells in very low birth weight infants using a hemoglobin balance model

BACKGROUND:  A Hb balance model was used in very low birth weight (VLBW) infants to predict posttransfusion Hb levels from which we inferred allogeneic RBC recovery after transfusion of RBCs stored for varying periods of time. STUDY DESIGN AND METHODS:  Premature VLBW infants receiving RBC transfusions during the 1st month of life were evaluated retrospectively for RBC survival of stored donor blood. Actual Hb levels measured in infant blood 1 and 2 days after RBC transfusions were com-pared to those predicted using a Hb balance model based on factors affecting blood Hb loss and gain. Transfusions were subgrouped according to whether or not infants were clinically stable at the time of RBC transfusion. Model-predicted RBC recovery was also evaluated relative to duration of RBC storage. RESULTS:  Model-predicted mean (± SD) Hb levels 2 days after transfusion among the 30 VLBW infants receiv-ing a total of 57 RBC transfusions were only 4 percent higher than actual values observed (15.2 ± 1.2 g/dL vs. 14.7 ± 1.4, respectively; p < 0.05). The infant's clinical status at the time of transfusion did not affect predicted 1- and 2-day posttransfusion RBC recovery. Model-predicted recovery of transfused RBCs was modestly, but significantly, decreased with increasing duration of donor RBC storage (i.e., 10% lower by 42 days—the maximal allowed storage period for donor blood [p < 0.01]). CONCLUSIONS:  Our model-predicted RBC survival results are consistent with—but not direct evidence of—hemolysis of donor blood after RBC transfusion. Although observed post-RBC Hb levels 2 days after transfusion averaged only 4 percent less than predicted, model-predicted survival of donor RBCs at 42 days suggested a modest decrease (i.e., by 10%).