Parameters:
(1) intended increment in hemoglobin in g/dL
(2) hematocrit of blood product as a decimal fraction
(3) body weight of the child in kilograms
intended increment in hemoglobin =
= (desired hemoglobin) - (current hemoglobin)
blood volume to transfuse in mL =
= (body weight in kilograms) * (target increment in hemoglobin) * 3 / (hematocrit of the blood product)
where:
• The simple relation between hemoglobin and hematocrit is: hemoglobin = (hematocrit in percent) / 3.
• A portion of the expression appears to be calculating the hemoglobin content of the blood product. Body weight is often used in children to estimate the blood volume.
• The hematocrit for blood products reported by the authors for England is 0.6 (range 0.55 to 0.65). US blood products may have a hematocrit that is slightly higher (0.7 to 0.8).
• Postoperative monitoring can be done at 1 hour after the transfusion is completed. Hemoglobin levels after replacement are stable unless there is bleeding or hemolysis.
Children were excluded from the study if they had a condition that might confound the analysis due to increased red blood loss and/or hemodilution:
(1) active bleeding or blood loss from drains
(2) active hemolysis
(3) infusion of crystalloid or colloid
(4) dialysis or ECMO
