Our pediatric blood transfusion volume calculator uses a formula for blood transfusion volume described in an article titled Calculating the required transfusion volume in children written by Drs. Davies P, Robertson S, Hegde S, Greenwood R, Massey E, and Davis P from the Paediatric Intensive Care Unit, Bristol Royal Hospital for Children. This calculator estimates the volume of blood transfusion for children required to achieve the aimed hemoglobin increment.

Why do I need a blood transfusion calculator?

Estimating the blood transfusion volume for adult patients is very simple. One unit of packed red blood cells usually raises the hemoglobin concentration by 1 g/dl or hematocrit by 3%. This transfusion practice is imprecise, but it's widely recognized and applied.

For children, though, it's understandable that a calculation is needed. Depending on their weight and age, their total blood volume can vary substantially. The pediatric transfusion volume of blood required for the hemoglobin increment of 1 g/dL administered to an infant is considerably lower than that needed for an adolescent.

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Which values do I need to estimate the blood transfusion volume for children?

The values required to calculate the blood volume for transfusion are:

  • the patient's weight in kilograms;
  • hematocrit in %;
  • the desired increment in hemoglobin in g/dL.

Hematocrit is the percentage of volume of red blood cells in blood, with normal value ranges 42-65% for neonates in the first month, 33-55% in the second month, 28-41% from third to sixth month, and 31-41% after the sixth month of life. For children between 1 and 5 years of age, the norm is 31-44%, and after the fifth birthday it's roughly 37-48% for males and 34-44% for females.

The increment in hemoglobin is the difference between the patient's hemoglobin and the aimed level. Transfusion is usually used to maintain a blood hemoglobin concentration above 10 g/dL.

What's the formula for blood transfusion volume?

The formula for pediatric blood transfusion volume (BTV) developed by Drs. Davies P, Robertson S, Hegde S, Greenwood R, Massey E, and Davis P and described in the article Calculating the required transfusion volume in children is as follows:

BTV = weight (kg) * aimed increment in hemoglobin (g/dL) * 3 / hematocrit

Małgorzata Koperska, MD

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Pediatric Blood Transfusion Volume Formula