Transfusion Volume
Red blood cell volume needed to raise hemoglobin to a target in children.
Method
Volume (mL) = weight (kg) × hemoglobin increase (g/dL) × 3 ÷ unit hematocrit
Derived from 379 transfusions in pediatric intensive care, where the measured rise was about 5 mL/kg per 1 g/dL of hemoglobin with red cells at a hematocrit of 0.6. At that hematocrit, 10 mL/kg raises hemoglobin by about 2 g/dL. The traditional factor of 3 or 4, without the hematocrit term, gives smaller volumes than this measured relationship.
The estimate assumes no ongoing bleeding. During cranial vault surgery, losses continue, so replacement is guided by measured hemoglobin and hemodynamics. Follow your institution's transfusion protocol.
Source: Davies P, Robertson S, Hegde S, Greenwood R, Massey E, Davis P. Calculating the required transfusion volume in children. Transfusion. 2007;47(2):212–216. PubMed 17302766.