Calculation of the amount of blood to transfuse based on the hematocrit of packed RBCs and the desired increase in hemoglobin level
Calculation of the amount of blood to transfuse based on the hematocrit of packed RBCs and the desired increase in hemoglobin level
Desired increase in hemoglobin
Hematocrit of donor red cells
50%
60%
75%
80%
2 g/dL
12 mL/kg
10 mL/kg
8 mL/kg
7.5 mL/kg
3 g/dL
18 mL/kg
15 mL/kg
12 mL/kg
11.2 mL/kg
4 g/dL
24 mL/kg
20 mL/kg
16 mL/kg
15 mL/kg
The amount of blood (volume or number of units) depends on the starting hemoglobin level, desired increase, hematocrit of the packed RBCs, and size of the patient, and requires some empirical dose-finding for each individual. Units with CPD-A tend to have hematocrits close to 75%; units with additive solutions tend to have lower hematocrits. As an example calculation, to raise hemoglobin level by 4 g/dL in a patient weighing 40 kg and receiving blood with the AS1 additive (with a hematocrit of 60%) would require 800 mL. This calculation assumes a blood volume of 70 mL/kg body weight. In many cases, it may be easier to order a certain number of units rather than a volume of blood, especially for adults.
