Decide the minimum acceptable level to target therapy for. This usually is either the minimum level of the coagulation factor to maintain normal hemostasis or, if the patient has suffered trauma or needs major surgery, the minimum level needed to prevent excessive bleeding.
ideal number of factor units to give =
= ((increment wanted) * (plasma volume))
where:
• increment wanted =
= (fractional change in activity between post- and pre-transfusional specimens) = (((percentage of activity after transfusion) - (percentage of activity before)) / 100)
• Fibrinogen is measured in mg/dL, not in units of activity per mL. In fibrinogen replacement calculations, the plasma volume needs to be converted to deciliters for dosage calculations.
actual number of factor units to give =
= ((ideal number of factor units to give) / (fractional yield you "expect"))
where:
• fractional yield is the in vivo recovery
• For prothrombin complex, the fractional yield expected is 50%.
number of product units to give =
= ((actual number of factor units to give) / (number of factor units per product unit))
volume of product units given =
= (number of product units to give) * (volume per product unit)
