Venesection in cyanotic heart disease – calculation of volume to be removed
Venesection in cyanotic heart disease is done only in symptomatic polycythemia with hemoglobin > 20 gm% and hematocrit > 65 %. Blood removed has to be replaced with equal amount of saline to avoid hypovolemia and reduce the hematocrit.
Volume of blood to be removed by venesection in ml:
[(Observed PCV – Desired PCV ) / Observed PCV] x 70 x body weight in Kg.
Desired PCV (packed cell volume or hematocrit) is calculated based on the oxygen saturation. Average desired PCV is about 60 for a person with cyanotic congenital heart disease (CCHD).