The normal value of P50 on the oxyhaemoglobin dissociation curve in an adult is:

C i.e., 3.6 K Pa P50 is the P02 at which hemoglobin is half P50 is the index of affinity of hemoglobin for 02. Higher the P50, the lower the affinity of hemoglobin for 02. Under normal condition when: - Hb is normal - PaCO2 is 110 mm Hg - Temperature is 37degC - 2,3 DPG is 15 jtmol/gm of Hb. The value of P50 is 25 mm Hg - 3.6 KPaQ. (1 mm Hg = 0.14 KPa)