SIMPLE, ACCURATE EQUATIONS FOR HUMAN-BLOOD O2 DISSOCIATION COMPUTATIONS

Hill's equation can be slightly modified to fit the standard human blood O2 dissociation curve to within ± 0.0055 fractional saturation (S) from O < S < 1. Other modifications of Hill's equation may be used to compute PO2 (Torr) from S (Eq. 2), and the temperature coefficient of PO2 (Eq. 3). Variations of the Bohr coefficient with PO2 are given by Eq. 4. 1) S = (((PO23 + 150 PO2)-1 X 23,400) + 1)-1. 2) 1n PO2 = 0.385 1n (S-1-1)-1 + 3.32 - (72 S)-1 - 0.17(S6). 3) Δ1n PO2/ΔT = 0.058((0.243 X PO2/100)(3.88) + 1)-1 + 0.013. 4) Δ1n PO2/ΔpH = (PO2/26.6)(0.184) - 2.2. Procedures are described to determine PO2 and S of blood iteratively after extraction or addition of a defined amount of O2, and to compute P50 of blood from a single sample after measuring PO2, pH, and S.