Transport of gases in pulmonary capillaries- a computation of equilibrium constants arising in the oxygen dissociation curve.

A study of the simultaneous diffusion of O2 and CO2 in the presence of haemoglobin is made by considering the intermediate compound hypothesis of Adair. Our analysis exhibits explicit dependence of the fractional saturation (of haemoglobin with O2) on pCO2. It has been emphasized that discrepancies in the various numerically computed values of equilibrium constants arising in the oxygen dissociation curve may be due to inadequacy of the methods used to solve the normal equations obtained in the process of least-square curve-fitting, which are highly non-linear in character in the present context. It has been shown, by using the method suggested by Marquardt that the values of these constants lead to a saturation function which fits very well with the one based on documented data. The analysis further shows that under normal physiological conditions, the main bulk of oxygenated haemoglobin exists in the fully saturated form as HbO8 which also seems obvious from our computed values of equilibrium constants.