Individual modeling of oxygen capture by the human lungs

It has been proposed that oxygen capture by the human lungs depends on four determinants: ventilation, cardiac output, oxygen partial pressure in the inspired air and the venous blood. Indeed, the theoretical-numerical model proposed recently by Kang et al. was able to interpret the known empirical relation between the average of the determinants and the average oxygen capture called VO₂. This method is tested here at the individual level in a group of 31 subjects submitted to standard pulmonary function testing and cardiopulmonary exercise testing. For this, an inverse method is used in which individual cardiac output is predicted from the clinical test data. Comparison to the cardiac output deduced from Fick principle confirms that the dynamic model is a "microscopic" justification of the "macroscopic" Fick principle. It shows that in addition to the four determinants, two secondary determinants, namely hemoglobin concentration and Bohr effect, expressed here through P₅₀, play significant roles.