Prediction of individual cardiac output from measured VO2 and ventilation

A recent comprehensive model of oxygen capture (Kang et al., 2015) allows for a quantitative prediction of VO2, PAO2, PaO2 and SaO2 as a function of gaseous (ventilation VE and PIO2) and blood determinants (cardiac output Q and PvO2). Its predictions being made on average healthy lungs were validated against average physiological data in the literature. The aim of the present study was to apply the same theoretical method at the individual level to obtain respiration determinants that are not measured routinely. The method is tested by searching individual Q from individual VO2 and VE measured in clinical tests. Data of 16 patients, none of whom were diagnosed with cardiac or respiratory diseases, were gathered from pulmonary function and cardiopulmonary exercise tests performed at Univ. Hospital of Cochin in Paris. Then, using individual data of VE, VO2, TLC and hemoglobin concentration, numerical computations were made by means of this theoretical method for two cases: rest and peak exercise. We conclude that comparison between predicted Q and experimental Q, which is deduced from the Fick’s principle with measured PaO2, shows a perfect proportionality (R2 ~ 1) with only a small systematic difference of 10%. This difference may be attributed to overestimation of the value of the capillary time used in the numerical implementation of the theory. Reference M.-Y. Kang, I. Katz., B. Sapoval (2015) Respir. Physiol. Neurobiol. 205:109-119