European journal of applied physiology
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Eur. J. Appl. Physiol. · Nov 2000
Analysis of end-tidal and arterial PCO2 gradients using a breathing model.
The aim of this paper was to analyse the difference between end-tidal carbon dioxide tension (PETCO2) and arterial carbon dioxide tension (PaCO2) at rest and during exercise using a homogeneous lung model that simulates the cyclic feature of breathing. The model was a catenary two-compartment model that generated five non-linear first-order differential equations and two equations for gas exchange. The implemented mathematical modelling described variations in CO2 and O2 compartmental fractions and alveolar volume. ⋯ The pattern of breathing had a significant effect on the PETCO2-PaCO2 difference. The mean (SD) PETCO2-PaCO2 differences simulated using experimental profiles were 0.80 (0.95), 1.65 (0.40), 2.40 (0.20), 3.30 (0.30) and 4.90 (0.20) mmHg, at rest and during exercise at 50, 100, 150 and 200 W, respectively. The relationship between PETCO2-PaCO2 and tidal volume was similar to data published by Jones et al. (J Appl Physiol 47: 954-960, 1979).