Mathematical modeling of the respiratory system in swine with acute respiratory distress syndrome.

Objective.The objective of this study is to develop a low-order mathematical model of respiratory gas exchange for design and evaluation of physiological closed-loop controlled (PCLC) mechanical ventilation and oxygenation systems, particularly under acute respiratory distress syndrome (ARDS) conditions.Approach.Experimental data from 11 swine subjects undergoing ARDS followed by hemorrhage were used to derive the mathematical model. The animals were ventilated using a PCLC system that regulated inspired oxygen fraction (FiO2), positive end-expiratory pressure (PEEP), and other ventilation parameters. The mathematical model takes metabolic carbon dioxide production rate (V˙CO2), FiO2, and PEEP as inputs and outputs end-tidal CO2pressure (PetCO2), arterial oxygen pressure (PaO2), and oxygen saturation (SaO2).Main results.The mathematical model accurately reproduced observed gas exchange dynamics in ARDS conditions, effectively capturing O2and CO2behavior in response to the controlled ventilation parameters.Significance.The present study focuses on mathematical model development and calibration using experimental data. The current results support its utility in simulating respiratory gas exchange under lung injury conditions. This low-order mathematical model may offer a promising tool for evaluating and designing PCLC mechanical ventilation and oxygenation, with potential applications in controller development and its preclinical testing.