Parameter estimates in ventilatory mechanics models during induced RDS

Experiments were carried out on the dog in order to evaluate the most suitable characterization of respiratory mechanics both in a normal physiological situation and duing respiratory distress syndrome. Parameters of the classic one-compartment model, the Otis model, and a three-compartment model were estimated during mechanical ventilation using the Powell algorithm and assuming the transpulmonary pressure and mouth airflow as input and output respectively. The results showed a clear difference of behavior between basal and pathological conditions. In the second case, a doubling of total resistance and a halving of total compliance occur. The data obtained from a basal condition during mechanical ventilation can be effectively interpreted by a one-comparatment model whereas, in the pathological case, a two-compartment model seems to be required.