Respiratory impedance model with lumped fractional order diffusion compartment *

In this work, a revisited model of the respiratory system is proposed comprising a recurrent ladder network and a lumped fractional order diffusion compartment. Identification is performed on 31 healthy subjects. The data for identification has been gathered using the forced oscillation lung function test, which delivers a non- parametric model of the impedance. The ladder network parameters have been identified and a fractional order has been calculated from the recurrent ratios of the respiratory mechanics (resistance and compliance). The results suggest that the proposed model can characterize the respiratory impedance over a long range of frequencies (5-250Hz). In order to check the validity of the diffusion compartment, an illustrative example has been used to see if the fractional order value of the diffusion compartment is sensitive to changes in tissue resistance. The results support the conclusion that this is a reliable parameter to capture the changes in the distal airways.