title: Assessment of respiratory mechanical properties with constant-phase models in healthy and COPD lungs.
abstract: This study employs the concept of applying constant-phase models to input respiratory impedance data obtained with the non-invasive Forced Oscillation Technique (FOT) lung function test. Changes in respiratory mechanics from healthy and chronic obstructive pulmonary disease (COPD) diagnosed patients are observed with a four- and a five-parameter constant-phase model. Tissue damping (p<<0.01), tissue elastance (p<0.02) and tissue hysteresivity (p<<0.01) are calculated from the identified model parameters, providing significant separation between healthy and COPD groups. Limitations of the four-parameter constant-phase model are shown in relation to frequency-dependent impedance values within the range 4-48 Hz. The results clearly show that the five-parameter constant-phase model outperforms the four-parameter constant-phase model in this frequency range. The averaged error is 0.02 and 0.04 for healthy subjects in the five-parameter and four-parameter constant-phase models, respectively. The results show that the identified model values are sensitive to variations between healthy and COPD lungs.
authors.affiliation: Ghent University, Dept. of Electrical Energy, Systems and Automation, Technologiepark 913, 9052 Gent, Belgium. clara@autoctrl.UGent.be
authors.forename: Clara
authors.initials: C
authors.lastname: Ionescu
authors.forename: Eric
authors.initials: E
authors.lastname: Derom
authors.forename: Robin
authors.initials: R
authors.lastname: De Keyser
mesh_terms: D000403:Airway Resistance; D000704:Analysis of Variance; D016001:Confidence Intervals; D004548:Elasticity; D006801:Humans; D008168:Lung / Q000502:physiology*; D008875:Middle Aged; D008954:Models, Biological; D010992:Plethysmography, Impedance; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000503:physiopathology*; D015656:Respiratory Mechanics / Q000502:physiology*; D013147:Spirometry; D018709:Statistics, Nonparametric