title: Measurement of fractional order model parameters of respiratory mechanical impedance in total liquid ventilation.
abstract: This study presents a methodology for applying the forced-oscillation technique in total liquid ventilation. It mainly consists of applying sinusoidal volumetric excitation to the respiratory system, and determining the transfer function between the delivered flow rate and resulting airway pressure. The investigated frequency range was f ∈ [0.05, 4] Hz at a constant flow amplitude of 7.5 mL/s. The five parameters of a fractional order lung model, the existing "5-parameter constant-phase model," were identified based on measured impedance spectra. The identification method was validated in silico on computer-generated datasets and the overall process was validated in vitro on a simplified single-compartment mechanical lung model. In vivo data on ten newborn lambs suggested the appropriateness of a fractional-order compliance term to the mechanical impedance to describe the low-frequency behavior of the lung, but did not demonstrate the relevance of a fractional-order inertance term. Typical respiratory system frequency response is presented together with statistical data of the measured in vivo impedance model parameters. This information will be useful for both the design of a robust pressure controller for total liquid ventilators and the monitoring of the patient's respiratory parameters during total liquid ventilation treatment.
authors.affiliation: Department ofMechanical Engineering, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada. alexandre.a.beaulieu@gmail.com
authors.forename: Alexandre
authors.initials: A
authors.lastname: Beaulieu
authors.forename: Dominick
authors.initials: D
authors.lastname: Bossé
authors.forename: Philippe
authors.initials: P
authors.lastname: Micheau
authors.forename: Olivier
authors.initials: O
authors.lastname: Avoine
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Praud
authors.forename: Hervé
authors.initials: H
authors.lastname: Walti
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D003198:Computer Simulation; D004867:Equipment Design; D021061:Liquid Ventilation / Q000295:instrumentation / Q000379:methods*; D008954:Models, Biological; D015203:Reproducibility of Results; D015656:Respiratory Mechanics / Q000502:physiology*; D012756:Sheep; D012815:Signal Processing, Computer-Assisted