Internal pressure driven finite element model of a single pulmonary acinus

¹ School of Engineering, University of Leicester, University Road, Leicester, LE1 7RH, UK
² NIHR Leicester Biomedical Research Unit, Glenfield Hospital, Leicester, LE3 9QP, UK
³ Department of Mechanical Engineering, University of Western Macedonia, Bakola & Sialvera Street, Kozani, 50132, Greece

^* Corresponding author: jc702@le.ac.uk

Abstract

A computer simulated, poroelastic, hyperelastic model was developed to replicate the pressure-volume response of a single pulmonary acinus (15^th branch of the respiratory tree and daughter branches) with air flow at its core. An internal pressure driven approach was taken upon a small spherical geometry (99.2 mm³ in volume) representing this small segment of lung parenchyma. A reference porcine tracheal pressure at tidal breathing was adjusted from 1471 Pa to 998 Pa to accommodate for pressure drop, and the pressure of 998 Pa was applied to the model for parametric analysis of its pressure-volume characteristics. In targeting a proportional tidal volume change of approximately 15% while also inducing a pressure-volume hysteresis, material parameters of Young’s modulus of 4 kPa, Poisson’s ratio of 0.4, and a permeability of 5×10^-5 cm³s^-1cm^-2 were identified as suitable. The energy loss over a single pressure-volume cycle for a pulmonary acinus was found to be 6.3×10^-6 J. This model was qualitatively compared to the pressure-volume relationship of the original porcine data source, and then with experimental findings of the material parameters for lung parenchyma in medical literature, demonstrating same-order agreement.