title: Unsteady diffusional screening in 3D pulmonary acinar structures: from infancy to adulthood.
abstract: Diffusional screening in the lungs is a physical phenomenon where the specific topological arrangement of alveolated airways of the respiratory region leads to a depletion, or 'screening', of oxygen molecules with increasing acinar generation. Here, we revisit diffusional screening phenomena in anatomically-inspired pulmonary acinar models under realistic breathing maneuvers. By modelling 3D bifurcating alveolated airways capturing both convection and diffusion, unsteady oxygen transport is investigated under cyclic breathing motion. To evaluate screening characteristics in the developing lungs during growth, four representative stages of lung development were chosen (i.e. 3 months, 1 year and 9 months, 3 years and adulthood) that capture distinct morphological acinar changes spanning alveolarization phases to isotropic alveolar growth. Numerical simulations unveil the dramatic changes in O2 transport occurring during lung development, where young infants exhibit highest acinar efficiencies that rapidly converge with age to predictions at adulthood. With increased ventilatory effort, transient dynamics of oxygen transport is fundamentally altered compared to tidal breathing and emphasizes the augmented role of convection. Resolving the complex convective acinar flow patterns in 3D acinar trees allows for the first time a spatially-localized and time-resolved characterization of oxygen transport in the pulmonary acinus, from infancy to adulthood.
authors.affiliation: Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa, 32000, Israel.
authors.forename: Philipp
authors.initials: P
authors.lastname: Hofemeier
authors.affiliation: Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa, 32000, Israel.
authors.forename: Lihi
authors.initials: L
authors.lastname: Shachar-Berman
authors.affiliation: Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa, 32000, Israel.
authors.forename: Janna
authors.initials: J
authors.lastname: Tenenbaum-Katan
authors.affiliation: INSERM, U955 (Equipe 13) and CNRS ERL 7240, Cell and Respiratory Biomechanics, Universit Paris-Est, 94010 Crteil, France; Physique de la Matire Condense, Ecole Polytechnique, CNRS, 91128 Palaiseau, France.
authors.forename: Marcel
authors.initials: M
authors.lastname: Filoche
authors.affiliation: Department of Biomedical Engineering, Technion - Israel Institute of Technology, Haifa, 32000, Israel. Electronic address: sznitman@bm.technion.ac.il.
authors.forename: Josué
authors.initials: J
authors.lastname: Sznitman
mesh_terms: D000328:Adult; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D008168:Lung / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology*; D008954:Models, Biological; D009068:Movement; D012119:Respiration
keywords: Developing acini; Diffusional screening; Oxygen transport; Pulmonary flows