title: Acinar and conductive ventilation heterogeneity in severe CF lung disease: back to the model.
abstract: Severe convective ventilation heterogeneity occurring in CF lung disease requires a modified method to determine acinar and conductive components of ventilation heterogeneity from normalized phase III slope (Sn) curves. Modified Sacin* and Scond* (as opposed to standard Sacin and Scond) are proposed and interpreted on the basis of 2 conceptual mechanisms: (a) flow asynchrony between two convection-dependent units with a different specific ventilation, but with an identical acinus inside each unit (generating an identical diffusion-convection-dependent portion of Sn); (b) different specific ventilation (without any flow asynchrony) between two convection-dependent units with the worst ventilated unit containing an abnormal acinus generating the greatest diffusion-convection-dependent portion of Sn. In CF patients with an abnormal lung clearance index (LCI), Scond* (but not Scond) and Sacin* were significant contributors to LCI (β(Scond*)=0.70; β(Sacin*)=0.49; P<0.001 for both). Mechanism (a) can entirely account for experimental Scond* values, while mechanism (b) implies that experimental Sacin* values are likely dominated by peripheral ventilation heterogeneity in the best ventilated portions of the lung.
authors.affiliation: Respiratory Division, University Hospital UZ Brussel, Brussels 1090, Belgium. sylvia.verbanck@uzbrussel.be
authors.forename: Sylvia
authors.initials: S
authors.lastname: Verbanck
authors.forename: Manuel
authors.initials: M
authors.lastname: Paiva
authors.forename: Daniel
authors.initials: D
authors.lastname: Schuermans
authors.forename: Anne
authors.initials: A
authors.lastname: Malfroot
authors.forename: Walter
authors.initials: W
authors.lastname: Vincken
authors.forename: Eef
authors.initials: E
authors.lastname: Vanderhelst
mesh_terms: D000328:Adult; D000886:Anthropometry; D001985:Bronchial Provocation Tests; D016022:Case-Control Studies; D003198:Computer Simulation; D003550:Cystic Fibrosis / Q000150:complications*; D005260:Female; D006801:Humans; D008168:Lung / Q000473:pathology; D008171:Lung Diseases / Q000175:diagnosis* / Q000209:etiology*; D008297:Male; D008954:Models, Biological; D012123:Pulmonary Ventilation / Q000502:physiology*; D055815:Young Adult