title: Pendelluft in the bronchial tree.
abstract: Inhomogeneous inflation or deflation of the lungs can cause dynamic pressure differences between regions and lead to interregional airflows known as pendelluft. This work first uses analytical tools to clarify the theoretical limits of pendelluft at a single bifurcation. It then explores the global and regional pendelluft that may occur throughout the bronchial tree in a realistic example using an in silico model of bronchoconstriction. The theoretical limits of pendelluft volume exchanged at a local bifurcation driven by sinusoidal breathing range from 15.5% to 41.4% depending on the relative stiffness of the subtended regions. When nonsinusoidal flows are considered, pendelluft can be as high as 200% inlet tidal volume (Vin). At frequencies greater than 10 Hz, the inertia of the air in the airways becomes important, and the maximal local pendelluft is theoretically unbounded, even with sinusoidal breathing. In a single illustrative numerical simulation of bronchoconstriction with homogenous compliances, the overall magnitude of global pendelluft volume was <2% of the tidal volume. Despite the small overall magnitude, pendelluft volume exchange was concentrated in poorly ventilated regions of the lung, including local pendelluft at bifurcations of up to 13% Vin. This example suggests that pendelluft may be an important phenomena contributing to regional gas exchange, irreversible mixing, and aerosol deposition patterns inside poorly ventilated regions of the lung. The analytical results support the concept that pendelluft may be more prominent in diseases with significant heterogeneity in both resistance and compliance.
authors.affiliation: Massachusetts Institute of Technology, Cambridge, Massachusetts; Massachusetts General Hospital and Harvard Medical School, Department of Anesthesia and Critical Care, Boston, Massachusetts.
authors.forename: Elliot E
authors.initials: EE
authors.lastname: Greenblatt
authors.affiliation: Molecular and Integrative Physiological Science Program, Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts; Division of Sleep Medicine, Departments of Medicine and Neurology, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts;
authors.forename: James P
authors.initials: JP
authors.lastname: Butler
authors.affiliation: Massachusetts General Hospital and Harvard Medical School, Department of Anesthesia and Critical Care, Boston, Massachusetts.
authors.forename: Jose G
authors.initials: JG
authors.lastname: Venegas
authors.affiliation: Massachusetts General Hospital and Harvard Medical School, Department of Anesthesia and Critical Care, Boston, Massachusetts twinkler@mgh.harvard.edu.
authors.forename: Tilo
authors.initials: T
authors.lastname: Winkler
mesh_terms: D003198:Computer Simulation; D006801:Humans; D008168:Lung / Q000502:physiology*; D008954:Models, Biological; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012119:Respiration; D013990:Tidal Volume / Q000502:physiology
keywords: asthma; computational modeling; gas exchange; ventilation distribution; ventilation mechanics