Micron particle deposition in a tracheobronchial airway model under different breathing conditions.
Summary of "Micron particle deposition in a tracheobronchial airway model under different breathing conditions."
Effective management of asthma is dependent on achieving adequate delivery of the drugs into the lung. Inhalers come in the form of dry powder inhalers (DPIs) and metered dose inhalers (pMDIs) with the former requiring a deep fast breath for activation while there are no restrictions on inhalation rates for the latter. This study investigates two aerosol medication delivery methods (i) an idealised case for drug particle delivery under a normal breathing cycle (inhalation-exhalation) and (ii) for an increased effort during the inhalation with a breath hold. A computational model of a human tracheobronchial airway was reconstructed from computerised tomography (CT) scans. The model's geometry and lobar flow distribution were compared with experimental and empirical models to verify the current model. Velocity contours and secondary flow vectors showed vortex formation downstream of the bifurcations which enhanced particle deposition. The velocity contour profiles served as a predictive tool for the final deposition patterns. Different spherical aerosol particle sizes (3-10μm, 1.55g/cm(3)) were introduced into the airway for comparison over a range of Stokes number. It was found that a deep inhalation with a breath hold of 2s did not necessarily increase later deposition up to the sixth branch generation, but rather there was an increase in the deposition in the first few airway generations was found. In addition the breath hold allows deposition by sedimentation which assists in locally targeted deposition. Visualisation of particle deposition showed local "hot-spots" where particle deposition was concentrated in the lung airway.
Affiliation
School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, PO Box 71, Plenty Road, Bundoora, Victoria 3083, Australia.
Journal Details
This article was published in the following journal.
Name: Medical engineering & physics
ISSN: 1873-4030
Pages:
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/20855226
- DOI: http://dx.doi.org/10.1016/j.medengphy.2010.08.012
Medical and Biotech [MESH] Definitions
Asthma
A form of bronchial disorder with three distinct components: airway hyper-responsiveness (RESPIRATORY HYPERSENSITIVITY), airway INFLAMMATION, and intermittent AIRWAY OBSTRUCTION. It is characterized by spasmodic contraction of airway smooth muscle, WHEEZING, and dyspnea (DYSPNEA, PAROXYSMAL).
Bronchial Hyperreactivity
Tendency of the smooth muscle of the tracheobronchial tree to contract more intensely in response to a given stimulus than it does in the response seen in normal individuals. This condition is present in virtually all symptomatic patients with asthma. The most prominent manifestation of this smooth muscle contraction is a decrease in airway caliber that can be readily measured in the pulmonary function laboratory.
Models, Statistical
Statistical formulations or analyses which, when applied to data and found to fit the data, are then used to verify the assumptions and parameters used in the analysis. Examples of statistical models are the linear model, binomial model, polynomial model, two-parameter model, etc.
Airway Remodeling
The structural changes in the number, mass, size and/or composition of the airway tissues.
Airway Management
Evaluation, planning, and use of a range of procedures and airway devices for the maintenance or restoration of a patient's ventilation.
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