Date of Award
Daniel Felix Ritchie School of Engineering and Computer Science
Corinne S. Lengsfeld, Ph.D.
Aerosol optimization, Lung, Particle deposition
The lower respiratory regions of the lung boast over 900 million alveoli with a combined 85 m2 of surface area of near direct access to the bloodstream. Within the last century the immense potential of the deep lung as a site for the delivery of drugs has begun to be exploited and today pulmonary delivery of aerosolized therapeutic is commonplace. However, the high inter- and intra-patient variability in dosing is almost completely ignored. Currently, no steps are being taken to mitigate the sources of variability beyond injection into the upper airways. This study seeks to prove that a careful selection of a particle size distribution can improve inhaler performance and reliability. In this study, lung morphometry and flow rate were considered to be the uncontrollable sources of inter- and intra-patient variability. Three populations representing different lung geometries were explored: adults aged 14-21 years old, children aged 1-9 years old and adults with severe lung remodeling. The range of flow rates considered was customized to the population based upon normal to severe asthmatic breath rates for that age group. Statistical equations predicting deposition and the MatLab function fmincon, which minimizes an objective function by the manipulation of multiple variables, was used to optimize the particle size distribution. The objective function for fmincon was the coefficient of variation (COV) and the manipulated variables were the defining parameters of the particle size distribution. This investigation demonstrated that current devices favor the healthy adult leaving critical populations such as infants and children with extremely poor deposition efficiency. The optimal particle size distributions for the adult, adult with airway remodeling and child cohorts were monodispersed with mean diameters of 3.6, 2.8 and 1.2 µm respectively. These results prove that one particle size distribution cannot be used to treat the entire population of inhaler users and more attention must be paid to selecting an appropriate size distribution.
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Received from ProQuest
Worden, Renee, "Optimization of Spray Droplet Size for Drug Delivery to the Deep Lung" (2013). Electronic Theses and Dissertations. 715.
Mechanical engineering, Biomedical engineering