AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Progress in the Development of a Complete-Airway Computational Fluid Dynamics (CFD) Model for Pharmaceutical Aerosols
WORTH LONGEST, Virginia Commonwealth University
Abstract Number: 439 Working Group: Health Related Aerosols
Abstract Computational fluid dynamics (CFD) provides a powerful technique to capture the complex physics of pharmaceutical aerosol delivery. Complete-airway CFD simulations can provide highly detailed results of regional and local aerosol dosimetry, leading to new insights in the performance of current inhalers and the development of new respiratory drug delivery strategies. However, both complete-airway CFD simulations and comparisons of CFD simulations with in vivo data are rare. At Virginia Commonwealth University, we have been developing a complete-airway CFD model of pharmaceutical aerosol delivery for over a decade. Simulations begin at the site of aerosol formation in the inhaler and include all lung regions from the nasal or oral cavity through the alveoli. Use of CFD enables direct incorporation of factors that are important for the deposition of pharmaceutical aerosols including inhaler jet or spray momentum, interaction between the inhaler and mouth-throat geometry, inhalation waveform, airway wall motion, turbulence, heat and mass transfer, charge effects, and droplet size change due to condensation or evaporation including hygroscopicity. Model results in the upper airways have been extensively validated with concurrent in vitro experiments for multiple inhaler types. Recently, complete-airway model results for multiple inhalers across a range of inhalation waveforms were compared with in vivo gamma scintigraphy data in humans. Regional comparisons with 2D gamma scintigraphy included the inhaler, mouth-throat, upper conducting airways (bifurcations B1-B7) and peripheral airways (bifurcations B8 through alveoli). For both a dry powder inhaler (DPI) considered at multiple flow rates (which influence the polydisperse aerosol size distribution) and a soft mist inhaler (SMI), complete-airway predictions across all regions of interest were within approximately 10% of the in vivo data. Based on these findings, complete-airway CFD simulations of pharmaceutical aerosol delivery are possible, compare well with in vivo data, and provide a valuable tool for drug development and toxicological applications.