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2628020 
Journal Article 
Abstract 
Prediction of aerosol bolus dispersion in expandable acinar airways using computational fluid dynamics models 
Ma, B; Darquenne, C 
2010 
Yes 
American Journal of Respiratory and Critical Care Medicine
ISSN: 1073-449X
EISSN: 1535-4970 
181 
A3646 
English 
WOS:000208771003004 
is part of a larger document 3452678 Proceedings of the American Thoracic Society 2010 International Conference, May 14-19, 2010, New Orleans
Aerosol dispersion in human airways reflects convective mixing processes in the lung and is thus indicative of lung structure and function. Current knowledge on aerosol dispersion in the human lung relies on indirect measurements and is restricted to dispersion in the whole lung. Previous models using two-dimensional acinar airway models with rigid walls were useful to understand the dispersion process in the distal lung, but predictions only accounted for ~45% of experimental data (J. Aerosol Sci.,34:405-418, 2003). In this study, we built three-dimensional (3D) expandable models of human acinar airways that mimic the dense packing of alveoli found in the acinar region. Models ranged from a single alveolar sac to a symmetrical network of four generations of acinar airways. Using computational fluid dynamics techniques, the transport of 1 micrometer aerosol bolus was simulated in these models, assuming isotropic wall expansion and contraction during breathing. The flow in the models corresponded to a flow rate at the mouth of 500 ml/s. The boluses were introduced at the model inlet at the beginning of a 2-sec inspiration immediately followed by a 3-sec expiration. Aerosol bolus dispersion was calculated as the width at half maximum concentration of the exhaled bolus on a curve of aerosol concentration as a function of exhaled volume. The dispersion increased with the number of airways included in the model. Using the four-generation model, predicted dispersion was ~400 ml, and accounted for ~75% of the experimental estimation of dispersion in the acinar region of the human lung (J. Appl. Physiol., 86:1402-1409, 1999). These results highlight the importance of incorporating wall motion in realistic 3D acinar models. Finally, the difference between our prediction and experiments most likely reflect the effect of ventilation inhomogeneities on aerosol dispersion, a feature not considered in the present models. 
American Thoracic Society 2010 International Conference 
New Orleans, LA 
May 14-19, 2010