162. MULTISCALE AIRFLOW MODEL REPRESENTING HEALTHY AND EMPHYSEMA RAT LUNGS

Department: Mechanical & Aerospace Engineering
Faculty Advisor(s): Alison Marsden | Chantal Darquenne

Primary Student
Name: Jessica M Oakes
Email: jmoakes@ucsd.edu
Phone: 858-210-2858
Grad Year: 2013

Abstract
MULTISCALE AIRFLOW MODEL REPRESENTING HEALTHY AND EMPHYSEMA RAT LUNGS Jessica M. Oakes(1), Alison L. Marsden(1), Celine Grandmont(2), Chantal Darquenne(3), Irene E. Vignon-Clementel(2) (1) Dept of Mechanical and Aerospace Eng, UCSD. (2) INRIA Paris-Rocquencourt (3) Dept of Medicine, UCSD. 1) Introduction: Knowledge of airflow dynamics is essential in understanding the fate of aerosol particles in healthy and diseased lungs. Emphysema is a heterogeneous disease that results in destroyed pulmonary tissue, alveolar space enlargement and oxygen delivery impairment. The pulmonary airflow cannot realistically be solved in 3D for the entire lung, therefore multiscale techniques must be used by coupling 3D Navier-Stokes equations for larger airways and reduced models (0D electric analog) for the rest of the lung. 2) Methods: In this study we used a 0D resistance and capacitance model that represents both the airways and respiratory tissue. The global resistance (R) and capacitance (C) parameters were estimated using experimental data from five healthy and five emphysema rats. Airflow simulations were performed using an in-house 3D finite element solver (SimVascular, simtk.org) on rat airway geometry created from MR images. For both the healthy and emphysema simulations the experimental inlet pressure curve was applied at the inlet. The 0D model was applied at the five outlets with the R and C distributed such that the overall resistance and capacitance of the 3D-0D simulation were the same as those derived from the global 0D model. Seven simulations were performed; 1 healthy, 1 uniform emphysema and 5 different cases of heterogeneous emphysema. In the heterogeneous emphysema cases the disease was confined to a single lobe. 3) Results: The R and C 0D global model parameters were found to be 0.223 0.116 cmH2O&#8722;s/cm3 and 0.253 0.030 cm3/cm H2O, respectively for the healthy rats and 0.180 0.0.53 cmH2O&#8722;s/cm3 and 0.373 0.139 cm3/cm H2O, respectively for the emphysema rats. The capacitance significantly increased in emphysema (p < 0.05), but the resistance did not change. The simulation results showed that the inhaled flow distribution was equal for the healthy and uniform emphysema cases. However, in the heterogeneous emphysema cases the delivery of inhaled air was larger in the diseased lobe. 4) Conclusion: The 3D-0D model described here is the first of its kind to be used to study healthy and emphysema lungs. In the future, the model may be used to study aerosol deposition and distribution.

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