Particle deposition in healthy and bronchoconstricted lung

Abstract

Background: Computational Fluid Dynamics (CFD) is a branch of fluid mechanics that uses numerical methods and algorithms to simulate the movement of fluids. Objective: to compare the inhaled particle deposition (PD) in healthy and bronchoconstricted lungs, using CFD. Method: PD was calculated in a healthy lung (trachea diameter 18 mm) and in a lung with airways reduced a 10% (fig1A). Particle conditions were: MMAD 5 µm, flow 18 L/min. PD is determined by the sum of trapped particles at each airway generation. The results were compared to Conway et al (Conway J, Fleming J, Majoral C, et al. Controlled, parametric, individualized, “2D and 3D imaging measurements of aerosol deposition in the respiratory tract of healthy human subjects for model validation”, J Aerosol Sci 2012 Oct; 52: 1–17) using PET and gammagraphy, with a flow of 18 L/min and MMAD of 5.76 µm. Results: PD increases progressively along the airways, both in the healthy and bronchoconstricted lung, but more markedly in the latter case (fig1B). PD is higher in the first generations, due to impaction, and in the latest generations, due to sedimentation. The results obtained by CFD are similar to those obtained experimentally (fig1C). Conclusions:Bronchoconstriction increases the PD in the first generations of the airway, hampering the arrival of drug to the distal airway. CFD allows realistic simulation of drug deposition in the airways, when compared to results obtained by gammagraphy and PET.