Effect of morphology on nanoparticle transport and deposition in human upper tracheobronchial airways

Abstract

Aerosol transport and deposition in human lungs has attracted considerable attention in the past few years, as it has significant value to the study of toxicity consequence as well as therapeutic potential in occupational health and medical applications. In reproducing human tracheobronchial airways, two approaches were frequently taken: (1) anatomical realistic reconstruction through image scans (e.g. CT and MRI) or cadaver casts and (2) mathematical description using simplified models. Strengths and limitations are primarily focused on accuracy, resolution, repeatability, and computational\physical expenses. While both approaches were reported in literature, detailed comparison of aerosol transport and deposition in the two representations were scarcely performed, largely due to the challenge to acquire comprehensive data from the irregular structured airway replicas (approach 1). To fill the gap, the current study performed a numerical comparison of nanoparticle transport and deposition in human upper tracheobronchial airways by using an anatomical realistic reconstruction (through CT scans) and a mathematically simplified airway model. As the first step, the current study was focused on the variation in breathing airflow pattern and the effect towards fate of the inhaled nanoparticles in human upper tracheobronchial airways. The study provided important information to understand geometric sensitivity of nanoparticle modeling in the human tracheobronchial tree and is of significant value to predict the whole lung uptake of inhaled nanoparticles in the human respiratory system.

Detailed computational analysis of flow dynamics in an extended respiratory airway model

“…Alternatively, numerical simulation of air-particle flow in the respiratory airways can resolve the regional airflow dynamics with sufficient spatial and temporal resolution (De Backer et al, 2008;Heenan et al, 2003;Inthavong et al, 2010a;Inthavong et al, 2010b;Xu et al, 2006). By incorporating subject-specific geometric models derived from clinical images, personalised computer models are increasingly used among respiratory modelling studies (Dong et al, 2018;Inthavong et al, 2017;Shang et al, 2018). Previous numerical simulations in pulmonary health have focused mainly on two aspects: establishing particle dosimetry model for inhalation toxicology (Koullapis et al, T 2016;Luo and Liu, 2009) or drug delivery purposes (Inthavong et al, 2011;Kenjereš and Tjin, 2017;Yousefi et al, 2015;Yousefi et al, 2017); and understanding the airway structural effect on airflow dynamics (Inthavong et al, 2009), such as sleep apnoea associated with obstructions in extra-thoracic airways (Cisonni et al, 2015) or airway obstructions in the intrathoracic airway (Sul et al, 2014).…”

A Combined Computational and Experimental Study on Nanoparticle Transport and Partitioning in the Human Trachea and Upper Bronchial Airways

“…An anatomical reconstruction of an adult human tracheobronchial tree up to the 15 th generation ( Fig. 1(a)) was made via CT scans (Shang et al, 2018). A truncation, containing trachea and the main bronchi, was extracted and used for a morphometry comparative study with an idealized airway model developed by Shang et al (2018).…”

“…To fill the gap, Shang et al (2018) performed a numerical comparison of nanoparticle transport and deposition in human upper tracheobronchial airways (trachea and the first bifurcation truncated at five lobar partitions) by using an anatomical realistic reconstruction (through CT scans) and a mathematical simplified airway model. The investigation identified major irregularity (at head airway connection)induced variation in airflow and particle deposition patterns in the trachea, while particle fate in the bronchi were less affected.…”

“…The findings correlated well with that of Zhang and Finlay (2005), though their experiments focused more on effect of cartilaginous rings and particles in the micrometer range. Accounting for this geometric irregularity at head airway connection, a modified idealized airway model (based on that of Shang et al, 2018), closer to morphometry of the anatomical construction, was developed in the current study. Using the anatomical airway model (Shang et al, 2018) as a benchmark, new boundary considerations mimicking lobar bronchi air partition were applied to the newly developed idealized model, and major trachea-irregularity-induced enhancement of nanoparticle deposition was quantified.…”

“…Accounting for this geometric irregularity at head airway connection, a modified idealized airway model (based on that of Shang et al, 2018), closer to morphometry of the anatomical construction, was developed in the current study. Using the anatomical airway model (Shang et al, 2018) as a benchmark, new boundary considerations mimicking lobar bronchi air partition were applied to the newly developed idealized model, and major trachea-irregularity-induced enhancement of nanoparticle deposition was quantified. In particular, flow and particle partitioning in the branching airways, an important postulation for aerosol distribution in whole lung dosimetry modeling (Phalen et al, 2016), was examined, and the detailed flow and particle profiles at five lobar exists were analyzed.…”