Regional aerosol deposition in the human airways: The SimInhale benchmark case and a critical assessment of in silico methods

Abstract

Regional deposition effects are important in the pulmonary delivery of drugs intended for the topical treatment of respiratory ailments. They also play a critical role in the systemic delivery of drugs with limited lung bioavailability. In recent years, significant improvements in the quality of pulmonary imaging have taken place, however the resolution of current imaging modalities remains inadequate for quantifying regional deposition. Computational Fluid-Particle Dynamics (CFPD) can fill this gap by providing detailed information about regional deposition in the extrathoracic and conducting airways. It is therefore not surprising that the last 15years have seen an exponential growth in the application of CFPD methods in this area. Survey of the recent literature however, reveals a wide variability in the range of modelling approaches used and in the assumptions made about important physical processes taking place during aerosol inhalation. The purpose of this work is to provide a concise critical review of the computational approaches used to date, and to present a benchmark case for validation of future studies in the upper airways. In the spirit of providing the wider community with a reference for quality assurance of CFPD studies, in vitro deposition measurements have been conducted in a human-based model of the upper airways, and several groups within MP1404 SimInhale have computed the same case using a variety of simulation and discretization approaches. Here, we report the results of this collaborative effort and provide a critical discussion of the performance of the various simulation methods. The benchmark case, in vitro deposition data and in silico results will be published online and made available to the wider community. Particle image velocimetry measurements of the flow, as well as additional numerical results from the community, will be appended to the online database as they become available in the future.

Targeting inhaled aerosol delivery to upper airways in children: Insight from computational fluid dynamics (CFD)

“…A notable signature of the flow is the formation of a laryngeal jet in the presence of the larynx constriction; a feature previously discussed [ 40 , 83 ]. Numerical simulations have shown that the larynx is an important anatomical element that influences aerosol deposition outcomes [ 84 ]: flow acceleration due to the constriction coupled with directional changes due to anatomy contribute to enhanced aerosol deposition near the larynx [ 83 ]. Here, the laryngeal jet is observed across all age points at PIFR, with a peak velocity magnitude reaching a local maximum in the vicinity of the larynx contraction.…”

Characterising viable virus from air exhaled by H1N1 influenza-infected ferrets reveals the importance of haemagglutinin stability for airborne infectivity

“…Airflow into the IVTT was modelled as a laminar round jet [47], and a Lagrangian particletracking algorithm adopted to compute the droplet trajectories [48]. The forces acting on the droplets were taken to be drag and gravity, which are the dominant forces for aerosol particles in the micrometre range [49]. The change in droplet size and temperature resulting from evaporation of water to the surrounding air was also taken into account, based on previous modelling approaches for soluble aerosol particles [50,51].…”

Targeted Drug Delivery to Upper Airways Using a Pulsed Aerosol Bolus and Inhaled Volume Tracking Method

“…These can be described using two non-dimensional particle numbers, namely the Stokes and gravity numbers [10]. We note that a detailed discussion of ensuing air flow patterns in the modeled respiratory tract is omitted here for brevity; flow topologies qualitatively resemble extensive works on the topic [39, 40]. However, for an intubated patient the abrupt diameter change from the tip of the intubation tube to the trachea (Fig.…”