Flow and Particle Dispersion in Lung Acini: Effect of Geometric and Dynamic Parameters During Synchronous Ventilation

Area of Science:

• Pulmonary fluid dynamics
• Aerosol science
• Biomedical engineering

Background:

• The human lung's acinar tree features millions of alveoli with changing size and density across generations.
• Airflow velocity and fluid dynamic parameters (Reynolds and Womersley numbers) decrease in deeper lung generations.
• Understanding airflow and particle transport is crucial for lung health and drug delivery.

Purpose of the Study:

• To characterize alveolar airflow patterns and inhaled particle transport during synchronous ventilation.
• To investigate the influence of geometric and dynamic parameters on particle deposition in the acini.
• To provide insights for toxicological risk assessment and pharmaceutical applications.

Main Methods:

• Utilized a simplified in vitro model of an alveolus and bronchiole simulating synchronous ventilation.
• Employed particle image velocimetry to measure airflow patterns under realistic breathing conditions.
• Calculated particle trajectories and deposition statistics for various particle types and parameters.

Main Results:

• Geometric parameters primarily affect velocity magnitudes in the acinar model.
• Dynamic parameters (Reynolds and Womersley numbers) distort flow symmetry and alter velocity magnitudes.
• Dynamic parameters exert a greater influence on particle trajectories and deposition than geometric parameters.

Conclusions:

• Fluid dynamics in the acini are complex, with dynamic parameters playing a key role in particle behavior.
• Findings can enhance risk assessment for inhaled toxic aerosols.
• Results offer improved understanding for developing inhalable therapeutics and optimizing drug delivery in the lungs.