Inhalation airflow and ventilation efficiency in subject-specific human upper airways

Area of Science:

• Aerodynamics
• Biomedical Engineering
• Environmental Health

Background:

• Inhaled chemicals pose health risks, necessitating understanding of their transport within human airways.
• Current methods for evaluating chemical deposition and clearance are limited.
• Building ventilation principles offer a novel approach to airway transport analysis.

Purpose of the Study:

• To investigate inhaled chemical transportation time in realistic human airway models.
• To evaluate chemical arrival and staying times using ventilation efficiency metrics.
• To assess the impact of inhalation flow rates on chemical transport dynamics.

Main Methods:

• Numerical simulation of airflow and chemical transport in three human airway models.
• Application of building ventilation indexes: Scale of Ventilation Efficiency 3 (SVE3) and Local Purging Flow Rate (L-PFR).
• Analysis under varying inhalation flow rates to determine arrival and staying times.

Main Results:

• SVE3 trends generally matched predictions, with nasal cavity exceptions due to flow distribution and vortex formation.
• L-PFR variations were influenced by airway structural constraints.
• Inter-subject differences affected index variations with flow rate, but distribution patterns remained consistent.

Conclusions:

• Combining SVE3 and L-PFR aids in engineering applications for assessing relative health impacts of inhaled chemicals.
• While useful for relative risk assessment, precise chemical evaluation requires comprehensive simulations including surface adsorption and realistic respiration.
• The study highlights the potential of ventilation engineering approaches for understanding respiratory health risks.