Stenotic geometry effects on airflow dynamics and respiration for central airway obstruction

Background and Objective: The quantitative relationship between tracheal anatomy and ventilation function can be analyzed by using engineering-derived methods, including mathematical modeling and numerical simulations. In order to provide quantitative functional evaluation for patients with tracheobronchial stenosis, we here propose an aerodynamics-based assessment method by applying computational fluid dynamics analysis on synthetic and patient-specific airway models.Methods: By using 3D reconstruction of tracheobronchial tree and computational fluid dynamics simulations, the aerodynamic environment from the stenotic central airway down to the 4th-6th bifurcation of the tracheobronchial tree is examined in both synthetic and patient-derived models. The effects of stenotic anatomy (the degree of stenosis, stenotic length and location) on the aerodynamic parameters, including pressure drop, areaaverage velocity, volume flow rate, wall shear stress and airflow resistance, are investigated on threedimensional models of tracheobronchial tree.Results: The results from 36 synthetic models demonstrate that 70% constriction marks the onset of a precipitous decrease in airflow relative to a normal airway. The analyses of simulation results of 8 patient-specific models indicate that the Myer-Cotton stenosis grading system can be interpreted in terms of aerodynamics-derived description, such as flow resistance. The tracheal stenosis significantly influences the resistance of peripheral bronchi, especially for patients with severe stenosis.Conclusions: The present study forms a systematic framework for future development of more robust, bioengineering-informed evaluation methods for quantitative assessment of respiratory function of patients with central airway obstruction.

Automated summary

This study proposes an aerodynamics-based assessment method for quantitative functional evaluation of patients with tracheobronchial stenosis. By using computational fluid dynamics analysis on synthetic and patient-specific airway models, the effects of stenotic anatomy on aerodynamic parameters are investigated. The results show that tracheal stenosis significantly influences the resistance of peripheral bronchi, especially for patients with severe stenosis.