Assessing airway aerodynamics and aerosol delivery efficiency across morphologic variants of subglottic stenosis.

BACKGROUND AND OBJECTIVE: Subglottic stenosis profoundly alters upper-airway aerodynamics and inhaled corticosteroid delivery, yet current clinical staging systems inadequately capture the functional impact of stenosis geometry. Specifically, the combined effects of stenosis length and cross-sectional severity on airflow resistance and aerosol deposition remain poorly characterized. This study investigates the impact of stenotic lengths, categorized by McCaffrey staging, and stenotic cross-sectional constrictions, defined by Cotton-Myer system, on airway resistance and aerosol deposition efficiency within the subglottis. METHODS: Three-dimensional anatomically realistic normal airways were reconstructed from oral cavity to trachea using subject-specific radiographic images. Using computational fluid dynamics techniques, we modeled a control airway alongside eight subglottic stenosis variants combining two stenotic lengths representing Stage I (5 mm) and Stage II (15 mm) stenotic lengths from McCaffrey system with four cross‑sectional Grade I-III Cotton-Myer system stenotic constrictions (10%, 30%, 60% and 90%), under laminar (15L/min) and turbulent (60L/min) inhalation. RESULTS: Short, high‑grade stenoses produced sharp area transitions, extreme velocity jets, large wall shear stresses, and up to two‑order‑of‑magnitude increases in total resistance, whereas longer lesions of comparable minimum area generated lower aerodynamic penalties. These orifice-like anatomic structures also maximized subglottic drug particle deposition, particularly under turbulent flow and modified inhaler configurations, while milder or longer stenoses yielded negligible local dose and greater distal penetration. CONCLUSIONS: Findings highlight stenosis length and axial area gradient as critical, yet under‑recognized, determinants of both disease burden and therapeutic targeting, and support patient‑specific flow modeling to guide treatment modality and optimize drug delivery strategies in subglottic stenosis.

Duke Scholars

Author Dennis Onyeka Frank-Ito Rhinology and Skull Base Surgery