| Description |
- Objective: Different staging systems have been developed to assess the severity of laryngotracheal stenosis (LTS). In this study, we assess the effects of stenotic length based on the McCaffrey staging system and constriction in cross-sectional area based on the Cotton-Myer system on airway resistance and drug delivery relative to a normal larynx.
Methods: A three-dimensional anatomically realistic normal larynx reconstructed from subject-specific radiographic images was digitally modified to create eight additional LTS models with varying severities of subglottic stenosis. These represented typical combinations of Stage I (5 mm) and Stage II (15 mm) stenotic length from the McCaffrey system and Grade I-III Cotton-Myer system stenotic constrictions (10%, 30%, 60% and 90%), named 5mm10, 5mm30, 5mm60, 5mm90, 15mm10, 15mm30, 15mm60 and 15mm90. Laryngeal airflow was simulated to capture resting inhalation (15 L/min) during orally inhaled drug administration. Aerosol drug transport was then simulated to mimic drug release velocities for ciclesonide (4.26 m/s) and fluticasone (9.19 m/s).
Results: Airway resistance values were more significantly affected by magnitude of stenotic constriction than stenotic length (Resistance: 5mm10 = 0.037 Pa.s/ml versus 15mm10 = 0.036 Pa.s/ml; 5mm90 = 46.027 Pa.s/ml versus 15mm90 = 24.967 Pa.s/ml). At the 5mm stenotic length, drug deposition in the subglottis generally increased with more severe constriction and with a drug particle velocity of 9.19 m/s (Subglottic drug deposition at 9.19 m/s: 5mm10 = 0.053%, 5mm90 = 4.041%).
Conclusion: These preliminary results suggest that resistance and subglottic drug deposition increase in airways with shorter stenotic length and increased stenotic constriction.
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