Ideal Particle Sizes for Inhaled Steroids Targeting Vocal Granulomas: Preliminary Study Using Computational Fluid...

Area of Science:

• Pulmonology and Otolaryngology
• Biomedical Engineering
• Pharmacology

Background:

• Vocal fold granulomas are benign laryngeal lesions often linked to reflux, intubation, or phonotrauma.
• Current treatments involve inhaled corticosteroids to manage inflammation, with typical particle sizes ranging from 1 to 4 µm.

Purpose of the Study:

• To investigate the deposition patterns of inhaled corticosteroid particles in the larynx and vocal fold granulomas.
• To determine optimal particle sizes for targeting laryngeal lesions using computational fluid dynamics (CFD).

Main Methods:

• A 3D computational model of the adult airway was created from CT scans.
• Virtual vocal fold granulomas of various sizes and positions were incorporated.
• CFD simulations analyzed deposition of inhaled corticosteroid particles (1-20 µm) under inspiratory airflow (30 L/min).

Main Results:

• Laryngeal deposition peaked for particle sizes of 8-10 µm in the normal airway model (2.8%-3.5%).
• Optimal particle sizes for granuloma targeting increased with granuloma size and posterior location, ranging from 6-14 µm.
• A large posterior granuloma showed maximal glottic deposition (10.8%) with 9-µm particles, three times that of the normal model.

Conclusions:

• Increased granuloma size and posterior location correlate with higher glottic deposition and larger optimal particle sizes.
• Inhalers with larger particle sizes, like some dry-powder inhalers, may enhance drug delivery to the larynx for vocal fold granulomas.
• Current commercial inhalers often utilize smaller particles than suggested by these findings for optimal laryngeal deposition.