Numerical investigation of nanoparticle deposition in the olfactory region among pediatric nasal airways with adenoid hypertrophy

To understand inhaled nanoparticle transport and deposition characteristics in pediatric nasal airways with adenoid hypertrophy (AH), with a specific emphasis on the olfactory region, virtual nanoparticle inhalation studies were conducted on anatomically accurate child nasal airway models. The computational fluid-particle dynamics (CFPD) method was employed, and numerical simulations were performed to compare the airflow and nanoparticle deposition patterns between nasal airways with nasopharyngeal obstruction before adenoidectomy and healthy nasal airways after virtual adenoidectomy. The influence of different inhalation rates and exhalation phase on olfactory regional nanoparticle deposition features was systematically analyzed. We found that nasopharyngeal obstruction resulted in significant uneven airflow distribution in the nasal cavity. The deposited nanoparticles were concentrated in the middle meatus, septum, inferior meatus and nasal vestibule. The deposition efficiency (DE) in the olfactory region decreases with increasing nanoparticle size (1-10 nm) during inhalation. After adenoidectomy, the pediatric olfactory region DE increased significantly while nasopharynx DE dramatically decreased. When the inhalation rate decreased, the deposition pattern in the olfactory region significantly altered, exhibiting an initial rise followed by a subsequent decline, reaching peak deposition at 2 nm. During exhalation, the pediatric olfactory region DE was substantially lower than during inhalation, and the olfactory region DE in the pre-operative models were found to be significantly higher than that of the post -operative models. In conclusions, ventilation and particle deposition in the olfactory region were significantly improved in post-operative models. Inhalation rate and exhalation process can significantly affect nanoparticle deposition in the olfactory region.

Automated summary

This study investigates the transport and deposition characteristics of inhaled nanoparticles in pediatric nasal airways with adenoid hypertrophy (AH), focusing on the olfactory region. Virtual nanoparticle inhalation studies were conducted on anatomically accurate child nasal airway models using computational fluid-particle dynamics (CFPD) method. The results show that nasopharyngeal obstruction leads to uneven airflow distribution and concentration of deposited nanoparticles in specific regions. The deposition efficiency in the olfactory region decreases with increasing nanoparticle size during inhalation. After adenoidectomy, ventilation and particle deposition in the olfactory region are significantly improved. Inhalation rate and exhalation process have a significant impact on nanoparticle deposition in the olfactory region.