TY - JOUR T1 - Growth of Nasal-Laryngeal Airways in Children and Their Implications in Breathing and Inhaled Aerosol Dynamics JF - Respiratory Care DO - 10.4187/respcare.02568 SP - respcare.02568 AU - Jinxiang Xi AU - Xiuhua Si AU - Yue Zhou AU - JongWon Kim AU - Ariel Berlinski Y1 - 2013/07/02 UR - http://rc.rcjournal.com/content/early/2013/07/02/respcare.02568.abstract N2 - BACKGROUND: The human respiratory airway undergoes dramatic growth during infancy and childhood, which induces significant variability in airflow pattern and particle depositions. However, deposition studies have typically focused on adult subjects, results of which may not be readily extrapolated to children. OBJECTIVE: To quantify the growth of human nasal-laryngeal airways at early ages, and to evaluate its impact on breathing resistance and respirable aerosol deposition. METHODS: Four image-based nasal-laryngeal models were developed from children of different ages (10-day to 5-year old) and were compared to that of an adult. The airway dimensions were quantified in terms of different parameters (volume, cross-section area, and hydraulic diameter) and of different anatomies (nose, pharynx, and larynx). Breathing resistance and aerosol deposition were computed using a high-fidelity fluid-particle transport model and validated against in vitro measurements in replica casts fabricated from the same airway models. RESULTS: Significant differences in nasal anatomy were observed among the five subjects in both morphology and dimension. The turbinate region appeared to experience the most noticeable growth during the first five years of age. The nasal airway volumes of the 10-day, 7-month, 3-year, and 5-year old subjects were 6.4%, 18.8%, 24.2% and 40.3% that of the adult, respectively. Remarkable inter-group variability was observed in airflow, pressure drop, deposition fraction, and particle accumulation. The CFD predicted pressure drops and deposition fractions were in close agreement with in vitro measurements. CONCLUSIONS: Age effects are significant in both breathing resistance and micrometer particle deposition. The image-CFD coupled method provides an efficient and effective approach in understanding patient-specific airflows and particle deposition, which have important implications in pediatric inhalation drug delivery and respiratory disorder diagnosis. ER -