The association of nasal patency with small airway resistance in children with allergic and nonallergic rhinitis

Introduction: Allergic rhinitis (AR) is immunologically and morphologically related to disorders in the lower airway. We investigated the relationship between the anatomy of the intranasal cavity and small airway resistance in subjects with nonallergic rhinitis (NAR). Methods: We enrolled 226 children who were 7 years old and participated in the Seongnam Atopy Project 2016. We evaluated nasal patency using acoustic rhinometry to measure the volume of the nasal cavity at 0-5 cm, and measured lung function of the lower airway using an impulse oscillometry system (IOS) and spirometry. We also performed skin prick tests for 18 aero-allergens, and measured blood total eosinophil counts (TEC) and rhinitis symptom scores for the previous month using a visual analog scale (VAS, range: 0-10). Results: We examined 226 children, 71 (31.7%) with AR, and 62 (27.7%) with NAR. Nasal patency in children with AR (median: 8.28 mm³, IQR: 7.07-9.83) was lower than that of healthy children (median: 9.3 mm³, IQR: 7.69-10.64, P=0.011). Multivariate regression analysis showed that nasal patency was inversely associated with IOS resistance at 5 Hz after adjustment for compounding factors (B=-0.005, SE=0.0032, P=0.041). Analysis of NAR subjects, according to quartiles of nasal patency and quartiles of small airway resistance (Rrs5), indicated that nasal patency decreased as Rrs5 increased (linear trend: P50.020). Conclusion: Nasal symptoms and TEC negatively correlated with nasal patency. Children with AR and NAR who had poor nasal patency had increased small airway resistance.