Effect of postural change on nasal airway and autonomic nervous system established by rhinomanometry and heart rate variability analysis

Background: Clinically, nasal obstruction is experienced frequently in the supine position, and the nasal autonomic nervous system (ANS) may be involved in the mechanism. The central ANS functions at maintaining cardiovascular hemodynamics. However, during postural change, the corresponding changes of the central ANS may simultaneously change the nasal airway as well. In this study, the relationships between nasal ANS and central ANS were explored using rhinomanometry (RMM) and heart rate variability (HRV) analysis between postural changes. Methods: Twelve healthy volunteers aged between 19 and 39 years and without a history of allergic rhinitis or significant nasal anatomic obstruction were enrolled for the study. The nasal airway was measured using RMM in a sitting position and then in a supine position; the electrocardiography was simultaneously recorded. Results: In supine position, the total nasal airflow significantly decreased and the airway resistance significantly increased (p < 0.05, Wilcoxon signed-rank test). The ratio of low frequency power to high frequency (HF) power of HRV that represents sympathetic modulation significantly decreased in the supine position (p < 0.05, Wilcoxon signed-rank test). However, the HF that represents parasympathetic activity did not show significant change with postural change. The correlations of heartbeat interval with total inspiratory airflow and total inspiratory resistance were significant also (p < 0.01, Pearson's correlation). Conclusion: The central ANS activities significantly correlated with changes to the nasal airway during postural change. The central ANS, especially the sympathetic nervous system, may play a role in controlling nasal airway during postural change.