Response of nasal airway and heart rate variability to controlled nasal breathing.

To investigate the responses of nasal airway and autonomic nervous system (ANS) under controlled nasal breathings. Ten healthy volunteers, aged between 21 and 37 years, were enrolled. The participants breathed either through bilateral nostrils (BNB) or unilaterally through the left nostril (UNB) at 0.25 Hz for 5 min. The electrocardiography was simultaneously recorded and the ANS activities were evaluated using heart rate variability analysis. Nasal airway resistance and related factors were measured by rhinomanometry. The results showed that the mean heartbeat interval during UNB was significantly greater than during BNB. The sympathetic modulation decreased significantly during UNB. The correlations between nasal airway resistance and mean heartbeat interval were significant for both UNB and BNB. The increase of heartbeat intervals during UNB was associated with the decrease of cardiac sympathetic activities. The changes of ANS activities and nasal airway resistance during UNB are similar to the changes caused by a prolonged lying.