Inhaled nasopharyngeal nitric oxide concentrations during unilateral nostril breathing – a pilot study

Abstract Objective: To assess the influence unilateral nostril breathing has on mean inhaled nasopharyngeal nitric oxide (NO) concentrations compared with unobstructed bilateral nostril breathing in individuals demonstrating a nasal cycle.Methods: After determining the patent and congested nasal sides in healthy adult volunteers (N=10), and sampling air at both nostrils, a small diameter gas sampling tube was passed along the floor of the nose into the volunteer's patent nostril, until it was stationed in the nasopharynx. Nasopharyngeal NO concentrations were then assessed during normal nasal at-rest tidal breathing during three different nasal breathing states: first both nostrils, then allocated in randomised order, patent side only, and congested side only.Results: Nasopharyngeal NO concentrations were consistently higher on both exhalation and inhalation during unilateral congested side nostril breathing, when compared with unilateral patent side nostril breathing, and breathing through both nostrils.Conclusions: During unilateral nostril breathing, inhaled nasopharyngeal NO concentrations are consistently higher on the congested side of the nose.