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

Tim H.A Stassen,Jim Bartley,David E White

doi:10.1016/j.resp.2021.103734

Abstract

The yogic pranayama technique of unilateral nostril breathing (UNB) has previously demonstrated improvements in language and anxiety in stroke sufferers, as well as reduced blood pressure and increased heart rate in normal healthy adults. The nose typically passes different amounts of air through each nostril with the greater amount of air passing through the ‘patent’ side, and a lesser amount through the ‘congested’ side. Each side of the nose periodically takes turns at carrying the dominant tidal air flow in what is termed the’ nasal cycle’. The nasal sinuses are a rich source of inhaled nitric oxide, a colourless and odourless gas that acts as a bronchodilator, vasodilator, and neurotransmitter. Nasal derived nitric oxide (NO) may contribute to the benefits attributed to UNB. This investigation seeks to assess the influence the nasal cycle has on inhaled nasopharyngeal NO concentrations during UNB by comparing unobstructed bilateral nostril breathing to patent-side and congested-side UNB in healthy individuals demonstrating a nasal cycle.After determining the patent and congested nasal sides in healthy adult volunteers, and sampling air at both nostrils, nasopharyngeal inhaled 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 with only UNB.Nasopharyngeal NO concentrations were found to be consistently higher on both exhalation and inhalation during congested side UNB, when compared with either unilateral patent side UNB or breathing through both nostrils.

Highlights

The nasal cycle, where periodic changes in nasal airway geometry occur, results in a greater tidal nasal air-flow volume passing through one side of the nose: the patent airway, while a lesser volume passes through the other side: the congested airway [1, 2]
During unilateral nostril breathing, inhaled nasopharyngeal Nitric oxide (NO) concentrations are consistently higher on the congested side of the nose
Using a double-sided paired t-tests for all statistical analysis, there was no significant difference in NO concentrations detected at the nasal vestibule between the individual’s patent and congested nostrils during either exhalation (p = 0.3) or inhalation (p = 0.9) breath phases (Table 1)

Summary

Introduction

The nasal cycle, where periodic changes in nasal airway geometry occur, results in a greater tidal nasal air-flow volume passing through one side of the nose: the patent airway, while a lesser volume passes through the other side: the congested airway [1, 2]. The nasal cycle through fluctuation in airflow partitioning between each airway is thought to enable the upper airway to accommodate the contrasting roles of air conditioning and the removal of entrapped contaminants [5]. The increased inhaled NO concentration in the congested side of the nose associated with the nasal cycle, is thought related to reduced airflow [8]. Previous research has investigated nasal NO concentrations in a non-ventilated nose [10], as well as nasal NO concentrations associated with the nasal cycle [8]. These studies found nasal NO concentration is nasal airflow dependent, and pharyngeal NO concentrations correlated negatively to nasal volume

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Conclusion