Nasal contribution to exhaled nitric oxide at rest and during breathholding in humans

Author: B Kimberly1, B Nejadnik, G D Giraud, W E Holden
1 Medical Service, Portland Veterans Administration Medical Center, Oregon 97201, USA.
Conference/Journal: Am J Respir Crit Care Med
Date published: 1996 Feb 1
Other: Volume ID: 153 , Issue ID: 2 , Pages: 829-36 , Special Notes: doi: 10.1164/ajrccm.153.2.8564139. , Word Count: 192

We characterized the nasal contribution to exhaled nitric oxide (NO) at rest and during breathholding in humans. Exhaled NO was greater during nose breathing (141 +/- 17 nl/min/M2, mean +/- SEM) compared with mouth breathing (68 +/- 6 nl/min/M2, n = 8, p < 0.001). After voluntary closure of the soft palate (VCSP) to eliminate nasal NO, exhaled NO from the mouth decreased further (30 +/- 4 nl/min/M2, p < 0.001). Release of NO into nasal passages during VCSP (217 +/- 19 nl/min/M2) was greater than exhaled NO during nasal breathing (141 +/- 17 nl/min/m2, p < 0.001), suggesting that nasal NO is taken up by the respiratory tract. During mouth breathing or nose breathing, NO concentrations sampled with a bronchoscope were higher in the nasopharynx than at the epiglottis or in the trachea in five subjects. Increased peak exhaled NO after a breathhold (33 +/- 7 ppb) was reduced (10 +/- 4 ppb, p < 0.001) after balloon occlusion of the nasopharynx. NO concentration during breathholding increased to a greater extent in the nasopharynx than in the pharynx or trachea. We conclude that the majority of exhaled NO at rest and during a breathhold originates in the nasopharynx.

PMID: 8564139 DOI: 10.1164/ajrccm.153.2.8564139