BACKGROUND: Assessment of eosinophilic airway inflammation may be helpful in the management of asthma. Nitric oxide (NO) has potential advantages as a tool to monitor airway inflammation although little is known about the relationship between NO and eosinophilic airway inflammation and the factors which influence it. METHODS: We set out to define the relationship between exhaled NO and the sputum eosinophil count, identify the exhaled NO concentration that best identified a sputum eosinophil count >3% and investigate the impact of several potential confounding factors in 566 consecutive patients with varying severity of asthma. Finally we examined the ability of exhaled NO concentrations measured at differing exhalation flows to identify the presence of a sputum eosinophilia. RESULTS: We found a significant positive relationship between exhaled NO and sputum eosinophil count (R(2)=0.26, P<0.001) which was best described using a non-linear model. There were no clinically important confounding factors to this model. In non-smokers an exhaled NO concentration of >8.3 p.p.b. at 250 mL/s gave 71% sensitivity and 72% specificity for identifying a sputum eosinophil count of >3%. CONCLUSIONS: This value of exhaled NO would seem to be the best for identifying significant eosinophilic airway inflammation. It is applicable to a wide range of non-smoking patients with asthma; exhalation flow does not alter the ability of exhaled NO concentration to detect a sputum eosinophilia.
BACKGROUND: Assessment of eosinophilic airway inflammation may be helpful in the management of asthma. Nitric oxide (NO) has potential advantages as a tool to monitor airway inflammation although little is known about the relationship between NO and eosinophilic airway inflammation and the factors which influence it. METHODS: We set out to define the relationship between exhaled NO and the sputum eosinophil count, identify the exhaled NO concentration that best identified a sputum eosinophil count >3% and investigate the impact of several potential confounding factors in 566 consecutive patients with varying severity of asthma. Finally we examined the ability of exhaled NO concentrations measured at differing exhalation flows to identify the presence of a sputum eosinophilia. RESULTS: We found a significant positive relationship between exhaled NO and sputum eosinophil count (R(2)=0.26, P<0.001) which was best described using a non-linear model. There were no clinically important confounding factors to this model. In non-smokers an exhaled NO concentration of >8.3 p.p.b. at 250 mL/s gave 71% sensitivity and 72% specificity for identifying a sputum eosinophil count of >3%. CONCLUSIONS: This value of exhaled NO would seem to be the best for identifying significant eosinophilic airway inflammation. It is applicable to a wide range of non-smoking patients with asthma; exhalation flow does not alter the ability of exhaled NO concentration to detect a sputum eosinophilia.
Authors: M Diane Lougheed; Catherine Lemiere; Francine M Ducharme; Chris Licskai; Sharon D Dell; Brian H Rowe; Mark Fitzgerald; Richard Leigh; Wade Watson; Louis-Philippe Boulet Journal: Can Respir J Date: 2012 Mar-Apr Impact factor: 2.409
Authors: Erika Garcia; Yue Zhang; Edward B Rappaport; Kiros Berhane; Patrick Muchmore; Philip E Silkoff; Noa Molshatzki; Frank D Gilliland; Sandrah P Eckel Journal: Eur Respir J Date: 2020-07-02 Impact factor: 16.671
Authors: Douglas C Cowan; D Robin Taylor; Laura E Peterson; Jan O Cowan; Rochelle Palmay; Avis Williamson; Jef Hammel; Serpil C Erzurum; Stanley L Hazen; Suzy A A Comhair Journal: J Allergy Clin Immunol Date: 2014-12-06 Impact factor: 10.793
Authors: Mehrab Nasirikenari; E V Chandrasekaran; Khushi L Matta; Brahm H Segal; Paul N Bogner; Amit A Lugade; Yasmin Thanavala; James J Lee; Joseph T Y Lau Journal: J Leukoc Biol Date: 2009-12-09 Impact factor: 4.962