Extended analysis of exhaled and nasal nitric oxide for the evaluation of chronic cough.

Chronic cough is usually defined as a cough that lasts for eight weeks or longer. Its etiological diagnosis is not always straightforward, and the measurement of exhaled nitric oxide (FeNO) has been proposed in patients' evaluation. No studies have assessed the usefulness of extended exhaled NO measurement for the evaluation of chronic cough. Therefore, we aimed at evaluating the usefulness of an extended exhaled NO measurement and nasal NO for an initial evaluation of chronic cough. We studied 52 non-smoker patients with prolonged cough lasting more than eight weeks. Etiologies of cough were identified. Nasal NO and FeNO were assessed using multiple single-breath NO analysis at different constant expiratory flow-rates. From the fractional NO concentration measured at each flow-rate, the total NO flux between tissue and gas phase in the bronchial lumen (J'awNO), and the alveolar NO concentration (Cano) were extrapolated. The patients were classified in four categories: cough variant asthma (CVA), nonasthmatic eosinophilic bronchitis (NAEB), upper airway cough syndrome (UACS) and gastro-esophageal reflux disease (GERD). Compared with UACS and GERD, both exhaled NO and J'awNO were higher in CVA and NAEB, and no differences were found in Cano and nasal NO level among the four groups. Our study suggests a potentially useful role for FeNO measurement in the etiological diagnosis of chronic cough. We did not find any additive value of performing exhaled NO at multiple flow-rates and nasal NO measurements.

Maniscalco M ，Faraone S ，Sofia M ，Molino A ，Vatrella A ，Zedda A ... -  《-》

Exhaled nitric oxide measurement is useful for the exclusion of nonasthmatic eosinophilic bronchitis in patients with chronic cough.

Oh MJ ，Lee JY ，Lee BJ ，Choi DC ... -  《CHEST》

[Values of fractional exhaled nitric oxide in the diagnosis of chronic cough].

Zhang YM ，Lin JT ，Su N ，Chen X ，Liu GL ，Yu HX ，Nong Y ，Zhang XY ，Yang M ，He J ，Li YM ... -  《-》

Validity of fractional exhaled nitric oxide and small airway function indices in diagnosis of cough-variant asthma.

Feng-Jia C ，Xin-Yan H ，Geng-Peng L ，Yang-Li L ，Can-Mao X ... -  《-》

Diagnostic accuracy of fractional exhaled nitric oxide measurement in predicting cough-variant asthma and eosinophilic bronchitis in adults with chronic cough: A systematic review and meta-analysis.

Individual studies have suggested the utility of fractional exhaled nitric oxide (Feno) measurement in detecting cough-variant asthma (CVA) and eosinophilic bronchitis (EB) in patients with chronic cough. We sought to obtain summary estimates of diagnostic test accuracy of Feno measurement in predicting CVA, EB, or both in adults with chronic cough. Electronic databases were searched for studies published until January 2016, without language restriction. Cross-sectional studies that reported the diagnostic accuracy of Feno measurement for detecting CVA or EB were included. Risk of bias was assessed with Quality Assessment of Diagnostic Accuracy Studies 2. Random effects meta-analyses were performed to obtain summary estimates of the diagnostic accuracy of Feno measurement. A total of 15 studies involving 2187 adults with chronic cough were identified. Feno measurement had a moderate diagnostic accuracy in predicting CVA in patients with chronic cough, showing the summary area under the curve to be 0.87 (95% CI, 0.83-0.89). Specificity was higher and more consistent than sensitivity (0.85 [95% CI, 0.81-0.88] and 0.72 [95% CI, 0.61-0.81], respectively). However, in the nonasthmatic population with chronic cough, the diagnostic accuracy to predict EB was found to be relatively lower (summary area under the curve, 0.81 [95% CI, 0.77-0.84]), and specificity was inconsistent. The present meta-analyses indicated the diagnostic potential of Feno measurement as a rule-in test for detecting CVA in adult patients with chronic cough. However, Feno measurement may not be useful to predict EB in nonasthmatic subjects with chronic cough. These findings warrant further studies to validate the roles of Feno measurement in clinical practice of patients with chronic cough.

Song WJ ，Kim HJ ，Shim JS ，Won HK ，Kang SY ，Sohn KH ，Kim BK ，Jo EJ ，Kim MH ，Kim SH ，Park HW ，Kim SS ，Chang YS ，Morice AH ，Lee BJ ，Cho SH ... -  《-》