title: Extended analysis of exhaled and nasal nitric oxide for the evaluation of chronic cough.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Section of Respiratory Medicine, Hospital S. Maria della Pietà, Casoria (Naples), Italy. Electronic address: mauromaniscalco@hotmail.com.
authors.forename: Mauro
authors.initials: M
authors.lastname: Maniscalco
authors.affiliation: Section of Respiratory Medicine, Hospital S. Maria della Pietà, Casoria (Naples), Italy.
authors.forename: Stanislao
authors.initials: S
authors.lastname: Faraone
authors.affiliation: Department of Respiratory Medicine, University Federico II, Naples, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Sofia
authors.affiliation: Department of Respiratory Medicine, University Federico II, Naples, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Molino
authors.affiliation: Section of Respiratory Medicine, Department of Medicine and Surgery, University of Salerno, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Vatrella
authors.affiliation: Section of Respiratory Medicine, Hospital S. Maria della Pietà, Casoria (Naples), Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Zedda
mesh_terms: D000328:Adult; D001249:Asthma / Q000150:complications / Q000175:diagnosis / Q000378:metabolism; D001944:Breath Tests / Q000379:methods; D002908:Chronic Disease; D003371:Cough / Q000175:diagnosis / Q000209:etiology / Q000378:metabolism*; D003937:Diagnosis, Differential; D045853:Exhalation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009296:Nasal Cavity / Q000378:metabolism*; D009569:Nitric Oxide / Q000032:analysis*; D015203:Reproducibility of Results; D012189:Retrospective Studies
chemical_list: D009569:Nitric Oxide
keywords: Asthma; Cough; Eosinophilic bronchitis; Exhaled nitric oxide; Upper airways