title: Nasal nitric oxide in cystic fibrosis with and without humming.
abstract: BACKGROUND
  Nasal nitric oxide (nNO) values are reduced in patients with cystic fibrosis (CF). Humming during nNO measurement increases nNO values in healthy subjects. Nasal NO is reduced in patients with CF, sinus disease or nasal polyps. Humming nNO values have not been reported in CF patients yet. Our aim was to explore humming nNO values in CF patients and assess whether nNO during humming is a better discriminator than silent nNO measurements in this patient group.
  
  
  METHODS
  In a cross sectional study we measured nNO concentrations in healthy controls (HC) and in CF patients (n = 23 and 31, respectively). The participants held their breath for 10 s while air was passively extracted from one nostril with 700 mL min(-1) for direct NO measurements (NIOX chemiluminescence analyser). Subsequently nNO was measured during humming with the mouth closed for 10 s.
  
  
  RESULTS
  Mean nNO in parts per billion (p.p.b.) (SD) during breath hold was 499 (164) and 240 (139), respectively. The median nNO peak (p.p.b., minimum-maximum) during humming was 1500 (425-4100) for HC and 120 (23-500) for CF. There was a highly significant difference between nNO both with and without humming between CF and HC (P < 0.01). The sensitivity and specificity of nNO for detecting CF were better with humming.
  
  
  CONCLUSIONS
  Nasal NO concentrations with and without humming are significantly decreased in CF. Humming nNO is an excellent discriminator between HC and CF and performs better than silent nNO.
authors.affiliation: Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: V M D
authors.initials: VM
authors.lastname: Struben
authors.forename: W V
authors.initials: WV
authors.lastname: Sewbalak
authors.forename: M H
authors.initials: MH
authors.lastname: Wieringa
authors.forename: C J
authors.initials: CJ
authors.lastname: Mantingh
authors.forename: L M
authors.initials: LM
authors.lastname: van den Toorn
authors.forename: M
authors.initials: M
authors.lastname: Bakker
authors.forename: L
authors.initials: L
authors.lastname: Feenstra
authors.forename: J C
authors.initials: JC
authors.lastname: de Jongste
mesh_terms: D000328:Adult; D001944:Breath Tests / Q000379:methods; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D003550:Cystic Fibrosis / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D015508:Nasal Obstruction / Q000175:diagnosis; D009426:Netherlands / Q000453:epidemiology; D009569:Nitric Oxide / Q000378:metabolism*
chemical_list: D009569:Nitric Oxide