title: Daily home measurements of exhaled nitric oxide in asthmatic children during natural birch pollen exposure.
abstract: BACKGROUND
  Fractional exhaled nitric oxide (FENO) is a sensitive marker of eosinophilic airway inflammation in asthma. Available methods have restricted measurements to the clinic, giving only a snapshot of the disease, which by nature is highly variable.
  
  
  OBJECTIVE
  We sought to investigate the feasibility, repeatability, accuracy, sensitivity, and biologic plausibility of new handheld equipment for FENO measurements. We studied day-to-day home measurements of FENO during the birch pollen season in children with allergy to birch pollen and a history of mild asthma and rhinoconjunctivitis during this season, as well as in nonatopic children.
  
  
  METHODS
  Eleven children with mild asthma and allergy to birch pollen, performed daily home measurements of FENO for 6 weeks before and during the birch pollen season by using a handheld FENO monitor (NIOX MINO). Additionally, FENO (chemiluminescence equipment [NIOX]) and spirometry were measured at the inclusion and completion visit in the clinic. Peak expiratory flow rate (PEFR) and symptoms were recorded daily.
  
  
  RESULTS
  Daily FENO (NIOX MINO) increased significantly (P < .001) with increasing pollen count. FENO (NIOX MINO) and FENO (NIOX) exhibited a correlation coefficient of 0.98, but FENO (NIOX MINO) was significantly higher than FE(NO) (NIOX) (P < .01). PEFR and FEV1 remained unchanged, and few symptoms were recorded.
  
  
  CONCLUSIONS
  Exhaled nitric oxide levels increased significantly during the pollen season, even though the patients reported only few asthmatic symptoms and no change in PEFR or spirometry. Daily measurements of FENO (NIOX MINO) might allow early detection of disease deterioration, and future studies could address such a measure for dynamic treatment strategies.
  
  
  CONCLUSIONS
  This simple handheld device expands the potential use of FENO to a wider group of asthma clinics and even home measurements.
authors.affiliation: Danish Pediatric Asthma Centre, Copenhagen University Hospital.
authors.forename: Signe
authors.initials: S
authors.lastname: Vahlkvist
authors.forename: Marianne
authors.initials: M
authors.lastname: Sinding
authors.forename: Kirsten
authors.initials: K
authors.lastname: Skamstrup
authors.forename: Hans
authors.initials: H
authors.lastname: Bisgaard
mesh_terms: D000293:Adolescent; D000485:Allergens / Q000009:adverse effects / Q000276:immunology; D001249:Asthma / Q000175:diagnosis* / Q000276:immunology / Q000378:metabolism*; D029662:Betula / Q000276:immunology*; D015415:Biomarkers; D002648:Child; D002675:Child, Preschool; D005240:Feasibility Studies; D005260:Female; D006699:Home Care Services; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000032:analysis* / Q000378:metabolism; D011058:Pollen / Q000009:adverse effects / Q000276:immunology*; D015203:Reproducibility of Results; D012648:Self Care; D012680:Sensitivity and Specificity
chemical_list: D000485:Allergens; D015415:Biomarkers; D009569:Nitric Oxide