title: Comparing 6 and 10 sec exhalation time in exhaled nitric oxide measurements in children.
abstract: Standard exhalation time for Fractional exhaled Nitric Oxide (FeNO) measurements is 10 sec but this is difficult for young children. Recommended exhalation time for children is 6 sec, but this was never substantiated in literature. We aimed to investigate the agreement between FeNO values measured with exhalation times of 6 and 10 sec and the preference of children for either method. The study population comprised children aged 5-17 years visiting the Pediatric Pulmonology outpatient clinic. FeNO values, measured during 6 (FeNO-6) and 10 (FeNO-10) sec (random order) using the single-breath online (SBOL) technique, were compared. Preferences for exhalation times were related to FVC values. Ninety-eight children (mean age 10.6 years) were included. Median FeNO-6 (15.2 ppb) and FeNO-10 (13.6 ppb) did not differ significantly (P = 0.259). Mean difference between FeNO-6 and FeNO-10 was -0.3 ppb, limits of agreement ranging from -5.8 ppb to +5.3 ppb. Sixty percent of children with a Forced Vital Capacity (FVC) less than 3 L preferred the FeNO-6 method. We found good agreement between FeNO-6 and FeNO-10, so they can be used interchangeably. An exhalation time of 6 sec was preferred by the majority of subjects with a FVC below 3 L.
authors.affiliation: Department of Pediatric Pulmonology, University Medical Center Utrecht, Utrecht, The Netherlands. m.koopman-5@umcutrecht.nl
authors.forename: M
authors.initials: M
authors.lastname: Koopman
authors.forename: H G M
authors.initials: HG
authors.lastname: Arets
authors.forename: C S P M
authors.initials: CS
authors.lastname: Uiterwaal
authors.forename: C K
authors.initials: CK
authors.lastname: van der Ent
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000175:diagnosis* / Q000378:metabolism; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism*; D001944:Breath Tests / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D045853:Exhalation; D005260:Female; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000032:analysis / Q000378:metabolism*; D017060:Patient Satisfaction; D015203:Reproducibility of Results; D013997:Time Factors; D014797:Vital Capacity
chemical_list: D015415:Biomarkers; D009569:Nitric Oxide