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New method for single‐breath fraction of exhaled nitric oxide measurement with improved feasibility in preschool children with asthma
Author(s) -
HeijkenskjöldRentzhog Charlotte,
KalmStephens Pia,
Nordvall Lennart,
Malinovschi Andrei,
Alving Kjell
Publication year - 2015
Publication title -
pediatric allergy and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.269
H-Index - 89
eISSN - 1399-3038
pISSN - 0905-6157
DOI - 10.1111/pai.12447
Subject(s) - medicine , exhaled nitric oxide , asthma , exhalation , fraction (chemistry) , nitric oxide , pediatrics , anesthesia , spirometry , chromatography , chemistry
Background Respiratory societies recommend use of standardized methodologies for fraction of exhaled nitric oxide (FeNO) measurements in adults and children, but in preschoolers, feasibility remains a problem. The exhalation time needed to obtain steady‐state Fe NO is unclear. Our primary aim was to study the feasibility of an adapted single‐breath Fe NO method with age‐adjusted exhalation times. We also studied the association between time to steady‐state NO level and height, as well as Fe NO in relation to asthma and current treatment with inhaled corticosteroids ( ICS ). Methods Sixty‐three children aged 3–10 years performed Fe NO measurements with a hand‐held electrochemical device with a newly developed flow‐control unit. Exhalation times were pre‐adapted to age. Exhaled air was simultaneously sampled to a chemiluminescence analyzer to measure time to steady‐state NO level. Results Eighty‐one percent of the children achieved at least one approved measurement. From 4 years upwards, success rate was high (96%). Time to steady‐state [NO] (median and interquartile range) was 2.5 s (2.4–3.5) at the age of 3–4 years and 3.5 s (2.7–3.8) at the age of 5–6 years. Height was associated with time to steady state (r 2 = 0.13, p = 0.02). Fe NO (geometric mean [95% CI ]) was higher in ICS ‐naïve asthmatic children (n = 19): 15.9 p.p.b. (12.2–20.9), than in both healthy controls (n = 8) 9.1 p.p.b. (6.6–12.4) and asthmatic subjects on treatment (n = 24) 11.5 p.p.b. (9.7–13.6). Conclusion We found this adapted single‐breath method with age‐adjusted exhalation times highly feasible for children aged 4–10 years. ICS ‐naïve asthmatic children had Fe NO levels under the current guideline cutoff level (20 p.p.b.), highlighting the importance of taking age into account when setting reference values.