![Sample our Medicine, Dentistry, Nursing & Allied Health journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/5944/TOC-Subject-Sample-2021-Medicine-Dentistry-Nursing-Allied-Health.jpg"})
Abstract
Current guidelines recommend the single-breath measurement of fractional concentration of exhaled nitric oxide (FENO) at the expiratory flow rate of 50 mL/s as a gold standard. The time profile of exhaled FENO consists of a washout phase followed by a plateau phase with a stable concentration. This study performed measurements of FENO using a chemiluminescence analyzer Ecomedics CLD88sp and an electrochemical monitor NIOX MINO in 82 children and adolescents (44 males) from 4.9 to 18.7 years of age with corticosteroid-treated allergic rhinitis (N = 58) and/or asthma (N = 59). Duration of exhalation was 6 seconds for children less than 12 years of age and 10 seconds for older children. The first aim was to compare the evaluation of FENO-time profiles from Ecomedics by its software in fixed intervals of 7 to 10 seconds (older children) and 2 to 4 seconds (younger children) since the start of exhalation (method A) with the guideline-based analysis of plateau concentrations at variable time intervals (method B). The second aim was to assess the between-analyzer agreement. In children over 12 years of age, the median ratio of FENO concentrations of 1.00 (95% CI: 0.99–1.02) indicated an excellent agreement between the methods A and B. Compared with NIOX MINO, the Ecomedics results were higher by 11% (95% CI: 1–22) (method A) and 14% (95% CI: 4–26) (method B), respectively. In children less than 12 years of age, the FENO concentrations obtained by the method B were 34% (95% CI: 21–48) higher and more reproducible (p < 0.02) compared to the method A. The Ecomedics results of the method A were 11% lower (95% CI: 2–20) than NIOX MINO concentrations while the method B gave 21% higher concentrations (95% CI: 9–35). We conclude that in children less than 12 years of age, the guideline-based analysis of FENO–time profiles from Ecomedics at variable times obtains FENO concentrations that are higher and more reproducible than those from the fixed interval of 2 to 4 seconds and higher than NIOX MINO concentrations obtained during a short exhalation (6 seconds). The Ecomedics FENO concentrations of children more than 12 years of age calculated in the interval of 7 to 10 seconds represent plateau values and agree well with NIOX MINO results obtained during a standard 10-second exhalation.