Successful Fractional Exhaled Nitric Oxide Measurements with NIOX VERO using 6- and 10-s Exhalation Modes in Children with Asthma Aged 4–10 Years: A Randomized Study

Introduction Fractional exhaled nitric oxide (FeNO) is a valuable tool for measuring allergic airway inflammation in children with asthma, particularly in those for whom other tests are difficult to perform. The use of a 6-s exhalation time (6-s mode) rather than 10 s (10-s mode) used for adults is in line with current recommendations, making FeNO a feasible option for younger children. However, sparse data are available that demonstrate the agreement between exhalation modes in young children. Methods This study assessed the degree of agreement of FeNO measured using the 6- and 10-s modes in young children (6–10 years) with asthma and the feasibility of use in younger children (4–5 years) with asthma using the NIOX VERO® analyzer. Enrolment was stratified so that 15 subjects had FeNO > 35 ppb and 35 had FeNO < 35 ppb. Results For subjects aged 6–10 years, agreement and repeatability was shown with mean observed FeNO measurements of 34.36 ppb (6-s mode) and 33.35 ppb (10-s mode) and paired differences were centered close to 0 (median 0.50). In the 4–5-year age group, ten subjects had a valid 6-s mode FeNO result (mean value, 12.6 ppb) of which seven (70%) also had a valid 10-s mode FeNO result (mean value, 10.6 ppb) with good correspondence in FeNO results between the modes. Conclusions Children aged 4–10 years can successfully perform FeNO measurements using the NIOX VERO® analyzer in the 6-s or the 10-s modes. FeNO measurements were repeatable and consistent with a high degree of agreement between the two modes in children aged 6–10 years. Younger children (4–5 years) also successfully performed FeNO measurements using both modes and were more successful using the 6-s mode. Thus, in young children, successful FeNO measurements can be obtained, providing physicians with important information in this age group to aid in the diagnosis and treatment of asthma. Funding Aerocrine Inc (now Circassia Pharmaceuticals Inc).