Validation of a hand-held exhaled nitric oxide analyzer for use in children

Measurements of exhaled nitric oxide (FENO) may be useful in the diagnosis and management of asthma in children. A new hand-held device (MINO(R), Aerocrine) for measuring FENO has been marketed but has not been validated in a pediatric population. The objective is to validate the MINO(R) against the NIOX(R) analyzer. This was a randomized cross-over study where FENO was measured in a single assessment using the MINO(R) and NIOX(R). Children were recruited from a respiratory clinic and had six attempts to provide a FENO measurement with each analyzer Fifty-five children were enrolled, 33 boys, median age 9 years. A mean FENO value was obtained in 39 children with MINO(R) and 44 with NIOX(R). Paired mean FENO values were obtained in 34 children and the values were higher for the NIOX(R) (mean difference 3.9 ppb limits of agreement -1.1, 8.9). The differences between analyzers became greater at higher FENO values. The first FENO value using the MINO(R) was 24 ppb and the mean of all FENO values using the MINO(R) was 27 ppb (difference not significant). Exhaled NO values were comparable between the two analyzers although there was greater consistency at lower values. The findings of the study do not contradict the manufacturer's recommendation that only one FENO value is required with the MINO(R), however, we suggest that the mean of at least two values should be reported in children.