No abstract

RATIONALE: This study, conducted using the NIOX VERO, assessed the feasibility and degree of agreement between FeNO measurements performed in the same subject using both 6 second (6s) and 10 second (10s) exhalation modes in young children. METHODS: This randomized, multi-center, single-visit, study was conducted in asthmatic and non-asthmatic children 4 to 6 years of age. Subjects were randomized to perform FeNO measurements with either the 6s or 10s exhalation mode first. Degree of agreement was measured through assessment of the bias at the 35ppb cutoff using a weighted Deming Regression analysis in subjects that completed two FeNO measurements in both modes. RESULTS: 193/247 subjects completed at least one FeNO measurement in either mode. There were 68 subjects with two measurements in both modes. Average FeNO for the 6s mode was 21.1 (SD514.76) ppb and 20.7 (SD514.59) ppb in the10s mode. The observed paired difference was 0.4 (SD53.41) ppb. The estimated intercept and slope from the weighted Deming regression were not significantly different from 0 (p50.762) and 1.0 (p50.653), respectively. Average bias in the predicted 6s mode FeNO results was low (1.03%), and bias at the 35 ppb cutoff value (0.391) was significantly < 7 ppb (20% of 35 ppb; p<0.0001). No adverse events or serious injuries were reported. CONCLUSIONS: The degree of agreement between the 6s and the 10s modes was high. Results from this study support reliable and safe use of the NIOX VERO to measure FeNO in 4-6 year old children.