Intra-device repeatability of the NIOX-MINO handheld fractional exhaled nitric oxide monitor

Background: The fraction of exhaled nitric oxide has increasingly been used as a non-invasive biomarker of airway inflammation. Current European Respiratory Society recommendations from 1999 state that repeated exhalations are performed until two nitric oxide values agree at the 5% level. In the preceding years, there has been marked advancements in exhaled nitric oxide measurement devices using electrochemical sensors. However, while the intra-repeatability of the NIOX-MINO has been investigated, such data have been largely obtained with subjects without a respiratory condition. Objective: The objective of the current study was to determine the feasibility of only obtaining a single fraction of exhaled nitric oxide measurement by assessing the intra-repeatability of the NIOX-MINO, with a sample representative of the population referred for respiratory assessment by the paediatric respiratory medicine service at the Evelina London Children’s Hospital; due to the relatively high cost to number of sensor uses ratio. Methods: Four-hundred and twenty-one datasets were included (aged 4–17 years) of patients who had paired fraction of exhaled nitric oxide measurements using the NIOX-MINO. The intra-repeatability of the paired fraction of exhaled nitric oxide measurements were analysed using a one-way repeated measures analysis of variance test. Results: No significant difference was observed between the first and second paired fraction of exhaled nitric oxide measurements (p = 0.153). Conclusions: The findings of the current study go further to support the use of a single fraction of exhaled nitric oxide measurement within clinical practice.