Performance of a new hand-held device for exhaled nitric oxide measurement in adults and children

Background: Exhaled nitric oxide ( NO) measurement has been shown to be a valuable tool in the management of patients with asthma. Up to now, most measurements have been done with stationary, chemiluminescence-based NO analysers, which are not suitable for the primary health care setting. A hand-held NO analyser which simplifies the measurement would be of value both in specialized and primary health care. In this study, the performance of a new electrochemical hand-held device for exhaled NO measurements (NIOX MINO) was compared with a standard stationary chemiluminescence unit (NIOX). Methods: A total of 71 subjects ( 6 - 60 years; 36 males), both healthy controls and atopic patients with and without asthma were included. The mean of three approved exhalations ( 50 ml/s) in each device, and the first approved measurement in the hand-held device, were compared with regard to NO readings ( Bland-Altman plots), measurement feasibility ( success rate with 6 attempts) and repeatability (intrasubject SD). Results: Success rate was high (>= 84%) in both devices for both adults and children. The subjects represented a FENO range of 8 - 147 parts per billion (ppb). When comparing the mean of three measurements (n = 61), the median of the intrasubject difference in exhaled NO for the two devices was - 1.2 ppb; thus generally the hand-held device gave slightly higher readings. The Bland-Altman plot shows that the 95% limits of agreement were - 9.8 and 8.0 ppb. The intrasubject median difference between the NIOX and the first approved measurement in the NIOX MINO was - 2.0 ppb, and limits of agreement were - 13.2 and 10.2 ppb. The median repeatability for NIOX and NIOX MINO were 1.1 and 1.2 ppb, respectively. Conclusion: The hand-held device ( NIOX MINO) and the stationary system ( NIOX) are in clinically acceptable agreement both when the mean of three measurements and the first approved measurement ( NIOX MINO) is used. The hand- held device shows good repeatability, and it can be used successfully on adults and most children. The new hand- held device will enable the introduction of exhaled NO measurements into the primary health care.