Comparison of exhaled nitric oxide analysers

Abstract

Currently no published data are available concerning the comparability of different types of NO analysers, making inter-laboratory comparisons difficult. In two sets of experiments we compared 4 and 5 NO analysers, respectively, from 3 different manufacturers using different calibration regimes: calibration with (1) a separate recommended calibration gas for each analyser, (2) a single low concentration for all (394 ppb), and (3) a single high concentration (12.8 ppm). We measured three subjects with known low (L), moderate (M) and high (H) bronchial exhaled nitric oxide concentrations as well as standard gases (SG). In the first set of experiments, calibration regime 1 resulted in the largest differences between analysers (coefficient of variation (CV) for L, M, H, SG: 0.42, 0.22, 0.20, 0.14). The lowest CV between analysers was observed after calibration 2 (0.34, 0.19, 0.12, 0.02). Very similar results were obtained in the second set of comparisons. Thus, differences between analysers existed, but were mainly due to differences in recommended calibration gases/procedures. Only a small part was explainable by deviations from target flow. These differences need to be taken into account when comparing data between laboratories or replacing the calibration gas of an analyser, as well as for the establishment and interpretation of normal values.

Comparison of two exhaled nitric oxide analyzers: The NIOX MINO hand‐held electrochemical analyzer and the NOA280i stationary chemiluminescence analyzer

“…Previous studies comparing NO analyzers demonstrated that FeNO values could differ depending on the device used for the measurements 15,17,18 . Most studies comparing the NIOX MINO with the NIOX showed that FeNO values measured with the NIOX MINO in grass‐pollen allergic adults, 8 asthmatic adults, 10 asthmatic children during birch‐pollen exposure, 7 and heterogeneous subjects 5,11 were somewhat higher than those measured with the NIOX.…”

Fractional exhaled nitric oxide in asthma: an update

“…Two analysers from the same manufacturer (desktop and hand‐held device) have been approved for clinical use in the European Union and in the USA (desktop 2003; hand‐held device 2007). There is also evidence that between analyser differences may be important, so care has to be given to quality control issues in relation to both the analyser and reference calibration gas 56,57 …”

“…There is also evidence that between analyser differences may be important, so care has to be given to quality control issues in relation to both the analyser and reference calibration gas. 56,57 Chemiluminescence analysers tend to be rather expensive, large and poorly portable, but smaller cheaper portable devices based on an electrochemical cell technique have recently been developed. These demonstrate strong correlations and degree of agreement with the stationary FeNO analyser.…”

Bronchoalveolar lavage, sputum and exhaled clinically relevant inflammatory markers: values in healthy adults

“…Exhalation against resistance (5-20 cm H 2 O) is the preferred method [6,52]. Thirdly, differences in calibration gases may produce differing results, although analysers from different manufacturers show a sufficient comparability for practical purposes if proper calibration is performed [53]. Fourthly, the influence of ambient NO should be taken into account.…”