TY - JOUR T1 - The effect of O<sub>2</sub> and CO<sub>2</sub> cross-sensitivity sensor error in the Eco Medics Exhalyzer D device on measures of conductive and acinar airway function JF - ERJ Open Research JO - erjor DO - 10.1183/23120541.00614-2021 SP - 00614-2021 AU - Jack Bozier AU - Edward Jeagal AU - Paul D. Robinson AU - G. Kim Prisk AU - David G. Chapman AU - Gregory G. King AU - Cindy Thamrin AU - Sandra Rutting Y1 - 2022/01/01 UR - http://openres.ersjournals.com/content/early/2022/02/18/23120541.00614-2021.abstract N2 - Introduction Multiple-breath nitrogen washout (MBNW) test provides important clinical information in obstructive airways diseases. Recently, a significant cross-sensitivity error in the O2 and CO2 sensors of a widely-used commercial MBNW device (Exhalyzer D, Eco Medics AG, Duernten, Switzerland) was detected, which leads to overestimation of N2 concentrations. Significant errors in functional residual capacity (FRC) and lung clearance index (LCI) have been reported in infants and children. This study investigated the impact in adults, and on additional important indices reflecting conductive (Scond) and acinar (Sacin) ventilation heterogeneity, in health and disease.Methods Existing MBNW measurements of 27 healthy volunteers, 20 participants with asthma and 16 smokers were reanalysed using Spiroware software V3.3.1, which incorporates an error correction algorithm. Uncorrected and corrected indices were compared using paired t-tests and Bland-Altman plots.Results Correction of the sensor error significantly lowered FRC (mean difference 9%) and LCI (8%–10%) across all three groups. Scond was higher following correction (11%, 14%, and 36% in health, asthma and smokers, respectively) with significant proportional bias. Sacin was significantly lower following correction in the asthma and smoker groups, but the effect was small (2%–5%) and with no proportional bias.Discussion: The O2 and CO2 cross-sensitivity sensor error significantly overestimated FRC and LCI in adults, consistent with data in infants and children. There was a high degree of underestimation of Scond but minimal impact on Sacin. The presence of significant proportional bias indicates that previous studies will require reanalysis to confirm previous findings and to allow comparability with future studies.FootnotesThis manuscript has recently been accepted for publication in the ERJ Open Research. It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJOR online. Please open or download the PDF to view this article.Disclosures: No conflicts of interest, financial or otherwise, relating to this study are declared by the authors. ER -