TY - JOUR T1 - The validity of shortened multiple breath washout testing using sulphur hexafluoride in the assessment of patients with COPD JF - ERJ Open Research JO - erjor DO - 10.1183/23120541.00379-2020 SP - 00379-2020 AU - Enya Daynes AU - Neil Greening AU - John Owers-Bradley AU - Sally Singh AU - Salman Siddiqui Y1 - 2021/01/01 UR - http://openres.ersjournals.com/content/early/2021/06/11/23120541.00379-2020.abstract N2 - Introduction Chronic Obstructive Pulmonary Disease (COPD) affects the small airways and is associated with ventilation heterogeneity. There is little data on the Multiple Breath Washout (MBW) in patients with COPD particularly the variability over eight weeks, using a shortened sulphur hexafluoride (SF6) washout. This work evaluated the repeatability of the LCI1/40 and LCI1/20 among subjects with COPD and compared to spirometry and clinical markers.Methods The MBW was performed on patients with COPD to determine ventilation heterogeneity globally (Lung Clearance Index (LCI)), at conductive (Scond) and acinar (Sacin) levels. The LCI was repeated in triplicate and measured at a traditional 1/40th washout and retrofitted to a shortened 1/20th end tidal SF6 concentration washout. Tests were repeated after 20 min and eight weeks to determine within and between visit repeatability and compared with spirometry.Results 84 subjects were recruited to perform LCI and spirometry with 20 subjects performing the repeatability protocol. There were weak correlations between FEV1 percent predicted and LCI1/40th r=−0.311 (p=0.02), and LCI1/20th r=−0.40 (p<0.01). The LCI demonstrated excellent within and good between visit repeatability for both a 1/40th and 1/20th washout (ICC≥0.80). There was a statistically significant strong correlation between LCI1/40th and a shortened LCI1/20 0.86 (p<0.01).Conclusions The LCI is repeatable within and between visits. There are weak correlations with measures of spirometry. A shortened LCI1/20th starting concentration correlates highly with a 1/40th washout which may encourage clinical use.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.Conflict of interest: Dr. Greening has nothing to disclose.Conflict of interest: Dr. Owers-Bradley has nothing to disclose.Conflict of interest: S Singh reports that Actegy Ltd funds a commercial trial from which the present data were obtained.Conflict of interest: S. Siddiqui reports advisory boards for and speaker fees from AstraZeneca, GSK, Novartis, Roche, Boehringer Ingelheim, Owlstone Medical, Mundipharma and ERT Medical, outside the submitted work.Conflict of interest: E. Daynes rreports that Actegy Ltd funds a commercial trial from which the present data were obtained. ER -