Single-Breath Washout Tests to Assess Small Airway Disease in COPD Lucas Boeck, MD, Anna Gensmer, MD, Sylvia Nyilas, MD, Bram Stieltjes, MD, PhD, Thomas J. Re, MD, Michael Tamm, MD, Philipp Latzin, MD, PhD, Daiana Stolz, MD, MPH, FCCP  CHEST  Volume 150, Issue 5, Pages 1091-1100 (November 2016) DOI: 10.1016/j.chest.2016.05.019 Copyright © 2016 American College of Chest Physicians Terms and Conditions

Figure 1 Distribution of SIIIN2 and SIIIDTG in patients with COPD and healthy subjects. SIIIN2 = phase III slope of nitrogen single-breath washout; SIIIDTG = phase III slope of double tracer gas (helium and sulfur hexafluoride) single-breath washout. CHEST 2016 150, 1091-1100DOI: (10.1016/j.chest.2016.05.019) Copyright © 2016 American College of Chest Physicians Terms and Conditions

Figure 2 Association of SIIIN2 and DIIIDTG with lung function parameters in COPD. Dlco = diffusing capacity of the lung for carbon monoxide; RV = residual volume; TLC = total lung capacity. See Figure 1 legend for expansion of other abbreviations. CHEST 2016 150, 1091-1100DOI: (10.1016/j.chest.2016.05.019) Copyright © 2016 American College of Chest Physicians Terms and Conditions

Figure 3 Association of SIIIN2 and DIIIDTG with symptoms, exercise capacity, and CT scans. LAA950 = low-attenuation area less than –950 Hounsfield units; MMRC = modified Medical Research Council dyspnea scale; Spo2 = peripheral oxygen saturation. See Figure 1 and 2 legends for expansion of other abbreviations. CHEST 2016 150, 1091-1100DOI: (10.1016/j.chest.2016.05.019) Copyright © 2016 American College of Chest Physicians Terms and Conditions

Figure 4 Main features of putative phenotypes characterizing large airways (airflow obstruction) and small airways (SIIIN2 and SIIIDTG ventilation inhomogeneity). Allocation is based on data from Table 2 and e-Table 1. VI = ventilation inhomogeneity. See Figure 1, 2, and 3 legends for expansion of other abbreviations. CHEST 2016 150, 1091-1100DOI: (10.1016/j.chest.2016.05.019) Copyright © 2016 American College of Chest Physicians Terms and Conditions