Objective: The lung clearance index (LCI), an index of ventilation homogeneity derived from the multiple breath wash out (MBW) of an inert gas, is a lung function test to monitor pulmonary disease. The aim of this study was to investigate whether LCI measurements are suitable for the daily routine in patients with COPD in comparison to young and healthy controls. Methods: MBW measurements were performed successfully in 23 patients (out of 42) patients with COPD (FEV1 %, 40.41 ± 14.65). As controls we selected 30 healthy and young volunteers. All subjects used the EasyOne ProLab™ (ndd, Switzerland). Results: 18 patients were not able to finish measurements successfully because of significant leaks, cough and irregular breathing (GOLD I n=1 (5.6%); GOLD II n=6 (33.3%); GOLD III n=5 (27.7%); GOLD IV n=6 (33.3%). The mean LCI was significantly higher in COPD patients as compared to young and healthy volunteers (12.55 ± 3.50 vs 7.00 ± 1.02, p
