Correlations between Lung Clearance Index (LCI) measurements and spirometry in Chronic Obstructive Pulmonary Disease (COPD)

Introduction and Objectives: COPD is a small airway disease associated with ventilation heterogeneity. The LCI is more sensitive than FEV1 in cystic fibrosis however its place in COPD monitoring is unknown. We evaluated the use of the LCI among subjects with COPD comparatively to spirometry, BMI and exacerbation frequency. LCI can be time intensive and therefore we explored the potential of using a shortened LCI to 1/20th concentration. Methods: The LCI was measured by performing a Multiple Breath Washout using a modified photoacoustic Innocor device with 0.2% Sulphur Hexafluoride on subjects with COPD (N=84). The LCI was repeated in triplicate according to ERS/ATS standards. Tests were analysed at 1/40th and 1/20th starting concentration. Spirometry was performed in line with ERS/ATS standards. Correlations were analysed using Pearson correlation and exacerbation frequency was analysed using Poisson regression. Results: 84 subjects were recruited and 80 tests suitable for analysis. There was statistically significant, moderate correlations between LCI1/40th and FEV1 -0.311 (p=0.05), LCI1/40th and GOLD staging 0.309 (p Conclusions: The LCI measures correlate moderately with some measures of spirometry however further research is required to determine responsiveness to therapy in a COPD cohort. LCI at 1/40th and 1/20th starting concentration correlates highly which may encourage clinical use.