The association of tidal EFL with exercise performance, exacerbations, and death in COPD.

Background: Tidal expiratory flow limitation (EFL) is frequently found in patients with COPD and can be detected by forced oscillations when within-breath reactance of a single-breath is ≥0.28 kPa·s·L. The present study explored the association of within-breath reactance measured over multiple breaths and EFL with 6-minute walk distance (6MWD), exacerbations, and mortality.