Figure 1.

Patterns of response to bronchoscopic lung volume reduction (BLVR) therapy in terms of exercise capacity, lung volumes and recoil, and expiratory flows. Pattern 1 produces no change in any objective parameters. Pattern 2 produces a beneficial effect in exercise capacity by altering dynamic hyperinflation during exercise (A) through changes in regional lung impedance, without affecting static lung volumes and recoil (B) or expiratory flows (C). Pattern 3 produces larger changes in exercise capacity by altering both static lung volumes (A and B) and dynamic hyperinflation (A), but because lung recoil is not affected, maximal expiratory flows and FEV₁ (C) do not substantially change. Pattern 4 produces changes in exercise capacity (A) and residual lung volume (B) similar to pattern 3, but also results in an increase in FEV₁ by improving maximal expiratory flows (C) as a result of an increase in recoil pressure.