In patients affected by chronic obstructive pulmonary disease (COPD), cardiopulmonary response to exercise was never related to the severity of emphysema (E) measured by high resolution computed tomography (HRCT).

Sixteen patients (age=65±8yrs; FEV(1)=54±18%pred; RV=160±28%pred) with moderate to severe E (quantified by lung HRCT as % voxels<-910 HU) were exercised on a cycle-ergometer to exhaustion. Oxygen uptake [Formula: see text] , carbon dioxide output [Formula: see text] , ventilation (V˙(E)), tidal volume (V(T)), and end-tidal [Formula: see text] ( [Formula: see text] ) derived variables were measured breath-by-breath. The % of E correlated with: (1) the ratio [Formula: see text] (r=0.74; p=0.001); (2) the [Formula: see text] slope (r=-0.77; p=0.0004); (3) [Formula: see text] values at peak exercise (r=0.80; p=0.0001).

Also, the %E was strongly predicted by the following exercise equation: [Formula: see text] (r=0.94; p<0.0001). A [Formula: see text] ratio>1 is typically observed in severe E patients; furthermore, the [Formula: see text] slope and the [Formula: see text] values decrease and increase respectively as more as the emphysema is severe.