RESUMO
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±8 yrs; 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 (VË(O2)), carbon dioxide output (VË(CO2)), ventilation (VË(E)), tidal volume (V(T)), and end-tidal P(CO2) (PET(CO2)) derived variables were measured breath-by-breath. The % of E correlated with: (1) the ratio V(Tpeak) (r=0.74; p=0.001); (2) the VË(E)/VË(CO2) slope (r=-0.77; p=0.0004); (3) PET(CO2) values at peak exercise (r=0.80; p=0.0001). Also, the %E was strongly predicted by the following exercise equation: %E(EST) = 58.1 + 11.9 × ΔVË(E)/VË(CO2) (r=0.94; p<0.0001). A V(Tpeak)/FEV1 ratio>1 is typically observed in severe E patients; furthermore, the VË(E)/VË(CO2) slope and the PET(CO2peak) values decrease and increase respectively as more as the emphysema is severe.
