Figure 1. Relationship of relative variation of forced vital capacity (FVC) over a 5-year period with the breathing reserve (r2 = 0.887; P < 0.0001) (Panel A) and the alveolar-arterial oxygen pressure gradient [P(A-a)O2] at peak exercise (ρ = -0.781; P < 0.0001) (Panel B) obtained by cardiopulmonary exercise testing. Relationship of relative variation of single-breath diffusion of carbon monoxide across the lung (DLCOsb) over a 5-year period with the breathing reserve (ρ = 0.795; P < 0.0001) (Panel C) and the P(A-a)O2 at peak exercise (ρ = -0.765; P < 0.0001) (Panel D) obtained by cardiopulmonary exercise testing. Correlation was determined by univariate analysis using Spearman's rank correlation (Panels B, C and D), with the exception of the correlation between breathing reserve and relative variations of FVC (logarithmic equation; Panel A).
