Fig. 6. Correlation between respiratory drive (expressed as P0.1) and oxygen consumption (V̇o2) expressed both as absolute values (A ) or normalized for the minimum V̇o2recorded during the decremental pressure support trial (B ). Each symbol represents the average of the values recorded at each level of pressure support. Notice that the relationship is steeper for patients succeeding in the weaning trial (open symbols ), indicating that for the same increase in respiratory drive these patients have a greater increase in V̇o2in comparison with patients failing the trial (filled symbols ). *, P < 0.05.