Correlation between maximum inspiratory pressure and inspiratory load compensation (ILC) ventilatory variables in the 16 difficult-to-wean subjects, prior to inspiratory muscle strength training (IMST), with a 10 cm H2O load. Before IMST the maximum inspiratory pressure in the subjects who ultimately weaned from mechanical ventilation after IMST (shaded data points) significantly correlated with peak inspiratory flow (r = 0.64, P = .008), and there was trend in inspired VT (r = 0.45, P = .08). The white data points represent the subjects who failed to wean. In contrast, no linear relationship was found between maximum inspiratory pressure and inspiratory or expiratory timing during ILC.