Fig. 1. (A ) The evolution, since 1970, of the train-of-four ratio (TOFR) threshold used to define the absence of residual paralysis during emergence. (B ) The different clinical tests usually recommended as a function of the TOFR threshold used to define residual paralysis. At present, the TOFR threshold is 0.9–1.0, and no clinical test is able to detect such low-level paralysis. (C ) Qualitative instrumental measurements of TOFR at which tests are no longer associated with fade. AMG = acceleromyography; DBS = double-burst stimulation; MIP = maximum inspiratory pressure; MMG = mechanomyography; TOF = train-of-four.