Figure 39-7 Pattern of electrical stimulation and evoked muscle responses to TOF nerve stimulation and double-burst nerve stimulation (i.e., three impulses in each of two tetanic bursts, DBS_3,3 ) before injection of muscle relaxants (control) and during recovery from nondepolarizing neuromuscular blockade. TOF ratio is the amplitude of the fourth response to TOF divided by the amplitude of the first response. DBS_3,3 ratio is the amplitude of the second response to DBS_3,3 divided by the amplitude of the first response. (See text for further explanation.)