Evaluation of residual neuromuscular block using train-of-four and double burst stimulation at the index finger.

We examined the percentage of tactile detection of fade in response to train-of-four (TOF), double burst stimulation3,3 (DBS3,3), or DBS3,2 at the index finger compared with that at the thumb during continuous infusion of vecuronium. One hundred five adult patients were studied. At TOF ratios (T4/T1) of 0.41-0.70, fades in response to TOF were more frequently identified by tactile means at the index finger than at the thumb (58% vs 26%, P < 0.05). Similarly, at TOF ratios of 0.61-0.90, fades in response to DBS3,3 were more frequently detected at the index finger than at the thumb (55% vs 15%, P < 0.05), and at TOF ratios of 0.81-1.00, the percentage of detection of fade in response to DBS3,2 was higher at the index finger than at the thumb (72% vs 40%, P < 0.05). In addition, baseline displacement of the index finger or thumb during tactile assessment of fade in response to neurostimulation was measured videographically. The baseline displacement of the index finger was significantly less than that of the thumb (P < 0.05). In summary, the percentage of tactile detection of fade in response to neurostimulation at the index finger is higher than at the thumb, and the absence of fade in response to DBS3,3 at the index finger is a good indicator of adequate recovery from neuromuscular block. This is probably because of the smaller baseline displacement of the index finger.