Is recovery of neuromuscular transmission complete after the use of neostigmine to antagonize block produced by rocuronium, vecuronium, atracurium and pancuronium?

To test if recovery of neuromuscular transmission is complete after the use of neostigmine under standardized conditions, we have measured adductor pollicis mechanical activity in response to 0.1 Hz (twitch height), train-of-four (TOF) and 100 Hz (RF 100 Hz) ulnar nerve stimulations. We studied 56 adult anaesthetized (thiopentone, fentanyl, nitrous oxide in oxygen) patients, allocated randomly to one of four groups (n = 14) to receive rocuronium (group Roc), vecuronium (group Vec), atracurium (group Atr) or pancuronium (group Pan). Recovery of neuromuscular transmission was studied for 15 min after neostigmine 40 micrograms kg-1 was given at 25% recovery of twitch height. Fifteen minutes after antagonism, the TOF ratio was 0.91 (SEM 0.01), 0.88 (0.02) and 0.92 (0.01) (ns), and RF 100 Hz was 0.78 (0.01), 0.79 (0.02) and 0.78 (0.01) (ns) respectively, in patients in groups Roc, Vec and Atr, respectively. In patients in group Pan, TOF ratio and RF 100 Hz were only 0.76 (0.01) and 0.33 (0.04) respectively (P < 0.01, one-way analysis of variance, Duncan's multiple classification range tests). In contrast with pancuronium, antagonism of rocuronium-, vecuronium- and atracurium-induced neuromuscular blocks produced a similar high degree of recovery of neuromuscular transmission.