A comparison of the neuromuscular blocking effects and reversibility of cisatracurium and atracurium.

The neuromuscular blocking effects and the reversibility of cisatracurium 0.1 or 0.15 mg.kg-1 were compared with those of atracurium 0.5 mg.kg-1 during anaesthesia with propofol, nitrous oxide and isoflurane. Neuromuscular block was monitored using train-of-four stimulation while recording the mechanomyographic response of the adductor pollicis muscle. The block was either allowed to recover spontaneously or was antagonised with neostigmine 50 micrograms.kg-1 at 10% or 25% recovery of the first twitch of the train-of-four. The median times to maximum block were 2.7, 2.2 and 1.5 min following cisatracurium 0.1 and 0.15 mg.kg-1 and atracurium 0.5 mg.kg-1, respectively. After cisatracurium 0.1 mg.kg-1 had been given, the median time to recovery of the train-of-four ratio to 0.8 ('adequate recovery') was 74 min during spontaneous recovery, 48 min after reversal with neostigmine when the first twitch of the train-of-four had returned to 10% of control and 50 min after reversal when the first twitch of the train-of-four had returned to 25% of control. These times for cisatracurium 0.15 mg.kg-1 and atracurium 0.5 mg.kg-1 were 90, 66 and 57 min and 75, 56 and 54 min, respectively. Administration of neostigmine significantly shortened the time to adequate recovery for both drugs but there were no significant differences in the case of either neuromuscular blocking drug between the groups of patients given neostigmine at 10 or 25% recovery of the first twitch of the train-of-four.