Influence of neostigmine on the course of neuromuscular blockade with rocuronium or cisatracurium: a randomized, double-blind trial

OBJECTIVES: To compare the time-course of neuromuscular blockade with rocuronium or cisatracurium during intravenous anesthesia, in terms of both the time to spontaneous recovery or time to reversal after administration of neostigmine. MATERIAL AND METHODS: Patients classified as ASA 1-2 were randomized to receive blinded administration of a single injection of twice the 95% effective dose of rocuronium or cisatracurium for general anesthesia, and then neostigmine plus atropine at recovery of the first train-of-4 (TOF) twitch at 5% or 25%, or normal saline solution as placebo at recovery of the first TOF twitch at 25%. The neuromuscular blockade was monitored by acceleromyography. Intergroup comparisons were carried out by Student t test and analysis of variance. RESULTS: Sixty patients were enrolled. Mean (SD) time to onset was faster with rocuronium at (1.04 0.32] minutes) compared with cisatracurium at (2.58 0.81] minutes) and duration was shorter: time to the first twich at 5% was 30 (6.4) minutes with rocuronium and 38.1 (9.7) minutes with cisatracurium. The total duration of blockade (time to the 80% TOF ratio) was also shorter with rocuronium when the neuromuscular blockade was reversed, but there were no differences in the time to block reversal when neostigmine was not used: 62 (18.9) minutes to recovery from the rocuronium blockade vs 66.96 (15.9) minutes to recover from a cisatracurium blockade. A high percentage of patients had less than an 80% TOF ratio at 60 and 90 minutes of administration of the neuromuscular blockerswhen reversal was not used (patients receiving rocuronium, 60% at 60 minutes, and 20% at 90 minutes; patients receiving cisatracurium, 80% at 60 minutes, and 40% at 90 minutes). CONCLUSION: Not antagonizing a rocuronium- or cisatracurium-induced neuromuscular blockade in surgical procedures lasting less than 90 minutes can lead to a high percentaje of residual blockade (TOF ratio <80%).