Comparison of neuromuscular block of atracurium and rocuronium in adults.

We studied the time-course of action of atracurium 0.5 mg kg-1 and rocuronium 0.6 mg kg-1 in 24 healthy adult patients. Anesthesia was induced with thiopentone and sufentanil, and maintained with 50% nitrous oxide and 1% enflurane in oxygen. Neuromuscular transmission was monitored by stimulating the ulnar nerve at the wrist and measuring the acceleration of the thumb using the TOF-Guard accelerograph monitor. Supramaximal stimuli of 0.2 ms duration were applied in a single twitch stimulation mode at 1 Hz frequency until completion of block, and in train-of four (TOF) sequence at 2 Hz every 15 sec thereafter. Onset time was longer with atracurium (mean +/- SD:90 +/- 18 sec) than with rocuronium (49 +/- 6 sec). Clinical duration of action (Tl25) was longer with atracurium (52.3 +/- 7.2 min) than with rocuronium (40.0 +/- 6.4 min). Recovery index (Tl25-Tl75) and time for TOF ratio to recover to 0.75 were 17.8 +/- 4.2 and 73.9 +/- 8.8 min with atracurium, and 13.8 +/- 4.1 and 70.4 +/- 14.1 min with rocuronium. The differences between both groups were statistically significant except the difference in the time for TOF to return to 0.75.