Onset and recovery of atracurium and suxsmethonium-induced neuromuscular blockade with simultaneous train-of-four and single twitch stimulation

Abstract

Single twitch and train-of-four stuimulation were applied at 0.08 Hz to each ulnar nerve and the force of contraction of the adductor pollicis was recorded during onset of and recovery from neuromuscular blockade by suxamethonium 1mg kg-1 or atracuirm 0.4 mg kg-1. Times to 90% first twitch blockade of train-of-four were (mean ± SEM) 0.82 ± 0.08 and 1.98 ± 0.18 min for suxmaethonium and atracurium, respectively, compared with times to 90% single twitch blockade of 1.00±0.07 and 3.35 ± 0.37 min, respectively (p < 0.05 in both cases). Apparent onset time also depended on how long train-of-four stimulation had been applied before injection of atracurium. The mode of stimulation had little effect on time to 10% recovery. The results are consitent with stimulation-induced augmentation in muscle blood flow, which increased delivery of the drug to the neuromuscular junction. © 1987 British Journal of Anaesthesia.