Background: We investigated vecuronium-induced neuromuscular blockade in patients with continuous epidural lidocaine injection and those without epidural lidocaine.
Methods: Lower thoracic epidural injection of lidocaine was commenced at a rate of 2-3 mg x kg(-1) x h(-1) following its bolus injection (1.5-2 mg x kg(-1)) only in epidural group. Neuromuscular function was monitored by acceleromyographic train-of-four (TOF) responses of the adductor pollicis muscle to ulnar nerve stimulation after induction of general anesthesia.
Results: Neuromuscular block was obtained by vecuronium 0.1 mg x kg(-1) as an intubating dose and was maintained 5-10% of baseline first twitch (T 1) of TOF responses by continuous vecuronium administration. The maximum depression of T 1 response and onset time obtained by vecuronium 0.1 mg x kg(-1) were not different between the groups, but mean clinical duration from administration of the first dose to T 1 recovery to 5% of baseline was significantly prolonged in group with epidural lidocaine (49.5 min), compared to that without lidocaine (32.3 min). Furthermore, maintenance dose of vecuronium obtained in the group with epidural lidocaine (0.034 mg x kg(-1) x h(-1)) was significantly smaller than that in the group without lidocaine (0.060 mg x kg(-1) x h(-1)).
Conclusions: Based on our results, we conclude that lidocaine injected continuously into the epidural space potentiates vecuronium-induced neuromuscular block.