Differential effects of vecuronium on the thumb and great toe as measured by accelography and electromyography

We evaluated possible differential effects of vecuronium on the thumb and great toe using two types of neuromuscular transmission monitor. Train-of-four stimuli were simultaneously applied to the ulnar nerve and tibial nerves using cutaneous electrodes. The responses were quantified with accelographs (thumb and left great toe) and an electromyograph (right great toe). Twenty ASA 1 or 2 patients received, by random allocation, one of two types of anaesthesia: neuroleptanaesthesia or sevoflurane-based anaesthesia. With both techniques, the shortest time to maximum block after vecuronium 0.1 mg.kg-1 occurred in the thumb as measured by accelography. The average (SD) values with neuroleptanaesthesia were: 173(23) s for thumb using accelography; 220(16) s for great toe using accelography; 205(44) s for great toe using electromyography. The average (SD) value(s) with sevoflurane-based anaesthesia were: 137(15) for thumb using accelography; 179(21) for great toe using accelography; 153(23) for great toe using electromyography. The differences between the thumb and great toe were statistically significant during both types of anaesthesia when measured with the accelograph (p < 0.01). The time from completion of maximal block to 25% recovery of twitch height in the thumb was significantly longer than that of the great toe as measured by accelography during both types of anaesthesia (p < 0.05). In contrast, there were no statistically significant differences between time to maximum block and 25% recovery of twitch height of the thumb as measured by accelography compared to the values measured for the great toe using electromyography during either anaesthetic technique.(ABSTRACT TRUNCATED AT 250 WORDS)