PERIOPERATIVE MONITORING OF NEUROMUSCULAR-TRANSMISSION USING ACCELEROMYOGRAPHY PREVENTS RESIDUAL NEUROMUSCULAR BLOCK FOLLOWING PANCURONIUM

The frequency of postoperative residual neuromuscular block following the use of the long-acting non-depolarizing muscle relaxants is high, and manual evaluation of the response to nerve stimulation does not el iminate the problem. In this prospective and randomized study we evalu ated the hypothesis that perioperative use of acceleromyography would allow for a more rational and precise administration of the long-actin g muscle relaxant pancuronium resulting in a decrease in 1) the incide nce and severity of postoperative residual neuromuscular block, 2) the amount of pancuronium used, and 3) the time from end of surgery to tr acheal extubation. forty adult patients were randomized into two group s, one managed without the use of a nerve stimulator, the other monito red using train-of-four (TOF) nerve stimulation and acceleromyography. All patients were anaesthetized with diazepam, fentanyl, thiopentone, nitrous oxide, and in some patients halothane, and they all received pancuronium 0.08-0.1 mg kg(-1) for tracheal intubation, and 1-2 mg for maintenance of neuromuscular block. Neostigmine 2.5 mg preceded by at ropine 1 mg was administered for reversal. In the patients managed wit hout a nerve stimulator, the trachea was extubated when the anaestheti st judged the neuromuscular function to have recovered adequately for upper airway protection and spontaneous ventilation. In patients monit ored with acceleromyography, the trachea was extubated when the TOF ra tio was above 0.70. In all 40 patients, TOF ratio was measured using m echanomyography immediately after tracheal extubation and the patients were evaluated for clinical signs of residual neuromuscular block. Tr ain-of-four ratios, as measured mechanically, varied between 0.26 and 0.96 (median 0.65) in the group nor monitored during the operation wit h acceleromyography. Seven patients in this group were unable to susta in head lift for 5 seconds and five patients were unable to lift an ar m to the opposite shoulder, as compared to 1 and 0 patients, respectiv ely in the group monitored using acceleromyography (P<0.05). The time from end of surgery to tracheal extubation varied between 0 and 25 min (median 10 min) in the group not monitored as compared to 7-47 min (m edian 15 min) in the monitored group (P<0.01). There was no statistica lly significant difference in the total dose of pancuronium given in t he two groups. It is concluded, that by using acceleromyography during anaesthesia it is possible to avoid the problem of residual neuromusc ular block following pancuronium. However, in this study this happened at the expense of a slightly prolonged recovery time (5 min longer). Under the conditions of the study the use of acceleromyopraphy did not influence the amount of pancuronium used during anaesthesia.