Rapacuronium recovery characteristics and infusion requirements during inhalation versus propofol-based anaesthesia

We examined the effect of four maintenance anaesthetics on the neuromuscula r blocking activity and spontaneous recovery characteristics after a short- term infusion of rapacuronium. Eighty ASA I-III adult patients undergoing e lective surgery were studied at four centres. Anaesthesia was induced with propofol 1.5-2.5 mg kg(-1) and fentanyl 1-2 mu g kg(-1), followed by a bolu s of rapacuronium 1.5 mg kg(-1). The patients were randomized to receive ei ther desflurane (2-4% end-tidal, ET), sevoflurane (0.75-1.5% ET), isofluran e (0.4-0.8% ET), or a propofol infusion (75-150 mu g kg(-1) min(-1)) for ma intenance of anaesthesia in combination with nitrous oxide (60-70%) in oxyg en. When the first twitch CTI) of a train-of-four stimulus (using the TOF G uard(R) accelerometer) returned to 5%, an infusion of rapacuronium was star ted at 3 mg kg(-1) h(-1) and adjusted to maintain T-1/T-0 at 10%. The durat ion of infusion lasted between 45 and 60 min, and the average infusion rate s of rapacuronium were similar in all groups, ranging from 1.6 to 2.5 mg kg (-1) h(-1). There were no significant differences among the groups in the t imes for T-1/T-0 to return to 25%, 75% or 90%, or for T-4/T-1 to return to 70% and 80% upon discontinuation of the infusion. When potent inhalation an aesthetics are used in clinically relevant concentrations for maintenance o f anaesthesia, the neuromuscular recovery profile of rapacuronium administe red as a variable-rate infusion for up to 1 h is similar to that found with a propofol-based anaesthetic technique.