Atracurium recovery: prediction of safe reversal times with edrophonium

The time to safe return of neuromuscular function after atracurium 0.3 mg/kg intravenously was assessed in 24 patients in whom anaesthesia was maintained with halothane 0.5%. Safe reversal (recovery to a T4 ratio greater than 0.5), after this dose of atracurium, could only be reliably and rapidly (less than 2 minutes) achieved with edrophonium if a period greater than 30 minutes elapsed since administration of the relaxant. This coincides with the appearance of four recognisable twitches if a train-of-four pattern of nerve stimulation is used. Thus, if no monitoring equipment is available, at least half-an-hour should elapse after administration of atracurium in a moderate dose (e.g. 0.3 mg/kg) before rapid and reliable reversal can be anticipated. Four twitches in a train-of-four should be recognisable, if a nerve stimulator is available.