Reversal of rapacuronium block during propofol versus sevoflurane anesthesia

We studied the antagonism of rapacuronium with edrophonium-atropine during propofol- or sevoflurane- based anesthesia in 60 healthy outpatients. After the induction of anesthesia with standardized doses of propofol and fentanyl, rapacuronium 1.5 mg/kg was administered to facilitate tracheal intubation. Patients were randomized to receive either a propofol infusion (100 microg. kg(-1). min(-1)) or sevoflurane (1.0%, end-tidal) in combination with nitrous oxide 66% for maintenance of anesthesia. Neuromuscular block was monitored by using electromyography at the wrist and reversed with edrophonium 1.0 mg/kg and atropine 0.015 mg/kg when the first twitch (T(1)) response of the train-of-four (TOF) stimulation recovered to 25% of the baseline value. The clinical duration of action (i.e., time to 25% T(1) recovery) was similar during both propofol (13.1 +/- 3.6 min) and sevoflu-rane (13.7 +/- 4.4 min) anesthesia. The time from 25% T(1) recovery to TOF ratio of 0.8 was also similar with propofol (3.4 +/- 2.1 min) and sevoflurane (5.9 +/- 8.7 min) (P > 0.05). Although none of the patients in the propofol group required more than 9 min to achieve a TOF ratio of 0. 8, two patients receiving sevoflurane required 31 min and 37 min. Adequate antagonism of rapacuronium block with edrophonium can be achieved within 10 min during propofol anesthesia. However, more prolonged recovery may occur in the presence of sevoflurane. We studied the reversal of rapacuronium-induced block with edrophonium and found that the residual rapacuronium block can be readily antagonized during propofol-based anesthesia. However, reversal of rapacuronium appears to be less predictable during sevoflurane-based anesthesia.