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 fentany l, rapacuronium 1.5 mg/kg was administered to facilitate tracheal intubatio n. Patients were randomized to receive either a propofol infusion (100 mu g .kg(-1).min(-1)) or sevoflurane (1.0%, end-tidal) in combination with nitro us oxide 66% for maintenance of anesthesia. Neuromuscular block was monitor ed 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. Th e clinical duration of action (i.e., time to 25% T-1 recovery) was similar during both propofol (13.1 +/- 3.6 min) and sevoflurane (13.7 +/- 4.4 min) anesthesia. The time from 25% T-1 recovery to TOF ratio of 0.8 was also sim ilar 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 t han 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. Howe ver, more prolonged recovery may occur in the presence of sevoflurane. Impl ications: We studied the reversal of rapacuronium-induced block with edroph onium and found that the residual rapacuronium block can be readily antagon ized during propofol-based anesthesia. However, reversal of rapacuronium ap pears to be less predictable during sevoflurane-based anesthesia.