Duration and recovery profile of cisatracurium after succinylcholine during propofol or isoflurane anesthesia

Study Objective: To determine the duration and recovery profile of maintenance doses of cisatracurium besylate following succinylcholine, and during propofol or isoflurane anesthesia.

Design: Randomized, open-label study.

Setting: Operating suite of a university-affiliated medical center.

Patients: Forty ASA physical status I and II adult patients having elective surgery with general anesthesia lasting longer than 90 minutes.

Interventions: Following a standardized induction sequence, a baseline electromyogram (EMG) was obtained. An intubating dose of intravenous (IV) succinylcholine 1.0 mg/kg was administered. Ventilation was maintained with a face mask until the first twitch (T₁) of the evoked train-of-four (TOF) reached 10% of control when tracheal intubation was performed. Spontaneous recovery from neuromuscular blockade was allowed to occur until the first twitch returned to 25% of control. Patients then were randomized to receive cisatracurium as follows. Group 1: 0.025 mg/kg 0.5 × 95% effective dose (ED₉₅)]; Group 2: 0.05 mg/kg (ED₉₅); Group 3: 0.05 mg/kg (ED₉₅); and Group 4: 0.1 mg/kg (2×ED₉₅). Anesthesia for Groups 1 and 2 were maintained with isoflurane 1% to 2%, 66% nitrous oxide (N₂O) in oxygen (O₂), and in Groups 3 and 4, anesthesia was maintained with propofol 80 to 160 μg/kg/min, 66% N₂O in O₂. The TOF-evoked EMG was recorded at 10-second intervals. The time for the evoked EMG to spontaneously return to 25%, 50%, and 75% of the original baseline was recorded.

Measurements and Main Results: There were 10 patients in each of the four groups. The duration of action of cisatracurium 0.05 mg/kg (ED₉₅) after an intubating dose of succinylcholine is 24.5 ± 10 minutes and 21.3 ± 9 minutes during anesthesia maintained with isoflurane and propofol, respectively. Doubling the dose of cisatracurium resulted in approximately twice the duration of action (40.2 ± 7 min) during propofol anesthesia. Following a dose of cisatracurium 0.025 mg/kg (0.5×ED₉₅), the T₁ of the EMG-evoked response did not decrease below 25% in 7 of 10 patients.

Conclusion: Following succinylcholine, the duration of action of a single dose of cisatracurium 0.05 mg/kg is 20 to 25 minutes during anesthesia maintained with propofol or isoflurane. The duration and recovery profile of cisatracurium is dose dependent during propofol and isoflurane anesthetics. Cisatracurium 0.025 mg/kg is an inadequate maintenance dose following recovery from succinylcholine and it fails to provide adequate surgical relaxation.