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 (i.v.) 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 x 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 x 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 micrograms/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 isoflurance 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 x 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.