Background and objectives: The effects of neuromuscular blockers on the neuromuscular junction are potentiated by volatile anesthetics. This study aimed at evaluating the influence of sevoflurane and isoflurane on the recovery of cisatracurium- induced neuromuscular block.
Methods: Ninety ASA I and II patients undergoing elective surgeries under general anesthesia were included in this study. Patients were allocated in three groups: Group I (sevoflurane), Group II (isoflurane) and Group III (propofol). All patients were premedicated with intramuscular midazolam (0.1 mg.kg-1) 30 min before surgery. Anesthesia was induced with alfentanil (50 microg.kg-1), propofol (2.5 mg.kg-1) and cisatracurium (0.15 mg.kg-1). Patients were then ventilated under mask with 100% O2 until disappearance of all TOF responses when laryngoscopy and tracheal intubation were performed. Volatile agents for anesthetic maintenance were introduced immediately after tracheal intubation in 2% and 1% concentrations, respectively, for sevoflurane and isoflurane, as well as the propofol continuous infusion (7 to 10 mg.kg-1.h-1) for Group III. All patients received a 50% mixture of O2 and N2O. Neuromuscular function was monitored by adductor pollicis muscle acceleromyography with TOF stimulation at 15-second intervals. Clinical duration of neuromuscular block (T1(25%)) and recovery index (RI=T1(25-75%)) were evaluated.
Results: Mean time and standard deviation for clinical duration (T1(25%)) and recovery index (RI=T1(25-75%)) were respectively: Group I (66.2 +/- 13.42 min and 23.6 +/- 5.02 min), Group II (54.4 +/- 6.58 min and 14.9 +/- 3.82 min) and Group III (47.2 +/- 7.43 min and 16.2 +/- 2.93 min). There were significant differences in clinical duration between Groups I and II, I and III and II and III. There was a significant difference in recovery index between Group I and the other groups.
Conclusions: The recovery from cisatracurium-induced neuromuscular block was longer during anesthesia with volatile agents as compared to propofol. The most pronounced effect was observed with sevoflurane.