Neuromuscular blockade lnduced by different target effect-site concentrations of rocuronium in female patients

Objective To compare the neuromuscular blockade induced by different target effect-site concentrations (Ces) of rocuronium in female patients.Methods One hundred and twenty ASA Ⅰ or Ⅱ female patients,aged 40-55 yr,with body mass index 18-22 kg/m2,scheduled for elective thyroid or breast surgery under general anesthesia,were included in the study.Anesthesia was induced with midazolam 0.1 mg/kg and fentanyl 5 μg/kg.Target-controlled infusion of rocuronium was started to facilitate tracheal intubation as soon as the patients lost consciousness.The patients were randomly divided into 4 groups ( n =30 each):A,B,C and D groups.In groups A,B,and C,the target Ce of rocuronium was set at 3.5 μg/ml during induction of anesthesia and at 1.0,1.2 and 1.4 μg/ml respectively during maintenance of anesthesia.In group D,the target Ce of rocuronium was set at 3.8 μg/ml during induction of anesthesia and at 1.2 μg/ml during maintenance of anesthesia.The onset time (time from the beginning of target-controlled infusion of rocuronium to T1 =5％ of the control twitch),recovery time (when T1 retumed to 25 ％ of the control twitch),recovery index (the time for Tt to return from 25 ％ to 75 ％of the control twitch),and the total amount of rocuronium consumed during operation were recorded.The intubation conditions and degree of muscle relaxation during operation were assessed.Results Neuromuscular block during operation was significantly better and the rate of satisfactory neuromuscular block was significantly higher in groups B,C and D than in group A ( P ＜ 0.05).Onset time was significantly shorter in group D than in groups A,B and C ( P ＜ 0.05).Compared with group C,the total amount of rocuronium consumed during operation,recovery time and recovery index were significantly decreased in groups A,B and D ( P ＜ 0.05).There was no significant difference in the total amount of rocuronium consumed during operation,recovery time and recovery index between groups B and D (P ＞0.05).Conclusion Rocuronium with the target Ce set at 3.8 and 1.2 μg/ml during induction of anesthesia and mainterance of anesthesia respectively can provide satisfactory neuromuscular block,is helpful to the recovery of neuromuscular block and is more suitable for female patients. Key words: Androstanols; Drug delivery systems; Sex factors