Effect of vecuronium at different doses for induction of anesthesia on monitoring of recurrent laryngeal nerve in patients undergoing thyroid operation

Abstract

Objective To investigate the effect of vecuronium at different doses for induction of anesthesia on monitoring of recurrent laryngeal nerve in patients undergoing thyroid surgery.Methods One hundred and seventeen patients,ASA Ⅰ or Ⅱ,aged 20-64 yr,weighing 50-85 kg,scheduled for thyroid surgery,were randomly divided into three groups:group Ⅰ (n =39),group Ⅱ (n =40) and group Ⅲ(n =38).Anesthesia was induced with midazolam 2 mg,propofol 2 mg/kg,sulfentanil 0.5 μg/kg.Following BIS value at 40-50,vecuronium 0.05(ED95) or 0.10 mg/kg (2 × ED95)was intravenously injected in group Ⅰ or Ⅱ respectively,and the electromyographic (EMG) endotracheal tube was intubated under glidescope at 5 min after vecuronium administration.Group Ⅲ received sevoflurane inhalation and the EMG endotracheal tube was intubated following end-tidal sevoflurane concentration at 4％.Anesthesia was maintained with inhalation of sevoflurane in three groups.Cooper' s score and the success of attempt at endotracheal intubation were recorded.The recurrent laryngeal nerve-evoked EMG response was monitored to record the amplitude at 5 min intervals from 30 min to 70 min following surgery.Results The success rates of endotracheal intubation were 100％ in three groups,but the Cooper' s score of groups Ⅰ and Ⅱ was significantly higher than that of group Ⅲ (P ＜ 0.05),while there was no significant difference between groups Ⅰ and Ⅱ.In spite of the EMG amplitude being significantly decreased as compared with group Ⅲ,the EMG response was adequate for monitoring of recurrent laryngeal nerve in group Ⅰ.The EMG response was lost 30 min following surgery,and inadequate for neuromonitoring of recurrent laryngeal nerve 35-45 min following surgery in group Ⅱ.Conclusion Vecuronium 0.05 mg/kg (ED95)for induction of anesthesia may be helpful to provide satisfactory endotracheal intubation conditions,also not affect the monitoring of recurrent laryngeal nerve in patients undergoing thyroid surgery,which can be recommended as the optimal dosage. Key words: Vecuronium ; Anesthesia, general; Monitoring, physiologic ; Recurrent laryngeal nerve ; Thyroidectomy