ABSTRACT
Objective To investigate the effect of rocuronium 0.3 mg/kg(ED95)for anesthesia induclion on monitoring of recurrent laryngeal nerve in patients undergoing thyroid surgery.Methods Seventy-five patients,ASA Ⅰ or Ⅱ,aged 20-70 yr,weighing 50-85 kg,scheduled for thyroid surgery,were randomly divided into two groups:rocuronium group(groupⅠ,n=38)and sevoflurane group(group Ⅱ,n =37).Anesthesia was induced with midazolam 2 mg,propofol 2 mg/kg,sulfentanil 0.5 ug/kg.After loss of eyelash reflex,group Ⅰ received rocuronium 0.3 mg/kg(ED95)and was intubated with the electromyographic(EMG)endotracheal tube under glidescope al 2 min after rocuronium administration.Group Ⅱ received sevoflurane inhalation and was endotracheal intubated with EMG tube until end-tidal sevoflurane concentration achieved 4％.Anesthesia was maintained with inhalation of sevoflurane in both groups.SP,DP,and HR were monitored continuously through the surgery.Cooper's score and the success of attempt at endotracheal intubation were recorded.Recurrent laryngeal nerve evoked EMG was recorded by neuromonitoring and the amplitude of EMG responses was recorded at 5 min intervals from 30 min to 70 min of surgery duration.Results SP,DP and HR remained within normal range in both groups.The success rates of endotracheal intubation were 100％ in both groups,but the Cooper' s score of group Ⅰ was significantly higher than that of group Ⅱ(P ＜ 0.05).Compared with group Ⅱ,the amplitude of EMG respouses was significantly decreased in group Ⅰ(P ＜ 0.05).However,the EMG response in group Ⅰ was adequate for neuromonitoring of recurrent laryngeal nerve.Conclusion Rocuronium 0.3 mg/kg(ED95)for anesthesia induction can not only provide satisfied endotracheal intubation conditions,but also be adequate for monitoring of recurrent laryngeal nerve in patients undergoing thyroid surgery.
ABSTRACT
Objective To compare the density of acetylcholine receptor (AchR) in orbicular muscle of mouth and gastrocnemius muscle and their affmity with rocuronium, trying to elucidate the mechanism for the difference in the sensitivity of the muscles innervated by facial and peripheral nerve respectively to muscle relaxant.Methods Eight pathogen-free adult male SD rats weighing 180-220 g were used in this study. Muscle strips were isolated from orbicular muscle of mouth and gastrocnemius muscle. Each muscle strip was further divided into 6 smaller and slender strips of same size using dissection microscope. One strip was stained with acetylcholinesterase to measure end-plate surface area (ESA). The other 5 strips were exposed to different concentrations of rocuronium (0, 2.5, 5.0, 7.5, 10.0μg/ml). The mean density of AchR at end-plate was obtained by AchR0/ESA. (AchR0 was defined as the number of AchR per end-plate without being exposed to rocuronium. AchRE was defined as the number of free AchR per end-plate after being exposed to different concentrations of rocuronium. ) The degree of saturation of AchR with different concentrations of rocuronium at each neuromuscular junction was calculated by (AchR0 - AchRE)/AchR0 which reflects the affinity of AchR with the rocuronium in orbicular muscle of mouth and gastrocnemius muscle. Results The density of AchR was significantly lower while the affinity with rocuronium was higher in gastrocnemius muscle than in orbicular muscle of mouth ( P ＜ 0.05). Conclusion The density of AchR is lower and the affinity of AchR at end-plate with rocuronium is significantly greater in gastrocnemius muscle innervated by sciatic nerve than in orbicular muscle of mouth innervated by facial nerve. This may explain the mechanism for different sensitivity of the muscles innervated by facial and peripheral nerves to rocuronium.