Difference in time-course of relaxant effect of rocuronium between patients with ocular and generalized myasthenia gravis / 中华麻醉学杂志

ABSTRACT

Objective To compare the time-course of relaxant effect of rocuronium between patients with ocular and generalized myasthenia gravis (MG).Methods Twenty-seven ASA physical status I or Ⅱ patients with MG of both sexes,aged 12-64 yr,with body mass index of 17-26 kg/m2,scheduled for elective extended thymectomy,were divided into 2 groups according to Osserman stageocular group (group O,n =10) and generalized group (group G,n =17).Anesthesia was induced with iv injection of fentanyl 2 μg/kg,midazolam 0.05 mg/kg,and propofol 1.5 mg/kg.All patients were tracheal intubated and mechanically ventilated.Anesthesia was maintained with iv infusion of propofol 4-8 mg· kg-1 · h-1 and remifentanil 0.2 μg· kg-1 · min-1.Twitch tension was monitored in the adductor pollicis muscle by train-of-four stimulation of the ulnar nerve (intensity 60 mA,interval 12 s,frequency 2 Hz,wave length 0.2 ms).Rocuronium 0.6 mg/kg was injected intravenously after calibration.Mean arterial pressure (MAP),HR,heart rate variability (HRV) and low frequency and high frequency (LF/HF) ratio was recorded.The onset time of muscle relaxation,time for T1 to recover to 25％,time for T1 to recover to 50％ and recovery index were recorded.Results Compared with the baseline value,there were no significant changes in MAP,HR,HRV,LF/HF ratio at all time points in the two groups (P ＞ 0.05).Compared with group O,there was no significant change in the onset time of muscle relaxation,and the time for T1 to recover to 25％,time for T1 to recover to 50％ and recovery index were significantly prolonged in group G (P ＜ 0.05).Conclusion The duration of rocuronium-induced neuromuscular block is significantly longer in patients with generalized MG than those with ocular MG,while the onset time is comparable between the two groups.