神经肌肉阻滞程度对上肢运动诱发电位的影响

Influence of neuromuscular blockade on motor evoked potential of forearm muscles

目的探讨不同神经肌肉阻滞程度对上肢前臂运动诱发电位（MEP）的影响。方法随机选择40例自2007年1—3月期间于华山医院择期行神经外科手术的ASAⅠ～Ⅱ级患者，全麻诱导后均给予丙泊酚＋芬太尼＋维库溴铵全凭静脉麻醉，术中维持脑电双频指数（BIS）值于50±10，芬太尼以2μg·kg^-1·h^-1持续静脉输注，肌松维持用维库溴铵静脉持续输注并行TOF监测，分别于TOF4（TOF=4）、TOF2（TOF=2）及TOF0（TOF=0）时，监测上肢前臂各肌群的MEP，记录并比较潜伏期和波幅的变化。结果随着肌松程度的不断增加，MEP的波幅显著减小（P〈0．05），潜伏期在TOF2较TOF4差异无统计学意义（P〉0．05），而TOF0绝大部分患者已无法记录到MEP波形（P〈0．01）。结论神经肌肉阻滞剂能明显抑制MEP的产生，且呈显著的剂量依赖性。

Objective To investigate the influence of different degrees of neuromuscular blockade on motor evoked potential （MEP） of forearm muscles under the same condition of anesthesia depth and analgesia. Methods Forty ASA Ⅰ - Ⅱpatients aged 20 - 60 underwent general anesthesia via intravenous injection of propofol, fentanyl, and vecuronium to achieve the bispectral index （BIS） at the level of （50 ＋ 10） during neurosurgical operation. The patients were all given fentanyl infusion at a rate of 2 μg/kg/h during the operation and continuous vecuronium injection while the value of train of four stimulations （TOF） was monitored under 3 different levels ： TOF = 4 （ TOF4 ）, TOF = 2 （ TOF2 ）, and TOF = 0 （ TOF0 ）. The values of amplitude and latency at the 3 forearm muscles, forearm flexors （FF） , abductor pollicis brevis （APB）, and abductor digiti minimi （ADM） were monitored and compared under stable hemodynamic status. Results There was no significant differences in the latency of compound muscle action potential （CMAP） between the anesthesia status TOF4 and anesthesia status TOF2 in FF, APB, and ADM （ all P 〉 0. 05 ）. The amplitude of CMAP deceased gradually as the degree of neuromuscular blockade increased in FF,APB, and ADM （all P 〈0.05）. CMAP could not be recorded when the value of TOF was 0 （ P 〈 0. 01 ）. Conclusion Neuromuscular blocking drugs significantly depress the MEP in a dose-dependent manner, lntra-operatively it may be preferable to maintain the value of TOF not less than 2 during the critical periods of MEP monitoring.