三种诱发电位术中监测脊髓功能的实际应用价值

背景:诱发电位监测脊髓功能预防神经损伤的作用及技术已广泛应用,出现的问题亦逐渐增多。目的:观察常用麻醉药物及控制性降血压对猴皮层体感诱发电位(CSEP)、脊髓体感诱发电位(SSEP)和经颅磁刺激运动诱发电位(MEP)的影响,评价诱发电位术中监测的作用及影响因素。设计:前后对照研究。单位:中山大学孙逸仙纪念医院骨科、麻醉科。对象:实验在中山大学孙逸仙纪念医院林百欣医学研究中心完成。10只健康猕猴(广州动物园购入),雌雄不限,体质量3.8～5.8kg,平均4.3kg。干预:测量10只健康猕猴CSEP,SSEP和MEP并保留基线用于对比。将猴模拟脊柱手术中的麻醉及控制性降压等操作,然后分别给异丙酚(2mg/kg)、芬太尼(4μg/kg)、氯胺酮(6mg/kg)、硝普钠和异氟醚犤1.5最低肺泡有效浓度(MAC)犦等,每次给药后观察CSEP,SSEP和MEP变化,最后控制性降血压,观察图形改变。主要观察指标:给药后猴CSEP,SSEP和MEP变化。结果:氯胺酮对皮层CSEP的潜伏期影响最明显,可延长3～5ms;异氟醚对皮层CSEP的波幅影响最大,可降低50%～100%;控制性降压中,波形亦随之变化。SSEP几乎不受其他因素影响。结论:单独使用CSEP监测必须与麻醉密切配合,否则既不稳定又不可靠,SSEP是最佳监测方法。

Practical value of three techniques of evoked potentials in monitoring spinal cord function during operation

BACKGROUND: The techniques of evoked potentials have been generally applied in monitoring spinal cord function, but many problems have appeared with the use of the techniques.OBJECTIVE: To observe the influence of anesthetic drugs and the controlled hypotension on cortical somatosensory evoked potential(CSEP),spinal somatosensory evoked potential(SSEP) and motor evoked potential (MEP) during the operation, and investigate their effect and influencing factors on those evoked potential.DESIGN: A controlled pre- and post-comparison study.SETTING: Department of Orthopaedics and Department of Anesthesiology,Sun Yat-sen Memorial Hospital, Sun Yat-sen University of Medical Sciences.PARTICIPANTS: The experiment was conducted in Lin-bai-xin Medical Research Center, Sun Yat-sen Memorial Hospital, Sun Yat-sen University of Medical Sciences. Ten healthy macaques bought from Guangzhou Zoo, in either gender, with a mean body mass of 4. 3 kg(3.8 -5.8 kg) were selected in the experiment, and anesthetized to mimic the procedures of spinal surgery monitored by CSEP, SSEP and MEP.INTERVENTION: The CSEP, SSEP, MEP of the 10 macaques were measured and baseline was retained for contrast. The procedures of spinal surgery, anesthesia and controlled hypotension were performed in the animals. Propofol(2mg/kg), fentanyl(4μg/kg), Ketamine(6mg/kg), nitroprusside-Na and isoflurane1.5 minimum alveolar concentration(MAC)]were applied in turn, after the wave go back to standard, the change of CSEP, SSEP, MEP of each administration were observed. Eventually controlled hypotension was applied to observe the change of figure.MAIN OUTCOME MEASURES: Changes of CSEP, SSEP and MEP after administration.RESULTS: The influence of ketamine on CSEP latency phase was the most significant, its latency was increased by 3- 5 ms, while the influence of isoflurane on wave amplitude was the most significant, it were decreased by 50% - 100%. Waveform were also changed with controlled hypotension, but the SSEP was hardly affected by anesthetic agents and other managements.CONCLUSION: The use of CSEP alone is neither stable nor reliable and it should be closely connected with anesthetic, the SSEP is the best method to monitor the spinal cord function.