Tsuda Kazumasa, Shiiya Norihiko, Takahashi Daisuke, Ohkura Kazuhiro, Yamashita Katsushi, Kando Yumi
First Department of Surgery, Hamamatsu University School of Medicine, Hamamatsu, Japan.
First Department of Surgery, Hamamatsu University School of Medicine, Hamamatsu, Japan
Eur J Cardiothorac Surg. 2015 Aug;48(2):245-51. doi: 10.1093/ejcts/ezu496. Epub 2014 Dec 18.
Specificity of transcranial motor-evoked potentials (MEPs) is low because amplitude fluctuation is common, which seems due to several technical and fundamental reasons including difficulty in electrodes positioning and fixation for transcranial stimulation and susceptibility to anaesthesia. This study aimed to investigate the feasibility, safety and stability of our novel technique of transoesophageal spinal cord stimulation to improve the stability of MEPs.
Ten anaesthetized adult beagle dogs were used. Transoesophageal stimulation was performed between the oesophageal luminal surface electrode (cathode) and a subcutaneous needle electrode (anode) at the fourth to fifth thoracic vertebra level. Stimulation was achieved with a train of five pulses delivered at 2.0-ms intervals. Compound muscle action potentials were recorded from four limbs and external anal sphincter muscles. Stability to anaesthetic agents was tested at varying speeds of propofol and remifentanil, and effects of varying concentration of sevoflurane inhalation were also evaluated.
Transoesophageal MEPs could be recorded without difficulty in all dogs. Fluoroscopic evaluation showed that electrodes misalignment up to 5 cm cranially or caudally could be tolerated. Stimulus intensity to achieve maximum amplitude of hindlimb muscle potentials on both sides was significantly lower by transoesophageal stimulation than by transcranial stimulation (383 ± 41 vs 533 ± 121 V, P = 0.02) and had less interindividual variability. Latency of transoesophageal MEPs was shorter than that of transcranial MEPs at every recording point. No arrhythmia was provoked during stimulation. Animals that were allowed to recover showed no neurological abnormality. In the two sacrificed animals, the explanted oesophagus showed no mucosal injury. Stability to varying dose of anaesthetic agents was similar between transoesophageal and transcranial stimulation, except for the potentials of forelimbs by transoesophageal stimulation that were resistant to anaesthetic depression.
Transoesophageal stimulation for MEPs monitoring was feasible without difficulty and safe. Although its stability to anaesthetic agents was similar to that of transcranial stimulation, its technical ease and small interindividual variability warrants further studies on the response to spinal cord ischaemia.
经颅运动诱发电位（MEP）的特异性较低，因为幅度波动很常见，这似乎是由多种技术和基本原因导致的，包括经颅刺激时电极定位和固定困难以及对麻醉的敏感性。本研究旨在探讨我们新型的经食管脊髓刺激技术提高MEP稳定性的可行性、安全性和稳定性。
使用10只麻醉的成年比格犬。在第四至第五胸椎水平的食管腔表面电极（阴极）和皮下针电极（阳极）之间进行经食管刺激。以2.0毫秒的间隔发送一串五个脉冲来实现刺激。从四肢和肛门外括约肌记录复合肌肉动作电位。在不同速度的丙泊酚和瑞芬太尼下测试对麻醉剂的稳定性，并评估不同浓度七氟醚吸入的影响。
所有犬均能顺利记录到经食管MEP。透视评估表明，向上或向下5厘米的电极错位是可以耐受的。经食管刺激达到双侧后肢肌肉电位最大幅度的刺激强度明显低于经颅刺激（383±41对533±121伏，P = 0.02），且个体间变异性较小。在每个记录点，经食管MEP的潜伏期均短于经颅MEP。刺激过程中未诱发心律失常。恢复的动物未显示神经异常。在两只处死的动物中，取出的食管未显示粘膜损伤。除经食管刺激的前肢电位对麻醉抑制有抗性外，经食管和经颅刺激对不同剂量麻醉剂的稳定性相似。
经食管刺激用于MEP监测可行且安全。尽管其对麻醉剂的稳定性与经颅刺激相似，但其技术简便性和较小的个体间变异性值得进一步研究其对脊髓缺血的反应。
