接上篇：临床脑电图操作的最低技术要求之设备

2 电极

2.1 记录电极应注意避免噪音和移动。它们对0.5 ~ 70Hz间的信号不会产生明显衰减作用。实验证明火棉胶粘银-氯化银或金质盘状电极是最佳选择（编者注：标准发布时间为2006年，技术有进步，粉末银/氯化银电极粘医用导电膏是目前最佳选择)，但若是联用一些具有高输入阻抗的增益装置，就可以由更多的有效的电极材料和电极粘附物可以选择。（一些制造商制造的高质量电极往往比资质的电极更为好用。减少噪音，保持电极的清洁，以及为由传染性疾病（病毒性肝炎、朊蛋白病、获得性免疫缺陷综合征）的患者进行记录后做好恰当的防护措施。

2.2 针电极是不推荐使用的，若环境所需不得不使用时，必须做好消毒工作或用完后直接抛弃。使用针电极的技术工作者应掌握好针电极的确切使用技术，并熟知使用针电极的缺点和危险性，校正针电极以保持前后平衡是重要的。若是针电极校正不到位，可能会引起波幅不一致或扭曲。使用针电极与实用其他任何形式的电极比，需要更多的专业知识和细心，但这一点往往很少引起大家的重视。然而，针电极可以更有效的用于昏迷的患者，后者对于痛觉的反应欠灵敏。同时针电极具有的最小时间延迟特性也能更有效的记录病人的脑电信号。

3.3 国际临床电生理学会（IFCN）所推荐的21个电极安放点都可以使用。10-20系统是IFCN唯一官方推荐系统，也是目前最常用的系统。“修订版10-20系统”是不合适的，因为它允许在不进行头部测量的情况就安置电极的位置，这样往往会产生误导的结果，称其为“估计10-20系统放置法”更为恰当。“10-10”系统应该适用于指南5所述的扩展组合系统中。足够数量的电极对于确保脑电活动的测量是非常重要的，只有用足够的点，才能记录到头皮最小代表区的电活动，这样更有利于准确分析复杂电活动的分布情况。在某些特殊情况下少量电极更为合适，但这种情况较少有。有时为了记录一些非常局限部位的电活动，我们会在标准电极放置部位的附近加放一些额外电极。除非像手术室这种地方，患者全身连有其他电子设备时可以不用接电电极，其他情况下往往需要使用接地电极。使用重复接地是不允许的，连载患者身上的接地电极必须只能直接连接在总的接地线上而不能间接连在其他任何设备的接地线上。

2.4 每次进行检查前都需要检测电极间的阻抗，一般情况下，电极间阻抗应控制在5000欧姆（5KΩ）内。如果有任何图形出现伪迹，就必须在记录中重新检查电极间的阻抗。

英文原文

2. Electrodes

2.1 Recording electrodes should be free of inherent noise and drift. They should not significantly attenuate signals between 0.5 and 70 Hz. Experimental evidence suggests that silver—silver chloride or gold disk electrodes held on by collodion are the best, but other electrode materials and electrode pastes have been effectively used especially with contemporary amplifiers having high input impedances. High-quality electrodes are available from several manufacturers and are generally preferable to homemade electrodes.

To decrease noise, electrodes must be kept clean, with appropriate precautions taken after recording from patients with contagious diseases (viral hepatitis, Creutzfeldt-Jakob disease, acquired immunodeficiency syndrome.) (AEEGS, 1994; ASET, 2000)

2.2 Needle electrodes are not recommended. If circumstances necessitate their use, they must be completely sterilized or discarded after use, and the technologist who em-ploys them should have been taught the exact techniques, as well as the disadvantages and hazards, of their use. Parallel anteroposterior alignment of the needles is important; misalignment may cause artifactual amplitude asymmetries or distortions.

It is rarely appreciated that proper use of needle electrodes requires more care and expertise than for any other type of electrode. However, needle electrodes can be effectively utilized in comatose patients, in whom pain responses are usually minimal or absent, and who are in medical settings requiring efficient recording with a minimum of delay.

2.3 All 21 electrodes and placements recommended by the International Federation of Clinical Neurophysiology (IFCN; Jasper HH, 1958, 1983) should be used. The 10-20 System is the only one officially recommended by the IFCN. It is the most commonly used existing system, and it should be used universally. The use of the term “modified 10-20 System” is undesirable and misleading when it means that head measurements have not been made and placements have been estimated. In this case, the term “estimated 10-20 placement” is more appropriate. The term “10-10 System” should be used for the extended combinatorial system described in Guideline 5. (For neonates, refer to Guideline 2.)

An adequate number of electrodes is essential to ensure that EEG activity having a small area of representation on the scalp is recorded and to analyze accurately the distribution of more diffuse activity. A smaller number of electrodes may be appropriate for special circumstances, but is not considered comprehensive. Occasionally, additional electrodes, placed between or below those representing the standard placements, are needed in order to record very localized activity.

A grounding electrode always should be used, except in situations (e.g., intensive care units, operating rooms) in which other electrical equipment is attached to the patient. In such cases, double grounding must be avoided. The ground electrode on the patient must be connected only to the appropriate jack of the input jackbox, and never to the equipment chassis or other earth ground.

2.4 Interelectrode impedances should be checked as a routine prerecording procedure. Ordinarily, electrode impedance should not exceed 5000 Ohms (5 KOhms.)

Electrode impedances should be rechecked during the recording when any pattern that might be artifactual appears.

翻译：陈玉娟

编辑：格格