Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA.
Reg Anesth Pain Med. 2012 Jul-Aug;37(4):383-92. doi: 10.1097/AAP.0b013e3182576647.
Peripheral nerve stimulation has a long history in regional anesthesia. Despite the advent of ultrasound-guided peripheral nerve blockade, nerve stimulation remains a popular technique used alone or, now, in combination with ultrasound-guided techniques. In light of this evolving utility of nerve stimulation, this is an appropriate time to review the basic concepts and knowledge base of this historically important tool. Electrical nerve stimulation facilitates nerve localization, using threshold current as a surrogate for needle-to-nerve distance. Preferential activation of motor nerves is possible because motor nerve fibers are more readily activated with a shorter duration of current compared with sensory nerves. The association between current and needle-to-nerve distance predicts that less current is needed to evoke a motor response as the needle moves closer to the nerve. Thus, an elicited motor response at or below 0.5 mA is considered a common end point for successful neural blockade. However, current magnitude is neither 100% sensitive nor specific. Independent of technical ability, both the biological environment and the equipment used impact the current-distance relationship. Thus, successful electrical nerve stimulation is dependent on an anesthesiologist with a solid foundation in anatomy and a thorough understanding of electrophysiology.
周围神经刺激在区域麻醉中有悠久的历史。尽管超声引导下的周围神经阻滞已经问世，但神经刺激仍然是一种单独使用或现在与超声引导技术联合使用的流行技术。鉴于神经刺激的这种不断发展的用途，现在正是回顾这个历史上重要工具的基本概念和知识库的适当时机。电神经刺激有助于神经定位，使用阈值电流作为针到神经距离的替代物。由于与感觉神经相比，运动神经纤维在较短的电流持续时间内更容易被激活，因此可以优先激活运动神经。电流与针到神经距离之间的关联表明，随着针靠近神经，需要的电流越少就能引起运动反应。因此，在 0.5mA 或以下引出的运动反应被认为是成功神经阻滞的常见终点。然而，电流幅度既不是 100%敏感也不是特异性的。无论技术能力如何，生物环境和使用的设备都会影响电流-距离关系。因此，成功的电神经刺激依赖于具有坚实解剖学基础和对电生理学有透彻理解的麻醉师。
