Helen L, O'Donnell B D, Moore E
Sensing and Separation Group, Chemistry Department and Life Science Interface Group, Tyndall National Institute, University College Cork, Cork, Ireland.
Department of Anesthesia, Cork University Hospital & ASSERT for Health Centre, University College Cork, Cork, Ireland.
Acta Anaesthesiol Scand. 2015 Sep;59(8):962-74. doi: 10.1111/aas.12544. Epub 2015 May 22.
Ultrasound guidance is now a standard nerve localization technique for peripheral nerve block (PNB). Ultrasonography allows simultaneous visualization of the target nerve, needle, local anesthetic injectate, and surrounding anatomical structures. Accurate deposition of local anesthetic next to the nerve is essential to the success of the nerve block procedure. Due to limitations in the visibility of both needle tip and nerve surface, the precise relationship between needle tip and target nerve is unknown at the moment of injection. Importantly, nerve injury may result both from an inappropriately placed needle tip and inappropriately placed local anesthetic. The relationship between the block needle tip and target nerve is of paramount importance to the safe conduct of peripheral nerve block.
This review summarizes the evolution of nerve localization in regional anesthesia, characterizes a problem faced by clinicians in performing ultrasound-guided nerve block, and explores the potential technological solutions to this problem.
To date, technology newly applied to PNB includes real-time 3D imaging, multi-planar magnetic needle guidance, and in-line injection pressure monitoring. This review postulates that optical reflectance spectroscopy and bioimpedance may allow for accurate identification of the relationship between needle tip and target nerve, currently a high priority deficit in PNB techniques.
Until it is known how best to define the relationship between needle and nerve at the moment of injection, some common sense principles are suggested.
超声引导现已成为外周神经阻滞（PNB）的标准神经定位技术。超声检查可同时显示目标神经、穿刺针、局部麻醉剂注射液及周围解剖结构。将局部麻醉剂准确注射到神经旁是神经阻滞操作成功的关键。由于针尖和神经表面的可视性存在局限性，在注射时，针尖与目标神经之间的精确关系尚不清楚。重要的是，针尖位置不当和局部麻醉剂注射位置不当都可能导致神经损伤。阻滞针针尖与目标神经之间的关系对于安全实施外周神经阻滞至关重要。
本综述总结了区域麻醉中神经定位的发展历程，描述了临床医生在进行超声引导神经阻滞时面临的问题，并探讨了针对该问题的潜在技术解决方案。
迄今为止，新应用于PNB的技术包括实时三维成像、多平面磁针引导和在线注射压力监测。本综述推测，光学反射光谱法和生物阻抗技术可能有助于准确识别针尖与目标神经之间的关系，而这正是目前PNB技术中亟待解决的一个重要问题。
在明确如何在注射时最佳地确定针与神经之间的关系之前，建议遵循一些常识性原则。
