Urmey William F, Grossi Paolo
Regional Anesthesia and Pain Treatment Department, Instituto Policlinico San Donato, Università degli Stidi di Milano, Milan, Italy.
Reg Anesth Pain Med. 2002 May-Jun;27(3):261-7. doi: 10.1053/rapm.2002.31211.
Typically, peripheral nerve block is done by approximating nerve location, usually by use of anatomical landmarks. Precise nerve location has been done by needle exploration. A new method, percutaneous electrode guidance (PEG) of the block needle, was performed. A transcutaneous stimulating cylindrical electrode was used to indent the skin, locate the underlying nerve, and guide a block needle near it.
PEG was used to prelocate the desired nerve or neural plexus by use of a shielded cylindrical electrode with a 1-mm-diameter conductive area of skin contact at the distal end, the center of which contained a 22-gauge (1/2 mm) hole, which precisely matched a shielded conventional block needle. Transcutaneous stimulation began at less than 10 mA and was decreased to minimal amperage that elicited the desired motor response. Electrode position was fixed, and electrode current was discontinued. A shielded 22-gauge block needle was advanced through the electrode guide to near the underlying nerve. Initial needle current was only 0.5 mA. Local anesthetic was injected to block the targeted nerve or nerves. Standard sensory/motor testing was performed at 20 minutes.
Nine upper or lower extremity blocks were performed on 7 patients. All were successful. Minimal stimulating currents were 1.3 to 8.2 mA for transcutaneous electrode stimulation and 0.20 to 0.70 for needle stimulation. Needle depth was 0.4 to 1.1 cm beyond the electrode tip and correlated with minimal electrode stimulating current.
A smooth, metal-tipped electrically shielded skin electrode probe can be used to comfortably and accurately indent the skin over a desired nerve or plexus, define its anatomical course, and subsequently guide a block needle near it.
通常，外周神经阻滞是通过接近神经位置来完成的，一般借助解剖标志。精确的神经定位则通过针探来实现。我们开展了一种新方法，即经皮电极引导（PEG）阻滞针。使用经皮刺激圆柱形电极压陷皮肤，定位其下方的神经，并将阻滞针引导至其附近。
使用PEG通过一个远端带有直径1毫米导电皮肤接触区域的屏蔽圆柱形电极预先定位所需神经或神经丛，该电极中心有一个22号（1/2毫米）的孔，与屏蔽传统阻滞针精确匹配。经皮刺激从小于10毫安开始，逐渐降至引发所需运动反应的最小电流强度。固定电极位置，停止电极电流。将屏蔽22号阻滞针通过电极导向器推进至下方神经附近。初始针电流仅为0.5毫安。注射局部麻醉药以阻滞目标神经。20分钟后进行标准感觉/运动测试。
对7例患者进行了9次上肢或下肢阻滞。均获成功。经皮电极刺激的最小刺激电流为1.3至8.2毫安，针刺激的最小刺激电流为0.20至0.70毫安。针的深度超出电极尖端0.4至1.1厘米，且与最小电极刺激电流相关。
一种光滑、金属尖端的电屏蔽皮肤电极探头可用于舒适且准确地压陷所需神经或神经丛上方的皮肤，确定其解剖走行，并随后将阻滞针引导至其附近。
