什么叫同轴，目标不变？

This approach is similar to the landmark-guided paratracheal approach except the target is the C7 anterior tubercle or the junction between C7 tubercle and vertebral body (Fig. 29.3). To begin, the patient is placed in the supine position with slight hyperextension of the neck. Using fluoroscopy in posteroanterior (PA) view, square the C7 vertebral body end plates, and identify the C7 tubercle and transverse process. Importantly, at the level of C7, the vertebral artery and vein lie anterior to the stellate ganglion, unlike at the C6 level where the vertebral artery is shielded by the anterior tubercle of C6 (Chassaignac’s tubercle). To avoid the vertebral artery, the target location lies medial to the C7 tubercle between the tubercle and vertebral body junction. Administer subcutaneous local anesthetic, and advance a 22- or 25-gauge spinal needle coaxially until contact with bone is made. Then withdraw the needle approximately 2–4 mm, and confirm depth in the lateral view. After negative aspiration for blood, air, or CSF, inject contrast under real-time fluoroscopy in the PA view, and observe for optimal spread along the anterolateral borders of ~C6–T2 vertebral bodies to ensure adequate blockade of the stellate ganglion. Once proper needle placement is confirmed, cautiously inject 0.5 ml of 1% lidocaine, and monitor for aberrant symptomatic changes. If the test dose produces no adverse events, inject 5–10 mL of 1% lidocaine or 0.25% bupivacaine with or without a steroid in an incremental fashion with frequent aspiration. The use of hand signals to confirm or deny adverse events can be beneficial. This minimizes movement of surrounding the neck muscles that may distort needle placement.

除靶点为C7前结节或C7结节与椎体的连接处，该入路与体表标志引导的气管旁入路相似（图29-3）。首先，患者仰卧位，颈部稍过伸。采用后前位（PA）透视，对准C7椎体终板，并识别C7结节和横突。重点注意：不同于C6水平的椎动脉得到前结节（Chassaignac结节）保护，C7水平的椎动脉和静脉位于星状神经节前方。为了避开椎动脉，靶点位于C7结节与椎体连接处之间的C7结节内侧。皮下局部麻醉，采用22或25号脊麻穿刺针同轴推进，触及骨质后将针退出约2～4mm，在侧位上确认深度。回抽无血液、空气或脑脊液，在PA位实时透视下注射造影剂，观察C6～T2椎体前外侧缘是否为最佳扩散，以确保充分阻滞星状神经节。一旦确定正确的针位，谨慎注射1%利多卡因0.5ml，并监测是否有异常症状。如果试验剂量未引发不良事件，则以在多次回抽无血后，渐进、分次注射1%利多卡因或0.25%布比卡因5～10ml（含或不含类固醇类药物）。使用手势来确定是否不适可能有益，这最大限度地减少了可能导致针尖移位的颈部周围的肌肉活动。

什么叫同轴，目标不变？谢谢