1. 旁正中的方法用于胸硬膜外麻醉

Paramedian approach for thoracic epidural anesthesia. This approach may avoid the difficulties inherent in midline needle placement between long and acutely angulated thoracic spinous processes. Furthermore, it may offer an extra degree of control as the needle approaches the narrow thoracic epidural space, at which point the spinal cord is only millimeters beyond the dura. To perform a paramedian approach, the skin is marked 0.5 to 1 cm lateral to a thoracic spinous process. After local anesthetic infiltration, the epidural needle is advanced until the underlying lamina is contacted. The needle is then \lamina and encounter the firm lateral reflection of the ligamentum flavum. The epidural space is subsequently identified by slowly advancing the needle using the loss-of-resistance technique.

2.丧失抵抗的胸硬膜外麻醉

Loss-of-resistance technique. After the epidural needle is seated within the ligamentum flavum, the anesthesiologist notes strong resistance to compression of the syringe barrel. This resistance is best visualized by observing the compression of a small air bubble within the saline-filled syringe. As the epidural needle is advanced through the ligamentum flavum, a sudden loss of resistance occurs as the needle tip exits the tick ligament and enters the epidural space

.悬滴法用于颈硬膜外隙的确定

Hanging drop technique for cervical epidural space identification (A and

.

Because negative pressure exists in the cervical epidural space, the anesthesiologist may use the hanging drop technique for cervical epidural space identification. The epidural needle is placed into the ligamentum flavum; however, instead of attaching a syringe, a drop of water is placed in the epidural needle hub. The drop of water is \needle hub by negative pressure as the needle tip enters the epidural space.

4..通过骶尾膜给针头定位

A needle directed through the sacrococcygeal membrane at a 45o angle will usually enter the ligament with a \needle needs to be rotated so that the bevel does not scrape the periosteum of this layer. The angle of advancement also needs to be changed to allow direct passage 2 to 3 cm up the canal without contacting bone again. This space is generously endowed with blood vessels, and the terminal point of the dural sac extends a variable distance into the sacral canal, but usually lies at the S2 level.

5.脊髓穿刺针位置侧面观

Lateral view of the spinal needle direction. In the classical midline approach, the needle is introduced between the two spinous processes with a slight cephalad angulation. When angled correctly (A), the needle passes through the interspinous ligament and into the ligamentum flavum. When the needle is directed too far inferiorly (

, it contacts the bony

ridge of the inferior spinous process. Cephalad redirection allows the needle to pass further. When angling in the cephalad direction produces contact with the bone at a shallower level (C), the bone contacted is the inferior border of the superior spinous process, and more caudad redirection is needed. By adjusting the angle with each pass based on these observations, the interspace usually can be found. If bone is contacted at the same depth on repeated passes, the most likely explanation is that the needle is not in the midline position but has deviated laterally to contact the lamina. The identity of the true midline should then be reassessed

6.脊髓穿刺针旁正中和侧面的进入

Paramedian and lateral approach of spinal needle insertion. In the classical midline spinal approach, the needle traverses the interspinous ligament and the ligamentum flavum before entering the dura. In patients with extremely calcified interspinous ligaments, the needle can be introduced 1 cm lateral to the midline and angled slightly toward the midline as it is advanced, thus avoiding the interspinous ligament and yet still piercing the ligamentum flavum and dura near the midline. In patients with more advanced osteoarthritis, it is sometimes useful to use a more paramedian approach in which the needle is actually introduced inferior and lateral to the interspace. Skin entry is performed 1 cm lateral to the spinous process, inferior to the space desired to be entered. The needle is advanced perpendicular to the skin until it contacts the lamina of the vertebral body and then walked upward and inward at 45o angles until it approaches the midline in the interspace. These approaches are suitable for both spinal and epidural blockade.