Paul Bigeleisen
Steve Orebaugh
Patient Position: Supine, head turned as far as is comfortable to the contralateral side, ipsilateral arm adducted.
Indications: Arm, elbow, forearm, or hand surgery.
Needle Size: 22-gauge, 50-mm insulated block needle.
Volume of Local Anesthetic: 20 to 30 mL.
Ultrasonographic Landmarks: The subclavian artery is situated on top of the first rib. The plexus lies posterosuperior to the subclavian artery. The anterior scalene muscle is found anterior to the brachial plexus and subclavian artery. The subclavian vein lies anterior to the anterior scalene muscle. The pleura is immediately deep to the first rib (Fig. 34-1). The plexus at this level appears to be a “cluster of grapes,” made up of small fascicles. The superior, middle, and inferior trunks may be contained in separate fascial compartments or lie within a single epineurial compartment.
Transducer Position: Sagittal oblique in the supraclavicular fossa.
Approach and Technique: Sterile skin preparation, followed by application of a sterile probe cover or sterilization of the transducer. Sterile sonographic gel should be placed on the skin. After the optimum probe position is obtained, local anesthetic is injected subcutaneously at the anterior margin of the transducer. The block needle is inserted in-plane (along the long axis of the transducer), aiming toward the brachial plexus as imaged on the ultrasound unit screen. Whenever possible, the needle tip should be placed immediately superior to the first rib between the rib and the inferior trunk. This will ensure that the inferior trunk is well anesthetized. The peripheral nerve stimulator should be switched on at 0.4 to 1 mA to confirm the needle is in close proximity to the plexus. When motor stimulation of the upper extremity is obtained, or sensory paresthesia of the shoulder, arm, forearm, or hand is sensed by the patient, the stimulator can be switched off. At this point, local anesthetic is injected in small increments below the inferior trunk, with attention to avoiding pain or paresthesias, and the syringe is aspirated for intravascular position. The needle should then be repositioned to ensure that local anesthesia is injected around the middle and superior trunks. Distension of the tissues by local anesthetic, as evidenced on the ultrasound unit screen, should occur with each injection, as confirmation that the needle tip is not intravascular.
|
|
|
Figure 34-1. a, subclavian artery; c, clavicle; IT, inferior trunk; L, lung; MT, middle trunk; omo, omohyoid muscle; r, first rib; ST, superior trunk; v, subclavian vein. |
Tips
1. The needle tip must be kept in full view to avoid inadvertent insertion beyond the first rib, possibly causing a pneumothorax.
2. The in-plane approach can also be carried out from the posterior margin of the transducer. The same safety precautions apply.
3. Before inserting the needle through the skin, depress the tip against the skin and indent it, looking for this motion on the ultrasound screen. This confirms the orientation of needle and probe.
4. Unlike the situation at the level of interscalene block, the entire plexus is compactly arranged at this level. Thus, stimulation may result in motor (or sensory) excitement at any portion of the upper extremity.
5. Use of a tourniquet or surgery on the medial aspect of the arm may necessitate a separate block of the intercostobrachial nerve in the axilla.
Suggested Readings
Chan VWS, Perlas A, Rawson R, et al. Ultrasound-guided supraclavicular brachial plexus block. Anesth Analg 2003;97:1514–1517.
Gruber H, Kovacs P. Sonographic anatomy of the peripheral nervous system. In: Peer S, Bodner G, eds. High resolution sonography of the peripheral nervous system. Berlin: Springer-Verlag, 2003:13–36.
Perlas A, Chan VWS, Simons M. Brachial plexus examination and localization using ultrasound and electrical stimulation. Anesthesiology 2003;99:429–435.
Williams S, Chouinard P, Arcand G, et al. Ultrasound guidance speeds execution and improves the quality of supraclavicular block. Anesth Analg 2003;97:1518–1523.
