Supraclavicular Block

A supraclavicular block targets the brachial plexus at the level of divisions for upper extremity surgery and primarily covers the axillary, musculocutaneous, and radial nerves with possible delay of median nerve distribution blockade. If this block is performed for shoulder surgery, then the addition of a separate superficial cervical nerve block is needed.

Indication

As primary anesthesia and/or postoperative pain management with or without a continuous catheter for humerus (distal), elbow, forearm, hand, or wrist surgeries.

Technique Preparation

Arrange sterile towels, sterile gloves, gauze pads, marking pen, antiseptic solution, peripheral nerve stimulator, syringes, and needles for local infiltration and nerve block placement.

Dose

20-40 ml syringes of local anesthetic. Needles

25 g 1.5 in. needle for skin infiltration and a 22 g 5 cm short bevel insulated stimulation needle.

Agents

3% chloroprocaine, 2% lidocaine, 0.5% ropivacaine, 0.5% bupivacaine.

Surface Anatomy and Landmarks Landmarks

Landmarks include sternocleidomastoid m., anterior and middle scalene m., clavicle, first rib, and subclavian artery (Fig. 20.4a, b). In the classic approach, the patient is positioned supine or semi-sitting with their head turned away from the side to be blocked. The arms are to remain relaxed at the patient's side. The brachial plexus is approached with the clavicle first identified and the midpoint marked (Fig. 20.4a). Following skin cleansing and local

Figure 20.4 (a) and (b) Landmarks for the supraclavicular approach to the brachial plexus. (a) Line #1 sternal notch and line #2 sternocleidomastoid (SCM) muscle. Line #3 identifies the clavicle. Single medial arrow indicates the lateral portion of the SCM muscle attachment to the clavicle. Parallel arrow (pointing cephalad) is approximately one-thumb width (2.5 cm) lateral to the medial arrow and provides a margin of safety away from the pleura dome. (b) Line #1 sternal notch, line #2 sternocleidomastoid (SCM) muscle, and line #3 the clavicle. Single arrow pointing caudad identified the point on needle entry. This point is located cephalad to the palpating finger positioned above line #3, marking the clavicle. Arrows on each side of the palpating finger identify the direction of the advancing needle that is aligned parallel to the body midline.

infiltration, a 22-gauge 5 cm b-bevel needle is connected to a nerve stimulator set at 1.0 mA (activate nerve stimulator subsequent to subcutaneous needle placement) and inserted one-finger width cephalad to the mid-clavicular point which is 2.5 cm lateral to the SCM muscle attachment of the clavicle (Fig. 20.4b). The needle is then directed caudally after penetrating 2-5 mm perpendicular through the skin. Typically the first rib will be contacted by the needle at a depth of about 2-4 cm; the needle is then "walked off' the first rib until a paresthesia to the arm or thumb is elicited or an appropriate muscle twitch is obtained at a stimulation between 0.2 and 0.5 mA. The appropriate needle response should occur above the clavicle and under the palpating finger. Caution should be used not to direct the needle medially toward the cupola of the lung. After appropriate nerve stimulation, including flexion or extension of the wrist or digits, 20-40 ml of local anesthetic are injected in incremental doses following a negative aspiration for blood. Alternatively, a continuous single orifice catheter may be inserted to provide continuous infusion of local anesthetic.

Pitfalls and Pearls Pitfalls

Several side effects from supraclavicular blockade may occur. Since the cupola of the lung is at the level of a supraclavicular block, one complication that may occur is a pneumothorax (0.5-6% incidence), depending on the experience and skill of the anesthesiologist. This complication must be considered if the patient develops chest pain or cough, even hours after performing a supraclavicular block. There is an increased risk of pneumothorax if the needle is allowed to be directed medially, which may result in contact with the pleura. Therefore, outpatients with severe lung disease may not be appropriate candidates for this block. Blockade of the ulnar nerve distribution may be spared or delayed. Another possible side effect is phrenic nerve or sympathetic chain block with the supraclavicular approach (less common than with an interscalene block). Infection, hematoma, bleeding, nerve injury, and intravascular injection (subclavian vessels are in the region of a supraclavicular approach to the brachial plexus) are also potential problems.

Pearls

The brachial plexus at the supraclavicular level is cephaloposterior and lateral to the subclavian artery, and paresthesia or muscle stimulation may be elicited before block needle contacts the first rib. When blocking the brachial plexus at the supraclavicular level, the middle trunk (median nerve) is more posterior to the artery and spread of the local anesthetic to this area may be prolonged. If the ulnar nerve distribution is missed with this block, a supplemental ulnar nerve block may be necessary. Also, a superficial cervical plexus block should be added for shoulder surgery as this approach often misses the skin overlying the shoulder. Block of the intercostobrachial nerve in the axilla is necessary if a tourniquet will be used and placed on the upper arm.

Clinical Uses Surgical

• Humerus surgery (including ORIF)

• Elbow surgery

• Wrist and hand surgery

• Upper extremity proximal arteriovenous (AV) fistula surgery

Postoperative Analgesia

For all the surgeries indicated above.

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