Supraclavicular Plumb Bob Technique

The patient's head is turned slightly to the contralateral side. The patient is asked to raise the head slightly off the table so that the lateral border of the clavicular head of the sternocleidomastoid muscle can be identified as it inserts onto the clavicle. This point is marked as the entry point. After skin preparation, an insulated needle is inserted at the entry site as if it were a weight ("plumb bob") under gravitational pull (i.e., in a parasagittal direction) ( Fig. 2026 ). If appropriate nerve stimulation of the forearm or hand is not obtained, the needle is returned to the skin and redirected cephalad in small steps through an arc of 20 degrees. If this is not successful, the needle is returned to the skin and redirected through an arc of 20 degrees in a caudal direction. Once muscle contraction in the forearm or hand is elicited at an mA less than 0.5, 30 mL of local anesthetic is incrementally injected.

ALTERNATIVE TECHNIQUE: PERIVASCULAR SUBCLAVIAN APPROACH

The subclavian perivascular approach ( Fig. 20-27 ) to the brachial plexus has the point of entry at the interscalene

Plumb Bob Approach Supraclavicular Block
Figure 20-26 Supraclavicular block, "plumb bob" technique.

groove, where the subclavian artery pulsation is felt. A 22-G, 50 mm, insulated needle is directed caudad at this point tangential to the dorsal aspect of the subclavian artery. The needle point is seeking the trunks at this position. An associated side effect is that phrenic nerve block occurs in 30% to 50% of patients.

Complications

As with other supraclavicular blocks, pneumothorax can occur with an incidence between 0.5% and 5%. The incidence may be higher in patients in whom the apex of the lung is positioned more cephalad (e.g., patients with COPD, pediatric patients). Another possible complication is subclavian artery puncture.

Physiologic Changes

Anesthesia occurs in the whole arm up to the shoulder, except inside the upper third of the upper arm. There is sympathetic block in the same regions along with loss of sweating and increased temperature.

Prevention of Deleterious Effects

1. Puncture of the subclavian artery or lung or entering epidural and subarachnoid space should be avoided.

2. The stellate ganglion may be blocked, especially with large volumes.

Plumb Bob Techniques Nerve Block

Figure 20-27 Subclavian perivascular block. Subclavian-perivascular approach to the brachial plexus. Note the point of entry at the interscalene groove, where the subclavian artery pulsation is felt. A 22-gauge 1/-inch needle is directed caudad at this point tangential to the dorsal aspect of the subclavian artery. The needle point is seeking the trunks at this position. (From Raj PP: Clinical Practice of Regional Anesthesia. New York, Churchill Livingstone, 1991, p 289.)

Figure 20-27 Subclavian perivascular block. Subclavian-perivascular approach to the brachial plexus. Note the point of entry at the interscalene groove, where the subclavian artery pulsation is felt. A 22-gauge 1/-inch needle is directed caudad at this point tangential to the dorsal aspect of the subclavian artery. The needle point is seeking the trunks at this position. (From Raj PP: Clinical Practice of Regional Anesthesia. New York, Churchill Livingstone, 1991, p 289.)

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