|Level of blockade||Coverage distribution (Figure 135-1)|
|Cords of brachial plexus|
- Whole upper extremity including axillary nerve
- Usually not blocked: suprascapular nerve (innervating supraspinatus, infraspinatus, and posterior 70% of glenohumeral joint)
Figure 135-1. Area Blocked by an Infraclavicular Block
Surgery of the upper extremity below the shoulder, as the suprascapular nerve is usually spared.
Significant coagulopathy, as vessel puncture common (with NS technique), and this is a deep block poorly amenable to compression.
Pacemaker in the area where the block is to be performed.
- Paracoracoid approach (Figure 135-2):
- Patient supine, arm by the body, forearm on patient's chest
- Locate the coracoid process, caudad to the clavicle and medial to the humeral head
- From the most salient point of the coracoid, measure 2 cm caudad and 2 cm medial: this is the needle insertion point
- After prepping and local anesthesia, insert a 100 mm needle (unless patient very thin or small: use a 50 mm needle in that case) vertically toward the floor. Set PNS at 1.2 mA, 2 Hz, 0.1 millisecond
- The needle must never be directed medially: risk of pneumothorax
- If no response obtained, bring needle back to skin and redirect in 5° increments caudad or cephalad, but always in a parasagittal plane
- Elicit an acceptable response (see below); adjust needle position while decreasing current until response maintained at 0.4 mA
- If using a short-acting (chloroprocaine) or intermediate-acting (lidocaine, mepivacaine) local anesthetic, aspirate, and then inject the whole volume (40 mL) in a fractionated fashion
- If using a long-acting (bupivacaine, ropivacaine) local anesthetic, aspirate, and then inject one half of the volume (20 mL) in a fractionated fashion. Retract the needle by 2–3 cm:
- If an “ulnar” response was obtained, redirect needle cephalad
- If any other response was obtained, redirect needle caudad
- Elicit another acceptable response (see below); adjust needle position while decreasing current until response maintained at 0.4 mA; aspirate, and then inject one half of the volume (20 mL) in a fractionated fashion
- Performing a single injection with a long-acting LA can lead to delayed onset in the areas not covered by the nerve initially stimulated, up to 45 minutes after the injection
- Subclavicular approach:
- This technique inserts the needle just caudad to the midpoint of the clavicle. It is popular in Europe, and gives good results in experienced hands, but the risk of pneumothorax is higher
Figure 135-2. Landmarks for Neurostimulation-Guided Paracoracoid Technique
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