Supraclavicular brachial plexus block (ultrasound)
Citation, DOI & article data
A Supraclavicular brachial plexus block is indicated for establishing sensory and motor blockade of the upper extremity, including the humerus, elbow, forearm, wrist and hand.
- necessity to provide analgesia of the upper extremity for:
Absolute and relative contraindications differ based on practice pattern, but typically include:
- overlying infection
- severe coagulopathy
- local anesthetic allergy
- patient refusal
- pre-existing neuropraxia/neuropathy
- insufficient pulmonary reserve to tolerate potential phrenic nerve blockade
A full neurovascular exam should be performed and documented, and consent should be obtained.
Positioning/room set up
Vascular access should be obtained, and the patient should be placed on a cardiac monitor. The ultrasound machine should be optimally positioned for ergonomic visualization during the procedure, typically on the opposite side of the bed facing the operator at the head of the bed. The patient is positioned supine with their head rotated toward the contralateral side and ideally placed in a semi-Fowlers position.
- ultrasound machine with linear transducer
- sterile probe cover and gel
- nerve block tray
- local anesthetic of choice (20-25 mL)
- normal saline flushes
- short bevel, 22 gauge, 5cm insulated stimulating needle 1
- nerve stimulator
- pressure monitoring system (opening pressure)
- sterile gloves, gown
- chlorhexidine or other appropriate antiseptic
The relevant anatomy is first defined, starting with the probe in a coronal/oblique orientation just posterior to the midpoint of the clavicle in the sternoclavicular triangle. The anechoic, pulsatile subclavian artery is often the most immediately conspicuous sonographic landmark, seen in its short axis as it traverses the cortex of the first rib. The anterior and middle scalene muscles will be anteromedial and posterolateral to the neurovascular structures of interest. The subclavian vein is typically not seen in this window, passing anterior to the anterior scalene to coalesce with the internal jugular vein.
The trunks of the brachial plexus, having formed from a conglomeration of the roots in the interscalene groove, may be appreciated as a collection of stacked, hypoechoic ovals bound within an investing hyperechoic sheath. The trunks should be found just superficial and lateral to the artery.
Care should be made to note the pleura just deep to the first rib, as well as search for any blood vessels which would intersect with the planned needle path. Color flow Doppler interrogation of the tentative needle trajectory, as well as the target structure itself, should be undertaken, with particular attention to the dorsal scapular artery, as well as the transverse cervical and suprascapular arteries 2.
After placing a superficial wheal of local anesthetic at the planned entry point the block needle may be introduced. Combined used of nerve stimulation, constant in-plane visualization of the needle tip, sequential hydro-localization, and injection pressure monitoring should be adhered to in the usual manner.
The standard vector of approach is a shallow lateral to medial; the planned needle course should aim to enter the connective tissue sheath investing the plexus and terminate at the intersection of the 1st rib, the subclavian artery, and the inferior trunk of the brachial plexus (commonly referred to as the "corner pocket") having gained entry to the sheath surrounding the plexus at this level at the lateral/inferior-most aspect 3.
After confirming negative aspiration and low pressure, 10-15 mL of local anesthetic is then injected with the desired effect manifest as the plexus/inferior trunks being mobilized cephalad. The needle should then be withdrawn and, in a similar manner, insinuated between the middle and upper trunks to deposit the remaining local anesthetic 1.
Repeat neurovascular exam should be immediately performed. Type of block, anesthetic, and time procedure was performed should be enumerated in the medical record. Limb should be immobilized and patient educated on follow-up precautions.
- local anesthetic systemic toxicity
- vascular puncture
- hemi-diaphragmatic paralysis 6
- blockade of the cervical sympathetic chain
- miosis, ptosis, anhydrosis
- often referred to as Horner syndrome
- recurrent laryngeal nerve damage
- pneumothorax 7
An effective supraclavicular brachial plexus block will typically produce:
- dense sensory blockade in C5 through C8 dermatomes
- some degree of motor blockade in the terminal branches of the brachial plexus
- brachial plexus nerve blocks
- interscalene brachial plexus block
- costoclavicular brachial plexus block
- infraclavicular brachial plexus block
- axillary brachial plexus block
- point of care ultrasound
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