Brachial Plexus Nerve Block
Brachial plexus block
- This is the second most commonly practised block after central neuraxial block (spinal & epidural anaesthesia).
- Brachial plexus block is used for upper limb surgeries.
- Brachial plexus can be blocked by 4 approaches : –
1. Interscalene approach
- Brachial plexus is blocked between anterior and middle scalene.
- This approach is not used routinely due to close proximity of vital structures.
- Ulnar nerve is usually spared by this approach because injection is given in close proximity of upper nerve roots and inferior nerve roots (C8-T 1) may be spared.
- This technique provides excellent anaesthesia and analgesia for shoulder and upper arm procedures. (in contrast to other three approaches which do not provide adequate shoulder anaesthesia).
- Complications include Horner syndrome (due to stellate ganglion block), phrenic nerve block, intravascular injection into carotids and epidural or intrathecal injections.
2. Supraclavicular approach
- This is the most commonly used approach.
- It involves the injection of local anaesthetic in close proximity to the trunks of the brachial plexus by inserting the needle lateral to subclavian vessels.
- The supraclavicular block is performed where the brachial plexus is most compact, consequently, it produces reliable and rapid onset anaesthesia and is particularly useful in a fast paced ambulatory surgery centre.
- Pneumothorax is the most common complication. Other complications include phrenic nerve block, intravascular injection in subclavian artery or vein, Horner syndrome, hematoma formation.
3. Infra-clavicular approach
- Infraclavicular block involves the injection of local anaesthetic in close proximity of cords of the brachial plexus.
- The axillary nerve may be spared as this nerve exits the brachial plexus sheath proximal to the level of infraclavicular block.
4. Axillary approach
- Axillary block involves the injection of local anaesthetic in close proximity of terminal branches of the brachial plexus.
- The major disadvantage of this approach is that mucocutaneous and intercostobrachial nerves are spared.
- So arm surgery cannot be performed. In contrast to interscalene approach, most intense block occur in (C7-T1) ulnar dermatomes and least in C5-C6 dermatomes.
- Most commonly used approach of brachial plexus block is Supraclavicular.
- Exposure of left subclavian artery by supraclavicular approach does not require cutting of Scalenus medius.
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