What is a supraclavicular nerve block?
A supraclavicular nerve block is a procedure to block the sensation in the arm below the shoulder. An anesthetic injection is administered in the area above the collarbone (clavicle) close to the network of nerves (brachial plexus) that provides sensation to the upper extremities. An alternative to supraclavicular nerve block, the interscalene nerve block, is also used to anesthetize the same array of nerves. In an interscalene block, the injection is administered in the neck, closer to the nerve roots.
An interscalene block provides more effective anesthesia to the shoulder but may not effectively block some parts of the hand and fingers. With sufficient anesthetic, a supraclavicular nerve block can diffuse to the shoulder area as well.
A supraclavicular nerve block is the quickest and most effective block for the entire arm because the nerves are tightly packed in the targeted anatomical region (brachial plexus). This approach also carries less chances of blocking the phrenic nerve, which is responsible for the diaphragm’s function that is crucial for breathing.
History and development
The supraclavicular nerve block was first introduced in 1911. Originally, however, the procedure carried a high risk for lung collapse (pneumothorax) because the lung is near the injection site. With the use of ultrasonography for visualizing the needle tip, blood vessels in the region, and the lung’s protective membrane (pleura), pneumothorax risk is now greatly reduced.
Why is a supraclavicular nerve block performed?
A supraclavicular nerve block is usually performed prior to surgeries and for post-operative pain relief (analgesia) in the upper extremities. It may be combined with a wrist block for increased effect in the hand and fingers.
A supraclavicular nerve block is avoided in the following situations:
How is a supraclavicular nerve block performed?
A supraclavicular nerve block may be performed as an outpatient procedure for chronic pain management. Supraclavicular nerve block performed before surgery and for post-surgical pain may involve hospitalization for a day or two, depending on the complexity of the surgery.
- The patient lies flat or semi-reclines, with their face turned away from the side where the nerve block is administered.
- The injection site is sterilized with antiseptic.
- Mild sedation may be administered.
- The patient’s heart rate, blood pressure and oxygen levels are monitored.
- Uses ultrasound guidance during the entire procedure for accurate positioning, angle of the needle, and administration of the anesthetic.
- May use a nerve stimulator to confirm the correct location of the nerve by producing a tingling sensation (paresthesia).
- Inserts the needle and injects anesthetic.
- Aspirates the needle to ensure the needle has not punctured a blood vessel.
- Tells the patient to take a deep breath to make sure the pleura is not punctured.
- Advances the needle close to the brachial plexus, making sure to avoid hitting the nerve directly.
- Injects the anesthetic slowly.
- Withdraws the needle and waits approximately 10 minutes for the nerve block to take effect.
- Inserts a thin flexible tube (catheter) through the needle, to provide continuous post-surgical pain relief, if required for more extended periods.
After the procedure
- The patient will be monitored for a few hours.
- Recovery will depend on the type of surgery performed.
How long does a supraclavicular nerve block last?
The duration of the effects of a supraclavicular nerve block depends on the type of anesthetic agent used.
- During surgery, mepivacaine provides fast-acting anesthesia, which sets in within five minutes and lasts up to three hours.
- For post-surgical pain relief, ropivacaine or bupivacaine is used, which may take up to 20 minutes to take effect but lasts for more than 12 hours.
- For chronic pain relief associated with inflammation, a combination of methyl prednisolone and bupivacaine may provide relief for months.
What are the risks and complications of a supraclavicular nerve block?
Complications include the following:
- Pneumothorax, though this risk is very low with ultrasonography
- Infection at the injection site
- Nerve injury resulting in neuropathy
- Injury to blood or lymphatic vessels
- Hoarse throat because of accidental block of the laryngeal nerve
- Local anesthetic systemic toxicity
- Anesthetic spreading to sympathetic nerves, leading to Horner syndrome, a condition affecting one side of the face with symptoms such as:
- Paralysis of the diaphragm
- Phrenic nerve palsy (asymmetrical elevation of the diaphragm)