What Is an Infraclavicular Nerve Block?

An infraclavicular nerve block is injected just below the collarbone to numb the brachial plexus, which provides nerve function to the arm.

An infraclavicular nerve block is a procedure to numb the brachial plexus nerves, which transmit sensation of the arms. An anesthetic injection is administered below the collarbone (clavicle), adjacent to the brachial plexus, to block the transmission of pain signals to the brain.

The brachial plexus is a network of nerves that emerge from the neck (cervical) region of the spine and transmit sensory and motor functions of the shoulders, upper arms and hands. Three main techniques are used to block the brachial plexus:

• Infraclavicular nerve block: administered below the clavicle to numb the hand, forearm, elbow, and most of the upper arm.
• Supraclavicular nerve block: administered above the clavicle to numb the arm below the shoulder.
• Interscalene nerve block: administered in the neck to numb the shoulder and upper arm.

The intercostobrachial nerve transmits sensation from the inner side of the upper arm. The anesthetic injection is administered in the arm, just below the armpit, to block the intercostobrachial nerve.

The infraclavicular nerve block anesthetizes the outer side of the upper arm. The brachial plexus nerve blocks may not adequately anesthetize the intercostobrachial nerve, so this nerve block is usually performed as a supplementary measure.

An infraclavicular block may be performed to provide anesthesia or pain relief (analgesia). An infraclavicular nerve block may also be administered in combination with general anesthesia.

An infraclavicular block is performed:

• Prior to surgical procedures in the
  • Elbow
  • Forearm
  • Hand
• For post-surgical pain relief in the arm
• For pain from a tourniquet applied on the arm
• For making a surgical connection between an artery and a vein (arteriovenous fistula) for hemodialysis

The infraclavicular approach is useful for placing a thin flexible tube (catheter) when continuous analgesia is required for longer periods, because the infraclavicular area has very little movement and poses minimal risk of catheter displacement.

An infraclavicular block is avoided in the following conditions:

• Infection in the injection site
• Allergy to local anesthetics
• Presence of splint, cast or dressing in the area
• Bleeding disorder
• Systemic infection

An infraclavicular nerve block may be performed as an outpatient procedure or in the hospital, depending on the surgical procedure involved.

Anesthesia

The doctor may use one or a combination of the following anesthetic agents:

• Mepivacaine for blocks lasting up to three hours
• Mepivacaine and epinephrine for blocks lasting four hours
• Mepivacaine, tetracaine and epinephrine for blocks of up to six hours
• Bupivacaine or ropivacaine for blocks lasting 12 hours

Preparation

• The patient is in a semi-sitting position.
• Mild sedation is administered.
• The patient’s blood pressure, heart rate and oxygen levels are monitored.
• The injection site is sterilized.

Procedure

The doctor

• May administer the injection
  • at the midpoint below the clavicle, or
  • closer to the arm end of the clavicle.
• Uses ultrasound guidance for accurate positioning of the needle.
• May confirm the correct location of the nerve by stimulating the nerve and producing a finger twitch.
• Inserts the needle deep through the pectoral muscles.
• Aspirates the needle to be certain the needle is not in a blood vessel.
• Slowly injects the anesthetic around the axillary artery and the brachial plexus nerve cords.
• Inserts a catheter through the needle insertion site, if analgesia is required for extended periods.
• Withdraws the needle and waits for 10 minutes for the nerve block to take effect.
• Recovery depends on the surgical procedure performed.

Potential complications of an infraclavicular nerve block include:

• Muscle pain because the needle goes through the pectoral muscles
• Infection at the injection site
• Hematoma
• Bleeding
• Injury to
  • Nerves
  • Blood vessels
  • Lymphatic vessels
• Puncture of the lung (pneumothorax), which is rare
• Local anesthetic systemic toxicity
• Allergic reaction to local anesthetics