Infraclavicular Nerve Block

 

Background

Several techniques for infraclavicular nerve blocks have been described. The coracoid approach was first described by Whiffler in the British Journal of Anaesthesia in 1981. This technique was most commonly used with nerve stimulation. The use of ultrasound offers more flexibility in approaches, giving the provider different choices for needle insertion depended on patients’ anatomy and best ultrasound image. [12]

All upper extremity blocks involve the brachial plexus. The brachial plexus arise from the anterior rami of C5-8 and T1 with some contribution from C4 and T2. The rami unite to form superior, middle, and inferior trunks. They occupy the space between the anterior and middle scalene muscles. Each trunk divides into anterior and posterior divisions, which rejoin to form 3 cords: the lateral, posterior, and medial. The medial brachial cutaneous and medial antebrachial cutaneous nerves come off the medial cord. The cords then pass into the axilla and divide into nerve branches: the musculocutaneous, axillary, radial, median, and ulnar (see the image below). [34The brachial plexus can be blocked anywhere along its course, from the neck to the axilla.

Formation of brachial plexus rami, trunks, divisioFormation of brachial plexus rami, trunks, divisions, cords, roots and nerves.

Indications

This block provides anesthesia and analgesia for the upper extremity. It works best for analgesia below the elbow. It can provide good analgesia for tourniquet pain but is not suited for the shoulder area. It will not anesthetize the axilla or the proximal medial arm, missing the intercostal and medium cutaneous brachii nerves. It blocks the brachial plexus below the level of the clavicle close to the coracoid process. [4This is a good place to place a continuous catheter because it is an area with little movement and therefore less chance of being displaced.

Contraindications

Absolute contraindications include the following:

  • Patient not consenting

  • Allergy to local anesthetics

  • Infection at site of injection or if unable to insert needle or place probe at area needed due to a splint/cast/dressing

Relative contraindications include the following:

  • Coagulopathy

  • Systemic infection

Landmarks

The infraclavicular block can be considered the same block as the axillary block and has the advantage of not having to move the arm over the patient’s head. [5Two main approaches exist. The proximal one is under the clavicle at the midpoint. The distal one is at the level of the coracoid process. Under the clavicle, the plexus are set up as divisions, as described above. They are lateral to the axillary artery proximally and rotate to surround the artery as it approaches the coracoid process. The boundaries of the infraclavicular fossa are the pectoralis minor and major anteriorly, ribs medially, clavicle and coracoid process superiorly, and humerus laterally. With the arm in adduction, it is represented on the skin with the clavicle as the superior base, the skin of the thoracic cage medial, and the medial side of the upper as the lateral wall (see the image below). This block can be deep depending on patient’s subcutaneous tissue.


Innervation of the arms and hands. Innervation of the arms and hands.

Infraclavicular Nerve Block Periprocedural Care





Patient Education and Consent

The block should be explained to the patient including risks and benefits. There should be informed consent or a signed consent depending on institutional rules. This should be done before any sedation is given.

Equipment

The block can be done with a nerve stimulator, an ultrasound, or both. 

The ultrasound probe can be an 8–12 MHZ or a curved linear frequency 3–7 MHZ. [6The advantage of a curved probe is it offers a wider field of view. Depending on the thickness of the patient’s chest, the provider can use a linear high-frequency probe.

An 80–100 mm 18–22 gauge block needle is used. The longer length may be needed due to the depth of the nerve bundle at this location. A large-bore needle is preferred when the nerves are deep; this allows better visualization of the needle. If any doubt exists regarding the nature of the structures that look like nerves, an insulated stimulating needle can be connected to a nerve stimulator. These needles tend not to be very echogenic. Specific echogenic needles for ultrasound-guided blocks exist, but the differences tend to be minimal. The needle crosses thick pectoralis muscles in the chest; this can be painful, requiring sedation to keep patients comfortable.

A nerve stimulator may be used as an adjunct to ultrasound images or if an ultrasound is not available. A nerve stimulator is set at 1–1.5 mA pulse frequency of 1 Hz and pulse duration of 0.1 msec. Attach the needle to the nerve stimulator and place the grounder on the patient with an EKG pad.

If a good image is available, 20 mL of local anesthetic is all that is needed (see Anesthesia). Increasing the volume increases the chance of phrenic nerve paralysis. Local anesthetic with a 25-gauge or 27-gauge needle may be needed for a skin wheal and to numb the pectoralis muscle before block needle insertion, usually 1–2% lidocaine.

Resuscitation equipment and medication must be available, including lipid emulsion, intralipid in case of bupivicaine toxicity

Basic monitoring should be in place, with 3-5 lead EKG, NIBP, and pulse oximetry. [3]

Sterile prep such as ChloraPrep (preferred) and sterile ultrasound gel are needed. It is preferred to let the ChloraPrep for at least three minutes before inserting the needle. The authors use a sterile Tegaderm to place over the ultrasound probe and place the sterile ultrasound gel over the Tegaderm. [3A printer can be attached to the ultrasound to get still images for the patient’s record.

Anesthesia

For surgical anesthesia in adults, a single shot of 30 mL of 1.5% mepivacaine plain will provide close to immediate (5 min) to 2–3 hrs of surgical analgesia. For longer surgical anesthesia, up to 3–4 hrs, 1:400,000 epinephrine is added to the solution. The block completely resolves about 2 hrs later. If a longer block is needed, adding tetracaine at 2 mg/mL (0.2%) prolongs the block to 4–6 hrs. Another option for fast onset and long-term analgesia is mixing 15 ml of 1.5% mepivicaine with 15 ml of 0.5% bupivicaine and injecting. Sometimes a smaller volume can be used if you have a nice spread around the nerves.

For longer postoperative analgesia, 0.25% ropivacaine or bupivacaine is used and should provide more than 12 hrs of pain relief. The onset will be delayed from 5 min to about 20 min. For both perioperative and postoperative pain control, a combination of both can be used. No more than 40 ml should be injected taking into consideration the patient's weight and the toxicity dose of the local anesthetic used.

Positioning

Patient is in a semi-sitting position with arm to be blocked down and at 45°.

Patient Preparation

If the block is done before surgery, the patient usually recieves some anxiolytics and opioids before proceeding with the block. At minimum, a pulse oximeter is placed. A nasal cannula with oxygen is started and a timeout performed with a nurse and the anesthesiologist. The patient is then sedated, if they can tolerate it, by giving some midazolam and fentanyl. 

If the block is done after surgery, standard PACU monitors are on and a timeout is done.

Infraclavicular Nerve Block Technique


Needle Placement – Ultrasound Guidance

For the proximal approach, place the transducer parallel and below the midpoint of the clavicle. Most medial will be the axillary vein; the axillary artery is next in the center, and the brachial plexus divisions are most lateral. The needle is advanced in or out of the plane. The best view is obtained going from lateral to medial, keeping the needle in plane; the needle can then be viewed along its entire path. [1]

For the coracoid approach, the ultrasound probe is placed close to the coracoid seeking the optimal image of the axillary artery with the surrounding nerves. The probe may need to be rotated to obtain optimal view of plexus, which is diagonally in the infraclavicular area. The nerve bundle is deeper with the coracoid approach, requiring a steep angle of 45°, making visualization of the needle difficult. Also, a wide anatomic variation of the cords in this region exists, and even only 2 cords can exist instead of 3. Arm abduction is recommended to stretch the cords, bringing them closer together and more anterior, making it easier to see and block.

This block can be done with a lateral to medial approach or a cephalad to caudad approach. [5]

The cephalad-to-caudad approach. The cephalad-to-caudad approach.

 

Ultrasound image of the needle in plane with localUltrasound image of the needle in plane with local anesthetic posterior to the axillary artery. Arrows = block needle, AA = axillary artery, LA = local anesthetic posterior to the artery.

The aim with both approaches is to get local anesthetic around all cords; this is best accomplished by injecting posterior to the axillary artery and getting a U-shaped spread around the artery. Maximum block success is best accomplished by injecting 10 mL posterior to the artery, 6 o'clock, to get the posterior cord. For the lateral cord, withdraw the needle slightly and aim for the 9 o'clock position around the artery and inject another 10 mL of local anesthetic. This should get a good spread around the artery. If the 3 o'clock position around the artery looks like it did not get a good spread of local anesthetic, injecting some local anesthetic in that area (between the axillary artery and vein where the medial cord lives) may be necessary, although it is usually not necessary. This results in 20–30cc total volume injected. Usually less is needed if a circumferential spread is obtained with the first two injections-posterior cord and lateral cord spreading to the medial cord. [4 Keep the image of the nerve bundle centered. If it is difficult to visualize the needle, rock the probe slowly until the needle can be seen. Inject slowly without too much pressure.

Ultrasound orientation of the muscles, arteries, aUltrasound orientation of the muscles, arteries, and nerves in a transverse view. Short axis (transverse view)-AA=axillary artery, Arrowheads=cords, AV=axillary vein, PMM=pectoralis major, PMIM=pectoralis minor 9-12 o‘clock is cephalad to artery=lateral cord, 6-9 o'clock is posterior=posterior cord, 3-6 o'clock is caudad is medial cord. Medial cord is often hard to visualize.

Nerve Stimulator for Infraclavicular Block

The patient is supine, shoulder down, and the arm is abducted 30–45°. This moves the neuromuscular bundle away from the thoracic cage, which decreases the chance of a pneumothorax. Palpate the coracoid process; the needle is inserted 2 cm caudal and 2 cm medial to the coracoid process. The needle is attached to the nerve stimulator and advanced in the anteroposterior direction. The needle first passes through the pectoralis muscles, major and minor, producing a visible twitch. Continue deeper to get to the brachial plexus. If no twitch is obtained, usually redirecting caudally but occasionally cephalad will locate the nerve trunk. You are looking for finger twitching. 

Complications

The following complications may occur:

  • Muscle pain from needle insertion through the pectoralis major and minor can occur.

  • Gemstones can be large once again due to the muscle penetration.

  • Hematomas can occur. To reduce the likelihood of a hematoma, avoid multiple needle insertions and apply firm pressure after removing needle. Consider risk/benefit in patients undergoing coagulopathy.

  • Pneumothorax is possible but extremely rare; it is not as high a risk as with interscalene or supraclavicular blocks because the needle is advanced away from the chest cavity.

  • Nerve injury is always a possibility with nerve blocks. Avoid contact with the nerve bundles, and advance needle slowly. Stop when a "pop" is felt entering the nerve sheath. Do not inject if high pressure is felt. Do not inject if the patient experiences pain. Readjust the needle when the above scenarios are experienced. Most of the time, the needle needs to be withdrawn slightly. This is an extremely rare complication.

  • Toxicity can once again occur with any block, and intravascular injection needs to be prevented. Aspirate every 3–5 mL. Inject slowly to avoid injecting local anesthetics into smaller vessels and lymphatics that have been punctured during needle insertion.

  • Infection is avoided by using strict aseptic technique

Approach Considerations

It is unusual to only use a nerve stimulator unless you do not have an ultrasound available or have not been trained to use the ultrasound. Nerve stimulation is uncomfortable for the patient. 

If the image is poor or you want to use less volume, it is helpful to use both the ultrasound and the nerve stimulator. Using the ultrasound will allow you to visualize the needle in the correct area and the nerve stimulator will allow you to optimize the exact location to inject the local anesthetic. This is especially helpful if the anatomy is distorted or the view is poor.

A randomized comparative study showed fewer complications when the ultrasound and nerve stimulator where both used. [7]

Studies comparing the ultrasound guided technique alone and the nerve stimulator technique alone have shown ultrasound guidance to be superior as far as procedural time, quality of the block, and vascular complications. [8]

Most anesthesiologists today use the ultrasound alone without the nerve stimulator.


Infraclavicular Nerve Block Medication


Medication Summary

The goal of pharmacotherapy is to achieve pain control perioperatively or postoperatively.

Local Anesthetics

Class Summary

Mepivacaine, bupivacaine and ropivacaine are all amide local anesthetics. They work by decreasing the permeability to sodium ions in neuronal membranes. This results in the inhibition of depolarization, blocking the transmission of nerve impulses. Mepivacaine has a fast onset, 5 minutes, but a short duration. Duration can be prolonged by 3 hours with 1:400,000 of epinephrine added. Bupivacaine and ropivacaine are both used for longer analgesia, more than 12 hours, but have a longer onset, about 20-plus minutes. Ropivacaine has a safer side-effect profile being less cardiotoxic.

Tetracaine is an ester local anesthetic. It works the same as the amides by decreasing the permeability to sodium ions in neuronal membranes. This results in the inhibition of depolarization, blocking the transmission of nerve impulses. Tetracaine has a slow onset with a long duration.

Mepivacaine (Carbocaine, Polocaine, Polocaine-MPF)

Mepivacaine decreases permeability to sodium ions in neuronal membranes. This results in the inhibition of depolarization, blocking the transmission of nerve impulses.

Bupivacaine (Marcaine, Sensorcaine, Sensorcaine MPF)

Bupivacaine decreases permeability to sodium ions in neuronal membranes. This results in the inhibition of depolarization, blocking the transmission of nerve impulses. It is a longer acting-agent. It is more cardiotoxic than ropivacaine.

Ropivacaine (Naropin)

Ropivacaine decreases permeability to sodium ions in neuronal membranes. This results in the inhibition of depolarization, blocking the transmission of nerve impulses. It is a longer-acting agent.

Tetracaine (Tetcaine, Tetracaine ophthalmic)

Tetracaine decreases permeability to sodium ions in neuronal membranes. This results in the inhibition of depolarization, blocking the transmission of nerve impulses. This is an option for longer analgesia.

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