Supraclavicular Nerve Block 

Updated: Sep 06, 2018
Author: Alma N Juels, MD; Chief Editor: Meda Raghavendra (Raghu), MD 

Overview

Background

The supraclavicular block was introduced into clinical practice in Germany by Kulenkampff in 1911. Kulenkampff’s recommendation was to advance the needle toward the first rib, in the direction of the spinous process of T2 or T3, which carries an inherited risk for pneumothorax. The high pneumothorax risk was responsible for the technique falling into disfavor. With several modifications, the supraclavicular approach remained a popular choice until the early 1960s.[1, 2, 3, 4]

Eventually, with the combined effect of pneumothorax fear and the introduction of the axillary approach in 1949, the supraclavicular block fell out of favor. In 1978, La Grange described the use of the Doppler probe to identify arteries, which helps to locate the brachial plexus. Kapral et al expanded that idea with the first described ultrasound imaging of the brachial plexus in the supraclavicular position and the needle insertion under ultrasound guidance. Vincent Chan then described the use of both ultrasound and nerve stimulation to perform the block.

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: lateral, posterior, and medial. The medial brachial cutaneous and medial antebrachial cutaneous nerves come of the medial cord. The cords then pass into the axilla and divide into nerve branches: the musculocutaneous, axillary, radial, median, and ulnar nerves (see the image below). The brachial plexus can be blocked anywhere along its course, from the neck to the axilla.

Nerve branches. Nerve branches.

Indications

The supraclavicular block is used for surgeries or postoperative pain control for the upper extremities. It is best for areas below the mid-humerus level. Above the mid-humerus, the shoulder area, an interscalene block would provide better coverage. However, if enough volume is used it can diffuse to the shoulder area.

The major advantage of the supraclavicular block is that the nerves are tightly packed in that area. This gives a very fast deep block, giving it the nickname "the spinal of the arm." Very few needle adjustments are needed once the subclavian artery and the dome of the lung is visualized. The goal is to get around the subclavian artery, where the nerves are located, and stay away from the dome of the lung, avoiding a pneumothorax. This approach has less chance of blocking the phrenic nerve than the interscalene approach.

A disadvantage of the supraclavicular block is the proximity to the pleura, which causes concern for a pneumothorax.

Contraindications

Contraindications include the patient not consenting, allergy to local anesthetics, infection at site of injection, or inability to insert needle or place probe at the needed area due to a splint, cast, or dressing. These are all absolute contraindications.

Relative contraindications are coagulopathy or systemic infection.

 

Periprocedural Care

Patient Education and Consent

Informed consent or written consent should be obtained, reviewing the risk and benefits explained to the patient as well as the positioning and what to expect. 

Equipment

The following equipment is needed:

  • An ultrasound machine with a 8–15 MHZ straight or curved-array probe and sterile ultrasound gel is needed. The higher frequency transducer is used since it is such a superficial block.

  • A needle, usually a 21-gauge or 22-gauge 80-mm block needle, is needed. Use an insulated stimulating needle that can be connected to a nerve stimulator if any doubt exists regarding the nature of any structure that may look like the nerves. These needles tend not to be very echogenic. Specific echogenic needles can be used for ultrasound guided blocks, but the difference tends to be minimal.

  • A nerve stimulator can be used, if wanted in adjunct to ultrasound images or if an ultrasound is available. Use a 21-gauge or 22-gauge insulated needle, with the nerve stimulator 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 patient.

  • Local anesthetic (see below): If you have a good image, 20mL is all you need. Increasing the volume increases the chance of phrenic nerve paralysis. Local anesthetic with a 25-gauge or 27-gauge needle is not necessarily needed for a skin wheal before block needle insertion.

  • Lipid emulsion and resuscitation equipment must be available. The patient needs to have basic monitoring with 3-5 lead EKG, NIBP, and pulse oximetry.

  • Sterile prep such as ChloraPrep (preferred) and sterile ultrasound gel: In the authors’ institution, the authors use a sterile Tegaderm to place over the ultrasound probe; they then place the sterile ultrasound gel the Tegaderm. A printer can be attached to the ultrasound to get still images for the chart.

Patient Preparation

Anesthesia

For surgical anesthesia in adults, a single shot of 30mL of 1.5% mepivacaine plain provides 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 2mg/mL (0.2%) prolongs the block to 4–6 hrs. Another option for immediate surgical block and long acting block is the mixture of 15 ml of 1.5% mepivicaine and 15ml of 0.5% Bupivicaine.

For longer postoperative analgesia, 0.25% ropivacaine or bupivacaine is used and should provide more than 12 hours of pain relief. The onset will be delayed from 5 min to about 20 min and provides both perioperative and postoperative pain control. A combination of both can be used. A maximum of 40cc, taking weight based toxicity of local anesthetic used.

Monitoring & Follow-up

Complications

Complications may include the following:

  • Pneumothorax. The incidence has decreased substantially with ultrasound guidance. Onset of symptoms may take up to 24 hours.

  • Hematoma can occur. To reduce the chance of a hematoma, avoid multiple needle insertions and apply firm pressure after removing needle. Consider risk/benefit in coagulopathic patients.

  • Nerve injury is always a possibility with nerve blocks. Avoid contact with the nerve bundles and advance the needle slowly. Stop when a "pop" is felt entering the nerve sheath. Do not inject if high pressure is felt. Do not inject if 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. Inject slowly and avoid high pressures while injecting.

  • Once again, toxicity can occur with any block. The clinician needs to prevent intravascular injection. 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: To avoid, use strict aseptic technique.

  • Horner syndrome

  • Hoarseness

  • Phrenic nerve palsy (this is less likely than with an interscalene block)

  • One study showed 50% diaphragm paralysis with a supraclavicular block compared with 100% with an interscalene block. This study was with the sole use of a nerve stimulator. With the ability to localize the brachial plexus better with an ultrasound and the need for lower volumes, the incidence of diaphragm paralysis is significantly less.

Preprocedural Planning

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.

 

Technique

Approach Considerations

The block is best performed as an ultrasound-guided block. It has been performed blindly, with a Doppler used to guide the needle around the subclavian artery, with a nerve stimulator and ultrasound/nerve stimulator combination. Due to the high risk of a pneumothorax, the supraclavicular block was no longer performed by most anesthesiologists until the resurgence of the ultrasound as a guide to regional anesthesia. 

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.

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 all complications.[5, 6]

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

Most anesthesiologists today use ultrasound alone without the nerve stimulator.

Supraclavicular Nerve Block

Landmark: Clavicle and subclavian artery

Start at the sternocleidomastoid muscle right above the clavicle. The probe is parallel to the clavicle, moved laterally toward the midpoint of the clavicle; the probe should be in the supraclavicular fossa above the clavicle. The patient is placed semi-sitting; raise the head of the bed about 45° and have the patient turn their head in the opposite direction (see image below).

Correct head position, transducer position, and in Correct head position, transducer position, and in-plane needle insertion. Reproduced with permission.

At this location, the subclavian artery is seen beating above the first rib; it cannot be compressed as opposed to the vein. Sometimes the subclavian artery can be palpated. Pleura are seen on each side of the rib. The rib is bright (see the image below). The provider can stand at the patient’s side, the same side that is being blocked or at the patients head.

White box is area scanned; SA=subclavian artery, S White box is area scanned; SA=subclavian artery, SV=subclavian vein, SAM=scalenus anterior muscle, SMM=scalenus medius muscles, C=clavicle. Reproduced with permission.

The brachial plexus is lateral to the subclavian artery. Once the subclavian artery is visualized, explore the area superficial and lateral until the plexus is seen. It has the characteristic honeycomb appearance. The view can be of multiple nerves or just 2. It helps to rock the probe cephalad to caudal, lateral to medial, to find the best plane to visualize the most nerves from the plexus and get a good quality picture.

The needle is inserted on the lateral side of the probe since the plexus is located lateral to the subclavian artery. The entrance point is 1 cm away from the probe to decrease the angle of insertion, and it is moved from lateral to medial. The needle is placed in the long axis, in plane to the probe, and should be visualized at all times. This is especially important for this block since the needle can cause a pneumothorax if not visualized at all times.

To confirm lung parenchyma, ask the patient to take a deep breath; the characteristic multiple parallel lines of the pleura layers move, and the change in lung appearance occurs. The needle is advanced under direct visualization toward the angle formed by the first rib and the subclavian. A small amount of local anesthetic solution is injected to confirm the location of the needle tip; this can be done while slowly advancing the needle.

Arrows=needle placement in-plane; arrowheads=brach Arrows=needle placement in-plane; arrowheads=brachial plexus nerves; SA=subclavian artery. Reproduced with permission.

The injected volume gently expands the connective tissue surrounding the nerves, which is called hydro dissection. This allows a clear path for the needle, decreasing the chance of nerve damage of the nerves by the needle. The clinician should see the spread of local anesthetic in the angle between the first rib and the subclavian artery. Color Doppler can be done to confirm that the artery is visualized if any doubt exists. The subclavian vein is medial and superficial to the artery and is compressible. Remember to aspirate every 3–5 mL during injection to prevent vascular injection. Keep the nerve bundle centered in the image. If the needle is difficult to visualize, rock the probe back and forth until the needle is visualized.

Nerve Stimulation

Place the patient supine, with the head of the bed at 30°. The patient’s head is turned away from the side being blocked, same as the ultrasound block. ThesShoulder is down, the upper arm by the patient’s side, flexed at the elbow and wrist supinated on patients abdomen. Identify the clavicular head of the sternocleidomastoid (SCM) muscle at its insertion into the clavicle. The area medial to this is considered the "unsafe" zone and is high risk of pneumothorax; the lateral area is safer.

The trunks are short and run very steep above the clavicle, which does not give a large area to work with. The area is about 2.5 cm (1 inch) lateral from the insertion of the SCM to the clavicle (usually at the midpoint of the clavicle). The brachial plexus can usually be palpated at this point as a bump or groove called the interscalene groove. It can be a little medial or lateral to this point but not too far. Where the interscalene groove is palpated is where the needle is placed.

The needle is inserted anteroposterior with a 30° caudal orientation. Advance slowly up to 1.5 cm depending on the amount of subcutaneous tissue. Usually a twitch of the shoulder is seen as the needle approaches the front of the plexus. The needle is advanced caudal, parallel to the midline, perpendicular to the clavicle, at a 10° angle. As the needle is advanced after the shoulder twitch, the pectoralis and triceps will twitch, then the wrist and finger. This corresponds to the upper trunk, middle truck, then the lower trunk. Once the desired twitch is obtained at 1 mA, decrease the amplitude to 0.4–0.5 mA and make sure the desired twitch is still present. The goal is isolated twitch of the fingers only. If the desired twitch is not obtained redirect the needle, do not advance the needle more than 2 cm caudally.

 

Medication

Medication Summary

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

Local Anesthetics

Class Summary

Local anesthetics block the initiation and conduction of nerve impulses. Epinephrine may be coadministered to prolong the duration of anesthetic effects.

Mepivacaine (Polocaine, Prolocaine-MPF, Carbocaine)

For surgical anesthesia in adults, a single shot of 30 mL of 1.5% mepivacaine plain provides 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 2mg/mL (0.2%) prolongs the block to 4-6 hrs.

For longer postoperative analgesia, 0.25% ropivacaine or bupivacaine is used and should provide more than 12 hrs of pain relief. The onset is delayed from 5 min to about 20 min. This can be used for both perioperative and postoperative pain control. A combination of both can be used.

Mepivacaine with or without epinephrine decreases permeability to sodium ions in neuronal membranes. This results in the inhibition of depolarization, blocking the transmission of nerve impulses. Epinephrine prolongs the duration of the anesthetic effects from bupivacaine by causing vasoconstriction of the blood vessels surrounding the nerve axons.

Tetracaine

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

Ropivacaine (Naropin)

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

Bupivacaine (Marcaine, Sensorcaine, Sensorcaine-MPF)

Bupivicaine decreases the permeability of soduim ions in neuronal membranes. This results in the inhibition of depolarization, blocking the transmission of nerve impulses. This agent is an option for longer analgesia. It is more cardiotoxic than ropivicaine.