CHAPTER 8 Upper limb blocks
Interscalene block
Use this block for anaesthesia/analgesia of the shoulder joint (dislocation reduction), arm, elbow, and proximal forearm injuries or amputations (Fig. 8.1).
Fig. 8.1 Anatomical diagram of the brachial plexus in the neck and proximal upper limb. The insets show the relative positions of the artery and the nerves in the supraclavicular, infraclavicular and axillary regions as seen on ultrasound.
Landmark technique
The interscalene approach to brachial plexus blockade results in anaesthesia of the shoulder, arm, and elbow. It is not consistently reliable for anaesthesia of the hand because the C8 and T1 nerve roots are frequently not blocked, and more distal approaches to the brachial plexus, such as the supraclavicular, infraclavicular or axillary blocks, are more appropriate. The traditional interscalene block relies on the injection and dispersion of a large volume of local anaesthetic within the fascial envelope bordered by the anterior and middle scalene muscles to accomplish blockade of the brachial plexus. This block can be performed at the level of the cricoid cartilage (C6) or slightly more inferiorly, closer to the clavicle. With the more inferior approach, the interscalene groove is shallower and easier to identify and the needle insertion point is much more lateral, which makes vascular puncture rare. This approach is also more suited to those not performing the block regularly.
Preparation
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Position the patient supine or in semi-Fowler’s position with the head facing away from the side to be blocked. Position the patient’s arm comfortably by their side and ask them to hold their shoulder down, as though they are reaching for their knee.
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Mark the important landmarks with a skin marker (
Fig. 8.2):
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The posterior border of the clavicular head of the sternocleidomastoid muscle. Ask the patient to turn their head away from the side to be blocked because this tenses the sternocleidomastoid muscles and makes it more prominent. Then ask the patient to lift their head off the table while facing away. This also helps to identify the posterior border of the clavicular head of the sternocleidomastoid muscle.
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The external jugular vein. Ask the patient to try to sit up (or sit forward). This manoeuvre flattens the skin of the neck and helps to identify the interscalene groove, and the Valsalva manoeuvre distends the external jugular vein.
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The interscalene groove. While palpating the posterior border of sternocleidomastoid, ask the patient to forcefully sniff. This tenses the scalene muscles and the interscalene groove becomes more prominent.
Technique
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Prepare the field by cleaning the skin with an antiseptic solution and positioning sterile drapes.
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Identify the target area for the initial needle insertion – the interscalene groove, at about the level of the cricoid cartilage, or slightly inferiorly. The most common error is inserting the needle too far anteriorly. Examine the anatomical landmarks carefully.
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Raise a superficial weal of local anaesthetic at the needle insertion site.
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Puncture the skin at the target point with a 25 mm to 50 mm nerve-block needle (
Fig. 8.3A–C). Direct the needle perpendicular to the skin surface – slightly medially, inferiorly 30° to 45° and posteriorly aiming at the transverse process of C6. If you are using a more inferior puncture site (25 mm above the clavicle), insert the needle perpendicular to the skin surface taking care not to aim superiorly. The inferior angle of the needle is important to decrease the risk of inadvertent entry into one of the neural foramina.
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Advance the needle 10 to 20 mm until paraesthesias are elicited.
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An alternative method is to use a parasagittal approach with the needle held parallel to the scalene muscles and aimed inferiorly towards the midpoint of the clavicle.
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If you are using a nerve stimulator, insert the needle using the same technique. Appropriate twitches include pectoralis, deltoid, triceps, biceps or any muscle of hand or forearm, but not the trapezius.
•
Aspirate. If no flashback of blood is obtained, inject 30 to 40 mL of local anaesthetic slowly with intermittent aspiration to rule out intravascular injection. Slow injection increases block success and decreases complications. If resistance to injection, severe paraesthesias or cramping pain sensations occur with initial injection, then the needle should be withdrawn by 1 to 2 mm to avoid intraneural injection. Use the higher end of the volume range if C8/T1 anaesthesia is desired (remembering that larger volumes are associated with more undesirable effects for this particular block).
•
The onset of anaesthesia with lidocaine is from 5 to 15 minutes and with bupivacaine is from 10 to 20 minutes; duration of anaesthesia is 3 to 6 hours and 8 to 10 hours, respectively; duration of analgesia is 5 to 8 hours and 16 to 18 hours, respectively.
Precautions
The interscalene block is very safe if used appropriately and carefully. Avoid using this block in patients who have significant chronic respiratory disease or patients with respiratory distress, as well as in patients with contralateral phrenic nerve or recurrent laryngeal nerve paralysis.
Complications
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Inadvertent total spinal anaesthesia is a potentially serious complication resulting from incorrect needle placement or from local anaesthetic tracking proximally within the nerve root sheath.
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Vertebral artery injection can result in a rapid onset of central nervous system toxicity.
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Phrenic nerve block occurs frequently, so do not use this block bilaterally or in patients with respiratory compromise.
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Recurrent laryngeal, vagus, and cervical sympathetic nerves are often blocked.
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Pneumothorax can occur as the cupola of the lung may be pierced by a poorly directed needle.
Ultrasound technique
This technique is a simple, easy-to-use method, does not require a nerve stimulator, and allows for smaller volumes of local anaesthetic to be used. It allows precise visualisation of the significant structures and avoids misadventures from misplacement of the needle. It is a useful technique for the ED.
Preparation
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Position the patient supine or in semi-Fowler’s position with the head facing away from the side to be blocked.
•
Rest the arm comfortably by the patient’s side or across the abdomen.
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Use a linear high-frequency probe (10 to 15 MHz is ideal) and select an appropriate pre-set application.
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Identify the area to begin the scan – either the midline of the neck or the supraclavicular fossa, depending upon which scan strategy is employed (
Fig. 8.4).
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Prepare the field by cleaning the skin with an antiseptic solution and positioning sterile drapes. Cover the probe with a sterile probe-sheath and apply sterile ultrasound gel to the area of the interscalene groove.
Technique
In-plane approach (Fig. 8.6)
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Identify the hypoechoic nerve roots in their transverse axis in an area convenient to block.
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Raise a weal of local anaesthetic at the needle insertion target with a 27G needle.
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Insert a 25 mm to 50 mm 22G nerve-block needle on the lateral end of the ultrasound probe.
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Advance the needle towards the edge of the nerves while visualising the entire length of the needle in real time.
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Aim to contact nerve roots in the centre of the interscalene groove from the lateral side; avoid injection close to the neural foramina.
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Track real-time needle movement to prevent inadvertent entry through the neural foramina.
Out-of-plane approach (Fig. 8.7A&B)
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Identify the hypoechoic nerve roots in their transverse axis in an area convenient to block.
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Line up the nerve target at the midpoint of the screen. The needle insertion point will correspond to the exact centre of the transducer.
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Raise a weal of local anaesthetic at the needle insertion target with a 27G needle.
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Insert a 25 mm to 50 mm 22G nerve-block needle on the superior or inferior side of the ultrasound probe.
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Observe tissue and needle movement as the needle is advanced towards the target. Aiming for the side of the nerve bundle rather than the centre makes needle placement more accurate.
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Clear identification of the needle tip may require the probe to be angled back and forth.
The injection process
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Slowly inject local anaesthetic around the nerve roots by positioning the needle in the centre of the interscalene groove, adjacent to the nerve sheath. Aspirate frequently to avoid inadvertent intravascular injection. If resistance to injection, severe paraesthesias or severe cramping pain are provoked in the limb during injection, immediately withdraw the needle by 1 to 2 mm to avoid intraneural injection.
•
Observe the local anaesthetic spread during injection. A hypoechoic collection will appear adjacent to and then spread around the nerves.
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An expansion of the tissue in the interscalene groove indicates a correct positioning of the local anaesthetic injection; expansion within the scalene muscle indicates intramuscular injection and the needle should be repositioned.
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Reposition the needle at least once to ensure complete circumferential local anaesthetic spread around the nerve roots.
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The volume of local anaesthesia introduced appears to be directly related to side effects and complications of the interscalene block. Phrenic nerve blockade is more frequent when volumes greater than 10 mL are injected. The use of ultrasound allows for smaller volumes to be placed accurately and effectively. Inject 10 mL of local anaesthetic or just enough that the nerve roots are visualised to be completely surrounded by hypoechoic fluid. Injection of as little as 5 mL of local anaesthetic within (rather than around) the nerve sheath itself can produce an effective block.
Supraclavicular block
Landmark technique
The supraclavicular block is performed below the level of the nerve roots at a point where the brachial plexus trunks have formed and are contained within a neural sheath. This approach produces a rapid-onset block with a predictable, dense anaesthesia. The supraclavicular block can be used to provide anaesthesia and analgesia for the upper limb distal to the shoulder.
Preparation
•
Position the patient supine or in semi-Fowler’s position with the head facing away from the side to be blocked. Rest the patient’s arm comfortably across their abdomen.
•
Mark the important landmarks with a skin marker (
Fig. 8.8):
•
The posterior border of the clavicular head of the sternocleidomastoid muscle at the point of insertion onto the clavicle (ask the patient to lift their head off the table while facing away, as this helps to define this landmark).
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Draw a line on the neck parallel to the midline through this point to demarcate the lateral extension of the cupola of the lung. The area medial to this line is a danger area because of the risk of pneumothorax.
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The point of pulsation of the subclavian artery should be marked.
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The target point for needle insertion is approximately 25 mm lateral to the line (as a margin of safety) and should be marked on the skin.
Technique
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Prepare the field by cleaning the skin with an antiseptic solution and positioning sterile drapes.
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Identify the target area for needle insertion – about 25 mm lateral to the posterior border of sternocleidomastoid and 15 mm (one fingerbreadth) superior to the clavicle. This should be immediately posterolateral to the pulsation of the subclavian artery superior to the clavicle.
•
Raise a superficial weal of local anaesthetic at the needle insertion site with a 27G needle.
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Puncture the skin at the target point with a 25 mm to 50 mm nerve-block needle. Insert the needle perpendicularly to the skin and advance it 2 to 5 mm (
Fig. 8.9A&B). Redirect the needle inferiorly, keeping it parallel to the scalene muscles (in a slightly lateral direction) until paraesthesias are elicited. The insertion depth is unlikely to be more than 25 mm. Once the rib is contacted the needle can be ‘walked’ anteriorly and posteriorly while keeping the syringe parallel to the interscalene groove until the brachial plexus is located. If the rib is not found, the needle should be carefully redirected first laterally and then medially until it is contacted or paraesthesias or nerve twitches are elicited.
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If you are using a nerve stimulator, insert the needle using the same technique. The needle is advanced slowly until flexion or extension twitches of the fingers are obtained.
•
Aspirate. If no flashback of blood is obtained, inject 30 to 40 mL of local anaesthetic slowly with intermittent aspiration to rule out intravascular injection. Slow injection increases block success and decreases complications. If resistance to injection, severe paraesthesias or cramping pain sensations occur with initial injection, the needle should be withdrawn by 1 to 2 mm to avoid intraneural injection.
•
The onset of anaesthesia with lidocaine is from 5 to 15 minutes and with bupivacaine is from 10 to 20 minutes; duration of anaesthesia is 3 to 6 hours and 8 to 10 hours, respectively; duration of analgesia is 5 to 8 hours and 16 to 18 hours, respectively.
Precautions
This block is very safe if used appropriately and carefully. Avoid using this block in patients who have significant chronic respiratory disease or patients with respiratory distress, as well as in patients with contralateral phrenic nerve or recurrent laryngeal nerve paralysis.
Complications
Common side effects associated with this technique include phrenic nerve block with diaphragmatic paralysis and sympathetic nerve block with development of Horner’s syndrome. This usually only requires reassurance for the patient. Phrenic nerve block occurs in about 50% of cases and is not associated with respiratory dysfunction in healthy volunteers.
Pneumothorax associated with supraclavicular block is not common, is generally small requiring conservative treatment only, and develops within a few hours following the procedure. In rare instances its presentation can be delayed up to 12 hours.
Complications similar to those occurring with other peripheral blocks, such as intravascular injection with development of systemic local anaesthetic toxicity, as well as haematoma formation, may occur. Neurapraxias and neurologic injury are similarly possible, but rarely reported.
Ultrasound technique
This technique is a simple, easy-to-use method, does not require a nerve stimulator, and allows for smaller volumes of local anaesthetic to be used. It also virtually abolishes the likelihood of inadvertent vascular and pleural puncture.
Preparation
•
Position the patient supine or in semi-Fowler’s position with the head facing away from the side to be blocked.
•
Rest the arm comfortably by the patient’s side or across the abdomen.
•
Use a linear high-frequency probe (10 to 15 MHz is ideal) and select an appropriate pre-set application.
•
Identify the area to begin the scan – either the midline of the neck or the supraclavicular fossa.
•
Perform a preliminary non-sterile survey scan to identify the relevant anatomy and optimise the image by adjusting depth of field (20 to 30 mm), focus point, and gain. Mark the best probe position on the skin with a pen, if required. Position the probe over the supraclavicular fossa in the transverse plane to obtain the best possible cross-sectional view of the subclavian artery and brachial plexus (
Figs 8.10,
8.11A–C). Scan proximally and distally to observe the nerve roots and nerve trunks. The nerves in this region are round or oval, are hypoechoic, and can be found lateral and superficial to the subclavian artery (which can be identified with the assistance of colour Doppler if necessary) and superior to the first rib. The subclavian vein is medial to the artery. Visualise the pleura (check for the pleural sliding sign and comet tails) and note the relation to the brachial plexus and the planned needle track. Also take note of the distance from the skin to the rib and the skin-to-pleura distance.
•
Prepare the field by cleaning the skin with an antiseptic solution and positioning sterile drapes. Cover the probe with a sterile probe-sheath and apply sterile ultrasound gel to the area of the supraclavicular fossa.
Technique
In-plane approach (lateral to medial)
This approach is considerably different from the conventional supraclavicular techniques. The block needle is inserted in a very lateral position and advanced in a lateral to medial direction starting from the lateral edge of the probe. The in-plane approach enables the physician to track the needle tip in real time in order to minimise the risk of accidental pleural or vascular puncture.
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Identify the hypoechoic nerve roots in their transverse axis in the supraclavicular fossa.
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Raise a weal of local anaesthetic at the needle insertion target with a 27G needle.
•
Insert a 25 mm to 50 mm 22G nerve-block needle on the lateral end of the ultrasound probe.
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Advance the needle towards the edge of the nerve bundle while visualising the entire length of the needle in real time and avoiding pleural or vascular puncture (
Fig. 8.12).
An alternative in-plane approach (medial to lateral)
The advantage of ultrasound guidance is that any approach can be used and the needle tip can be positioned next to the nerves under direct vision (Fig. 8.13). While this approach has the advantage of advancing the needle away from the artery and the pleura, it also makes it more difficult to position the needle close to the nerves if they lie deep or directly lateral to the artery.
Out-of-plane approach
This is similar to the traditional blind landmark approach. The needle is introduced and advanced into the proximity of the nerve (Fig. 8.14).
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Identify the subclavian artery and the round hypoechoic nerve trunks of the brachial plexus located lateral to the artery, with the probe in the transverse plane in the supraclavicular fossa.
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Raise a weal of local anaesthetic with a 27G needle at the needle insertion point on the superior side of the transducer.
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Introduce a 25 mm to 50 mm 22G nerve-block needle perpendicular to the superior aspect of the probe.
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Advance the needle carefully towards the edge of the nerve trunks. While the needle itself might not be visible, its progress can be assessed by local tissue movement and the tip can be followed by angling the probe back and forth in order to avoid pleural or vascular puncture.
The injection process
•
Slowly inject local anaesthetic around the nerve roots by positioning the needle adjacent to the nerve sheath. Aspirate frequently to avoid inadvertent intravascular injection. If resistance to injection, severe paraesthesias or severe cramping pain are provoked in the limb during injection, immediately withdraw the needle by 1 to 2 mm to avoid intraneural injection.
•
Observe the local anaesthetic spread during injection. A hypoechoic collection will appear adjacent to and then spread around the nerves. If no fluid collection develops, then ensure that intravascular injection has not occurred.
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Observe the pattern of local anaesthetic spread around the target nerves during injection. Inject most of the local anaesthetic immediately superior to the first rib and next to the subclavian artery if anaesthesia to the distal forearm and hand is desired, because the ulnar nerve often lies in this position, posterior to the subclavian artery.
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Reposition the needle at least once to ensure complete circumferential local anaesthetic spread around the nerve roots.
Infraclavicular block
Landmark technique
The infraclavicular block is a blockade of the brachial plexus in the region of the coracoid process. This provides good anaesthesia for the hand, wrist, forearm, elbow, and distal arm, but is not a good choice for anaesthesia or analgesia for the shoulder, the axilla and the proximal medial arm. The coverage is similar to that of the supraclavicular block.
This block may be the one of most useful of the brachial plexus blocks in the acute trauma patient when there is limited access to the neck and it is an advantage not to have to move the limb to allow the block to be administered.
Preparation
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Position the patient supine with the head facing away from the side to be blocked.
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The arm can be kept at the patient’s side or across their abdomen, but ideally the arm should be abducted at the shoulder and flexed at the elbow to keep the relationship of the landmarks to the brachial plexus constant. Make sure that you can visualise the twitches of the hand.
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With a pen, mark the important landmarks for the infraclavicular block (
Fig. 8.15):
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The medial end of clavicle.
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The coracoid process – as the arm is elevated and lowered the coracoid process can be felt medial to the shoulder.
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The midpoint of a line connecting the medial end of clavicle and the coracoid.
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The needle insertion point – 30 mm inferior and perpendicular to the midpoint of the line between the medial end of the clavicle and the coracoid.
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For the mid-clavicular ‘vertical needle’ approach, mark the following landmarks (
Fig. 8.16):
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The jugular fossa (suprasternal fossa).
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The most anterior part of the acromion.
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The midpoint of a line connecting the jugular fossa and the acromion.
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The needle insertion point – immediately inferior to the clavicle at the midpoint of the line between the jugular fossa and the acromion. This should be exactly one fingerbreadth (10 mm) medial to the infraclavicular fossa.
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For the sub-coracoid ‘vertical needle’ approach, mark the following landmarks (
Fig. 8.17):
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A point 20 mm inferior and 20 mm medial to the coracoid process.
Technique
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Prepare the field by cleaning the skin with an antiseptic solution and positioning sterile drapes.
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Identify the target area for needle insertion – about 30 mm inferior to the midpoint of a line joining the medial end of the clavicle and the coracoid process.
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Raise a superficial weal of local anaesthetic at the needle insertion site with a 27G needle.
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