Supraclavicular block procedure guide

INTRODUCTION — The supraclavicular block anesthetizes the brachial plexus at the level of the trunks and divisions, and is used for surgery of the upper extremity. This topic will discuss the anatomy and injection techniques for supraclavicular block.

General considerations common to all peripheral nerve blocks, including patient preparation and monitoring, use of aseptic technique, localization techniques, drug choices, contraindications, and complications are discussed separately. (See "Overview of peripheral nerve blocks".)

Ultrasound guidance for peripheral nerve blocks is also discussed in detail separately. (See "Ultrasound for peripheral nerve blocks".)

ANATOMY — The brachial plexus is derived from the ventral rami of C5 to T1 spinal nerve roots and may also have variable contributions from both C4 and T2 nerve roots [1]. From roots, the brachial plexus then intricately converges and divides into trunks, divisions, cords, and branches to provide innervation to the entirety of the upper extremity.

●Course of the brachial plexus – In the supraclavicular region, the brachial plexus coalesces to form the superior (upper; C5-6), middle (C7), and inferior (lower; C8-T1) trunks. The plexus then travels between the posterior border of the sternocleidomastoid muscle and the anterior border of the trapezius muscle, reorganizes into divisions, and ultimately continues under the clavicle to become the cords. The trunks of the brachial plexus lie adjacent to the subclavian artery. The superior and middle trunks are located either superior or lateral to the subclavian artery and adopt a more lateral position as they course distally. The inferior trunk is located immediately lateral to the subclavian artery in the space often referred to as the "corner pocket" formed by the first rib and subclavian artery.

●Other nerves – Two clinically relevant nerves branch off of the brachial plexus at the level of the trunks.

•The suprascapular nerve most commonly branches off the superior trunk of the brachial plexus, with fibers derived primarily from the C5 and C6 nerve roots [2], and travels with the brachial plexus until ultimately separating off towards the shoulder. The suprascapular nerve runs along the lateral aspect of the brachial plexus in the supraclavicular region, just under the omohyoid muscle. (See 'Ultrasound guided technique' below.)

•The nerve to subclavius (also called the subclavius nerve) emerges from the superior trunk before traveling to the subclavius muscle and the clavicle (figure 1 and figure 2 and figure 3) [3].

●Blood vessels – Vascular structures in the region of the supraclavicular block and potentially in the needle path include the subclavian artery and vein, and the dorsal scapular, suprascapular, and transverse cervical arteries (figure 4).

●Pleura – The first rib and pleura lie just deep to the inferior trunk of the brachial plexus and the subclavian artery.

●Innervation – The brachial plexus trunks provide sensory and motor innervation of the entire upper extremity, often including the shoulder, with the exception of sensory block of the medial upper arm (intercostobrachial nerve, T2) and the cape of the shoulder which is innervated by C1 to C4 branches of the superficial cervical plexus [4]. The suprascapular nerve, which divides from the superior trunk, innervates the supraspinatus/infraspinatus muscles and acromioclavicular and glenohumeral joints.

The nerve to subclavius innervates the subclavius muscle and the periosteum of the clavicle.

Cutaneous sensory innervation is shown in a figure (figure 5). Motor innervation of the terminal nerves of the brachial plexus may be relevant for interpretation of nerve stimulation and is shown in a table (table 1).

CLINICAL IMPLICATIONS OF ANATOMY — Supraclavicular block may be used for analgesia or anesthesia for upper arm, including for surgery, trauma, chronic upper extremity pain, or vascular insufficiency. Use of supraclavicular block for orthopedic trauma and for vascular access for dialysis is discussed separately. (See "Anesthesia for orthopedic trauma", section on 'Anesthesia for upper extremity trauma' and "Arteriovenous fistula creation for hemodialysis and its complications", section on 'Anesthesia'.)

●Anesthesia or analgesia below the shoulder – For analgesia at or distal to the level of the mid humerus the supraclavicular block should provide analgesia or anesthesia equivalent to more distal brachial plexus blocks (ie, infraclavicular or axillary blocks). For medial forearm and hand procedures, it is particularly important to inject local anesthetic around the inferior trunk (ie, at the "corner pocket") to anesthetize the nerve fibers from the C8 to T1 nerve roots (figure 6) [5,6].

Like other brachial plexus blocks, an intercostobrachial block is required for anesthesia or analgesia of the upper arm proximal to the elbow (figure 7).

●Shoulder anesthesia and analgesia

•Supraclavicular block does not reliably provide complete surgical anesthesia for the shoulder because the suprascapular nerve (which innervates part of the shoulder) branches off the brachial plexus above the level of the block, as described above (figure 2). Thus, for complete shoulder anesthesia, an interscalene block would be required, or a suprascapular block could be performed in addition to supraclavicular block. This combination would reduce the incidence of phrenic nerve block, compared with interscalene block, but the incidence of phrenic nerve block is still substantial with supraclavicular block. This is discussed below. (See 'Phrenic nerve block' below.)

•Supraclavicular block may provide adequate, though not complete, analgesia after shoulder surgery or injury. The literature comparing supraclavicular block with interscalene block (ISB) for shoulder analgesia is conflicting, with some studies finding superiority of ISB, and others no differences regarding analgesia and phrenic nerve block. In a meta-analysis of trials comparing ISB with supraclavicular block for shoulder analgesia, 24 hour morphine consumption and pain scores were similar, and the incidence of respiratory dysfunction was lower after supraclavicular block [7]. Conclusions from this study are limited by high heterogeneity and small sample sizes.

ULTRASOUND GUIDANCE VERSUS NERVE STIMULATOR GUIDANCE — We suggest using ultrasound guidance whenever supraclavicular block is performed, rather than nerve stimulator guidance alone. Similar to performing other nerve blocks, we use ultrasound to identify the relevant structures, avoid blood vessels, visualize appropriate spread of local anesthetic, and in this case, to identify and avoid the pleura. Nerve stimulation may be used during ultrasound guided block to confirm correct position of the needle tip and to avoid intraneural injection. (See "Overview of peripheral nerve blocks", section on 'Block guidance techniques'.)

Ultrasound guidance may improve supraclavicular block efficacy, efficiency and speed of onset [8], and may theoretically reduce the incidence of pneumothorax [9], compared with the use of nerve stimulator guidance alone.

In a single institution trial, 80 patients who had supraclavicular block performed for distal arm or hand surgery were randomly assigned to block placement using ultrasound guidance with nerve stimulator confirmation, versus nerve stimulator guidance alone [8]. The addition of ultrasound guidance reduced the time to perform the block and resulted in a higher likelihood of complete block, particularly in the ulnar nerve territory. Successful surgical anesthesia and the need for general anesthesia were lower with ultrasound guidance, but the result was not statistically significant.

ULTRASOUND GUIDED TECHNIQUE

Single versus multiple injections — We suggest using a two-injection technique for supraclavicular block when the block is being used for surgical anesthesia, primarily to speed the onset of a complete block. We place one 10 to 15 mL injection of local anesthetic (LA) at the "corner pocket" formed by the subclavian artery, the first rib, and the brachial plexus, and another 10 mL at a more superficial location adjacent to the brachial plexus or, less commonly, among the nerves. This is the technique we describe here.

A single injection of 20 to 30 mL of LA at the "corner pocket" is a reasonable alternative, particularly if the block is intended to be used primarily for postoperative analgesia. A two-injection technique speeds the onset, which is important for surgical anesthesia but is not a concern for analgesic block. A single injection block saves time and reduces the amount of needle manipulation.

Studies comparing one versus two injections for supraclavicular block are conflicting with respect to onset time and block success.

●In one trial including 92 patients who were randomly assigned to single versus double injection supraclavicular block for anesthesia for surgery at or distal to the elbow, time to complete anesthesia was shorter with two injections (17.5 ± 8.4 versus 21.7 ± 7.2 minutes) [10]. Success rates for surgical anesthesia were similar in the two groups (>95 percent).

●In another trial, 100 patients who had supraclavicular block for anesthesia for hand, forearm, or elbow surgery were randomly assigned to one versus two injections for the block [11]. The rate of complete sensory block at 15 minutes was similar after single versus double injection block (49 versus 53 percent). The rate of complete surgical block at 30 minutes was higher after double injection (90 versus 76 percent), though this result was not statistically significant.

Performing the block

●Position the patient with the head rotated to the contralateral side. Some contributors to this topic have the patient sitting upright, with the ipsilateral arm pulled caudally to open the supraclavicular fossa and maximize visualization of the first rib and supraclavicular fossa. In patients with thick necks, place a pillow or blanket under the shoulders to extend the neck and improve visualization (figure 8).

●Select a linear high frequency transducer (eg, 15 to 5 mHz), with the depth set initially at 4 to 5 cm. (See "Ultrasound for peripheral nerve blocks", section on 'Transducers'.)

●Place the ultrasound transducer on the anterior neck immediately cephalad and parallel to the midpoint of the clavicle (figure 8).

●Scan as follows:

•Identify the subclavian artery, the first rib, and the pleura deep to it. Maintain visualization of the pleura throughout the block procedures. The pleura can be distinguished from the first rib by its deeper location and shimmering appearance resulting from the parietal and visceral pleura sliding against each other.

•Identify the brachial plexus immediately lateral to the subclavian artery (figure 8). The trunks and divisions of the brachial plexus appear as a group of hypoechoic round structures, sometimes referred to as a cluster of grapes, 1 to 3 cm deep to the skin.

•Tilt the ultrasound transducer cephalad and caudal to scan along the subclavian artery until the subclavian artery is visualized lying over the medial aspect of the rib while the brachial plexus lies over the lateral aspect of the rib.

•Rotate the ultrasound transducer slightly such that the lateral aspect of the transducer moves slightly cephalad, so the transducer is more perpendicular to the long axis of the subclavian artery and brachial plexus.

Note: The target for the first injection is the "corner pocket" formed by the subclavian artery, the first rib, and the brachial plexus.

•Identify the suprascapular nerve at the lateral aspect of the brachial plexus, beneath the omohyoid muscle.

●Slide the transducer as necessary to position the brachial plexus in the medial portion of the screen. This position will allow for a decreased angle of incidence, improved block needle visualization, and an enhanced ability to access the "corner pocket" formed by the subclavian artery and first rib.

●Use color Doppler to identify significant vasculature in the path of the block needle.

●For ultrasound guidance without nerve stimulator confirmation, insert a short bevel (30^°) 10 cm 21-gauge needle in-plane to the transducer (picture 1), 1 to 2 cm lateral to the lateral edge of the transducer, with a shallow insertion angle, visualizing the needle tip throughout.

●For nerve stimulation confirmation along with ultrasound guidance, set the stimulator to a pulse width of 100 ms at 2 Hz and an initial current of 1.0 mA. We use an insulated, 30° (short) bevel, 20- to 22-gauge 5 to 10 cm stimulating needle. Connect the nerve stimulator to the needle and to an electrode placed on the patient's skin.

●Advance the needle tip beneath the brachial plexus to the "corner pocket," avoiding the suprascapular nerve. Use hydrodissection with small volumes of saline or LA as necessary to create space for avoiding the nerves while advancing the needle.

●If nerve stimulation confirmation is used, look for a motor response in the arm below the shoulder. If stimulation occurs at 1.0 mA, reduce the current until it disappears, then turn it up to the minimal current that elicits a response. The goal is for a response at 0.2 to 0.5 mA. Adjust the needle tip as necessary.

●After negative aspiration, inject 1 to 2 mL of LA to visualize spread in the "corner pocket." Inject 10 to 15 mL of LA in 5 mL increments, with gentle aspiration between injections, while visualizing spread of LA around the brachial plexus. Reposition the needle as needed to optimize the spread of LA such that a pocket of LA separates the entire plexus from the first rib and lifts it off the rib. Stop injection and reposition the needle tip if the patient complains of pain or paresthesia, if there is resistance to injection, or if there are signs of intravascular injection (ie, lack of spread of LA, turbulent flow in a blood vessel). If using an injection pressure monitoring device, limit injection pressure to <15 pounds per square inch.

●Withdraw the needle to beyond the lateral edge of the brachial plexus, and angle the needle superficially, advancing to place the tip above or between the nerves of the brachial plexus. Adjust the needle tip as necessary to achieve spread of LA around the nerves.

●After negative aspiration, inject 1 to 2 mL of LA, visualizing spread around the trunks. Inject 10 to 15 mL of LA as described above.

DRUG CHOICES AND DOSING

Choice of local anesthetic — Local anesthetics (LAs) are selected according to the goal of the block (surgical anesthesia or analgesia) and the desired duration of the block. In general, longer duration LAs (eg, bupivacaine or ropivacaine) are appropriate for prolonged postoperative analgesia, whereas shorter duration LAs (eg, lidocaine or mepivacaine) may be more appropriate for procedures such as fracture reduction or wound suturing. More concentrated solutions (eg, 2% lidocaine, 1.5% mepivacaine, 0.5% bupivacaine or 0.75% ropivacaine) are used for surgical anesthesia and muscle relaxation, versus more dilute solutions (eg, 0.25% bupivacaine or ropivacaine) used primarily for analgesia.

It is important to consider the required and maximum allowable dose of LAs, patient comorbidities that might impact appropriate dosing (ie, hepatic or cardiac disease), and other potential sources of LA administration (ie, surgical infiltration). Patients should always be monitored during and after the block for signs and symptoms of local anesthetic toxicity (LAST), as LA doses within standard limits may still produce high systemic LA blood levels following supraclavicular blocks. In one observational study of 21 supraclavicular blocks performed with a 3:1 by volume mixture of 2% lidocaine with 0.5% bupivacaine, plasma lidocaine levels above the accepted toxic level occurred in one quarter of patients [12]. Bupivacaine levels were undetectable. There was no relationship between the total dose of lidocaine and plasma levels and the few patients who had mild symptoms of LAST did not have the highest blood levels of lidocaine. No patient had serious LAST. (See "Local anesthetic systemic toxicity" and "Local anesthetic systemic toxicity", section on 'Local anesthetic dose'.)

LAs for peripheral nerve blocks, including use of adjuvants, are discussed in more detail separately. (See "Overview of peripheral nerve blocks", section on 'Drugs'.)

Appropriate LA selection for supraclavicular blocks are as follows:

●Surgical anesthesia only – 2% lidocaine or 1.5% mepivacaine, which provide rapid onset, several hours of anesthesia, and limited postoperative analgesia.

●Postoperative analgesia – 0.25% bupivacaine or 0.2 to 0.5% ropivacaine. We often mix 0.5% ropivacaine with an equal volume of saline to create a 0.25% solution, which is not commercially available. These lower concentrations may provide effective analgesia with a decreased risk of LAST.

●Surgical anesthesia and postoperative analgesia, either:

•For rapid onset – Equal volumes of a short-acting LA (2% lidocaine or 1.5% mepivacaine) plus a long-acting LA (0.5% bupivacaine).

Note that mixing LAs usually results in onset and duration that are both intermediate between the two agents. (See "Clinical use of local anesthetics in anesthesia", section on 'Combinations of local anesthetics'.)

One randomized trial found that the combination of lidocaine with bupivacaine improved the success rate of relatively low volume block, compared with bupivacaine alone. Sixty three patients were randomly assigned to supraclavicular block with 20 mL of 2% lidocaine with epinephrine, 0.5% bupivacaine, or a 50:50 mixture of the two [13]. The percent of patients with a complete block at 40 minutes was similar after block with lidocaine or the combination, and both were higher than after bupivacaine alone (95 percent, 95 percent, and 48 percent, respectively). The combination produced block onset that was similar to lidocaine alone, and faster than bupivacaine alone. Duration of analgesia with the combination was longer than lidocaine but shorter than bupivacaine.

•When rapid onset is not required – 0.5% bupivacaine or 0.5% ropivacaine.

Volume of local anesthetic solution — The volume of LA required likely depends on a number of factors including patient size, indication for regional anesthesia technique, and brachial plexus localization technique. For most patients we use a total of 25 mL for the block, divided between the "corner pocket" and superficial injection. Several studies have evaluated the minimum effective volume of LA for supraclavicular block:

●Single injection block – In a single institution up and down sequential dosing study of 21 patients who had single injection ultrasound guided supraclavicular block for upper extremity surgery, the minimum effective injected volume of LA for complete block in 50 percent of patients was 23 mL, and for 95 percent of patients was 42 mL [14]. The block was performed with a 50:50 mixture of 2% lidocaine and 0.5% bupivacaine with epinephrine. The needle tip was inserted into the "corner pocket" (lateral to the subclavian artery, cephalad to the first rib) and in close proximity to the brachial plexus, with incremental injection and the needle repositioned only as necessary to visualize spread of LA around the nerves.

●Double injection block – In another single institution up and down sequential dosing study of 54 patients who had double injection ultrasound guided supraclavicular block for upper extremity surgery, the minimum effective volume of LA for complete block in 90 percent of patients was 32 mL (95% CI 30-34 mL) [15]. The block was performed with 1.5% lidocaine with epinephrine, with half the volume injected into the "corner pocket," and the remaining half injected in a more superficial location near the cluster of nerves.

Adjuncts — Adjuncts may be added to the LA solution to prolong the block or serve as a marker of intravascular injection. The author usually adds epinephrine to the block solution (100 mcg epinephrine in 30 mL LA; 3.3 mcg/mL). Another contributor occasionally uses dexamethasone to prolong the duration and improve the quality of the block.

In a network meta-analysis of 100 trials that investigated the use of perineural or intravenous dexamethasone or dexmedetomidine as adjuncts for supraclavicular block [16], sensory block duration was prolonged by perineural or intravenous dexamethasone and by perineural, but not intravenous dexmedetomidine. Mean duration of analgesia was approximately 6.7 hours in patients who received no adjunct, and was prolonged by approximately 8 hours with intravenous (IV) dexamethasone, 6.8 hours with perineural dexamethasone, and 4.7 hours with perineural dexmedetomidine. The quality of data was judged to be low or very low. Use of adjuncts for peripheral nerve blocks is discussed separately. (See "Overview of peripheral nerve blocks", section on 'Adjuvants'.)

CONTINUOUS SUPRACLAVICULAR BLOCK — A continuous supraclavicular block can be used to prolong analgesia beyond the duration of a single-shot block. Compared with other continuous brachial plexus blocks, advantages of supraclavicular block are the relatively shallow needle insertion angle, the ability to insert a catheter without the need for arm repositioning, and an insertion site that is easy to evaluate and monitor postoperatively (compared with axillary block). Continuous axillary block is rarely used because of relatively high risk of infection and the separation of the nerves at the level of the block, making coverage of multiple nerves with a single catheter challenging. (See "Axillary block procedure guide", section on 'Continuous axillary block'.)

Compared with continuous infraclavicular block, the supraclavicular approach may have a theoretical advantage due to the more compact nature of the brachial plexus at level of the block. Data comparing the two types of continuous block are limited. In one trial, 60 patients who had distal upper extremity surgery were randomly assigned to continuous supraclavicular versus infraclavicular blocks for postoperative pain [17]. Patients who had infraclavicular block had lower average pain scores on postoperative day one (median of 2 [10^th to 90^th percentile 0.5 to 6.0] versus 4 [10^th to 90^th percentile 0.6 to 7.7]), and used less oxycodone in the 18 to 24 hours after surgery (0 [10^th to 90^th percentile 0 to 5] versus 5 [10^th to 90^th percentile 0 to 15] mg). Conclusions are limited by high patient dropout rate and the per protocol (as opposed to intention to treat) analysis.

Catheter placement technique — The technique for continuous block is similar to single injection block (see 'Ultrasound guided technique' above). Technical aspects specific to continuous block are discussed here. (See 'Ultrasound guided technique' above.)

●We use a standard 19- or 20-gauge Tuohy needle with an epidural catheter for this technique. Both through the needle and over the needle specialized continuous block kits are available. Insulated, stimulating Tuohy needles and catheters are also available. (See "Overview of peripheral nerve blocks", section on 'Equipment'.)

●For ultrasound guided continuous blocks, an in-plane approach facilitates needle placement and visualization of appropriate catheter positioning and local anesthetic (LA) spread.

●Position the needle tip in the "corner pocket" between the subclavian artery, first rib, and trunks of the brachial plexus. If nerve stimulation confirmation is used, position the needle or catheter tip such that nerve stimulation produces a limited distal motor response at 0.2 to 0.5 mA.

●After negative aspiration for blood, inject a small volume of saline or LA to distend the space into which the catheter will be threaded and to verify adequate spread pattern with ultrasound.

Note: Nerve simulation confirmation will no longer be possible after injecting saline or LA around a stimulating needle tip or catheter. Injecting 5 percent dextrose in water (D5W) may maintain or even augment twitch responses and therefore may be considered in cases where hydrodissection is required to estimate needle position or clear a path to the desired needle tip location [18].

●Insert the catheter 2 to 4 cm beyond the tip of the needle. Visualize the catheter tip position near the nerve and withdraw the catheter as necessary to optimize spread of injectate near the plexus. Remove the needle without withdrawing the catheter.

●After negative aspiration, inject an epinephrine containing test dose (eg, 3 mL of 1.5% lidocaine with 5 mcg/mL [1:200,000] epinephrine) to assess for intravascular injection. (See "Overview of peripheral nerve blocks", section on 'Adjuvants'.)

●After a negative test dose, inject LA through the catheter as for single injection block.

Positioning, draping, and securing the catheter — Important technical aspects to consider when placing a catheter for continuous supraclavicular brachial plexus blocks include the following:

●Placing a perineural catheter takes longer than a single injection block and sufficient time must be allocated if placement is planned prior to a surgical procedure. Catheter placement time may be decreased as experience increases and with the use of catheter over needle techniques.

●A large sterile field should be created to avoid contamination of the catheter. We prefer to use towels rather than a plastic drape to reduce the risk that equipment slides off the sterile field.

●In addition to sterile gloves, mask, and cap, we wear a sterile gown to avoid contaminating the catheter during placement. A sterile ultrasound sheath must be used to avoid contamination of the sterile field.

●More liberal LA is usually required at the needle insertion site than for single injection block, since a larger needle is used for continuous block. In addition, immediately anesthetizing a track for catheter tunneling saves time later in the process. Slightly heavier sedation may also be necessary, though the patient should remain conscious enough to report a paresthesia or pain with injection through the needle or catheter.

●We tunnel the catheter away from the surgical site to decrease the rate of bacterial contamination, inadvertent dislodgement, and site leakage of LA [19]. Tunnelling may be particularly useful with supraclavicular blocks as the shallow catheter location may be more prone to site leakage and dislodgement of the occlusive dressing.

Infusion drug dose — After injecting a bolus of LA as described above for single injection block, the author initiates an infusion of LA at 5 to 12 mL/hour postoperatively, with a continuous or programmed intermittent bolus technique.

Specifics of our practice are as follows:

●For ambulatory patients with home-going catheters, the author initiates a continuous infusion of 0.2% ropivacaine. Prior to discharge, the patient and their caregiver receive a comprehensive instruction sheet that includes the signs and symptoms of LA toxicity, pump maintenance information, and the acute pain service phone number for any issues that may arise.

●For inpatients, the author generally uses 0.2% ropivacaine delivered via an intermittent programmed bolus infusion strategy. This intermittent infusion strategy may improve analgesia and reduce opioid requirements compared with continuous infusion [20].

●Maximum safe LA delivery doses should take into account all sources of LA administration (other blocks, LA infiltration) and patient factors that increase the risk of toxicity (eg, older age, hepatic insufficiency). (See "Local anesthetic systemic toxicity", section on 'Risk factors for LAST'.)

SIDE EFFECTS AND COMPLICATIONS — Supraclavicular brachial plexus blocks are generally safe. Complications common to all peripheral nerve blocks (eg, nerve injury, bleeding, local anesthetic systemic toxicity [LAST], infection) are discussed separately. (See "Overview of peripheral nerve blocks", section on 'Complications'.)

Several complications or side effects are more likely with supraclavicular blocks than with many other peripheral nerve blocks.

Pneumothorax — Pneumothorax is always possible during supraclavicular block, as the target for the block is just superficial to the first rib and the pleura beneath it. Prior to the widespread use of ultrasound guidance, use of supraclavicular block was limited by the risk of pneumothorax. Reported rates of pneumothorax with supraclavicular block were as high as 6.1 percent with landmark and paresthesia based techniques [21]. In contemporary practice, the incidence of pneumothorax is low [9]. One of the benefits of ultrasound guidance is the ability to visualize the needle tip and pleura throughout the block. However, nerve stimulator guidance may be associated with low risk of pneumothorax as well.

●In a single institution review of over 500 ultrasound guided supraclavicular blocks for upper extremity surgery, there were no clinically apparent cases of pneumothorax [22]. The blocks were performed with in-plane needle placement, and without specifically contacting the first rib.

●In a single institution retrospective review of 2000 nerve stimulator guided supraclavicular blocks for upper extremity surgery, there were no cases of pneumothorax [23].

●In a single institution prospective observational study of over 6300 ultrasound guided infraclavicular and supraclavicular blocks, the incidence of clinically evident pneumothorax was 0.06%; pneumothorax occurred only in blocks performed by clinicians with limited block experience (<20 procedures) [24].

Phrenic nerve block — Phrenic nerve block is a potential side effect of supraclavicular block, due to spread of local anesthetic (LA) to the phrenic nerve or to the C3 to C5 nerve roots. Thus, bilateral block should not be performed, and supraclavicular block should not be performed in patients with significant respiratory disease or known contralateral hemidiaphragmatic paralysis.

The reported incidence of symptomatic hemidiaphragmatic paralysis after supraclavicular block varies widely depending on the block technique and method used to assess diaphragm function [22,25-27]. Many patients without pulmonary disease are asymptomatic despite diaphragmatic paralysis.

●In one single institution study of ultrasound guided supraclavicular block using 30 mL of 0.5% bupivacaine, the incidence of hemidiaphragm paralysis at 30 minutes determined by lung ultrasound was 34 percent [25]. Approximately half of the patients with diaphragmatic paralysis complained of mild to moderate dyspnea.

●In the review of approximately 500 ultrasound guided blocks in patients without pre-existing pulmonary disease described above, there were 5 cases (1 percent) of symptomatic diaphragmatic paralysis [22]. The mean volume of LA injected was 33 ± 8 mL.

It may be possible to reduce the risk of phrenic nerve block by modifying the block technique. Use of low volumes of LA and single injection block in the "corner pocket" may result in a low incidence of phrenic block [22,27], but various techniques have not been compared head to head for this purpose, and using these techniques specifically to reduce the incidence of phrenic block is not supported by strong evidence.

Sympathetic block — Supraclavicular block can cause Horner's syndrome (ptosis and meiosis) as a result of block of the cervical sympathetic ganglion. Patients should be notified of the possibility of Horner's syndrome, as it can be misdiagnosed as a cerebrovascular event.

The reported incidence of Horner's syndrome after supraclavicular block varies widely. In the retrospective review of over 500 ultrasound guided blocks described above, Horner's syndrome occurred in 1 percent of patients. The mean LA volume used for the block was 33 mL [22]. By contrast, in a randomized trial that compared supraclavicular versus infraclavicular blocks in 120 patients, Horner's syndrome occurred in 29 percent of patients who had supraclavicular block [26]. The supraclavicular block protocol called for injecting 0.5 mL/kg of LA (minimum 30 mL, maximum 50 mL). The mean and range of volumes used were not reported.

Recurrent laryngeal nerve block — A supraclavicular block can rarely result in blockade of the ipsilateral recurrent laryngeal nerve and can result in hoarseness, and in the case of bilateral recurrent laryngeal block, airway obstruction. Thus, bilateral supraclavicular block should be avoided, and supraclavicular block should not be performed in patients with contralateral vocal cord paralysis or recurrent laryngeal nerve paralysis.

The incidence of recurrent laryngeal block after ultrasound guided block is unknown, but it is likely very rare. There are case reports of hoarseness after ultrasound guided block [28,29], however in the review of over 500 blocks discussed above, there were no reported cases of hoarseness after the block [22].

Recurrent laryngeal block may be more likely after right sided supraclavicular block than left because the course of the left nerve is usually more medial (away from the injection site). However, there are rare cases of left recurrent laryngeal aberrancy, and recurrent laryngeal block has been reported after left sided supraclavicular block [28,29].

Vascular puncture — Multiple arteries and veins are in the vicinity of the needle path and injection target during supraclavicular block. (See 'Anatomy' above.)

Thus, we use color Doppler to avoid vascular structures during the block. The incidence of inadvertent vascular puncture with ultrasound-guided supraclavicular blocks has been reported at 0.4% [22].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Local and regional anesthesia".)

SUMMARY AND RECOMMENDATIONS

●Anatomy – The brachial plexus is derived from the lower cervical and upper thoracic nerve roots (figure 1). The nerves of the brachial plexus travel through the neck, under the clavicle, and into the arm (figure 9). (See 'Anatomy' above.)

•The supraclavicular block targets the brachial plexus cephalad to the clavicle, at the level of the trunks and divisions (figure 2).

•It can be used for surgical anesthesia and analgesia for surgical procedures or injury of the upper extremity below the midhumerus, and for analgesia at the shoulder. The supraclavicular block alone does not provide complete anesthesia at the shoulder, as it does not anesthetize the suprascapular nerve.

●Ultrasound versus nerve stimulation guidance – We suggest using ultrasound guidance whenever supraclavicular block is performed, rather than nerve stimulator guidance alone (Grade 2C). We use ultrasound to identify the relevant structures, avoid blood vessels, visualize appropriate spread of local anesthetic (LA), and to identify and avoid the pleura. (See 'Ultrasound guidance versus nerve stimulator guidance' above.)

Nerve stimulator guidance can be used to confirm needle tip placement and avoid intraneural injection.

●Ultrasound-guided single injection supraclavicular nerve block – We perform supraclavicular block with ultrasound guidance as follows, with further explanation above. (See 'Performing the block' above.)

•Position the patient supine with the head rotated to the contralateral side.

•Use a high frequency transducer (eg, 15 to 5 mHz), with the depth set at approximately 3 cm, placed cephalad and parallel to the clavicle with the beam angled slightly caudally.

•Identify the first rib and pleura both medial and lateral to the rib.

•Identify the subclavian artery and brachial plexus where they are positioned just on top of the first rib. Maintain a view of the pleura throughout the block.

•Insert the needle in-plane to the transducer, visualizing the needle tip throughout and place the tip in the "corner pocket" formed by the junction of the first rib and the subclavian artery. After negative aspiration, inject 10 to 15 mL of LA.

•Reposition the needle more superficially above or between the nerves of the brachial plexus. After negative aspiration, inject 10 to 15 mL of LA, visualizing spread around the nerves.

●Continuous block technique – Continuous block is performed as described for single-injection block, using a Touhy needle with a 19- or 20-gauge catheter inserted through or a catheter-over-needle kit. (See 'Continuous supraclavicular block' above.)

●LA choice – The choice and concentration of LA is based on the goal for the block (ie, anesthesia versus analgesia), the desired duration of effect, other LA administered (eg, by the surgeon), and availability. (See 'Drug choices and dosing' above.)

•For single injection block

-For surgical anesthesia – 2% lidocaine, 0.5% bupivacaine, or 0.5% ropivacaine.

-For postoperative analgesia – 0.25% bupivacaine or 0.2 to 0.5% ropivacaine.

•For continuous block – Bolus injection as for single-injection block, followed by continuous infusion of 0.2% ropivacaine at 5 to 12 mL per hour with a programmed intermittent bolus technique. (See 'Infusion drug dose' above.)

●Side effects and complications – Potential adverse effects specific to supraclavicular block include the following (see 'Side effects and complications' above):

•Pneumothorax is always possible as the target for the block is just superficial to the first rib and the pleura beneath it. Thus, the pleura and needle tip should be visualized throughout the block procedures. (See 'Pneumothorax' above.)

•Phrenic nerve block results in hemidiaphragmatic paralysis and may occur in as many as one third of blocks. Supraclavicular block should be avoided in patients with significant respiratory compromise or known contralateral hemidiaphragmatic paralysis. (See 'Phrenic nerve block' above.)

•Horner's syndrome (ptosis and miosis) may occur in up to 30 percent of blocks and can be confused with a cerebrovascular event. Recurrent laryngeal nerve block and vocal cord paralysis can rarely occur. (See 'Sympathetic block' above and 'Recurrent laryngeal nerve block' above.)