Supraclavicular Brachial Plexus Block

Quick Answer

Supraclavicular brachial plexus block targets the divisions of the brachial plexus where they pass over the first rib posterior to the subclavian artery at the level of the clavicle. Coverage: Complete arm anesthesia (C5-T1), including forearm and hand - most comprehensive upper extremity block. Indications: Elbow, forearm, wrist, hand surgery (ORIF, arthroscopy, amputation, finger procedures). Technique: Ultrasound-guided (essential - do not perform blind), visualize subclavian artery, first rib, pleura, and plexus "cluster" lateral and superficial to artery at rib level. Needle approach: Lateral to medial, in-plane, aim for corner pocket (lateral to artery, superficial to first rib), inject 20-30 mL LA. Complications: Pneumothorax 0.5-6% (classic risk), phrenic nerve palsy 40-60%, vascular puncture, LAST, Horner's syndrome. Safety improvements with ultrasound: Pneumothorax risk reduced to <0.5% (visualize pleura), more reliable block, less volume needed. [1-10]

Anatomy

Brachial Plexus at Supraclavicular Level

Location:

• Level: Divisions of brachial plexus (after trunks, before cords)
• Position: Posterior and lateral to subclavian artery, superior to first rib, inferior to clavicle
• Space: Interscalene groove continues, plexus now more compact

Key Structures (Ultrasound View):

1. Subclavian artery: Pulsatile, anechoic, non-compressible, most medial structure
2. Brachial plexus: "Cluster of grapes" appearance - multiple hypoechoic round/oval structures lateral and superficial to artery
3. First rib: Hyperechoic line with posterior shadowing deep to artery and plexus
4. Pleura: Hyperechoic line sliding with respiration, deep to first rib
5. Clavicle: Superior bony shadow
6. Subclavian vein: Medial to artery (often not visible in classic position)

Divisions Blocked:

• All three trunks/divisions: Superior (C5-C6), middle (C7), inferior (C8-T1)
• Result: Complete sensory and motor block of entire upper limb
• Ulnar distribution: Reliable (unlike interscalene which misses C8-T1)

Proximity to Lung:

• Pleura: 1-2 cm deep to first rib
• Risk: Pneumothorax if needle too deep (classic complication)
• Ultrasound: Visualize pleura, "pop" through fascia only until spread seen

Comparison with Other Brachial Plexus Blocks

Indications and Contraindications

Indications:

• Elbow surgery: ORIF distal humerus, elbow arthroscopy, replacement
• Forearm/wrist surgery: Radius/ulna fractures, wrist arthroscopy
• Hand surgery: Carpal tunnel, finger amputations, hand trauma
• Arteriovenous fistula creation: Vascular access surgery
• Catheter: Continuous infusion for major upper limb surgery

Contraindications:

Absolute:

• Contralateral phrenic nerve palsy (bilateral diaphragm paralysis)
• Severe respiratory disease with marginal reserve (COPD, FEV₁ <1L)
• Patient refusal
• Infection at site
• Anticoagulation (per ASRA guidelines - same as neuraxial)

Relative:

• Prior supraclavicular block on same side (risk cumulative phrenic palsy)
• Pre-existing hemidiaphragm paralysis
• Morbid obesity: Difficult ultrasound imaging
• Severe lung disease: Even unilateral phrenic palsy problematic
• Previous neck surgery: Altered anatomy
• COPD: Consider alternatives (axillary, infraclavicular)

Technique

Ultrasound-Guided Approach

Equipment:

• Ultrasound: High-frequency linear probe (10-15 MHz) OR curvilinear for larger patients
• Needle: 50-100 mm, 22G, echogenic
• Local anaesthetic: 20-30 mL (0.5% ropivacaine or 0.375-0.5% bupivacaine)

Patient Position:

• Supine: Head turned 30-45° away from block side
• Arm: Abducted 90° or at side
• Pillow under shoulders: Extends neck, improves access
• Trendelenburg: Helps venous engorgement, may improve view

Probe Position:

• Location: Just above clavicle, medial to SCM
• Orientation: Transverse (perpendicular to vessels)
• Sweep: Find subclavian artery, then look laterally for plexus

Sonographic Anatomy:

1. Identify subclavian artery: Pulsatile, anechoic (most medial)
2. First rib: Deep hyperechoic line with shadowing
3. Pleura: Deep to rib, sliding lung sign (CRITICAL TO IDENTIFY)
4. Brachial plexus: Lateral to artery, superficial to rib - cluster of hypoechoic circles
5. Muscles: Anterior and middle scalene muscles may be visible

Needle Insertion:

• Approach: In-plane (lateral to medial) - PREFERRED
  • Enter lateral to probe, aim medially toward plexus
  • Visualize entire needle shaft
• Alternative: Out-of-plane (cephalad to caudad)
  • More difficult, higher risk of pneumothorax
  • Not recommended for learning

Target: The "Corner Pocket"

• Location: Lateral to subclavian artery, superficial to first rib
• Space between: Artery and plexus
• Safe zone: Above rib, away from pleura
• Injection: See spread around plexus divisions

Injection Technique:

1. Aspiration: Before every injection
2. Test dose: 2-3 mL (watch for intravascular spread - arterial pulsation in fluid)
3. Inject: 20-30 mL in 5 mL aliquots
4. Watch for:
   • Spread around plexus (halo sign)
   • Local anesthetic tracking along rib
   • Pleura NOT touched (stays deep to rib)
5. Avoid: Deep to first rib (pneumothorax risk)

Volume:

• Standard: 20-30 mL
• Reduced with ultrasound: Some use 15-20 mL (better targeting)
• High volume: Better spread but higher LAST risk

Catheter Placement:

• Indication: Major surgery needing prolonged analgesia (elbow replacement, forearm fixation)
• Technique: Insert catheter 3-5 cm beyond needle tip
• Infusion: Ropivacaine 0.2% 5-8 mL/hour
• Secure: Well - catheter can migrate

Landmark Technique (Historical - Not Recommended)

Reasons to Avoid:

• High pneumothorax risk (6% in some series)
• Unreliable block
• Cannot see anatomy
• Unacceptable in modern practice

If used (rare circumstances):

• Plumb-bob technique: Midpoint clavicle, aim for sound of finger in suprasternal notch
• Subclavian perivascular: Artery as landmark
• Paresthesia method: Seek upper extremity paresthesia
• Nerve stimulator: Upper limb twitch

Modern standard: Ultrasound mandatory for safety

Complications

Pneumothorax

Incidence:

• Landmark technique: 0.5-6% (varies by operator experience)
• Ultrasound: <0.5% (most series <0.1%)

Mechanism:

• Needle through pleura into lung
• CO₂ absorption from pneumoperitoneum if laparoscopic
• Air enters pleural space

Presentation:

• Immediate: Cough, chest pain (rare - patient anaesthetized)
• Delayed: Desaturation, decreased breath sounds, respiratory distress
• Diagnosis: Ultrasound (loss of lung sliding), chest X-ray

Prevention:

• Ultrasound essential: Visualize pleura before needling
• Do not advance deep to first rib: Stay superficial to rib
• IPV: In-plane viewing of needle at all times
• Stop if: Patient becomes hypoxic, high airway pressures

Management:

• Small (<20%): Observation, O₂, serial imaging
• Symptomatic or large: Chest drain
• Postpone surgery: If significant, until resolved

Phrenic Nerve Palsy

Incidence: 40-60% (less than interscalene 100%, but still common)

Mechanism:

• C3-C5 roots close to injection
• Local anesthetic spread to phrenic nerve
• Hemidiaphragm paralysis

Clinical Effect:

• FVC reduction: 25-30%
• Usually asymptomatic in healthy patients
• Problematic in: COPD, obesity, contralateral phrenic palsy

Prevention:

• Cannot reliably prevent
• Lower volume may reduce incidence
• Consider alternatives if respiratory compromise

Management:

• Reassurance: Usually 12-24 hours duration
• Positioning: Semi-upright helps
• Avoid: Contralateral block

Vascular Complications

Subclavian Artery Puncture:

• Incidence: 1-5%
• Consequence: Hematoma, LAST if inject intravascular
• Prevention: Ultrasound, aspiration before injection, incremental dosing
• Management: Pressure, monitor for hematoma expansion

Local Anaesthetic Systemic Toxicity (LAST):

• Risk factors: High volume, intravascular injection, rapid injection
• Prevention:
  • Aspiration, incremental injection (5 mL aliquots)
  • Ultrasound (avoid intravascular)
  • Epinephrine marker (1:400,000 - detect IV spread)
• Management: Intralipid 20% emulsion (LAST protocol)

Other Complications

Horner's Syndrome:

• Incidence: 10-20%
• Signs: Ptosis, miosis, anhidrosis, nasal congestion
• Mechanism: Stellate ganglion block
• Duration: Until block resolves (12-24 hours)
• Benign: Reassure patient

Recurrent Laryngeal Nerve Block:

• Incidence: 5-10%
• Signs: Hoarseness
• Risk: Aspiration if severe

Neural Injury:

• Incidence: <0.1% permanent, 0.5-1% temporary
• Mechanism: Intraneural injection, trauma, hematoma compression
• Prevention:
  • Avoid intraneural injection (do not inject if high resistance, severe paresthesia)
  • Ultrasound guidance
  • Patient awake or lightly sedated (warn of paresthesia)
• Management: Follow-up, rehabilitation, rarely surgical exploration

Total Spinal/Epidural:

• Rare: Needle through neural foramen into epidural/subarachnoid space
• Presentation: Bilateral block, lower extremity involvement, cardiovascular collapse
• Management: Supportive (airway, fluids, vasopressors)

Clinical Management

Preoperative

Assessment:

• Respiratory: FEV₁, exercise tolerance, room air SpO₂
• Previous blocks: Document side, any complications
• Airway: If GA also planned
• Anticoagulation: Per ASRA guidelines

Informed Consent:

• Expected: Arm numbness and weakness (complete)
• Complications: Pneumothorax (rare with ultrasound), phrenic palsy (common), Horner's, hoarseness
• Duration: 12-24 hours (may need sling for protection)

Intraoperative

Sedation:

• Light: Midazolam 1-2 mg, fentanyl 50-100 μg
• Position: Comfortable, neck extended
• Communication: Warn patient about paresthesia (stop if severe pain)

After Block:

• Wait: 20-30 minutes for full effect
• Test: Sensory (pinprick in all distributions), motor (hand grip, wrist flexion/extension)
• Supplement: Individual nerves if incomplete (ulnar at elbow, median at wrist)

Combination with GA:

• Common for longer/complex procedures
• LMA or ETT
• Block provides analgesia, reduces opioid needs

Postoperative

Monitoring:

• Sensory: All dermatomes (C5-T1)
• Motor: Hand intrinsics, wrist flexors/extensors
• Respiratory: SpO₂, dyspnea (phrenic palsy)

Analgesia:

• Excellent: Usually sole analgesic or minimal opioids needed
• Plan: Paracetamol, NSAIDs if appropriate
• Rescue: Oxycodone if severe pain (breakthrough)

Arm Protection:

• Sling: Protect insensate, immobile arm
• Pressure areas: Check regularly (no sensation)
• Elevation: Reduce swelling

Catheter Management (if used):

• Infusion: Ropivacaine 0.2% 5-8 mL/hour + PCA bolus option
• Monitoring: Block level, motor function
• Duration: 2-3 days typically
• Removal: When oral analgesia adequate

Specific Procedures

Elbow Surgery:

• Perfect indication: Supraclavicular provides complete coverage
• Duration: Often 2-4 hours (block adequate)
• Catheter: Consider for major elbow replacement

Wrist/Hand Surgery:

• Excellent coverage: Includes median, ulnar, radial nerves
• Tourniquet: Well-tolerated (block covers arm)
• Day surgery: Common (carpal tunnel, trigger finger)

Forearm Fractures:

• Emergency: Can be done in ED for analgesia
• Surgical: Definitive fixation under block ± GA

Indigenous Health Considerations

Aboriginal and Torres Strait Islander Patients

Access Issues:

• Regional centers: May lack ultrasound expertise
• Trauma: Higher rates in some communities (require expert blocks)

Cultural Considerations:

• Communication: Explain what to expect (complete arm numbness)
• Sling use: Ensure understanding of protection needed
• Follow-up: Access to care if complications

Māori Health Considerations

Health Needs:

• Access to regional anaesthesia services
• Cultural safety in block procedures
• Family support during recovery

ANZCA Final Exam Focus

Key Points

1. Anatomy: Divisions of brachial plexus lateral to subclavian artery, over first rib
2. Coverage: Complete arm (C5-T1) - most comprehensive upper limb block
3. Pneumothorax risk: 0.5-6% landmark, <0.5% ultrasound (visualize pleura!)
4. Phrenic palsy: 40-60% (less than interscalene, still significant)
5. Target: "Corner pocket" - lateral to artery, superficial to rib
6. Contraindications: Contralateral phrenic palsy, severe respiratory disease
7. Volume: 20-30 mL LA
8. Catheter: Excellent for continuous analgesia
9. Safety: Ultrasound mandatory - do not perform blind
10. Superior to interscalene: For forearm/hand (includes ulnar)

References

1. Neal JM et al. Upper extremity regional anesthesia. Reg Anesth Pain Med. 2020;45(11):911-935.
2. Kapral S et al. Ultrasound-guided supraclavicular block. Reg Anesth Pain Med. 1994;19(1):36-39.
3. Williams SR et al. Ultrasound guidance speeds execution and improves quality of supraclavicular block. Anesth Analg. 2003;97(5):1518-1523.
4. Riazi S et al. Phrenic nerve palsy and regional anesthesia. Reg Anesth Pain Med. 2018;43(3):260-267.
5. Perlas A et al. Sonography and the risk of pneumothorax. Reg Anesth Pain Med. 2014;39(6):538-542.
6. Barrington MJ et al. Ultrasound-guided regional anesthesia. Reg Anesth Pain Med. 2014;39(6):508-521.
7. Liu J et al. Incidence of pneumothorax in ultrasound-guided supraclavicular block. Reg Anesth Pain Med. 2016;41(5):577-581.
8. Tran DQ et al. A comparison of ultrasound-guided versus landmark-based techniques. Reg Anesth Pain Med. 2009;34(4):335-339.