Brachial Plexus Blocks

Quick Answer

The brachial plexus (C5-T1 roots) provides motor and sensory innervation to the upper limb. Four principal approaches exist for brachial plexus blockade: interscalene (shoulder surgery, 100% phrenic nerve palsy), supraclavicular ("spinal of the arm" — forearm/hand, 0.5-1% pneumothorax risk), infraclavicular (hand/forearm, best catheter site), and axillary (distal upper limb, safest approach). Ultrasound guidance is now standard of care, with systematic reviews demonstrating 85-95% success rates compared to 60-70% for landmark-based techniques, alongside reduced local anaesthetic volumes (30-50% reduction) and complication rates. [1-3] Key complications include phrenic nerve block (interscalene contraindicated in severe respiratory disease), pneumothorax (supraclavicular), vascular puncture, and LAST. Local anaesthetic choice includes ropivacaine 0.5% or bupivacaine 0.25-0.5% (20-30 mL depending on approach), with perineural dexamethasone (4-8 mg) prolonging block duration by 4-8 hours. Block assessment utilises sensory testing in specific dermatomal distributions and motor function assessment. [4-6]

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Anatomy Overview

Brachial Plexus Formation: Roots, Trunks, Divisions, Cords, Branches

The brachial plexus is a somatic nerve plexus formed by the ventral rami of the lower four cervical nerves (C5-C8) and the first thoracic nerve (T1). Understanding its anatomical organisation is fundamental to successful regional blockade. [7,8]

Roots (C5-T1): The five roots emerge from the intervertebral foramina and pass between the anterior and middle scalene muscles in the posterior triangle of the neck. C5 and C6 roots emerge at the C6 vertebral level (cricoid cartilage landmark), while C7 emerges at C7 and C8/T1 at their respective levels. The roots lie deep to the prevertebral fascia and superficial to the transverse processes.

Anatomical relationships:

• Anterior: Sternocleidomastoid muscle, internal jugular vein
• Posterior: Middle scalene muscle, transverse processes
• Medial: Vertebral artery (caution during interscalene block)
• Lateral: Anterior scalene muscle

Trunks (Superior, Middle, Inferior): The roots combine to form three trunks in the supraclavicular fossa:

• Superior trunk: C5 + C6 (most accessible for interscalene block)
• Middle trunk: C7 alone
• Inferior trunk: C8 + T1 (lies closest to apex of lung)

The trunks cluster together in the supraclavicular region, creating the characteristic "bunch of grapes" ultrasound appearance. This compact arrangement makes the supraclavicular approach ideal for complete upper limb blockade.

Divisions (Anterior and Posterior): Each trunk divides into anterior and posterior divisions posterior to the clavicle. The anterior divisions supply flexor compartments; posterior divisions supply extensor compartments. These divisions are not clinically accessible as separate targets.

Cords (Lateral, Posterior, Medial): The divisions reform into three cords named by their relationship to the axillary artery in the infraclavicular region:

• Lateral cord: anterior divisions of superior + middle trunks
• Posterior cord: all three posterior divisions
• Medial cord: anterior division of inferior trunk

The cords wrap around the axillary artery beneath the pectoralis major and minor muscles, making them the target for infraclavicular blockade.

Terminal Branches: The five major terminal branches emerge from the cords:

Prefixed and Postfixed Plexus: Anatomical variations occur in 15-30% of patients:

• Prefixed plexus (C4-C8): More cephalad, may include C4 contribution
• Postfixed plexus (C6-T2): More caudad, T2 contribution present

These variations affect block distribution and may explain incomplete blocks despite technically correct injection. [9,10]

Dermatomal and Peripheral Nerve Distributions

Understanding both dermatomal (spinal nerve) and peripheral nerve distributions is essential for block assessment:

Cervical Dermatomes (Relevant to Brachial Plexus):

• C5: Lateral arm (deltoid region)
• C6: Lateral forearm, thumb, index finger
• C7: Middle finger, central palm
• C8: Medial forearm, ring and little fingers
• T1: Medial arm (axilla)
• T2: Medial upper arm (intercostobrachial — not blocked by brachial plexus)

Peripheral Nerve Cutaneous Distributions:

Motor Function Assessment:

• Shoulder abduction: Axillary nerve (C5-6)
• Elbow flexion: Musculocutaneous nerve (C5-6)
• Wrist extension: Radial nerve (C6-8)
• Finger flexion: Median nerve (C8-T1)
• Finger abduction: Ulnar nerve (C8-T1) [11,12]

Anatomical Considerations for Block Selection

Interscalene Level:

• Targets C5-C7 roots (superior and middle trunks)
• Spares C8-T1 (ulnar nerve territory) in up to 30% of cases
• Excellent for shoulder surgery
• Phrenic nerve (C3-5) runs on anterior scalene — blocked in 100% of cases

Supraclavicular Level:

• Trunks tightly clustered — "complete" upper limb block
• First rib posterior, subclavian artery deep, pleura inferior
• 0.5-1% pneumothorax risk with ultrasound guidance

Infraclavicular Level:

• Cords around axillary artery beneath pectoralis muscles
• Deep position — requires lower frequency probe in obese patients
• Excellent for catheter placement (secure fixation)
• Avoids phrenic nerve

Axillary Level:

• Terminal nerves (musculocutaneous, median, ulnar, radial)
• Musculocutaneous leaves plexus early — lies within coracobrachialis
• Safest approach (no pneumothorax, minimal phrenic risk)
• Multiple injections may be needed for complete coverage [13-15]

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Block Approaches

Interscalene Block

Indications:

• Shoulder surgery (rotator cuff repair, arthroplasty, arthroscopy)
• Proximal humerus surgery
• Clavicle surgery (lateral)
• Post-operative analgesia for shoulder procedures

Contraindications:

• Severe respiratory disease (FEV1 <40%, contralateral pneumonectomy)
• Contralateral phrenic nerve palsy
• Patient refusal
• Local infection
• Coagulopathy (relative)

Technique (Ultrasound-Guided):

1. Position: Supine, head turned 30-45° away, pillow under shoulders
2. Probe: High-frequency linear (12-15 MHz)
3. Scanning: Place probe in supraclavicular fossa, identify subclavian artery, scan cephalad to interscalene groove at C6 level
4. Target: Three hypoechoic nerve roots between anterior and middle scalene muscles ("traffic lights")
5. Needle: In-plane approach from lateral to medial
6. Injection: 10-20 mL local anaesthetic surrounding roots

Sonoanatomy:

• Anterior scalene muscle (anteromedial)
• Middle scalene muscle (posterolateral)
• Three roots appearing as hypoechoic circles ("traffic lights," "stacked coins")
• Vertebral artery deep to roots (use Doppler confirmation)
• Carotid sheath medially

Volume and Concentration:

• Standard: 15-20 mL 0.5% ropivacaine or 0.375-0.5% bupivacaine
• Low-volume technique: 5-10 mL (reduces phrenic nerve involvement to 30-40%)

Complications:

• Phrenic nerve palsy: 100% with standard volumes (25-30% FVC reduction)
• Horner syndrome: 40-60% (sympathetic chain involvement)
• Recurrent laryngeal nerve block: 5-10% (hoarseness)
• Vertebral artery injection (catastrophic)
• Epidural/intrathecal spread (rare, devastating)
• LAST

Evidence Base: A systematic review by Tran et al. (2016) demonstrated ultrasound-guided interscalene block achieves 95-98% success rates. The low-volume technique (5-10 mL) reduces hemidiaphragmatic paresis incidence while maintaining block quality. [16-18]

Supraclavicular Block

Indications:

• Elbow surgery
• Forearm surgery
• Wrist and hand surgery
• "Spinal anaesthesia of the arm" — blocks all trunks

Contraindications:

• Severe respiratory disease (pneumothorax risk + potential phrenic involvement)
• Contralateral pneumothorax or pneumonectomy
• Patient refusal
• Coagulopathy (relative)

Technique (Ultrasound-Guided):

1. Position: Supine, head turned away, arm at side
2. Probe: High-frequency linear (12-15 MHz)
3. Scanning: Place probe in supraclavicular fossa, parallel to clavicle
4. Target: "Bunch of grapes" cluster lateral and superficial to subclavian artery
5. Needle: In-plane from lateral to medial
6. Injection: 20-30 mL surrounding plexus, avoiding pleura and artery

Sonoanatomy:

• Subclavian artery (pulsatile, compressible)
• First rib (hyperechoic line with acoustic shadow posteriorly)
• Pleura (sliding lung sign, hyperechoic line with comet-tail artefacts)
• Brachial plexus trunks: hypoechoic "bunch of grapes" or "honeycomb"

Critical Safety Points:

• Always identify pleura before needle insertion
• Maintain needle tip visualisation throughout
• Never advance needle toward pleura
• "Corner pocket" injection between plexus and first rib

Volume and Concentration:

• Standard: 20-30 mL 0.5% ropivacaine or 0.375-0.5% bupivacaine
• Ultrasound-guided: 15-20 mL sufficient for complete block

Complications:

• Pneumothorax: 0.5-1% (ultrasound-guided), 3-5% (landmark)
• Phrenic nerve paresis: 50-67% (variable)
• Vascular puncture: Subclavian artery (1-5%), subclavian vein
• LAST
• Horner syndrome: 20-30%

Evidence Base: The supraclavicular block provides the most consistent and complete brachial plexus block due to the compact trunk arrangement. Ultrasound guidance has reduced pneumothorax rates from 3-6% to 0.5-1%. [19-21]

Infraclavicular Block

Indications:

• Hand and forearm surgery
• Elbow surgery (combined with intercostobrachial block for tourniquet)
• Continuous catheter placement (preferred site)
• Avoiding phrenic nerve involvement

Contraindications:

• Patient refusal
• Local infection
• Coagulopathy (deep structure, compression difficult)
• Pacemaker/ICD (relative — avoid probe pressure)

Technique (Ultrasound-Guided — Coracoid Approach):

1. Position: Supine, arm abducted 90° (pulls plexus caudad)
2. Probe: High-frequency linear (12-15 MHz) or low-frequency curvilinear for obese
3. Scanning: Place probe inferior and medial to coracoid process, sagittal plane
4. Target: Posterior cord (6 o'clock position relative to axillary artery)
5. Needle: In-plane from cephalad to caudad
6. Injection: 20-30 mL posterior to axillary artery

Sonoanatomy:

• Axillary artery (pulsatile) — central landmark
• Axillary vein (compressible, medial to artery)
• Cords: Lateral (9-12 o'clock), posterior (6 o'clock), medial (3-6 o'clock)
• Pectoralis major and minor muscles superficially
• Pleura deep (identify and avoid)

Needle Target: Single injection posterior to artery at 6 o'clock position produces circumferential spread around vessel, blocking all three cords simultaneously.

Volume and Concentration:

• Standard: 20-30 mL 0.5% ropivacaine or 0.375-0.5% bupivacaine
• Ultrasound-guided: 15-25 mL for complete block

Advantages:

• Lower phrenic nerve involvement than interscalene/supraclavicular
• Excellent for catheter placement (chest wall stabilises catheter)
• Complete coverage of terminal branches
• Lower pneumothorax risk than supraclavicular

Complications:

• Pneumothorax: 0.1-0.5% (rare but possible)
• Vascular puncture: Axillary artery/vein (2-5%)
• LAST
• Chest wall haematoma (difficult to compress) [22-24]

Axillary Block

Indications:

• Hand surgery
• Wrist surgery
• Forearm surgery (distal)
• Safest approach (no pneumothorax risk)

Contraindications:

• Patient unable to abduct arm
• Axillary lymphadenopathy
• Local infection
• Patient refusal

Technique (Ultrasound-Guided):

1. Position: Supine, arm abducted 90°, externally rotated, elbow flexed
2. Probe: High-frequency linear (12-15 MHz)
3. Scanning: Axillary crease, transverse to axillary artery
4. Target: Individual terminal nerves around axillary artery
5. Needle: In-plane from anterior

Sonoanatomy and Nerve Positions:

• Axillary artery (central landmark)
• Median nerve: 12 o'clock (often hyperechoic, oval)
• Ulnar nerve: 1-2 o'clock (medial)
• Radial nerve: 6 o'clock (posterior to artery)
• Musculocutaneous nerve: Separate, within coracobrachialis muscle (lateral)

Critical Point — Musculocutaneous Nerve: The musculocutaneous nerve exits the plexus early and travels within the coracobrachialis muscle. It must be blocked separately — failure to do so results in incomplete block of lateral forearm and weak elbow flexion.

Injection Strategy:

• Multi-injection technique: Block each nerve individually (5-7 mL each)
• Peri-arterial technique: Large volume (25-30 mL) around artery with separate musculocutaneous block
• Both techniques effective; multi-injection may provide faster onset

Volume and Concentration:

• Standard: 25-40 mL total (multi-injection: 5-7 mL per nerve)
• Concentration: 0.5% ropivacaine or 0.375-0.5% bupivacaine

Advantages:

• No pneumothorax risk
• No phrenic nerve involvement
• Superficial structures — excellent visualisation
• Compressible if vascular puncture occurs

Complications:

• Vascular puncture: 5-10% (compressible)
• Incomplete musculocutaneous block: 15-20% if not specifically targeted
• LAST
• Nerve injury (rare) [25,26]

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Ultrasound Guidance vs Nerve Stimulator

Comparison of Techniques

Evidence Base: A Cochrane systematic review (2019) demonstrated ultrasound guidance improves block success (RR 1.41, 95% CI 1.23-1.62), reduces procedure time, and decreases vascular puncture rates compared to nerve stimulation alone. [27,28]

When to Use Neurostimulation

Adjunct to Ultrasound:

• Confirmation of nerve identity in difficult anatomy
• Deep nerves with poor ultrasound visualisation
• Obese patients where ultrasound penetration is limited
• Teaching purposes

Neurostimulation Parameters:

• Current: 0.3-0.5 mA for proximity confirmation (avoid intraneural injection if response at <0.2 mA)
• Pulse width: 0.1 ms
• Frequency: 2 Hz
• Motor response should correlate with target nerve

Important Caveat: Nerve stimulation does not prevent intraneural injection. A motor response at low current (<0.2 mA) may indicate intraneural needle placement. Ultrasound allows direct visualisation of needle-nerve relationship and spread pattern.

Advantages of Ultrasound Guidance

1. Real-time visualisation of needle, nerve, and LA spread
2. Identification of anatomical variations
3. Vascular structure recognition (reduces puncture)
4. Confirmation of perineural spread
5. Dose reduction (30-50% less LA volume)
6. Reduced time to block onset
7. Improved patient safety [29]

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Local Anaesthetic Choice and Volumes

Recommended Local Anaesthetics for Brachial Plexus Blocks

Block-Specific Volumes

Adjuvants

Dexamethasone (4-8 mg perineural):

• Prolongs block duration by 4-8 hours
• Equivalent efficacy to IV dexamethasone (evidence equivocal)
• Reduces PONV
• No significant adverse effects at single doses

Clonidine (75-150 mcg perineural):

• Prolongs block duration by 2-4 hours
• May cause hypotension and sedation
• Less commonly used than dexamethasone

Epinephrine (1:200,000):

• Reduces peak plasma LA concentration
• Prolongs block duration modestly
• Intravascular injection marker (tachycardia)

Evidence: A meta-analysis by Pehora et al. (2017) confirmed perineural dexamethasone prolongs analgesia duration by a weighted mean difference of 6.7 hours (95% CI 5.5-7.8 hours) without increased complications. [30]

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Complications

Phrenic Nerve Block

Mechanism: The phrenic nerve (C3-5) descends on the anterior surface of the anterior scalene muscle. At the interscalene level, it lies immediately adjacent to the brachial plexus roots.

Incidence:

• Interscalene block: 100% (standard volume), 30-40% (low-volume 5-10 mL)
• Supraclavicular block: 50-67%
• Infraclavicular block: <5%
• Axillary block: 0%

Clinical Effects:

• 25-30% reduction in FVC and FEV1
• Diaphragmatic elevation on affected side
• Dyspnoea at rest in compromised patients
• Usually asymptomatic in healthy patients

Risk Factors for Symptomatic Paresis:

• Severe COPD (FEV1 <40% predicted)
• Contralateral phrenic nerve dysfunction
• Obesity (restrictive component)
• Sleep apnoea
• Neuromuscular disease

Prevention:

• Low-volume interscalene technique (5-10 mL)
• Extrafascial injection (outside interscalene sheath)
• Alternative blocks (infraclavicular, axillary) for respiratory-compromised patients
• Phrenic-sparing superior trunk block

Management:

• Reassurance (resolves with block wearing off)
• Supplemental oxygen
• Head-up positioning
• Rarely: Non-invasive ventilation for severe respiratory compromise

Pneumothorax

Mechanism: Direct needle puncture of pleura, most commonly during supraclavicular block where the lung apex lies immediately deep to the first rib.

Incidence:

• Supraclavicular (ultrasound): 0.5-1%
• Supraclavicular (landmark): 3-6%
• Infraclavicular: 0.1-0.5%
• Interscalene/Axillary: Extremely rare

Prevention:

• Always identify pleura on ultrasound before needle insertion
• Maintain needle tip visualisation throughout
• Avoid deep needle insertion beyond plexus
• Consider in-plane approach for better needle tracking

Presentation:

• May be immediate or delayed (up to 24 hours)
• Dyspnoea, pleuritic chest pain
• Reduced breath sounds, hyperresonance on affected side
• Oxygen desaturation

Management:

• If <15-20% and asymptomatic: Observation with serial CXR
• If >20% or symptomatic: Chest tube drainage
• Tension pneumothorax: Immediate decompression (needle then chest tube)

Vascular Puncture

Incidence:

• Ultrasound-guided: 0.5-2%
• Landmark-based: 5-10%

At-Risk Structures by Block:

• Interscalene: Vertebral artery, external jugular vein
• Supraclavicular: Subclavian artery/vein
• Infraclavicular: Axillary artery/vein
• Axillary: Axillary artery/vein

Prevention:

• Ultrasound visualisation of vessels
• Colour Doppler confirmation
• Aspiration before injection
• Avoid anticoagulated patients for deep blocks

Management:

• Immediate compression (where accessible)
• Observation for expanding haematoma
• Vascular surgery consultation if severe bleeding or pseudoaneurysm

Local Anaesthetic Systemic Toxicity (LAST)

Incidence: 0.03-0.1% for peripheral nerve blocks

Presentation:

• CNS prodrome: Perioral numbness, metallic taste, tinnitus, visual disturbances
• Seizures
• Cardiovascular collapse (may be first sign with bupivacaine)

Prevention:

• Maximum dose calculation
• Incremental injection (3-5 mL aliquots)
• Aspiration before and during injection
• Ultrasound guidance
• Lipid emulsion immediately available

Management (AAGBI/ASRA Protocol):

1. STOP injection, call for help
2. Airway management with 100% oxygen
3. Seizure control: Benzodiazepines (avoid propofol initially)
4. Lipid emulsion 20%: 1.5 mL/kg bolus, then 0.25 mL/kg/min infusion
5. Modified CPR if cardiac arrest (reduced epinephrine, prolonged resuscitation)

Nerve Injury

Incidence:

• Transient neuropathy: 1-5%
• Persistent deficit (>6 months): 0.02-0.04%

Mechanisms:

• Direct needle trauma
• Intraneural injection
• Local anaesthetic neurotoxicity
• Tourniquet injury (not block-related)
• Surgical positioning/traction

Prevention:

• Ultrasound guidance (avoid intraneural injection)
• Do not inject against high resistance (>20 psi)
• Avoid intraneural injection (nerve swelling on ultrasound)
• Neurostimulation response at >0.2 mA suggests extraneural position

Presentation:

• Numbness, paraesthesia, weakness persisting beyond expected block duration
• May be sensory, motor, or mixed

Management:

• Document neurological examination
• Reassurance if mild/resolving
• Neurology referral if persistent (>2 weeks)
• EMG/nerve conduction studies at 3-4 weeks
• Most resolve within 6-12 months [31,32]

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Block Assessment

Sensory Assessment

Test Points by Nerve:

Methods:

• Cold sensation (ice, alcohol swab)
• Sharp/dull discrimination
• Pinprick
• Light touch

Grading:

• 0: No sensation (complete block)
• 1: Reduced sensation (adequate block)
• 2: Normal sensation (inadequate block)

Motor Assessment

Timing of Assessment

• Initial assessment: 10-15 minutes post-block
• Reassess: 20-30 minutes (long-acting agents)
• Expected onset: 15-25 minutes (ropivacaine/bupivacaine)
• Complete block by: 30-45 minutes

Block Failure Management

Incomplete Block:

• Supplement with distal nerve blocks (e.g., ulnar nerve at wrist)
• Local infiltration at surgical site
• Convert to general anaesthesia

Complete Failure:

• Consider repeat block with different approach
• General anaesthesia

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Catheter Techniques

Indications for Continuous Catheter

• Major shoulder surgery (arthroplasty, major rotator cuff repair)
• Complex upper limb trauma
• Post-amputation stump pain
• Prolonged post-operative analgesia needs

Catheter Placement Sites

Preferred: Infraclavicular

• Stable catheter position (between chest wall and pectoralis)
• Lower dislodgement rate
• Minimal phrenic nerve involvement

Alternative: Interscalene

• Excellent for shoulder surgery
• Higher dislodgement rate (mobile neck)
• Phrenic nerve involvement (consider respiratory implications)

Technique

1. Perform standard block with catheter-introduction needle (17-18G Tuohy)
2. Confirm perineural position with local anaesthetic spread
3. Thread catheter 3-5 cm beyond needle tip
4. Secure catheter with transparent dressing and tunnelling if required
5. Connect to pump or patient-controlled bolus device

Infusion Protocols

Continuous Infusion:

• Ropivacaine 0.2%: 5-10 mL/hour
• Bupivacaine 0.125-0.25%: 5-8 mL/hour

Patient-Controlled Regional Analgesia (PCRA):

• Basal rate: 5 mL/hour
• Bolus: 3-5 mL
• Lockout: 20-30 minutes

Catheter Duration

• Typical: 48-72 hours
• Maximum: 5-7 days (increasing infection risk beyond 5 days)
• Remove when oral analgesia adequate

Complications

• Catheter dislodgement: 5-15%
• Infection: 1-3% (local cellulitis), <0.5% (abscess)
• Catheter kinking or occlusion
• Secondary block failure

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Special Populations

Respiratory Disease

Severe COPD (FEV1 <40%):

• Avoid standard interscalene block (100% phrenic paresis)
• Options:
  • Low-volume interscalene (5-10 mL) — 30-40% phrenic involvement
  • Infraclavicular or axillary block (no phrenic involvement)
  • Suprascapular + axillary nerve blocks for shoulder surgery
  • General anaesthesia with multimodal analgesia

Contralateral Pneumonectomy:

• Absolute contraindication to interscalene block
• Supraclavicular relatively contraindicated (pneumothorax + potential phrenic)
• Use infraclavicular or axillary approach

Anticoagulation

ASRA Guidelines (2018):

Risk Stratification:

• Superficial, compressible blocks (axillary): Lower risk
• Deep, non-compressible (infraclavicular, interscalene): Higher risk

Obesity

Challenges:

• Poor ultrasound penetration
• Difficult landmark identification
• Increased distance to plexus
• Higher LAST risk (relative overdose if based on total body weight)

Strategies:

• Lower frequency curvilinear probe (2-5 MHz) for deep structures
• In-plane needle approach for visualisation
• Longer needles (100-150 mm)
• Dose based on ideal body weight
• Ultrasound essential (landmark technique unreliable)

Paediatric Considerations

Dose Calculation:

• Bupivacaine: 2 mg/kg (max 2.5 mg/kg with epinephrine)
• Ropivacaine: 2.5-3 mg/kg
• Calculate carefully — lower therapeutic index in children

Technical Considerations:

• Higher frequency probes (15+ MHz) — structures more superficial
• Smaller volumes (0.3-0.5 mL/kg for most blocks)
• May require sedation or general anaesthesia for procedure

Elderly

Physiological Considerations:

• Reduced clearance of local anaesthetics (25-50% dose reduction)
• Increased sensitivity to neural blockade
• Pre-existing neuropathy more common (careful documentation pre-block)
• Higher cardiovascular disease prevalence (avoid LAST triggers)

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Indigenous Health Considerations

Regional anaesthesia for upper limb surgery in Aboriginal and Torres Strait Islander patients, as well as Maori patients in New Zealand, requires culturally safe approaches that acknowledge the specific health contexts and preferences of Indigenous populations.

Communication and Consent: Effective communication about brachial plexus blocks requires plain language explanations, often supported by visual aids and anatomical models. Many Aboriginal and Torres Strait Islander patients may prefer family members present during consent discussions, reflecting the collective decision-making approach valued in many Indigenous cultures. Aboriginal Health Workers (AHWs) and Aboriginal Hospital Liaison Officers (AHLOs) are valuable resources for facilitating these discussions and ensuring cultural safety. In New Zealand, involvement of whanau (extended family) in consent discussions aligns with tikanga Maori (cultural protocols).

Higher Prevalence of Comorbidities: Indigenous Australians have significantly higher rates of conditions that may affect brachial plexus block safety and efficacy:

• Diabetes mellitus (3-4 times non-Indigenous rates): May have pre-existing neuropathy requiring careful documentation and potentially increased susceptibility to nerve injury
• Chronic kidney disease: Altered drug handling, consider dose reduction
• Cardiovascular disease: Reduced cardiac reserve, increased LAST susceptibility
• Rheumatoid arthritis: Higher prevalence, may have cervical spine involvement affecting interscalene approach

These conditions warrant careful pre-procedure assessment, potentially reduced local anaesthetic doses, and enhanced monitoring.

Remote and Rural Access: Many Indigenous communities are located in remote areas where access to tertiary services is limited. Regional anaesthesia may be performed at rural hospitals with limited resources. Key considerations include:

• Ensure lipid emulsion availability before performing blocks
• Consider simpler, safer approaches (axillary over supraclavicular) when resources are limited
• RFDS retrieval services available for complications requiring higher-level care
• Telemedicine consultation can support remote clinicians

Cultural Protocols: If complications occur requiring resuscitation:

• Family presence during resuscitation may be culturally important — facilitate where possible
• Notification through AHLO if poor outcome
• Cultural protocols around the body vary between communities — consult with family and cultural advisors
• In New Zealand, karakia (prayer) before or after procedures may be requested by Maori patients

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ANZCA Final Exam Focus

Common SAQ Themes

Anatomy Questions:

• Describe the formation and course of the brachial plexus
• Outline the relevant anatomy for interscalene/supraclavicular block
• Describe the terminal branches and their functions

Technique Questions:

• Compare block approaches for specific surgeries
• Describe ultrasound-guided technique for specified block
• Discuss local anaesthetic choice and dosing

Complication Questions:

• Management of phrenic nerve palsy in respiratory-compromised patient
• Pneumothorax following supraclavicular block
• LAST management

Block Selection Scenarios:

• Shoulder surgery in COPD patient
• Upper limb surgery in anticoagulated patient
• Ambulatory hand surgery

Viva Themes

Clinical Reasoning:

• Block selection justification for specific clinical scenarios
• Risk-benefit discussions
• Alternative approaches when first choice contraindicated

Technical Expertise:

• Ultrasound probe selection and optimisation
• Needle approach selection
• Troubleshooting failed blocks

Complication Management:

• Real-time management of phrenic nerve compromise
• Pneumothorax recognition and management
• LAST recognition and treatment

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Assessment Content

SAQ Practice Question (20 marks)

Question: A 65-year-old male (75 kg) with severe COPD (FEV1 35% predicted, home oxygen 2 L/min) requires surgical repair of a rotator cuff tear. He refuses general anaesthesia.

(a) Discuss your regional anaesthesia options for this patient, including the risks and benefits of each approach. (10 marks)

(b) You decide to proceed with a phrenic-sparing block technique. Describe your technique, including ultrasound probe selection, sonoanatomy, needle approach, and local anaesthetic choice. (6 marks)

(c) Outline the post-procedure monitoring required for this patient. (4 marks)

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Model Answer:

(a) Regional Anaesthesia Options (10 marks)

Standard Interscalene Block — NOT RECOMMENDED [2 marks]

• 100% ipsilateral hemidiaphragmatic paresis with standard volumes
• 25-30% reduction in FVC and FEV1
• With FEV1 35% predicted, this reduction would likely cause significant respiratory compromise
• Contraindicated in this patient

Low-Volume Interscalene Block (5-10 mL) — POSSIBLE WITH CAUTION [2 marks]

• Reduces phrenic nerve involvement to 30-40%
• Still significant risk in severely compromised respiratory patient
• May not provide complete block for shoulder surgery

Phrenic-Sparing Techniques — PREFERRED [3 marks]

Superior Trunk Block:

• Targets C5-C6 contribution (shoulder innervation)
• Injection above C5-C6 trunk, away from phrenic nerve
• Reduces phrenic involvement to 10-20%
• Evidence: Tran et al. (PMID: 31548135) — 13% phrenic paresis vs 100% interscalene

Suprascapular + Axillary Nerve Block Combination:

• Suprascapular nerve: 70% shoulder sensory innervation
• Axillary nerve: Lateral shoulder (regimental badge)
• No phrenic involvement
• May be supplemented with superficial cervical plexus block
• Adequate for postoperative analgesia, may need supplementation for surgery

Infraclavicular Block — LIMITED UTILITY [1.5 marks]

• No phrenic involvement
• Does not provide adequate shoulder coverage (misses C5-C6 distribution)
• Not appropriate for shoulder surgery

General Considerations [1.5 marks]

• All techniques should be ultrasound-guided
• Local anaesthetic dosing: Use lowest effective dose
• Supplemental oxygen and monitoring essential
• ICU/HDU admission may be required post-operatively
• Consent must include discussion of respiratory risks

(b) Phrenic-Sparing Technique — Superior Trunk Block (6 marks)

Equipment [0.5 marks]

• High-frequency linear ultrasound probe (12-15 MHz)
• 22G, 50mm echogenic needle
• Ropivacaine 0.5% 8-10 mL (preferred for lower cardiotoxicity)

Patient Position [0.5 marks]

• Supine, head rotated 30-45° away from operative side
• Small pillow under shoulders

Scanning Technique [1.5 marks]

• Place probe in supraclavicular fossa
• Identify subclavian artery and brachial plexus
• Scan cephalad following plexus into interscalene groove
• Identify superior trunk (C5-C6) — most cephalad and posterior of the three roots
• Identify middle scalene posteriorly, anterior scalene anteriorly

Sonoanatomy Landmarks [1 mark]

• Superior trunk: hypoechoic oval structure, most lateral
• Phrenic nerve: On anterior surface of anterior scalene, anteromedial to plexus
• Aim to inject posterolateral to trunk, away from phrenic nerve

Needle Approach [1.5 marks]

• In-plane approach from lateral to medial
• Target: posterolateral aspect of superior trunk
• Avoid medial injection (phrenic nerve risk)
• Inject 8-10 mL ropivacaine 0.5%
• Observe spread around trunk, confirm avoiding phrenic nerve territory

Local Anaesthetic [1 mark]

• Ropivacaine 0.5% 8-10 mL (40-50 mg)
• Add dexamethasone 4 mg perineural if prolonged analgesia required
• Well below maximum dose (225 mg for 75 kg patient)

(c) Post-Procedure Monitoring (4 marks)

Respiratory Monitoring [2 marks]

• Continuous pulse oximetry for minimum 4-6 hours
• Respiratory rate monitoring
• Serial arterial blood gases if baseline hypercapnic
• Baseline and repeat spirometry (FVC, FEV1) at 30 minutes
• Maintain supplemental oxygen at usual rate or higher

Clinical Assessment [1 mark]

• Assess for dyspnoea, orthopnoea
• Auscultate for breath sounds bilaterally
• Watch for paradoxical breathing (diaphragmatic paralysis)
• Upright positioning preferred (optimises diaphragmatic function)

Location and Duration [1 mark]

• High dependency or monitored bed
• Minimum 12-24 hours observation
• Longer if any respiratory compromise develops
• Discharge criteria: SpO2 at baseline, no dyspnoea, adequate analgesia on oral medications

Total: 20 marks

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Viva Scenario (15 marks)

Opening Stem: You are the consultant anaesthetist called to recovery. A 45-year-old woman (60 kg) underwent left shoulder arthroscopy under interscalene block with 20 mL 0.5% ropivacaine. She is now complaining of severe breathlessness and has an oxygen saturation of 88% on room air.

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Expected Viva Progression:

Examiner: What are your differential diagnoses and initial assessment?

Candidate Response: [3 marks] "I'm concerned about several potential causes:

Primary concerns related to the block:

1. Hemidiaphragmatic paresis — expected with interscalene block, but may be symptomatic in susceptible patients
2. Pneumothorax — although interscalene has low risk, can occur with variant anatomy
3. High spinal/epidural spread — rare but catastrophic

Other considerations:

• Pulmonary embolism
• Bronchospasm/anaphylaxis
• Aspiration
• Cardiac event

My immediate actions:

• Apply high-flow oxygen (15 L/min via non-rebreather)
• Full monitoring: SpO2, ECG, NIBP
• Focused history: Onset of symptoms, any prodrome, previous respiratory disease
• Examination: Chest auscultation, respiratory pattern, tracheal position, JVP
• Review pre-operative respiratory function"

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Examiner: Examination reveals reduced breath sounds on the left with diaphragmatic paradox. No wheeze. What is your diagnosis and management?

Candidate Response: [4 marks] "The clinical picture — reduced left breath sounds with paradoxical diaphragmatic movement after interscalene block — is consistent with left hemidiaphragmatic paresis secondary to phrenic nerve block.

This is an expected complication of interscalene block (100% incidence with standard volumes), but this patient is unusually symptomatic.

I would:

Immediate Management:

• Continue high-flow oxygen to maintain SpO2 >92%
• Sit patient upright (30-45°) to optimize respiratory mechanics
• Provide reassurance — this will resolve as block wears off
• Check for any pre-existing respiratory disease not identified preoperatively

Further Assessment:

• Portable CXR to confirm elevated hemidiaphragm and exclude pneumothorax
• Blood gas if hypoxia persists despite oxygen
• Review pre-operative notes for respiratory history

If Hypoxia Persists:

• Consider NIV (CPAP/BiPAP) if severe
• Analgesia to optimize chest wall mechanics
• Bronchodilators if any reversible component
• Rarely: Consider admission to HDU/ICU"

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Examiner: CXR shows elevated left hemidiaphragm, no pneumothorax. Her SpO2 improves to 94% on 4 L/min oxygen. On further history, she reveals she has "mild asthma." How does this change your management?

Candidate Response: [4 marks] "The history of asthma, even if mild, explains her symptomatic response to hemidiaphragmatic paresis. Patients with underlying respiratory disease have less reserve to tolerate the 25-30% FVC reduction caused by phrenic nerve block.

This should have been identified pre-operatively.

Ongoing Management:

1. Continue supplemental oxygen — titrate to SpO2 94-98%
2. Bronchodilator therapy — salbutamol nebuliser 5 mg, ipratropium 500 mcg if needed
3. Position — keep upright
4. Observation — continuous SpO2 monitoring, serial respiratory assessments
5. Duration — symptoms should improve over 4-8 hours as ropivacaine effect wanes

Expected Timeline:

• Ropivacaine interscalene block duration: 8-12 hours with dexamethasone, shorter without
• Diaphragmatic function begins recovering at 4-6 hours
• Full recovery expected by 12-16 hours

Documentation:

• Document this complication and patient's respiratory history
• Flag for future anaesthetics — consider alternative regional techniques (infraclavicular, combined suprascapular + axillary nerve blocks)
• Explain to patient for future reference"

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Examiner: What would you do differently for future shoulder surgery in this patient?

Candidate Response: [4 marks] "For future shoulder surgery in this patient with asthma, I would:

Pre-operative Optimisation:

• Formal respiratory assessment (spirometry, baseline SpO2)
• Optimize asthma control pre-operatively
• Detailed informed consent including respiratory risks

Regional Anaesthesia Options:

Preferred: Phrenic-Sparing Techniques

1. Superior trunk block — targets C5-C6 with minimal phrenic involvement (10-20% vs 100%)
2. Suprascapular + axillary nerve block combination — no phrenic involvement, excellent shoulder analgesia
3. Low-volume interscalene (5-10 mL) — reduces phrenic involvement to 30-40%, still some risk

Alternative: General Anaesthesia with Regional Supplementation

• GA with suprascapular nerve block for postoperative analgesia
• Avoids phrenic nerve entirely
• May be preferred if patient very anxious about regional technique

Not Recommended:

• Standard interscalene block with 20 mL volume — too high risk in this patient

Post-Operative Planning:

• Plan for HDU/monitored bed regardless of technique
• Ensure respiratory support available
• Bronchodilators and supplemental oxygen readily available"

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Total: 15 marks

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