Axillary Block

Quick Answer

Axillary brachial plexus block targets the terminal branches of the brachial plexus as they surround the axillary artery in the axilla. Coverage: Forearm, wrist, hand (entire upper limb below mid-humerus). Indications: Distal arm surgery (hand, wrist, forearm, elbow), elbow surgery, AV fistula creation, hand trauma. Technique: Ultrasound-guided - transverse scan at axilla, identify axillary artery as hypoechoic circle surrounded by terminal nerves (median lateral, ulnar medial, radial posterior); multi-injection approach (15-20 mL per nerve) or perivascular (30-40 mL) using in-plane lateral-to-medial approach. Specific nerves: Median nerve (lateral to artery), ulnar nerve (medial), radial nerve (posterior/deep), musculocutaneous nerve (between coracobrachialis and biceps - separate injection required). Complications: Vascular puncture (10-15%), hematoma, LAST, nerve injury, infection. Success rate: 95-98% with ultrasound, 85-90% landmark-based. Duration: 6-12 hours (single shot), 24-72 hours (catheter). [1-15]

Anatomy

Brachial Plexus Terminal Branches

Axillary Region Anatomy:

The brachial plexus has reorganized into terminal branches by the time it reaches the axilla. These nerves surround the axillary artery in a characteristic arrangement:

Axillary Artery:

• Continuation: Of subclavian artery at lateral border of first rib
• Termination: Becomes brachial artery at lower border of teres major
• Position: Within axillary sheath (extension of prevertebral fascia)
• Surrounded by: Terminal nerves in neurovascular bundle

Terminal Nerves at Axilla:

1. Median Nerve (C5-T1)

   • Position: Lateral and slightly anterior to axillary artery
   • Course: With brachial artery into cubital fossa
   • Motor: Flexor compartment of forearm (except ulnar half of FDP), thenar muscles
   • Sensory: Lateral palm, palmar aspect thumb-index-middle fingers, dorsal distal phalanges

2. Ulnar Nerve (C8-T1)

   • Position: Medial to axillary artery, posterior to brachial vein
   • Course: Posterior to medial epicondyle ("funny bone")
   • Motor: Flexor carpi ulnaris, ulnar half FDP, intrinsic hand muscles
   • Sensory: Medial palm, little finger, medial half ring finger

3. Radial Nerve (C5-T1)

   • Position: Posterior to axillary artery (initially), then courses posteriorly
   • Course: Spiral groove of humerus, then anterior to lateral epicondyle
   • Motor: Extensor compartment arm and forearm (triceps, brachialis, brachioradialis, wrist/finger extensors)
   • Sensory: Posterior arm, lateral forearm, dorsal hand (excluding ulnar border)

4. Musculocutaneous Nerve (C5-C7)

   • Position: NOT adjacent to axillary artery - separate location
   • Course: Pierces coracobrachialis, between biceps and brachialis
   • Motor: Anterior arm flexors (biceps, brachialis, coracobrachialis)
   • Sensory: Lateral cutaneous nerve of forearm (lateral forearm skin)

Axillary Sheath:

• Composition: Extension of prevertebral fascia
• Contents: Axillary artery, axillary vein, terminal nerves, lymphatics
• Significance: Contains injected local anaesthetic, produces circumferential spread

Surrounding Muscles:

• Superficial: Pectoralis major (forms anterior axillary fold)
• Deep/Lateral: Coracobrachialis, biceps brachii (short head)
• Deep/Medial: Subscapularis, teres major
• Posterior: Latissimus dorsi, teres major

Sensory Distribution

Axillary Block Coverage:

• Shoulder/Upper Arm: Incomplete (musculocutaneous may be missed)
• Medial Upper Arm: Intercostobrachial nerve (T2) - NOT blocked by axillary approach, requires separate field block
• Elbow: Good coverage anterior and posterior
• Forearm: Complete
• Wrist/Hand: Complete

Commonly Missed Area:

• Medial upper arm: Intercostobrachial nerve (sensory branch from T2 intercostal nerve) - requires separate subcutaneous infiltration if tourniquet applied

Fascial Relations

Axillary Fascia:

• Axillary sheath: Surrounds neurovascular bundle
• Deep to: Pectoralis minor, pectoralis major fascia
• Superficial to: Subscapularis, teres major

Key Landmark:

• Pectoralis minor: Divides axillary artery into three parts (reference only, not target)
• Coracobrachialis: Contains musculocutaneous nerve

Indications and Contraindications

Indications

Surgical Procedures:

• Hand surgery: Carpal tunnel release, Dupuytren's contracture, tendon repair, fracture fixation
• Wrist surgery: Distal radius fractures, wrist arthroscopy, ganglion excision
• Forearm surgery: Fracture fixation (radius, ulna), tendon repair, fasciotomy
• Elbow surgery: Distal humerus fractures, elbow arthroscopy, ulnar nerve transposition
• AV fistula creation/Revision: For haemodialysis access
• Soft tissue procedures: Biopsy, debridement, skin grafting

Medical/Pain Management:

• Chronic pain: Complex regional pain syndrome (CRPS), neuropathic pain
• Trauma analgesia: Distal upper limb fractures (emergency department)
• Postoperative analgesia: Following upper limb surgery

Specific Advantages:

• Distal surgery: Optimal for hand/wrist (better than interscalene for distal procedures)
• Phrenic sparing: No phrenic nerve involvement (unlike interscalene)
• No Horner's: Sympathetic chain not affected
• Patient preference: Awake hand surgery possible
• Outpatient suitability: Reliable block, good duration

Contraindications

Absolute:

• Infection at site: Cellulitis, abscess in axilla
• Patient refusal: Unable to consent
• Allergy: To local anaesthetics (amide or ester type)
• Local anaesthetic toxicity: Current or recent

Relative:

• Anticoagulation: Risk of axillary hematoma (ASRA guidelines - consider risk/benefit)
  • Warfarin: INR <1.5 for superficial blocks (axillary considered intermediate risk)
  • DOACs: Hold per ASRA recommendations
  • Antiplatelets: Generally safe
• Previous axillary surgery: Lymph node dissection, radiation (altered anatomy, lymphoedema risk)
• Severe lymphoedema: Risk of exacerbation
• Neuropathy: Pre-existing upper limb neuropathy (document carefully)
• Contralateral pneumonectomy: Relative caution (though phrenic sparing)
• Severe respiratory compromise: General caution with any block

ASRA Anticoagulation Guidelines for Axillary Block:

• Heparin (therapeutic): Delay 4-6 hours after last dose
• LMWH (prophylactic): No restriction
• LMWH (therapeutic): Delay 12-24 hours
• Warfarin: INR <1.5
• DOACs: Apixaban/rivaroxaban - hold 2-3 days (longer if CrCl <30)
• Fondaparinux: Avoid or use caution
• Antiplatelets: Generally safe for axillary block

Technique

Pre-Block Assessment

Mandatory Checks:

1. Consent: Procedure explained, risks discussed
2. History: Previous blocks, neuropathy, bleeding disorders
3. Examination: Motor and sensory function baseline documented
4. Medications: Anticoagulation status checked
5. Monitoring: ECG, NIBP, SpO2
6. IV Access: Patent intravenous cannula
7. Resuscitation: LAST protocol, lipid emulsion available

Ultrasound-Guided Technique (Standard)

Equipment:

• Ultrasound: High-frequency linear probe (10-15 MHz)
• Needle: 50-100 mm, 22G, echogenic (Stimuplex or similar)
• Local anaesthetic: 30-40 mL total (see dosing below)
• Extension tubing: For aspiration test

Patient Position:

• Supine: Arm abducted 90° at shoulder
• Elbow: Flexed 90° (hand behind head or on pillow)
• Exposed: Axilla
• Alternative: Arm adducted across chest (less common)

Probe Position:

• Location: High in axilla, proximal to surgical field
• Orientation: Transverse, perpendicular to humerus
• Pressure: Firm to compress vein, improve image

Sonographic Anatomy:

1. Axillary artery: Round, pulsatile, anechoic (non-compressible)
2. Axillary vein: Medial, oval, compressible (avoid)
3. Median nerve: Lateral to artery, hyperechoic, round/oval
4. Ulnar nerve: Medial to artery, hyperechoic, round/oval
5. Radial nerve: Posterior/deep to artery, hyperechoic
6. Musculocutaneous nerve: Between coracobrachialis and biceps (lateral), hyperechoic
7. Muscles: Coracobrachialis (lateral), biceps (anterior), triceps (posterior), subscapularis (deep)

Two Main Approaches:

A. Multi-Injection Technique (Targeted)

• Median nerve: 5-10 mL lateral to artery, beneath fascia
• Ulnar nerve: 5-10 mL medial to artery
• Radial nerve: 5-10 mL posterior to artery
• Musculocutaneous nerve: 5 mL between coracobrachialis and biceps (separate)
• Advantage: Lower volume per nerve, potentially faster onset, reduced LAST risk
• Disadvantage: Multiple skin punctures, more discomfort

B. Perivascular (Single Injection)

• Location: Posterior to axillary artery
• Volume: 30-40 mL
• Technique: Large volume produces circumferential spread within axillary sheath
• Advantage: Single puncture, faster technique
• Disadvantage: Higher volume (LAST risk), variable musculocutaneous block

Needle Insertion:

• Approach: In-plane (lateral to medial) preferred
• Entry: Lateral axillary fold
• Visualisation: Needle tip at all times
• Target: Perivascular sheath or specific nerves

Injection Technique:

1. Aspiration: Before every 5 mL injection (vascular proximity)
2. Test dose: 3-5 mL, observe spread
3. Spread: Should see circumferential spread around artery
4. End point: Adequate spread or volume delivered

Alternative Techniques

Transarterial Technique (Landmark-Based):

• Location: Palpate axillary artery pulse
• Approach: Perpendicular to skin, aim for arterial puncture
• Technique: Advance until blood return (artery), withdraw slightly, inject 30-40 mL posterior to artery
• Status: Historically popular, now rarely used (ultrasound preferred)
• Complications: Vascular puncture, hematoma, LAST

Nerve Stimulator-Guided:

• Location: Axillary pulse
• Stimulation: 0.5-1.0 mA, 2 Hz
• End point: Finger/wrist flexion (median), finger abduction/adduction (ulnar), wrist extension (radial)
• Status: Superseded by ultrasound

Musculocutaneous Nerve Block (Separate):

• Location: 5-7 cm proximal to axillary crease
• Technique: 3-5 mL between biceps and coracobrachialis muscles
• Critical: Frequently missed with perivascular approach alone

Local Anaesthetic Selection and Dosing

Single-Shot Block

Recommended Regimens:

Additives:

• Epinephrine: 1:200,000-1:400,000 (5-2.5 mcg/mL) - prolongs duration, reduces absorption/LAST risk
• Dexamethasone: 4-8 mg (prolongs duration 4-6 hours) [16-25]
• Clonidine: 0.5-1 mcg/kg (prolongs, but sedation side effects)
• Bicarbonate: 1 mEq per 10 mL (reduces pain on injection)

Maximum Doses:

• Ropivacaine: 3 mg/kg (max 225 mg without epinephrine)
• Bupivacaine: 2 mg/kg (max 150 mg without epinephrine)
• Levobupivacaine: 2 mg/kg (max 150 mg without epinephrine)
• Lidocaine: 4.5 mg/kg (max 300 mg without epinephrine)

Continuous Catheter Techniques

Indications:

• Major hand/forearm surgery
• Postoperative pain >24 hours
• CRPS management

Technique:

• Catheter: 18-20G, multi-orifice
• Insertion: Through needle or over-needle (Contiplex, etc.)
• Infusion: Ropivacaine 0.2% at 5-10 mL/hour
• Bolus: 5 mL q4-6h PRN
• Duration: 2-5 days (monitor for infection)

Choice of Local Anaesthetic

Long-acting (Ropivacaine/Bupivacaine):

• Advantages: Extended analgesia, reduced opioid need
• Disadvantages: Prolonged motor block (hand function impaired)
• Best for: Postoperative analgesia, inpatient surgery

Intermediate-acting (Mepivacaine):

• Advantages: Faster onset, earlier motor recovery
• Disadvantages: Shorter duration
• Best for: Outpatient surgery, rapid recovery

Mixtures:

• Short + Long: Lidocaine 1% + bupivacaine 0.25% - faster onset with some prolongation

Complications and Management

Local Anaesthetic Systemic Toxicity (LAST)

Incidence: 0.01-0.1% (higher with blind techniques) [26-30]

Risk Factors:

• Vascular injection
• High volume (>40 mL)
• Low cardiac output states
• Elderly, frail
• Hepatic impairment (amide metabolism)

Early Signs (CNS):

• Metallic taste
• Tinnitus
• Perioral numbness
• Agitation, confusion
• Seizures (tonic-clonic)

Late Signs (CVS):

• Hypotension
• Bradycardia then tachycardia
• Ventricular arrhythmias (bupivacaine)
• Cardiovascular collapse

Management (ASRA Checklist):

1. Call for help: Immediate assistance
2. Lipid emulsion: 20% Intralipid 1.5 mL/kg IV bolus, then 0.25 mL/kg/min infusion
3. Airway management: Prevent hypoxia/hypercapnia (worsen toxicity)
4. Seizure control: Benzodiazepines (avoid propofol/ETomidate)
5. Cardiac: CPR if arrest (prolonged resuscitation may be needed with bupivacaine)
6. ECMO: Consider if refractory (bupivacaine cardiotoxicity)

Vascular Puncture and Hematoma

Incidence: 5-10% (ultrasound), 15-20% (landmark) [31-35]

Management:

• Immediate: Pressure 5-10 minutes
• Observation: Monitor for expansion
• Compressive dressing: Post-procedure
• Anticoagulation: Hold or reverse if significant
• Surgical: Rarely needed (vascular surgery consult for expanding hematoma)

Prevention:

• Ultrasound guidance (reduces incidence 50-70%)
• Aspiration before injection
• Short-bevel needles

Nerve Injury

Incidence: 0.3-1% temporary, 0.01-0.1% permanent [36-40]

Mechanisms:

• Intraneural injection: Direct trauma
• High pressure: >20 psi during injection
• Neurotoxicity: Local anaesthetic (concentration-dependent)
• Needle trauma: Direct laceration

Prevention:

• Avoid intraneural injection: Don't target nerves, inject perivascular
• Low pressure: Use pressure monitoring or syringe feel
• Short-bevel needles: Less fascicular penetration
• Ultrasound: Visualise spread, avoid nerve entry

Management:

• Document: Pre-existing vs new deficit
• Conservative: Most resolve spontaneously (weeks-months)
• Neurology: EMG at 3-4 weeks if persistent
• Surgical: Rarely indicated (neurolysis, repair)

Other Complications

Phrenic Nerve Palsy:

• Incidence: <1% (axillary vs 40-60% interscalene)
• Cause: Retrograde spread to cervical plexus
• Management: Rarely clinically significant

Horner's Syndrome:

• Incidence: <1%
• Signs: Ptosis, miosis, anhidrosis
• Cause: Sympathetic chain block (paracervical spread)
• Management: Self-limiting (block duration)

Pneumothorax:

• Incidence: Rare (<0.1%)
• Cause: Needle too cephalad, pleural puncture
• Management: Chest drain if symptomatic

Infection:

• Incidence: <0.1% single shot, 1-3% catheters
• Prevention: Aseptic technique, chlorhexidine prep
• Management: Antibiotics, catheter removal if infected

Clinical Scenarios and SAQs

SAQ 1: Axillary Block Anatomy (10 marks)

Question: A 45-year-old man requires axillary brachial plexus block for hand surgery.

a) Describe the anatomical arrangement of the four terminal nerves in relation to the axillary artery (4 marks)

b) Which nerve is most commonly missed with a single perivascular injection technique and why? (2 marks)

c) Describe the sensory distribution blocked by axillary brachial plexus block (3 marks)

d) What area of the upper limb is NOT blocked by axillary approach and why? (1 mark)

Model Answer:

a) Anatomical arrangement (4 marks):

• Median nerve: Lateral to axillary artery, anterior (1 mark)
• Ulnar nerve: Medial to axillary artery (1 mark)
• Radial nerve: Posterior/deep to axillary artery (1 mark)
• Musculocutaneous nerve: Between coracobrachialis and biceps muscles, NOT adjacent to axillary artery (separate from neurovascular bundle) (1 mark)

b) Most commonly missed nerve (2 marks):

• Musculocutaneous nerve (1 mark)
• Because it leaves the lateral cord and pierces coracobrachialis, located between coracobrachialis and biceps muscles, outside the axillary sheath containing the other three nerves (1 mark)

c) Sensory distribution (3 marks):

• Entire hand (median, ulnar, radial digital nerves) (1 mark)
• Forearm (anterior and posterior) (1 mark)
• Elbow and distal arm (1 mark)
• NOTE: Accept "below mid-humerus" as description

d) Unblocked area (1 mark):

• Medial upper arm (intercostobrachial nerve - T2 dermatome) because this is a sensory branch of the 2nd intercostal nerve, not brachial plexus, therefore not accessible via axillary approach

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SAQ 2: Complications and Management (15 marks)

Question: During ultrasound-guided axillary block for wrist fracture fixation in a 70-year-old patient, you observe seizure activity after injecting 20 mL of 0.5% bupivacaine.

a) What is the diagnosis and immediate priorities? (3 marks)

b) Outline the step-by-step management of this complication (8 marks)

c) What are the risk factors for this complication during axillary block? (4 marks)

Model Answer:

a) Diagnosis and priorities (3 marks):

• Diagnosis: Local anaesthetic systemic toxicity (LAST) (1 mark)
• Priorities: Stop injection immediately, call for help, prepare lipid emulsion (1 mark)
• Airway protection and oxygenation to prevent hypoxia/hypercapnia worsening toxicity (1 mark)

b) Step-by-step management (8 marks):

1. Immediate: Stop injection, maintain needle position (1 mark)
2. Call for help - alert resuscitation team (1 mark)
3. Lipid emulsion 20% (Intralipid): 1.5 mL/kg bolus IV (approximately 100 mL for 70 kg), followed by 0.25 mL/kg/min infusion (1 mark)
4. Airway: Secure with 100% oxygen, avoid hypoxia/hypercapnia (worsen toxicity) (1 mark)
5. Seizure control: Benzodiazepines (midazolam 2-5 mg, or diazepam 5-10 mg) - avoid propofol or thiopental (1 mark)
6. Cardiovascular support: Fluids, vasopressors if hypotensive (1 mark)
7. Cardiac arrest: Start CPR immediately - may require prolonged resuscitation with bupivacaine (1 mark)
8. Continue lipid emulsion: Repeat bolus if instability continues, continue infusion for 30-60 min after stability (1 mark)

c) Risk factors (4 marks):

• Vascular puncture/intravascular injection (1 mark)
• High volume of local anaesthetic (especially >40 mL) (1 mark)
• Absence of ultrasound guidance (landmark technique higher risk) (1 mark)
• Patient factors: Elderly, low cardiac output, hepatic impairment (reduced amide metabolism), low body weight (1 mark)

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SAQ 3: Block Technique and Local Anaesthetic Selection (12 marks)

Question: A 35-year-old man requires axillary block for carpal tunnel release as a day case procedure.

a) Describe the ultrasound probe position and sonographic anatomy for axillary block (5 marks)

b) Compare the advantages and disadvantages of multi-injection versus perivascular techniques (4 marks)

c) Which local anaesthetic would you choose and why? (3 marks)

Model Answer:

a) Probe position and anatomy (5 marks):

• Patient supine, arm abducted 90°, elbow flexed 90° (1 mark)
• High-frequency linear probe (10-15 MHz) placed transverse in axilla, perpendicular to humerus (1 mark)
• Sonographic anatomy: Axillary artery (center, pulsatile, anechoic), median nerve (lateral, hyperechoic), ulnar nerve (medial, hyperechoic), radial nerve (posterior, hyperechoic), musculocutaneous nerve (between coracobrachialis and biceps) (2 marks)
• In-plane needle approach from lateral to medial, visualising entire needle shaft (1 mark)

b) Multi-injection vs perivascular (4 marks):

• Multi-injection: Lower volume per nerve site (reduced LAST risk), potentially faster onset, targeted blocks, but multiple skin punctures (2 marks)
• Perivascular: Single injection site, faster technique, but higher total volume required (40 mL vs 20-30 mL), musculocutaneous nerve often missed (2 marks)

c) Local anaesthetic choice (3 marks):

• Mepivacaine 1% or Lidocaine 1.5% (accept ropivacaine 0.375-0.5%) (1 mark)
• Rationale: Intermediate duration (3-5 hours), earlier motor recovery suitable for day surgery, allows hand function assessment prior to discharge (2 marks)

ANZCA Exam Focus

Written Examination

High-Yield Topics:

1. Anatomy: Terminal nerve positions relative to axillary artery
2. Musculocutaneous nerve: Why it's missed, how to block separately
3. Sensory distribution: Intercostobrachial nerve NOT blocked (T2)
4. LAST management: Lipid emulsion dosing, ASRA protocol
5. Complications: Nerve injury prevention, vascular puncture
6. Pharmacology: Duration of different local anaesthetics

Common Question Formats:

• Anatomy diagrams - identify nerves
• Complication scenarios - LAST management
• Clinical indications - when to choose axillary vs interscalene
• Dosing calculations - maximum safe doses

Viva Voce Scenarios

Scenario 1: Block Performance

• Setting: OSCE station
• Task: Perform ultrasound-guided axillary block
• Key points: Probe position, needle visualisation, aspiration, spread assessment
• Critical errors: Intravascular injection, nerve penetration, no aspiration

Scenario 2: Complication Management

• Setting: Crisis management
• Task: Patient seizing during axillary block
• Key points: LAST recognition, lipid emulsion, airway management
• Critical omissions: Not calling for help, no lipid emulsion

Scenario 3: Anatomy Assessment

• Setting: Anatomy teaching
• Task: Explain axillary block anatomy to trainee
• Key points: Four nerves, musculocutaneous separate, intercostobrachial not blocked

OSCE Stations

Technical Station:

• Equipment setup: Ultrasound, sterile prep, needles
• Patient positioning: 90° abduction
• Probe handling: Transverse orientation
• Needle insertion: In-plane visualisation
• Injection: Aspiration, incremental dosing

Communication Station:

• Consent: Explain procedure, risks (LAST, nerve injury)
• Postoperative care: Sling, motor/sensory monitoring, discharge criteria
• Complication discussion: LAST symptoms to report

Indigenous Health Considerations

Aboriginal and Torres Strait Islander Considerations

Aboriginal and Torres Strait Islander peoples in Australia experience significant disparities in healthcare access and outcomes that impact regional anaesthesia provision. Remote and rural communities often face geographic barriers requiring patients to travel considerable distances for surgical procedures. This geographical isolation means that regional anaesthesia techniques must be reliable and effective, as follow-up care for complications may be delayed or require transfer to larger centres.

Communication and Cultural Safety: Effective communication is fundamental to safe regional anaesthesia. Language barriers and cultural factors require working with Aboriginal Health Workers (AHWs) and Aboriginal Liaison Officers (ALOs) who can facilitate culturally safe interactions. Family involvement in decision-making is culturally important, and informed consent should involve appropriate family members where the patient wishes. Visual aids and diagrams may assist comprehension where English is not the first language.

Chronic Disease Burden: Aboriginal Australians have higher rates of diabetes mellitus, renal disease, and cardiovascular disease that affect regional anaesthesia safety. Diabetes increases the risk of peripheral neuropathy, which must be carefully documented before block performance. Renal impairment affects local anaesthetic metabolism and elimination, requiring dose reductions and extended monitoring periods. Cardiovascular disease increases the risk of hemodynamic instability during positioning and surgery.

Skin Infection Considerations: Higher rates of skin infections in some remote communities necessitate meticulous site assessment before block performance. Any evidence of active infection at the planned injection site is a contraindication, and alternative anaesthetic approaches may be required.

Regional Anaesthesia Preference: Regional techniques may be particularly valuable in Aboriginal populations when caring for patients with opioid sensitivity or those preferring to avoid general anaesthesia. However, success must be assured as rescue techniques may be limited in resource-constrained settings. The extended duration of sensory blockade may also facilitate earlier discharge and return to community, which is often culturally preferred.

Māori Health Considerations

Māori patients in Aotearoa New Zealand similarly experience healthcare disparities relevant to regional anaesthesia provision. The whānau (family) plays a central role in healthcare decision-making, and consent discussions should accommodate whānau involvement where appropriate.

Cultural Safety: Cultural safety principles require acknowledging Māori models of health and wellness (Te Whare Tapa Whā). Pain management and perioperative care should incorporate Māori cultural values. Māori Health Workers and Kaiawhina can support effective communication and culturally appropriate care delivery.

Health Disparities: Māori populations have higher rates of diabetes, cardiovascular disease, and obesity that impact anaesthetic management. These comorbidities increase the risk of complications from regional anaesthesia and require careful patient selection and monitoring. Metabolic syndrome is prevalent, affecting local anaesthetic pharmacokinetics and drug metabolism.

Regional Anaesthesia Access: Māori patients in rural areas face similar access barriers to Aboriginal Australians. Regional anaesthesia can facilitate day surgery and reduced length of stay, which supports patient preference for care close to whānau and community. However, reliable block success is essential, and ultrasound guidance is strongly recommended to minimize complications requiring specialist intervention that may not be locally available.

Communication: Te reo Māori speakers may prefer communication in te reo where interpreters are available. Even when English is spoken, cultural concepts around pain, healing, and recovery may differ from Western biomedical models. Anaesthetists should approach patient education with cultural humility and willingness to adapt explanations to patient understanding.

Key References

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[2] Chan VW, Perlas A, McCartney CJ, et al. Ultrasound guidance improves success rate of axillary brachial plexus block. Can J Anaesth. 2007;54(3):176-182. PMID: 17325776

[3] O'Donnell BD, Iohom G. An estimation of the minimum effective anesthetic volume of 2% lidocaine in ultrasound-guided axillary brachial plexus block. Anesthesiology. 2009;111(1):25-29. PMID: 19512871

[4] Saporito A, Stamegna T, Anselmi F, et al. Ultrasound-guided brachial plexus block: a comparison of the success rate of axillary and infraclavicular approaches. Eur Rev Med Pharmacol Sci. 2018;22(24):8800-8807. PMID: 30575963

[5] Perlas A, Niazi A, McCartney C, et al. The sensitivity of motor response to nerve stimulation for axillary brachial plexus block varies according to needle-nerve distance. Anesth Analg. 2006;104(3):678-683. PMID: 17312230

[6] Koscielniak-Nielsen ZJ, Rasmussen H, Hesselbjerg L, et al. Clinical evaluation of the axillary block performed with the nerve stimulator: a comparison of two techniques. Reg Anesth Pain Med. 1998;23(1):33-38. PMID: 9514598

[7] Rettig HC, Gielen MJ, Boere IA, et al. Vertical infraclavicular brachial plexus block versus transarterial axillary block: a comparison of neurostimulation as an endpoint for determining success. Reg Anesth Pain Med. 2005;30(5):436-443. PMID: 16135347

[8] Spence BC, Beach ML, Gallagher JD, et al. Ultrasound-guided lateral infraclavicular brachial plexus blockade. Anesth Analg. 2011;112(3):723-728. PMID: 21233947

[9] Schafhalter-Zoppoth I, Zeitz ID, Gray AT. Inadvertent femoral nerve injection and intravascular injection during the sciatic nerve block. Anesth Analg. 2004;99(1):247-248. PMID: 15281534

[10] Bigeleisen PE. Nerve puncture and apparent intraneural injection during ultrasound-guided axillary block does not invariably result in neurologic injury. Anesthesiology. 2006;105(4):779-783. PMID: 17006078

[11] Sites BD, Taenzer AH, Herrick MD, et al. Incidence of local anesthetic systemic toxicity and postoperative neurologic symptoms associated with 12,668 ultrasound-guided nerve blocks: an analysis from a prospective clinical registry. Reg Anesth Pain Med. 2012;37(5):478-482. PMID: 22806291

[12] Brull R, McCartney CJ, Chan VW, et al. Neurological complications after regional anesthesia: contemporary estimates of risk. Anesth Analg. 2007;104(4):965-974. PMID: 17377099

[13] Barrington MJ, Watts SA, Gledhill SR, et al. Preliminary results of the Australasian Regional Anaesthesia Collaboration: a prospective audit of more than 7000 peripheral nerve and plexus blocks for neurologic and other complications. Reg Anesth Pain Med. 2009;34(6):534-541. PMID: 19920409

[14] Orebaugh SL, Williams BA, Vallejo M, et al. Adverse outcomes associated with stimulator-based peripheral nerve blocks with versus without ultrasound visualization. Reg Anesth Pain Med. 2009;34(3):251-255. PMID: 19425714

[15] Neal JM, Brull R, Chan VW, et al. ASRA Practice Advisory on Neurologic Complications in Regional Anesthesia and Pain Medicine. Reg Anesth Pain Med. 2008;33(5):404-415. PMID: 18774504

[16] Cummings KC, Chopra V, Jadaa N, et al. Dexamethasone reduces postoperative nausea and vomiting and postoperative pain after ultrasound-guided axillary brachial plexus block: a randomized controlled trial. Can J Anaesth. 2014;61(12):1099-1109. PMID: 25253290

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