Environmental Medicine - Australia

Quick Answer

One-liner: Australian envenomation requires rapid identification, specific first aid (Pressure Immobilisation Bandage for snakes and funnel-webs), targeted antivenom therapy, and awareness of Indigenous and remote/rural health disparities.

Australian environmental emergencies involve venomous snakes, spiders, and marine creatures unique to our region. Snake envenomation causes Venom-Induced Consumption Coagulopathy (VICC), neurotoxicity, and myotoxicity. Funnel-web spider bites are life-threatening emergencies requiring immediate antivenom. Redback spider bites cause severe pain but are rarely fatal (antivenom now second-line). Marine envenomation ranges from box jellyfish (cardiotoxic, potentially fatal) to Irukandji syndrome (delayed severe hypertension, cardiac effects) and blue-ringed octopus (tetrodotoxin, respiratory paralysis). Pressure Immobilisation Bandage is critical for snakes and funnel-webs, while hot water immersion relieves marine stinger pain. Antivenoms are available for all high-risk Australian creatures but should be used judiciously based on clinical indications. Indigenous Australians face disproportionately higher envenomation rates due to geographic exposure and healthcare access barriers.

---

ACEM Exam Focus

Primary Exam Relevance

• Anatomy: Distribution of Australian venomous snakes by region; lymphatic anatomy (basis for Pressure Immobilisation Bandage)
• Physiology: Venom mechanisms (procoagulant toxins causing VICC, tetrodotoxin blocking sodium channels, delta-atracotoxin cholinergic crisis)
• Pharmacology: Antivenom pharmacokinetics (IgG vs IgM), adrenaline pretreatment, venom half-life, analgesia for envenomation

Fellowship Exam Relevance

• Written: High-yield topics include snakebite VICC management, antivenom selection, RAVE trial findings for redback spiders, first aid protocols
• OSCE: Likely scenarios include snakebite with coagulopathy, funnel-web envenomation with pulmonary oedema, marine stinger management, patient education on prevention
• Key domains tested: Medical Expert (diagnosis, management), Health Advocate (Indigenous health disparities, prevention, rural access)

Recent exam trends: Increased emphasis on evidence-based antivenom use (ASP studies), Indigenous health considerations, remote/rural management challenges, and environmental prevention strategies.

---

Key Points

---

Epidemiology

Australian/NZ Specific

Snakebite hotspots:

• Northern Territory: 50-70% of hospital admissions are Aboriginal patients [8] PMID: 28874402
• Queensland: Highest number of snakebites (30-35% of national total) [9] PMID: 23507088
• Western Australia: High incidence of brown snake envenomation [10] PMID: 27780223

Seasonal patterns:

• Box jellyfish: October to May (stinger season) [11] PMID: 22683676
• Snakes: Spring to early summer (October-December) [12] PMID: 23507088
• Irukandji: November to May (Northern waters) [13] PMID: 27454103

Indigenous population burden:

• Aboriginal and Torres Strait Islander peoples: 2-3× higher snakebite incidence [14] PMID: 28874402
• Māori: 2× higher marine envenomation rates in NZ coastal areas [15] PMID: 33726720
• Remote communities: 60-80% of snakebites involve "unknown" snake species [16] PMID: 28874402

---

Pathophysiology

Snake Venom Mechanisms

Venom-Induced Consumption Coagulopathy (VICC)

• Prothrombin activators: Factor Xa-Va complex (brown snakes, taipans) → massive thrombin generation
• Consumption: Fibrinogen, Factor V, Factor VIII depletion
• Laboratory: INR greater than 3, fibrinogen undetectable (below 0.5 g/L), D-dimer markedly elevated
• Time course: Coagulopathy complete within 1-2 hours; recovery 12-48 hours after antivenom [17] PMID: 28874402

Neurotoxicity

• Presynaptic (Taipan, Tiger snake): Irreversible damage to nerve terminal; recovery requires new synapse formation (days-weeks)
• Postsynaptic (Death adder): Competitive blockade at neuromuscular junction; potentially reversible with antivenom [18] PMID: 23343894

Myotoxicity

• Rhabdomyolysis: Skeletal muscle membrane damage → CK elevation (can exceed 100,000 IU/L)
• Mechanism: Phospholipase A2 activity (Tiger, Mulga, Sea snakes) → myoglobinuria → acute kidney injury [19] PMID: 23343894

Spider Venom Mechanisms

Funnel-Web Spider (delta-atracotoxin)

• Cholinergic crisis: Massive acetylcholine and catecholamine release
• Pulmonary oedema: Non-cardiogenic pulmonary oedema from increased capillary permeability and hypertension [20] PMID: 15996534
• Autonomic storm: Profuse sweating, salivation, lacrimation, piloerection

Redback Spider (alpha-latrotoxin)

• Neurotransmitter release: Massive release of acetylcholine, noradrenaline, and substance P
• Pain: Local and regional pain from substance P and CGRP
• Systemic effects: Tachycardia, hypertension, sweating (adrenergic surge) [21] PMID: 24680547

Marine Venom Mechanisms

Box Jellyfish (Chironex fleckeri)

• Pore-forming toxins: Cardiotoxin creates pores in cardiac myocyte membranes → rapid cardiovascular collapse
• Dermonecrosis: Painful local tissue necrosis from proteolytic enzymes [22] PMID: 22683676

Irukandji Syndrome (Carukia barnesi)

• Catecholamine surge: Massive sympathetic activation → severe hypertension, tachycardia
• Cardiac effects: Catecholamine-induced cardiomyopathy (Takotsubo-like) → acute pulmonary oedema [23] PMID: 27454103

Blue-Ringed Octopus (Tetrodotoxin)

• Sodium channel blockade: Prevents action potential generation in nerves and muscles
• Clinical: Conscious but fully paralysed, respiratory failure within minutes
• Recovery: Metabolized over 4-8 hours; complete recovery with ventilation [24] PMID: 25456328

Why It Matters Clinically

• VICC timing: Antivenom must be given early to prevent coagulopathy; once established, antivenom only prevents further consumption
• PIB mechanism: Venom travels via lymphatics; PIB slows lymphatic flow to systemic circulation (extends time window from below 30 minutes to greater than 6 hours) [25] PMID: 23507088
• Antivenom pharmacokinetics: IgG antivenoms have long half-life (3-5 days) but must neutralize circulating venom before tissue damage occurs
• Neurotoxicity distinction: Presynaptic neurotoxicity is irreversible (requires supportive ventilation), postsynaptic may respond to antivenom

---

Clinical Approach

Recognition

Key Historical Features

High-Risk Presentations (Immediate Action Required)

Initial Assessment

Primary Survey (Time-Critical Envenomations)

• A: Airway - Neurotoxicity (snakebite, blue-ringed octopus) → prepare for intubation
• B: Breathing - Pulmonary oedema (funnel-web, Irukandji) → oxygen, monitor
• C: Circulation - Cardiac arrest (box jellyfish), hypotension/hypertension (funnel-web, Irukandji)
• D: Disability - Neurotoxicity assessment (ptosis, diplopia, weakness)
• E: Exposure - Remove clothing, examine for bite marks, tentacle tracks

History

Key Questions for Snakebite

Key Questions for Marine Stingers

Red Flag Symptoms

Examination

General Inspection

• Vital signs: Tachycardia (redback, Irukandji), hypertension (funnel-web, Irukandji), hypotension (shock, box jellyfish)
• Skin: Fang marks, local swelling, necrosis, tentacle tracks, bruising (coagulopathy)
• Mental state: Anxiety, confusion (neurotoxicity, Irukandji)

Specific Findings

---

Investigations

Immediate (Resus Bay)

Standard ED Workup

Advanced/Specialist

Point-of-Care Ultrasound

Lung ultrasound (funnel-web, Irukandji):

• B-lines: Pulmonary oedema (interstitial fluid)
• Pleural effusion: Rare but possible

Cardiac ultrasound (box jellyfish, Irukandji):

• Reduced ejection fraction: Cardiomyopathy
• Wall motion abnormalities: Takotsubo-like pattern (Irukandji)

Soft tissue ultrasound (snakebite, spider bite):

• Local swelling, haematomas
• Foreign body (tentacle fragments)

---

Management

Immediate Management (First 10 Minutes)

Snakebite

1. KEEP PRESSURE IMMOBILISATION BANDAGE IN PLACE (DO NOT REMOVE)
2. ABC assessment, establish IV access (2 large bore)
3. Send urgent coagulation profile (INR, fibrinogen, D-dimer)
4. Monitor for neurotoxicity (ptosis, diplopia, bulbar weakness)
5. Prepare antivenom (adrenaline 0.25 mg IM pretreatment if needed)
6. Remove PIB ONLY when antivenom available and patient prepared

Funnel-Web Spider

1. KEEP PRESSURE IMMOBILISATION BANDAGE IN PLACE
2. IV access, cardiac monitoring
3. IMMEDIATE antivenom (2 vials IV) if systemic signs
4. Atropine 0.6 mg IV if profuse secretions
5. Prepare for intubation (pulmonary oedema risk)
6. Remove PIB after antivenom administered

Box Jellyfish

1. Remove patient from water immediately
2. Pour vinegar liberally over sting site (30+ seconds)
3. Remove tentacles with gloves/forceps
4. ABC assessment, cardiac monitoring
5. Administer Box Jellyfish Antivenom (3 vials IV) if collapse/arrhythmia
6. Supportive care (may need prolonged CPR greater than 1 hour)

Irukandji Syndrome

1. Vinegar first aid (if applicable)
2. Urgent transport to hospital (delayed systemic symptoms)
3. Analgesia: IV fentanyl (titrated to effect)
4. Magnesium sulphate 1-2 g IV (controversial, may reduce pain/hypertension)
5. GTN patch or infusion for severe hypertension
6. Monitor for cardiac failure (troponin, echo)

Blue-Ringed Octopus

1. Pressure immobilisation bandage
2. ABC assessment
3. Prepare for intubation and ventilation
4. Supportive care only (no antivenom)
5. Ventilation until toxin metabolized (4-8 hours)
6. Patient remains fully conscious throughout

Resuscitation (if applicable)

Airway

• Neurotoxic snakebite: Early intubation if bulbar weakness, respiratory compromise
• Funnel-web spider: Intubation for pulmonary oedema (hypoxia despite oxygen)
• Blue-ringed octopus: Immediate airway protection for respiratory paralysis
• Irukandji: Intubation for pulmonary oedema

Breathing

• Oxygen targets: SpO2 92-96% (box jellyfish, pulmonary oedema)
• Ventilation settings: Standard for neurological injury (low tidal volume 6 mL/kg)
• Non-invasive ventilation: May be appropriate for mild pulmonary oedema

Circulation

• Fluids: Crystalloid resuscitation for shock (avoid fluid overload in pulmonary oedema)
• Vasopressors: Noradrenaline for refractory hypotension (box jellyfish)
• Antihypertensives: GTN or phentolamine for Irukandji hypertension
• Antivenom: Specific therapy (see below)

Medications

Snake Antivenom

Administration:

• Pretreatment: Adrenaline 0.25 mg IM (0.1 mg for children below 25 kg) if history of antivenom reaction or atopy
• Dilution: Dilute in 500 mL normal saline (or 100-200 mL if severe envenomation)
• Rate: Infuse over 15-30 minutes (slower if reaction occurs)
• Repeat: Repeat every 15-30 minutes if ongoing envenomation (clinical improvement not achieved)
• Monitoring: Continuous cardiac and respiratory monitoring during infusion

Spider Antivenom

Funnel-web administration:

• Give immediately if systemic signs (fasciculations, sweating, hypertension)
• Repeat every 15 minutes if symptoms persist
• No pretreatment required (life-threatening emergency takes precedence)

Redback administration (RAVE trial evidence):

• NOT routinely indicated for local pain
• Consider ONLY for severe refractory systemic latrodectism not responding to analgesia
• IM or IV route (IV preferred for severe envenomation)
• Risk of anaphylaxis (0.5-1%) must be weighed against limited benefit [26] PMID: 24680547

Marine Antivenom

Analgesia

Adjunctive Medications

Paediatric Dosing

Ongoing Management

Snakebite Monitoring

• Coagulation profile: Every 6 hours until INR below 1.5, fibrinogen greater than 1.5 g/L
• Neurological assessment: Hourly for first 6 hours (ptosis, respiratory function)
• CK: Every 6-12 hours if myotoxicity suspected
• Observe minimum: 24 hours (brown/tiger), 48 hours (taipan, neurotoxicity)

Funnel-Web Monitoring

• Cardiac monitoring: Continuous for 4-6 hours post-antivenom
• Respiratory: SpO2, respiratory rate, pulmonary oedema signs
• Neurological: Fasciculations, muscle spasms
• Observe minimum: 12-24 hours depending on severity

Irukandji Monitoring

• Blood pressure: Every 15-30 minutes initially (severe hypertension risk)
• Cardiac: Troponin at 0, 6, 12 hours; echo if elevated
• Pain: Titrate analgesia to comfort
• Observe minimum: 12-24 hours

Definitive Care

ICU Admission Criteria

• Funnel-web spider with pulmonary oedema
• Irukandji with hypertension greater than 200/120 or cardiac failure
• Snakebite with intracranial haemorrhage
• Neurotoxic snakebite requiring ventilation
• Box jellyfish cardiac arrest survivor

Specialist Consultation

• Toxicologist: For complex envenomations, antivenom decisions
• ICU: For cardiac/respiratory support
• Cardiologist: For box jellyfish or Irukandji cardiac involvement
• Neurologist: For intracranial haemorrhage (VICC)
• Nephrologist: For acute kidney injury (myotoxicity, VICC-associated TMA)

Retrieval Considerations

• RFDS: 1800 625 800 for remote/rural envenomation requiring transfer
• Transfer criteria: Severe envenomation requiring antivenom not available locally, ICU requirement
• Pre-transfer stabilization: Ensure PIB in place, antivenom if indicated, airway secured

---

Disposition

Admission Criteria

• Snakebite: ALL suspected envenomations require admission (minimum 24-48 hours)
• Funnel-web spider: ALL bites (even if asymptomatic initially) - observation 12-24 hours
• Box jellyfish: ALL significant stings (observation for delayed cardiac effects)
• Irukandji: ALL cases (delayed symptoms - observation 12-24 hours)
• Blue-ringed octopus: ALL bites (respiratory support until recovery)

ICU/HDU Criteria

• Pulmonary oedema (funnel-web, Irukandji)
• Intracranial haemorrhage (VICC)
• Respiratory failure requiring ventilation (neurotoxicity, blue-ringed octopus)
• Severe cardiac involvement (box jellyfish, Irukandji)
• Multi-organ failure

Discharge Criteria

Important Note: Snakebite discharge:

• No evidence of envenomation (normal coagulation, no neurotoxicity) AND
• PIB removed in hospital with observation for 6 hours AND
• No bite witnessed (dry bite) OR
• Negative VDK AND asymptomatic for 24 hours

Funnel-web discharge:

• No systemic symptoms AND
• PIB removed with observation for 6-12 hours AND
• Normal cardiac monitoring

Redback spider discharge:

• Pain controlled with oral analgesia AND
• No systemic symptoms OR
• Systemic symptoms resolved

Marine stingers discharge:

• Pain resolved AND
• No cardiac symptoms (box jellyfish, Irukandji) AND
• Observation period complete (4-6 hours for bluebottle, 12-24 hours for Irukandji)

Follow-up

• GP letter: Detail envenomation, antivenom given, monitoring required
• Specialist referral: Nephrology (persistent AKI), Cardiology (persistent cardiac dysfunction), Neurology (residual deficits)
• Antivenom reaction counseling: Inform patient of delayed serum sickness risk (7-14 days)
• Psychological support: Trauma counseling for severe envenomations, especially cardiac arrest survivors

---

Special Populations

Paediatric Considerations

• Antivenom dosing: Children receive same adult dose (same venom load)
• Respiratory failure: Children have smaller respiratory reserve → lower threshold for intubation
• Volume status: Children more prone to dehydration with vomiting → fluid replacement
• Discharge criteria: More cautious observation required (higher risk of delayed envenomation)

Pregnancy

• Antivenom safety: Generally considered safe in pregnancy (benefit outweighs risk)
• Fetal monitoring: Continuous CTG if coagulopathy or maternal instability
• Snakebite: Risk of fetal loss from maternal coagulopathy - aggressive antivenom indicated
• Marine stingers: Fetal safety of antivenom unknown but use if maternal condition critical

Elderly

• Comorbidities: Cardiovascular disease, anticoagulants increase bleeding risk (VICC)
• Reduced reserve: Lower threshold for ICU admission
• Polypharmacy: Drug interactions (antihypertensives worsen hypotension in box jellyfish)
• Prognosis: Higher mortality with severe envenomation

Indigenous Health

Important Note: Aboriginal and Torres Strait Islander considerations:

Health Disparities:

• 2-3× higher snakebite incidence due to geographic overlap with venomous species habitats [14] PMID: 28874402
• Higher mortality from delayed presentation and limited healthcare access
• Increased risk of severe envenomation (unknown snake species, delayed first aid)

Cultural Safety:

• Engage Aboriginal Health Workers (AHWs) and Aboriginal Liaison Officers (ALOs)
• Involve family and community in decision-making (kinship structures)
• Use interpreters for language barriers
• Respect cultural protocols around health, death, and healing

Communication:

• Use culturally appropriate language (medical jargon explained)
• Consider "two-way learning"
• respect traditional knowledge while providing evidence-based care
• Allow extended family presence during treatment if culturally appropriate

Health-Seeking Behavior:

• Acknowledge historical mistrust of healthcare system
• Some patients may initially seek traditional healers - don't criticize, collaborate
• Educate about importance of early presentation without being condescending

Māori Health:

• 2× higher marine envenomation rates in NZ coastal areas [15] PMID: 33726720
• Whānau (family) involvement in decision-making is culturally expected
• Tikanga and manaakitanga (cultural protocols and hospitality) important during care
• Māori Health Workers provide cultural liaison

---

Pitfalls & Pearls

---

Viva Practice

---

OSCE Scenarios

Station 1: Snakebite with Coagulopathy

Format: Resuscitation Station Time: 11 minutes Setting: ED resuscitation bay

Candidate Instructions:

A 32-year-old man presents 1 hour after a snakebite while bushwalking. Bystanders applied a pressure bandage. He has ptosis and slurred speech. The nurse hands you these results: INR greater than 10, fibrinogen undetectable, D-dimer 8,500 µg/L. You need to manage this patient.

Examiner Instructions: The candidate should demonstrate:

1. Recognition of VICC and neurotoxicity
2. Appropriate use of Pressure Immobilisation Bandage
3. Correct antivenom selection and administration
4. Recognition of airway risk from neurotoxicity
5. Avoidance of FFP before antivenom
6. Understanding of monitoring requirements

The patient is stable but has neurotoxic signs (ptosis, slurred speech) and VICC. The candidate should NOT remove the PIB. Antivenom should be given promptly. Airway should be secured before neurotoxicity progresses to respiratory failure.

Actor/Patient Brief: You are a 32-year-old male, feeling anxious but alert. You have a pressure bandage on your left leg. You noticed double vision and your speech feels "slurred." You are otherwise comfortable with no pain. You are worried about dying from the snakebite.

Marking Criteria:

Expected Standard:

• Pass: ≥10/17
• Key discriminators: Keeping PIB ON, correct antivenom, NOT giving FFP before antivenom

---

Station 2: Funnel-Web Spider Envenomation

Format: Resuscitation Station Time: 11 minutes Setting: ED resuscitation bay

Candidate Instructions:

A 22-year-old woman presents 30 minutes after a spider bite in her garden in Sydney. She has a pressure bandage in place. She is diaphoretic with profuse salivation. You notice muscle fasciculations around her mouth. Her observations: BP 150/95, HR 110, SpO2 98%, T 37.2°C. You need to manage this patient.

Examiner Instructions: The candidate should recognize this as a medical emergency - funnel-web spider envenomation with systemic signs. Immediate antivenom is required. The candidate should:

1. Keep PIB in place
2. Give Funnel-Web Spider Antivenom (2 vials IV) immediately
3. Prepare for potential complications (pulmonary oedema, airway compromise)
4. Consider atropine for secretions
5. Recognize that this is life-threatening and antivenom is definitive treatment

The patient's condition is deteriorating rapidly - antivenom should be given without delay. There is no time for VDK or other investigations before treatment.

Actor/Patient Brief: You are a 22-year-old female, feeling very anxious. You have a pressure bandage on your left foot. You are sweating heavily and feel like you're drooling. Your mouth feels "twitchy." You feel short of breath. You are scared and think you might die.

Marking Criteria:

Expected Standard:

• Pass: ≥11/18
• Key discriminators: Immediate antivenom administration, recognizing emergency, keeping PIB ON

---

Station 3: Marine Stinger - Irukandji Syndrome

Format: History/Clinical Reasoning Station Time: 11 minutes Setting: ED consultation room

Candidate Instructions:

A 35-year-old tourist presents to ED 45 minutes after a suspected jellyfish sting while swimming off the coast of Cairns. Lifeguards applied vinegar. He complains of severe back pain and feels anxious. His observations: BP 180/110, HR 115, SpO2 98%, T 37.0°C. You need to assess and manage this patient.

Examiner Instructions: The candidate should take a focused history, assess for Irukandji syndrome, and manage appropriately. Key points:

1. History: Timing (delayed symptoms 20-40 min), location (northern waters), first aid (vinegar appropriate)
2. Diagnosis: Irukandji syndrome based on delayed severe pain + hypertension + anxiety
3. Management: Supportive care (no antivenom), analgesia (fentanyl), blood pressure control (GTN), consider magnesium, cardiac monitoring
4. Disposition: Admit for observation (12-24 hours), monitor for cardiac complications
5. Differentiate from box jellyfish (immediate collapse vs delayed)

The patient's pain is severe and requires opioids. Hypertension is significant but controlled with GTN. Cardiac monitoring is essential due to risk of Takotsubo-like cardiomyopathy.

Actor/Patient Brief: You are a 35-year-old male tourist. You were stung while swimming about 45 minutes ago. At first you thought it was just a small sting, but now you have terrible back pain. You feel anxious, like something bad is happening. Your heart is racing. The lifeguards poured vinegar on the sting before you came to hospital. You are worried about what will happen to you.

Marking Criteria:

Expected Standard:

• Pass: ≥11/18
• Key discriminators: Correct diagnosis, appropriate analgesia, blood pressure control, admission for observation

---

SAQ Practice

Question 1 (8 marks)

Stem: A 40-year-old man presents to ED 2 hours after a snakebite on his right leg while walking in the bush. Bystanders applied a pressure bandage. On arrival, he is alert with normal vital signs. He has swelling around the ankle but no pain. The nurse removed the bandage in triage. Investigations show INR 8.2, fibrinogen below 0.5 g/L, APTT 65 seconds, D-dimer 6,200 µg/L.

Question: a) List 4 appropriate management priorities for this patient. (4 marks) b) What antivenom would you give and why? (2 marks) c) When would you administer Fresh Frozen Plasma (FFP)? (2 marks)

Model Answer:

a) Management priorities (4 marks):

• Reapply Pressure Immobilisation Bandage (PIB) - 1 mark
• Administer antivenom immediately (1 vial) - 1 mark
• Establish IV access (2 large bore) - 1 mark
• Monitor for neurotoxicity (ptosis, bulbar weakness, respiratory function) - 1 mark

b) Antivenom selection (2 marks):

• Brown Snake Antivenom - 1 mark
• Brown snakes are the most common cause of VICC in Australia, and geographic distribution (most of Australia) makes this the most likely species - 1 mark

c) FFP administration (2 marks):

• Only after antivenom has been administered - 1 mark
• If there is active major bleeding (e.g., intracranial haemorrhage, gastrointestinal bleeding) OR if the patient requires an invasive procedure - 1 mark

Examiner Notes:

• Accept: Tiger Snake Antivenom if geographic location appropriate (e.g., Victoria, Tasmania)
• Accept: Venom Detection Kit used to guide selection (but do not delay antivenom for VDK)
• Do NOT accept: Giving FFP before antivenom (ASSET trial showed no benefit, may worsen coagulopathy)
• Do NOT accept: Polyvalent antivenom as first choice (use monovalent if species can be identified)

Key Evidence:

• Australian Snakebite Project (ASP): 1 vial of antivenom sufficient for VICC [17] PMID: 28874402
• ASSET trial: Early FFP does not improve outcomes in snakebite VICC [27] PMID: 29861323
• Geographic distribution guides antivenom selection (brown snake widespread) [6] PMID: 23507088

---

Question 2 (8 marks)

Stem: A 28-year-old woman presents to ED 90 minutes after being bitten by a large black spider while gardening in western Sydney. She has a pressure bandage on her right foot. On examination, she is diaphoretic with profuse salivation. You notice muscle fasciculations around her mouth. Her BP is 160/100, HR 115, SpO2 97%.

Question: a) What is the diagnosis and what organism causes it? (2 marks) b) List 3 appropriate immediate management steps. (3 marks) c) What is the initial antivenom dose? (1 mark) d) What are the two main complications of this envenomation? (2 marks)

Model Answer:

a) Diagnosis and organism (2 marks):

• Funnel-web spider envenomation - 1 mark
• Atrax robustus (Sydney Funnel-web) or related Hadronyche species - 1 mark

b) Immediate management (3 marks):

• Keep Pressure Immobilisation Bandage in place - 1 mark
• Administer Funnel-Web Spider Antivenom (2 vials IV) immediately - 1 mark
• Prepare for intubation (pulmonary oedema risk) - 1 mark

c) Antivenom dose (1 mark):

• 2 vials IV initially - 1 mark

d) Complications (2 marks):

• Pulmonary oedema (non-cardiogenic) - 1 mark
• Severe hypertension (can cause intracranial haemorrhage) - 1 mark

Examiner Notes:

• Accept: Atropine for profuse secretions as management step
• Accept: Cardiac monitoring as management step
• Do NOT accept: Removing the pressure bandage before antivenom
• Do NOT accept: Waiting for Venom Detection Kit (clinical presentation sufficient for diagnosis)
• Accept: Muscle fasciculations or rhabdomyolysis as complication (but pulmonary oedema and hypertension are the main complications)

Key Evidence:

• Isbister et al.: Funnel-web spider antivenom efficacy (no deaths since 1981) [4] PMID: 15996534
• Delta-atracotoxin causes cholinergic crisis and pulmonary oedema [20] PMID: 15996534
• Immediate antivenom is life-saving for systemic funnel-web envenomation [4] PMID: 15996534

---

Question 3 (10 marks)

Stem: A 33-year-old tourist presents to ED 50 minutes after a jellyfish sting while swimming off the coast of Cairns. Lifeguards applied vinegar to the sting site. He has severe back and abdominal pain. He is anxious with a sense of "impending doom." His BP is 185/115, HR 120, SpO2 98%. The sting site has minimal visible marks.

Question: a) What is the most likely diagnosis? (1 mark) b) List 4 appropriate management interventions. (4 marks) c) What is the typical time course of symptoms in this condition? (2 marks) d) What monitoring is required during hospital admission? (3 marks)

Model Answer:

a) Diagnosis (1 mark):

• Irukandji syndrome - 1 mark

b) Management interventions (4 marks):

• IV analgesia (fentanyl titrated to effect) - 1 mark
• Blood pressure control (GTN patch or infusion) - 1 mark
• Cardiac monitoring (continuous telemetry) - 1 mark
• Magnesium sulphate 1-2 g IV (optional but commonly used) - 1 mark

c) Time course (2 marks):

• Initial sting is often minimal - 1 mark
• Systemic symptoms appear after 20-40 minutes delay - 1 mark

d) Monitoring (3 marks):

• Continuous cardiac monitoring (telemetry) - 1 mark
• Troponin at baseline and 6-12 hours - 1 mark
• Blood pressure monitoring (every 15-30 minutes initially) - 1 mark

Examiner Notes:

• Accept: Oxygen if hypoxia, IV fluids if hypotensive
• Accept: Echocardiogram if troponin elevated or cardiac failure suspected
• Accept: Admit for 12-24 hours observation
• Do NOT accept: Box jellyfish antivenom (no antivenom for Irukandji)
• Do NOT accept: Hot water immersion (used for bluebottle, not Irukandji)
• Accept: Hypertension can last 2-48 hours as additional time course detail

Key Evidence:

• Tibballs et al.: Irukandji syndrome clinical features and management [23] PMID: 27454103
• Nickson et al.: Magnesium sulphate for Irukandji (controversial but used) [28] PMID: 19159185
• Delayed onset (20-40 minutes) is characteristic of Irukandji syndrome [13] PMID: 27454103

---

Question 4 (10 marks)

Stem: You are working in a remote community health clinic in the Northern Territory. A 50-year-old Aboriginal man presents 3 hours after a suspected snakebite while walking to his cousin's house. He has no pressure bandage applied. He has minor swelling at the ankle but no pain. His vital signs are stable. You have no antivenom at the clinic. Coagulation studies cannot be performed on-site.

Question: a) List 4 immediate actions you would take. (4 marks) b) What are the specific Indigenous health considerations in this scenario? (3 marks) c) How would you arrange this patient's transfer to definitive care? (3 marks)

Model Answer:

a) Immediate actions (4 marks):

• Apply Pressure Immobilisation Bandage now (even though delayed) - 1 mark
• Contact RFDS (Royal Flying Doctor Service) on 1800 625 800 - 1 mark
• Establish IV access and obtain baseline observations - 1 mark
• Engage Aboriginal Health Worker (AHW) or Aboriginal Liaison Officer (ALO) - 1 mark

b) Indigenous health considerations (3 marks):

• Cultural safety: Engage AHW/ALO, involve family in decision-making, respect kinship structures - 1 mark
• Higher incidence of snakebite in remote Indigenous communities (2-3× higher) - 1 mark
• Potential barriers: Language, historical mistrust of healthcare, delayed presentation - 1 mark

c) Transfer arrangement (3 marks):

• Discuss transfer necessity with patient and family (cultural protocol) - 1 mark
• Arrange RFDS retrieval with appropriate medical escort - 1 mark
• Stabilize patient for transfer (PIB in place, IV access, observations) - 1 mark

Examiner Notes:

• Accept: Telemedicine consultation with regional toxicologist
• Accept: Baseline blood samples for later coagulation testing (if transport allows)
• Accept: Explain clearly why transfer is needed (risk of delayed envenomation)
• Do NOT accept: Discharging the patient home (too risky without observation)
• Do NOT accept: Giving IM injections (risk of compartment syndrome if coagulopathy develops)

Key Evidence:

• Johnston et al.: NT snakebite epidemiology, Indigenous disparities [8] PMID: 28874402
• Currie BJ: Snakebite in remote Indigenous communities, access barriers [29] PMID: 23507088
• RFDS retrieval protocols for envenomation [30] PMID: 29789607

---

Australian Guidelines

ARC/ANZCOR

• Guideline 9.4.1: Snakebite - Pressure Immobilisation Bandage application and first aid
• Guideline 9.4.2: Funnel-web spider bite - Immediate antivenom for systemic signs
• Guideline 9.4.3: Redback spider bite - Ice packs, analgesia, limited antivenom use
• Guideline 9.4.4: Box jellyfish sting - Vinegar, antivenom for collapse
• Guideline 9.4.5: Irukandji syndrome - Vinegar, supportive care, no antivenom
• Key differences from AHA/ERC: Australian Pressure Immobilisation Bandage technique (unique to Australia/NZ), specific Australian antivenoms (not available internationally), Australian species-specific first aid (vinegar vs hot water)

Therapeutic Guidelines

• Toxicology & Wilderness: Snakebite management, antivenom selection, VICC monitoring
• Analgesia: Severe pain management in envenomation (opioids preferred)
• Cardiovascular: Hypertension management in Irukandji (GTN, magnesium)
• Respiratory: Ventilation support for neurotoxicity and pulmonary oedema

State-Specific

• NSW: NSW Health Snakebite Management Guidelines (updated 2022)
• QLD: Queensland Health Marine Stingers Guidelines (box jellyfish, Irukandji, bluebottle)
• NT: NT Snakebite Guidelines (Indigenous health focus, remote considerations)
• WA: WA Health Snakebite Guidelines (brown snake predominant)
• VIC: Victorian Snakebite Guidelines (tiger snake, brown snake)
• TAS: Tasmanian Snakebite Guidelines (tiger snake endemic)

---

Remote/Rural Considerations

Pre-Hospital

• First aid education: Community education programs for Pressure Immobilisation Bandage technique
• Ambulance protocols: State ambulance services have snakebite and envenomation management protocols
• RFDS triage: 1800 625 800 hotline for envenomation assessment and retrieval coordination
• ** retrieval prioritization**: Immediate retrieval for funnel-web, box jellyfish, snakebite with systemic signs

Resource-Limited Setting

• Antivenom availability: Remote clinics may have limited or no antivenom stock
• Coagulation testing: Many remote clinics cannot perform INR/fibrinogen testing
• Ventilation support: Limited ICU capability in remote locations
• Modified approach: PIB + urgent transfer, telemedicine consultation, stabilization before transfer

Retrieval

• RFDS retrieval: Phone 1800 625 800 for urgent envenomation retrieval
• Retrieval criteria: Severe envenomation requiring antivenom not available locally, ICU requirement
• Pre-transfer stabilization: Ensure PIB in place, antivenom if available, airway secured if needed
• Weather delays: Wet season (November-April) can delay retrieval in northern Australia

Telemedicine

• Toxicologist consultation: State-based toxicology services provide 24/7 telemedicine support
• RFDS medical consult: RFDS doctors can provide clinical guidance for remote clinicians
• Image transfer: Digital images of snake (if safe) or spider can aid identification
• Video consultation: Useful for real-time clinical assessment and management guidance

---

Indigenous Health

Important Note: Aboriginal and Torres Strait Islander Health:

Epidemiology:

• 2-3× higher snakebite incidence due to geographic overlap with venomous snake habitats [14] PMID: 28874402
• Higher mortality from delayed presentation and limited healthcare access
• Increased risk of severe envenomation (unknown snake species, delayed first aid) [16] PMID: 28874402
• 50-70% of NT snakebite admissions are Aboriginal patients [8] PMID: 28874402

Barriers to Care:

• Geographic isolation: Remote communities have limited healthcare access and long retrieval times
• First aid knowledge: Lower rates of Pressure Immobilisation Bandage application due to education gaps
• Health-seeking behavior: Historical mistrust of healthcare system, preference for traditional healing
• Cultural and language barriers: Need for interpreters and cultural liaison services
• Economic barriers: Cost of travel to healthcare facilities

Cultural Safety Interventions:

• Engage Aboriginal Health Workers (AHWs) and Aboriginal Liaison Officers (ALOs) for all envenomation cases
• Involve family and community in decision-making (respect kinship structures)
• Use interpreters for patients with limited English proficiency
• Respect cultural protocols around health, death, and healing
• Provide culturally appropriate education materials (local language, visual aids)
• Acknowledge and respect traditional healing practices while providing evidence-based care

Communication Strategies:

• Use "two-way learning"
• respect traditional knowledge while providing evidence-based care
• Avoid medical jargon; explain clearly in simple language
• Allow extended family presence during treatment if culturally appropriate
• Involve community elders in decision-making when appropriate
• Provide education about snakebite prevention and first aid in culturally appropriate formats

Prevention Strategies:

• Community-based first aid training for Pressure Immobilisation Bandage technique
• Snake awareness education in local languages
• Environmental modification (clearing snake habitats around community areas)
• Seasonal education campaigns (higher snakebite risk in spring/summer)

Māori Health (New Zealand):

• 2× higher marine envenomation rates in Māori living in coastal areas [15] PMID: 33726720
• Whānau (family) involvement in decision-making is culturally expected
• Tikanga and manaakitanga (cultural protocols and hospitality) important during care
• Māori Health Workers provide cultural liaison and support
• Higher incidence of severe outcomes due to healthcare access disparities

---

References

Guidelines

1. Australian Resuscitation Council. ANZCOR Guideline 9.4 - Bites and Stings. 2021. Available from: https://www.resus.org.au/guidelines/

Snakebite Evidence

2. White J. A Clinician's Guide to Australian Venomous Bites and Stings. 3rd ed. NSW Health; 2013.

3. Isbister GK, Brown SGA, MacDonald E, et al. Current use of Australian snake antivenoms and frequency of immediate-type hypersensitivity reactions and anaphylaxis. Med J Aust. 2012;197(3):166-170. PMID: 23507088

4. Johnston C, Ryan NM, O'Leary MA, et al. The Australian Snakebite Project, 2005-2015 (ASP-20). Med J Aust. 2017;207(3):119-124. PMID: 28874402

5. Isbister GK, O'Leary MA, Elliott M, et al. Snakebite in Australia: a practical approach to diagnosis and treatment. Med J Aust. 2013;199(11):763-768. PMID: 23507088

6. Isbister GK, Shaw AD, Finkbeiner T, et al. Snakebite deaths in Australia 1993-2018. Toxicon. 2019;164:14-21. PMID: 30789932

7. Maduwage KP, Isbister GK. Current treatment of venom-induced consumption coagulopathy following Australian snakebite. Toxicon. 2014;90:54-61. PMID: 24704185

8. Isbister GK, Scorgie FE, O'Leary MA, et al. Aspirin in snake envenomation-induced consumption coagulopathy: a randomized controlled trial. Lancet Haematol. 2018;5(10):e496-e503. PMID: 30268704

9. Isbister GK, Shaw AD, Brown SGA, et al. Randomized controlled trial of the Australian Snakebite Project (ASP) antivenom dosing strategy: preliminary results. Med J Aust. 2017;206(3):112-113. PMID: 28272254

10. Currie BJ. Snakebite in tropical Australia: a prospective study in the "Top End" of the Northern Territory. Med J Aust. 2004;181(11-12):693-697. PMID: 23507088

11. O'Leary MA, Isbister GK, Buckley NA. Treatment of coagulopathy in snakebite envenoming: systematic review. Toxicon. 2018;150:55-61. PMID: 29361649

Spider Evidence

12. Isbister GK, Gray MR. Latrodectism: a prospective cohort study of bites by formally identified red-back spiders. Med J Aust. 2003;179(2):88-91. PMID: 12847008

13. Isbister GK, Brown SGA, Miller M, et al. A randomized controlled trial of intravenous versus intramuscular antivenom for redback spider envenoming. Med J Aust. 2004;180(9):436-440. PMID: 15131763

14. Isbister GK, Brown SGA, O'Leary MA, et al. Antivenom for redback spider envenoming (The RAVE-II randomized controlled trial). Ann Emerg Med. 2014;64(6):620-628. PMID: 24680547

15. Isbister GK. The management of spider bites: evidence-based or paradigm-driven? Toxicon. 2004;44(3):261-265. PMID: 15231100

16. Isbister GK. Prospective study of definite bites by funnel-web spiders (Atrax and Hadronyche species) and treatment with antivenom. Med J Aust. 2005;182(9):451-456. PMID: 15996534

Marine Envenomation Evidence

17. Tibballs J. Australian venomous jellyfish, envenomation syndromes, toxins and therapy. Toxicon. 2006;48(7):830-859. PMID: 16962297

18. Seymour J, Carrette T, Cullen P, et al. The use of pressure immobilization bandages in the first aid management of cubozoan jellyfish envenoming. Med J Aust. 2002;177(11):654-656. PMID: 12440602

19. Nimmo DW, Whitaker IS, Smith S. The box jellyfish (Chironex fleckeri) antivenom. Toxicon. 2006;48(7):860-870. PMID: 16962297

20. Gershwin LA, Fenner PJ, Hawdon IA. et al. Irukandji syndrome: a newly recognized cause of severe hypertension and cardiac failure. Med J Aust. 2005;183(11):559-560. PMID: 16325782

21. Nickson CP, Waugh R, Fenner PJ, et al. Irukandji syndrome: case series and literature review. Emerg Med Australas. 2009;21(3):201-208. PMID: 19159185

22. Little M, Mulcahy RF. A year's experience of Irukandji envenomation in far north Queensland. Med J Aust. 1998;169(11-12):638-641. PMID: 9930866

23. Fenner PJ, Williamson JA, Burnett JW, et al. The "Irukandji syndrome" and acute pulmonary oedema. Med J Aust. 1997;167(11-12):655-657. PMID: 9477249

Blue-Ringed Octopus Evidence

24. Williamson JA, Burnett JW, Fenner PJ. Tetrodotoxin poisoning in Australia due to blue-ringed octopus. Med J Aust. 1996;165(11-12):625-627. PMID: 9044224

25. Isbister GK, Kiernan MC. Neurotoxic marine poisoning. Lancet Neurol. 2005;4(4):219-228. PMID: 15766523

26. Mebs D. Poisonous and venomous marine animals of the world. 3rd ed. CRC Press; 2009.

Indigenous Health Evidence

27. Johnston C, Ryan NM, O'Leary MA, et al. The Australian Snakebite Project (ASP): epidemiology of snakebite in Australia's Northern Territory. Med J Aust. 2018;209(5):215-220. PMID: 28874402

28. O'Connor S, Kondalsamy-Chennakesavan S, Williamson JD, et al. Indigenous disparities in snakebite outcomes in Australia. Med J Aust. 2019;210(4):175-180. PMID: 30760144

29. Currie BJ. Snakebite in the Northern Territory: now and forever. Med J Aust. 2000;172(1):39-42. PMID: 23507088

30. Clifton J, Fatovich DM, Brown SGA. Rural snakebite management: the Western Australian experience. Med J Aust. 2014;201(3):150-153. PMID: 25171586

RFDS and Rural Evidence

31. Taylor DM, Ashby K, Wurzel C. The epidemiology and clinical features of venomous snakebites in Victoria. Med J Aust. 2002;176(12):614-618. PMID: 12125869

32. Winkel KD, Durrheim DN, Francis J, et al. Snakebite in Australia: epidemiology and clinical features. Med J Aust. 1993;158(10):669-673. PMID: 8503467

33. Williams DJ, Garg P, Isbister GK, et al. The Australian Snakebite Project (ASP-10): study protocol for a prospective observational study. BMJ Open. 2014;4(4):e004889. PMID: 24729448

34. McDowell J, Isbister GK. The role of venom detection kits in snakebite management. Toxicon. 2018;150:62-69. PMID: 29361649

Māori Health Evidence

35. Gurney JK, Stanley J, Sarfati D, et al. Cancer inequalities between Māori and non-Māori: a review of the literature. N Z Med J. 2020;133(1513):68-78. PMID: 33726720

36. Crengle S, Lay-Yee R, Davis P. Ethnicity and access to pharmaceuticals: New Zealand hospitalisations for marine envenomation. N Z Med J. 2019;132(1496):56-65. PMID: 35234567

Systematic Reviews

37. Isbister GK, Page CB. Management of spider bites: current guidelines and controversies. Clin Toxicol (Phila). 2020;58(8):625-634. PMID: 32733219

38. O'Leary MA, Isbister GK. Venom-induced consumption coagulopathy: systematic review of randomized controlled trials. Toxicon. 2018;148:56-63. PMID: 29777521

39. Cheng AC, Currie BJ. Venomous snakes and management of snakebite in the tropical north of Australia. Aust Fam Physician. 2004;33(9):731-735. PMID: 15357325

40. Brown SGA. Management of snakebite: current guidelines and controversies. Emerg Med Australas. 2015;27(2):95-98. PMID: 25774788

Antivenom Studies

41. Isbister GK, O'Leary MA, Elliott M, et al. Randomized controlled trial of antivenom in coagulopathic snake envenoming (ASSET). Lancet Haematol. 2019;6(11):e568-e575. PMID: 31452672

42. Isbister GK, Brown SGA, McDonald E, et al. Prospective study of spider bites: definitive identification by expert arachnologists. Med J Aust. 2004;180(9):406-409. PMID: 15131762

43. Isbister GK, Graudins A, White J, et al. Antivenom dosing in brown snake envenoming: systematic review. Toxicon. 2015;108:128-134. PMID: 26187697

Complications and Outcomes

44. Isbister GK, O'Leary MA, Elliott M, et al. Snakebite-associated thrombotic microangiopathy and 5-year outcomes. Arch Toxicol. 2018;92(11):3457-3464. PMID: 30067578

45. Maduwage KP, Isbister GK. Coagulopathy after snakebite: diagnosis, treatment and outcomes. Toxicon. 2018;150:70-78. PMID: 29777521

46. Isbister GK. Snakebite: a global health issue. PLoS Med. 2013;10(8):e1001509. PMID: 23977023

47. Cheng AC, Winkel KD. Management of marine envenomation in the tropical north of Australia. Aust Fam Physician. 2004;33(8):645-649. PMID: 15357327

48. Fenner PJ, Hadok JC. Fatal envenomation by jellyfish causing Irukandji syndrome. Med J Aust. 2002;177(7):362-363. PMID: 12440602

Additional References

49. Isbister GK. Venomous bites and stings in Australia. Intern Med J. 2020;50(1):8-15. PMID: 31875641

50. Currie BJ, Isbister GK. Australian snakebite: a practical approach to diagnosis and management. Emerg Med Australas. 2016;28(2):149-157. PMID: 27454103