Toxicology - General Approach

Quick Answer

One-liner: Systematic ABCDE approach, identify toxidrome, decontaminate early, consider antidotes, contact Poisons Information Centre (13 11 26).

The initial approach to any poisoned patient follows a structured ABCDE assessment with simultaneous history-taking and decontamination when indicated. Identify the toxidrome pattern (anticholinergic, cholinergic, sympathomimetic, opioid, sedative) to guide antidote therapy. Activated charcoal within 1 hour for most ingestions. Always consult the Poisons Information Centre (13 11 26 in Australia) for complex cases or when antidote dosing is uncertain. Consider enhanced elimination (urinary alkalinization for salicylates, hemodialysis for toxic alcohols/lithium) based on specific toxins and severity.

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ACEM Exam Focus

Primary Exam Relevance

• Pharmacology: Mechanisms of major antidotes (naloxone, flumazenil, atropine, N-acetylcysteine), drug metabolism (phase I/II), toxicodynamics
• Physiology: Acid-base balance, renal clearance, respiratory drive regulation, autonomic nervous system
• Anatomy: Airway anatomy relevant to aspiration risk

Fellowship Exam Relevance

• Written: High-yield topics include toxidrome identification, activated charcoal indications, specific antidotes, Rumack-Matthew nomogram, urinary alkalinization
• OSCE: Likely scenarios include managing an unconscious overdose patient, poisoned patient with respiratory depression, communication with family about overdose, decision-making about decontamination
• Key domains tested: Medical Expert (recognition, management), Communicator (family discussions), Leader (resource utilisation, Poisons Centre consultation)

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Key Points

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Epidemiology

Australian/NZ Specific

• Self-poisoning leading cause of ED presentation in 15-30 age group
• Paracetamol most common single-agent overdose
• Polypharmacy overdoses increasing (benzodiazepines + antidepressants + alcohol)
• Indigenous populations 2-3x higher ED presentation rates for overdose
• Remote/rural areas present later, higher severity

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Pathophysiology

Mechanisms of Toxicity

Absorption

• Gastrointestinal: Most common route (oral ingestion)
• Dermal/ocular: Pesticides, hydrocarbons, corrosives
• Inhalation: Gases, volatile substances
• Parenteral: IV drug abuse, iatrogenic

Distribution

• Volume of distribution determines elimination strategy
  • Small Vd (e.g., lithium, salicylates) - amenable to dialysis
  • Large Vd (e.g., TCAs, tricyclic antidepressants) - dialysis ineffective
• Protein binding - affects displacement interactions and dialysis clearance

Metabolism

• Phase I reactions (oxidation, reduction, hydrolysis) - CYP450 system
• Phase II reactions (conjugation) - glucuronidation, sulfation
• Toxic metabolites:
  • Paracetamol → NAPQI (hepatotoxic)
  • Methanol → Formic acid (optic neuropathy)
  • Ethylene glycol → Glycolic/Oxalic acid (renal toxicity)

Elimination

• Renal excretion - Primary for many toxins (enhanced by urinary pH changes)
• Hepatic metabolism - Cytochrome P450 enzymes
• Pulmonary excretion - Volatile substances (alcohol, gases)

Toxicokinetic Principles

Ingestion → Absorption → Distribution → Metabolism → Elimination

Time-dependent toxicity:

• Peak toxicity occurs at different times depending on formulation
  • "Immediate-release: 2-4 hours"
  • "Sustained-release: 4-12 hours"
  • "Extended-release: 12-24 hours"

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Clinical Approach

Recognition

Triggers for considering poisoning:

• Unexplained altered mental status
• Respiratory depression without obvious cause
• Cardiac arrhythmias in young healthy patient
• Metabolic acidosis with elevated anion gap
• New-onset seizures
• Multiple unexplained symptoms

Initial Assessment

Primary Survey (ABCDE)

A - Airway

• Assess: Patency, protection, presence of vomitus
• Intervene:
  • Head tilt-chin lift (no cervical spine concern)
  • Guedel airway, nasopharyngeal airway
  • "Rapid sequence intubation if:"
    • GCS below 8
    • Inability to protect airway
    • Respiratory failure
    • Anticipated deterioration

B - Breathing

• Assess: Respiratory rate, oxygen saturation, work of breathing
• Intervene:
  • Supplemental oxygen (target SpO2 94-98%)
  • Non-invasive ventilation for respiratory depression
  • "Intubation and ventilation if:"
    • RR below 8/min and unresponsive
    • PaO2 below 60 mmHg on oxygen
    • PaCO2 greater than 50 mmHg with acidosis

C - Circulation

• Assess: Heart rate, blood pressure, capillary refill, ECG
• Intervene:
  • IV access (2 large bore)
  • Fluid resuscitation (crystalloid)
  • Vasopressors if refractory hypotension
  • Arrhythmia treatment per ACLS

D - Disability

• Assess: GCS, pupils, blood glucose, focal neurology
• Intervene:
  • Thiamine 100 mg IV (if alcohol suspected)
  • Glucose (if hypoglycaemic)
  • Narcan trial if opioid suspected
  • Seizure management

E - Exposure/Environment

• Assess: Temperature, skin findings, signs of trauma, needle marks
• Intervene:
  • Remove contaminated clothing
  • Decontaminate skin (dermal exposures)
  • Temperature management
  • Full examination for hidden ingestion (pockets, bags)

History

Key Questions

Red Flag Symptoms

Examination

General Inspection

• Level of consciousness (GCS)
• Respiratory pattern (rate, depth, effort)
• Skin: color, temperature, moisture, needle marks
• Odour: alcohol, cyanide (bitter almonds), organophosphates (garlic-like), paracetamol (vomit)

Specific Findings

Toxidrome Recognition

The 5 Classic Toxidromes:

Mnemonic for Anticholinergic: "Hot as a hare, dry as a bone, red as a beet, blind as a bat, mad as a hatter"

Mnemonic for Cholinergic (DUMBELS):

• Diarrhoea
• Urination
• Miosis
• Bradycardia, Bronchorrhea, Bronchospasm
• Emesis
• Lacrimation
• Salivation, Sweating

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Investigations

Immediate (Resus Bay)

Standard ED Workup

Toxicology-Specific Tests

Advanced/Specialist

Point-of-Care Ultrasound

Applications in toxicology:

• Gastric ultrasound: Estimate gastric contents before intubation
• IV access guidance: Difficult access cases
• Focused cardiac echo: Assess cardiac function in cardiotoxic overdoses
• Lung ultrasound: Detect pulmonary oedema (opioids, aspirin)
• Abdominal ultrasound: Identify radiopaque tablets (iron)

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Management

Immediate Management (First 10 minutes)

1. ABCDE assessment and stabilization
2. IV access (2 large bore cannulas)
3. Cardiac monitoring, continuous pulse oximetry
4. 12-lead ECG
5. Blood glucose check
6. Bloods: FBC, U&E, LFT, coagulation, paracetamol level, salicylate level
7. Arterial blood gas
8. Urine for toxicology screen
9. Consider antidote administration based on toxidrome
10. Consult Poisons Information Centre (13 11 26) if uncertain

Resuscitation

Airway Management

Indications for intubation:

• GCS below 8
• Inability to protect airway (loss of gag reflex)
• Respiratory failure (PaO2 below 60 mmHg, PaCO2 greater than 50 mmHg)
• Anticipated clinical deterioration
• Required for decontamination (charcoal, WBI) in decreased consciousness

RSI considerations:

• Reduced drug doses in sedative/opioid overdose
• Use short-acting agents (propofol, remifentanil)
• Have antidotes readily available (naloxone, flumazenil - use cautiously)
• Protect against aspiration (NG tube after intubation if WBI)

Breathing Support

Oxygen:

• Target SpO2 94-98%
• Higher targets in CO poisoning (100%), methemoglobinemia (100%)

Ventilation:

• Normal ventilation for most overdoses
• Hyperventilation for salicylate toxicity (target PaCO2 25-30 mmHg)
• Permissive hypercapnia in obstructive lung disease

Circulatory Support

Fluid resuscitation:

• Crystalloid bolus (500-1000 mL) for hypotension
• Vasopressors if refractory (norepinephrine first-line)
• Consider calcium for CCB-induced hypotension

Arrhythmia management:

• Sodium bicarbonate for TCA-induced QRS widening
• Magnesium for Torsades de Pointes
• Standard ACLS for other arrhythmias

Decontamination

Activated Charcoal

Mechanism: Adsorbs toxins in gastrointestinal tract, prevents absorption

Indications:

• Within 1 hour of ingestion for most toxins [7]
• Up to 2 hours for drugs with delayed gastric emptying:
  • Anticholinergics (TCAs, antihistamines)
  • Opioids
  • Salicylates
  • Sustained/extended-release formulations
• Massive/life-threatening ingestions (up to 4 hours)

Contraindications:

• Unprotected airway (GCS below 8 or loss of gag reflex)
• Corrosive ingestion (acids/alkalis)
• Hydrocarbon ingestion (aspiration risk)
• Gastrointestinal obstruction
• Charcoal non-binders (iron, lithium, alcohols, acids/alkalis)

Dosing:

• Adults: 50 g (1 g/kg up to 50 g) PO/NG
• Children: 1 g/kg PO/NG (maximum 50 g)
• May repeat dose for extended-release preparations

Administration:

• Mix with water (240 mL for 50 g charcoal)
• Administer via NG tube if unable to swallow
• Consider antiemetic before administration to reduce vomiting risk

Gastric Lavage

Indications (rare):

• Life-threatening ingestion
• Within 1 hour of ingestion
• Contraindications to charcoal present
• Toxicity not adequately controlled by antidotes

Contraindications:

• Corrosive ingestion
• Hydrocarbon ingestion
• Unprotected airway
• Coagulopathy

Technique:

• Large-bore orogastric tube (36-40 Fr)
• Left lateral decubitus position
• Small aliquots (200-300 mL) until clear
• Maximum 1 hour after ingestion

Whole Bowel Irrigation (WBI)

Mechanism: Polyethylene glycol solution flushes entire GI tract

Indications:

• Body packers/stuffers (drug smugglers)
• Extended-release/enteric-coated medications
• Substances not adsorbed by charcoal (iron, lithium, lead)
• Large quantities of toxic substances

Contraindications:

• Bowel obstruction
• GI perforation
• Unprotected airway
• Haemodynamic instability
• Ileus

Technique:

• Polyethylene glycol electrolyte solution
• Adults: 1.5-2 L/hour until rectal effluent clear
• Children: 25-40 mL/kg/hour
• Nasogastric administration required

Dermal Decontamination

Procedure:

1. Remove contaminated clothing
2. Brush off dry chemicals (avoid water on reactive substances like phosphorus)
3. Irrigate with copious water (minimum 15 minutes for acids/alkalis)
4. Use specific antidotes if available (calcium gluconate gel for hydrofluoric acid)

Enhanced Elimination

Urinary Alkalinization

Indications:

• Salicylate toxicity (primary indication)
• Phenobarbital toxicity (less effective than dialysis)
• 2,4-Dichlorophenoxyacetic acid

Mechanism:

• Ion trapping: Alkaline urine prevents reabsorption of weak acids
• Increases salicylate clearance 10-18 fold [8]

Protocol:

• Target urine pH: 7.5-8.0
• Serum pH target: 7.45-7.55 (avoid greater than 7.60)
• Potassium replacement essential (hypokalaemia prevents alkalinization)

Sodium bicarbonate regimen:

• Initial bolus: 1-2 mEq/kg IV over 1-2 min (8.4% solution)
• Maintenance infusion: 150 mEq NaHCO3 in 1L D5W at 250 mL/hour
• Titrate to urine pH

Monitoring:

• Urine pH q1h
• Serum electrolytes q2h
• ABG q4h
• Fluid balance

Contraindications:

• Severe pulmonary oedema
• Renal failure (ineffective)
• Hypokalaemia (must correct first)

Multiple-Dose Activated Charcoal (MDAC)

Indications:

• Life-threatening ingestions of:
  • Carbamazepine
  • Dapsone
  • Phenobarbital
  • Quinine
  • Theophylline

Dosing:

• Initial: 50 g PO/NG
• Subsequent: 12.5-25 g PO/NG q4h (alternating with cathartic if needed)
• Continue until clinical improvement or drug level undetectable

Contraindications:

• Unprotected airway
• GI obstruction
• Ileus

Hemodialysis/Hemoperfusion

EXTRIP (Extracorporeal Treatments in Poisoning) Guidelines [9]:

Hemodialysis advantages:

• Corrects metabolic acidosis
• Removes toxic metabolites
• Rapid clearance (large surface area)

Hemoperfusion advantages:

• Better for large protein-bound molecules
• No effect on acid-base status

Antidotes

Naloxone (Opioid Antagonist)

Indications: Opioid-induced respiratory depression

Mechanism: Competitive antagonist at μ-opioid receptors

Dosing:

• Initial: 0.04-0.4 mg IV (start low in chronic opioid users)
• Titrate: 0.1 mg increments q2-3min until RR greater than 12/min
• Maximal testing dose: 10 mg (if no response, reconsider diagnosis) [10]
• For synthetic opioids (fentanyl): May require higher doses (2-5 mg)

Administration routes:

• IV: Most reliable
• IM: Alternative if IV access unavailable
• IN (intranasal): 2 mg spray for community use

Naloxone infusion:

• Indication: Rebound respiratory depression with long-acting opioids
• Dose: Two-thirds of response dose per hour
• Duration: Continue infusion 4-24 hours depending on opioid

Complications:

• Precipitated withdrawal (pain, agitation, vomiting)
• Pulmonary oedema (rare, usually from opioids themselves)
• Seizures (extremely rare)

Contraindications: None - life-threatening emergency

Flumazenil (Benzodiazepine Antagonist)

Indications:

• Pure benzodiazepine overdose with respiratory depression
• Procedural sedation reversal

Mechanism: Competitive antagonist at benzodiazepine binding site on GABA-A receptor

Dosing:

• Initial: 0.2 mg IV over 30 seconds
• Repeat: 0.2 mg q1min until desired response (maximum 1 mg)
• Re-dose frequently (benzodiazepines have longer duration)

CONTRAINDICATED in:

• Suspected TCA co-ingestion (lowers seizure threshold) [11]
• Chronic benzodiazepine dependence (precipitates seizures, withdrawal)
• Seizure disorder
• Head injury
• Arrhythmias

Complications:

• Seizures (most serious)
• Agitation, anxiety
• Autonomic instability

N-acetylcysteine (Paracetamol Antidote)

Indications: Paracetamol toxicity

Mechanism:

• Glutathione precursor
• Direct glutathione substitute
• Detoxifies NAPQI (toxic metabolite)

IV 21-hour protocol [12]:

• Loading: 150 mg/kg over 1 hour
• Second dose: 50 mg/kg over 4 hours
• Third dose: 100 mg/kg over 16 hours

Oral protocol (alternative):

• Loading: 140 mg/kg PO
• Maintenance: 70 mg/kg q4h × 17 doses

Rumack-Matthew Nomogram:

• Plot serum paracetamol level vs time post-ingestion (≥4 hours)
• Treat if level above treatment line (150 µg/mL line at 4 hours)
• Not valid for:
  • Ingestions greater than 24 hours ago
  • Unknown time of ingestion
  • Chronic supratherapeutic ingestion
  • Extended-release formulations (requires serial levels)

Adverse reactions (10-20%):

• Nausea, vomiting (most common)
• Anaphylactoid reactions (rash, bronchospasm, hypotension)
• Anaphylaxis (rare)

Management of reactions:

• Stop infusion
• Antihistamine (promethazine 25 mg IV)
• Consider restarting at slower infusion rate if reaction mild

Sodium Bicarbonate (TCA Antidote)

Indications: TCA toxicity

• QRS duration greater than 100 ms (increased seizure risk)
• QRS duration greater than 160 ms (increased arrhythmia risk)
• Refractory hypotension

Mechanism:

• Increases serum pH (decreases TCA binding to sodium channels)
• Sodium loading (overcomes sodium channel blockade)

Dosing:

• Initial bolus: 1-2 mEq/kg IV over 1-2 min (8.4% solution)
• Repeat: 0.5-1 mEq/kg boluses q5-10min as needed
• Maintenance: 150 mEq NaHCO3 in 1L D5W at 150-250 mL/hour
• Target: Serum pH 7.50-7.55, QRS below 100 ms

Monitoring:

• ECG q5-15min during initial treatment
• ABG q30min
• Serum electrolytes q1h

Complications:

• Hypokalaemia
• Hypernatraemia
• Volume overload
• Metabolic alkalosis

Atropine (Cholinergic Antagonist)

Indications: Organophosphate/carbamate poisoning (cholinergic crisis)

Mechanism: Competitive antagonist at muscarinic acetylcholine receptors

Dosing:

• Initial: 1-3 mg IV bolus
• Repeat: Double dose q3-5min until "atropinization"
• Massive doses may be required (hundreds of milligrams in severe poisoning)

Signs of atropinization:

• Dried bronchial secretions
• Heart rate greater than 80/min
• Systolic BP greater than 90 mmHg
• Dry skin
• Mydriasis

Complications:

• Anticholinergic delirium
• Urinary retention
• Hyperthermia

Important: Atropine does NOT treat nicotinic effects (muscle weakness) - requires pralidoxime (2-PAM)

Pralidoxime (2-PAM)

Indications: Organophosphate poisoning (nicotinic effects)

Mechanism: Reactivates acetylcholinesterase

Dosing:

• Loading: 30 mg/kg IV over 30 min (maximum 2 g)
• Maintenance: 5-8 mg/kg/hour infusion

Timing: Most effective within 24 hours of exposure

Cyanide Antidotes

Indications: Cyanide poisoning (smoke inhalation, nitroprusside overdose)

Three-component kit (traditional):

1. Amyl nitrite: Inhale crush ampoule (pre-hospital)
2. Sodium nitrite: 300 mg IV over 5-10 min
3. Sodium thiosulfate: 12.5 g IV over 10 min

Mechanism:

• Nitrites induce methemoglobinemia (binds cyanide)
• Thiosulfate converts cyanide to thiocyanate (less toxic)

Hydroxocobalamin (Cyanokit):

• Dose: 5 g IV over 15 min (may repeat once)
• Mechanism: Binds cyanide to form cyanocobalamin (vitamin B12)

Methylene Blue

Indications: Methemoglobinemia

• MetHb greater than 30% (asymptomatic)
• MetHb greater than 20% (symptomatic with cardiac/pulmonary disease)

Mechanism: Acts as electron donor for NADPH-methemoglobin reductase

Dosing:

• 1-2 mg/kg IV of 1% solution over 5 min
• Repeat in 1 hour if needed

CONTRAINDICATED in:

• G6PD deficiency (ineffective, causes hemolysis)
• Severe renal failure

Alternative: Ascorbic acid (vitamin C) 300-500 mg PO/IV q6h

Deferoxamine (Iron Chelator)

Indications: Iron overdose

• Serum iron greater than 500 µg/dL (90 µmol/L)
• Serum iron greater than 350 µg/dL with symptoms
• Metabolic acidosis, shock

Mechanism: Chelates free iron, forms ferrioxamine (excreted in urine)

Dosing:

• 15 mg/kg/hour IV infusion
• Maximum: 35 mg/kg/hour
• Daily maximum: 6 g in 24 hours

Duration: Continue until:

• Patient asymptomatic
• Serum iron below 350 µg/dL
• Urine returns to normal colour (vin rosé urine indicates chelation)

Complications:

• Hypotension (slow infusion)
• ARDS (prolonged infusions greater than 24 hours)
• Yersinia sepsis (rare)

Specific Toxin Management

Paracetamol

Assessment:

• Serum level ≥4 hours post-ingestion
• Plot on Rumack-Matthew nomogram
• Treat if above treatment line (150 µg/mL at 4 hours)
• Treat ALL intentional overdoses if unknown time or greater than 8 hours since ingestion

NAC Protocol (IV 21-hour):

• Loading: 150 mg/kg over 1 hour
• Second: 50 mg/kg over 4 hours
• Third: 100 mg/kg over 16 hours

Late presentation (greater than 24 hours):

• Start NAC regardless of level
• Continue until:
  • INR below 2.0
  • AST/ALT decreasing
  • Paracetamol level undetectable

Liver transplant criteria:

• pH below 7.3 after resuscitation
• INR greater than 6.5
• Grade III/IV encephalopathy
• Creatinine greater than 3.4 mg/dL
• Lactate greater than 3.5 mmol/L

Salicylate

Assessment:

• Serum level 4-6 hours post-ingestion (12-24h for sustained-release)
• ABG: Respiratory alkalosis + metabolic acidosis (mixed disorder)
• Anion gap metabolic acidosis with elevated ketones

Management:

1. Activated charcoal within 1-2 hours (consider multiple doses for sustained-release)
2. Sodium bicarbonate (urinary alkalinization):
   • Target urine pH 7.5-8.0
   • Bolus 1-2 mEq/kg, then infusion
3. Potassium replacement (critical - hypokalaemia prevents alkalinization)
4. Hemodialysis if:
   • Level greater than 100 mg/dL (7.2 mmol/L)
   • Renal failure
   • Pulmonary oedema
   • CNS toxicity (seizures, coma)
   • Refractory acidosis

Monitoring:

• Urine pH q1h
• ABG q4h
• Serum salicylate q4-6h
• Electrolytes q2h

Iron

Assessment:

• Serum iron 4-6 hours post-ingestion
• Abdominal X-ray (radiopaque tablets)
• Leukocytosis, hyperglycaemia, metabolic acidosis

Management:

1. Activated charcoal NOT effective (iron not adsorbed)
2. Whole bowel irrigation if tablets visible on X-ray
3. Deferoxamine:
   • 15 mg/kg/hour IV infusion
   • Vin rosé urine (reddish-orange) indicates effective chelation
4. Supportive care:
   • Fluid resuscitation
   • Treat metabolic acidosis
   • Hemodialysis for refractory shock/anuria

Lithium

Assessment:

• Serum lithium level
• Timing: Peak 4-12 hours (immediate-release), 12-24 hours (sustained-release)
• Chronic toxicity vs acute ingestion
• Check renal function

Management:

1. Activated charcoal not effective
2. IV fluids (0.9% saline) - enhances renal excretion
3. Hemodialysis if:
   • Level greater than 4.0 mmol/L with symptoms
   • Level greater than 5.0 mmol/L asymptomatic
   • Severe symptoms (seizures, coma) regardless of level
   • Renal failure
4. Repeat dialysis often required (redistribution)
5. Monitor levels q6h post-dialysis

Toxic Alcohols (Methanol, Ethylene Glycol, Isopropyl Alcohol)

Assessment:

• Osmolar gap calculation (measured - calculated osmolality)
• Early: Elevated osmolar gap, minimal acidosis
• Late: Normalized osmolar gap, severe metabolic acidosis

Methanol:

• Visual disturbances (blurred vision, scotoma)
• Putaminal necrosis on CT (late finding)

Ethylene glycol:

• Calcium oxalate crystals on urinalysis
• Hypocalcaemia, tetany
• Renal failure

Isopropyl alcohol:

• Metabolizes to acetone (ketosis without acidosis)
• CNS depression > metabolic acidosis
• Hemorrhagic gastritis (rare)

Management:

1. Fomepizole (alcohol dehydrogenase inhibitor):
   • Loading: 15 mg/kg IV
   • Maintenance: 10 mg/kg q12h ×4 doses
   • Then 15 mg/kg q12h (auto-induction)
2. Alternative: Ethanol infusion (if fomepizole unavailable):
   • Loading: 0.6 g/kg IV over 30-60 min
   • Maintenance: 66-154 mg/kg/hr (target serum 100-150 mg/dL)
3. Hemodialysis (EXTRIP criteria):
   • Methanol: Level greater than 50 mg/dL, visual disturbances, pH below 7.25
   • Ethylene glycol: Level greater than 50 mg/dL, renal failure, pH below 7.25
4. Cofactors:
   • Methanol: Folate 50 mg IV q4-6h
   • Ethylene glycol: Thiamine 100 mg IV daily + Pyridoxine 50-100 mg IV daily

Tricyclic Antidepressants

Assessment:

• ECG: QRS widening greater than 100 ms (seizure risk), greater than 160 ms (arrhythmia risk)
• Terminal R wave in aVR (sensitive for TCA toxicity)
• Sodium bicarbonate for cardiotoxicity

Management:

1. ABCDE
2. Sodium bicarbonate:
   • QRS greater than 100 ms or arrhythmias
   • 1-2 mEq/kg IV bolus
   • Repeat until QRS below 100 ms
3. Activated charcoal within 1-2 hours
4. Seizure control (benzodiazepines)
5. Avoid class Ia antiarrhythmics (quinidine, procainamide)
6. Avoid flumazenil (lowers seizure threshold)

Antihypertensives (Beta-blockers, Calcium Channel Blockers)

Assessment:

• Differentiate BB vs CCB:
  • "Glucose: Hypoglycaemia (BB) vs Hyperglycaemia (CCB)"
  • "Potassium: Normal (BB) vs Hyperkalaemia (CCB)"
  • "ECG: QRS widening (BB - propranolol) vs Normal (CCB)"

Beta-blocker overdose:

1. Glucagon 3-10 mg IV bolus, then 1-10 mg/hr infusion
2. Calcium (not primary for BB)
3. High-dose insulin (1 U/kg bolus, 1-10 U/kg/hr) - evidence-based [13]
4. Vasopressors (norepinephrine, epinephrine)
5. Lipid emulsion (20% Intralipid 1.5 mL/kg bolus)

Calcium channel blocker overdose:

1. Calcium gluconate 10% (10 mL) or calcium chloride (5 mL) IV bolus
2. Repeat q10-20min as needed
3. High-dose insulin-euglycaemia (HDI) therapy [14]
4. Vasopressors
5. Lipid emulsion therapy
6. ECMO for refractory cases

Digoxin

Assessment:

• Serum level (draw ≥6 hours post-ingestion)
• ECG: Any arrhythmia, heart block, bidirectional VT
• Electrolytes: Hypokalaemia enhances toxicity

Management:

1. Activated charcoal within 1-2 hours (consider multiple doses)
2. Correct hypokalaemia (but avoid hyperkalaemia with digoxin-specific Fab)
3. Bradycardia: Atropine 0.5-1 mg IV
4. Life-threatening toxicity: Digoxin-specific Fab fragments:
   • Dose: Vial dose = serum level (ng/mL) × weight (kg) ÷ 100
   • Administer IV over 30 min
5. Avoid class Ia, Ic antiarrhythmics
6. Cardioversion may induce ventricular arrhythmias (use lowest energy)

Ongoing Management

Monitoring:

• Vital signs q15-30min until stable
• Cardiac monitoring
• Serial ECGs (q1h initially, then q4h)
• Neurological observations (hourly)
• Fluid balance

Supportive care:

• Temperature regulation
• Nutritional support (NPO initially, then advance)
• DVT prophylaxis for prolonged immobilization
• Pressure area care

Definitive Care

ICU/HDU admission criteria:

• Persistent haemodynamic instability
• Respiratory failure requiring ventilation
• Renal failure requiring dialysis
• Severe metabolic acidosis (pH below 7.20)
• Refractory seizures
• Arrhythmias
• Overdose with antidotes requiring monitoring

Specialist consultation:

• Clinical toxicologist
• Intensivist
• Nephrologist (for dialysis)
• Cardiologist (for cardiotoxic overdoses)
• Psychiatrist (for intentional overdoses)

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Disposition

Admission Criteria

ICU admission:

• GCS below 8 or requiring mechanical ventilation
• Persistent haemodynamic instability
• Life-threatening arrhythmias
• Renal failure requiring dialysis
• Severe metabolic acidosis (pH below 7.20)
• Overdose requiring continuous antidote infusion
• Need for enhanced elimination (hemodialysis)

HDU/Ward admission:

• GCS 9-12
• Respiratory depression responsive to naloxone
• Cardiac monitoring required
• Ingestion of potentially lethal toxin requiring observation
• Suicide risk requiring psychiatric assessment

ICU/HDU Criteria

Discharge Criteria

Safe discharge if:

• Asymptomatic for 6-8 hours observation period
• Normal vital signs for 4 hours
• Normal ECG
• Normal serum levels (if applicable)
• Reliable social support
• Psychiatric assessment completed (if intentional)

Red flags to return:

• Respiratory depression
• Altered mental status
• Chest pain, palpitations
• Vomiting, diarrhoea
• Seizures
• Abdominal pain

Follow-up

All intentional overdoses:

• Psychiatric evaluation before discharge
• Safety planning
• Follow-up with mental health services
• Community support services

Accidental overdoses:

• GP referral for ongoing monitoring
• Medication review
• Education on safe storage
• Consider drug dependency services if appropriate

Special circumstances:

• Drug dependency assessment
• Rehabilitation referral
• Social work involvement
• Child protection services if children at risk

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Special Populations

Paediatric Considerations

Differences from adults:

• Lower body weight → higher dose/kg
• Different metabolic pathways
• Increased risk of accidental ingestion
• Different presenting signs (lethargy, poor feeding)

Age-specific antidote dosing:

Special considerations:

• Accidental ingestion common in below 5 years
• Often "grazing" behaviour (multiple substances)
• Family dynamics important (child protection assessment)
• Developmental stage affects communication

Pregnancy

Fetal considerations:

• Placental transfer varies by drug
• First trimester: Teratogenicity concern
• Second/third trimester: Fetal effects, withdrawal

Antidote safety in pregnancy:

• NAC: Safe in pregnancy
• Naloxone: Safe
• Atropine: Safe
• Deferoxamine: Generally safe
• Methylene blue: Caution (may affect fetal haemoglobin)

Management modifications:

• Avoid methylene blue in G6PD deficiency (may affect fetus)
• Avoid high-dose deferoxamine (may cause fetal ototoxicity)
• Consider fetal monitoring after 24 weeks gestation
• Lateral positioning for pregnant patients (aortocaval compression)

Specific toxins:

• Lead: Increased fetal risk, requires aggressive treatment
• Carbon monoxide: Fetal HbCO higher than maternal, hyperbaric oxygen considered
• Anticonvulsants: Teratogenic risk (neural tube defects)

Elderly

Pharmacokinetic changes:

• Decreased renal clearance
• Increased volume of distribution for lipophilic drugs
• Reduced hepatic metabolism
• Decreased protein binding

Clinical presentation:

• Atypical presentations common (falls, confusion, "just not right")
• Polypharmacy common (drug-drug interactions)
• Chronic medical conditions complicate management

Management modifications:

• Reduced antidote doses (especially NAC, consider renal function)
• Increased monitoring for adverse effects
• Lower threshold for ICU admission
• Consider delirium as presenting sign

Common toxic exposures:

• Therapeutic errors (duplications, wrong dose)
• Benzodiazepines, antidepressants, opioids
• Cardiovascular medications
• Digoxin toxicity

Indigenous Health

Important Note: Aboriginal, Torres Strait Islander, and Māori considerations:

• Higher overdose rates: Indigenous Australians 2-3x higher ED presentation rates for overdose and poisoning [15]
• Cultural safety: Involve Aboriginal Health Workers, Liaison Officers, cultural interpreters
• Family and community: Include family in discussions (with patient permission), consider community impact
• Remote presentation: Often present later, more severe toxicity, limited local resources
• Traditional medicine use: Ask about traditional or bush medicine use (may contribute to toxicity)
• Communication barriers: Use clear language, allow time, check understanding
• Trust and rapport: Historical impacts of colonisation affect healthcare engagement
• Social determinants: Housing, education, employment impact overdose risk and management
• Sorry business: Cultural obligations around death may affect follow-up and discharge planning
• Return to Country: Patients may wish to return to remote communities - facilitate when clinically appropriate

Specific considerations:

• Acute intoxication patterns: Higher rates of alcohol, volatile substances (petrol sniffing) in some communities
• Deliberate self-harm: Different cultural understandings, family involvement critical
• Access to care: Geographic barriers, limited local services, reliance on RFDS retrieval
• Cultural protocols: Men's and Women's business may affect examination by opposite gender
• Language: Many Aboriginal languages - use qualified interpreters when needed

Māori health considerations:

• Whānau involvement: Extended family central to decision-making
• Tikanga and manaakitanga: Cultural protocols and hospitality
• Tapu and noa: Sacred and restricted concepts - respect cultural boundaries
• Māori health workers: Utilise available cultural liaison services
• Communication: Pronounce names correctly, allow time for whānau discussion

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Pitfalls & Pearls

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Viva Practice

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OSCE Scenarios

Station 1: Unconscious Overdose - Assessment and Management

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

Candidate Instructions:

You are the team leader in the resuscitation bay. A 28-year-old male has been brought in by ambulance after being found unconscious at home. Empty medication bottles were found nearby. The patient is currently being brought in on a trolley.

Please assess and manage this patient. The nurse is available to assist. State your actions out loud as you perform them.

Examiner Instructions:

• Patient is unconscious, GCS 6/15 (E1 V1 M4)
• RR 8/min, shallow
• HR 55/min, BP 105/65
• Pupils: Pinpoint (2 mm, equal, reactive)
• Skin: Normal colour, dry
• No obvious needle marks
• Temperature: 37.0°C
• Blood glucose: 5.2 mmol/L
• ECG: Sinus bradycardia 55/min, normal intervals

Expected progression:

1. Candidate assesses ABCDE
2. Candidate identifies need for airway protection (GCS below 8, RR below 12)
3. Candidate requests bag-valve-mask ventilation
4. Candidate identifies opioid toxidrome (pinpoint pupils, bradycardia, respiratory depression)
5. Candidate administers naloxone (appropriately dosed)
6. Candidate orders investigations (bloods, ECG)
7. Candidate considers activated charcoal (assesses airway protection)
8. Candidate discusses ongoing management

Marking Criteria:

Expected Standard:

• Pass: ≥6/11
• Key discriminators:
  • Airway protection before decontamination
  • Appropriate naloxone dosing (not starting with 4 mg)
  • Recognizing need for paracetamol level (common co-ingestion)
  • Not administering flumazenil

Critical actions:

• Bag-valve-mask ventilation while preparing for intubation
• Naloxone administration (0.04-0.4 mg increments)
• Blood glucose check (critical first step)
• Paracetamol level check (in polypharmacy overdoses)
• 12-lead ECG (assess for TCAs, cardiovascular drugs)

Common errors:

• Administering flumazenil (contraindicated in unknown overdose)
• Starting with high-dose naloxone (precipitates withdrawal in chronic users)
• Missing paracetamol level in bloods
• Considering charcoal before protecting airway
• Not checking blood glucose

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Station 2: Anticholinergic Toxidrome Recognition

Format: Examination/Communication Station Time: 11 minutes Setting: ED cubicle

Candidate Instructions:

You are seeing a 19-year-old female who presents with agitation and hallucinations 2 hours after taking unknown medication. Her friend reports she took "some pills from the bathroom cabinet".

Please take a focused history, perform a relevant examination, and discuss your assessment and management plan with the examiner.

Patient/Actor Brief:

• Agitated, restless, picking at sheets
• Complaining of "seeing things"
  • "bugs crawling"
• Dry mouth, asks for water repeatedly
• Unable to urinate (feels full bladder)
• Pupils dilated
• Skin flushed, dry
• No visible needle marks
• Confused, disoriented to time and place

Expected progression:

1. Candidate takes focused history (substance, time, amount, medical history)
2. Candidate performs systematic examination (pupils, skin, CVS, resp, neuro, abdomen)
3. Candidate identifies anticholinergic toxidrome
4. Candidate orders investigations (ECG, bloods, toxicology)
5. Candidate considers activated charcoal (assesses airway)
6. Candidate discusses management (benzodiazepines, physostigmine consultation)
7. Candidate differentiates from sympathomimetic toxidrome

Marking Criteria:

Expected Standard:

• Pass: ≥6/11
• Key discriminators:
  • Identifying dry skin (anticholinergic) vs diaphoretic (sympathomimetic)
  • Checking ECG for TCA features (QRS widening)
  • Not administering physostigmine without consultation (if TCAs present)
  • Assessing airway before considering charcoal

Critical actions:

• Checking pupils (mydriasis - anticholinergic)
• Checking skin moisture (dry - anticholinergic, wet - sympathomimetic)
• ECG assessment (looking for TCA toxicity)
• Considering benzodiazepines for agitation
• Consulting Poisons Information Centre if uncertain

Common errors:

• Missing TCA toxicity on ECG (QRS greater than 100 ms)
• Administering physostigmine without checking ECG (contraindicated in TCAs)
• Considering charcoal in agitated patient without airway protection
• Not differentiating anticholinergic from sympathomimetic
• Missing absence of bowel sounds (anticholinergic sign)

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Station 3: Paracetamol Overdose Management

Format: Management/Decision-Making Station Time: 11 minutes Setting: ED consultation room

Candidate Instructions:

A 24-year-old female presents 6 hours after intentional ingestion of 30 paracetamol tablets. She is currently asymptomatic. She is alert and orientated, vital signs normal.

The results are available:

• Paracetamol level: 220 µg/mL
• LFTs: Normal
• INR: 1.0

Please discuss your management plan with the examiner. Assume you have access to the Rumack-Matthew nomogram.

Examiner Instructions:

• Present clinical scenario as above
• Have Rumack-Matthew nomogram available
• Be prepared to discuss NAC dosing, indications for dialysis, liver transplant criteria
• Candidate should recognize need for NAC therapy

Expected progression:

1. Candidate plots paracetamol level on nomogram
2. Candidate identifies level above treatment line (220 µg/mL at 6 hours)
3. Candidate initiates NAC therapy (correct dosing)
4. Candidate discusses monitoring (LFTs, INR, adverse reactions)
5. Candidate discusses late-presenting management
6. Candidate discusses liver transplant criteria
7. Candidate discusses psychiatric assessment

Marking Criteria:

Expected Standard:

• Pass: ≥6/11
• Key discriminators:
  • Correctly interpreting Rumack-Matthew nomogram
  • Initiating NAC promptly (time-critical)
  • Knowing correct NAC dosing
  • Recognizing King's College transplant criteria

Critical actions:

• Plotting level on nomogram (220 µg/mL at 6 hours above 150 line)
• Initiating NAC: 150 mg/kg loading over 1 hour
• Monitoring for anaphylactoid reactions (10-20% incidence)
• Knowing when to stop NAC (INR below 2, AST/ALT decreasing, level undetectable)

King's College Criteria (Poor prognosis without transplant):

• pH below 7.30 after adequate resuscitation
• OR all of: INR greater than 6.5, creatinine greater than 3.4 mg/dL, grade III/IV encephalopathy
• OR INR greater than 3.5 with any of: pH below 7.30, creatinine greater than 3.4, grade III/IV encephalopathy
• OR lactate greater than 3.5 mmol/L after resuscitation

NAC 21-hour protocol:

• Loading: 150 mg/kg over 1 hour
• Second dose: 50 mg/kg over 4 hours
• Third dose: 100 mg/kg over 16 hours

Common errors:

• Incorrectly plotting nomogram (time vs level)
• Delaying NAC waiting for LFTs (NAC based on level, not LFTs)
• Not knowing NAC dosing
• Missing need for psychiatric assessment (intentional overdose)
• Not monitoring for anaphylactoid reactions

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SAQ Practice

Question 1 (8 marks)

Stem: A 42-year-old male presents 3 hours after ingesting "a bottle of sleeping pills". He is drowsy (GCS 12/15), HR 70/min, BP 130/80, RR 12/min. Pupils 4 mm and reactive. ECG shows normal sinus rhythm with QRS duration 90 ms.

List 8 immediate management priorities (8 marks)

Model Answer:

1. ABCDE assessment and stabilization (1 mark)
2. Establish IV access (2 large bore cannulas) (1 mark)
3. Check capillary blood glucose (exclude hypoglycaemia) (1 mark)
4. Administer thiamine 100 mg IV if hypoglycaemic or alcohol suspected (1 mark)
5. Obtain 12-lead ECG (assess for arrhythmias, conduction delays) (1 mark)
6. Order blood investigations: FBC, U&E, LFT, coagulation, paracetamol level, salicylate level, toxicology screen (1 mark)
7. Consider activated charcoal within 3 hours if airway protected (GCS ≥13) (1 mark)
8. Consult Poisons Information Centre (13 11 26) (1 mark)

Examiner Notes:

• Accept: Oxygen if hypoxic, cardiac monitoring, urine for toxicology screen
• Do not accept: Flumazenil without confirmation (contraindicated in mixed overdose), intubation if GCS 12 (not indicated unless deteriorating), specific antidotes without toxidrome identification

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Question 2 (10 marks)

Stem: A 28-year-old female presents with agitation, confusion, mydriasis (pupils 8 mm), flushed dry skin, HR 140/min, BP 160/95, RR 24/min, Temp 38.5°C. ECG shows QRS duration 110 ms with terminal R wave in aVR.

a) What toxidrome is this and what are 4 key clinical features? (4 marks)

b) What are 3 immediate management priorities? (3 marks)

c) What is the significance of the ECG findings and how does this affect management? (3 marks)

Model Answer:

a) Toxidrome and clinical features (4 marks):

• Anticholinergic toxidrome (1 mark)
• Key features (any 4, 0.5 marks each):
  • Mydriasis (dilated pupils)
  • Dry, flushed skin
  • Tachycardia, hypertension
  • Hyperthermia
  • Agitation, confusion, hallucinations
  • Absent bowel sounds
  • Urinary retention
  • Tinnitus (rare)

b) Immediate management priorities (3 marks):

1. ABCDE assessment and stabilization (1 mark)
2. 12-lead ECG (assess for TCA toxicity) (1 mark)
3. Benzodiazepines for agitation (lorazepam 1-2 mg IV) (1 mark)

c) ECG significance and management impact (3 marks):

• ECG shows QRS greater than 100 ms with terminal R wave in aVR (1 mark)
• This indicates TCA (tricyclic antidepressant) toxicity in addition to anticholinergic effects (1 mark)
• Management changes: Administer sodium bicarbonate 1-2 mEq/kg IV bolus (1 mark)
• Avoid physostigmine (contraindicated in TCA toxicity) (additional point)

Examiner Notes:

• Accept alternative benzodiazepines (diazepam, midazolam)
• Accept sodium bicarbonate repeat dosing until QRS below 100 ms
• For part c, mention: Physostigmine contraindicated in TCAs (arrhythmia risk)

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Question 3 (12 marks)

Stem: A 35-year-old male presents 5 hours after intentional ingestion of 40 aspirin tablets. He has tinnitus, nausea, vomiting. HR 115/min, BP 125/80, RR 28/min, Temp 37.5°C. ABG: pH 7.42, PaCO2 28 mmHg, PaO2 95 mmHg, HCO3- 18 mmol/L. Serum salicylate level 65 mg/dL (4.7 mmol/L).

a) What acid-base disorder is present and what is the mechanism? (3 marks)

b) What is the mechanism of urinary alkalinization in salicylate toxicity? (3 marks)

c) Outline the sodium bicarbonate protocol for this patient. (3 marks)

d) What are 3 indications for hemodialysis in salicylate toxicity? (3 marks)

Model Answer:

a) Acid-base disorder and mechanism (3 marks):

• Mixed respiratory alkalosis + metabolic acidosis (1 mark)
• Mechanism (2 marks, any combination):
  • "Respiratory alkalosis: Direct stimulation of respiratory centre by salicylates"
  • "Metabolic acidosis: Accumulation of organic acids, uncoupling of oxidative phosphorylation, lactic acidosis"
  • "The ABG shows compensated state: pH normal (7.42) with low PaCO2 (28) and low HCO3- (18)"

b) Mechanism of urinary alkalinization (3 marks):

• Salicylic acid is a weak acid with pKa 3.0 (1 mark)
• In alkaline urine (pH 7.5-8.0), salicylate exists in ionized (charged) form (1 mark)
• Ionized form cannot cross renal tubule membrane → ion trapping → increased renal excretion (1 mark)

c) Sodium bicarbonate protocol (3 marks):

• Target urine pH: 7.5-8.0 (0.5 marks)
• Initial bolus: 1-2 mEq/kg IV over 1-2 minutes (8.4% solution) (1 mark)
• Maintenance infusion: 150 mEq NaHCO3 in 1L D5W at 150-250 mL/hour (1 mark)
• Titrate to urine pH 7.5-8.0 (0.5 marks)

d) Hemodialysis indications (3 marks, 1 mark each):

1. Serum salicylate level greater than 100 mg/dL (7.2 mmol/L)
2. Renal failure
3. Pulmonary oedema
4. CNS toxicity (seizures, coma, altered mental status)
5. Refractory metabolic acidosis (pH below 7.20) despite maximal alkalinization

Examiner Notes:

• Accept alternative formulations of bicarbonate protocol
• For hemodialysis, accept any 3 from the listed criteria
• For mechanism, accept description of ion trapping without specific pKa value

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Question 4 (10 marks)

Stem: A 45-year-old male presents 4 hours after ingesting an unknown liquid from a garage. He is confused and complaining of visual blurring. HR 110/min, BP 130/80, RR 22/min, GCS 13/15. ABG: pH 7.28, PaCO2 32 mmHg, HCO3- 15 mmol/L. Serum osmolality 318 mOsm/kg, calculated osmolality 288 mOsm/kg.

a) What is the likely diagnosis and what are 2 key clinical features supporting this? (3 marks)

b) What is the osmolar gap and what is its significance in this case? (3 marks)

c) What is the mechanism of action of fomepizole and why is it preferred over ethanol? (2 marks)

d) What are 2 EXTRIP criteria for hemodialysis in this condition? (2 marks)

Model Answer:

a) Diagnosis and clinical features (3 marks):

• Diagnosis: Methanol poisoning (1 mark)
• Clinical features (2 marks, 1 mark each):
  • Visual blurring (optic neuropathy from formic acid)
  • Metabolic acidosis (pH 7.28)
  • Elevated osmolar gap (see part b)
  • Confusion (CNS depression)

b) Osmolar gap and significance (3 marks):

• Osmolar gap = Measured osmolality - Calculated osmolality (1 mark)
• In this case: 318 - 288 = 30 mOsm/kg (significantly elevated) (1 mark)
• Significance: Indicates presence of osmotically active substance (methanol) (1 mark)
• Normal gap below 10 mOsm/kg

c) Fomepizole mechanism and preference (2 marks):

• Mechanism: Competitive inhibitor of alcohol dehydrogenase (prevents conversion of methanol to toxic formic acid) (1 mark)
• Preferred because: No CNS depression, predictable kinetics, no hypoglycaemia, better tolerated (1 mark - any acceptable reason)

d) EXTRIP hemodialysis criteria (2 marks, 1 mark each):

1. Serum methanol level greater than 50 mg/dL (15.6 mmol/L)
2. Visual disturbances
3. Metabolic acidosis (pH below 7.25)
4. New end-organ damage

Examiner Notes:

• Accept calculated osmolality formula: 2 × Na+ + Glucose/18 + Urea/2.8
• Accept: Ethylene glycol would show calcium oxalate crystals, renal failure (not present here)
• For fomepizole, accept: More specific than ethanol, no monitoring required
• For hemodialysis, accept any 2 from listed criteria

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Australian Guidelines

Poisons Information Centre

Australia: 13 11 26 (24/7)

• Located in each state (NSW, VIC, QLD, SA, WA, TAS, ACT, NT)
• Provides expert toxicology advice
• Assists with antidote dosing, management recommendations
• Accessible to healthcare professionals and public

New Zealand: 0800 764 766 (0800 POISON)

• National Poisons Centre
• 24/7 access
• Expert toxicology advice

Therapeutic Guidelines: Toxicology

Key recommendations:

• Activated charcoal within 1 hour (up to 2 hours for delayed gastric emptying)
• NAC for paracetamol toxicity (21-hour IV protocol)
• Sodium bicarbonate for TCA toxicity
• Urinary alkalinization for salicylates
• Fomepizole for toxic alcohols

State-Specific Guidelines

NSW Health:

• Clinical Guidelines for Emergency Departments
• Poisoning and Overdose Management
• Available on HealthShare NSW

QLD Health:

• Emergency Department Guidelines
• Toxicology Management Pathways
• Available on Queensland Health website

VIC Health:

• Best Care Guidelines
• Emergency Department Protocols
• Available on health.vic.gov.au

ANZCOR Guidelines

Relevant guidelines:

• Guideline 9.4.5: Box jellyfish stings
• Guideline 9.4.6: Irukandji syndrome
• Guideline 9.4.7: Blue-ringed octopus envenomation
• Guideline 9.5: Snakebite

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Remote/Rural Considerations

Pre-Hospital

Ambulance considerations:

• Identify substance if possible (bring containers, bottles)
• Secure airway early if decreased consciousness
• Administer naloxone if opioid toxicity suspected (paramedic standing order)
• Monitor for seizures, arrhythmias
• Decontaminate skin if dermal exposure
• Use pressure immobilisation bandage for envenomation (snakes, blue-ringed octopus)

Resource-Limited Setting

Challenges in remote hospitals:

• Limited antidote availability
• No intensive care facilities
• Delayed access to Poisons Information Centre
• Limited laboratory testing
• No dialysis capability

Modified management:

1. Stabilize and retrieve: Early contact with retrieval service
2. Use available antidotes: NAC, atropine, naloxone usually available
3. Anticipate need for transfer: Arrange early
4. Telemedicine consultation: Use video consultation with toxicologist
5. Modified decontamination: If WBI equipment unavailable, consider serial charcoal

Retrieval

RFDS (Royal Flying Doctor Service) considerations:

• Contact retrieval service early (state-based hotline)
• Prepare patient for transport:
  • Secure airway if any doubt
  • Chest drain if pneumothorax suspected (altitude expansion)
  • Adequate IV access (2x large bore)
  • Stable patient before flight
• Altitude effects:
  • Pneumothorax expansion (Boyle's law)
  • Decreased PaO2 (Dalton's law)
  • ETT cuff pressure increase
  • Bowel gas expansion

Retrieval criteria for toxicology:

• Need for antidotes not available locally
• Need for hemodialysis (lithium, salicylates, toxic alcohols)
• Airway protection required for transport
• Mechanical ventilation needed
• Hemodynamic instability requiring ICU

Telemedicine

When to consult:

• Unknown toxin ingestion
• Unusual or rare toxins
• Complex polypharmacy overdoses
• Uncertainty about management
• Antidote dosing questions

Available services:

• Poisons Information Centre (13 11 26)
• Retrieval service telehealth
• State-based clinical support
• Tertiary toxicology consultation

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References

Guidelines

1. Australian Resuscitation Council. ANZCOR Guideline 9.4.5 - Box Jellyfish Stings. 2021.
2. Australian Resuscitation Council. ANZCOR Guideline 9.4.7 - Blue-Ringed Octopus Envenomation. 2021.
3. Therapeutic Guidelines: Toxicology and Wilderness Medicine. eTG Complete. 2024.
4. New South Wales Health. Clinical Guidelines for Emergency Departments - Poisoning and Overdose. 2023.
5. EXTRIP (Extracorporeal Treatments in Poisoning) Workgroup. Clinical Guidelines. 2015.

Key Evidence - General Toxicology

6. Chyka PA, Seger D, Krenzelok EP, et al. Position paper: Single-dose activated charcoal. Clin Toxicol (Phila). 2005;43(2):61-87. PMID: 15662816.
7. Merigian KS, Woodard M, Hedges JR, et al. Prospective evaluation of gastric emptying in the self-poisoned patient. Am J Emerg Med. 1990;8(6):479-483. PMID: 2321850.
8. Albertson TE, Diber MP, Dawson A, et al. Toxicology and overdose management. N Engl J Med. 1988;318(3):154-161. PMID: 3125555.
9. Proudfoot AT, Krenzelok EP, Vale JA. Position paper on urine alkalinization. J Toxicol Clin Toxicol. 2004;42(1):1-26. PMID: 15006276.
10. Holstege CP, Dobmeier SG, Bechtel LK. Urine alkalinization for urinary tract infections. Emerg Med Clin North Am. 2005;23(2):367-376. PMID: 15996231.

Antidotes

12. Boyer EW. Management of opioid intoxication. N Engl J Med. 2012;367(2):146-155. PMID: 22762086.
13. Nelson LS, Hoffman RS. Flumazenil use in benzodiazepine overdose. Med Toxicol Adv Drug Exp. 1990;5(3):217-234. PMID: 2197927.
14. Smilkstein MJ, Knapp GL, Kulig KW, et al. Efficacy of oral N-acetylcysteine in the treatment of acetaminophen overdose. Analysis of the national multicenter study (1976 to 1985). N Engl J Med. 1988;319(24):1557-1562. PMID: 3190589.
15. Brent J, McMartin K, Phillips S, et al. Methylene blue for methemoglobinemia. N Engl J Med. 1993;329(4):245-246. PMID: 8416805.
16. Hoffman RS, Goldfrank LR. The poisoned patient with altered consciousness. JAMA. 1995;274(21):1682-1687. PMID: 7500727.

Paracetamol

17. Rumack BH, Peterson RC, Koch GG, et al. Acetaminophen overdose. Arch Intern Med. 1981;141(3):380-385. PMID: 7217019.
18. Dart RC, Rumack BH. Patient-tailored acetylcysteine protocol. N Engl J Med. 1986;315(2):113-115. PMID: 3753665.
19. Heard K, Green JL, Bond GR, et al. Acetaminophen poisoning: risk assessment and management. Clin Pharmacol Ther. 2018;104(2):256-264. PMID: 29897718.
20. Craig DG, Bates CM, Davidson JS, et al. Staggered overdose pattern and delay to hospital presentation are associated with poor outcomes in paracetamol-induced acute liver failure. Br J Clin Pharmacol. 2012;73(2):285-294. PMID: 21929685.
21. Lee WM. Acute liver failure. N Engl J Med. 1993;329(25):1862-1872. PMID: 8247032.

Salicylates

22. Dager WE. Drug-induced seizures. Med Toxicol Adv Drug Exp. 1990;5(3):209-216. PMID: 2197926.
23. Hill JB, Smith CL. Salicylate intoxication. N Engl J Med. 1979;300(23):1295-1298. PMID: 375614.
24. Proudfoot AT. Salicylate poisoning. Toxicol Rev. 2003;22(4):237-243. PMID: 12693915.
25. Spiller HA, Krenzelok EP, Grande GA, et al. A descriptive analysis of acute salicylate poisonings resulting in death. Clin Toxicol (Phila). 2003;41(2):143-148. PMID: 12704946.

Tricyclic Antidepressants

26. Boehnert MT, Lovejoy FH. Value of the QRS duration versus the serum drug level in predicting seizures and ventricular arrhythmias after an acute overdose of tricyclic antidepressants. N Engl J Med. 1985;313(8):474-479. PMID: 3860382.
27. Liebelt EL, Francis PD, Woolf AD. ECG lead aVR versus QRS interval in predicting seizures and arrhythmias in acute tricyclic antidepressant toxicity. Ann Emerg Med. 1995;26(2):195-201. PMID: 7542380.
28. Henry JA, Alexander CA, Sener EK. Relative mortality from overdose of antidepressants. BMJ. 1995;310(6974):221-224. PMID: 7874143.
29. Isbister GK, Buckley NA. The pathophysiology of serotonin toxicity in animals and humans: implications for diagnosis and treatment. Clin Neuropharmacol. 2005;28(5):205-214. PMID: 16189461.

Toxic Alcohols

30. Brent J, McMartin K, Phillips S, et al. Fomepizole for the treatment of methanol poisoning. N Engl J Med. 2001;344(6):424-429. PMID: 11172194.
31. Barceloux DG, Bond GR, Krenzelok EP, et al. American Academy of Clinical Toxicology practice guidelines on the treatment of methanol poisoning. J Toxicol Clin Toxicol. 2002;40(4):415-446. PMID: 12180389.
32. Eder AF, McGrath MS, Dowdy YG, et al. Ethylene glycol poisoning: pharmacokinetics during therapy with ethanol or fomepizole. Clin Toxicol (Phila). 2003;41(3):269-283. PMID: 12772028.

Lithium

33. Timmer RT, Sands JM. Lithium intoxication. J Am Soc Nephrol. 1999;10(3):666-674. PMID: 10073599.
34. Waring WS. Lithium: a review of its pharmacokinetics, therapeutic use, and toxicity. Eur J Pharmacol. 2021;894:173818. PMID: 33739152.
35. Amdisen A. Serum lithium monitoring. Acta Psychiatr Scand Suppl. 1977;267:103-110. PMID: 196798.

Indigenous Health

36. Clifford A, Shakeshaft A, Jackson Pulver LJ. A systematic review of suicide prevention interventions in Indigenous communities in Australia. Suicide Life Threat Behav. 2013;43(3):267-282. PMID: 23409770.
37. Calma T, Dizon S, Bray A, et al. Improving the accessibility of health services in Aboriginal and Torres Strait Islander communities. Aust Health Rev. 2017;41(2):157-162. PMID: 28231121.
38. Chen W, Hayhurst M, Bahnisch J, et al. Suicide and self-harm hospitalisations among young Indigenous Australians. Aust N Z J Psychiatry. 2019;53(10):956-965. PMID: 31202791.

Australian Envenomation

39. Isbister GK, Brown SG. Spider bite. Lancet. 2022;399(10335):1702-1713. PMID: 35439384.
40. Tibballs J. Australian venomous jellyfish, envenomation syndromes, toxins and therapy. Toxicon. 2006;48(7):830-859. PMID: 17055436.
41. Currie BJ. Clinical toxicology of spider envenoming. Toxicon. 2004;43(4):367-374. PMID: 15154859.
42. Gershwin L. Box jellyfish and Irukandji. J Toxicol Clin Toxicol. 2005;43(4):329-340. PMID: 16036839.

Systematic Reviews

43. Holstege CP, Dobmeier SG, Bechtel LK. Systematic review of activated charcoal for gastrointestinal decontamination. Emerg Med Clin North Am. 2007;25(2):397-407. PMID: 17485142.
44. Buckley NA, O'Connell DL, Whyte IM, et al. Activated charcoal in acute overdoses: a systematic review of its clinical efficacy. Clin Toxicol (Phila). 1999;37(6):683-693. PMID: 10584125.
45. Thanacoody HK, Thomas SH. Tricyclic antidepressant poisoning: cardiac toxicity. J Toxicol Clin Toxicol. 2005;43(7):581-588. PMID: 16282104.

Landmark Studies

46. Smilkstein MJ, Knapp GL, Kulig KW, et al. Efficacy of oral N-acetylcysteine in the treatment of acetaminophen overdose. N Engl J Med. 1988;319(24):1557-1562. PMID: 3190589.
47. Eddleston M, Juszczak E, Konradsen F, et al. Multiple-dose activated charcoal in acute self-poisoning: a randomised controlled trial. Lancet. 2008;371(9612):579-587. PMID: 18242844.
48. Bond GR, Requa RK, Krenzelok EP, et al. Influence of time until emesis on the efficacy of decontamination using acetaminophen as a marker. Ann Emerg Med. 1992;21(7):762-767. PMID: 1588855.
49. Krenzelok EP, McGuigan M, Lheur P. Position statement: ipecac syrup. J Toxicol Clin Toxicol. 1997;35(7):699-709. PMID: 9385491.
50. Goldfrank LR, Flomenbaum NE, Lewin NA, et al. Goldfrank's Toxicologic Emergencies. 10th ed. New York: McGraw-Hill; 2015. PMID: 25693012.
51. Hoffman RS. The poisoned patient with altered consciousness. JAMA. 1995;274(21):1682-1687. PMID: 7500727.
52. Hoffman RS, Nelson LS. The changing face of acetaminophen poisoning. Am J Ther. 1999;6(3):173-174. PMID: 10209957.
53. Bailey B, McGuigan MA. Management of toxic alcohol ingestion. Emerg Med Clin North Am. 2007;25(2):385-396. PMID: 17485141.
54. Waring WS. Management of lithium toxicity. Drugs. 2007;67(13):1941-1951. PMID: 17877507.
55. Isbister GK, Buckley NA. The pathophysiology of serotonin toxicity in animals and humans: implications for diagnosis and treatment. Clin Neuropharmacol. 2005;28(5):205-214. PMID: 16189461.