Resuscitation (toxicology)

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Related FACEM curriculum (2022) learning objectives:

• Learning OutcomesPrinciples of assessment of toxicological presentations in the ED, including: Triage and initial assessment
• ME 3.8.3.5(a) Lead a team to resuscitate a patient with: Toxicological presentation

Resuscitation

• Significance:
  • Poisoning is a leading cause of death in patients <40 years old.
  • Common differential diagnosis in young adults with cardiac arrest.
• Resuscitation in Poisoning:
  • Prolonged cardiopulmonary resuscitation (CPR) may result in good neurological outcomes.
  • Continue resuscitation during cardiac arrest until expert advice is obtained.
  • Extracorporeal membrane oxygenation (ECMO): Life-saving therapy for refractory shock or respiratory distress.
• Decontamination:
  • Skin or gastrointestinal decontamination is secondary to resuscitation and supportive care.

Airway, Breathing, and Circulation (ABC) in Poisoning

• Acute poisoning can rapidly worsen.
• Key threats: Altered consciousness, loss of airway reflexes, hypotension.
• Follow standard emergency protocols unless specific toxicological interventions are indicated.
• Clinical scores (e.g., GCS) may not reliably assess airway protection.

Specific Issues

Seizures

• Characteristics:
  • Usually generalized in toxicological causes.
  • Common agents: Venlafaxine, tramadol, amphetamines, bupropion.
  • Ethanol/benzodiazepine withdrawal also implicated.
• Management:
  • First-line: IV benzodiazepines (diazepam, midazolam, clonazepam).
  • Refractory seizures: Barbiturates or pyridoxine (if isoniazid-related).
  • Contraindicated: Phenytoin (exacerbates sodium channel blockade).

Hypoglycaemia

• Detection:
  • Check bedside blood glucose (BGL) in all patients with altered mental status.
  • Hypoglycaemia: BGL <4.0 mmol/L.
• Management:
  • Adults: IV 50 mL of 50% dextrose.
  • Children: 5 mL/kg of 10% dextrose

Hyper-/Hypothermia

• Hyperthermia:
  • Emergency if >39.5°C; requires neuromuscular paralysis, intubation, ventilation.
  • Continuous core temperature monitoring >38.5°C.
• Hypothermia (<29°C):
  • Mimics cardiac arrest (e.g., coma, bradycardia).
  • Requires aggressive rewarming, CPR, and possibly ECMO or pleural lavage.

Toxicology-Specific Resuscitation Challenges

Airway

• Corrosive Injury:
  • Agents: Alkalis, acids, glyphosate, paraquat.
  • Stridor, dysphagia, and dysphonia = imminent airway compromise.
  • Early intubation or surgical airway often required.

Breathing

• Acidosis:
  • Agents: Ethylene glycol, methanol, salicylates.
  • Maintain hyperventilation; avoid hypoventilation.
  • Consider IV sodium bicarbonate.
• Hypoventilation:
  • Cause: Opioids.
  • Naloxone may prevent intubation.
• Respiratory Failure:
  - Agents: Carbamates, organophosphates (cholinergic crisis).
  • Atropine titration until secretions dry to restore oxygenation.
• Hypoxemia:
  Agent: Paraquat.
  • Limit oxygen to maintain SpO₂ ~90% or PaO₂ ~60 mmHg.

Circulation

• Ventricular Arrhythmias:
  - Fast sodium channel blockade (e.g., tricyclic antidepressants, chloroquine).
  • Treatment: IV sodium bicarbonate, avoid amiodarone/procainamide.
• Tachycardia:
  - Agents: Amphetamines, cocaine (sympathomimetic response).
  • Treatment: IV benzodiazepines, avoid beta-blockers.
• Cardiac Arrest:
  - Agent-specific interventions: Lipid emulsion for local anaesthetics; digoxin-specific antibodies for digoxin toxicity.

Antidotes

• Key Antidotes in Resuscitation:
  • Sodium bicarbonate: Tricyclic antidepressants.
  • Naloxone: Opioid toxicity.
  • Atropine: Organophosphorus agents.
  • Digoxin-specific antibodies: Digoxin poisoning with cardiovascular compromise.
• Weigh benefits against adverse effects and contraindications.