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Toxicology / Poisoning

General Management of Poisoning

General approach to managing the bodily entry of toxic substances that cause dysfunction. Covers supportive care, decontamination, antidotes, and enhanced elimination, emphasizing stabilization and symptomatic treatment as specific identification/antidotes are often unavailable.

Also known as: Poisoning Approach, Toxicology Management Principles

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Referral and warning signs

When to refer

Refer ALL patients with significant signs of poisoning to hospital (HC4/H) if possible. Refer patients who ingested potentially dangerous substances known for delayed toxicity (e.g., paracetamol, salicylates, iron, TCAs, paraquat, modified-release drugs) even if initially asymptomatic. Refer if requiring advanced supportive care (e.g., ventilation, vasopressors), specific antidotes not available locally, enhanced elimination techniques (MDAC, alkalinization, haemodialysis), or psychiatric evaluation (if intentional).

Red flags

  • Altered mental status (drowsiness, confusion, coma)
  • Respiratory depression or distress (slow/shallow breathing, hypoxia)
  • Hypotension or signs of shock
  • Seizures
  • Significant cardiac arrhythmias or ECG abnormalities (e.g., wide QRS, prolonged QTc)
  • Severe acid-base disturbance
  • Hyperthermia or hypothermia
  • Ingestion of a substance known to be highly toxic or have delayed effects

Signs and symptoms

  • Variable depending on poison
  • Altered level of consciousness (confusion, drowsiness, coma)
  • Respiratory distress or depression
  • Cardiovascular instability (hypotension, hypertension, arrhythmias)
  • Temperature changes (hypothermia, hyperthermia)
  • Seizures
  • Nausea, vomiting, abdominal pain
  • Skin changes (burns, flushing, cyanosis, sweating)
  • Abnormal pupil size or reactivity

Risk factors

  • Ingestion (most common)
  • Inhalation (gases, fumes, smoke)
  • Injection (drugs of abuse, bites/stings)
  • Cutaneous/mucosal absorption (pesticides, chemicals)
  • Intentional exposure (suicide attempt, homicide)
  • Unintentional exposure (medication error, accidental ingestion by children, occupational/environmental hazard)

Diagnosis

Clinical assessment

Based on history of exposure (if known, including substance, amount, time), clinical presentation (toxidrome recognition), and vital signs assessment. Identifying the specific poison is ideal but often challenging; management frequently relies on symptom patterns.

Investigations

  • Vital signs monitoring (BP, HR, RR, SpO2, Temperature)
  • Point-of-care Blood Glucose
  • Electrocardiogram (ECG) - essential for many poisonings affecting heart rhythm/conduction
  • Specific toxin levels (e.g., paracetamol, salicylate, digoxin, alcohol, COHb) if available and clinically indicated
  • Basic laboratory tests based on clinical picture: Electrolytes (including anion gap), Renal function tests (Urea, Creatinine), Liver function tests (LFTs), Arterial Blood Gas (ABG) for acid-base status and oxygenation, Complete Blood Count (CBC), Urinalysis
  • Imaging (Chest X-ray for aspiration/pulmonary edema, Abdominal X-ray for radio-opaque substances, CT head if altered mental status unexplained or trauma)

Diagnostic criteria

Diagnosis often presumptive based on history and clinical syndrome (toxidrome), supported by investigations. Specific criteria apply to individual poisons.

Management

Non-pharmacological management

  • Ensure safety of patient and rescuers.
  • Minimize/Stop Exposure: Remove patient from source. Remove contaminated clothing (use PPE). Wash contaminated skin thoroughly with soap and water.
  • Stabilization (ABCDE Approach): Airway: Clear and maintain patent airway (positioning, suction, adjuncts, intubation if needed). Breathing: Assess adequacy, provide oxygen, assist ventilation (bag-mask, mechanical ventilation). Circulation: Establish IV access (large bore). Manage hypotension/hypertension, treat arrhythmias (ACLS protocols). Disability: Assess GCS, pupils, check blood glucose. Exposure: Fully expose patient to check for injuries/skin contamination, prevent/treat hypothermia.
  • Decontamination (AFTER Stabilization): Evaluate risk/benefit.
  • - Skin/Eye Decontamination: Copious irrigation with water/saline.
  • - Gastric Decontamination: Avoid inducing vomiting (emesis). Gastric Lavage: Limited utility (consider only if <1-2 hours post-ingestion of life-threatening amount of certain poisons, e.g., salicylates, anticholinergics up to 4-6h; contraindicated if airway unprotected, caustic/hydrocarbon ingestion).
  • Temperature Control: Passive/active rewarming for hypothermia. Tepid sponging/cooling blankets for hyperthermia.

Pharmacological treatment

  • Supportive Medications:
  • - IV Fluids: Normal Saline or Ringer's Lactate for hypotension, dehydration, maintaining venous access.
  • - Anticonvulsants: Diazepam (Adult: 10mg rectal or 5-10mg slow IV, repeat PRN up to 30mg; Child: 0.5mg/kg rectal or 0.2mg/kg slow IV, repeat PRN max 10mg) or Lorazepam.
  • - Vasopressors (e.g., Norepinephrine): For refractory hypotension (Hospital level).
  • Prevention of Absorption:
  • - Activated Charcoal (Oral/NGT): Give ASAP if indicated (within 1-2 hours, potentially longer for modified-release/anticholinergic poisons). Binds many poisons, reducing absorption. Dose: Adult 50g; Child 0.5-1g/kg. Mix powder with 100-200ml water. Contraindications: Unprotected airway, late presentation, caustic/hydrocarbon ingestion, poisons poorly adsorbed (metals, alcohols, lithium, iron, cyanide), intestinal obstruction/ileus.
  • Enhanced Elimination:
  • - Multiple-Dose Activated Charcoal (MDAC): 25-50g q2-4h. Enhances elimination of certain drugs undergoing enterohepatic recirculation (e.g., phenobarbital, theophylline, carbamazepine, quinine, salicylates). Requires protected airway and bowel sounds.
  • - Urinary Alkalinization: IV Sodium Bicarbonate infusion to achieve urine pH 7.5-8.5. Enhances renal excretion of weak acids (e.g., salicylates, phenobarbital). Requires careful monitoring (Hospital level).
  • - Haemodialysis/Haemoperfusion: Effective for removing certain toxins (e.g., salicylates, methanol, ethylene glycol, lithium, phenobarbital). Indications depend on toxin, severity, clinical status (Hospital/RR).
  • Specific Antidotes: Use if available and indicated for specific poison (refer to individual entries, e.g., Naloxone for opioids, Acetylcysteine for paracetamol, Atropine/Pralidoxime for organophosphates, Vitamin K for warfarin).

Monitoring

Continuous monitoring of vital signs (HR, BP, RR, SpO2, Temp). Continuous ECG monitoring if cardiotoxic substance suspected. Frequent neurological assessment (GCS, pupils). Monitor fluid balance, urine output. Monitor blood glucose frequently. Repeat relevant labs (ABG, electrolytes, toxin levels) as indicated.

Complications

  • Variable depending on poison: Respiratory failure, Aspiration pneumonia, Cardiovascular collapse/shock, Arrhythmias, Acute kidney injury, Acute liver failure, Rhabdomyolysis, Cerebral edema, Seizures, Coma, Long-term neurological sequelae, Death

Prevention

  • Safe storage of medications, chemicals, pesticides away from children.
  • Proper labeling of all containers.
  • Use of child-resistant packaging.
  • Safe use practices for occupational/household chemicals (PPE, ventilation).
  • Patient education on correct medication use and dosage.
  • Awareness of potential hazards in the environment.
  • Mental health support to address intentional self-poisoning.

Patient education

  • Counsel patient and families concerning poisoning prevention strategies.
  • Explain the treatment approach and rationale.
  • Address underlying issues if poisoning was intentional, emphasizing need for psychiatric follow-up and support.

Uganda-specific notes

Knowledge of the specific poison helps anticipate effects, but management is primarily symptomatic and supportive due to limited diagnostic/antidote availability. Gastric lavage usefulness is limited and carries risks. Activated charcoal is widely applicable but has specific contraindications. Note mandatory referral criteria for certain poisons even if asymptomatic. Follow UCG guidelines closely. Ensure patient/rescuer safety during decontamination.

References

  • Uganda Clinical Guidelines (UCG) 2023

    Chapter 1, Section 1.3.1, 1.3.1.2

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