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Poisoning

Specialties > Child health

Differential Diagnosis Schema 🧠

Common Poisons and Toxins

  • Paracetamol (Acetaminophen) toxicity: Nausea, vomiting, right upper quadrant pain, risk of hepatotoxicity, especially after 24 hours.
  • Opioid overdose: Respiratory depression, miosis, altered mental status, reduced bowel sounds.
  • Salicylate poisoning (e.g., aspirin): Hyperventilation, tinnitus, metabolic acidosis with respiratory alkalosis, confusion.
  • Benzodiazepine overdose: CNS depression, drowsiness, ataxia, slurred speech, respiratory depression in severe cases.
  • Alcohol poisoning: CNS depression, hypoglycemia, metabolic acidosis, hypothermia.
  • Carbon monoxide poisoning: Headache, dizziness, cherry-red skin, altered mental status, metabolic acidosis.
  • Tricyclic antidepressants (TCA) overdose: Anticholinergic effects, wide QRS on ECG, seizures, hypotension.
  • Iron poisoning: Abdominal pain, vomiting, metabolic acidosis, organ failure, particularly liver.
  • Organophosphate poisoning: Salivation, lacrimation, urination, defecation, GI upset, miosis, muscle twitching.
  • Methanol or ethylene glycol poisoning: Metabolic acidosis, visual disturbances (methanol), renal failure (ethylene glycol), CNS depression.
  • Cyanide poisoning: Rapid onset of confusion, seizures, cardiac arrest, bitter almond smell.
  • Lithium toxicity: Tremor, hyperreflexia, nystagmus, altered mental status, nephrogenic diabetes insipidus.
  • Beta-blocker overdose: Bradycardia, hypotension, hypoglycemia, bronchospasm.
  • Calcium channel blocker overdose: Hypotension, bradycardia, hyperglycemia, cardiac conduction delays.
  • Digoxin toxicity: Nausea, vomiting, xanthopsia (yellow vision), arrhythmias (e.g., AV block, ventricular arrhythmias).
  • Theophylline toxicity: Tachycardia, tremor, seizures, vomiting, hypokalemia.
  • Cocaine toxicity: Hypertension, tachycardia, hyperthermia, seizures, myocardial infarction.
  • Amphetamine overdose: Agitation, hyperthermia, hypertension, tachycardia, seizures.
  • Lead poisoning: Abdominal pain, anemia, peripheral neuropathy, cognitive dysfunction, basophilic stippling of RBCs.
  • Mercury poisoning: Tremor, neuropsychiatric symptoms, gingivitis, renal impairment.

Key Points in History 🥼

Exposure History

  • Substance involved: Identify the specific agent or toxin, including brand names and formulations.
  • Dose and quantity: Estimate the amount ingested or exposed to, and the time of exposure.
  • Route of exposure: Consider ingestion, inhalation, dermal contact, or injection.
  • Timing: Time since exposure is critical in determining management and prognosis.
  • Intent: Accidental vs. intentional (e.g., self-harm, overdose) influences management and psychiatric evaluation.
  • Co-ingestants: Consider other substances taken in conjunction with the primary toxin.
  • Alcohol or drug use: Alcohol and recreational drugs can potentiate or modify the effects of the toxin.
  • Chronic exposure: Relevant in cases of heavy metals, certain drugs, or occupational hazards.
  • Workplace hazards: Consider occupational exposure to industrial chemicals, heavy metals, or other toxins.
  • Recent travel: Travel to areas with endemic toxins, infectious diseases, or environmental hazards.
  • Previous similar episodes: Helps in recognizing chronic or repeated exposure.
  • Access to medications or chemicals: Consider accessibility in cases of pediatric or vulnerable adult poisoning.
  • Psychiatric history: Important in cases of intentional overdose or poisoning.

Symptoms and Clinical Course

  • Onset of symptoms: Timing of symptom onset post-exposure can provide clues to the type of toxin.
  • Nature of symptoms: Neurological (e.g., seizures, altered consciousness), cardiovascular (e.g., bradycardia, hypotension), gastrointestinal (e.g., vomiting, diarrhea), or respiratory (e.g., dyspnea, hypoxia).
  • Progression: Whether symptoms are worsening, stabilizing, or improving provides insight into the severity and potential outcomes.
  • Associated factors: Consider environmental factors, co-ingestants, or concurrent medical conditions that may influence the clinical picture.
  • Previous treatments: Any initial treatment provided (e.g., activated charcoal, antidotes) before presentation.
  • Chronicity: Recurrent or chronic exposure may present differently from acute poisoning.
  • Exacerbating factors: Physical exertion, stress, or specific activities that may aggravate symptoms.
  • Improvement factors: Any measures or medications that have provided symptom relief.

Possible Investigations 🌡️

Laboratory Tests

  • Blood glucose: Hypoglycemia is common in alcohol and salicylate poisoning, as well as in insulin or oral hypoglycemic overdose.
  • Arterial blood gases (ABG): To assess acid-base status, particularly in salicylate, methanol, and ethylene glycol poisoning.
  • Electrolytes and renal function (U&E): To assess for anion gap metabolic acidosis, renal impairment, and electrolyte disturbances.
  • Liver function tests (LFTs): To assess hepatotoxicity, particularly in paracetamol poisoning.
  • Coagulation profile: Important in assessing coagulopathy in cases like warfarin or rodenticide poisoning.
  • Toxicology screen: To detect specific drugs or toxins in blood or urine.
  • Serum drug levels: For specific toxins like paracetamol, salicylates, lithium, digoxin, and theophylline.
  • Carboxyhemoglobin levels: Essential in suspected carbon monoxide poisoning.
  • Osmolality and osmolar gap: Useful in cases of methanol or ethylene glycol poisoning.
  • Creatine kinase (CK): Elevated in severe cases of rhabdomyolysis, which can occur in stimulant or seizure-related poisoning.
  • Electrocardiogram (ECG): To assess for cardiac arrhythmias, especially in TCA, digoxin, or beta-blocker toxicity.
  • Lactate levels: Elevated in severe sepsis, carbon monoxide poisoning, or cyanide poisoning.
  • Ammonia levels: Elevated in severe liver failure, which may complicate poisoning cases such as paracetamol overdose.
  • Pregnancy test: Important in females of childbearing age to assess for potential fetal risks.

Imaging and Other Tests

  • Chest X-ray: Useful in cases of aspiration, pulmonary edema, or hydrocarbon inhalation.
  • CT scan of the head: Consider in cases of altered mental status, seizures, or head injury secondary to poisoning.
  • Abdominal X-ray: Can identify ingested radiopaque substances, such as heavy metals or drug packets.
  • EEG: Consider if seizures are present or if encephalopathy is suspected.
  • Endoscopy: May be indicated in caustic ingestion to assess the extent of gastrointestinal injury.
  • Urinalysis: To detect the presence of toxins, hematuria, or myoglobinuria in cases of rhabdomyolysis.
  • Holter monitoring: May be necessary to detect intermittent arrhythmias in cardiotoxic poisoning.
  • Pulse oximetry and capnography: Continuous monitoring in cases of respiratory compromise or sedation.
  • Gastric lavage: Consider in very early presentations if a life-threatening amount of toxin has been ingested.
  • Activated charcoal administration: Can be considered within the first hour of ingestion if the toxin is adsorbed by charcoal.
  • Serial serum levels: Necessary for monitoring toxins with a risk of delayed toxicity, such as paracetamol or iron.
  • Psychiatric evaluation: Crucial in cases of intentional overdose or in patients with a history of self-harm.
  • Consultation with toxicology: Consider in complex cases or if the poison is unfamiliar.
  • Multidisciplinary care: May involve collaboration with nephrology (for dialysis), cardiology, or intensive care.

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