Poisoning and Toxidromes

General Management - First Aid & Fixes

• ABCDE Assessment: Prioritize airway, breathing, circulation, disability, exposure.
• Decontamination:
  • Gastric Lavage: If <1 hour & life-threatening. C/I: corrosives, hydrocarbons, no airway protection.
  • Activated Charcoal: 1 g/kg. Adsorbs many toxins. Not for: 📌 PHAILS (Pesticides, Hydrocarbons, Acids/Alkalis/Alcohols, Iron, Lithium, Solvents), corrosives.
  • Whole Bowel Irrigation (PEG): For SR drugs, body packers, Fe, Li.
• Enhanced Elimination:
  • Alkaline Diuresis: Salicylates, phenobarbital. Target urine pH 7.5-8.5.
  • Hemodialysis: Severe poisoning. 📌 I STUMBLE (Isopropyl alcohol, Salicylates, Theophylline, Uremia, Methanol, Barbiturates (long), Lithium, Ethylene glycol).
• Antidotes: Specific agents. E.g., Naloxone (opioid antagonist), N-acetylcysteine (paracetamol - replenishes glutathione).

⭐ Activated charcoal is most effective if given within 1 hour of poison ingestion.

Toxidrome Detective - Spot The Signs

Common Culprits 1 - Deadly Doses

• Paracetamol (Acetaminophen)
  • Toxic dose: Child >150 mg/kg; Adult >7.5-10 g.
  • Stages:
    • Stage 1 (<24h): N/V.
    • Stage 2 (24-72h): RUQ pain, ↑LFTs.
    • Stage 3 (72-96h): Hepatic failure, encephalopathy.

      ⭐ Peak LFT derangement occurs at 72-96h (Stage 3).

    • Stage 4 (>4d): Recovery/death.
  • Management: Rumack-Matthew nomogram guides N-acetylcysteine (NAC).

• Organophosphates (OPs)
  • Mechanism: Irreversible $AChE$ inhibition $\rightarrow ACh \uparrow$.
  • Features:
    • Muscarinic (DUMBELS 📌): Diarrhea, Urination, Miosis, Bronchorrhea/spasm, Emesis, Lacrimation, Salivation.
    • Nicotinic: Weakness, fasciculations, paralysis.
    • CNS: Seizures, coma.
  • Management:
    • Atropine: (e.g., 0.02-0.05 mg/kg child; 1-2 mg adult, titrate).
    • Pralidoxime (PAM): (e.g., 25-50 mg/kg child; 1-2 g adult).

Common Culprits 2 - Tricky Toxins

• Salicylates (Aspirin)

  • Mechanism: Uncouples oxidative phosphorylation.
  • Features: Tinnitus, hyperventilation, fever; respiratory alkalosis → ↑ anion gap metabolic acidosis.
  • Done Nomogram: Assesses severity (>6 hrs post-ingestion).
  • Rx: ABCs, charcoal (early), IV fluids, NaHCO₃ (urine pH 7.5-8), glucose, K⁺, hemodialysis (severe, levels >100 mg/dL).

• Iron

  • Toxic: Elemental Fe >20 mg/kg (mild), >60 mg/kg (severe).
  • Stages (5): GI → Latent → Shock/Acidosis → Hepatic Failure → Scarring.
  • Rx: Supportive, WBI. Desferrioxamine (IV) if Fe >500 µg/dL or severe.

  ⭐ Desferrioxamine causes "vin rosé" urine (iron chelation).

• Kerosene/Hydrocarbons

  • Risk: Aspiration pneumonitis.
  • CNS: Lethargy, ataxia, seizures.
  • Rx: Supportive, O₂. ⚠️ NO gastric lavage/emesis. Antibiotics if infection. 📌 Kerosene: Keep emesis out!

High‑Yield Points - ⚡ Biggest Takeaways

• Organophosphate poisoning: cholinergic crisis (DUMBELS); treat with atropine, pralidoxime.
• Paracetamol toxicity: hepatic necrosis; antidote N-acetylcysteine (NAC), use Rumack-Matthew nomogram.
• Iron poisoning: GI, CV, hepatic toxicity; chelator deferoxamine.
• Salicylate toxicity: respiratory alkalosis then metabolic acidosis; manage: alkaline diuresis, hemodialysis.
• Opioid overdose triad: CNS depression, respiratory depression, miosis; antidote naloxone.
• Anticholinergic toxidrome: "mad, blind, red, hot, dry"; physostigmine for severe symptoms (cautious use).