Toxicological Emergencies

Poisoning Principles - Detox Blueprint

1. Initial Management:

• Stabilize: ABCs (Airway, Breathing, Circulation), Vitals, GCS.
• History: 📌 AMPLE (Allergies, Medications, Past history, Last meal, Events).
• Examination: Identify toxidromes.

2. Decontamination (Reduce Absorption):

• Activated Charcoal: 1g/kg PO/NG. Contra: corrosives, hydrocarbons, poor GI motility, no bowel sounds.
• Gastric Lavage: Within 1 hr for life-threatening ingestions if airway protected. Contra: corrosives, hydrocarbons.
• Whole Bowel Irrigation (WBI): Polyethylene glycol for body packers, sustained-release/enteric-coated drugs.

3. Enhanced Elimination (Increase Excretion):

• Forced Diuresis: Alkaline (e.g., salicylates, phenobarbital) using $NaHCO_3$ for ion trapping ($pH = pKa + log([A^-]/[HA])$).
• Hemodialysis: For low MW, low Vd, water-soluble toxins (methanol, ethylene glycol, salicylates, lithium).
• Hemoperfusion: For drugs binding charcoal (theophylline, carbamazepine, phenobarbital).

⭐ Activated charcoal is not effective for heavy metals (Pb, Hg, As), iron, lithium, alcohols, and corrosives.

Toxidrome Titans - Syndrome Sleuth

Recognize patterns for diagnosis. Key differentiating features:

• 📌 Anticholinergic: "Mad as a hatter (delirium), Blind as a bat (mydriasis), Red as a beet (flushed), Hot as a hare (hyperthermia), Dry as a bone (dry)."

⭐ Miosis is a key feature differentiating opioid toxidrome from sedative-hypnotic toxidrome (which usually has variable pupils, often normal).

Common Culprits - Poison Parade

• Organophosphates (OPC)

  • Mech: Irreversible AChE inhibitor → ↑ACh.
  • Features: 📌 DUMBELS/SLUDGE-M (Cholinergic crisis); muscle fasciculations, paralysis.
  • Antidote: Atropine (2-5 mg IV q 5-15 min); Pralidoxime (PAM) (1-2 g IV).
  • Mgmt: Decontamination, airway support.

• Paracetamol (Acetaminophen)

  • Mech: Toxic metabolite NAPQI depletes glutathione → liver damage.
  • Features: N/V (early); ↑LFTs, jaundice, encephalopathy (late).
  • Antidote: N-acetylcysteine (NAC) IV loading dose 150 mg/kg.
  • Mgmt: Activated charcoal (<4h). Rumack-Matthew nomogram ($[Paracetamol]_{serum}$ vs. time).

  ⭐ In paracetamol poisoning, N-acetylcysteine is most effective if given within 8 hours of ingestion.

• Opioids

  • Mech: Mu-receptor agonist.
  • Features: Triad: miosis, respiratory depression, ↓LOC.
  • Antidote: Naloxone (0.4-2 mg IV/IM/SC).
  • Mgmt: Airway, ventilation.

• Salicylates (Aspirin)

  • Mech: Uncouples oxidative phosphorylation, resp. center stimulation.
  • Features: Tinnitus, hyperthermia, tachypnea; resp. alkalosis → metabolic acidosis. 📌 MUDPILES.
  • Antidote: Sodium bicarbonate (urinary alkalinization, target urine pH 7.5-8.0).
  • Mgmt: IV fluids, glucose. Hemodialysis if severe (e.g., level >80-100 mg/dL acute).

Antidote Arsenal - Remedy Roster

High‑Yield Points - ⚡ Biggest Takeaways

• Organophosphate poisoning: Atropine for muscarinic effects, Pralidoxime reactivates cholinesterase.
• Paracetamol poisoning: N-acetylcysteine is the specific antidote, best within 8-10 hours.
• Opioid overdose: Naloxone reverses respiratory depression, miosis, and coma.
• Cyanide poisoning: Treat with hydroxocobalamin or sodium nitrite + sodium thiosulfate.
• Methanol/Ethylene glycol: Fomepizole or ethanol for HAGMA; consider hemodialysis.
• Salicylate toxicity: Mixed acid-base disturbance; manage with alkaline diuresis, hemodialysis.