FM13.{6,8} | Diagnosis & General Management of Poisoning — Summary & Reflection

KEY TAKEAWAYS

General management of poisoning follows four sequential pillars: decontamination → supportive care → antidotes → enhanced elimination, always preceded by rapid clinical diagnosis using history, toxidromes, and investigations.

Decontamination: external (copious water irrigation — no neutralisation); GI (gastric lavage within 1-2 hours — contraindicated for corrosives and petroleum distillates; activated charcoal 1 g/kg — ineffective for iron, lead, lithium, alcohols, acids, alkalis; WBI for iron, sustained-release tablets, body packers). Supportive care: ABC framework — airway/intubation for GCS ≤8; high-flow O₂ (100% O₂ and hyperbaric for CO); IV access, crystalloid resuscitation; benzodiazepines first-line for seizures (not phenytoin for TCA/cocaine); correct hypoglycaemia promptly.

Antidotes: naloxone (opioids — receptor antagonist; half-life shorter than most opioids — monitor for re-narcotisation); atropine (OP — end-point = dry secretions, not tachycardia) + pralidoxime/PAM (OP — within 24-48h before ageing; does NOT replace atropine); NAC (paracetamol — within 8h best; Rumack-Matthew nomogram guides initiation); flumazenil (benzodiazepines — contraindicated in chronic users/TCA co-ingestion); desferrioxamine (iron); digoxin-FAB (cardiac glycosides); ethanol or fomepizole (methanol/ethylene glycol).

Enhanced elimination: forced alkaline diuresis (salicylates, phenobarbital — ion trapping); haemodialysis (salicylates, methanol, ethylene glycol, lithium — low Vd, water-soluble); haemoperfusion (paraquat, theophylline, carbamazepine); MDAC (theophylline, carbamazepine, phenobarbital — gut dialysis). Medicolegal obligations: police intimation (mandatory, statutory), contemporaneous documentation, chain of custody for samples.

REFLECT

Return to the paracetamol overdose case from the opening. She presented 2 hours post-ingestion and seemed well. Now apply the framework: at what time exactly would you measure her serum paracetamol level (4 hours post-ingestion), how would you apply the Rumack-Matthew nomogram, and what is the cost — in terms of outcome — of waiting for symptoms before starting NAC? Consider also the medicolegal dimension: if this patient were a minor brought in by parents who initially refused hospital admission, what are your legal obligations? Finally, reflect on systems thinking: India has significant NAC supply gaps in district hospitals. What systematic change — regulatory, procurement, or training — would most reduce paracetamol-related hepatic failure mortality in your region?