🧪 Poisons Eliminated by Haemodialysis & Haemofiltration: Some poisons and drug overdoses can be life-threatening 🚨. Extracorporeal removal methods - haemodialysis and haemofiltration - can clear these toxins effectively. Best suited when toxins are 💧 water-soluble, ⚖️ low molecular weight, 🩸 low protein bound, and have a 📦 small volume of distribution.

🔄 Extracorporeal Methods in Poisoning

Extracorporeal toxin removal is considered when a poison is life-threatening, poorly managed by supportive care alone, and has favourable pharmacokinetics (low MW, low protein binding, small Vd, water soluble).

Haemodialysis 💉: Removes toxins by diffusion across a semipermeable membrane. Best for:
- Low molecular weight
- Low protein binding
- Small volume of distribution
Haemofiltration 🩸: Removes toxins by convection (solvent drag with plasma water). Useful for:
- Moderately protein bound drugs
- Larger volume of distribution
- When patient is haemodynamically unstable (continuous therapy)

💉 Haemodialysis – Classic Toxins
Methanol 🧴: → formic acid → visual toxicity, acidosis. Dialysis clears parent + metabolites. Ethylene Glycol 🧊: → severe acidosis, renal failure. Dialysis removes glycol + oxalate metabolites. Salicylates 💊: → mixed acidosis/alkalosis, tinnitus, CNS signs. Dialysis corrects acid–base + drug clearance. Lithium 🔋: → tremor, confusion, seizures, renal impairment. Dialysis = treatment of choice. Sodium Valproate 💊: → CNS depression, hyperammonaemia. Dialysis rapidly lowers levels in overdose. Isopropanol 🧽: → CNS depression, ketosis (no acidosis). Dialysis clears isopropanol + acetone.
🩸 Haemofiltration – Useful Agents
Theophylline 🌬️: → arrhythmias, seizures. Filtration aids in prolonged toxicity. Phenytoin 💊: → ataxia, CNS depression. Moderately protein-bound but cleared if severe overdose. Carbamazepine ⚡: → coma, seizures. Haemofiltration helps in prolonged toxicity. Phenobarbital 😴: → CNS + respiratory depression. Filtration effective despite protein binding.

📌 Key Clinical Points

Both haemodialysis and haemofiltration can be life-saving in severe poisoning.
Choice depends on toxin PK + patient stability (HD faster, HF better in unstable patients).
Always combine with supportive care: airway, fluids, electrolytes, acid–base correction.
Early consultation with toxicology/NPIS (TOXBASE in UK) and critical care is essential.

💡 Exam Pearl: Use the mnemonic "MELSIL" for haemodialysis toxins: Methanol, Ethylene glycol, Lithium, Salicylates, Isopropanol, Levels of valproate.

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Poisons eliminated Haemodialysis - perfusion

🔄 Extracorporeal Methods in Poisoning

📌 Key Clinical Points

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