ICU · Toxicology
Acute severe poisonings: decontamination, antidotes, and enhanced elimination
Also known as Toxicology general approach · Decontamination · Activated charcoal · Whole bowel irrigation · Haemodialysis for toxins · Antidotes
A systematic approach to the poisoned patient: RESUSCITATE (ABC, oxygenation, ventilation, circulation — toxins cause coma, seizures, arrhythmia, hypotension), then DECONTAMINATION (reduce absorption — activated charcoal within 1h, whole bowel irrigation for sustained-release/iron/packets, gastric lavage rarely for life-threatening ingestions <1h), ENHANCED ELIMINATION (multi-dose activated charcoal, urinary alkalinisation for salicylates, haemodialysis for toxic alcohols/salicylates/lithium/metformin), ANTIDOTES (specific — naloxone opioids, NAC paracetamol, flumazenil benzos [caution], atropine/pralidoxime organophosphates, digoxin Fab, fomepizole toxic alcohols, hydroxocobalamin cyanide, octreotide sulfonylureas, glucagon beta-blockers/CCB, lipid emulsion lipophilic drugs). ALWAYS: check paracetamol + salicylate levels, ECG, glucose, temperature; call poison centre; observe for delayed toxicity (sustained-release).
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CICMFFICMEDIC
Red flags
- ABC first — poisoned patients die from airway loss, hypoxia, aspiration
- Activated charcoal within 1h (or sustained-release) — NOT if altered consciousness without airway protection
- Paracetamol + salicylate levels in EVERY unknown ingestion
- ECG in all poisonings — Na channel blockers (TCAs), K channel blockers cause arrhythmia
- Haemodialysis for: toxic alcohols, salicylates, lithium, metformin, valproate
[1]
Decontamination methods compared
[2]
[1]
[8]
[9]
[10]
[20]
| Method | Indication | Timing | Contraindications | Effectiveness |
|---|---|---|---|---|
| Activated charcoal | Most oral ingestions (within 1h) | Most effective within 1h; 2026 consensus judges many poisons still appropriate up to 6h; sustained-release any time | Altered consciousness (without airway protection), acids/alkalis, hydrocarbons, iron, lithium, metals | Mean absorption reduction 47% at 30 min, 40% at 1h (volunteer data) |
| Whole bowel irrigation (polyethylene glycol) | Sustained-release drugs, iron, lithium, body-packers | As soon as possible | Bowel obstruction, ileus, haemodynamic instability, unprotected airway | Flushes drug through GI (1-2 L/hr NG until clear effluent) |
| Gastric lavage | Life-threatening ingestion <1h, not adsorbed by charcoal (iron, lithium) | <1h (rarely used) | Altered consciousness (aspiration risk), caustics, late presentation | Controversial — limited benefit, aspiration risk |
| Haemodialysis | Toxic alcohols, salicylates, lithium, metformin, valproate | Any time (if indicated by level/severity) | Haemodynamic instability (relative — use CRRT), no vascular access | Removes drug from blood directly; intermittent HD most efficient |
| Urinary alkalinisation | Salicylates (moderate-severe), phenobarbital | Any time | Pulmonary oedema (sodium load), alkalosis | Traps ionised drug in alkali urine |
Toxidromes — pattern recognition at the bedside
[3]| Toxidrome | Classic agents | Mental state | Pupils | Vitals | Secretions / skin | Hallmark |
|---|---|---|---|---|---|---|
| Sympathomimetic | Cocaine, amphetamines, MDMA, pseudoephedrine, theophylline | Agitated, hyperalert, paranoid | Mydriasis | Tachycardia, hypertension, hyperthermia, tachypnoea | Diaphoresis (sweating), piloerection, tremor | "Wired, wet, wide-eyed" |
| Anticholinergic | Atropine, TCAs, antihistamines, benztropine, hyoscine | Delirium, mumbling, hallucinations | Mydriasis | Tachycardia, mild hyperthermia | Dry, flushed, hot skin; urinary retention, ileus | "Mad as a hatter, blind as a bat, hot as a hare, dry as a bone, red as a beet, full as a flask" |
| Cholinergic (muscarinic) | Organophosphates, carbamates, nerve agents (sarin) | Confusion → coma | Miosis | Bradycardia, hypotension (may be tachy via nicotinic) | Profuse salivation, lacrimation, urination, defecation, bronchorrhoea | DUMBELS / SLUDGE, bronchospasm |
| Cholinergic (nicotinic) | Same agents — nicotinic effects | As above | Variable | Tachycardia, hypertension (ganglionic stimulation) | Fasciculations, weakness → flaccid paralysis | MTWtHF: Mydriasis, Tachycardia, Weakness, Hypertension, Fasciculations |
| Opioid | Morphine, heroin, fentanyl, methadone, oxycodone | Coma, euphoria | Miosis ("pinpoint") | Bradypnoea/hypoventilation, bradycardia, hypothermia | Dry; track marks; pulmonary oedema (heroin) | Miosis + respiratory depression + ↓consciousness |
| Sedative-hypnotic | Benzodiazepines, barbiturates, ethanol, GHB, z-drugs | Sedation, ataxia → coma | Normal | Hypothermia (mild), hypotension, respiratory depression | Dry; alcohol smell | Normal pupils + CNS depression |
| Serotonin syndrome | SSRIs, SNRIs, MAOIs, tramadol, linezolid, fentanyl, St John's wort | Agitation, confusion, clonus | Mydriasis or normal | Hyperthermia (mild–severe), tachycardia, hypertension, tachypnoea | Diaphoresis (clammy), hyperreflexia | Clonus (inducible/spontaneous, esp. lower limbs) + hyperreflexia |
| Neuroleptic malignant syndrome (NMS) | Antipsychotics (haloperidol, olanzapine), dopamine-agonist withdrawal | Mutism, stupor, catatonia | Normal | Severe hyperthermia (>38.5°C), tachycardia, labile BP, lead-pipe rigidity | Diaphoresis, sialorrhoea | Lead-pipe rigidity + bradyreflexia + slow onset (days) |
| Withdrawal | Alcohol, benzodiazepines, opioids | Agitation, tremor, seizures | Mydriasis | Tachycardia, hypertension, hyperthermia | Diaphoresis, tremor | History of dependent use + cessation |
References41ShowHide
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