Toxicology and poisoning in the ICU

ABCDE approach to poisoning

1. 1

   Airway — protect first

   Decreased GCS = aspiration risk. Intubate if the patient cannot protect the airway. Salicylate intubation has been strongly discouraged; McDonald 2024 (11/32 intubated) found mean pH change −0.02 (95% CI −0.11 to 0.07) and no severe complications up to 6 h — this challenges the avoid-intubation paradigm but does not licence underventilation. EXTRIP: AMS is itself an ECTR indication (1D).

2. 2

   Breathing — oxygenation and ventilation

   Assess for respiratory depression (opioids, benzodiazepines) vs hyperventilation (salicylates cause respiratory alkalosis). Give naloxone (initial 0.4-2 mg titrated to adequate ventilation) if opioid suspected (pinpoint pupils). Do NOT give flumazenil routinely — randomised evidence shows it increases serious adverse events including convulsions.

3. 3

   Circulation — haemodynamic support

   Bradycardia/hypotension: consider beta-blocker, calcium channel blocker, TCA, digoxin. Give IV fluids. Vasopressors if refractory.

4. 4

   Disability — GCS, pupils, glucose

   Check glucose immediately (hypoglycaemia mimics many toxidromes). Pupils: pinpoint = opioid (naloxone); dilated = sympathomimetic (amphetamines, cocaine), TCA, anticholinergic. Assess for toxidromes (see below).

5. 5

   Exposure and Environment

   Temperature: hyperthermia (serotonin syndrome, NMS, anticholinergic, salicylates) vs hypothermia (opioids, sedatives). Remove all clothes, inspect for signs of drug use (needle tracks), check whole body for transdermal patches (fentanyl, clonidine).

6. 6

   Decontamination

   Activated charcoal (single dose about 50 g in adults) may be considered if a potentially toxic amount of an adsorbable toxin was ingested within 1 hour AND the airway is intact or protected — it is not recommended routinely. Do NOT give if: unprotected decreased GCS (aspiration), caustic ingestion, hydrocarbons.

7. 7

   Enhanced elimination and antidotes

   Urine alkalinisation (sodium bicarbonate to urine pH 7.5 or higher): first-line for moderately severe salicylate poisoning not needing haemodialysis; also phenobarbital (though multidose charcoal is superior), chlorpropamide, methotrexate. Haemodialysis: salicylates, lithium, metformin, toxic alcohols. Antidotes: NAC (paracetamol), naloxone (opioids), sodium bicarbonate (TCA), fomepizole/ethanol (toxic alcohols), digoxin Fab (digoxin), atropine/pralidoxime (organophosphates).