Phys · pharmacological

Poisoning — Approach, Decontamination and Antidotes

Also known as poisoning · overdose · toxicology · toxidrome · sympathomimetic toxidrome · anticholinergic toxidrome · cholinergic toxidrome · opioid toxidrome · sedative-hypnotic toxidrome · SLUDGE · DUMBELS · activated charcoal · whole bowel irrigation · urinary alkalinisation · multi-dose activated charcoal · antidote · naloxone · flumazenil · N-acetylcysteine · fomepizole · pralidoxime · digoxin Fab antibodies · sodium bicarbonate · deferoxamine · hydroxocobalamin · octreotide · lipid emulsion

Consultant-physician-depth guide to the systematic approach to the poisoned patient — ABCDE resuscitation, toxidrome identification (sympathomimetic, anticholinergic, cholinergic, opioid, sedative-hypnotic), gastrointestinal decontamination (activated charcoal, whole bowel irrigation), enhanced elimination (urinary alkalinisation, multi-dose charcoal, haemodialysis), and the antidote reference table. Structured for FRACP DWE and DCE preparation.

high10 referencesUpdated 11 July 202626 min readVerification in progress

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Red flags

A patient who has taken an unknown overdose and whose conscious state is deteriorating — secure the airway before giving charcoal; an unprotected airway is the single most dangerous contraindication to decontamination
Sodium bicarbonate is the specific antidote for tricyclic antidepressant cardiotoxicity — a wide QRS (over 100 ms) and right-axis deviation of the terminal R wave in aVR signal sodium-channel blockade and impending ventricular dysrhythmia
Pinpoint pupils with respiratory depression respond to naloxone — give it titrated (0.04–0.4 mg) to respiratory effort, not to full consciousness, to avoid precipitating acute withdrawal
A high anion gap metabolic acidosis with an elevated osmolar gap is a toxic alcohol until proven otherwise — give fomepizole before the level returns; the osmolar gap falls as the parent alcohol is metabolised
Organophosphate poisoning causes a cholinergic crisis (SLUDGE/DUMBELS, miosis, bronchorrhoea) — atropine dries secretions but does not reverse muscle fasciculations; add pralidoxime early, before the acetylcholinesterase ages irreversibly
Sulfonylurea-induced hypoglycaemia rebounds after dextrose because dextrose stimulates further insulin release — give octreotide to suppress insulin secretion
Local anaesthetic systemic toxicity presents as CNS excitation then seizures and cardiovascular collapse — stop injecting, call for help, and give 20% lipid emulsion early
A mixed respiratory alkalosis and high anion gap metabolic acidosis is the classic early pattern of salicylate toxicity — alkalinise the urine and dialyse for severe toxicity

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FRACP DWEFRACP DCEMRCP Part 1MRCP Part 2MRCP PACESABIM Internal Medicine

Red flags

A patient who has taken an unknown overdose and whose conscious state is deteriorating — secure the airway before giving charcoal; an unprotected airway is the single most dangerous contraindication to decontamination
Sodium bicarbonate is the specific antidote for tricyclic antidepressant cardiotoxicity — a wide QRS (over 100 ms) and right-axis deviation of the terminal R wave in aVR signal sodium-channel blockade and impending ventricular dysrhythmia
Pinpoint pupils with respiratory depression respond to naloxone — give it titrated (0.04–0.4 mg) to respiratory effort, not to full consciousness, to avoid precipitating acute withdrawal
A high anion gap metabolic acidosis with an elevated osmolar gap is a toxic alcohol until proven otherwise — give fomepizole before the level returns; the osmolar gap falls as the parent alcohol is metabolised
Organophosphate poisoning causes a cholinergic crisis (SLUDGE/DUMBELS, miosis, bronchorrhoea) — atropine dries secretions but does not reverse muscle fasciculations; add pralidoxime early, before the acetylcholinesterase ages irreversibly
Sulfonylurea-induced hypoglycaemia rebounds after dextrose because dextrose stimulates further insulin release — give octreotide to suppress insulin secretion
Local anaesthetic systemic toxicity presents as CNS excitation then seizures and cardiovascular collapse — stop injecting, call for help, and give 20% lipid emulsion early
A mixed respiratory alkalosis and high anion gap metabolic acidosis is the classic early pattern of salicylate toxicity — alkalinise the urine and dialyse for severe toxicity

Poisoning — Approach, Decontamination and Antidotes

The answer first

Poisoning is a resuscitation problem before it is a toxin-identification problem. The patient who has collapsed after an unknown ingestion is killed by airway loss, hypoxia, aspiration and dysrhythmia — not by the delay in naming the drug. The registrar who stabilises first, then hunts the toxidrome, then deploys decontamination and antidotes in the correct order will manage any overdose. The one who reaches for the antidote before securing the airway will lose the patient ^[1].

The sequence is fixed and reproducible: ^[1]

Resuscitate — ABCDE. Protect the airway; intubate early if the conscious state is falling. Give oxygen, glucose (check a bedside level first), thiamine in the malnourished or alcoholic patient, and naloxone titrated to respiratory effort when the pupils are pinpoint.
Identify the toxidrome — the constellation of vital signs, pupil size, skin, bowel sounds and mental state that fingerprints a class of toxin. The toxidrome narrows the differential faster than any blood test.
Decontaminate — activated charcoal within one hour of a charcoal-binding ingestion, provided the airway is protected. Whole bowel irrigation for iron, lithium, sustained-release formulations and body packers.
Enhance elimination — urinary alkalinisation for salicylates; multi-dose charcoal for carbamazepine, phenobarbital, theophylline; haemodialysis for salicylates, lithium, methanol, ethylene glycol and metformin.
Give the specific antidote — naloxone, N-acetylcysteine, fomepizole, digoxin Fab, atropine plus pralidoxime, sodium bicarbonate for tricyclic cardiotoxicity, deferoxamine, hydroxocobalamin, octreotide, lipid emulsion. ^[1]

The single most dangerous error in poisoning is giving activated charcoal to a patient with an unprotected airway. Aspiration of charcoal into an unprotected bronchial tree causes a devastating chemical pneumonitis and is frequently fatal. Secure the airway first; decontaminate second ^[3].

Viva trap: "What is the first thing you do for a patient found collapsed beside empty bottles?" Lead with the answer: "I secure the airway and breathing, check a bedside glucose, and only then consider decontamination. Activated charcoal is contraindicated until the airway is protected." ^[1]

References10Show

[1]Erickson TB, Thompson TM, Lu JJ The approach to the patient with an unknown overdose Emerg Med Clin North Am, 2007.PMID 17482020
[2]Kraut JA, Mullins ME Toxic Alcohols N Engl J Med, 2018.PMID 29342392
[3]Chyka PA, Seger D, Krenzelok EP, Vale JA Position paper: Single-dose activated charcoal Clin Toxicol (Phila), 2005.PMID 15822758
[4]Benson BE, Hoppu K, Troutman WG, et al. Position paper update: gastric lavage for gastrointestinal decontamination Clin Toxicol (Phila), 2013.PMID 23418938
[5]Thanacoody R, Caravati EM, Troutman WG, et al. Position paper update: whole bowel irrigation for gastrointestinal decontamination of overdose patients Clin Toxicol (Phila), 2015.PMID 25511637
[6]American Academy of Clinical Toxicology; European Association of Poisons Centres and Clinical Toxicologists Position statement and practice guidelines on the use of multi-dose activated charcoal in the treatment of acute poisoning. American Academy of Clinical Toxicology; European Association of Poisons Centres and Clinical Toxicologists J Toxicol Clin Toxicol, 1999.PMID 10584586
[7]Proudfoot AT, Krenzelok EP, Vale JA Position Paper on urine alkalinization J Toxicol Clin Toxicol, 2004.PMID 15083932
[8]Juurlink DN, Gosselin S, Kielstein JT, et al. Extracorporeal Treatment for Salicylate Poisoning: Systematic Review and Recommendations From the EXTRIP Workgroup Ann Emerg Med, 2015.PMID 25986310
[9]Decker BS, Goldfarb DS, Dargan PI, et al. Extracorporeal Treatment for Lithium Poisoning: Systematic Review and Recommendations from the EXTRIP Workgroup Clin J Am Soc Nephrol, 2015.PMID 25583292
[10]Fasano CJ, O'Malley G, Dominici P, Aguilera E, Latta DR Comparison of octreotide and standard therapy versus standard therapy alone for the treatment of sulfonylurea-induced hypoglycemia Ann Emerg Med, 2008.PMID 17764782

Poisoning — Approach, Decontamination and Antidotes

high10 referencesUpdated 11 July 202626 min readVerification in progress

The answer first

The sequence is fixed and reproducible: ^[1]

Resuscitate — ABCDE. Protect the airway; intubate early if the conscious state is falling. Give oxygen, glucose (check a bedside level first), thiamine in the malnourished or alcoholic patient, and naloxone titrated to respiratory effort when the pupils are pinpoint.

Identify the toxidrome — the constellation of vital signs, pupil size, skin, bowel sounds and mental state that fingerprints a class of toxin. The toxidrome narrows the differential faster than any blood test.

Decontaminate — activated charcoal within one hour of a charcoal-binding ingestion, provided the airway is protected. Whole bowel irrigation for iron, lithium, sustained-release formulations and body packers.

Enhance elimination — urinary alkalinisation for salicylates; multi-dose charcoal for carbamazepine, phenobarbital, theophylline; haemodialysis for salicylates, lithium, methanol, ethylene glycol and metformin.

Give the specific antidote — naloxone, N-acetylcysteine, fomepizole, digoxin Fab, atropine plus pralidoxime, sodium bicarbonate for tricyclic cardiotoxicity, deferoxamine, hydroxocobalamin, octreotide, lipid emulsion. ^[1]

Viva trap: "What is the first thing you do for a patient found collapsed beside empty bottles?" Lead with the answer: "I secure the airway and breathing, check a bedside glucose, and only then consider decontamination. Activated charcoal is contraindicated until the airway is protected." ^[1]

References10Show

[1]Erickson TB, Thompson TM, Lu JJ The approach to the patient with an unknown overdose Emerg Med Clin North Am, 2007.PMID 17482020
[2]Kraut JA, Mullins ME Toxic Alcohols N Engl J Med, 2018.PMID 29342392
[3]Chyka PA, Seger D, Krenzelok EP, Vale JA Position paper: Single-dose activated charcoal Clin Toxicol (Phila), 2005.PMID 15822758
[4]Benson BE, Hoppu K, Troutman WG, et al. Position paper update: gastric lavage for gastrointestinal decontamination Clin Toxicol (Phila), 2013.PMID 23418938
[5]Thanacoody R, Caravati EM, Troutman WG, et al. Position paper update: whole bowel irrigation for gastrointestinal decontamination of overdose patients Clin Toxicol (Phila), 2015.PMID 25511637
[6]American Academy of Clinical Toxicology; European Association of Poisons Centres and Clinical Toxicologists Position statement and practice guidelines on the use of multi-dose activated charcoal in the treatment of acute poisoning. American Academy of Clinical Toxicology; European Association of Poisons Centres and Clinical Toxicologists J Toxicol Clin Toxicol, 1999.PMID 10584586
[7]Proudfoot AT, Krenzelok EP, Vale JA Position Paper on urine alkalinization J Toxicol Clin Toxicol, 2004.PMID 15083932
[8]Juurlink DN, Gosselin S, Kielstein JT, et al. Extracorporeal Treatment for Salicylate Poisoning: Systematic Review and Recommendations From the EXTRIP Workgroup Ann Emerg Med, 2015.PMID 25986310
[9]Decker BS, Goldfarb DS, Dargan PI, et al. Extracorporeal Treatment for Lithium Poisoning: Systematic Review and Recommendations from the EXTRIP Workgroup Clin J Am Soc Nephrol, 2015.PMID 25583292
[10]Fasano CJ, O'Malley G, Dominici P, Aguilera E, Latta DR Comparison of octreotide and standard therapy versus standard therapy alone for the treatment of sulfonylurea-induced hypoglycemia Ann Emerg Med, 2008.PMID 17764782