Toxicology and Poison Prevention
Decontamination and general approach
Activated charcoal 1 g/kg (max 50 g) is useful within roughly 1 hour of ingestion when the airway is protected and the toxin adsorbs to charcoal. It is not indicated for hydrocarbons, caustics, alcohols, iron, or lithium, and is contraindicated with altered mental status and unprotected airway. Never induce vomiting, and do not attempt gastric lavage outside very select early presentations.
Antidotes worth memorizing
Acetaminophen: N-acetylcysteine, guided by the Rumack-Matthew nomogram 4 hours after ingestion. Salicylates: urinary alkalinization with sodium bicarbonate, hemodialysis for severe toxicity. Iron: deferoxamine. Lead: succimer or calcium disodium EDTA. Organophosphates: atropine plus pralidoxime. Opioids: naloxone 0.1 mg/kg (max 2 mg) titrated to respirations. Methanol or ethylene glycol: fomepizole. Cyanide: hydroxocobalamin. Methemoglobinemia: methylene blue 1–2 mg/kg, contraindicated in G6PD deficiency. Carbon monoxide: 100% oxygen, hyperbaric in severe cases. Sulfonylurea: octreotide with dextrose. Beta-blocker: glucagon and high-dose insulin. Calcium channel blocker: calcium salts and high-dose insulin with dextrose. Tricyclic antidepressant: sodium bicarbonate for wide QRS.
Pediatric-specific risk
One or two tablets can be lethal to a toddler - tricyclics, calcium channel blockers, sulfonylureas, and opioids are classic examples. Poison prevention counseling should include safe storage and the poison control number.
Worked example
A 12 kg toddler ingests an unknown amount of acetaminophen. Draw a level 4 hours after ingestion. If the level falls above the treatment line, give N-acetylcysteine 150 mg/kg over 1 hour, then 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours.