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Management of children who have ingested β blockers, digoxin, oral hypoglycaemics, organophosphates, carbon monoxide, cyanide, isopropanol, ethylene glycol, methanol, Ecstasy, LSD, cocaine, nicotine, and isoniazid
In the final paper in this series of articles on the management of poisoning, we deal with exposures to a variety of rare, but potentially very dangerous, toxins.
β BLOCKERS
β Blockers competitively antagonise the binding of catecholamines to β receptors. The effect of specific agents in overdose depends on their receptor specificity, lipid solubility, partial agonist activity, and dose.
Bradycardia and hypotension are the commonest signs of cardiovascular toxicity, but tachycardia and hypertension can occur if a partial agonist is consumed. Other signs of cardiovascular toxicity include varying degrees of heart block, shock, and pulmonary oedema. Central effects can occur, particularly with propanolol, and include lethargy, hallucinations, and convulsions. Hypoglycaemia can also occur.
Asymptomatic children should receive activated charcoal. A period of 12 hours observation is advisable.1 Symptomatic children require intensive monitoring. Hypotension may respond to intravenous fluids. In resistant cases, intravenous glucagon (50–150 μg/kg in 5% dextrose) is the treatment of choice. High dose glucagon stimulates myocardial adenylate cyclase directly, bypassing β receptors. Isoprenaline or cardiac pacing may be required. Regular estimation of blood sugar is essential.
DIGOXIN
Digoxin is potentially extremely toxic in overdose. Children with underlying cardiac disease are particularly at risk and should always receive treatment. Children without a history of heart disease require treatment if they have ingested more than 100 μg/kg body weight.
The toxic effects of digoxin include nausea, vomiting, hypotension, hyperkalaemia, and a multitude of cardiac arrhythmias.2 Careful monitoring is essential as patients can deteriorate suddenly.
Treatment in the first instance is with activated charcoal. Repeated doses should be considered.3 Blood pressure and ECG monitoring are required. Electrolytes should be monitored frequently. Hyperkalaemia should be corrected …