Distinguish accidental poisoning, intentional overdose, drug abuse (alcohol, solvents), iatrogenic (esp diphenoxylate with atropine (Lomotil) and deliberate poisoning (often no history).
A fast or slow respiratory rate may be a diagnostic clue. Acidotic sighing breathing may indicate metabolic acidosis. Tachycardia, bradycardia, hypertension, hypotension may be diagnostic clues.
If heart rate is above 200 in infant or above 150 in child, or if rhythm is abnormal perform a standard ECG. QRS prolongation and ventricular tachcardia is seen in tricyclic antidepressant (TCA) poisoning.
Fever or hypothermia may be diagnostic clues.
| Signs | Drug |
| Tachypnoea | Aspirin, theophylline, CO, cyanide |
| Bradypnoea | Ethanol, opiates, barbiturates, sedatives |
| Tachycardia | Antidepressants, sympathomimetics, amphetamines, cocaine |
| Bradycardia | Beta blockers, digoxin, clonidine |
| Hypotension | Barbiturates, benxodiazepines, beta blockers, Ca channel blockers, opiates, Fe, Phenothiazines, phenytoin, TCAs |
| Hypertension | Amphetamines, cocaine, sympathomimetic agents |
| Small pupils | Opiates, Organophosphates, phenothiazines |
| Large pupils | Amphetamines, atropine, cannabis, carbamazepine, cocaine, quinine, TCAs |
| Convulsions | Carbamazepine, lindane organophosphates, phenothiazines, TCAs |
| Hypothermia | Barbiturates, ethanol, phenothiazines |
| Hyperthermia | Amphetamines, cocaine, ecstasy, phenothiazines, salicylates |
| Metabolic acidosis | Ethanol, CO, ethylene glycol, Fe, ecstasy, salicylates, TCAs |
| Anion Gap >18 | Ethanol, ethylene glycol, Fe, Methanol, salicylates |
| Hypokalaemia | Beta agonists, theophylline |
| Hyperkalaemia | Digoxin |
If the child has an AVPU score of P his airway is at risk. It should be maintained by an airway manoeuvre or adjunct and senior help requested to secure it.
All children with respiratory abnormalities, shock or a decreased conscious level should receive high flow oxygen through a face mask with a reservoir as soon as the airway has been demonstrated to be adequate.
A number of agents taken in overdose (esp narcotics) can produce repiratory depression. Oxygen should be given but it is important to remember that these patients may have an increasing CO2 level despite a normal oxygen saturation . Inadequate breathing should be supported using a bag-valve-mask device with oxygen or by IPPV in the intubated patient.
A number of poisons can produce shock, by a number of different mechanisms. Iron poisoning causes gastrointestinal bleeding, barbiturates cause vasodilatation. Shock should be treated by fluid bolus, as usual. If possible, inotropes should be avoided in poisoning cases as the combination of toxic substance producing shock and an inotrope may be pro-arrhythmogenic.
Cardiac dysrhythmias can be expected in TCA, digoxin, quinine and anti-arrhythmic drug poisoning. Some anti-arrhythmic treatments are contraindicated with certain poisons. Contact a Poison Centre urgently for advice.
Treat convulsions with diazepam or lorazepam. Give a trial of naloxone in cases where depressed conscious level and small pupils suggest opiate poisoning.
In all cases of serious poisoning early consultation with a Poisons Centre is mandatory. Risks of a particular overdose can be assessed by considering:
Complex or life-threatening cases should be discussed with a Poisons Centre.
If the overdose is assessed as having a potentially high lethality or its exact nature is unknown, then measures to minimise blood concentrations of the drug should be undertaken. Occasionally measures to increase excretion can be emplyed and in some circumstances specific antidotes may be available.
Activated charcoal is capable of binding a number of poisonous substances without being systemically absorbed. However, there are some substances which it will not absorb, including alcohol and Fe. Repeated doses are useful in some types of poisoning because they promote reabsorption from the circulation back into the bowel eg aspirin, barbiturates, theophylline.
It is often difficult to give charcoal to children as it is unpalatable. Flavouring may diminish the charcoal's activity. The charcoal can be given by nasogastric tube or lavage tube after a gastric washout. The dose is at least 10x the estimated weight of poison ingested, usually 25-50g.
Aspirated charcoal causes severe lung damage, so airway protection is especially important in the child who is not fully conscious.
Ipecacuanha is now rarely used. It must not be used in the child with depressed conscious level. Evidence now suggests that unless emesis occurs within 1 hr of ingestion of the poison little will be eliminated. Only about 30% is retrieved before 1 hr. Emesis should only be used for poisons requiring removal which are not bound by charcoal or in children presenting within 1 hr of ingestion who will not take charcoal.
Indicated for children who have ingested significant amounts of drugs at high lethality but is only likely to be effective if performed within 1 hr of ingestion. Intubation under anaesthetic will be necessary for children who cannot protect their airway. After evacuation the lavage tube can be used as a route for a specific antidote or activated charcoal. The lavage fluid can be water or isotonic saline and aliquots of 10-20 ml/kg are used.
Use of haemoperfusion and plasmapheresis should be guided by a Poisons Centre.
If over 20 mg/kg taken, toxicity likely. If over 150 mg/kg, may be fatal. Initial symptoms of toxicity are vomiting, diarrhoea and abdominal pain. Later, drowsiness, fits and circulatory collapse due to gut haemorrhage.
Gastric lavage should be performed once the airway is secured an circulatory access has been gained. Charcoal is not helpful. Desferrioxamine can be left in the stomach, but the main treatment is to infuse desferrioxamine at 15 mg/kg/hr. This should be given to children with serious symptoms such as shock, coma or fits and to all with a serum Fe level at 4+ hrs of 3 mg/l and GI symptoms, leucocytosis or hyperglycaemia.
AXR can show how much iron remains. Whole bowel irrigation with polyethylene glycol solutions may have a place in severe cases.
Cause anticholinergic effects (tachycardia, dilated pupils, convulsions) and cardiac effects (conduction delay, arrhythmia). QRS prolongation >4 small squares is predictive of serious effects.
Convulsions should be treated as usual. Alkalinisation up to arterial pH 7.45 (at least) - 7.5 (preferable) has been shown to reduce cardiac toxicity. Hyperventilate (pCO2 no lower than 3.33 kPa (25 mmHg) and infuse bicarb (1-2 mmol/kg). Hypotension should be treated with volume expansion and if an inotrope is necessary, noradrenaline is superior to others. Glucagon has an inotropic effect and can be used in this circumstance.
The use of antiarrhythmics should be guided by a Poisons Centre.Lignocaine and phenytoin may be helpful (quinidine, procainamide and disopyramide are contraindicated).
Accidental ingestion of paediatric paracetamol elixir prepartions by the toddler very rarely achieves toxicity. Doses of <150 mg/kg will not cause toxicity except in a child with hepatic or renal disease. Oral charcoal should be given and a blood level taken at 4 hrs after ingestion. A nomogram will indicate at what level acetylcysteine should be given intravenously.
Aspirin slows gastric emptying so gastric lavage can be done up to 4 hrs after ingestion. Repeated charcoal doses should be given if sustained release preparations have been ingested. The salicylate level should be measured at 2 hrs, but repeat levels are necessary and no reliance should be placed on a single level. Levels rise over the first 6 hrs (longer if sustained release). Poisoning causes respiratory alkalosis and metabolic acidosis so ABG estimation is needed. Alkalinisation improves excretion of salicylate: 1 mmol/kg of bicarb should be infused over 4 hrs. Forced diuresis is no longer used.
Found in antifreeze and de-icer. Produces clinical appearance of inebriation accompanied by metabolic acidosis and widespread cellular damage, especially to the kidneys. The clue in unwitnessed ingestions is metabolic acidosis with an inexplicable anion gap (Na + K) - (HCO3 + Cl) >18. Activated charcoal is ineffective. Ethanol is a competitive inhibitor of alcohol dehydrogenase and blocks metabolism of the ethylene glycol to its poisonous metabolic byproducts. An oral loading dose of 2.5 ml/kg of 40% ethanol (the strength of most spirits) should be started. Aim for blood ethanol concentration of 100 mg/dl. Haemodialysis may be necessary. Cofactors thiamine and pyridoxine are also recommended.
Local accumulation of noradrenaline and epinephrine leads to tachycardia, which increases myocardial oxygen demand while reducing time for diastolic coronary perfusion. Vasoconstriction causes hypertension and peripheral 5HT receptor stimulation causes coronary artery vasospasm. In addition cocaine stimulates platelet aggregation. Together these changes can produce a coronary event in a child.
Chest pain and various rhythm disturbances are the most frequent complications of cocaine use. Cocaine is also a sodium channel inhibitor so can prolong the QRS duration and impair myocardial contractility.
Initial treatment consists of oxygen administration, continuous ECG monitoring, administration of a benzodiazepine, aspirin and heparin. Hyperthermia should be treated with cooling. Beta blockers are contraindicated. Ventricular tachycardia should be treated with DC shock. Bicarb should be considered.
Most ecstasy tablets contain 30-150 mg of MDMA which stimulates peripheral and central alpha and beta adrenergic receptors with a half life of around 8 hours. Early deaths are usually due to cardiac dysrhythmias while deaths after 24 hours occur from a neuroleptic malignant-like syndrome.
Mild effects include increased tone, agitation, anxiety and tachycardia. Mild elevation of temperature may also occur. At higher doses, hypertonia with hyperreflexia, tachycardia, tachypnoea and visual disturbance can be seen. In the worst affected, coma, convulsions and cardiac dysrhythmias can occur. complications include rhabdomyolysis, metabolic acidosis with acute renal failure and DIC.
Activated charcoal should be given to conscious patients. BP and temperature must be monitored. Diazepam can be used to control anxiety - major tranquillizers should not be used as they exacerbate symptoms. If core temperature exceeds 39 deg C active cooling should be commence and the use of dantrolene (1 mg/kg over 10-15min) should be considered.