Introduction and epidemiology

In 2009, the NSW Poisons Information Centre received in excess of 50 000 calls from around Australia regarding paediatric exposures to pharmaceuticals, chemicals, plants and animals. There is a bimodal distribution in the frequency of exposures, with the larger peak occurring in the toddler age group (ages 1–3 years) and a much smaller peak in the mid to late teens. The latter peak relates to deliberate self-poisoning in adolescents. Over eighty percent of poisons centre calls relating to childhood exposures are advised to stay at home as no acute management is necessary. Pharmaceuticals are by far the commonest exposure in children as per American Poison Control Center data. The top ten unintentional exposures in children (under the age of 18 years) reported to Australian Poisons Information Centres are listed in Table 21.1.1. It is important to note that paracetamol is present in many preparations as well as in combination products (e.g. with codeine, pseudoephedrine, doxylamine, dextromethorphan).

Diagnosis

As opposed to overdose in the adult population, exposures in children are nearly always accidental or unintentional. The circumstances around the exposure or ingestion are often unknown or difficult to elucidate. Parents and carers are usually uncertain about time of exposure or dosage of drug ingested. As such, the clear history required to make an accurate risk assessment is difficult or sometimes impossible. Regardless of whether the entire history and circumstances surrounding the exposure are available, it is prudent to plan for a ‘worst-case scenario’, assuming maximal exposure.

Important elements of the focused history include:

Deliberate self-poisoning in adolescents warrants further enquiry into previous ingestions, pre-existing psychiatric illness and management, drug use and social circumstances. In cases of unknown drug exposure, it is important to explore the availability of pharmaceuticals and/or chemicals to which the child may have had access. Plant and mushroom ingestion is common in children and needs to be considered in the acutely unwell child who has been outdoors.

Non-accidental (or deliberate) poisoning of a child requires mandatory reporting to child protection authorities in all jurisdictions within Australia. The index of suspicion is higher in children under the age of 1 year, or where the circumstances of the exposure do not fit the capabilities of the child in question. Rare cases of Munchausen’s syndrome by proxy are also reported in the literature, involving deliberate poisoning of children by their parent/carer.

Physical examination of the potentially poisoned child is usually unremarkable, particularly in asymptomatic children or in the early stage of ED presentation. However, in children presenting with symptoms or patients with altered level of consciousness, a thorough physical examination is vital. Key elements of the toxicological examination include:

Children may also present with a cluster of symptoms and signs suggestive of poisoning, i.e. a toxidrome. Although most cases do not manifest the full spectrum of signs and symptoms, pattern recognition amongst clinicians may provide a clue to diagnosis. Toxidromes and corresponding causative agents commonly seen in children are listed in Table 21.1.2.

SSRI, selective serotonin reuptake inhibitor.

Risk assessment

Following the history and examination of the potentially poisoned child, the clinician must undertake a risk assessment of the likely exposure and probable course of toxicity, if any. This requires knowledge of the toxicodynamics and kinetics of the agents, an understanding of potential complications and experience with previous similar cases. At this stage, it is prudent to obtain advice from expert clinicians in paediatric toxicology, such as through the Australasian Poisons Information Centres (Australia: 13 11 26; New Zealand: 0800 764 766). These centres are available 24/7 and provide expert advice on the assessment and management of poisoning in children. The majority of paediatric exposures do not present to hospital, and even those that do, require observation only. However, there are a few highly toxic pharmaceuticals and chemicals that, even in small doses, can cause severe toxicity. Patients exposed to these select few agents may require close monitoring and potentially aggressive resuscitation – these are discussed in Chapter 21.2.