The epidemiology of pediatric poisonings can be elicited by examining telephone calls made to poison control centers throughout the United States. More than 70% of calls to poison centers involve children under the age of 18 years. Data collected from these centers reveal that:

The most commonly ingested substances in young children in decreasing order of frequency include:

Fatalities from ingestion in children are extremely rare. Data from Poison Centers from 2003 revealed that of the approximate 2.5 million calls to these centers, there were 34 reported fatalities. In children <6 years of age, 12 deaths were associated with over-the-counter products, nine were unintentional, eight were therapeutic errors, seven were environmental exposures, and two were homicides. In adolescents, approximately 40% involved drug experimentation and 33% were suicides.

Plant exposures account for up to 10% of calls to poison centers. The vast majority do not involve more than minimal symptoms. However, because of the large number of these exposures, fatalities can occur. It is therefore useful to know which types of exposures have the potential to cause severe morbidity or mortality. These include:

The history and physical examination are pivotal in the appropriate management of a child who presents after having ingested an unknown substance. Despite rapid advances in technology, a basic knowledge of the presenting features of the major categories of poisonings is critical to appropriate management because management decisions are routinely made before the results of laboratory tests become available. Most pediatric ingestions are unintentional, and in many cases, the poison is an unknown substance, so that it becomes necessary to elicit a thorough history from the parents. A standard history should be obtained, including what agent was ingested, how much, when, why, and under what circumstances. The location of the ingestion may also be helpful. For example, potential agents ingested in the kitchen may be different than those in the bathroom. It is often helpful to have the parents or caregiver bring in the substance. Many cleaning and household products contain multiple potential toxins, and reviewing the label may be useful. In cases of ingestion involving unknown products, the parents, with guidance, can often identify a list of potential toxins and medications in the home. A review of the activities of the past 24 hours can often provide a sense of when the ingestion took place, information that helps to determine the severity of exposure, and whether aggressive therapy is needed. It has been estimated that history is the most important factor in identifying unknown ingestions in up to 90% of cases. Information provided by an ado lescent who has had an intentional ingestion is often unreliable. Use of illicit drugs is typically underreported. A family history of drug use in an older sibling or par ent may often lead to unintentional ingestions in young children.

Unfortunately, the history does not always identify the offending agent, especially in adolescents in whom the ingestion frequently is intentional and unwitnessed. In these situations, the physical examination and a knowledge of toxidromes is crucial because treatment often must be instituted before the results of any laboratory testing are known. Toxidromes can identify the ingested toxin or class of ingested agent in more than 80% of cases of ingestion of unknown toxins. The most commonly encountered toxidromes are summarized in Table 59.1.

Certain substances can be rapidly identified during the physical examination by characteristic odors (Table 59.2) or specific examination findings (Table 59.3). Frequent physical examinations may provide critical information about the evolution of poisoning and the need for aggressive interventions.

Screening laboratory tests are helpful in the management of ingestions because of their easy access and rapid turnaround times. The goal is often to identify the metabolic effects of the poison. However, few are specific.

In most cases, it is easy to calculate an anion gap from the electrolyte values in the emergency setting. The anion gap is calculated with the following formula:

Normal values are <16. An elevated anion gap represents an accumulation of organic acids, such as lactate or formate, which neutralize bicarbonate. However, a normal anion gap does not rule out the presence of organic acids.

An elevated anion gap can be caused by the ingestion of:

Uremia, diabetic ketoacidosis, and lactic acidosis also can cause an elevated anion gap.

An osmolar gap can also be calculated easily from the laboratory values for electrolytes and renal function. An osmolar gap indicates the presence of low-molecularweight toxins, although the absence of an osmolar gap does not rule out the presence of these toxins. The following formula is utilized to calculate an osmolar gap:

If the osmolality calculated with this formula is less than the measured serum osmolality, then an osmolar gap is present.