Pediatric Poisoning

The occurrence of poisoning in the pediatric population occurs in a bimodal fashion. The first group includes children under 6 years of age who tend to ingest a single substance during normal exploratory behavior. They are generally too young to know what they are doing, and the ingestion is accidental in nature. Adolescents, who make up the second-largest group, often ingest more than one substance intentionally. Their actions may be the result of recreational abuse, attention-seeking behavior or attempted suicide.

The statistics for accidental and intentional exposure to poisons and/or contaminants is staggering. Approximately 2 million cases are reported annually to poison control centers. Of these 2 million reports, 50 percent are in children younger than 6 years.1

The Poison Control Center of The Children's Hospital of Philadelphia covers the Philadelphia metropolitan region, the Delaware Valley and the Lehigh Valley. According to its annual report from July 1999 to June 2000, it received 58,917 calls. Unintentional exposures numbered 39,333. Children under 5 years of age constituted 57.3 percent of the cases. Statistics indicated that 92.5 percent of all pediatric exposures occurred in the home.2

Developmental Issues
Peak incidence for toxic exposures occurs first among toddlers and preschoolers and later among adolescents. It is rare among other age groups, and if seen in young infants, the possibility of abuse must be considered. The most common ingestions are acetaminophen; iron, which is found in a variety of vitamin formulations; tricyclic antidepressants; oral hypoglycemics; street drugs such as PCP, cocaine, etc.; benzodiazepines; caustics; hydrocarbons; and ethanol and toxic alcohols.

"Children will ingest anything that won't ingest them first."3 This statement accurately describes the behavior of curious children under age 6. They learn about the world around them through exploration. Infants quickly progress from playing with their hands in a safe, sedentary position to rolling, crawling and walking by 12-15 months of age.

With mobility comes dangerous curiosity. Household chemicals, over-the-counter medications and prescription drugs in the hands and mouth of a toddler are a recipe for disaster. This age group does not possess the verbal skills to be able to tell parents what they may have eaten and how much.

Preschoolers and toddlers usually ingest a single substance. When treating a child for ingestion where two or more children were playing together, assume that each of the children took the maximum possible dose and treat accordingly.

Adolescents experience multiple challenges during their teen years, including peer pressure and acceptance, altered self-esteem, failed young romance, and risk-taking and attention-seeking behaviors. Ingestions in this age group are often of multiple products. The teens are cognizant that their actions may be suicidal, attention-seeking or recreational.

Exposures are not limited to ingestions. Inhalant abuse among adolescents is a growing problem, along with access to illegal drugs. Suicide or attention-seeking exposures are greater in females than males.4

Emergency Care
When faced with a child or adolescent who demonstrates signs of altered mental status or sudden symmetric neurological symptoms (such as bilateral dilated pupils, new seizures without fever or injury where the story does not fit the picture), it is paramount to keep "ingestion" in the differential diagnosis until proved otherwise. CNS findings include Glasgow Coma Scale score and observation for seizures. A blood sugar check may also provide valuable diagnostic information.

As with the care of any emergency, the initial treatment begins with the ABCs.

- Airway: Position the child to maintain an open airway. Check for a gag and the ability of the child to protect his own airway.

- Breathing: If the child is not breathing effectively or at all, it is necessary to breathe for the child.

- Circulation: Monitor heart rate, blood pressure, ECG and capillary refill.

History Provides Clues
Once the ABCs have been addressed, a history should be obtained including the name and amount of the substance ingested, approximate time of occurrence and if any treatment was performed prior to the patient's arrival at the health care facility. Ask the patient, any family members or available friends, and any EMTs or paramedics involved.

When parents are uncertain of what was ingested, it is recommended that they survey all medications in the house (both prescription and over-the-counter medications) and include all possible storage locations. If necessary, a call to the pharmacy for information on household prescriptions can provide helpful information. Whenever possible, get the container of the agent.

Next, monitor vital signs, looking for evidence of toxidromes (See Table 1). Laboratory studies to consider include: electrolytes, ABG, BUN/creatinine, glucose, anion gap, osmolar gap, liver function tests, CBC and UA. Consider obtaining levels for acetaminophen, iron, aspirin and ethanol and a urine toxicology screen. Keep in mind that toxicology screens only screen for 4-8 common drugs of abuse.

Consider a chest X-ray in patients with tachypnea, hypoxemia and altered mental status. Radiography is useful in detecting pneumothorax and pneumonitis in ingestions of hydrocarbons.

Some empiric drug therapies may be instituted for the symptomatic poisoned child with altered mental status even before absolute identification of the agent. Humidified O2 should be administered to any child with respiratory compromise or hypoxemia. If the rapid dextrose test is low (less than 60) or cannot be performed, then a trial dosage of 0.25-1.0 g of dextrose as a 10-25 percent solution should be administered.

Hypoglycemia can be seen in ingestions of ethanol, oral hypoglycemics, beta-blockers and salicylates.5 Empiric naloxone as a single dose of 1-2 mg can be given to children of all ages (except neonates) with altered mental status and potential poisoning.5 Teens with an opioid toxidrome (see Table 1) without opioid habituation may receive up to 2 mg boluses every 2 minutes up to a total of 8-10 mg.5

Gastric Decontamination
The appropriate method of gastric decontamination is based on time elapsed since the ingestion, the substances ingested and clinical need according to the highest amount that may have been ingested. There are four options for gastrointestinal decontamination.

1. Syrup of ipecac. It is used primarily in the home setting for recent toxic ingestions (i.e., less than 30-60 minutes). The onset of emesis is reliable; however, the amount of drug recovered varies. There are several contraindications for syrup of ipecac, including caustics, corrosives and petroleum distillates; unprotected airways; absent gag reflex; unknown ingestion; and children less than 1 year of age.

2. Lavage. This is not a benign procedure and is rarely performed in pediatric patients. Complications include nasal trauma caused by the insertion of a tube and aspiration of gastric contents with stimulation of the gag reflex during insertion. Lavage should be performed typically within the first hour of the ingestion. Typically, an Ewald tube, a large-bore tube (for children, only a 22-24 French) is used. An acetaminophen gel cap is the largest pill that can be removed using this method.5

3. Charcoal. Activated charcoal is extremely effective in absorbing a wide variety of toxins.1 Activated charcoal effectively binds a variety of toxins therefore preventing their absorption. There are nine ingestion scenarios where it may not be of use (see Table 2). Multiple doses may be used as a method of "intestinal dialysis" for drugs that undergo enterohepatic circulation (carbamazepine, phenytoin, theophylline and phenobarbital).5

To make the charcoal more palatable, it may be flavored with chocolate, coke or cherry syrup and mixed with ice. The dose for charcoal is 1 g/kg and is available as an aqueous mixture or with sorbitol. Sorbitol enhances gastric motility and transmit time through the gut, decreasing the opportunity for absorption. If multiple doses of activated charcoal are given, only the initial dose should contain a cathartic to avoid electrolyte imbalances.

4. Whole bowel irrigation. This is useful in cases of iron, lithium and heavy metal ingestion where charcoal is not effective, as well as for sustained-release products and enteric-coated pills. A solution of polyethylene glycol and electrolytes is given at 20-50 cc/kg/hr to small children and 0.5-1.5 L/hr for adolescents. The end point for the solution is achieved when the effluent is clear.1 This isotonic solution helps to prevent dehydration in infants and children. Several toxicants have additional therapies.

Acetaminophen
Acetaminophen is the most commonly ingested substance in children younger than 6 years.6 Adolescents often present for treatment only after a considerable amount of time has elapsed since the ingestion. An acetominophen level should be obtained within 4-24 hours of ingestion. The nomogram used to predict the range of severity can only be used for levels in this time frame.

N-acetylcysteine (NAC) is the antidote for acetaminophen poisoning and should be initiated within 8 hours of the ingestion at a loading dose of 140 mg/kg po followed by a maintenance dose of 70 mg/kg every 4 hours for 17 doses.7 In order for the patient to tolerate NAC, the 10 percent or 20 percent solution needs to be diluted to 5 percent in juice or soda. Antiemetics such as ondansetron or metoclopramide may be needed to control the nausea and vomiting often associated with NAC administration. Liver function tests should be followed closely in an acetaminophen-poisoned patient.

Iron
Iron ingestion presents a more unique set of challenges in the ED. Iron accounts for 2 percent of all exposures in children under 6 years.6 Estimates of ingested iron are based on the amount of elemental iron ingested, which is calculated by multiplying the amount of iron complex by the percentage of elemental iron in the complex.

Ferrous gluconate has 12 percent elemental iron, ferrous sulfate is 20 percent elemental iron and ferrous fumarate is 33 percent elemental iron. The minimum toxic doses of iron range from 20 mg/kg to 60 mg/kg.7

The clinical course of iron poisoning (stages I-IV) is listed below:

Stage I: Within 6 hours, gastrointestinal losses of blood and fluid may lead to shock and coma. Iron is corrosive and causes hemorrhagic gastroenteritis as well as submucosal thrombi, resulting in mucosal ischemia and necrosis.

Stage II: Some patients may experience an apparent recovery period in mild cases. However, in severe ingestions it is a latent period as the iron is deposited in tissue and organs leading to systemic toxicity. During this time, iron levels may drop as the available iron is deposited in tissue.

Stage III: Systemic toxicity is manifested in multiple organ systems.

Stage IV: Coagulopathy may present as early as 8 hours with prolonged prothrombin levels and partial thromboplastin times.7

Treatment for iron ingestion is supportive with fluid replacement and cardiovascular stabilization. Giving syrup of ipecac within 1 hour post-ingestion can prevent further absorption of iron. Activated charcoal does not bind to iron. Deferoxamine is the iron-chelating drug of choice, binding the iron for excretion in the urine.

Toxic Alcohols
Ethylene glycol and methanol can be found about the house or garage in a variety of forms. Methanol can be found in windshield wiper fluid, antifreeze, gasoline, food warming gel and paint remover. Ethylene glycol is commonly found in antifreeze, inks, adhesives and solvents. Antifreeze has a sweet taste that can make it appealing to children.

It is the metabolites of these substances that are poisonous, so the goal of treatment is blocking their generation. The classic intervention is the use of ethanol, preferably IV, to compete with the enzyme alcohol dehydrogenase. This blocks the metabolism of the toxic alcohol.

Fomepizole (Antizol®, Orphan Medical) is another competitive inhibitor of alcohol dehydrogenase. It is significantly more expensive than ethanol but does not cause the hypoglycemia and change in mental status associated with ethanol. The loading dose is 15 mg/kg, followed by 10 mg/kg q 12 hours. The end point is a serum ethylene glycol less than 20mg/dL.8 Hemodialysis is indicated to clear the toxic alcohol and its metabolites when the ethylene glycol or methanol level exceeds 50 mg/dL, the metabolic acidosis is not immediately corrected with sodium bicarbonate, or the patient has renal failure.

Hydrocarbons
Hydrocarbon poisoning has been reported as the 12th most common poison exposure, resulting in as many as 20 deaths each year.

Hydrocarbons are usually ingested by children less than 5 years old. Simple hydrocarbons such as gasoline, kerosene, furniture polish or lighter fluid are poorly absorbed from the gastrointestinal tract and are dangerous only if aspirated. Pulmonary toxicity results from aspiration. The risk of aspiration is related to the substance's viscosity, volatility, surface tension and chemical activity. Direct mucosal irritation, chemical burns and vomiting increase the risk of aspiration.

Volatile substance abuse by teenagers can cause permanent cardiovascular and neurological damage. Because hydrocarbons are lipophilic they are attracted to neural tissue and can result in acute and chronic CNS and peripheral nervous system toxicity. Volatile agents are acute CNS depressants and are often agents of abuse. High concentrations can sensitize the myocardium to catecholamines and predispose the patient to ventricular tachycardia and ventricular fibrillation.

Oxygen administration and airway management should be administered to all patients with aspiration or airway compromise. Gastric emptying is reserved for those compounds with the potential for systemic effects (carbon tetrachloride, trichloroethane, benzene/toluene) that have toxic additives such as camphor, or ganophosphates or heavy metals, or when a large amount has been consumed.5

Prevention
An ounce of prevention is worth a pound of cure, especially when considering toxic ingestions. The following interventions may be beneficial to share with parents and families:

1. Keep childproof caps on all medications.

2. Keep all chemicals and medications out of children's reach.

3. Maintain childproof locks on storage cabinets for medications and solutions.

3. Use Mr. Yuk stickers, with poison prevention education.

4. Do not store any medications or chemicals in containers other than the original container.

5. Talk with your teens and know who their friends are. Communication may prevent an intentional overdose.

6. Keep Poison Control's phone number next to all phones. The nationwide number to put the caller in touch with their nearest poison control center is 800-222-1222.

Clara Notredame and Debra Westcott are ad vanced practice nurses in pediatric emergency trans port at St. Christopher's Hospital for Children, Philadelphia.


Pediatric Poisoning

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