CHAPTER 1-2: SPECIAL CONSIDERATIONS IN PEDIATRIC PATIENTS

The majority of calls to poison control centers involve children younger than 5 years. Fortunately, children account for a minority of serious poisonings requiring emergency hospital treatment. Most common childhood ingestions involve nontoxic substances or nontoxic doses of potentially toxic drugs or products. Table I–43 lists important causes of serious or fatal childhood poisoning, which include iron supplements; tricyclic antidepressants; cardiovascular medications such as digitalis (Digoxin and other Cardiac Glycosides), beta receptor antagonists, or calcium antagonists; methyl salicylate (Salicylates); and hydrocarbons.

1. High-risk populations. Two age groups are commonly involved in pediatric poisonings: children between 1 and 5 years and adolescents.

   1. Ingestions in toddlers and young children usually result from oral and tactile exploration. Unintentional exposures in children younger than 6 months or between the ages of 5 and adolescence are relatively rare. In young infants, consider the possibility of intentional administration by an older child or adult. In school-aged children, suspect abuse or neglect.

   2. In adolescents and young adults, overdoses often are the result of suicidal or other self-harm intent, but may also occur in the settings of drug abuse, bullying, underlying mental health conditions, or experimentation. Common underlying reasons for adolescent suicide attempts include pregnancy; sexual, physical, or mental abuse; school failure; conflict with peers; conflict with homosexual orientation; a sudden or severe loss; and alcoholism or illicit drug use. Any adolescent with intentional poisoning must undergo psychiatric evaluation and follow-up.

2. Poisoning prevention. Young children with unintentional exposures are at higher risk for subsequent exposures compared to the general population. After an incident, prevention strategies must be reviewed. If the family does not understand or comply with the advice, or if a child presents with a subsequent poisoning, consider a home evaluation for child-proofing by a public health nurse, child protective services official, or other health care professional.

   1. Enhance child safety in the home, day care setting, and any households the child commonly visits (eg, grandparents and other relatives). Store all medicines, chemicals, and cleaning products out of the reach of children or in locked cabinets. All products should remain in their original containers, and must never be stored in food or drink containers, or in the same cabinets as food. Children commonly find medications and other products on bedside tables, kitchen counters, and in visitors' purses or backpacks.

   2. Use child-resistant containers to store prescription and nonprescription medications. It should be understood that child-resistant containers are not child-proof; they only lessen the time it takes a determined child to get into the container. Children should never be allowed to play with medication containers.

   3. Medication errors are a preventable cause of severe injury or death in children, especially those younger than 1 year. These errors are commonly associated with concentrated drugs in small volumes (<1-mL intended dosages); 10-fold dosing errors secondary to mislabeling or misinterpreted directions; unintentional repeated dosing secondary to multiple caregivers administering the same medication; and unintentional use of more than one product with the same ingredients (ie, a child with fever and cough is given acetaminophen for fever as well as a combination cough medicine that also contains acetaminophen). In one study, the leading causes of death due to medication errors in children were the following: acetaminophen, cough and cold preparations (especially those containing opiates), fosphenytoin, metoclopramide, viscous lidocaine, diphenoxylate/atropine, morphine, digoxin, and sodium phenyl butyrate.

3. Child abuse. Consider the possibility that the child was intentionally given the drug or toxin, or that the exposure occurred as a result of neglect. Most states require all health care professionals to report suspected cases of child abuse or neglect, making it a legal obligation to report any suspicious incident, rather than a discretionary decision. Parents or guardians should be informed in a straightforward, nonjudgmental manner that a report is being made under this legal obligation. Reports of suspected abuse should be made before the child is released, so that local law enforcement or child protection services can decide whether it is safe to release the child to the parents or guardians. In unclear situations, the child can be admitted for observation to allow time for officials to evaluate the social circumstances fully. The following should alert medical personnel to the possibility of abuse or neglect:

   1. Medical, social, of family history that does not make sense or seems inconsistent with the presentation; a recount from a caregiver that changes upon requestioning; or different caregivers providing differing or conflicting accounts of the incident.

   2. The child is nonambulatory, or with very limited access to the poison (eg, a child younger than 6 months, or a child with physical/cognitive disabilities). Carefully review how the child gained access to the drug or toxin.

   3. The child is older than 4–5 years. Accidental ingestions are relatively rare in older children; ingestion may be a signal of abuse or neglect.

   4. The drug ingested was a tranquilizer (eg, haloperidol, chlorpromazine), a drug of abuse (eg, cocaine, heroin), a sedative (eg, diazepam, carisoprodol), or ethanol. On occasion, parents may be simultaneously intoxicated.

   5. There is a long interval between the time of ingestion and the time the child presents for medical evaluation.

   6. There are signs of physical or sexual abuse or neglect: multiple or unusual bruises; a broken bone or burns; a very dirty, unkempt child; or a child with a flat affect or indifferent or inappropriate behavior.

   7. A history of repeated episodes of possible or documented poisonings, or a history of prior abuse.

   8. Munchausen syndrome by proxy: Drugs or toxins are given to the child to simulate or promote illness. Many perpetrators are mothers with a medical background. This is a rare diagnosis.

4. Clinical evaluation. Physical and laboratory evaluation is essentially the same as for adults. However, normal vital signs vary with age (Table I–44).

   1. Heart rate. Newborns may have normal heart rates as high as 190 beats/min, and 2-year-olds up to 120 beats/min. Abnormal tachycardia or bradycardia suggests the possibility of hypoxemia in addition to the numerous drugs and poisons that affect heart rate and rhythm (see Tables I–4, I–5, I–6, I–7).

   2. Blood pressure is a very important vital sign in a poisoned child. The blood pressure cuff must be of the proper size; cuffs that are too small can falsely elevate blood pressure. Blood pressures of infants are difficult to obtain by auscultation, and may more easily be obtained by Doppler in some cases.

      1. Many children tend to have blood pressures lower than that of adults. However, low blood pressure in the context of a poisoning should be regarded as normal only if the child is alert and active, behaves appropriately, and has normal peripheral perfusion.

      2. Idiopathic or essential hypertension is rare in children. Elevated blood pressure should be assumed to indicate an acute condition, although the systolic blood pressure can be transiently elevated if the child is vigorously crying or screaming. Unless a child's baseline blood pressure is known, values at the upper limit of normal should be assumed to be elevated. The decision to treat elevated blood pressure is based on the clinical scenario and the toxin involved.

5. Neonates present specific challenges, including unique pharmacokinetics and potentially severe withdrawal from prenatal drug exposure.

   1. Neonatal pharmacokinetics. Newborns (birth-1 month) and infants (1-12 months) are unique from a toxicological and pharmacological perspective. Drug absorption, distribution, metabolism, protein binding, and elimination may be significantly different from those in older children and adults. Incorrect dosing, trans-placental passage proximate to the time of birth, breast-feeding, dermal absorption, and intentional poisoning are potential routes of toxic exposure. Enhanced skin absorption and reduced drug elimination may lead to significant toxicity after relatively mild exposure.

      1. Skin absorption. Neonates have a very high ratio of surface area to body weight, which predisposes them to poisoning via percutaneous absorption (eg, hexachlorophene, boric acid, or alcohols).

      2. Elimination of many drugs (eg, acetaminophen, many antibiotics, caffeine, lidocaine, morphine, phenytoin, and theophylline) is prolonged in neonates. For example, the half-life of caffeine is approximately 3 hours in adults but may be greater than 100 hours in newborns.

   2. Neonatal drug withdrawal may occur in infants with chronic prenatal exposure to illicit or therapeutic drugs. The onset is usually within 72 hours of birth, but postnatal onset as late as 14 days has been reported. Signs usually commence in the nursery, and patients should not be discharged until clinically stable. However, with early discharge from nurseries being encouraged in many health care settings, an infant's first presentation of withdrawal may be to an emergency department or other outpatient setting. Initial presentation may include nonspecific signs such as mild colic or poor feeding, or may include severe findings such as withdrawal seizures or excessive diarrhea.

      1. Opioids (especially methadone and heroin) are the most common cause of serious neonatal drug withdrawal symptoms. Other drugs for which a withdrawal syndrome has been reported include phencyclidine (PCP), cocaine, amphetamines, tricyclic antidepressants, phenothiazines, benzodiazepines, barbiturates, ethanol, clonidine, diphenhydramine, lithium, meprobamate, and theophylline. A careful drug history from the mother should include exposures to illicit drugs, alcohol, and prescription and over-the-counter medications, and whether she is breast-feeding.

      2. The manifestations of neonatal opioid withdrawal include inability to sleep, irritability, tremulousness, inconsolability, high-pitched incessant cry, hypertonia, hyperreflexia, sneezing and yawning, lacrimation, disorganized suck, poor feeding, vomiting, diarrhea, tachypnea or respiratory distress, tachycardia, autonomic dysfunction, sweating, fevers, and seizures. Morbidity and mortality from untreated opioid withdrawal can be significant, may be associated with weight loss, metabolic acidosis, respiratory alkalosis, dehydration, electrolyte imbalance, and seizures. Withdrawal is a diagnosis of exclusion; other diagnostic considerations include sepsis, hypoglycemia, hypocalcemia, and hypoxia, hyperbilirubinemia, hypomagnesemia, hyperthyroidism, and intracranial hemorrhage. Seizures do not usually occur as the only clinical manifestation of opioid withdrawal.

      3. Treatment of neonatal opioid withdrawal is largely supportive, and includes swaddling, rocking, a quiet room, frequent small feedings with a high-calorie formula, and intravenous fluids or parental nutrition as necessary. A variety of drugs have been used, including morphine, paregoric, tincture of opium, diazepam, lorazepam, chlorpromazine, and phenobarbital. Abstinence-scoring systems may yield objective findings to evaluate and to treat opioid withdrawal. The scoring and treatment of a neonate in withdrawal should be supervised by a neonatologist or pediatric provider experienced with neonatal withdrawal.

6. Pregnancy and drugs or chemicals. The etiology of congenital abnormalities and adverse pregnancy outcomes is multi-factorial; only approximately 1-5% of all defects may be attributable to prescription medications, chemicals, hyperthermia, ionizing radiation, and other reproductive toxins and teratogens.

   1. Adverse effects of drugs and chemicals in pregnancy are dose- and time-dependent. Pregnancy termination is not indicated simply based on exposure to a contraindicated drug. Risks must be carefully considered and evaluated by the patient and health care provider. Although some exposures are associated with well-documented teratogenicity (eg, valproic acid), the majority of drug-exposed fetuses incur little or no adverse effect with close medical monitoring and supervision.

   2. The adverse effects of the drug or chemical on pregnancy or the fetus may include prevention of implantation (eg, nonsteroidal anti-inflammatory drugs [NSAIDs]), fetal death (eg, intra-amniotic methylene blue), malformations (eg, thalidomide), postnatal adverse physiologic effects (eg, oral hypoglycemics), and adverse outcomes that may manifest years after birth (eg, diethylstilbestrol).

      Certain drugs with a very long half-life (eg, ribavirin, retinoids) may require cessation of exposure for several months before conception.

   3. For clinical assistance in determining the risk posed to a pregnancy by a specific exposure, contact Motherisk (www.motherisk.org, 1-877-439-2744 toll-free, or 416-813-6780). Motherisk is an evidence-based information and phone consultation service based in Toronto, Canada devoted to the study of the safety or risk of drugs, chemicals, and disease during pregnancy and lactation.

   4. Breastfeeding. Some drugs can enter breast milk and cause intoxication in the infant. A number of variables determine whether the drug may pose a risk, including its size, lipid solubility, and oral bioavailability. A useful information resource is LactMed (https://toxnet.nlm.nih.gov/newtoxnet/lactmed.htm).

   5. Table I–45 lists the FDA pregnancy ratings of drugs and chemicals (see also Table III-1). Some drugs have more than one pregnancy category because the category changes with the trimester or because different manufacturers/authorities are not in agreement. Briggs GG, Freeman RK, Yaffe SJ. Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk. 9th ed. Lippincott Williams & Wilkins; 2011 provide a comprehensive source of material regarding the effects of drugs and chemicals on pregnancy and lactation. This source organizes data for individual drugs into monographs, with evidence-based recommendations regarding usage and risk. Drugs in pregnancy category D or X, and those noted with additional "risk" or "contraindication" by Briggs et al. are included in Table I–45. Drugs that are labeled FDA category D or X and selected anticonvulsants may still be administered during pregnancy with close medical monitoring and supervision, if the benefits to the mother outweigh the risks to the fetus (maternal benefit >> fetal risk).