Toxic exposure occurs frequently in children. Common patterns of pediatric poisoning consist of exploratory ingestions in children < 6 years of age and intentional ingestions and recreational drug use in older children and adolescents.

Toxic exposure should be considered when called to see children who present with

• multi-organ system dysfunction,
• altered mental status,
• respiratory or cardiac compromise,
• metabolic acidosis,
• seizures, or
• an unexplained condition.

The index of suspicion should be high if the child is in the "at-risk" age group (1-4 years of age) and/or has a previous history of ingestion.

Intentional poisoning includes child abuse in young children and suicide attempts in older children/adolescents. Medical child abuse via forced ingestion in young children, particularly those who are younger than one year, must always be on your mind.

 

Toxidromes (TOXIc + synDROMES)

Toxidromes are syndromes of poisoning.

The categories may overlap but, generally, are divided into

1. sympathomimetic and adrenergic blocking agents,
2. cholinergics and anticholinergic,
3. hallucinogenic,
4. opioid,
5. sedative/hypnotic, and
6. serotonin syndrome.

 

Sympathetic Toxidromes

SYMPATHOMIMETIC: substances that stimulate the sympathetic nervous system. These are usually stimulants, causing

• hyperalertness,
• agitation,
• hallucinations, and
• paranoia.

COMMON OFFENDERS:

Cocaine
Amphetamines
Ephedrine
Pseudoephedrine
Theophylline
Caffeine
Cathinones

SIGNS & SYMPTOMS

• Mental status: Hyperalert, agitation, hallucinations, paranoia.
• Vital signs: Hyperthermia, tachycardia, hypertension, tachypnea, widened pulse-pressure, diaphoresis, tremors, hyperreflexia, and seizures.

ADRENERGIC BLOCKING AGENTS:

COMMON OFFENDERS:

• Alpha-adrenergic blockers--oppose the actions of norepinephrine, allowing vessels to remain open.

Used for hypertension. Examples: Doxazosin, Prazosin, Terazosin. S&S: headache, palpitations, weakness, dizziness.

• Beta-adrenergic blockers--for hypertension, arrhythmia, migraines.

Examples: Atenolol, Metoprolol, Nadolol, Propranolol.

SIGNS & SYMPTOMS

Bradycardia and hypotension are the most common effects; also,

• dizziness,
• weakness,
• fatigue,
• cold hands/feet,
• dry mouth,
• headache,
• upset stomach,
• diarrhea/constipation,
• mental status changes,
• hypoglycemia,
• bronchospasm.

Calcium Channel Blockers: work by blocking calcium to relax arterial smooth muscle and block channels in the pericardium.

S&S: flushing (arterial vasodilation), tachycardia, and at higher doses, decreased cardiac inotropy, and bradycardia.

 

Cholinergic and Anticholinergic Toxidromes

CHOLINERGIC: could be called the "Parasympathetic" toxidrome, because it stimulates the parasympathetic nervous system (PNS) by stimulating the receptors for the prime neurotransmitter, acetylcholine.

The PNS is involved in regulatory systems of the body, reflected in the S&S.

COMMON OFFENDERS: 

Insecticides
Nerve agents
Nicotine
Pilocarpine
Physostigmine
Edrophonium
Bethanechol
Urecholine

SIGNS & SYMPTOMS:

• Mental status: Confusion, coma.
• Vital signs: Bradycardia, salivation, incontinence, diarrhea, emesis, diaphoresis, bronchoconstriction, weakness, and seizures.

ANTICHOLINERGIC: competitively compete at the PNS receptors against acetylcholine.

COMMON OFFENDERS:

Antihistamines
Tricyclic antidepressants
Cyclobenzaprine
Anti-Parkinson agents
Phenothiazines
Atropine
Scopolamine
Belladonna alkaloids

SIGNS & SYMPTOMS:

• Mental status: Hypervigilance, agitation, hallucinations, delirium with mumbling speech, coma.
• Vital signs: Dry flushed skin, dry mucous membranes, decreased bowel sounds, urinary retention, myoclonus, picking behavior.

The classic description of anticholinergic poisoning...

Red as a beet (cutaneous vasodilation)
Dry as a bone (inhibits sweat glands)
Hot as a hare (interference with sweating --> hyperthermia)
Blind as a bat (mydriasis--dilation)
Mad as a hatter (delirium, hallucinations)
Full as a flask (full bladder due to reduced contractions and closed sphincter)

 

Hallucinogenic Toxidromes

COMMON OFFENDERS:

Phencyclidine
LSD
Mescaline
Psilocybin
Designer amphetamines (e.g., MDMA, MDEA)

SIGNS & SYMPTOMS:

• Mental status: Hallucinations, perceptual distortions, depersonalization, synesthesia, agitation.
• Vital signs: Nystagmus.

 

Opioid Toxidromes

OPIOIDS:

Heroin
Morphine
Methadone
Oxycodone
Hydromorphone
Hydrocodone
Diphenoxylate

SIGNS & SYMPTOMS:

• Mental status: CNS depression, coma.
• Vital signs: Hyporeflexia, pulmonary edema, needle marks.

 

Sedative/Hypnotic Toxidromes

SEDATIVE/HYPNOTICS: 

Benzodiazepines (Valium, Xanax)
Barbiturates
Carisoprodol (Soma)
Meprobamate
Glutethimide
Alcohols
Zolpidem

SIGNS & SYMPTOMS

• Mental status: CNS depression, confusion, stupor, coma.
• Vital signs: Hyporeflexia.

 

Serotonin Syndrome

SEROTONIN Syndrome: A potentially life-threatening condition of excess serotonin, caused by SSRI (serotonin-reuptake inhibitor) toxicity and other drug interactions and excesses.

COMMON OFFENDERS: 

Monoamine Oxidase Inhibitors (MAOIs)
SSRI (serotonin reuptake inhibitors, e.g., Prozac, Zoloft, etc.)
Meperidine (Demerol)
Dextromethorphan
Tricyclic antidepressants
L-tryptophan

SIGNS & SYMPTOMS: 

• Mental status: Confusion, agitation, coma.
• Vital signs: Tremor, hyperthermia, myoclonus, hyperreflexia, clonus, diaphoresis, flushing, trismus, rigidity, diarrhea, goosebumps.

 

Over-the-Counter Medications

Antihistamines 

S&S: at low doses, sedation; at higher doses, anticholinergic poisoning.
Flushed and dry skin, hyperthermia, blurry vision, agitation, tremor, seizures.

Alpha-1 adrenergic decongestants

S&S: hypertension, tachycardia, mydriasis, diaphoresis, agitaion.

Antipyretic and analgesics (acetaminophen, ibuprofen, aspirin)'

S&S: nausea, vomiting, lethargy, malaise, right upper quadrant pain, and possible liver failure → death.

Antitussives (Cough Suppressants): Cough and cold medications that contain dextromethorphan are commonly used recreationally by youth and adults.

S&S: euphoria, laughing, psychosis, agitation, coma, tachycardia, mydriasis, nystagmus, diaphoresis, zombie-like gate.

OTC cough and cold medications have been associated with fatal overdose in children younger than two years of age.

Expectorant (guaifenesin)

Guaifenesin is relatively safe, causing mild gastrointestinal irritation, but in OTC medications, guaifenesin is usually combined with other ingredients, which can lead to bronchospasm, gastrointestinal disturbance, and fever.

Ethanol in adult formulations: given to children, can cause hypoglycemia.

Ethanol-containing products other than alcoholic beverages (e.g., perfumes, colognes, mouthwash, and ethanol-based hand sanitizers) account for 85-90% of these exposures.

Ethanol-based hand sanitizers, applied liberally, often, or to large skin areas, can cause systemic absorption of ethanol. Ethanol intoxication typically masks the tachycardia, dilated pupils, and diaphoresis commonly associated with hypoglycemia.

• S&S: CNS depression, seizures caused by hypoglycemia (especially infants and young children).

Camphor: used topically for cough and nasal decongestion, some types combine it with menthol (e.g., Vick’s Vaporub). Toxicity can occur from oral or topical ingestion.

S&S: seizures (may be the first sign of exposure!), N&V, agitation, confusion, hyperreflexia, lethargy, or coma.

 

Common Toxic Substances in Abuse

Poison need not be exotic or a controlled drug to kill. Salt, pepper, legitimately prescribed drugs, over-the-counter drugs, and even water can cause toxicity when part of abuse.

Munchausen-by-proxy is when a parent has a psychiatric disorder that drags his or her child into their own hypochondriac paranoia.

• Water: forced water-drinking resulting in hyponatremia, causing seizures, vomiting, coma, or death. It can be administered as punishment and signs of other abuse are frequently present as well.
• Salt: typically in the first 6 months of life, with hypernatremia.
• Aspirin: Salicylate toxicity is known as "salicylism." It can be acute, chronic, or acute-on-chronic. It is rare in children.

S&S: hyperpnea, tachypnea, metabolic acidosis, and possible tachycardia.

• Early symptoms are tinnitus, vertigo, nausea, vomiting, and diarrhea; 
• more severe intoxication can cause fever, altered mental status, coma, pulmonary edema, and death.
   
• Acetaminophen: "the forgotten poison." In taking a history, caregivers may neglect to include acetaminophen due to its OTC status that misleads them to think it's not important.

Rapid identification of acetaminophen toxicity is essential because the antidote, N-acetylcysteine (NAC), is most effective when given within 8-10 hours of an acute acetaminophen ingestion.

S&S: nausea, vomiting, lethargy, malaise, right upper quadrant pain, and possible liver failure → death.

 

Caustic Substances

Half of the millions of toxic exposures to caustic agents are in children < 5 years. The most commonly ingested caustic substances were cleaning products (11%).

ACID pH < 2: causes esophageal injury by coagulation necrosis. This coagulation self-limits the exposure, making perforation less common than with alkali exposure. Upper airway injuries are more common with ingestion of acids because of their bad taste which stimulates gagging, choking, and attempts to spit out the ingested material.

ALKALI pH > 11.5: causes esophageal injury by liquefaction necrosis, with deep penetration and even perforation. Depth of injury depends on time of exposure.

Button batteries in the esophagus can cause rapid injury to the esophagus and critical surrounding structures, due to leakage of alkaline material.

S&S: The most common symptom is dysphagia, even from mild esophageal injury.

 

Inhalations

The lungs provide a rich vascular bed for ingesting toxic substances. Toxic substances get into the body quickly and bypass the liver detoxification. Inhalation is also used as a method of drug abuse.

The lungs, crucial to ventilation/respiration, when damaged by inhaled caustic substances,  can damage them, impairing oxygenation.

The most common identifiable causes of inhalation lung injury are exposure to occupational and environmental agents, especially to inorganic or organic dusts.

The leading injury in the upper airway is thermal injury, resulting in erythema, ulcerations, and edema. Damage of ciliary function impairs movement of substances out of the airway, with an increased risk of bacterial infection.

Injury to the tracheobronchial tree is usually caused by chemicals in smoke or by steam, as well as by toxic inhalation of noxious gases (e.g., chlorine) or liquids (e.g., acid).

Carbon monoxide is one of the most frequent immediate causes of death following inhalation injury.

Caveat: Pulse oximetry cannot screen for carbon monoxide exposure, since it can't differentiate carboxyhemoglobin from oxyhemoglobin due to the color similarity of both in the blood.

Cyanide poisoning is rapidly lethal unless treated with antidote.

Treatment for it should be considered for anyone treated for smoke inhalation or who display depressed level of consciousness, cardiac arrest, or cardiac decompensation in the absence of laboratory confirmation.

 

Assessment

HISTORY: time of ingestion/exposure, amount ingested, abnormal symptoms, bottles/containers available.

PHYSICAL FINDINGS: all vitals, airway/breathing/circulation, pupils.

Also, note diaphoresis, mental state, and any fever.

Rapid evaluation of

1. mental status,
2. vital signs, and
3. pupils

...enables classification of the patient into a state of:

• physiologic excitation (e.g., central nervous system stimulation and increased temperature, pulse, blood pressure, and respiration);
• depression (depressed mental status and decreased temperature, pulse, blood pressure, and respiration); or
• mixed physiologic state.

This initial characterization helps to direct initial stabilization efforts and provides a clue to the etiologic agent.

PUPILLARY CHEATSHEET: 

• MYDRIASIS (pupil dilation):
  • sympathomimetics (phenylephrine, pseudoephedrine, decongestants);
  • antihistamines;
  • anticholinergics;
  • hallucinogens (usually);
  • serotonin syndrome.
• MIOSIS (pupil constriction):
  • choninergics;
  • opioids.
• Sedatives/hypnotics may cause either mydriasis or miosis.

 

Management

CAVEAT: Assume the worst. For example, if a bottle is empty or only has a few pills left, assume it was full before the incident. 

POISON CONTROL CENTER

Role of the Poison Control Center: Any toxic exposure should work in tandem with the Poison Control Center, which is the most authoritative consulting service.

1-800-222-1222

BLOOD GLUCOSE

• Ethanol: Rapid measurement of blood glucose should be performed in all patients, especially infants and young children, with altered mental status.

If low, blood glucose should be corrected and then serially monitored, particularly in cases of younger children or others with limited glycogen stores who may be at risk for recurrent hypoglycemia.

Caveat: With anti-hypertensives,

• hyperglycemia occurs more often with calcium channel blocker toxicity,
• while beta blockers are associated with hypoglycemia.

DECONTAMINATION

Gastrointestinal decontamination: removing an ingested toxin to decrease its absorption. This can be done directly or indirectly.

• Direct is via inducing vomiting or lavage, but these are no longer recommended.

Gastric lavage has been abandoned. Induced vomiting (Syrup of Ipecac) is no longer recommended.

• Indirect is via nasogastric binding with activated charcoal or by speeding up transit time through the GI tract to quicken elimination via feces.

Cathartics: speeding rectal elimination is not recommended.

Dilution: no longer recommended.

Activated charcoal is best used within an hour of ingestion. It should not be used with mental status changes, due to risk of aspiration.

It doesn't work well with metals (iron, lithium), alkali, mineral acids, or alcohols.

Aspiration is the concern most often cited when clinicians choose not to administer activated charcoal.

Rx: Children up to one year of age: 10 to 25 g, or 0.5 to 1.0 g/kg.

Rx: Children 1 to 12 years of age: 25 to 50 g, or 0.5 to 1.0 g/kg (maximum dose 50 g).

Rx: Adolescents and adults: 25 to 100 g (with 50 g representing the usual adult dose)

Topical Irrigation: best for skin and eye exposures. Immediate water irrigation is the essential first aid for chemical burns of the skin and eye, reducing the risk for chronic conjunctivitis and sight-threatening corneal ulceration.

For the eyes, copious irrigation with water dilutes and removes the large majority of chemicals. Moderately warm water, high volume but low pressure should be used for irrigation.

High-pressure irrigation should be avoided, which can splash the corrosive. A topical analgesic to an eye may be needed to irrigate.

For the skin, a much longer period of irrigation is necessary for alkali than for acid exposure: 2 hours or more of continuous irrigation may be required before the pH of tissue exposed to a strong alkali returns to neutral.

Antidotes: Antidote administration is appropriate for poisons that have antidotes and:

• the severity of poisoning warrants it,
• benefits outweigh risks, and there are
• no contraindications.

Dialysis: removes the toxic metabolites of methanol and ethylene glycol, corrects acid-base abnormalities, and reduces end-organ damage and mortality associated with these poisonings.

Hemoperfusions: uses a charcoal membrane between passing blood out and back into the body.

Oxygen and Bronchodilators: for inhalation injuries.

In the field, supportive care is the cornerstone of the treatment of the poisoned patient. However, there are instances in which prompt administration of an antidote can be life-saving.

Naloxone:

Rx: Administer naloxone to patients with signs, symptoms, or a history of opioid intoxication. 

Naloxone is not recommended for neonatal resuscitation because data is lacking regarding its safety, dosing, and effectiveness.