One Pill Can Kill: Advancing Your Knowledge of Pediatric Toxicology

'One Pill Can Kill' is a new online column covering cases of pediatric toxicology.

Sick children can be terrifying—none more so than the undifferentiated sick child. While most of us have a standard approach to sick children—mine is airway, breathing, circulation, don’t forget to check the glucose—there are so many pediatric conditions that are rare, we can’t possibly be considered experts in caring for critically ill children.

While cases involving adult toxicology often start with known exposures, child toxicities are often more occult. The reasons for this are many: Children require smaller doses to cause poisoning, are less able to communicate their exposure, may not know they were exposed to a toxin, and are more likely to mistake poisons for food.

Further, children are more susceptible to harm from poisons. Their smaller mass, higher metabolic rates, and different pharmacokinetics mean just a small amount of a poison—a teaspoon of some liquids or a single pill from grandma’s cabinet—can cause morbidity and death.

The result? The poisoned child may go undiagnosed unless clinicians maintain a high index of suspicion.

In this series we’ll review an approach to the poisoned child and develop a differential diagnosis for single pills and low-volume liquids that can cause severe toxicity. Welcome to One Pill Can Kill.

The Case of the Sweet Little Boy

Saturday, 15:14

You're called to a private residence for 2-year-old boy, unconscious and breathing. You arrive to a quaint residence with wallpaper circa 1952. An elderly woman meets you at the front door. Frantic, she guides you through the foyer and into the living room, where you find a previously healthy child weighing approximately 26 pounds. The grandmother is babysitting him this weekend for the first time so his parents can take a vacation.

On exam he is pale, diaphoretic, and spontaneously breathing. Capillary refill peripherally is delayed, and his extremities are cool. You see no other abnormalities. Vitals are heart rate 176, respiratory rate 30, BP 72/42, SpO₂ 95%.

A survey of the living room identifies a tidy room with locked liquor cabinet. A blister packet of pills is on the sofa.

Prep time:

• List five differential diagnoses for this unconscious child;
• What is your approach to the child with a potential unknown ingestion?
• What are your next three steps once arriving at the patient’s side?

The blister pack is riddled with pills—you suspect the grandmother is poorly compliant and may have cognitive impairments. The list of pills reads:

• ASA
• Amitriptyline
• Metoprolol
• Glibenclamide
• Clopidogrel
• Rosuvastatin
• Omeprazole
• Diltiazem
• Nifedipine
• Hydromorphone

The child has a capillary glucose reading of 1.4, and his ECG shows sinus tachycardia.

A Useful Mnemonic

Use the mnemonic ABC GET MOM to remember toxins that can kill a child in small doses. The list isn’t exhaustive but covers many of the common medications that can harm children.

• Antimalarials
• Beta blockers
• Clonidine, calcium channel blockers
• Glyburide (or another sulfonylurea)
• Ethelene glycol (antifreeze)
• Tricyclic antidepressants (amitriptyline)
• Methanol (nail polish remover)
• Opioids (hydromorphone)
• Methyl salycilates (oil of wintergreen)

An Approach to Pediatric Toxicology

Step One: The Interview

The interview should include the following questions:

• What was ingested? Were there any coingestions?
• When was it ingested?
• How much was ingested?

Step Two: The Exam

Look for toxidromes and other presentations that can help narrow down causative agents. This child has hypoglycemia, which has its own toxicological differential and often causes altered consciousness. Toxic causes of pediatric hypoglycemia include sulfonylureas, beta blockers, ethanol, ACE inhibitors, acetaminophen, monoamine oxidase inhibitors (MAOIs), and trimethoprim/sulfamethoxazole (TMP-SMX).

Conclusion

You suspect this child has overdosed on glyburide. Like all sulfonylureas, glyburide can cause hypoglycemia, which will transiently respond to glucose administration. After assessing for aspiration risk, determine if oral glucose, intramuscular glucagon, or intravenous dextrose is the most appropriate therapy. Keep in mind that when administering dextrose to children, D10 or D25 mixes are preferred to D50. D25 is easy to prepare in the field by expelling half the amp of D50 and drawing up an equal amount of saline.

Improvements should be rapid, but beware: They may be transient should the toxic effect of glyburide continue. Children should be monitored in a hospital and may require dextrose infusions or other supportive therapies.

After a decade working as a helicopter paramedic, Blair Bigham, MD, MSc, EMT-P, completed medical school in Ontario, Canada, where he is now a ED resident. E-mail him at blair.bigham@medportal.ca.