14.1 Common Pediatric Toxic Ingestions, Poisonings & Antidotes

Common Pediatric Toxic Ingestions, Poisonings & Antidotes

Toxicological emergencies in pediatric transport demand rapid recognition of clinical toxidromes, aggressive stabilization of vital organ systems, and targeted administration of antidotes. Pediatric patients are uniquely vulnerable to toxic exposures because of developmental physiology: immature hepatic microsomal enzymes, lower plasma protein binding, a higher body water-to-lipid ratio, and rapid metabolic rates. When dispatched to transport a poisoned child, transport clinicians must operate with heightened vigilance, anticipating rapid clinical deterioration during transit.

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Pediatric Ingestion Epidemiology: Toddlers vs Adolescents

Toxic ingestions in pediatric medicine divide sharply into two distinct epidemiological cohorts with diametrically opposed clinical patterns:

• Exploratory Ingestions in Toddlers (Ages 1 to 5 Years): Young children account for a large share of all poison center exposure calls. Toddlers explore their environment through hand-to-mouth behavior. Ingestions are almost universally unintentional, occur in home environments, and involve a single substance found in accessible containers (e.g., grandfather's pill organizer, household cleaning agents, brightly colored candies resembling medications). Toddlers typically ingest small volumes or solitary tablets. However, their small body mass makes even minute doses potentially catastrophic.
• Intentional Ingestions in Adolescents (Ages 12 to 18 Years): These ingestions represent intentional self-harm, suicide attempts, or substance experimentation. Adolescents frequently present with polypharmacy, co-ingesting multiple prescription pharmaceuticals, over-the-counter analgesics (acetaminophen, NSAIDs), illicit synthetic compounds, and ethanol. History is frequently unreliable, obscured by shame, altered mental status, or concealment. Transport clinicians must assume polypharmacy until proven otherwise and systematically screen for occult co-ingestions.

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Classical Toxidromes: Transport Clinical Recognition

A toxidrome is a constellation of physical signs and physiological parameters characteristic of a specific drug class. Rapidly mapping a patient's vital signs and physical examination to a toxidrome directs empiric stabilization before confirmatory lab assays are available.

Critical Differentiating Pearl: Anticholinergic vs Sympathomimetic

Both anticholinergic and sympathomimetic toxidromes present with hyperthermia, marked tachycardia, hypertension, and dilated pupils. The critical bedside differentiating sign is sweating (axillary moisture):

• Anticholinergic Toxicity: Muscarinic acetylcholine receptors on sweat glands are blocked. The patient is "dry as a bone" with dry, warm skin and bone-dry axillae and oral mucosa.
• Sympathomimetic Toxicity: Alpha-1 and beta-adrenergic stimulation drives intense diaphoresis. The patient is "soaked in sweat" with drenched axillae and clammy skin.

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'One Pill Can Kill': High-Yield Lethal Single-Dose Ingestions in Toddlers

In a 10-kg toddler, a single adult tablet or small mouthful of certain concentrated compounds can produce fatal cardiovascular collapse, refractory neurotoxicity, or severe metabolic arrest. The transport team must treat any history of these exposures as an immediate intensive care emergency, regardless of initial asymptomatic status.

                    "ONE PILL CAN KILL" IN TODDLERS
  ┌─────────────────────────────────┬─────────────────────────────────┐
  ▼                                 ▼                                 ▼
Sulfonylureas              Calcium Channel Blockers          Beta-Blockers
• Glipizide, Glyburide     • Verapamil, Diltiazem            • Propranolol, Atenolol
• Severe delayed hypo-     • Bradycardia, shock, block       • Bradycardia, cardiogenic shock
  glycemia (up to 48h)     • Hyperglycemia (blocks insulin)  • Lipophilic: crosses BBB (seizures)
  │                                 │                                 │
  ▼                                 ▼                                 ▼
Tricyclic Antidepressants  Clonidine                         Concentrated Opioids
• Amitriptyline            • Central Alpha-2 Agonist         • Methadone, Fentanyl
• Sodium channel block     • Miosis, bradycardia, apnea      • Delayed severe apnea
• Wide QRS, arrhythmias    • Mimics opioid toxidrome         • Prolonged coma

1. Sulfonylureas (Glipizide, Glyburide, Glimepiride): Stimulate pancreatic beta-cell sulfonylurea receptors to trigger endogenous insulin exocytosis. A single tablet causes profound, recurrent hypoglycemia. Onset is notoriously delayed (often 8 to 16 hours, persisting up to 48 hours!).
   • Management: Do not rely solely on IV dextrose boluses (dextrose spikes trigger further reactive insulin release, creating roller-coaster rebound hypoglycemia). The specific antidote is Octreotide (a synthetic somatostatin analog: 1 to 2 mcg/kg IV or SubQ every 6 to 8 hours), which halts pancreatic insulin secretion.
2. Calcium Channel Blockers (CCBs - Verapamil, Diltiazem, Amlodipine): Block L-type calcium channels in the myocardium and peripheral vasculature. They produce catastrophic bradycardia, profound cardiogenic shock, conduction blocks, and arterial vasodilation. Notably, CCBs inhibit calcium-mediated insulin release from pancreatic beta cells, typically presenting with hyperglycemia and lactic acidosis.
3. Beta-Adrenergic Antagonists (Beta-Blockers - Propranolol, Atenolol, Metoprolol): Inhibit beta-1 and beta-2 receptors, causing bradycardia, low cardiac output, and hypoglycemia. Lipophilic beta-blockers (especially Propranolol) cross the blood-brain barrier, block fast cardiac sodium channels, and trigger seizures, coma, and QRS widening.
4. Tricyclic Antidepressants (TCAs - Amitriptyline, Nortriptyline, Imipramine): Ingestions exert multi-receptor toxicity: fast sodium channel blockade, anticholinergic action, alpha-1 antagonism, and GABA inhibition. Electrocardiographic hallmarks include QRS widening >100 ms (predicts seizures) and QRS >160 ms (predicts life-threatening ventricular arrhythmias, including ventricular tachycardia and torsades de pointes), along with a prominent terminal R wave in lead aVR >3 mm.
   • Management: Administer Sodium Bicarbonate (1 to 2 mEq/kg IV bolus), repeated until QRS narrows and serum pH achieves 7.50 to 7.55. Hypertonic sodium increases the extracellular sodium gradient to overcome competitive sodium channel blockade, while systemic alkalinization unbinds the drug from the sodium channel receptor.
5. Clonidine (Central Alpha-2 Agonist): Decreases central sympathoadrenal outflow. In toddlers, clonidine overdose produces a clinical picture that mimics opioid toxicity: pinpoint pupils (miosis), profound bradycardia, hypotension, hypothermia, and periodic central apnea. Naloxone has variable efficacy (~30-50%); primary therapy is supportive airway management, atropine, and vasopressor infusions (dopamine or norepinephrine).
6. Concentrated Opioids (Methadone, Buprenorphine, Fentanyl Patches): Methadone possesses an exceptionally long half-life (24 to 36 hours). Toddlers who ingest liquid methadone or accidentally mouth discarded transdermal fentanyl patches experience sudden, delayed fatal apnea.

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Acetaminophen (APAP) Overdose & N-Acetylcysteine Protocols

Acetaminophen is the most ubiquitous pediatric toxic exposure. At therapeutic doses, 90% of acetaminophen is metabolized via glucuronidation and sulfation in the liver. Approximately 5% is metabolized by hepatic cytochrome P450 2E1 (CYP2E1) into the highly reactive, electrophilic intermediate N-acetyl-p-benzoquinone imine (NAPQI). Under normal circumstances, endogenous glutathione conjugates NAPQI into non-toxic mercapturic acid.

                         ACETAMINOPHEN METABOLISM
                               Acetaminophen
                                     │
             ┌───────────────────────┴───────────────────────┐
             ▼                                               ▼
   Glucuronidation & Sulfation                         CYP2E1 Pathway
   (90% - Saturated in Overdose)                             │
             │                                               ▼
             ▼                                             NAPQI
     Non-Toxic Metabolites                         (Toxic Intermediate)
                                                             │
                             ┌───────────────────────────────┴───────────────────────────────┐
                             ▼                                                               ▼
                   Adequate Glutathione                                           Glutathione Depleted (<30%)
                             │                                                               │
                             ▼                                                               ▼
                     Mercapturic Acid                                            Centrilobular Hepatic
                       (Non-Toxic)                                                 Necrosis & Fulminant
                                                                                   Liver Failure

In overdose, glucuronidation and sulfation pathways become saturated. CYP2E1 shunts large amounts of acetaminophen into NAPQI. Once hepatic glutathione stores are depleted by >70%, free unbound NAPQI binds covalently to hepatocytes, causing centrilobular hepatic necrosis and fulminant liver failure.

The Rumack-Matthew Nomogram Rules

• The nomogram is valid ONLY for acute, single-point-in-time ingestions with known ingestion times.
• It is completely invalid for chronic supratherapeutic ingestions, staggered doses, or extended-release formulations.
• The first serum APAP level must be drawn at 4 hours post-ingestion. Blood drawn earlier than 4 hours cannot be interpreted because hepatic distribution is incomplete, yielding false security.
• The treatment line begins at 150 mcg/mL at 4 hours (1000 µmol/L). Any concentration plotting on or above this line mandates full antidote therapy.

Antidote: N-Acetylcysteine (NAC)

NAC acts as a glutathione precursor and glutathione substitute, directly neutralizing NAPQI and providing antioxidant anti-inflammatory support.

• Standard IV 3-Bag Regimen (Total 300 mg/kg over 21 hours):
  • Bag 1 (Loading): 150 mg/kg IV in D5W infused over 60 minutes.
  • Bag 2 (Second Dose): 50 mg/kg IV in D5W infused over 4 hours.
  • Bag 3 (Third Dose): 100 mg/kg IV in D5W infused over 16 hours.
• Anaphylactoid Reactions: Non-IgE-mediated histamine release occurs in up to 10-15% of patients receiving rapid IV NAC loading (flushing, pruritus, urticaria, bronchospasm). If this occurs during transport: temporarily stop the infusion, administer Diphenhydramine (1 mg/kg IV), and once symptoms resolve, restart the NAC infusion at a slower rate.

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Salicylate Toxicity & Alkalinization Protocol

Salicylates (Aspirin, bismuth subsalicylate, and concentrated methyl salicylate / oil of wintergreen, where 1 teaspoon equals ~21 adult aspirin tablets) produce complex multisystem metabolic chaos:

1. Direct Medullary Stimulation: Salicylates directly stimulate the brainstem respiratory center, causing hyperventilation and a primary respiratory alkalosis.
2. Uncoupling of Oxidative Phosphorylation: In mitochondria, salicylates uncouple oxidative phosphorylation, disrupting ATP production. Cellular metabolism shifts to anaerobic pathways, releasing heat (hyperthermia) and generating excess lactic acid, pyruvic acid, and ketoacids. This produces a primary high-anion-gap metabolic acidosis.
3. Classic Acid-Base Finding: The hallmark of salicylate toxicity is a mixed primary respiratory alkalosis and primary metabolic acidosis.

Transport Management: Urine Alkalinization & Hemodialysis

Salicylate exists in non-ionized (lipid-soluble, crosses the blood-brain barrier) and ionized (lipid-insoluble, trapped in urine/blood) states. Alkalinizing the serum and urine draws salicylate out of tissues into the circulation and traps it in renal tubular lumens ("ion trapping").

• Sodium Bicarbonate Infusion: Add 100 to 150 mEq of Sodium Bicarbonate to 1 liter of D5W; infuse at 1.5 to 2 times maintenance fluid rates. Target urine pH of 7.5 to 8.0 while keeping arterial pH <7.55.
• Mandatory Potassium Repletion: Transport clinicians must aggressively replete potassium (adding 20 to 40 mEq/L KCl to IV fluids). Hypokalemia prevents urinary alkalinization because the renal distal tubule exchanges intracellular hydrogen ions ($H^+$) for potassium ($K^+$); if serum potassium is low, the kidneys excrete acid into the urine, resulting in paradoxical aciduria and locking salicylate inside brain cells.
• Emergent Hemodialysis Indications: Salicylate level >90 to 100 mg/dL acutely, severe refractory metabolic acidosis (pH <7.20), altered mental status or cerebral edema, pulmonary edema, or oliguric renal failure.

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Opioid Overdose & Naloxone Titration in Transit

Naloxone is a pure competitive mu-opioid receptor antagonist that reverses life-threatening respiratory depression and apnea.

• Dosing: 0.01 to 0.1 mg/kg IV, IO, IM, or IN (titrate from small doses up to a standard maximum initial dose of 2 mg; cumulative doses up to 10 mg can be given for synthetic opioids).
• Transport Titration Strategy: The clinical goal of naloxone administration is adequate spontaneous ventilation and airway reflex recovery, NOT full combative wakefulness. Rapid high-dose boluses precipitate severe acute withdrawal, uncontrolled vomiting with aspiration, extreme agitation, and massive sympathetic surges culminating in acute non-cardiogenic pulmonary edema.
• Caution in Opioid-Dependent Patients: In neonates born to chronically opioid-dependent mothers or children on chronic opioid regimens, administer micro-doses (0.005 to 0.01 mg/kg) to avoid acute withdrawal seizures and cardiovascular collapse.
• Continuous Naloxone Infusion: Naloxone has an effective duration of action of only 30 to 90 minutes. Long-acting opioids (e.g., methadone, extended-release formulations) outlast naloxone by many hours. To prevent rebound apnea during prolonged air or ground transport, calculate the total bolus dose that successfully restored spontaneous breathing, and initiate a continuous IV infusion delivering two-thirds of that successful dose per hour.

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Calcium Channel Blocker & Beta-Blocker Overdose: High-Dose Insulin Therapy

When CCBs or beta-blockers cause severe cardiogenic shock refractory to fluid resuscitation and atropine, transport clinicians must initiate specialized pharmacological salvage therapy.

High-Dose Insulin Euglycemia Therapy (HIET)

During shock, the stressed myocardium shifts from free fatty acid oxidation to carbohydrate and glucose metabolism. CCB and BB toxicity impairs pancreatic insulin secretion and induces profound peripheral insulin resistance, starving myocardial cells of energy substrate. HIET provides immense inotropic support without increasing myocardial oxygen consumption or arrhythmogenicity.

                        HIET PROTOCOL FOR CCB / BB SHOCK
  ┌───────────────────────────────────────────────────────────────────────────┐
  │ 1. Regular Insulin IV Bolus: 1 unit/kg                                   │
  │    + Dextrose Bolus: 0.5 - 1 g/kg (e.g., 2 - 4 mL/kg D25W or D10W)        │
  └─────────────────────────────────────┬─────────────────────────────────────┘
                                        │
                                        ▼
  ┌───────────────────────────────────────────────────────────────────────────┐
  │ 2. Regular Insulin Continuous Infusion: 1 unit/kg/hr                      │
  │    (Titrate up to 2 - 10 units/kg/hr if cardiogenic shock persists)       │
  └─────────────────────────────────────┬─────────────────────────────────────┘
                                        │
                                        ▼
  ┌───────────────────────────────────────────────────────────────────────────┐
  │ 3. Dextrose Infusion: D10W or D20W titrated to Euglycemia (100 - 200 mg/dL)│
  │    • Check point-of-care blood glucose every 15 - 30 minutes in transit   │
  │    • Monitor serum potassium; replete ONLY if K+ < 2.5 - 3.0 mEq/L        │
  └───────────────────────────────────────────────────────────────────────────┘

• HIET Dosing: Administer an IV bolus of Regular Insulin at 1 unit/kg along with 0.5 to 1 g/kg of dextrose (2 to 4 mL/kg of D25W, or 5 to 10 mL/kg of D10W in infants). Follow immediately with a continuous regular insulin infusion at 1 unit/kg/hr, titrating up to 2 to 10 units/kg/hr for persistent shock.
• Dextrose Co-Infusion: Run a dedicated D10W or D20W infusion titrated to maintain blood glucose between 100 and 200 mg/dL. Monitor glucose every 15 to 30 minutes.
• Potassium Handling in HIET: Insulin drives potassium into cells. A mild drop in potassium is expected and does not reflect total-body loss. Do not aggressively supplement potassium unless serum $K^+ < 2.5\text{ to }3.0\text{ mEq/L}$, as excessive potassium infusion can induce lethal hyperkalemia once insulin stops.
• Adjunctive Therapies:
  • Calcium Chloride 10%: 20 mg/kg (0.2 mL/kg) via central line or IO, or Calcium Gluconate 10%: 60 mg/kg (0.6 mL/kg) via peripheral line, repeated every 10 to 20 minutes for up to 3 to 4 doses to overcome calcium channel blockade.
  • Glucagon: 0.05 to 0.1 mg/kg IV bolus (maximum 5 to 10 mg) over 1 to 2 minutes, followed by an infusion of 0.05 to 0.1 mg/kg/hr. Glucagon bypasses blocked beta receptors by directly stimulating adenylate cyclase to generate intracellular cyclic AMP (cAMP), augmenting heart rate and contractility.

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Caustic Ingestions: Acids vs Alkalis

Corrosive ingestions represent surgical emergencies where improper transport management can cause fatal airway loss or gastrointestinal perforation.

Strict Contraindications in Transport Management

• NEVER induce emesis: Regurgitating caustic material re-exposes the friable esophagus, pharynx, and airway to chemical destruction and risks pulmonary aspiration.
• NEVER perform gastric lavage or insert blind nasogastric tubes: Blind tube placement through necrotized, friable esophageal mucosa can cause transmural esophageal rupture and mediastinitis.
• NEVER administer chemical neutralizing agents (weak acids or bases): Neutralization reactions are strongly exothermic, generating massive heat that produces severe secondary thermal burns superimposed on chemical injury.
• Airway Evaluation: Immediate visual assessment for stridor, drooling, hoarseness, and dysphagia. If airway edema is present, secure the airway early under direct video laryngoscopy with a surgical airway kit at the bedside.

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Realistic Transport Scenario: Pediatric Toxic Ingestion in Transit

A critical care flight team is dispatched to a remote community clinic to transport a 2-year-old male (weight 12 kg). Two hours prior, the child was found playing with his grandmother's pill bottle containing Verapamil SR (240 mg) and Glipizide (10 mg). Upon the transport team's arrival, the child is lethargic with cool, pale extremities. Vital signs: heart rate 54 bpm, blood pressure 64/38 mmHg, respiratory rate 22 breaths/min, oxygen saturation 96% on room air, and point-of-care blood glucose 242 mg/dL. Capillary refill is 4.5 seconds. A 12-lead ECG reveals sinus bradycardia with first-degree atrioventricular block (PR interval 220 ms).

The team recognizes severe calcium channel blocker toxicity compounded by impending sulfonylurea-induced hypoglycemia (the initial hyperglycemia is driven by CCB blockade of pancreatic insulin exocytosis). The transport team immediately places a proximal tibial IO after peripheral attempts fail. Resuscitation begins with 20 mL/kg of balanced crystalloid (240 mL) and Calcium Chloride 10% (240 mg, 2.4 mL IO) over 10 minutes. Heart rate improves marginally to 62 bpm, but blood pressure remains depressed at 68/40 mmHg.

The flight nurse immediately initiates High-Dose Insulin Euglycemia Therapy: an IV/IO bolus of 12 units Regular Insulin (1 unit/kg) paired with 24 mL of D25W (0.5 g/kg), followed by a continuous regular insulin infusion at 12 units/hr (1 unit/kg/hr). Simultaneously, a maintenance infusion of D10W at 60 mL/hr is started. To prevent delayed, catastrophic hypoglycemia from the glipizide, the team administers Octreotide 15 mcg SubQ (1.25 mcg/kg). During the 45-minute helicopter flight, blood glucose is checked every 15 minutes, remaining stable at 148 to 172 mg/dL. At 30 minutes into the flight, the child's heart rate increases to 98 bpm, blood pressure rises to 88/54 mmHg, and peripheral pulses become palpable. The patient is delivered safely to the pediatric intensive care unit without invasive mechanical ventilation.

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Clinical Pearls for Pediatric Toxic Emergencies