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Salient Features - Pediatric Poisoning (Organophosphate)

Patient Profile

• 3-year-old boy, 14 kg, named Miguel
• Found beside an open, unlabeled pesticide bottle in a rice field
• Route of exposure: dermal (liquid on hands/torso) + likely oral (liquid on lips) + inhalation
• Time since exposure: ~45 minutes

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Identifying the Toxidrome: Cholinergic (SLUDGE/DUMBELS)

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Vital Signs - Red Flags

• HR 54/min - bradycardia (muscarinic effect)
• RR 40/min labored - respiratory distress
• BP 90/60 - borderline hypotension
• SpO₂ 88% on room air - hypoxia (due to bronchospasm + bronchorrhea)

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Investigations - Key Abnormalities

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Summary of Severity Indicators

• Severe OP poisoning based on:
  1. CNS depression (GCS 12, lethargy)
  2. Respiratory failure (SpO₂ 88%, labored breathing, bronchorrhea)
  3. Bradycardia + QTc prolongation
  4. Cholinesterase at only 22% of normal
  5. Mixed acidosis on ABG
  6. Bilateral infiltrates on CXR

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Clinical Framework Implied by the Case

1. ABCDE emergency approach to acute poisoning
2. Identifying the cholinergic toxidrome vs. others (anticholinergic, opioid, sympathomimetic, sedative-hypnotic)
3. Decontamination - removing contaminated clothing, activated charcoal indications
4. Antidote therapy - atropine (to atropinization endpoint) + pralidoxime (oxime reactivator)
5. Disposition and poison-prevention counseling in a Philippine district hospital setting

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Learning Objectives - Explained in Full

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LO 1: Formulate a structured ABCDE emergency approach to the acutely poisoned child, including a focused toxicological risk assessment

A - Airway

• Miguel has copious secretions, drooling, and audible wet breathing - his airway is at immediate risk of obstruction
• Action: Position, suction secretions, prepare for intubation if airway cannot be maintained
• Contaminated clothing must be removed immediately (surface decontamination) before staff touch the patient - OP can absorb through gloves

B - Breathing

• RR 40/min labored, SpO₂ 88%, bronchorrhea, wheeze, crackles
• ABG shows type 2 respiratory failure (PaO₂ 58, PaCO₂ 50, pH 7.28)
• Action: High-flow oxygen, consider early intubation and mechanical ventilation
• Bronchospasm and bronchorrhea are the leading cause of death in OP poisoning

C - Circulation

• HR 54/min (bradycardia), BP 90/60 (hypotension), QTc 470 ms (prolonged)
• Action: IV access x2, cardiac monitoring, IV fluids cautiously (lung already wet)
• Atropine addresses the bradycardia as part of antidote therapy

D - Disability (Neurological)

• GCS ~12, lethargic but rousable, pinpoint pupils, fasciculations, twitching
• Check capillary glucose (done: 6.1 mmol/L - acceptable)
• Assess for seizures (nicotinic/CNS effect of OPs); benzodiazepines are first-line if seizures occur

E - Exposure

• Fully expose the patient - identify all contamination sites (hands, torso, lips)
• Identify the agent, dose, time, and route of exposure = toxicological risk assessment
• In Miguel's case: unlabeled bottle, dermal + oral + possible inhalation, ~45 min ago, toddler with 14 kg body weight = high-risk exposure

Toxicological Risk Assessment

1. What was taken? (OP pesticide - confirmed by odor, miosis, cholinesterase)
2. How much? (Unknown - unlabeled bottle)
3. When? (~45 minutes ago - recent enough for decontamination to help)
4. Route? (Dermal, oral, inhalation - all three)
5. Who? (3-year-old, 14 kg - small body mass = greater toxicity per unit exposure)

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LO 2: Recognize the cholinergic toxidrome and differentiate it from the anticholinergic, sympathomimetic, opioid, and sedative-hypnotic toxidromes

Cholinergic Toxidrome (Miguel's case - OP poisoning)

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Comparison with Other Toxidromes

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LO 3: Apply gastrointestinal and surface decontamination principles, including the indications and contraindications for activated charcoal

A. Surface Decontamination (Priority #1 for OPs)

• Remove all clothing immediately - Miguel's shirt, shoes, everything
• Wash skin thoroughly with soap and water for at least 10-15 minutes
• Wash eyes with normal saline if ocular exposure
• Healthcare workers must wear gloves and gowns - organophosphates absorb through skin and can poison rescuers
• This is often more important than GI decontamination for dermal exposures

B. Gastrointestinal Decontamination

Activated Charcoal (AC)

• Mechanism: Adsorbs the toxin in the gut, preventing absorption
• Standard dose: 1 g/kg (Miguel = 14 kg → 14 g AC)

• Oral ingestion of a toxin that AC adsorbs well (OPs are adsorbed by AC)
• Within 1-2 hours of ingestion (ideally within 1 hour)
• Patient has intact or protected airway

• Depressed consciousness / unprotected airway (risk of aspiration) - this is a concern in Miguel given GCS 12 and secretions; intubation should be secured first
• Caustic/corrosive ingestion (acids, alkalis) - AC does not help and obscures endoscopy
• Hydrocarbon ingestion (high aspiration risk)
• Ileus or bowel obstruction
• Toxins not adsorbed by AC: iron, lithium, heavy metals, alcohols (remembered as PHAILS - Pesticides some, Heavy metals, Alcohols, Iron, Lithium, Solvents)

Gastric Lavage

• Not routinely recommended anymore
• May be considered within 1 hour for life-threatening ingestions if airway is protected
• Risks: aspiration, esophageal perforation, vagal stimulation (worsens bradycardia in OP)

Induced Emesis (Ipecac)

• Contraindicated - no longer used; risk of aspiration, no proven benefit

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LO 4: Select, dose, and titrate specific antidotes - atropine to the atropinization endpoint and pralidoxime - in a pediatric patient

Antidote 1: Atropine

• Initial dose: 0.02-0.05 mg/kg IV (Miguel 14 kg → ~0.3-0.7 mg)
• No minimum dose in children (old teaching of minimum 0.1 mg is no longer standard)
• Double the dose every 5 minutes if not responding
• In severe poisoning, doses can be very large (5-20 mg total or more)

• Do NOT stop atropine just because HR rises - HR is a less reliable guide
• Do NOT over-atropinize - signs of toxicity: hyperthermia, urinary retention, agitated delirium
• Continuous infusion may be needed after initial boluses are achieved

Antidote 2: Pralidoxime (2-PAM, P2AM)

• Loading dose: 20-40 mg/kg IV over 30 minutes (Miguel 14 kg → 280-560 mg)
• Maintenance infusion: 10-20 mg/kg/hour
• Continue for 24-48 hours or until clinical improvement

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LO 5: Interpret focused investigations and monitoring in the poisoned child

Cholinesterase Activity

• RBC cholinesterase is the better marker of clinical severity
• Serial measurements guide when to stop pralidoxime (rising cholinesterase = recovery)

Arterial Blood Gas (ABG)

• pH 7.28 (acidosis), PaO₂ 58 (hypoxia), PaCO₂ 50 (hypercapnia), HCO₃ 20 (low)
• Pattern: Mixed respiratory acidosis (elevated CO₂ from bronchospasm/muscle paralysis) + metabolic acidosis (lactic acid from hypoxia and tissue hypoperfusion)
• Guides: oxygen therapy, ventilation decisions, severity of respiratory failure

ECG

• Sinus bradycardia HR 52 (muscarinic bradycardia)
• QTc 470 ms (prolonged; normal <450 ms in boys)
• QT prolongation in OP poisoning is common and indicates risk of ventricular arrhythmias (Torsades de Pointes)
• Monitor continuously; avoid drugs that further prolong QT (e.g., some antiemetics)

Capillary Blood Glucose

• 6.1 mmol/L - mildly elevated (stress hyperglycemia)
• Important because: hypoglycemia can mimic/worsen CNS depression; must rule out as a treatable cause
• Monitor serially, especially if seizures occur

Chest Radiograph

• Bilateral patchy infiltrates
• Indicates aspiration pneumonitis (from vomiting + secretions + obtunded state) and/or pulmonary edema from bronchorrhea
• Guides ventilator settings; may develop into ARDS

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LO 6: Formulate safe disposition, poisoning-prevention counseling, and appraise the role of the Philippine national poison control system

Disposition Decision

• Admit to Pediatric ICU (PICU) or nearest facility with ventilator capability
• Do NOT discharge any symptomatic OP poisoning patient - symptoms can recur after initial stabilization, especially with fat-soluble OPs that are redistributed
• Monitor for intermediate syndrome (Days 2-4): proximal muscle weakness, respiratory failure after apparent initial recovery, due to persistent nicotinic effects

Poisoning-Prevention Counseling

1. Storage: Pesticides must be kept in original labeled containers, locked away, out of children's reach
2. Never transfer pesticides to food/drink containers (unlabeled bottles are a major cause of accidental ingestion)
3. Supervision: Young children must not have access to agricultural areas unsupervised
4. Protective equipment: Adults handling pesticides should wear gloves, masks, coveralls
5. Disposal: Proper disposal of empty pesticide containers
6. Education: Recognize early signs of OP poisoning - miosis, excessive secretions, vomiting
7. Action: Know what to do - remove from exposure, call poison control immediately

Philippine Poison Control System

• Philippine Poison Control Center (PPCC): The national hotline provides 24/7 expert toxicology advice to patients, families, and healthcare providers
• Based at the Research Institute for Tropical Medicine (RITM)
• Role in this case:
  • Identify the likely pesticide (even without a label)
  • Guide antidote dosing and management in a district hospital that may lack specialists
  • Coordinate transfer if needed
  • Assist in medico-legal documentation
• Hotline: 1-800-1888-7287 (RITM) / (02) 8524-1078
• Pesticide poisoning is one of the most common pediatric toxic exposures in rural Philippines, making this system especially relevant to district hospitals like the one in the case

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Summary Table of All LOs