Management of rat killer ingestion in peds
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Here is a comprehensive management guide for rat killer (rodenticide) ingestion in pediatrics:
Rat Killer (Rodenticide) Ingestion in Pediatrics
Types of Rodenticides
The vast majority (~80%) of exposures are superwarfarins (second-generation anticoagulant rodenticides). Others include non-anticoagulant agents.
ANTICOAGULANT RODENTICIDES (Most Common)
Agents
- First-generation (warfarin-type): Warfarin — short half-life (~42 hrs); low toxicity with a single small exposure
- Second-generation (superwarfarins): Brodifacoum, bromadiolone, difenacoum, coumafuryl, diphacinone, chlorophacinone — half-life ~120–150 days; effects can persist for weeks to months after a single ingestion
Mechanism
Competitive inhibition of vitamin K → impaired hepatic synthesis of clotting factors II, VII, IX, X → coagulopathy + capillary fragility
Clinical Features
- May be asymptomatic for up to 72 hours after ingestion
- Bleeding manifestations: ecchymosis, epistaxis, gingival bleeding, hemarthrosis, menorrhagia, hematuria
- Life-threatening: massive GI bleeding, intracranial hemorrhage
Management by Scenario
1. Small Accidental Ingestion (Child tasting 2–3 pellets)
- Most common pediatric scenario — unlikely to cause significant toxicity
- No immediate treatment required
- Obtain baseline INR
- Repeat INR at 24 and 48 hours post-ingestion
- Can be discharged home with outpatient follow-up in 48–72 hours
- Do NOT give vitamin K prophylactically
2. Large / Intentional Ingestion
Decontamination:
- Activated charcoal (10:1 charcoal:poison ratio) if < 1 hour from ingestion
- Do NOT perform gastric lavage — risk of inducing GI bleeding with orogastric tube insertion
Investigations:
- CBC (Hgb/Hct, platelets)
- PT/INR and PTT
- Blood type and screen/crossmatch (if bleeding)
- INR may not be abnormal until 48 hours post-ingestion — a normal INR at 48 hours essentially excludes significant ingestion
- Brodifacoum level available at reference labs (>4–10 ng/mL indicates exposure)
Antidote — Vitamin K₁ (Phytonadione):
- Use vitamin K₁ only (not K₃ or K₄ — ineffective and potentially toxic)
- Do not give prophylactically — administer only if INR >2.0
- Takes ~6 hours to take effect; dose every 6 hours
- Pediatric dose: 1–5 mg/day PO in 2–4 divided doses (adults: 20 mg/day)
- Severe/massive overdose may require up to 800 mg/day and treatment for weeks
- Outpatient monitoring of coagulation profile may be required for 4–6 weeks (superwarfarins)
Active Bleeding:
- Packed RBCs for blood loss
- Fresh frozen plasma (FFP)
- Four-factor prothrombin complex concentrate (PCC) — first-line for rapid reversal
- Recombinant activated Factor VIIa — also beneficial
No role for enhanced elimination (dialysis, urinary alkalinization)
3. Disposition
| Scenario | Disposition |
|---|---|
| Small accidental (2–3 pellets) | Discharge + outpatient INR at 48–72 h |
| Large/intentional ingestion | Admit ≥48 h; check INR at 48 h minimum |
| Active coagulopathy | Admit until bleeding resolved, on vitamin K regimen |
| Self-harm/suicide attempt | Psychiatric consult once medically stable |
NON-ANTICOAGULANT RODENTICIDES (Less Common but More Dangerous)
| Agent | Mechanism | Clinical Effects | Treatment |
|---|---|---|---|
| Strychnine | Glycine antagonism at spinal cord | "Awake seizures," risus sardonicus, opisthotonus, hyperthermia, rhabdomyolysis | Benzos/barbiturates, neuromuscular blockade; avoid lavage (precipitates seizures) |
| Zinc/Aluminum phosphide ("rice tablet") | Releases phosphine gas; inhibits electron transport chain | Delayed pulmonary edema/ARDS, GI, cardio, neurologic, refractory hypotension, metabolic acidosis | Benzos for seizures, steroids for adrenal dysfunction, Mg for arrhythmias; observe ≥72 h |
| Sodium fluoroacetate (1080) | Blocks Krebs cycle (fluorocitrate) | Seizures, lactic acidosis, cardiac dysrhythmias, pulmonary edema | Activated charcoal, seizure/arrhythmia control; glycerol monoacetate, Ca gluconate; toxicology consult |
| Barium carbonate | Blocks K⁺ channels → severe hypokalemia | GI, muscle weakness, arrhythmias, paralysis, respiratory failure | Activated charcoal with MgSO₄ or Na₂SO₄; aggressive K⁺ replacement |
| Arsenicide | Binds sulfhydryl groups | GI, cardiovascular collapse, seizures, peripheral neuropathy | Activated charcoal + chelation (succimer, dimercaprol) |
| Thallium sulfate | Mitochondrial sulfhydryl binding, oxidative phosphorylation disruption | Alopecia, GI, neuropathy | Prussian blue (antidote); supportive |
Key Pearls for Pediatrics
- The overwhelming majority of pediatric rat poison exposures are superwarfarin compounds from accidental small ingestions — significant toxicity is rare
- Never check INR before 48 hours — it will be falsely normal and can miss evolving coagulopathy
- Vitamin K₁ is the antidote — only initiate if INR is elevated, not prophylactically
- For phosphide rodenticides, patients must be observed ≥72 hours for delayed pulmonary effects
- Always contact Poison Control for guidance
— Tintinalli's Emergency Medicine, p. 1349 | Rosen's Emergency Medicine, p. 3036
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