What is the management approach for a patient with suspected rat poison ingestion, particularly those with potential bleeding complications and impaired coagulation?

Management of Rat Poison Ingestion

For suspected rat poison ingestion, immediately prioritize airway, breathing, and circulation support while simultaneously contacting poison control (1-800-222-1222 in the US) for expert guidance, as most modern rat poisons are long-acting anticoagulant rodenticides (LAARs) requiring specific coagulopathy monitoring and vitamin K therapy. 1, 2

Immediate Assessment and Stabilization

• Secure airway, breathing, and circulation first regardless of the specific toxin involved, following standard Advanced Trauma Life Support (ATLS) principles 1, 3

• Contact poison control immediately (1-800-222-1222 in US; 1-800-268-9017 in Canada) for toxin-specific guidance, as management varies significantly based on the active ingredient 1, 2

• Assess for signs of self-harm, abuse, or malicious administration—these patients require immediate emergency department referral regardless of reported dose 2

• Perform rapid assessment for active bleeding (epistaxis, gingival bleeding, bruising, hematuria, gastrointestinal bleeding, intracranial hemorrhage) which mandates immediate ED transfer 2, 4

Critical Distinction: Type of Rat Poison

Long-Acting Anticoagulant Rodenticides (LAARs) - Most Common

This includes brodifacoum, bromadiolone, difenacoum, and related "superwarfarins" which are the predominant rat poisons in modern use 2, 4

Triage Based on Exposure Amount:

• Unintentional ingestion of <1 mg active ingredient: Can be safely observed at home without laboratory monitoring, which includes practically all unintentional pediatric exposures in children <6 years 2

• Unintentional ingestion of ≥1 mg active ingredient: Requires coagulopathy evaluation at 48-72 hours post-exposure with INR measurement 2

• Chronic or repeated ingestion: Immediate ED referral for evaluation of intent and potential coagulopathy 2

• Patients on therapeutic anticoagulants: Obtain baseline prothrombin time immediately, then repeat at 48-72 hours post-ingestion 2

Laboratory Monitoring:

• Measure INR at 36-48 hours post-exposure for all cases except small unintentional pediatric ingestions 2, 4

• If INR is normal at 48 hours, no further action is required even with long-acting formulations 4

• Routine INR measurement is unnecessary in young children with small unintentional exposures based on sufficient safety data 4

Treatment for Coagulopathy:

For active bleeding:

• Administer prothrombin complex concentrate 50 units/kg (contains factors II, VII, IX, X) as first-line therapy 4

• Alternative: Recombinant activated factor VII 1.2-4.8 mg if prothrombin complex unavailable 4

• Fresh frozen plasma 15 mL/kg only if no concentrate available 4

• Phytonadione (vitamin K1) 10 mg IV (100 mcg/kg for children) simultaneously with blood products 4

For elevated INR without active bleeding:

• INR <4.0: No treatment required 4

• INR ≥4.0: Administer phytonadione 10 mg IV 4

• Do NOT give vitamin K prophylactically before coagulopathy is documented 2

Long-Term Vitamin K Management:

• LAARs have extremely long half-lives requiring prolonged vitamin K therapy due to high VKOR affinity 5

• Acute hemorrhagic symptoms often require IV vitamin K1 exceeding 50-100 mg 5

• Chronic maintenance typically requires 100 mg PO vitamin K1 daily to suppress rebound coagulopathy 5

• Average treatment duration is 168 days (approximately 5-6 months) with frequent INR monitoring 5

• Rebound coagulopathy is characteristic of LAAR poisoning after initial treatment cessation 5

• The coagulant effects are not immediate—INR improvement may take 1-8 hours after vitamin K administration 6

Carbamate/Organophosphate Rodenticides - Rare but Life-Threatening

Some illegally imported rodenticides (e.g., "Tres Pasitos" containing aldicarb) cause cholinergic crisis rather than coagulopathy 7

Recognition and Management:

• Presents with cholinergic toxidrome: Salivation, lacrimation, urination, defecation, gastrointestinal distress, emesis, miosis, bronchospasm, bradycardia 7

• Immediate decontamination: Remove contaminated clothing, irrigate skin with soap and water using personal protective equipment 3

• Administer atropine immediately for severe cholinergic manifestations 3

• Early endotracheal intubation for life-threatening presentations 3

• Pralidoxime should be administered early to reactivate acetylcholinesterase 3

• Avoid neuromuscular blockers metabolized by cholinesterase (succinylcholine, mivacurium) 3

Decontamination Considerations

• Do NOT induce vomiting with ipecac syrup 2

• Gastric lavage is NOT recommended 2

• Do NOT delay ED transportation to administer activated charcoal 2

• Activated charcoal is generally not indicated unless specifically advised by poison control 2

• For dermal exposures, wash skin with mild soap and water 2

Critical Pitfalls to Avoid

• Never assume all rat poisons are anticoagulants—illegally imported products may contain carbamates or other toxins requiring completely different management 7

• Bleeding may be delayed for days to weeks after LAAR ingestion, so normal initial presentation does not exclude toxicity 4, 5

• Intracranial hemorrhage is the most common cause of death from LAAR poisoning 5

• Paradoxical thrombosis has been reported with LAAR poisoning, complicating the clinical picture 5

• Failure to respond to vitamin K may indicate congenital coagulation defect or vitamin K-unresponsive condition 6

• Pregnant patients with small unintentional exposures should be evaluated by their obstetrician as outpatient, not requiring immediate ED referral 2

• Repeated large doses of vitamin K are not warranted in liver disease if initial response is unsatisfactory 6

• LAAR poisoning can mimic leukemia, bacterial sepsis, rickettsioses, or other infectious diseases presenting with unexplained bleeding 8