What is the treatment for snake bite-induced Thrombotic Microangiopathy (TMA)?

Treatment of Snake Bite-Induced Thrombotic Microangiopathy (TMA)

The mainstay of treatment for snake bite-induced thrombotic microangiopathy (TMA) is antivenom administration in a hospital setting with close monitoring for complications, followed by supportive care including management of acute kidney injury. 1

Initial Management

• Immediate care:

  • Call emergency services immediately
  • Rest and immobilize the bitten extremity to reduce venom spread
  • Remove rings and other constricting jewelry from the affected limb
  • Apply a pressure immobilization bandage (40-70 mmHg for upper extremity, 55-70 mmHg for lower extremity) to slow venom spread, but avoid using it for North American pit vipers 1

• Avoid ineffective or harmful interventions:

  • Do not apply suction to the bite area (no clinical benefit and may worsen injury) 2, 1
  • Do not apply ice, electric shock, or tourniquets 1

Hospital-Based Management for TMA

1. Antivenom Administration

• Administer appropriate antivenom as soon as possible in a monitored setting 1
• Monitor for adverse reactions including anaphylaxis or hypersensitivity reactions

2. Laboratory Monitoring

• Complete blood count to assess for:
  • Microangiopathic hemolytic anemia (presence of schistocytes)
  • Thrombocytopenia (platelet count <150 × 10⁹/L or >25% decrease from baseline) 3
• Coagulation studies to evaluate for venom-induced consumption coagulopathy
• Renal function tests to assess for acute kidney injury
• LDH and haptoglobin levels to monitor hemolysis 4

3. Management of Acute Kidney Injury

• Maintain adequate hydration
• Monitor urine output and renal function
• Initiate renal replacement therapy (hemodialysis) if indicated by:
  • Progressive increase in serum creatinine
  • Fluid overload
  • Electrolyte abnormalities
  • Uremic symptoms 4, 5

4. Consideration of Plasma Exchange

• Consider therapeutic plasma exchange (plasmapheresis) in cases with severe TMA not responding to antivenom and supportive care 6, 7
• While evidence is limited, some case reports suggest benefit in severe cases 6, 7
• No definitive evidence exists for routine use of plasma exchange 3

5. Monitoring for TMA Complications

• Monitor for at least 12 weeks after discontinuation of treatment for signs of TMA complications 8
• Signs of TMA complications include:
  • Changes in mental status
  • Seizures
  • Decrease in platelet count by ≥25%
  • Increase in serum creatinine by ≥25%
  • Increase in serum LDH by ≥25% 8

Special Considerations

Complement Inhibition Therapy

• In severe cases of TMA not responding to conventional therapy, complement inhibitors like eculizumab might be considered, though this is not standard practice and would be an off-label use 8
• If used, patients must receive meningococcal vaccination prior to treatment and follow REMS requirements 8

Long-term Follow-up

• Patients with snake bite-induced TMA are at risk for chronic kidney disease
• Regular follow-up of renal function is recommended 3
• Monitor for long-term complications including hypertension and proteinuria

Treatment Algorithm

1. Administer appropriate antivenom as soon as possible
2. Perform comprehensive laboratory assessment (CBC, coagulation studies, renal function)
3. Provide supportive care with IV fluids
4. Monitor for development of TMA (schistocytes, thrombocytopenia, renal dysfunction)
5. If TMA develops:
   • Continue supportive care
   • Initiate hemodialysis if indicated
   • Consider plasma exchange in severe cases not responding to standard therapy
6. Arrange long-term follow-up for monitoring of renal function

While some case reports suggest benefit from plasma exchange in severe cases 6, 7, the most recent comprehensive review indicates there is no definitive evidence for its routine use 3. The cornerstone of treatment remains early antivenom administration followed by supportive care with close monitoring for complications.