Venomous snake bites are a significant medical emergency in many regions, particularly in tropical countries. Snake venom contains complex mixtures of enzymes, peptides, and toxins that can cause neurotoxic, hemotoxic, or myotoxic effects. Early recognition of envenomation and prompt administration of antivenom are critical for improving patient outcomes.
Common Venomous Snakes
Elapidae (Neurotoxic)
- Cobras
- Kraits
- Coral snakes
Viperidae (Hemotoxic)
- Russell’s viper
- Saw-scaled viper
- Pit vipers
Hydrophiidae (Sea Snakes)
- Sea kraits
- Sea snakes
Types of Venom Actions
Neurotoxic Venom
- Affects neuromuscular transmission
- Causes paralysis of respiratory muscles
Hemotoxic Venom
- Causes coagulopathy and bleeding
- Destroys vascular endothelium
Myotoxic Venom
- Rhabdomyolysis
- Myoglobinuria leading to renal failure
Clinical Features
Local Symptoms
- Pain and swelling
- Bleeding from fang marks
- Bruising and blistering
- Local necrosis (more common in viper bites)
Systemic Neurotoxic Features
- Ptosis
- Diplopia
- Difficulty swallowing and speaking
- Respiratory paralysis
Systemic Hemotoxic Features
- Gum bleeding
- Hematuria
- Prolonged clotting time
- Hypotension and shock
Myotoxic Features
- Muscle pain
- Dark-colored urine (myoglobinuria)
- Acute kidney injury
Investigations
- 20-minute whole blood clotting test (WBCT)
- Complete blood count
- Coagulation profile (PT, INR, aPTT)
- Renal function tests
- Serum creatine kinase (CK)
- Urinalysis
First Aid Measures (Do’s and Don’ts)
Do’s
- Reassure the patient and keep them calm
- Immobilize the affected limb
- Remove tight clothing and jewelry
- Transport the patient to a medical facility promptly
Don’ts
- Do not cut, suck, or apply ice to the bite
- Do not use tourniquets
- Do not apply herbal remedies
- Do not allow the patient to walk
Management
1. Stabilization
- Assess airway, breathing, and circulation
- Start IV access and administer fluids if needed
- Provide oxygen in respiratory distress
2. Antivenom Therapy
- Only specific and definitive treatment for venomous snake bites
- Indicated for systemic envenomation or significant local swelling
- Administered IV after sensitivity testing (as per local protocol)
- Monitor for anaphylaxis during infusion
3. Treatment of Complications
Coagulopathy
- Repeat antivenom if clotting time remains prolonged
- Fresh frozen plasma may be used in severe cases
Neuroparalysis
- Mechanical ventilation if respiratory failure occurs
Acute Kidney Injury
- IV fluids to maintain urine output
- Dialysis if needed
Local Tissue Necrosis
- Wound care and infection prevention
- Debridement in severe cases
Monitoring
- Repeat clotting tests
- Monitor urine output
- Check neurological status regularly
Prevention
- Wear protective footwear in snake-prone areas
- Avoid sleeping on the ground
- Use lights when walking outdoors at night
Detailed Notes:
For PDF style full-color notes, open the complete study material below:
PATH: PHARMD/ PHARMD NOTES/ PHARMD FOURTH YEAR NOTES/ CLINICAL TOXICOLOGY/ VENOMOUS SNAKE BITES.