What are the symptoms, signs, and treatment options for viper, sea snake, and cobra bites, including management of neurotoxic, hemotoxic, and myotoxic complications?

Snake Bite Management: Symptoms, Signs, and Treatment for Viper, Sea Snake, and Cobra Bites

Immediate medical attention is essential for all venomous snake bites, with specific management strategies based on the type of envenomation (neurotoxic, hemotoxic, or myotoxic) and snake species involved. 1

Clinical Presentation by Snake Type

Viper Bites (Hemotoxic)

• Local symptoms:
  • Immediate pain and progressive swelling
  • Ecchymosis and tissue necrosis
  • Fang marks (though presence alone doesn't confirm envenomation) 2
• Systemic symptoms:
  • Coagulopathy (bleeding from gums, hematuria)
  • Thrombocytopenia (occurs in ~30% of cases) 2
  • Hypotension
  • Acute kidney injury
  • Nausea, dizziness, weakness 2

Cobra Bites (Neurotoxic)

• Local symptoms:
  • Minimal local tissue damage
  • Mild pain and swelling
• Systemic symptoms:
  • Descending paralysis (starting with ptosis, facial muscles)
  • Respiratory compromise
  • Difficulty swallowing
  • Muscle weakness
  • Respiratory failure (can occur within 12-30 hours if untreated) 1

Sea Snake Bites (Myotoxic/Neurotoxic)

• Local symptoms:
  • Minimal local reaction
  • Subtle fang marks
• Systemic symptoms:
  • Myalgia and muscle stiffness
  • Rhabdomyolysis
  • Myoglobinuria (dark urine)
  • Renal failure
  • Neurotoxic effects (similar to cobra bites)

Emergency Management

First Aid (Pre-Hospital)

1. DO:

   • Call emergency services immediately
   • Rest and immobilize the bitten extremity
   • Remove constricting jewelry
   • Keep bite site below heart level if possible 1

2. DO NOT:

   • Apply ice
   • Use suction devices
   • Apply electric shock
   • Use tourniquets
   • Use pressure immobilization bandaging (for North American pit vipers) 1

Hospital Management

Initial Assessment

• Assess airway, breathing, circulation
• Document time of bite, snake species (if known)
• Mark the advancing edge of swelling
• Obtain vital signs
• Monitor for signs of systemic envenomation

Laboratory Evaluation

• Complete blood count
• Coagulation studies (PT, PTT, fibrinogen)
• Renal function tests (BUN, creatinine)
• Electrolytes
• Urinalysis (for myoglobinuria)
• Cardiac monitoring 1

Treatment by Envenomation Type

1. Hemotoxic Envenomation (Vipers)

• Antivenom administration:
  • CroFab (Crotalidae Polyvalent Immune Fab) is the standard treatment
  • Initial dose: 4-6 vials administered as soon as possible 1
  • Additional doses until initial control is achieved (when local injury progression stops, systemic symptoms resolve, and coagulation parameters normalize) 1
• Supportive care:
  • Aggressive fluid resuscitation with normal saline (initial rate 1000 ml/h, then tapered by at least 50% after 2 hours) 1
  • Avoid potassium-containing fluids due to risk of hyperkalemia 1
  • Blood products for severe coagulopathy
  • Elevation of affected limb
  • Pain management
  • Tetanus prophylaxis 3

2. Neurotoxic Envenomation (Cobras)

• Antivenom specific to elapid species
• Respiratory support:
  • Early intubation and mechanical ventilation at first sign of respiratory compromise
  • Respiratory support may be required for several days 1
  • Monitor oxygen saturation and provide supplemental oxygen if hypoxic 1
• Supportive care:
  • IV fluids
  • Anticholinesterase drugs may help with neuromuscular symptoms

3. Myotoxic Envenomation (Sea Snakes)

• Antivenom specific to sea snake species
• Aggressive hydration:
  • Prevent acute kidney injury from rhabdomyolysis
  • Monitor urine output
• Management of hyperkalemia:
  • IV calcium gluconate
  • Insulin with glucose
  • Consider emergency dialysis if refractory 1

Complications and Monitoring

Short-term Complications

• Compartment syndrome (rare, fasciotomy only if confirmed)
• Acute kidney injury
• Respiratory failure
• Severe coagulopathy
• Anaphylaxis to antivenom 4

Long-term Complications

• Chronic kidney disease (up to 3.4% in some snake species) 5
• Chronic wounds (0.7%)
• Amputations (0.7%)
• Psychological sequelae (0.6%) 5

Follow-up Monitoring

• Monitor for recurrent coagulopathy for at least one week following treatment 1, 4
• Patients who experience coagulopathy during initial hospitalization are at risk for recurrence 4
• Long-term follow-up is essential as persistent renal involvement may occur in up to 41% of patients 1
• Risk of progression to chronic kidney disease in approximately 5-20% of cases 1

Special Considerations

Antivenom Administration

• Test for hypersensitivity before administering (though skin testing is not required) 4
• Have emergency medications ready (epinephrine, antihistamines, albuterol)
• Monitor for acute allergic reactions (urticaria, pruritus, erythema, angioedema, bronchospasm)
• Watch for delayed allergic reactions or serum sickness (rash, fever, myalgia, arthralgia) 4

Contraindications

• Known severe allergic reaction to sheep proteins (for CroFab)
• Allergies to papain, chymopapain, other papaya extracts, or pineapple enzyme bromelain may increase risk of reaction to CroFab 4
• Use caution with repeat courses of antivenom due to sensitization risk 4

By promptly recognizing the type of envenomation and providing appropriate treatment, mortality from snake bites can be significantly reduced. The most critical intervention is early administration of the appropriate antivenom along with supportive care tailored to the specific toxicity profile.