Bites, Snake

Key Features

• Venom may be neurotoxic (coral snake) or cytolytic (rattlesnakes, other pit vipers)

• Neurotoxins cause respiratory paralysis; cytolytic venoms cause tissue destruction by digestion and hemorrhage due to hemolysis and destruction of the endothelial lining of the blood vessels

Clinical Findings

• Manifestations of rattlesnake envenomation

  • Local pain

  • Redness

  • Swelling

  • Extravasation of blood

• Other manifestations

  • Perioral tingling

  • Metallic taste

  • Nausea

  • Vomiting

  • Hypotension

  • Ptosis

  • Dysphagia

  • Diplopia

  • Respiratory arrest

• Coagulopathy common and includes prolonged PT and thrombocytopenia (sometimes severe)

Treatment

• Immobilize patient and bitten area in neutral position

• Avoid manipulation of area

• Do not apply ice or tourniquet

• Do not give stimulants

• Incision and suction of bite by unskilled persons probably not useful

• Transport patient to medical facility

Pit viper (eg, rattlesnake) envenomation

• There are two commercially available antivenins for rattlesnake envenomation (CroFab and Anavip)

• CroFab

  • Administered in increments of 4–6 vials in 250–500 mL saline by slow intravenous drip depending on the severity of symptoms

  • Higher doses and additional vials may be required for more serious envenomation with marked local effects and systemic toxicity (eg, hypotension, coagulopathy),

• Anavip

  • Dosage: 10 vials by slow intravenous infusion over 60 minutes initially, followed by additional 10 vial increments as needed for more serious envenomations or for progression of symptoms

  • Monitor vital signs and the blood coagulation profile

  • Type and cross-match blood

• Adequacy of venom neutralization indicated by improvement in symptoms and signs and slowed swelling rate

• Prophylactic antibiotics not indicated

Elapid (coral snake) envenomation

• 1–2 vials of specific antivenom as soon as possible

• Antivenom no longer made in United States; supplies are dwindling

• Call regional poison control center (1-800-222-1222) to locate antisera