Snake Envenomation

Snake Envenomation is a topic covered in the 5-Minute Emergency Consult.

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Basics

Description

  • Pit viper venom:
    • Mixture of proteolytic enzymes and thrombin-like esterases:
      • Enzymes cause local muscle and subcutaneous tissue necrosis
      • Esterases have defibrinating anticoagulant effect, leading to venom-induced consumption coagulopathy (VICC) in severe envenomations
  • Bite location:
    • Extremity bites most common
    • Head, neck, or trunk bites more severe than bite on extremities
  • Severe envenomation:
    • Direct bite into artery or vein
    • Neurotoxic envenomations
  • Bite mark significance:
    • Pit viper bite: Classically includes 1 or 2 puncture marks
    • Nonvenomous snakes and elapids: Horseshoe-shaped row of multiple teeth marks
  • 25% of all pit viper bites are dry and do not result in envenomation

Etiology

Venomous Snakes Indigenous to the U.S.
  • Pit vipers (Crotalinae):
    • Account for 95% of all envenomations
    • Rattlesnakes, cottonmouths, and copperheads
  • Coral snakes (Elapidae):
    • Neurotoxic
    • Western coral snakes, found in Arizona and New Mexico
    • More venomous eastern coral snakes, found in Carolinas and Gulf states

International Exotic Venomous Snakes
Occur in zoos or in owners of exotic snakes
Pediatric Considerations
  • 30% of all snakebites involve patients younger than 20 yr. 12% of all snakebites are 9 yr or younger
  • Because of their low body weight, smaller children and infants are more vulnerable to severe envenomation with systemic symptoms

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Basics

Description

  • Pit viper venom:
    • Mixture of proteolytic enzymes and thrombin-like esterases:
      • Enzymes cause local muscle and subcutaneous tissue necrosis
      • Esterases have defibrinating anticoagulant effect, leading to venom-induced consumption coagulopathy (VICC) in severe envenomations
  • Bite location:
    • Extremity bites most common
    • Head, neck, or trunk bites more severe than bite on extremities
  • Severe envenomation:
    • Direct bite into artery or vein
    • Neurotoxic envenomations
  • Bite mark significance:
    • Pit viper bite: Classically includes 1 or 2 puncture marks
    • Nonvenomous snakes and elapids: Horseshoe-shaped row of multiple teeth marks
  • 25% of all pit viper bites are dry and do not result in envenomation

Etiology

Venomous Snakes Indigenous to the U.S.
  • Pit vipers (Crotalinae):
    • Account for 95% of all envenomations
    • Rattlesnakes, cottonmouths, and copperheads
  • Coral snakes (Elapidae):
    • Neurotoxic
    • Western coral snakes, found in Arizona and New Mexico
    • More venomous eastern coral snakes, found in Carolinas and Gulf states

International Exotic Venomous Snakes
Occur in zoos or in owners of exotic snakes
Pediatric Considerations
  • 30% of all snakebites involve patients younger than 20 yr. 12% of all snakebites are 9 yr or younger
  • Because of their low body weight, smaller children and infants are more vulnerable to severe envenomation with systemic symptoms

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