Snake Envenomation

Basics

Description

  • Pit viper venom:
    • Complex mixture of organic compounds (proteins, lipids, biogenic amines, etc.)
    • Metalloproteinases, serine proteases, phopholipase A2, disintegrins, bradykinin-potentiating peptides, and C-type lectin-like proteins constitute primary toxic components
    • Leads to tissue destruction, inflammation, and hemorrhage
  • Bite location:
    • Extremity bites most common
    • Head, neck, or trunk bites often more severe than bite on extremities
  • Severe envenomation:
    • Anaphylactoid and anaphylactic reactions:
      • Often from direct intravascular envenomation
    • Neurotoxic envenomation
  • Bite mark significance:
    • Pit viper bite: Classically includes 1 or 2 puncture marks:
      • Absence of puncture wound does not rule out envenomation
    • Nonvenomous snakes and elapids: Horseshoe-shaped row of multiple teeth marks
  • 20% of all pit viper bites are dry and do not result in envenomation

Etiology

Venomous Snakes Indigenous To The Us

  • Pit vipers (Crotalinae):
    • Account for 95% of all envenomation
  • Rattlesnakes, cottonmouths, and copperheads
  • Coral snakes (Elapidae):
    • Neurotoxic
    • The more venomous Eastern coral snake is found in the Southeast, east of the Mississippi River
    • Less venomous species are found in Texas and Arizona, west of the Mississippi

International Exotic Venomous Snakes

  • Occur in zoos or in owners of exotic snakes

Pediatric Considerations

  • 30% of all snakebites involve patients <20 yr old. 12% occur in those <9 yr old
  • Because of their low body weight, smaller children and infants are more vulnerable to severe envenomation

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