Snake bites

Background

Coral snake

Rattlesnake

• An average of 5000 native venomous snakebites are reported to US poison centers annually
• In the United States, snake bites can be organized into Crotaline (Pit Vipers) and Elapidae (Coral Snakes)
• Crotalidae family also includes rattlesnakes, Sistrurus and Agkistrodon species (water moccasins and copperheads).
• Risk Factors: "The 'T's" Testosterone, Tequila, Tshirt, Tattoos, Toothless, Teasing, Trailer park, Truck

Venom

• Snake venom is a mixture of proteins, peptides, lipids, and metal ions.
• Many bites can be "dry bites" where not venom is released, about ~1/4

Clinical Features

• Local injury - punctures marks from fangs not always visible, erythema, and edema
• Ooze at fang mark reliable sign of envenomation
• Nausea/vomiting

Differential Diagnosis

Envenomations, bites and stings

• Mammalian bites
  • Closed fist infection (Fight bite)
• Hymenoptera stings (bees, wasps, ants)
• Spider bites
  • Brown recluse
  • Black widow
  • Tarantula
• Scorpion envenomation
• Marine toxins and envenomations
• Snake bites
  • Crotaline (Pit Vipers)
  • Elapidae (Coral Snakes)

Evaluation

• Clinical Diagnosis

Management

Local Care

• Do:
  • Immobilize limb in a neutral position
  • Remove all jewelry
• Do not:
  • Attempt to suck out the venom
  • Place the affected part in cold water
  • Use a tourniquet or wrap

Supportive care

• IVF and pressors if needed for hypotension
• Blood components rarely needed
• Treatment mainly depends upon the presence of an envenomation
• Indications:
  • Progression of local injury - pain, swelling, ecchymosis
  • Coagulopathy - elevated PT/PTT/INR, low fibrinogen, thrombocytopenia
  • Systemic effects - hypotension, altered mental status, nausea and vomiting, paresthesias
• Always provide supportive care and treat local effects of any wounds
• Irrigation of the wound is necessary regardless of the type of snake bite
• Debridement and removal of devitalized tissue may be necessary for severe bites
• Evidence does not support use of empiric antibiotics to prevent secondary infection

Antivenom

• Snake specific treatments depend upon Coral snake or Pit viper envenomations

Disposition

• All snake bites with evidence of envenomations should have a period of observation and possible hospitalization
• Old bites can be assessed an discharged if no evidence of envenomation.

See Also

• Crotaline (Pit Vipers)
• Elapidae (Coral Snakes)

References

Authors

Jordan Swartz, Dr. Jeff Rogers, Jonas McGreggor, Daniel Ostermayer, Lisa Yee, Kevin Lu, Stephen Bogh, Daniel Poon, Ross Donaldson, Michael Holtz, Joel Clinton Miller, Neil Young