Snake bites

Background

  • An average of 5000 native venomous snakebites are reported to US poison centers annually[1]
  • 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).[2]
  • 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 no 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

Evaluation

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
    • Antivenom is first line treatment for compartment syndrome; fasciotomy is last resort if elevated pressures persist.

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 [3]
  • Compartment syndrome has been documented with crotaline envenomation, but current literature does not support use of fasciotomy. [4] Treatment should focus on antivenom.

Antivenom

Disposition

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

See Also

References

  1. Seifert SA et al. AAPCC database characterization of native U.S. venomous snake exposures, 2001-2005. Clin Toxicol (Phila). 2009;47: 327–335.
  2. Goldfranks Toxicology - Envenomations
  3. Gold B.. Bites of venomous snakes. N Engl J Med. 2002;347(5):347-56.
  4. Cumpston KL. Is there a role for fasciotomy in Crotalinae envenomations in North America? PMID: 21740134