Snake Bites
Article Outline
There are thousands of snake species worldwide, and approximately 15% are considered dangerous to humans.1 The American Association of Poison Control Centers has recently reported that the United States averages approximately 6,000 snake bites every year, of which 2,000 are from venomous snakes.1, 2, 3, 4 However, the exact incidence of snake bites is unknown because most bites are not reported and receive no medical treatment. Most snake bites occur when humans and snakes are likely to be in the same environment, from April to October.5, 6 No more than 12 annual snake bite fatalities have been reported from 1960 to 1990.5
Educational Objectives
Few of the native snake species in the United States are venomous.1 The most common offenders are pit vipers, such as rattlesnakes (Fig. 1A), cottonmouths (Fig. 1B), and copperheads (Fig. 1C). Coral snakes also cause some bites. All states except Alaska, Maine, and Hawaii have native venomous snake species.1, 3 Snakes should never be handled because many have an inherent bite reflex that renders even decapitated snakes dangerous.1, 7 Even when snake bites occur, up to 25% do not result in envenomation.1, 8 Signs of envenomation include nausea/vomiting, paresthesias, pain, edema, erythema, ecchymosis, lymphangitis, bullae, altered taste, hypotension, delirium, respiratory distress, and/or coagulopathy.1These symptoms can manifest in minutes to hours and often result in a visit to medical professionals.
FIGURE 1.
Venomous snakes. A Rattlesnake. B Cottonmouth. C Copperhead.
Printed with permission from Public Health Image Library (PHIL). Centers for Disease Control and Prevention Web site. http://phil.cdc.gov/phil(image ID 8131, 8125, and 8130, respectively). Accessed July 19, 2010.
Treatment
Initial first aid principles include first moving the patient away from the snake, and then transporting the patient to the nearest medical facility. Immobilization of the affected extremity should be in a functional position. Electric shock, cryotherapy, incision/suction, and tourniquets are no longer recommended.1 Airway, breathing, and circulation are the first priorities, followed by a thorough history and physical examination. The bite site should be measured circumferentially above and below. These measurements should be repeated every 15 to 30 minutes, and the leading edge of swelling should be marked.1 Standard laboratory blood tests should be checked. Suspected snake bites should be observed for at least 8 to 12 hours.5, 9 Antivenin such as antivenin Crotalidae polyvalent or Crotalidae polyvalent immune Fab antivenom should be administered as indicated. All wounds should be cleaned and properly dressed. Tetanus immunization should be updated. Numerous regional poison control centers are available for assistance through nationally available 24-hour call centers.6
Complications
Care for snake bites can be complicated by problems with local wound management, lacerated deep structures, or rarely, compartment syndrome (Fig. 2). All wounds should be cleaned and dressed. Necrotic tissue at times requires debridement. Infections at the bite site are not common, and antibiotics should be used only when there are signs of local infection. Bites can damage deep structures, such as nerves, vessels, and tendons, which necessitates surgical intervention. Compartment syndrome can be difficult to diagnose because the reaction to the venom can mimic signs of compartment syndrome. Often, compartment pressures help in making the diagnosis. Some physicians recommend elevation of extremity and administration of Crotalidae polyvalent immune Fab antivenom before any surgical intervention.1, 10 Fasciotomies are not the standard of care for all snake bites, but they are performed when indicated. There is a lack of evidence-based literature on the role of antivenin and the need for fasciotomies.
FIGURE 2.
Patient with compartment syndrome of upper extremity, just before fasciotomies were performed. A, B The fasciotomy surgical sites are marked and the ecchymosis and swelling are noted. C The puncture wounds from the bite are seen.
Courtesy of Dr. John Elfar, University of Rochester Orthopaedics.
Snake bites are common and can affect the extremities. These often do not result in a hand surgery specialist consultation, and there is a resulting lack of literature on the topic. A basic understanding of the etiology, treatment recommendations, and complications of such bites can improve the effectiveness of patient care.
References
- . Bites of venomous snakes. N Engl J Med. 2002;347:347–356
- 2000 annual report of the American Association of Poison Control Centers Toxic Exposure Surveillance System. Am J Emerg Med. 2001;19:337–395
- 1999 annual report of the American Association of Poison Control Centers Toxic Exposure Surveillance System. Am J Emerg Med. 2000;18:517–574
- . Incidence of treated snakebites in the United States. Public Health Rep. 1966;81:269–276
- Comparison of a new ovine antigen binding fragment (Fab) antivenin for United States Crotalidae with the commercial antivenin for protection against venom-induced lethality in mice. Am J Trop Med Hyg. 1995;53:507–510
- . Venomous snakebites in the United States: management review and update. Am Fam Physician.2002;65:1367–1374
- . Venomous snakebites (Current concepts in diagnosis, treatment, and management). Emerg Med Clin North Am. 1992;10:249–267
- . Envenomation by the Eastern coral snake (Micrurus fulvius fulvius) (A study of 39 victims).JAMA. 1987;258:1615–1618
- . Envenomations. Crit Care Clin. 1999;15:353–386ix
- . The effect of antivenin on intramuscular pressure elevations induced by rattlesnake venom. Toxicon. 1985;23:677–680
No benefits in any form have been received or will be received related directly or indirectly to the subject of this article.
PII: S0363-5023(10)00789-6
doi:10.1016/j.jhsa.2010.07.005
© 2010 Published by Elsevier Inc.
