Background
The vast majority of venomous snake bites treated at health care facilities in the United States each year involve non-neurotoxic Crotalinae species.Citation1 Large case series reveal the major clinical effect associated with these envenomations to be local tissue injury. Extremity swelling and dermonecrosis are common, with compartment syndrome an infrequent but potentially limb-threatening effect of envenomation.Citation2,Citation3,Citation4,Citation5 Life-threatening systemic toxicity and death are rare.
Historically, many first-aid measures have been employed in the treatment of snake bites, but none has been shown to improve patient outcome. Pressure immobilization is a technique routinely employed in the pre-hospital management of neurotoxic snake species in Australia. First described by Sutherland and colleagues in the 1970s, pressure immobilization involves wrapping the entire extremity with a bandage and then immobilizing the extremity with a splint.Citation6 The bandage should generate a pressure between 40–70 mm Hg in the upper extremity and 55–70 mmHg in the lower extremity in order to effectively delay systemic absorption of venom.Citation7
Several animal studies have demonstrated delayed systemic absorption of venom with pressure immobilization.Citation6,Citation7,Citation8 However, studies have also revealed that pressure immobilization bandages are commonly applied incorrectly, even in a simulated setting following provider instructions and training.Citation9,Citation10,Citation11,Citation12 Although the more common error is to apply the bandage too loosely, the bandage may function as a tourniquet when applied too tightly, causing limb ischemia, and may also increase systemic absorption of venom.Citation7
Animal models of North American Crotalinae envenomation demonstrate delayed systemic absorption of venom and delayed mortality following application of pressure immobilization bandages.Citation13,Citation14,Citation15 However, the local effects of sequestering cytotoxic venom in the extremity are less clear. In a swine model of pressure immobilization following C atrox lower extremity envenomation, intracompartmental pressure increased significantly compared to controls, from a non-surgical range to levels that would prompt fasciotomy.Citation13
Position
Given that the primary toxic effect of envenomation is local tissue injury, mortality is not an ideal outcome measure to extrapolate to human crotaline envenomation. Available evidence fails to establish the efficacy of pressure immobilization in humans, but indicates the possibility of serious adverse events arising from its use. The use of pressure immobilization for the pre-hospital treatment of North American Crotalinae envenomation is not recommended.
Acknowledgements
The organizations acknowledge the efforts of Michael Levine, MD, and Michelle Ruha, MD in creating this position statement.
Declaration of interest
The societies endorsing this position statement have no conflicts to report. This work has been endorsed by American College of Medical Toxicology, American Academy of Clinical Toxicology, American Association of Poison Control Centers, European Association of Poison Control Centres and Clinical Toxicologists, International Society of Toxinology and Asia Pacific Association of Medical Toxicology
References
- Bronstein AC, Spyker DA, Cantilena LR Jr, Green JL, Rumack BH, Giffin SL. 2009 Annual report of the American Association of Poison Control Centers’ National Poison Data System (NPDS): 27th Annual Report. Clin Toxicol 2010; 48:979–1178.
- Corneille MG, Larson S, Stewart RM, Dent D, Myers JG, Lopez PP, McFarland MJ, Cohn SM. A large single-center experience with treatment of patients with crotalid envenomations: outcomes with and evolution of antivenin therapy. Am J Surg 2006; 192(6):848–852.
- Spiller HA, Bosse GM. Prospective study of morbidity associated with snakebite envenomation. J Toxicol Clin Toxicol 2003; 41(2): 125–130.
- Tanen D, Ruha AM, Graeme K, Curry S. Epidemiology and hospital course of rattlesnake envenomations cared for at a tertiary referral center in central Arizona. Acad Emerg Med 2001; 8(2):177–182.
- Thorson A, Lavonas EJ, Rouse AM, Kerns WP. Copperhead envenomations in the Carolinas. J Toxicol Clin Toxicol 2003; 41(1): 29–35.
- Sutherland SK, Coulter AR, Harris RD. Rationalisation of first-aid measures for elapid snakebite. Lancet 1979; 27:183–185.
- Howarth DM, Southee AE, Whyte IM. Lymphatic flow rates and first-aid in simulated peripheral snake or spider envenomation. Med J Aust 1994; 161:695–700.
- German BT, Hack JB, Brewer K, Meggs WJ. Pressure-immobilization bandages delay toxicity in a porcine model of Eastern coral snake (Micrurus fulvius fulvius) envenomation. Ann Emerg Med 2005; 45: 603–608.
- Canale E, Isbister GK, Currie BJ. Investigating pressure bandaging for snakebite in a simulated setting: bandage type, training, and the effect of transport. Emerg Med Australas 2009; 21:184–190.
- Currie BJ, Canale E, Isbister GK. Effectiveness of pressure-immobilization first aid for snakebite requires further study. Emerg Med Australas 2008; 20:267–270.
- Norris RL, Ngo J, Nolan K, Hooker G. Physicians and lay people are unable to apply pressure immobilization properly in a simulated snakebite scenario. Wilderness Environ Med 2005; 16:16–21.
- Simpson ID, Tanwar PD, Andrade C, Kochar DK, Norris RL. The Ebbinghaus retention curve: training does not increase the ability to apply pressure immobilization in simulated snake bite – implications for snake bite first aid in the developing world. Trans R Soc Trop Med Hyg 2008; 102(5):451–459.
- Bush SP, Green SM, Laack TA, Hayes WK, Cardwell MD, Tanen DA. Pressure immobilization delays mortality and increases intracompartmental pressure after artificial intramuscular rattlesnake envenomation in a porcine model. Ann Emerg Med 2004; 44:599–604.
- Meggs WJ, Courtney C, O'Rourke D, Brewer KL. Pilot studies of pressure-immobilization bandages for rattlesnake envenomations. Clin Toxicol 2010; 48:61–63.
- Sutherland SK, Coulter AR. Early management of bites by the Eastern diamondback rattlesnake (Crotalus adamanteus): studies in monkeys (Macaca fascicularis). Am J Trop Med Hyg 1981; 30: 497–200.