What is Pressure Immobilization?
- Pressure immobilization is a term used to describe the application of a pressure device and immobilization to an affected extremity (arm or leg) after a bite in order to delay the systemic absorption of venom. This technique slows the lymphatic flow, and thus decreases the body's uptake of venom. This first aid temporizing measure is implemented until definitive care and management can be provided at the nearest health care facility.
- The idea of pressure immobilization was initially introduced in Australia in the 1970's to prevent the dissemination of the neurotoxin released by snakes from the Elapidae family. This neurotoxin, which does not typically cause localized tissue death (necrosis), can lead to generalized muscle weakness and ultimately respiratory arrest.
- In 2010, the American Heart Association and the American Red Cross published their latest first aid guidelines which recommend the use of properly performed pressure immobilization following snake envenomations. Within the toxicology community, however, these general guidelines have been controversial for certain snakebites.
- Toxicologists argue that in the United States, many snakebite envenomations are from Crotalidae, such as rattlesnakes, copperheads and cottonmouths, whose bites predominantly cause local tissue necrosis. Toxicologists believe that by applying pressure immobilization after Crotalidae snakebites, localized tissue destruction is increased by entrapping and sequestering the venom. Consequently, most toxicologists currently do not recommend the use of pressure immobilization for North American Crotalidae envenomations.
- Pressure immobilization is never indicated in nonsnake envenomation. Anytime pressure immobilization is applied the patient needs to be transported to a health care facility.
Pressure Immobilization Technique
Proper application of a pressure immobilization device is critical to achieving the desired results. Applying the pressure immobilization bandage properly requires wrapping the entire affected extremity, and generating pressures between 40-70 mmHg in the upper extremity and 55-70 mmHg in the lower extremity. A practical estimation to achieve these pressure ranges is applying the bandage snug and comfortably tight, while still allowing a finger to be slipped under it. Applying the pressure immobilization bandage too loose renders it ineffective, while applying it too tight can create worsening tissue damage. Studies have shown that once this technique is learned, unfortunately there is poor retention of the skill and inappropriate application is common. After application of the pressure immobilization bandage is complete, the extremity should then be splinted and immobilized. A sling can be used to immobilize the upper extremity. The individual should then be transported to the nearest health care facility. Proper removal of the bandage should occur at the health care facility.
Medically reviewed by Avrom Simon, MD; Board Certified Preventative Medicine with Subspecialty in Occupational Medicine
American College of Medical Toxicology, American Academy of Clinical Toxicology, American Association of Poison Control Centers, et al. Pressure immobilization after North American Crotalinae snake envenomation. J Med Toxicol. 2011; 7:322.