New York, NY—Intramuscular epinephrine is the primary treatment for anaphylaxis, and guidelines state that the shot should be administered before adjunctive treatments such as antihistamines, corticosteroids, and inhaled beta-agonists.

That all might seem straightforward, but the situation can be much more complicated in the "great outdoors".

"For outdoor schools and organizations, selecting a method to administer epinephrine in the field is based on considerations of cost, safety, and first responder training, as well as federal guidelines and state-specific laws," according to the Wilderness Medical Society, which recently convened a panel to review the literature and develop evidence-based clinical practice guidelines on the treatment of anaphylaxis, with an emphasis on a field-based perspective.

The group's review also included literature regarding the definition, epidemiology, clinical manifestations, and prevention of anaphylaxis. One impetus, according to New York Presbyterian-Weill Cornell Medicine—led authors and colleagues, is the increasing prevalence of food allergies in the United States, which has the potential to increase the incidence of anaphylaxis

The goal of the guidelines published in Wilderness & Environmental Medicine is to help outdoor-based programs, organizations, and individuals concerned with wilderness or field conditions to develop policies and procedures on anaphylaxis tailored to their missions and operating environments.

The authors pointed out that common triggers for anaphylaxis are foods (including nuts, milk, fish, shellfish, eggs, and certain fruits); medications (including certain antibiotics and non-steroidal anti-inflammatory drugs); and insect stings (particularly wasp and bee stings).

"Since 2010, to help increase the availability of life-saving treatment, WMS has supported the position that nonmedical professionals whose duties include providing first aid or emergency medical care in the field should also be trained to administer epinephrine for anaphylaxis," explained lead author Flavio G. Gaudio, MD, of the Department of Emergency Medicine at New York Presbyterian-Weill Cornell Medicine. "Examples of such professionals include expedition leaders, outdoor instructors or guides, park rangers, and camp directors."

The guidelines include new information pulled from databases of the National Outdoor Leadership School (NOLS) and Outward Bound-USA, which are two well-established schools leading wilderness courses and expeditions. The data indicated that anaphylaxis occurred in 0.01% to 0.03% of participants, respectively.

While the authors conceded that the overall incidence of anaphylaxis is low, they emphasized that cases have burgeoned in recent decades—a 12-fold increase in anaphylaxis and a threefold increase in nonanaphylactic allergic reactions in the NOLS database.

Most causes of anaphylaxis were food allergies and insect stings, but more than 20% were first-time reactions in people with no known allergy history.

The study's findings include that:

• Both autoinjectors and manual syringes have been safely used to administer epinephrine in field conditions.
• OTC metered-dose inhalers of epinephrine often are not practical or effective treatment for anaphylaxis.
• Antihistamines, corticosteroids, and inhaled beta-agonists are supplemental anaphylaxis treatments that should not delay epinephrine administration. Antihistamines might help mitigate the overall severity of anaphylaxis, and nonsedating formulations are recommended for the field.
• The benefit of corticosteroids is not completely proven, but empiric use is reasonable given the potential for benefit paired with a generally low side-effect profile.
• In refractory anaphylaxis cases, epinephrine may be given every 5 to 15 minutes along with the secondary treatments of antihistamines and corticosteroids, as well as inhaled beta-agonists for patients with bronchospasm.
• The severity of the initial reaction and risk factors for a biphasic reaction determine the necessary length of observation after anaphylaxis treatment.
• An epinephrine prescription should be provided to patients before discharge from a medical center, and they should be advised to follow up for allergy testing and consideration of immunotherapy.
• Patients with prior anaphylactic reactions to Hymenoptera venom (for example, from wasps, bees, and fire ants) and peanut sensitivity should consider desensitization.

The guidelines also provided information on topics unique to nonoptimal settings, including the potency of epinephrine when stored and transported in field conditions and subject to temperature fluctuations; the extraction of additional epinephrine from autoinjectors after medication discharge (in extreme emergencies or life-saving circumstances, when no other source is available); and the use of expired epinephrine.

"The guidelines do not provide simple, how-to algorithms that apply to all settings, especially considering different patient characteristics, different training and resources available to each first responder or practitioner, and different topography or field conditions," Dr. Gaudio pointed out. "However, given the breadth and scope of the guidelines, outdoor-based programs and organizations should find some information and recommendations useful to their particular operational needs. Finally, organizations that plan to carry epinephrine into the field must consult and follow both the relevant federal guidelines as well as state-specific laws."

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