Wilderness and Rescue Medicine 7th Edition Jeffrey Isaac, PA-C and David E. Johnson, MD

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Section III: Critical System Problems and Treatment

Chapter 8 Review: Allergy and Anaphylaxis

• Allergy and anaphylaxis are mediated by histamine, a chemical causing vasodilation and lower airway constriction. • Vasodilation results in fluid shift and soft tissue swelling capable of causing shock and respiratory failure. • The Wilderness Protocol for anaphylaxis calls for 0.3–0.5 mg of epinephrine by intramuscular injec- tion, 25–50 mg of diphenhydramine orally, and 40–60 mg of prednisone orally. • Epinephrine reverses the effects of histamine, diphenhydramine blocks the effects of histamine, and prednisone reduces the immune and inflammatory response. • Following treatment, evacuation for medical follow-up is ideal. In high-risk and remote settings, continued monitoring and use of diphenhydramine, and prednisone for several days may be indicated.