Wilderness and Rescue Medicine 8th Edition

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Section III: Critical System Problems and Treatment

The greatest direct risk would be in giving epi- nephrine to a patient who is suffering a heart attack. Fortunately, the signs, symptoms, and mechanism are markedly different and unlikely to be confused with anaphylaxis. The most com- mon problem to be mistaken for anaphylaxis in the field is acute stress reaction following multiple wasp or bee stings. In any case, once you have initiated field treat- ment with epinephrine, evacuation for medi- cal follow-up is considered ideal. If the patient has recovered from the event, it need not be an emergency. However, a history of previous

hospitalization for anaphylaxis or failure to improve to normal after the first injection indi- cates a higher risk patient. In remote or dangerous circumstances where evacuation is not safe or practical, continued use of an antihistamine may be advisable for several days. Continuing the prednisone once a day may also help prevent biphasic reactions and is safe for treatment up to 5 days. One 10mg dose of dexamethasone should be effective for up to 3 days. Careful monitoring is crucial.

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 mg of epinephrine by intramuscular injection, followed by an antihistamine (10 mg of cetirizine or 25–50 mg of diphenhydramine orally), as well as the administration of an oral steroid ( 10 mg of dexamethasone or 40–60 mg of prednisone). • Epinephrine reverses the effects of histamine. Cetirizine or diphenhydramine will block the effects of histamine. Dexamethasone or prednisone will reduce 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.