Wilderness and Rescue Medicine 8th Edition

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Wilderness and Rescue Medicine

General Principles

Local Reaction

2

Signs and Symptoms: • Rash, swelling, itching

limited to site of exposure

Treatment: • Dilute and remove foreign substance • Systemic antihistamines and topical steroids

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Low Risk

High Risk

© 2018 WMA

A systemic response to an allergen, by contrast, can produce generalized itching and hives all over the body surface. The patient may give a history of a specific allergy, or the history may be completely unrevealing. As long as there is no swelling, no facial involvement, no respiratory distress, and no signs of vascular shock, we call this a mild allergic reaction. It usually resolves on its own or responds well to treatment with oral antihistamines (e.g. diphenhydramine/Benadryl). Often, the patient will give a history of similar symptoms and suc- cessful treatment with oral medications. This is reassuring for field treatment, but still requires careful monitoring because any reaction can be more severe than expected.

Hives tend to appear and disappear from vari- ous areas of the skin surface, sometimes within minutes. Anaphylaxis Anaphylaxis is a severe form of systemic aller- gy that results in critical system problems. Widespread vasodilation and fluid shift into the interstitial space can cause vascular and volume shock, upper airway swelling, vomiting, and diar- rhea. Lower airway constriction results in wheez- ing and respiratory distress. The patient can die within a matter of minutes. Symptoms can progress quickly from an initial complaint of itchy skin and hives with a scratchy or constricted feeling in the throat. Patients often report feeling a sense of impending doom. As the reaction becomes more severe, signs and symp- toms including wheezing, stridor, facial swelling, nausea, vomiting, or diarrhea may develop. There will be weakness and mental status changes with the onset of vascular and volume shock.

Mild Allergic Reaction

Signs and Symptoms: • Truncal hives and itching • Normal mental status • No facial swelling • No tight or scratchy throat • No respiratory distress • No signs of shock

Low Risk

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High Risk