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

A previous history of anaphylaxis is not neces- sary to make the diagnosis. A significant percent- age of patients presenting with anaphylaxis will have no known history of allergy. In the remote setting, early and aggressive treatment for evolv-

pressed firmly against the skin. In the United States, these devices are available only by pre- scription. Patients known to have severe aller- gies often carry one. Many other countries like Canada and Mexico allow autoinjector sales with- out prescription.

ing anaphylaxis is always warranted. Treatment of Anaphylaxis

General Principles

Anaphylaxis Treatment Epinephrine: • 0.01 mg/kg up to 0.5 mg by intramuscular injection. Average adult dose is 0.3 – 0.5 mg. • Repeat as soon as 5 minutes if needed • Action: bronchodilation, vasoconstriction, stabilizes mast cells WILDERNESS PROTOCOL Antihistamine • Action: blocks histamine at receptor sites • eg: diphenhydramine 1 mg/kg up to 50 mg by mouth Prednisone: • 1 mg/kg up to 60 mg by mouth • Action: anti-inflammatory, may help prevent biphasic reaction Anaphylaxis Treatment Smaller People (< 25 kg): • Epinephrine dose is 0.01 mg/kg. • Note: Autoinjectors are available in 0.1, 0.15, 0.3, and 0.5 mg versions. • Prednisone dose is 1 mg/kg. • Antihistamine eg: diphenhydramine dose is 1 mg/kg. WILDERNESS PROTOCOL

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BLS and PROP is appropriate, but not definitive. Specific treatment with epinephrine is required to immediately reverse the systemic response. The Wilderness Protocol for anaphylaxis adds the use of diphenhydramine and prednisone which may help prevent the reoccurrence of the problem. The recognition of anaphylaxis and the use of these medications are important skills for the wilder- ness medical practitioner. Epinephrine is a potent vasoconstrictor and bronchodilator that also helps to stabilize the activated mast cells, reducing the release of his- tamine and other mediators. It is most effective when injected into the muscle of the lateral aspect of the thigh at a dose of 0.3 to 0.5 mg. The patient’s symptoms usually improve within 90 seconds. Repeat doses may be necessary if symptoms do not improve or if a rebound (biphasic) reaction occurs.

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General Principles

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General Principles

Anaphylaxis Treatment

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Evacuation: • Transport with additional epi on hand • Can be non-emergent if treatment was successful and vital signs return to normal • Continue diphenhydramine 25 mg every 6 hours, or other antihistamine as directed, if evacuation is delayed • Continue prednisone once per day up to 5 days if evacuation is delayed WILDERNESS PROTOCOL

Hives on the abdomen of a patient with anaphy- laxis, prior to the administration of epinephrine. Epinephrine is supplied as a liquid specifically for the treatment of anaphylaxis in the form of a pre-loaded autoinjector such as an EpiPen that automatically injects the specified dose when

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In the backcountry setting, it is advisable to carry at least three doses of epinephrine to cover biphasic reactions during evaluation and