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(Circulation. 2005;112:IV-143 – IV-145.)
© 2005 American Heart Association, Inc.

2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

Part 10.6: Anaphylaxis

An extract of the first 250 words of the full text is provided, because this article has no abstract.

	Introduction

 
Anaphylaxis is a severe, systemic allergic reaction characterized by multisystem involvement, including the skin, airway, vascular system, and gastrointestinal tract. Severe cases may result in complete obstruction of the airway, cardiovascular collapse, and death. The term classic anaphylaxis refers to hypersensitivity reactions mediated by the subclass of antibodies immunoglobulins IgE and IgG. Prior sensitization to an allergen has occurred, producing antigen-specific immunoglobulins. Subsequent reexposure to the allergen provokes the anaphylactic reaction. Many anaphylactic reactions, however, occur without a documented prior exposure.

Anaphylactoid or pseudoanaphylactic reactions display a similar clinical syndrome, but they are not immune-mediated. Treatment for the two conditions is similar.

	Pathophysiology

 
The inciting allergen binds to antigen-specific IgE that has accumulated on previously sensitized basophils and mast cells. These cells almost immediately release a series of mediators, including histamines, leukotrienes, prostaglandins, thromboxanes, and bradykinins. When released locally and systemically, these mediators cause increased mucous membrane secretions, increased capillary permeability and leak, and markedly reduced smooth muscle tone in blood vessels (vasodilation) and bronchioles.

	Etiology

 
Any antigen capable of activating IgE can be a trigger for anaphylaxis. In terms of etiology, researchers generally list the following categories of causes: pharmacologic agents, latex, stinging insects, and foods. In up to 5% of cases the antigenic agent cannot be identified.

Pharmacologic agents. Antibiotics (especially parenteral penicillins and other ß-lactams), aspirin and nonsteroidal anti-inflammatory drugs, and intravenous (IV) contrast agents are the most frequent medications associated with life-threatening anaphylaxis.

Latex. Much attention has focused on latex-induced anaphylaxis, but it is actually quite rare.^1,2 A . . . [Full Text of this Article]