Chapter 22 - Evaluation of a patient with anaphylaxis

Abstract

Anaphylaxis is an acute, potentially life-threatening, systemic allergic reaction usually affecting multiple organ systems. The diagnosis of anaphylaxis is clinical and requires assessment of a variety of symptoms and signs. A thorough history detailing the reaction and events surrounding anaphylaxis is critical in diagnosis and treatment, and in determining the trigger with the goal of avoiding future reactions. Differential diagnosis of several conditions mimicking anaphylaxis must be considered. The most common triggers for anaphylaxis are food, drugs, and hymenoptera sting. In the United States, peanut, tree nuts, milk, egg, wheat, soy, fish, shellfish, and sesame are major causes of immunoglobulin E-mediated food reactions. More delayed hypersensitivity reactions to foods are observed in α-gal sensitivity. In adults, drugs and hymenoptera stings are more common causes of anaphylaxis than foods. In cases of idiopathic anaphylaxis, a clear trigger is not identified. Following appropriate diagnosis and treatment of acute anaphylaxis, referral to an allergist is an important next step to determine whether further workup with skin testing, laboratory assays, or graded challenges should be considered.