Anaphylaxis

Basics

Description

  • An acute, widely distributed form of shock that occurs within minutes of exposure to antigen in a sensitized individual
  • The overall rate of anaphylaxis appears to be increasing, especially in children
  • An overall incidence rate of about 50–100 per 100,000 person-years is estimated from current data:
    • Fortunately, case fatality rates are low for patients who are treated promptly with epinephrine (0.1–0.3%)
  • Involves release of bioactive molecules such as histamine, leukotrienes, and prostaglandins from inflammatory cells:
    • Mediator release results in increased vascular permeability, vasodilation, smooth-muscle contractions, and increased epithelial secretion
    • Physiologically, this is manifested in a decrease in total peripheral resistance, venous return, and cardiac output, as well as intravascular volume depletion

Etiology

  • IgE mediated:
    • Foods (peanuts, tree nuts, shellfish, eggs, milk)
    • Medications (antibiotics particularly beta-lactams), NSAIDs, anesthetics
    • Latex
    • Vaccines
    • Monoclonal antibody therapeutics
  • Non-IgE mediated:
    • Iodine contrast media
    • Medications such as opioids and vancomycin
    • Physical Factors (exercise, cold, heat)
    • Substances that cause direct mast cell activation (alcohol, high-histamine foods, additives)

Pediatric Considerations

In children, foods are an important trigger for IgE-mediated anaphylaxis:

  • The most common foods to cause anaphylactic events are peanuts, tree nuts, fish, shellfish, milk, and egg, but any food can produce a reaction

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