Definition and pathophysiology-anaphylaxis

(Ann Emerg Med 2006;47:373)

• Severe, rapid onset (mins to hrs), potentially life-threatening systemic allergic response

• IgE-mediated mast cell degranulation with release of histamine, tryptase, and TNF

• Precipitates systemic reactions (bronchospasm, tissue swelling, fluid shifts, vasodilation)

• Common triggers: penicillins, cephalosporins, shellfish, nuts, insect stings, IV contrast (not truly an IgE-mediated mechanism, but clinically similar)