Allergic and Immunologic Emergencies
A. Definition. Anaphylaxis is an immediate, generalized, life-threatening reaction resulting from the release of bioactive substances from mast cells and basophils. Anaphylaxis can occur in more than one time period. The so-called biphasic anaphylaxis is defined as a recurrence of symptoms that develops following the “resolution” of the initial anaphylactic reaction. It can occur in up to 20% of anaphylactic reactions and typically occurs within 8 h after resolution of the initial symptoms. Recurrences up to 72 h later can occur.