Definition Anaphylaxis : rapid, generalized immunologically mediated events involving an antigen-specific IgE-mediated mechanism that occur after exposure to foreign substances in previously sensitized persons Anaphylactoid reaction : not mediated by way of the IgE antibody and prior exposure is not necessary
The incidence of anaphylaxis in GA is about 1:5000 to 1: 20000 and with a mortality rate of up to 6%
Mechanism : 1. Specific IgE cross-linked by allergen (drug)
2. Complement activation by specific IgG or IgM binding to antigen (drug)
3. Direct complement activation by way of the alternate pathway
4. Direct activation of mast cells or basophils
CAUSES OF ANAPHYLAXIS AND ANAPHYLACTOID REACTIONS DURING ANESTHESIA Causes Rate of Reaction (%) Muscle relaxants 61.6 Latex 16.6 Antibiotics 8.3 Hypnotics 5.1 Colloids 3.1 Opioids 2.7 Other (aprotinin, ethylene oxide, local anesthetics) 2.6 Data from French survey by Perioperative Anaphylactoid Reactions Study Group; 1648 patients, July 1994 to December 1996.
degranulated mast cells are increased in the adventitia of the coronary artery segments with ruptured plaque that are responsible for MI, suggesting histamine and other vasoactive substances released from the adventitial mast cells may locally provoke coronary artery spasm