الفهرس 
Pathophysiology of allergy and anaphylaxisOnly 14 pages are availabe for public view
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Abstract
Anaphylaxis is an acute, potentially lethal, multisystem syndrome resulting from the sudden release of mast cell and basophil-derived mediators into the circulation . It most often results from immunologic reactions to foods, medications, and insect stings, although it can also be induced through non-immunologic mechanisms by any agent (e.g. latex) capable of producing a sudden, systemic degranulation of mast cells or basophils (Ebo et al., 2008).
The term ”anaphylaxis” has traditionally been reserved for IgE-dependent events, and the term ”anaphylactoid reaction” has been used to describe IgE-independent events, although the two reactions are often clinically indistinguishable (Gerber and Pichler, 2006).
Patients undergoing general anesthesia and surgery can experience complex physiologic changes. Recognition of an allergic reaction that occurs during anesthesia is potentially masked by hypotension produced during induction of anesthesia by Propofol or other induction agents, sympathectomy associated with spinal/epidural anesthesia, the inability of the anesthetized patient to communicate early symptoms such as itching, and coverage of the patient by surgical drapes that may obscure detection of cutaneous signs (Johansson et al., 2010).
The most common identifiable causes of perioperative anaphylaxis are neuromuscular-blocking agents (NMBAs), antibiotics, latex, hypnotic induction agents (primarily barbiturates), opioids, and colloids. However, there is a much longer list of agents that are implicated less regularly. In a significant number of cases, no specific trigger can be identified (Mertes et al., 2008).
The safest management approach for a patient with past anaphylaxis is the definitive identification and complete avoidance of the trigger. If this is not possible or evaluation does not reveal a specific culprit, then future management is based upon avoidance of high-risk agents and implementation of general precautions. For patients who require repeat anesthesia, general precautionary measures include optimal preoperative control of asthma, slow administration of antibiotics and other high-risk agents, and avoidance (when possible) of beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, and drugs that cause direct histamine release from mast cells/basophils (Mertes et al., 2011).