![]() ![]() Immune-mediated allergic reactions are classified, according to their mechanism, on the basis of the Gell and Coombs classification. Anaphylaxis generally occurs on reexposure to a specific antigen and requires the release of proinflammatory mediators, but it can also occur on first exposure, because there is cross-reactivity among many commercial products and drugs. Shock could also arise in severe anaphylactoid reaction that is clinically indistinguishable from anaphylaxis, but are not IgE-mediated and is seen in response to opiates, nonsteroidal anti-inflammatory drugs, and radiocontrast agents. Potentially any substance is able to cause anaphylaxis however, the most common causes of IgE-mediated anaphylaxis are insect stings, medications, latex, peanuts and tree nuts, shellfish and fish, milk, eggs, and wheat. Fatality from anaphylactic shock, though uncommon, may occur most commonly from cardiovascular collapse and airway obstruction if medical attention is delayed. It presents unheralded in otherwise healthy people and mandates prompt clinical diagnosis based on pattern recognition and probability, in the absence of any immediate confirmatory test.Īnaphylaxis is a medical emergency that requires immediate attention as respiratory distress and, in case of anaphylactic shock, vascular collapse may occur within minutes after exposure to the allergic substances. ![]() Anaphylaxis following exposure to a trigger presents in a dynamic continuum from mild to severe, gradual in onset to fulminant, and may involve multiple organ systems or cause isolated shock or wheeze. It represents the most catastrophic of the immediate-type generalized hypersensitivity reactions. Where nonimmunological mechanisms are involved, the WAO paper suggests that the term nonallergic anaphylaxis is used. ![]() In IgE-mediated allergic anaphylaxis there is a systemic release of mediators by mast cells and basophils. The World Allergy Organisation (WAO) has suggested that the term allergic anaphylaxis is used to describe immunological reactions involving IgE, IgG, or immune complexes. The term anaphylaxis literally meaning “against protection” was introduced by Richet and Portier in 1902. Prompt administration of epinephrine is critical for the success in the treatment of acute anaphylaxis. More severe symptoms include bronchial constriction, hypotension, vascular collapse associated with angioedema and urticaria, gastrointestinal distress, cardiovascular arrhythmias, and arrest. Anaphylaxis is a clinical diagnosis with a combinations of symptoms and signs that include weakness, dizziness, flushing, angioedema, urticaria of the skin, congestion, and sneezing. Positive feedback mechanisms amplify the reaction, although conversely reactions can self-limit. ![]() These cause vasodilatation, increased capillary permeability, and smooth muscle contraction, and attract new cells to the area. The pathophysiology involves activated mast cells and basophils releasing preformed, granule-associated mediators, and newly formed lipid mediators, as well as generating cytokines and chemokines. Anaphylaxis is an acute, systemic, IgE-mediated, and immediate hypersensitivity reaction caused by the release of mediators by mast cells and basophils after exposure to antigens. Anaphylactic shock is medical emergency characterized by circulatory collapse resulted from severe acute allergic reactions, namely anaphylaxis and anaphylactoid reaction. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |