02-15-2009, 07:10 PM
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 Anaphylaxis - A severe allergic reaction that is rapid in onset and may cause death
Anaphylaxis Overview Quote: Definition
Quote: Anaphylaxis is a severe, potentially life-threatening allergic reaction. It can occur within seconds or minutes of exposure to something you're allergic to, such as the venom from a bee sting or a peanut.
The flood of chemicals released by your immune system during anaphylaxis can cause you to go into shock; your blood pressure drops suddenly and your airways narrow, blocking normal breathing. Signs and symptoms of anaphylaxis include a rapid, weak pulse, skin rash, and nausea and vomiting. Common triggers of anaphylaxis include certain foods, some medications, insect venom and latex.
Anaphylaxis requires an immediate trip to the emergency room and an injection of epinephrine. If anaphylaxis isn't treated right away, it can lead to unconsciousness or even death. | | Quote: Pathophysiology
Quote: Rapid onset of increased secretion from mucous membranes, increased bronchial smooth muscle tone, decreased vascular smooth muscle tone, and increased capillary permeability occur after exposure to an inciting substance. These effects are produced by the release of mediators, which include histamine, leukotriene C4, prostaglandin D2, and tryptase.
In the classic form, mediator release occurs when the antigen (allergen) binds to antigen-specific immunoglobulin E (IgE) attached to previously sensitized basophils and mast cells. The mediators are released almost immediately when the antigen binds. In an anaphylactoid reaction, exposure to an inciting substance causes direct release of mediators, a process that is not mediated by IgE. Increased mucous secretion and increased bronchial smooth muscle tone, as well as airway edema, contribute to the respiratory symptoms observed in anaphylaxis. Cardiovascular effects result from decreased vascular tone and capillary leakage. Histamine release in skin causes urticarial skin lesions.
The most common inciting agents in anaphylaxis are parenteral antibiotics (especially penicillins), IV contrast materials, Hymenoptera stings, and certain foods (most notably, peanuts). Oral medications and many other types of exposures also have been implicated. Anaphylaxis also may be idiopathic. | | Quote: Symptoms
Quote: An anaphylactic reaction is most likely to occur in susceptible people who've been stung by an insect, eaten something they're allergic to, or taken a medication that they are sensitive to. Even if you've only had a mild allergic reaction in the past, you still may be at risk of anaphylaxis.
Anaphylaxis symptoms usually occur within minutes of exposure to an allergen. In rare cases, anaphylaxis occurs more than half an hour after exposure. | Quote: Anaphylaxis symptoms include:
Quote: • Skin reactions including hives and itching, flushed or pale skin (almost always present with anaphylaxis)
• Constriction of the airways and a swollen tongue or throat, which can cause wheezing and trouble breathing
• A weak and rapid pulse
• Nausea, vomiting or diarrhea
• Dizziness or fainting | | |
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