Anaphylaxis is a life-threatening allergic reaction. It can be stimulated by several different allergens, normally from food, medications, insect venom, and latex. The authoritative treatment for anaphylaxis is adrenaline (epinephrine), and all patients at exposed risk for experiencing anaphylaxis are urged to carry self-injectable medication with them at all times. Side effects of epinephrine may include palpitations, tachycardia (an abnormally fast heartbeat), sweating, nausea and vomiting, and respiratory difficulty. Cardiac arrhythmias may follow administration of epinephrine. Patients should seek the advice of their physician on under what condition should this life-saving medication be used.
Click on the following links to learn about each individual allergens.
Food:http://www.anaphylaxis.com/page/food
Insects:http://www.anaphylaxis.com/page/stinging-insects
Medication:http://www.anaphylaxis.com/page/medications
Latex:http://www.anaphylaxis.com/page/latex
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1) Antigen-presenting cell internalizes antigen.
2) The APC processes the internalized antigen.
3) The APC presents the processed peptide to CD4+ T lymphocytes via MHC II.
4) After the peptide is presented, the T cell differentiates into TH2 lymphocytes and produces IL-4, IL-5, IL-9, and IL-13.
5) IL-4 and IL-13 cause B cell immunoglobulin isotype switching to IgE.
6) The circulating IgE binds to the IgE receptors on mast cells.
7) Antigen similar to the original antigen cross-links the mast cell surface-bound IgE, resulting in cellular degranulation. Degranulation releases histamine, tryptase, and other mediators that produce the symptoms of anaphylaxis (Anaesthesia UK, 2005).
Below is a pictorial illustration of what was stated as above
http://www.bio.davidson.edu/courses/immunology/Students/spring2006/Witcher/Anaphylaxis.html
Thinking that the above is too hard to understand?
We’ve got a simplified explanation over here.
Basically an anaphylaxis has an anaphylactic reaction that is caused by sudden release of chemical substances such as histamine from cells in the blood and tissues that are stored. And this release is trigged by the allergic antibody (IgE) and the allergen. The mechanism is so sensitive that when the release of the allergen is very minimal, it can cause a reaction. The released chemicals will then act on blood vessels causing the swelling.
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Other kinds of anaphylaxis discovered include Idiopathic Anaphylaxis and Exercise-induced Anaphylaxis. However, they are not understood as fully as other forms of anaphylaxis.
Idiopathic Anaphylaxis
It is anaphylaxis caused by an unknown trigger. However, doctors can and should make careful analysis of the events and conditions surrounding the attack so as to discover any possible allergens that have previously been unknown.
The main symptoms of idiopathic anaphylaxis includes hives, difficulty in breathing or swallowing and swelling of the throat, lips, tongue, or around the eyes. Other common symptoms of anaphylaxis may also occur.
Treating an emergency case of idiopathic anaphylaxis is the same as treating other forms of anaphylaxis with the main therapy being epinephrine.
Individuals who experience idiopathic anaphylaxis may be treated prophylactically (preventively or protectively) with corticosteroids, beta-agonists, and/or antihistamines. However, these therapies require individuals’ responsibility.
Exercise-Induced Anaphylaxis
Exercise-induced anaphylaxis is a form of physical allergy. Although the mechanism by which this reaction occurs has yet to be clearly identified, it has been found that some medications (such as aspirin or NSAIDS) or food before exercise increase the probability of experiencing exercise-induced anaphylaxis.
Individuals at risk for experiencing exercise-induced anaphylaxis are those with a history of personal or family atopy which is the increased tendency seen in some individuals to produce IgE antibodies to innocuous substances.
Initial symptoms of exercise-induced anaphylaxis includes fatigue, diffuse warmth, Pruritus (localized or generalized itching due to irritation of sensory nerve endings from organic or psychogenic causes), Erythema (abnormal redness of the skin due to capillary congestion, as in inflammation), Urticaria(a transient condition of the skin, usually caused by an allergic reaction, characterized by pale or reddened irregular, elevated patches and severe itching; hives.)
Later onset symptoms of exercise-induced anaphylaxis include gastrointestinal symptoms, laryngeal edema and vascular collapse.
Treating an emergency case of exercise-induced anaphylaxis is the same as treating other forms of anaphylaxis with the main therapy being epinephrine. Prophylactic (preventative or protective) medications like corticosteroids, beta-agonists, and/or antihistamines have not been shown to be useful for exercise-induced anaphylaxis.
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Please watch the video below. It is an animation that explains the mechanism of anaphylaxis.
Reaction of Anaphylaxis 
http://www.allergyfacts.org.au/images/boy-2.jpg
(Severe)http://www.guysandstthomas.nhs.uk/resources/Image/P/paediactricallergy/PaedAllergy_DrugAnaphylaxisInChild.jpg
http://www.umm.edu/graphics/images/en/19320.jpg
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Management of Anaphylaxis
Treatment and Prevention
Adrenaline (epinephrine) is the main form of treatment. It should be administered immediately by the intramuscular route. After which, IV or IM hydrocortisone and an anti-histamine (chlorphenaramine or diphenhydramine) should be given. Other therapy like neubulised beta2-agonist, oxygen and IV fluids should also be included as necessary.
If initial reaction is mild without cardiorespiratory problem, it is sufficient to give hydrocortisone (IV or IM) and diphenhydramine (slow IV or IM). If features of hypotension or respiratory obstruction occurs, IM adrenaline should be administered immediately with re-injection of every 5 to 15 minutes till the anaphylaxis or symptoms of toxicity subsided. IV adrenaline cannot be given outside of hospital as it can result in cardiac toxicity if misused.
For anyone with an allergy reaction, call for medical help to get to the closest emergency room. The sooner the reaction is treated, the less severe it is likely to become.
If medication is taken and individual feels better, do not skip further check ups. It is advisable to visit the hospital again to make sure allergy reaction is under control.
Once there is an anaphylactic reaction, visit an allergist to get a proper diagnosis. The allergist will take the medical history of patient and conduct other tests, if needed, to determine the exact cause of the reaction.
The allergist can provide information about avoiding the allergen as well as a treatment plan. Avoiding the allergen(s) is the main way to remain safe, but requires good knowledge of precautions.
In some cases, the allergist may suggest specific treatments, such as allergy shots or immunotherapy, a treatment designed to produce immunity to a disease or enhance the resistance of the immune system to an active disease process to eliminate the risk of anaphylaxis completely from insect stings, or steps that make it possible to be treated with certain medications according to the specific allergen.
The allergist may also prescribe auto-injectable epinephrine. Make sure one understands how and when to use it. Always refill the prescription upon expiration. This medication should be carried around at all times.
The allergist may also request one to wear special jewelry. For example MedicAlert bracelet or necklace, which signify that one have severe allergy problem. This ID can provide physicians and others with important information about one's medical condition.
If one have had an anaphylactic reaction, inform family, healthcare workers, employers and school staff about the allergy so they can watch for symptoms, help avoid the allergens and develop a treatment plan.
Optimal management of anaphylaxis saves lives. An affected or at-risk person must be aware of possible triggers and early symptoms. If one is prone to these reactions, they must be familiar with the use of emergency anaphylaxis treatment kits and always have it with them. Emergency measures and prevention are central to management. Anaphylaxis are best treated by avoidance measures, which will be summarised below.
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Basic Avoidance Measures for Anaphylaxis
Drugs/Medications
- Advise all health care personnel of your allergies.
- Ask your doctor whether the prescribed medication contains the drug(s) you are allergic to.
- Take all drugs by mouth if possible.
Insect Stings
- Avoid areas such as outdoor garbage, barbecues, and insect nests.
- Avoid bright clothing, perfume, hair spray or lotion that might attract insects.
- Wear long sleeved clothing, long trousers, and shoes while outdoors
Food
- Carefully read all labels.
- Ask what the ingredients are when eating out.
- Avoid foods that may cross react such as bananas, kiwi fruit, and avocado.
Latex
- Avoid all Latex products.
- Ask if your hospital has Latex safety issues if you need to be hospitalized.
- Patient with a history of anaphylaxis should be instructed on how to initiate treatment for future episodes using pre-loaded epinephrine syringes.
- Two strengths are available: 0.3 mL of 1:1,000 epinephrine for adults, and 0.3 mL of 1:2,000 for children.
- Family members and care-givers of young children should be trained to inject epinephrine.
- Patient must be told to seek immediate professional help regardless of initial response to self-treatment.
- They should avoid taking beta blockers, angiotensin-converting enzyme (ACE) inhibitors, angiotensin-II receptor blockers, and monoamine oxidase inhibitors, as those drugs may interfere with the treatment of future anaphylactic or with the endogenous compensatory responses to hypotension.
- Patient should be advised to wear or carry a medical alert bracelet, necklace, or keychain to notify emergency personnel of the possibility of anaphylaxis.
References:
- The Anaphylaxis Campaign.2008. Basic Facts [online]. Available from:http://www.anaphylaxis.org.uk/information/basic-facts.aspx [Assessed 4th Feb 2010]
- MedicineNet. 2010. Anaphylaxis(Severe Allergic Reaction)[online]. Available from: http://www.medicinenet.com/script/main/art.asp?articlekey=12953&page=6#8howdo [Assessed 4th Feb 2010]
- American Academy of Family Physicians. 2003. A Practical Guide to Anaphylaxis[online]. Available from: http://www.aafp.org/afp/2003/1001/p1325.html [Assessed 4th Feb 2010]
- American Academy of Allergy Asthma & Immunology.2009. Tips to Remember: Anaphylaxis. [online]. Available from: http://www.aaaai.org/patients/publicedmat/tips/whatisanaphylaxis.[Assessed 4th Feb 2010]
- DEY. 2001. Anaphylaxis.com:About Anaphylaxis [online]. Available from: http://www.anaphylaxis.com/ .[Assessed 7th Feb 2010]
- National University Hospital.2004.Paediatric Shared Care Programme[Online]. Available from: http://www.nuh.com.sg/_kids/files/medicalEducation/sharedCaredProgramme/bulletin_36.pdf [Assessed 7th Feb 2010]
