ALTERNATIVE NAMES: Anaphylactic reaction; Anaphylactic shock; Shock – anaphylactic
Anaphylaxis is an acute multi-system severe type I hypersensitivity reaction. The term comes from the Greek words ava ana (against) and phylaxis (protection).It is a life-threatening type of allergic reaction and 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, a skin rash, and nausea and vomiting. Common triggers of anaphylaxis include certain foods, some medications, insect venom and latex.
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Due in part to the variety of definitions, between 1% and 15% of the population of the United States can be considered “at risk” for having an anaphylactic reaction if they are exposed to one or more allergens. Of those people who actually experience anaphylaxis, up to 1% may die as a result. Anaphylaxis results in approximately 1,500 deaths per year in the U.S. In England, mortality rates for anaphylaxis have been reported as up to 0.05 per 100,000 population, or around 10-20 a year. Anaphylactic reactions requiring hospital treatment appear to be increasing, with authorities in England reporting a threefold increase between 1994 and 2004.
Based on the pathophysiology, anaphylaxis can be divided into “true anaphylaxis” and “pseudo-anaphylaxis” or “anaphylactoid reaction.” The symptoms, treatment, and risk of death are the same; however, “true” anaphylaxis is caused by degranulation of mast cells or basophils mediated by immunoglobulin E (IgE), and pseudo-anaphylaxis occurs without IgE mediation.
Biphasic anaphylaxis:…..CLICK & SEE
Biphasic anaphylaxis is the recurrence of symptoms within 72 hours with no further exposure to the allergen. It occurs in between 1–20% of cases depending on the study examined. It is managed in the same manner as anaphylaxis.
Anaphylactic shock:...CLICK & SEE
Anaphylactic shock is anaphylaxis associated with systemic vasodilation which results in low blood pressure. It is also associated with severe bronchoconstriction to the point where the individual is unable to breathe.
Pseudoanaphylaxis:….CLICK & SEE
The presentation and treatment of pseudoanaphylaxis is similar to that of anaphylaxis. It however does not involve an allergic reaction but is due to direct mast cell degranulation. This can result from morphine, radiocontrast, aspirin and muscle relaxants.
Active anaphylaxis:….CLICK & SEE
Active anaphylaxis is what is naturally observed. Two weeks or so after an animal, including humans, is exposed to certain allergens, active anaphylaxis (which is simply called “anaphylaxis”) would be elicited upon exposure to the same allergens.
Passive anaphylaxis:....CLICK & SEE
Passive anaphylaxis is induced in native animals which receive transfer of the serum experimentally from sensitized animals with certain allergens. Passive anaphylaxis would be provoked in the recipient animals after exposure to the same allergens.
SIGNS & SYMPTOMS :
Anaphylaxis can present with many different symptoms due to the systemic effects of histamine release. These usually develop over minutes to hours. The most common areas affected include: skin (80% to 90%), respiratory (70%), gastrointestinal (30% to 45%), heart and vasculature (10% to 45%), and central nervous system (10% to 15%).
Skin involvement may include generalized hives, itchiness, flushing, and swelling of the lips, tongue or throat….
Respiratory symptoms may include shortness of breath, wheezes or stridor, and low oxygen.
Gastrointestinal symptoms may include crampy abdominal pain, diarrhea, and vomiting.
Due to the presence of histamine releasing cells in the heart, coronary artery spasm may occur with subsequent myocardial infarction or dysrhythmia.
temA drop in blood pressure may result in a feeling of lightheadedness and loss of consciousness. There may be a loss of bladder control and muscle tone, and a feeling of anxiety and “impending doom”.
Anaphylaxis can occur in response to any allergen. Common triggers include insect bites or stings, foods, medication and latex rubber
Tissues in different parts of the body release histamine and other substances. This causes the airways to tighten and leads to other symptoms.
Some drugs (morphine, x-ray dye, and others) may cause an anaphylactic-like reaction (anaphylactoid reaction) when people are first exposed to them. Aspirin may also cause a reaction. These reactions are not the same as the immune system response that occurs with “true” anaphylaxis. However, the symptoms, risk for complications, and treatment are the same for both types of reactions.
Anaphylaxis can occur in response to any allergen. Common causes include:
•Drug allergies :Any medication may potentially trigger anaphylaxis. The most common to do so include antibiotics (?-lactam antibiotics in particular), aspirin, ibuprofen, and other analgesics. Some drugs (polymyxin, morphine, x-ray contrast and others) may cause an “anaphylactoid” reaction (anaphylactic-like reaction) on the first exposure. This is usually due to a toxic reaction, rather than the immune system mechanism that occurs with “true” anaphylaxis. The symptoms, risk for complications without treatment, and treatment are the same, however, for both types of reactions. Some vaccinations are also known to cause “anaphylactoid” reactions....CLICK & SEE
•Food allergies :The most common are peanut, tree nuts, shellfish, fish, milk, and egg. Severe cases are usually the result of ingesting the allergen…...CLICK & SEE
•Insect bites/stings : Venom from stinging or biting insects such as Hymenoptera or Hemiptera may induce anaphylaxis in susceptible people…..CLICK & SEE
Pollens and other inhaled allergens rarely cause anaphylaxis. Some people have an anaphylactic reaction with no known cause…..CLICK & SEE
Less common causes of anaphylaxis include:
*Muscle relaxants used during general anesthesia
Anaphylaxis triggered by exercise varies from person to person. In some people, aerobic activity, such as jogging, triggers anaphylaxis. In others, less intense physical activity, such as walking, can trigger a reaction. Eating certain foods before exercise or exercising when the weather is hot, cold or humid has also been linked to anaphylaxis in some people. Talk with your doctor about any precautions you should take when exercising.
Anaphylaxis symptoms are sometimes caused by aspirin, other nonsteroidal anti-inflammatory drugs — such as ibuprofen (Advil, Motrin, others) and naproxen sodium (Aleve, Midol Extended Relief) — and the intravenous (IV) contrast used in some X-ray imaging tests. Although similar to allergy-induced anaphylaxis, this type of reaction isn’t triggered by allergy antibodies.
If you don’t know what triggers your allergy attack, your doctor may do tests to try to identify the offending allergen. In some cases, the cause of anaphylaxis is never identified. This is known as idiopathic anaphylaxis.
Anaphylaxis is life-threatening and can occur at any time. Risks include a history of any type of allergic reaction.
Anaphylaxis is diagnosed with high likelihood based on clinical criteria. These criteria are fulfilled when any one of the following three is true:
1.Symptom onset within minutes to several hours of allergen exposure with involvement of the skin or mucosal tissue and any of the following: hives, itchiness, or swelling of the airway; plus either respiratory difficulty or a low blood pressure.
2.Any two or more of the following symptoms within minutes to several hours of allergen exposure: a. Involvement of the skin or mucosa b. Respiratory difficulties c. Low blood pressure d. Gastrointestinal symptoms
3.Low blood pressure within minutes to several hours after exposure to known allergen
Apart from its clinical features, blood tests for tryptase (released from mast cells) might be useful in diagnosing anaphylaxis.
Allergy testing may help in determining what triggered the anaphylaxis. In this setting, skin allergy testing (with or without patch testing) or RAST blood tests can sometimes identify the cause.
Anaphylaxis is an emergency condition requiring immediate professional medical attention. Call 911 immediately.
Check the person’s airway, breathing, and circulation (the ABC’s of Basic Life Support). A warning sign of dangerous throat swelling is a very hoarse or whispered voice, or coarse sounds when the person is breathing in air. If necessary, begin rescue breathing and CPR.
2.Calm and reassure the person.
3.If the allergic reaction is from a bee sting, scrape the stinger off the skin with something firm (such as a fingernail or plastic credit card). Do not use tweezers — squeezing the stinger will release more venom.
4.If the person has emergency allergy medication on hand, help the person take or inject the medication. Avoid oral medication if the person is having difficulty breathing.
5.Take steps to prevent shock. Have the person lie flat, raise the person’s feet about 12 inches, and cover him or her with a coat or blanket. Do NOT place the person in this position if a head, neck, back, or leg injury is suspected, or if it causes discomfort.
PROVIDING FIRST AID:
Although emergency medical help is essential, there are things that must be done to improve survival chances. If the person affected is conscious and having breathing difficulties, help them sit up. If they’re shocked with low blood pressure, they’re better off lying flat with their legs raised.
If the person is unconscious, check their airways and breathing, and put them in the recovery position.
If you know that the person is susceptible to anaphylaxis, ask if they carry a preloaded adrenaline syringe. If necessary, help the person inject it into their thigh muscle. If available, antihistamines and steroids should also be given.
•Do NOT assume that any allergy shots the person has already received will provide complete protection.
•Do NOT place a pillow under the person’s head if he or she is having trouble breathing. This can block the airways.
•Do NOT give the person anything by mouth if the person is having trouble breathing.
Paramedics or physicians may place a tube through the nose or mouth into the airways (endotracheal intubation) or perform emergency surgery to place a tube directly into the trachea (tracheostomy or cricothyrotomy).
The person may receive antihistamines, such as diphenhydramine, and corticosteroids, such as prednisone, to further reduce symptoms (after lifesaving measures and epinephrine are given).
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Anaphylaxis is a severe disorder that can be life-threatening without prompt treatment. However, symptoms usually get better with the right therapy, so it is important to act right away.
•Cardiac arrest (no effective heartbeat)
•Respiratory arrest (no breathing)
There aren’t many known risk factors for anaphylaxis, but some things that may increase your risk include:
*A personal history of anaphylaxis. If you’ve experienced anaphylaxis once, your risk of having this serious reaction is increased. Future reactions may be more severe than the first reaction.
*Allergies or asthma. People who have either condition are at increased risk of having anaphylaxis.
*A family history. If you have family members who have experienced exercised-induced anaphylaxis, your risk of developing this type of anaphylaxis is higher than it is for someone without a family history.
Immunotherapy with Hymenoptera venoms is effective against allergies to bees, wasps, hornets, yellow jackets, white faced hornets, and fire ants.
The greatest success with prevention of anaphylaxis has been the use of allergy injections to prevent recurrence of sting allergy. The risk to an individual from a particular species of insect depends on complex interactions between likelihood of human contact, insect aggression, efficiency of the venom delivery apparatus, and venom allergenicity. Venom immunotherapy reduces risk of systemic reactions below 3%. One simple method of venom extraction has been electrical stimulation to obtain venom, instead of dissecting the venom sac.
A potential vaccine has been developed to prevent anaphylaxis due to peanut and tree nut allergies if they are exposed to a small amount of peanuts or nuts. Although it shows some promise to reduce the likelihood of anaphylaxis in affected individuals, the vaccine has not yet been approved for marketing and distribution. Desensitization techniques are also being studied for peanut allergies.
•Avoid triggers such as foods and medications that have caused an allergic reaction (even a mild one) in the past. Ask detailed questions about ingredients when you are eating away from home. Also carefully examine ingredient labels.
•If you have a child who is allergic to certain foods, introduce one new food at a time in small amounts so you can recognize an allergic reaction.
•People who know that they have had serious allergic reactions should wear a medical ID tag.
•If you have a history of serious allergic reactions, carry emergency medications (such as a chewable form of diphenhydramine and injectable epinephrine or a bee sting kit) according to your health care provider’s instructions.
•Do not use your injectable epinephrine on anyone else. They may have a condition (such as a heart problem) that could be negatively affected by this drug.
Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.