What is anaphylaxis?
Anaphylaxis is a medical term for a rapid systemic allergic reaction, which often is called anaphylactic shock. Anaphylaxis sometimes occurs when a person is exposed to an allergen to which the person is allergic or sensitive. Many materials can act as an allergen. Even very small amounts of the allergen can cause a life-threatening anaphylactic reaction. Anaphylaxis can occur after ingestion of the allergen, but also after its inhalation, skin contact or an injection of the substance. The most severe form of anaphylaxis can sometimes lead to death within minutes if not treated immediately. Severe anaphylactic reactions are very rare lucky compared to more "normal" allergic reactions. The primary treatment of anaphylaxis consists of an injection of epinephrine, an agent which is sometimes combined with other medications.
A difference between an anaphylactic reaction and an anaphylactoid response is that one has to be sensitized in the first case for the antigen, it is necessary in other words, antibodies (IgE) to create, before the reaction can take place. They will never have a reaction at the very first contact with an allergen (such as latex). In anaphylactoid reactions such sensitization is not necessary: the allergens themselves have a vasoactive effect, which stimulates histamine, such as bee venom. There is no detectable IgE.
Anaphylaxis shock
One speaks of an anaphylactic shock when the body by dilation of the blood vessels as a result of the release of a large amount of histamine hit in shock. Together with other symptoms shock may also occur, but this is not necessary.
Treatment of an anaphylactic emergency
An anaphylactic reaction is a medical emergency due to the acute constriction of the airways that can occur within a few minutes after the onset of the allergic reaction. It is vital to seek help immediately to prevent brain damage from lack of oxygen. In an anaphylactic reaction professional help is necessary, but other first aid measures such as mouth-to-mouth resuscitation and administering adrenaline can be applied before the ambulance on site. Mouth-to-mouth resuscitation may be possible if the airway of the patient through the allergic reaction are close, but can save lives in other cases. Many patients diagnosed with "anaphylaxis" has already been asked carry an epinephrine auto-injector (EpiPen or a similar product) by itself for the immediate administration of adrenaline. This is an injection pen where the needle spreads out as soon as the lock is removed and the cup on the body part to be injected (by default this is the side of the upper leg) is inserted. This injection does not have to be administered by a physician.
The Beta-2 adrenergic receptors in the lungs react to adrenaline. This relaxed by an allergic asthma attack or anaphylactic reaction constricted bronchi themselves. Adrenaline dilates the airways and constricts blood vessels. This has the result that the life-threatening anaphylaxis was caused by low blood pressure that rises again, and the heart beats more powerful. The administration of adrenaline therefore sometimes is a life-saving measure.
Signs and symptoms of anaphylaxis
Anaphylaxis is usually associated with many different symptoms that last a few minutes or hours. Symptoms appear on average within 5 to 30 minutes if the cause is a substance which enters directly into the circulation (intravenously). This average increases to 2 hours if the cause is food eaten. The symptoms occur mainly in the following areas: skin (80-90%), lungs and respiratory tract (70%), stomach and intestines (30-45%), cardiovascular (10-45%) and central nervous system (10-15%). The reactions usually occur in two or more of these systems on.
Skin
The symptoms are often bumps on your skin (hives), itching, red face and red skin (flushing) or swollen lips. Patients with swelling under the skin (angioedema) may have for itchy feeling that their skin is on fire. The tongue or throat can swell in 20% of cases. In addition, patients may also suffer from a runny nose and swelling of the mucous membrane on the surface of the eyes and eyelids (conjunctiva). The skin can also blue colors (cyanosis) by a lack of oxygen.
Respiratory tract
Examples of signs and symptoms of the respiratory tract are shortness of breath, whistling or wheezing difficulty breathing with a low tone (wheezing), or whistling or wheezing difficulty breathing with a high tone (stridor). Wheezing with a low tone is usually caused by spasms of the muscles in the lower part of the airways (bronchusspieren). Wheezing with a high tone is caused by swelling in the upper airway which reduces the passage. Hoarseness, pain on swallowing or cough may also occur.
Cardiovascular
The blood vessels of the heart can suddenly contract (coronary artery spasm) because certain cells from releasing histamine in the heart. This disrupts the blood supply to the heart causing heart cells to die (heart attack), heart too fast or too slow beats (arrhythmias), or making the whole heart can stop beating (cardiac arrest). Patients who already have heart disease are at increased risk of heart problems caused by anaphylaxis. A fast heart rate low blood pressure is most common, but still has 10% of patients with anaphylaxis, a slow heart rate (bradycardia) in combination with low blood pressure. (This combination of slow heart rate and low blood pressure is known as the Bezold-Jarisch reflex). The patient may feel dizzy or lose consciousness as the blood pressure drops. This low blood pressure may be caused by the blood vessels are dilated (distributive shock) or when the chambers of the heart failure (cardiogenic shock). In very rare cases low blood pressure is the only symptom of anaphylaxis.
Other symptoms
Gastrointestinal symptoms include abdominal cramps, diarrhea and vomiting. The patient may be confused, lose control of the bladder and pelvic pain have that feels like uterine cramps. By dilating the blood vessels around the brains headache may occur. The patient may also feel anxious and imagine that he or she is going to die.
Anaphylaxis causes
Anaphylaxis can be caused by a reaction of the body to almost any foreign substance. Poison from insect bites or stings, foods and medications are common causes. Food is the most common cause in children and young adults. Medication and insectenbeten- or stabbing his frequent causes in older adults. Less common causes include physical factors, biological substances (such as sperm), latex, hormonal changes, food additives (such as mono-sodium glutamate, and food dyes), and medication that is applied to the skin (such as ointment, cream or lotion). Physical exertion or high or low temperatures may also cause anaphylaxis because certain tissue cells (known as mast cells) release chemicals that initiate the allergic reaction. Anaphylaxis caused by physical exertion often related to eating certain foods. When anaphylaxis occurs when a person anesthesia is administered, than are the most common causes medication that is given to cause paralysis (neuromuscular blocking agents), antibiotics, and latex. In 32-50% of cases the cause is unknown (idiopathic anaphylaxis).
Food
Many types of food can cause anaphylaxis, even when it is eaten for the first time. In the West, the most common causes are eating or come in contact with peanuts, wheat, tree nuts, shellfish, fish, milk and eggs. In the Middle East, sesame is a known trigger of anaphylaxis and in Asia that rice and chickpeas. Severe cases are usually the result of food from the food, but some people already have a strong reaction when the food comes into contact with a body part.
Children can outgrow their allergies and have no problems with their sixteenth year of life with food they have responded anaphylactic at a younger age. For anaphylaxis caused by milk or eggs, this applies in 80% of cases and for anaphylaxis by peanuts in 20% of cases.
Medication
Any drug can cause anaphylaxis. Mostly it comes to beta-lactam antibiotics (such as penicillin) followed by aspirin and NSAIDs (non-steroidal anti-inflammatory drugs). Someone who is allergic to one specific NSAIDs can usually use another without causing other means anaphylaxis. Other common causes of anaphylaxis are chemotherapy, vaccines, protamine (semen) and herbal medicines. Some drugs, including vancomycin, morphine and medication in order to optimize X-ray images (X-ray contrast agents), cause anaphylaxis by damaging certain cells in tissues causing the cells release histamine (degranulation of mast cells).
How often occurs a reaction to a drug, depends in part on how often it is administered to the patient, and for a part of how the drug works in the body. Anaphylaxis caused by penicillins or cephalosporins occurs only after these substances bind to proteins in the body, and some bind more easily than others. Anaphylaxis caused by penicillin occurs to 10,000 people treated at 1 in 2,000. Anaphylaxis with death as a consequence occurs in 1 in 50,000 treated people. Anaphylaxis caused by aspirin and NSAIDs occurs in about 1 in 50,000 people. If someone has had a reaction to penicillin than is the risk of a reaction to cephalosporins have become larger, but still less than 1 in 1000. older medication that was used for the improvement of X-rays (X-ray contrast agents) elicited responses in 1% of the cases, . Newer X-ray contrast agents with a lower osmolarity cause reactions in 0.04% of cases.
Anaphylaxis diagnosis
When a person is within a few minutes / hours after exposure to an allergen to any one of the following three phenomena, then it is very probable that the person has an anaphylactic reaction:
- Disease of the skin or mucous membranes plus or breathing problems or low blood pressure
- Two or more of the following symptoms:
b. breathing problems
c. low blood pressure
d. gastrointestinal complaints
- Low blood pressure after exposure to an allergen known
Classification
Anaphylaxis is divided into three main groups.
In an anaphylactic shock be dilated blood vessels in almost the entire body (systemic vasodilatation), through which a blood pressure is produced which is at least 30% lower than the normal blood pressure of the patient, or 30% lower than the standard values for blood pressure.
There is biphasic anaphylaxis when symptoms return within 1 to 72 hours, even though the patient is not again been in contact with the allergen that the first reaction is caused. Some studies state that in 20% of cases of anaphylaxis to go biphasic anaphylaxis. If symptoms return then that is often within 8 hours. The second anaphylactic reaction is treated in the same way as the first.
Pseudo-anaphylaxis or anaphylactoid reactions are older names for anaphylaxis which is not the result of an allergic reaction but of direct damage of mast cells (mast cell degranulation). The name that is currently used by the World Allergy Organization 'non-immune anaphylaxis'. Some say it is better to completely stop using the old terms.
Allergy tests
With allergy tests can be tried to determine the cause of anaphylaxis has been. Certain foods and poisons his skin allergy tests (such as the patch test) available. Blood tests for specific antibodies may be useful in order to determine whether it is hypersensitivity to milk, egg, peanuts, tree nuts or fish. With a skin test is also to determine whether there is a penicillin allergy, but there are no skin tests for other drugs. Non-immune forms of anaphylaxis are to be fixed only by studying the medical history of the patient, or by exposing the patient to an allergen that the reaction in the past, might have caused. Non-immune anaphylaxis can not be determined with skin tests or blood tests.
Is the diagnosis?
Sometimes it is difficult to distinguish between anaphylaxis, asthma, passing out due to lack of oxygen (syncope) and panic attacks. People with asthma usually have no itching or gastrointestinal complaints. When someone faints, skin is pale and there is no rash. A person with a panic attack can have a red skin, but no hives. Other conditions that cause similar symptoms, food poisoning from spoiled fish (scombroïdose) and infection with certain parasites (anisakiasis).
Anaphylaxis prevention
The best way to prevent anaphylaxis is to avoid anything that caused the reaction in the past. If you can not, there are treatments that keep the body hopefully no longer responds to a known allergen (desensitization). Treatment of the immune system (immunotherapy) and Hymenoptera poisons effective as desensitization at 80% to 90% of adults and 98% of children who are allergic to bees, wasps, hornets and fire ants. Immunotherapy by mouth can be effective in desensitization of people with allergies to certain foods, such as milk, eggs, nuts and peanuts; However, such treatment is often accompanied by serious side effects. Desensitization is also possible in many medicines, but most people can avoid problematic drugs but just better. In people who are allergic to latex may be important to avoid foods that contain substances that are similar to latex (cross-reactive foods), which include avocados, bananas and potatoes.
Anaphylaxis treatment
Anaphylaxis is a medical emergency where lifesaving intervention may be necessary, such as keeping the airway, supplemental oxygen, large volumes of intravenous fluids and close monitoring. Epinephrine is the drug in these situations where the preferred. Except epinephrine antihistamines and steroids are often used. After the condition of the patient is normalized, he or are still 2 to 24 hours are observed in the hospital in order to ensure that the symptoms did not return, which can be used as the patient has biphasic anaphylaxis.
Paramedical treatment prior to transport to the hospital includes the injection of epinephrine, the administration of oxygen, and if necessary intubation. If persistent angioedema is often administered for a long period of time oxygen. In rare cases, a tracheotomy is performed.
Epinephrine
Epinephrine (adrenaline) is the primary treatment for anaphylaxis. There are no reasons not to use (there is no absolute contraindication). It is recommended to inject epinephrine in the thigh muscle once anaphylaxis thought. The injection can be repeated every 5 to 15 minutes if the patient does not respond well to treatment. In 16 to 35% of the cases a second dose is needed. More than two doses are rarely required. Injecting into the muscle (intramuscular injection) is better than injection under the skin (subcutaneous injection) because the drug in an injection under the skin can be absorbed too slowly. Minor problems with epinephrine include tremors, anxiety, headaches and palpitations.
Epinephrine may not work in people taking beta-blockers. If epinephrine in which people do not work, glucagon can be administered through a vein. Glucagon has a mechanism of action in which no beta-receptors are involved.
Epinephrine may, if necessary, also as a dilute solution to be injected into a vein (intravenous injection). Intravenous epinephrine may be associated with an irregular heartbeat (arrhythmia) and heart attack (myocardial infarction). With an auto-injector of epinephrine (EpiPen), people with anaphylaxis self inject epinephrine into a muscle. This auto-injectors are available in two strengths: one for adults and children weighing more than 25 kg, and one for children from 10 to 25 kg.
Additional resources
In addition to epinephrine, antihistamines are frequently used. These resources are considered active on theoretical grounds, but there is very little evidence that they are also really effective in the treatment of anaphylaxis. In a Cochrane review (some form of scientific research) are no scientific studies of good quality were found in 2007, which recommend the use of antihistamines. Antihistamines have any thoughts to no effect on the accumulation of fluid or cramps in the airways. Corticosteroids make any difference most likely when someone has an anaphylactic reaction. Corticosteroids may be used in the hope of reducing the risk of biphasic anaphylaxis, but it is not certain that they can prevent future anaphylaxis. Salbutamol administered via a breathing machine (nebulizer), can help when epinephrine gives no relief of bronchospasm. Methylene blue is used in patients who do not respond to other measures because this substance smooth muscles to relax.
Preparation
People who run the risk of anaphylaxis, we recommend a "allergy action plan 'to prepare. Parents should inform the school about their child's allergies and what to do if there is an anaphylactic emergency. The action plan usually includes use of epinephrine auto-injectors, the recommendation to wear a bracelet with medical information and education about avoiding situations that can cause anaphylaxis. In certain causes of anaphylaxis, it is possible to make the body less susceptible to allergic reactions (allergen immunotherapy). With this type of treatment it may be possible to prevent future anaphylactic reactions. A long-term desensitization injections under the skin has been proven effective against insect stabbing, while desensitization by mouth is effective in many foods.
Risk
Anaphylaxis is a year, at 4 to 5 per 100,000 for people, with a lifetime risk of 0.5% to 2%. These percentages appear to be increasing. The number of people with anaphylaxis was in the 80s of the last century about 20 per 100,000 per year, whereas in the 90s was about 50 per 100,000 per year. The increase seems to especially anaphylaxis to lie through food. The risk is greatest in young people and women.
Anaphylaxis is currently training in the United States up to 500 to 1,000 deaths per year (2.4 per million) in the UK to 20 deaths per year (0.33 per million) and Australia to 15 deaths per year (0.64 per million). Mortality rates have declined between 1970 and 2000. In Australia, you will die from anaphylaxis caused by food especially in women place, while men mainly occurs through insect bites. Medicines are the most common cause of death from anaphylaxis.