When the body recognizes an allergen and an immune response occurs, the body remembers the allergen and makes an antibody called ‘IgE’ against a specific allergen. When the allergen, which initially triggered an immune response, enters our body again, it binds to IgE attached to the surface of inflammatory cells and releases various inflammatory-mediated chemicals within minutes. The effects of these chemicals cause severe systemic reactions such as shock symptoms such as acute respiratory distress, decreased blood pressure, and loss of consciousness. This process can occur in a very short period of time, and symptoms appear within a few minutes even after reexposure to very small amounts of the allergen. On the other hand, in terms to be distinguished from this, a case where similar clinical features appear but lack of evidence due to an immune response is called an anaphylactoid reaction.
Anaphylaxis can occur for a variety of reasons.
In theory, all kinds of foods are likely to cause anaphylaxis. Common examples include flour, buckwheat, peanuts, and crustaceans such as shrimp and crayfish. Although rare, simply eating food does not induce anaphylaxis, but symptoms may appear when you exercise after eating, such as running or playing basketball, which is called ‘food dependent exercise-induced anaphylaxis.’
Again, all drugs can cause anaphylaxis. Typical examples are penicillin or cephalosporin-based monolactam antibiotics, nonsteroidal anti-inflammatory analgesics, and contrast media used in computed tomography (CT). And blood products such as red blood cells or plasma can also cause anaphylaxis.
It can be caused by bee stings or ant bites.
Regardless of food intake, exercise alone can lead to anaphylaxis.
During hemodialysis, anaphylaxis may occur through complement activation by the dialysis membrane, and the cause may not be found. This is called idiopathic anaphylaxis.
After exposure to the cause, symptoms are usually acute within 30 minutes, and symptoms develop in various organs as follows.
1) Respiratory system
It causes convulsions and contractions of the bronchial muscles, resulting in shortness of breath and wheezing (a wheezing sound from the narrowing of the bronchi), hypoxia, stuffy nose and runny nose.
2) Circulatory system
As blood pressure decreases, blood flow to the brain decreases, resulting in headaches and dizziness.
3) Digestive system
Nausea and vomiting occur, and blood flow to the gastrointestinal tract decreases, causing abdominal pain.
Initially, it may be accompanied by a tingling sensation around the mouth or face, or dryness in the mouth. Hives, itching, redness on the skin or mucous membranes, or angioedema on the lips or tongue may occur. In particular, if severe angioedema occurs in the larynx, centering on the uvula, the airway may be blocked and suffocation may occur, so caution is required.
Diagnosis through clinical symptoms is the most important. Hives or angioedema develops on the skin or mucous membrane within a short period of time after exposure to the cause of anaphylaxis, and satisfies two or more of respiratory symptoms such as dyspnea, circulatory symptoms such as hypotension, and digestive symptoms such as nausea and vomiting. If you do, or if you know the causative agent, you can diagnose even if there is a decrease in blood pressure.
For some antigens, a skin test is helpful for diagnosis. However, there is a high possibility that anaphylaxis is caused by the fact that a standard reagent has not been established and a positive skin test result is the cause of anaphylaxis. Detection of allergen-specific IgE in serum may also be helpful. For a more accurate diagnosis, a provocation test can be carefully performed. This is a method of reexposing the suspected substance to the patient in the same way as the symptoms occurred. However, since it may cause severe symptoms, it should be performed only by an experienced examiner when absolutely necessary.
When symptoms occur, first aid measures should be taken to raise blood pressure and secure airways. At this time, it is most important to administer epinephrine, and if there is no response to the treatment, you can try up to 3 doses every 5 to 15 minutes. When supplying fluid and reducing oxygen saturation, oxygen supply is also important. In addition, steroids and antihistamines can be administered as an auxiliary treatment.
Most will recover without complications. However, if severe blood pressure decrease persists or if you have a heart or brain disease, organ damage due to hypotension may remain a complication.
Avoiding exposure to the causative agent is the most obvious prevention. However, in many cases it is difficult to avoid causative substances such as idiopathic anaphylaxis and bee venom anaphylaxis, and even if the causative agent is known, it is inevitable to be re-exposed. It is recommended to carry it.
Epinephrine self-injection (brand name: JEXT) can be purchased at the Orphan Medicine Center by receiving a prescription from an allergist.
In the case of food-dependent exercise-induced anaphylaxis, avoid the associated food exposure and limit exercise if exposed.
It is also helpful to always tell people around you what is causing your symptoms and to carry a card with the contents. Through this, it is possible to prevent the re-administration of the causative drug when receiving a prescription at the hospital, and in case of a loss of mind and a fall, the surrounding person can guess the cause and help to implement appropriate emergency measures. If food is the cause, avoid eating that food. Especially when you eat out, you have to be more careful. However, no matter how careful you are, you may be exposed unexpectedly.