What is an anaphylactic reaction

4.6.2009

Anaphylactic reaction is an acute response of the body to contact with an irritant (allergen). It is a severe type of allergic reaction. It typically manifests itself in a rash and swelling of the skin and mucous membranes that occur shortly after contact with the allergen. In the most severe cases, it can lead to shock and death of the affected person.

What you may not have known...

The earliest records of allergy as a hypersensitivity to certain foods or drinks date back to the 1st century BC. In modern medicine, the hypersensitivity of the body to a particular substance was studied in experimental dogs by the French physiologist Charles Richet in 1902. Allergies in humans were not described until 4 years later by the Austrian paediatrician Clemens von Pirquet. He observed that people develop allergic reactions when they repeatedly come into contact with irritants (allergens).

The condition for an anaphylactic reaction is usually previous contact with the irritant - sensitisation. You can ingest it, inhale it or just touch it with bare skin. Your immune system remembers the "intruder" and triggers a violent defence reaction the next time it comes into contact. You are most at risk of anaphylaxis if you have a history of hypersensitivity to a substance. You can develop an allergy to virtually anything. However, some allergens are more common. These include certain types of food (e.g. peanuts, shellfish or fruit), insect stings or certain medicines (e.g. penicillin).

Foreign substances (allergens) that your body comes into contact with trigger the production of antibodies. This is the mechanism by which your immune system defends you against their possible harmful effects. In the case of anaphylaxis, an exaggerated immune reaction occurs after contact with the allergen. The excessive production of antibodies affects other immune cells, which are then responsible for the manifestations of the allergy.

How does it manifest itself...

The main manifestations of an allergic reaction include rash and itching. The symptoms can escalate to anaphylaxis. Uncomfortable shortness of breath quickly sets in. This is caused by swelling of the mucous membranes in your respiratory tract. Very little oxygen reaches your lungs through the narrowed breathing tube and you have to exert increased effort to breathe. In the most severe cases, you can start to suffocate.

The immune response will affect the behaviour of your whole body. It has a dangerous effect on your circulatory system. Blood stops circulating and accumulates in the tissues. Suddenly your blood pressure drops. With a critical drop in blood flow through the blood vessels, the brain does not receive its usual supply of oxygen and nutrients. You go into shock and rapidly lose consciousness. Without effective intervention, you're at risk of death.

As will be confirmed...

Anaphylactic reaction can be an acute, life-threatening condition. In the most severe cases, it can lead to shock and death. It requires immediate first aid and medical attention as soon as possible. When it occurs, there is no time for complicated testing. Increased caution should be exercised even with seemingly minor allergic manifestations.

An anaphylactic reaction should be considered when suddenly developed discomfort accompanied by itchy eyes, rash (urticaria) and shortness of breath occurs within a short time (within a few minutes) after contact with a substance (food, insect, etc.). Other symptoms may include abdominal cramps accompanied by nausea and vomiting or diarrhoea and reddening of the skin with swelling of the whole body.

An anaphylactic reaction usually occurs only with repeated contact. But you can't count on that. Many allergens occur naturally in forms you would not expect. The first apparent exposure may have been preceded by several previous ones.

The occurrence of an anaphylactic reaction cannot be predicted. It is therefore advisable to determine the presence and type of hypersensitivity even at mild allergy symptoms and to undergo appropriate treatment. Allergy testing is used for this purpose.

How to treat...

It is important to start treatment at the beginning of an allergic reaction. The main principle is to break the contact of the affected person with the allergen. With weakness and dizziness, lie on your back and raise your legs above the level of your head. Allergy symptoms can be relieved by antihistamines. These will relieve the unpleasant itching. If you have difficulty breathing, bronchodilators are in order to dilate your airways. Corticosteroids can also suppress an allergic reaction. Your allergist will prescribe all the necessary medications.

The most effective means of managing a severe anaphylactic reaction is adrenaline. Its timely administration can reverse the course of your body's response to the presence of the allergen and thus save your life. It will cause your blood vessels to constrict and increase your heart rate. It will prevent the development of swelling and relieve airway constriction. The decision to administer epinephrine is usually made by your doctor. People at increased risk of an anaphylactic reaction or those who have already experienced one may be given a special adrenaline kit for easy administration. They should carry it with them at all times and instruct those in their immediate vicinity on how to use it.

It is important to call for professional help immediately after giving first aid. However, the sick person must not be left unattended. Monitor his/her state of consciousness and breathing. In the event of respiratory and cardiac arrest, start cardiopulmonary resuscitation immediately. In the event of airway obstruction, minor surgery to open the breathing tube in the neck may need to be performed urgently. Respiration and cardiac function should be monitored even after the acute response has been managed. Therefore, a hospital stay usually follows.

What next...

The severity of an anaphylactic reaction is related to the speed of its onset after contact with the allergen. The faster it develops, the more threatening it is to the sufferer. The most severe cases can be fatal. The risk can be significantly reduced by providing early help and initiating appropriate treatment.

The course of the reaction also depends on the extent of the disability. If the reaction is only local in the airways, allergic rhinitis, allergic sinusitis, swelling of the airways or an allergic asthma attack may occur. In the skin, atopic eczema, urticaria and swelling occur. Reactions in the digestive tract are manifested by vomiting, abdominal pain and diarrhea. When a general anaphylactic reaction occurs in multiple systems simultaneously, life-threatening anaphylactic shock develops.

How to avoid all this...

The most effective prevention of an anaphylactic reaction is to avoid contact with irritants (allergens). This can be done effectively in most cases where the trigger of your reaction is known. Problems can arise with allergens coming into contact with the respiratory tract. In pollen allergy, for example, it is necessary to limit exposure to the outdoors in sunny, dry weather when irritant plants are in bloom. A pollen calendar or pollen newsletters will give you an idea of the current situation.

Hyposensitisation is another way to prevent the development of a severe allergic reaction or at least mitigate its course. The principle is the repeated and prolonged administration of increasing doses of the allergen. This has been shown to decrease the degree of allergy and increase your tolerance to harmful allergens. Consult your doctor about the possibilities and suitability of hyposensitisation.

Source:

U Lékaře.cz