What is an allergic shock (anaphylactic shock)?

What is anaphylactic shock?

An allergic shock is the most severe form of an allergic reaction to a substance (allergen) that is harmless in itself. Within a very short time of coming into contact with the triggering allergen, the immune system reacts abnormally: Specific proteins in the immune system, known as IgE antibodies, activate certain cells, which then release inflammatory mediators such as histamine, leukotrienes and prostaglandins. This triggers a series of reactions in the body that can lead to the symptoms of anaphylactic shock and, in severe cases, even death. For example, this can result in a sudden dilation of the blood vessels, leading to a drastic drop in blood pressure and, ultimately, circulatory failure. Doctors refer to this as anaphylaxis, with the most severe form of anaphylaxis being known as anaphylactic shock.

How common is anaphylaxis?

Recent studies show that between seven and 50 out of every 100,000 people are affected by anaphylaxis each year. Anaphylactic shock proves fatal for one to three people per million inhabitants annually.

What causes anaphylactic shock?

Anaphylactic shock is triggered by contact with an allergen. Theoretically, this could be any substance to which the body is allergic.

However, the most common triggers of severe anaphylactic reactions are:

• Medicines (including penicillin, insulin, iodine-containing contrast agents and acetylsalicylic acid)
• Insect venoms (particularly bee venom, wasp venom and hornet venom)
• Foods (often eggs, nuts, fish and seafood, as well as wheat)

In children, food is the most common trigger of severe anaphylactic reactions, whilst in adults, insect venoms and medicines are also common triggers. Rarer or very rare triggers include natural latex, some spices and certain exotic fruits.

What factors can increase the risk of a severe anaphylactic reaction?

In addition to the triggers already mentioned, there are also additional risk factors that can increase the likelihood of a severe anaphylactic reaction, particularly in people who already suffer from allergies. These include:

• Acute infections
• Physical exertion
• Alcohol consumption
• Stress
• Advanced age
• Severe cardiovascular diseases
• Existing or poorly controlled bronchial asthma
• Use of non-steroidal anti-inflammatory drugs (NSAIDs)
• Mastocytosis

These risk factors may increase the likelihood of severe anaphylaxis and should therefore be given particular attention.

What are the symptoms of anaphylactic shock?

The symptoms of anaphylactic shock are varied and can affect the whole body. The skin, gastrointestinal tract, respiratory tract and cardiovascular system may all be affected. It is important to note that the more rapidly symptoms develop, the more dangerous the situation is.

Signs include:

• Swelling of the subcutaneous tissue
• A runny nose
• Watery eyes
• Shortness of breath
• Itching
• Rash all over the body
• Dizziness
• Difficulty swallowing and speaking
• Heart palpitations
• Nausea
• Digestive problems

What are the different degrees of severity of anaphylaxis?

Anaphylactic reactions are usually classified into four severity levels, with symptoms potentially manifesting in the skin, gastrointestinal tract, respiratory tract and cardiovascular system:

What happens during an anaphylactic reaction?

The symptoms of anaphylactic reactions usually set in very suddenly and can progress very rapidly. Within minutes, symptoms can worsen, leading to shock and even death. However, there are also cases in which the reaction stops spontaneously and resolves over time. The symptoms may occur simultaneously or in succession, and it is possible for circulatory reactions to occur first, without any prior signs of skin or respiratory reactions. Although the most common course of events is for symptoms to begin spontaneously immediately after contact with the allergen, there are also delayed-onset anaphylactic reactions that do not begin until hours after contact with the allergen. In five to 20 per cent of cases, following treatment, symptoms may recur, usually after six to 24 hours.

How does an anaphylactic reaction manifest in children?

The main symptoms of anaphylactic reactions are essentially the same in children and adults, but the severity of the symptoms can vary. In younger children in particular, restlessness and withdrawn behaviour are often observed at the onset, even before any objective symptoms are detectable. Children are generally not yet able to communicate that their circulation is becoming weak. Instead, they become tired and show an increased need for sleep. If skin symptoms or itching then develop, one should be particularly vigilant.

How is anaphylactic shock diagnosed?

Anaphylactic shock is diagnosed on the basis of characteristic criteria for anaphylaxis. These include:

• The sudden onset of skin symptoms together with respiratory symptoms or a sudden drop in blood pressure.
• The sudden onset of symptoms in two or more organ systems, such as the skin, gastrointestinal tract, respiratory tract or circulatory system, following contact with a probable allergen.
• A drop in blood pressure following contact with an allergen known to the patient.

As the clinical symptoms are not always clear-cut, the doctor must also rule out other acute reactions, such as other forms of shock or cardiac arrhythmias.

What treatments are available?

Anaphylactic shock is a medical emergency requiring immediate action. The priority is to stop the allergen from entering the body straight away – for example, by removing a bee sting or stopping the administration of a medicine that has triggered the anaphylaxis. For the subsequent acute treatment, the most important medication is adrenaline, which simultaneously reduces symptoms affecting the heart, skin and airways. When administered by injection, it acts faster than any other medication, and if there is swelling of the larynx and breathing difficulties, it is recommended to administer adrenaline via a breathing mask alongside oxygen, in addition to the injection. It is also crucial to administer sufficient fluids via a drip as quickly as possible, as this stabilises the circulation. Antihistamines and glucocorticoids also act to counteract the anaphylactic reaction at its source.

What are the most important emergency measures?

The most important emergency measures in the event of a severe allergic reaction that could lead to anaphylactic shock are crucial for the safety and survival of the affected person. Here are the measures that should be taken in various situations:

• Call an ambulance: This is the very first step to summon professional help capable of providing life-saving treatment.

If the person affected is conscious, the following steps should be taken:

• Remove the trigger: If the trigger of the allergic reaction is known or visible (e.g. a bee sting), it must be removed.
• Check their breathing: If the person affected is conscious, you must ensure they are getting enough air.
• Sit them up: The person affected should sit with their upper body raised so that they can support themselves with their arms.
• Stay calm: Reassure the person affected and encourage them to breathe slowly and deeply.
• Cooling for swelling: If there is swelling, apply ice wrapped in cloths to the affected area, or use ice cubes or ice cream if the swelling is in the mouth or throat.
• Administering emergency medication: If the person affected has emergency medication with them, you should help them to take it.

If the person affected is conscious, the following steps should be taken:

• Check for consciousness and breathing: Check whether the person is conscious by speaking to them and gently shaking them.
• Recovery position or resuscitation: Check for breathing by tilting the head back for a maximum of ten seconds. If normal breathing is present, place the person in the recovery position. If there is no normal breathing, resuscitation must be started immediately.

How can you prevent an allergic shock?

The best way to prevent anaphylactic shock is to avoid the allergen. However, as with insect stings, for example, this is not always possible. In such cases, long-term immunotherapy is an option, whereby the body is slowly and gradually ‘acclimatised’ to increasingly higher doses of the allergen, so that the immune system ultimately no longer reacts to it. If you know you have an allergy, you should always carry an adrenaline auto-injector with you and administer it yourself upon contact with a trigger or if symptoms occur. This usually stops the anaphylactic reaction, at least temporarily. It is also important for people with known allergies to carry an emergency kit and to inform those around them of the procedure to follow in an emergency.