Unexpected, lightning-fast, life-threatening

What is an anaphylactic shock?

An anaphylactic shock is the most severe form of an allergic reaction and can be fatal within a very short time. It is an excessive immune reaction in which large amounts of the messenger substance histamine are released. This causes, among other effects, a sudden widening of the blood vessels. As a result, blood pressure falls dramatically while the heart simultaneously tries to maintain circulation by increasing its rate.

The combination of a severe drop in blood pressure and the associated circulatory changes can cause a total collapse. Without rapid intervention there is a risk that vital organs will no longer receive sufficient blood supply, which can ultimately lead to multi-organ failure. In particularly dramatic courses, unconsciousness may occur after only a few minutes or cardiac arrest may ensue. People with existing cardiovascular disease are especially at risk because their bodies often cannot cope with such extreme strain.

What can trigger an anaphylactic shock?

An anaphylactic shock occurs when the body reacts excessively to substances that are normally harmless. These substances are called allergens and can be found in foods, insect venoms or medications. Typical foods that can trigger a severe reaction include nuts, peanuts, fish, shellfish, celery, soy, wheat, chicken eggs and cow's milk. In adults, painkillers and anaesthetics, certain antibiotics or radiographic contrast media are also common problems. Hypersensitivity to stings from wasps, bees, hornets or bumblebees is also widespread.

Triggers differ by age group: in childhood they are mainly foods, while in adults insect venoms and medications predominate. For wheat there is even a particular form of anaphylaxis that only occurs when ingestion is combined with physical exertion or the consumption of alcohol or painkillers.

There are also factors that can increase the risk. These include physical exertion, infections or the consumption of alcohol. Existing conditions such as asthma or cardiovascular disease also raise the likelihood of severe courses, particularly at older ages. In rare cases, anaphylaxis can even be triggered during desensitisation therapy.

It is important to know that not all allergic individuals immediately develop shock. Some affected people only show milder complaints after contact with the allergen, illustrating how variable the clinical expression can be between individuals.

Which symptoms indicate an anaphylactic shock?

An anaphylactic shock usually announces itself very quickly after contact with an allergen and affects several organ systems simultaneously. Possible first signs are sudden itching, a burning sensation on the palms, soles or in the mouth, a metallic taste or tingling on the tongue. Skin changes such as redness, hives or swelling of the lips, tongue and throat often occur and may make swallowing difficult.

In addition to these skin and mucosal reactions, many affected individuals also develop gastrointestinal complaints such as nausea, abdominal pain, cramps or vomiting. At the same time, breathing problems can occur in the form of hoarseness, coughing, wheezing sounds or progressive shortness of breath. Swelling of the laryngeal mucosa or a bronchospasm greatly worsen the situation and can impair oxygen supply.

The cardiovascular system is also sensitive: palpitations, a drop in blood pressure, arrhythmias up to circulatory failure are possible. A rapid fall in blood pressure is particularly dangerous, as it is defined differently in children and adults and represents a serious warning sign. In severe cases there may be clouding of consciousness, disorientation or feelings of panic, further indicating the critical state.

Medically, anaphylaxis is classified into four degrees of severity: from skin reactions with itching and flushing (Grade I) through additional gastrointestinal, respiratory and circulatory complaints (Grade II) to pronounced respiratory and circulatory disturbances with impaired consciousness (Grade III). Grade IV describes the rarest but most dangerous form with respiratory and circulatory arrest.

How does an allergic reaction develop?

An allergic reaction develops due to a malfunction of the immune system, which classifies normally harmless proteins as a threat. In people with an allergy, the first contact with an allergen leads to the formation of specific defence substances known as IgE antibodies. These target very specific proteins, for example from pollen, foods or insect venoms.

When affected individuals encounter the allergen again, the IgE antibodies bind to it and activate certain immune cells, including mast cells and basophils. These then release a variety of pro-inflammatory substances, including histamine, prostaglandins and leukotrienes. The effect of these mediators is seen in dilation of the vessels, increased permeability of vessel walls and constriction of the bronchi and veins.

In rare cases, reactions that are not mediated by IgE antibodies may also occur, such as in delayed-type allergies or so-called pseudoallergies. In these situations the inflammatory processes are triggered directly without the classic involvement of the immune system. Certain drugs can also set these mechanisms in motion and thus provoke an anaphylactic reaction.

Can an allergic shock recur?

Yes,an allergic shock can recur. Anyone who has already experienced anaphylaxis carries an increased risk of developing an equally strong immune reaction upon renewed contact with the same allergen. The tendency of the body to react so severely again remains, because it continues to regard the allergen as a threat.

How to act in an anaphylactic shock: practical tips

• Call the emergency services immediately (112), even if the affected person has already used their emergency kit. The emergency physician can initiate further vital measures and monitor the situation.
• Stop contact with the allergen. For example, stop an infusion, remove the sting after an insect sting — such as a bee sting — or prevent the affected person from continuing to eat a suspicious food.
• Position the patient correctly according to symptoms: for circulatory problems, elevate the legs; for breathing difficulties, sit the patient almost upright. These positions can decide between life and death.
• Place unconscious persons in the recovery position as long as they are breathing. This prevents the airway from being blocked by the tongue or vomit.
• Perform resuscitation immediately in case of cardiac or respiratory arrest. Follow the ABCD rule: clear the airway, ventilate, circulation by chest compressions and – if available – administer medications.
• Assist with the use of an adrenaline autoinjector. Remove the safety cap and press the pen firmly against the outer thigh. Press through clothing. Hold the pen in place for about ten seconds so the medication is fully delivered.
• Repeat the adrenaline injection if there is no improvement after five to ten minutes and another pen is available. Rapid action can stabilise the circulation and reduce swelling.
• Also give other preparations from the emergency kit, such as an antihistamine or corticosteroids. Although these act more slowly, they help to mitigate the reaction and prevent late sequelae.
• Monitor breathing, pulse and skin colour regularly until the emergency services arrive. If available, administering oxygen can also stabilise breathing.
• Remain calm and speak reassuringly to the affected person as long as they are conscious. Panic can worsen breathing difficulties and aggravate the shock.
• Pay attention to the special needs of children. If dizzy or with impaired consciousness, lay the child flat on their back with legs slightly elevated. If vomiting or fainting occurs, place the child in the recovery position to ensure breathing.
• Stay with the patient until help arrives. Do not leave them, as their condition can deteriorate within minutes. Your presence provides reassurance and allows prompt intervention.
• Encourage affected individuals to always carry an emergency kit and an anaphylaxis passport. Train relatives, friends or colleagues in the use of the autoinjector so that no time is lost in an emergency. For severe allergies, long-term specific therapy such as immunotherapy is often recommended to prevent future reactions.

An anaphylactic shock is an acute medical emergency that requires immediate action to avert danger to life. Only rapid treatment by a doctor and subsequent hospital care can prevent an anaphylactoid reaction from becoming life-threatening.