Anaphylactic reactions. Anaphylactic shock

The terms "allergic reactions", "Quincke's edema", "anaphylactic shock" appeared in medicine relatively recently, at the beginning of the twentieth century. They were introduced to the world by a French scientist, Nobel laureate in medicine, physiologist Charles Richet. Then his idea in domestic medicine was picked up by Alexander Mikhailovich Infrequently, he improved methods of administering drugs to patients with a history of allergies. Later emergency protocols were developed for such patients, and the number of fatalities decreased. However, despite modern medicines, the mortality rate from anaphylaxis is still high.

Definition

In a broad sense, an allergy is an increase in the sensitivity of the immune system to a specific pathogen and its violent reaction when it comes back into contact with it. Allergic reactions are of several types:

• immediate, or anaphylactic;
• cytotoxic (antibodies cross-interact with body tissues);
• immunocomplex (vascular damage by activated immune complexes);
• slow, or cell dependent.

Anaphylactic reactions are a manifestation of an allergic reaction of the first type, that is, immediate.

In addition, in clinical practice, anaphylactoid reactions are also distinguished , which are similar in clinical manifestations to anaphylaxis, but the mechanism of their formation is due to the activation of inflammatory cells by foreign substances, complement proteins, and not by antigen-antibody complexes.

Causes

Initially, anaphylactic allergic reactions occurred when a toxic substance entered the human body. An example is the bites of poisonous insects and reptiles. But in the modern world, an organism can react incorrectly even to familiar, banal things:

1. Food products - honey, milk, nuts, eggs, seafood, chocolate, citrus fruits.
2. Medicines - hormones, contrast agents, vaccines and serums, anesthetics.
3. Plants and animals - pollen of flowers, fungus, animal hair, dust mites.
4. The ambient temperature is cold / heat.
5. An increased likelihood of allergies in people with asthma, vasomotor rhinitis, eczema.

This is only a short, very generalized list of what can cause an allergy in an average person. In addition, if similar reactions are observed in first-line relatives, then most likely the child will also have the same reaction.

Reaction development principle

Allergic reactions of the anaphylactic type are associated with a pathological response of the immune system to the ingestion of foreign agents. Normally, at the first encounter with an antigen, the body produces M immunoglobulins, and at a second, G. But sometimes this process gets confused. Anaphylactic type of reaction occurs when the population of specific immunoglobulins E. increases . They appear from the moment of contact with the substance for the first time, but at first they do not manifest themselves. Instead, they are fixed on the surface of mast cells (basophils) and wait in the wings. If a person re-contacts with an antigen, then IgE activates basophils and releases inflammatory mediators such as histamine, cytokines, interleukins, prostaglandins and leukotrienes. With a large number, they systemically affect the body's tissues, causing edema, vasodilation, contraction of smooth muscles in the walls of hollow organs, respiratory failure, increased secretion of glands. An inflammation zone forms at the site of penetration of the allergen. This is the phase of immediate hypersensitivity.

But the development of the anaphylactic reaction also has a second period, or phase, called delayed hypersensitivity. To form the focus of inflammation, chemotaxis enters cells - lymphocytes, neutrophils, eosinophils, macrophages. They contain substances in the cytoplasm that are necessary for combating a foreign agent, but instead destroy the body’s own tissues, and instead they form connective tissue. As a rule, a delayed reaction occurs six hours after the acute and lasts up to two days.

Systematization of anaphylactic reactions

Types of anaphylactic reactions are divided according to the severity of their clinical manifestations. Characteristic features help to quickly assess the condition of the patient and provide him with the necessary assistance.

1. Mild anaphylactic reactions do not pose a threat to human life. Subjectively, patients describe them as a feeling of paresthesia - tingling or heat in the limbs, which is combined with a slight swelling of the mucous membranes of the nose, mouth or eyelids. Possible sneezing, lacrimation, itching. Symptoms appear and disappear during the day.
2. The moderate severity is manifested in the form of bronchospasm, reactive edema of the mucous membrane of the larynx and bronchi. People have severe shortness of breath, cough, air passes into the lungs with a characteristic whistling sound. In such conditions, Quincke's edema, urticaria are possible . There may be general intoxication, such as nausea, vomiting, headache, and fever. In some cases, erythema, severe itching, nervous excitement.
3. Severe anaphylactic reactions begin acutely and initially, as a rule, look like a mild type. Then, after a few minutes, the second stage begins with bronchospasm, edema of the upper respiratory tract and bronchi, respiratory failure. Then cyanosis appears, there may be respiratory arrest. The next step is to generalize the symptoms. The mucous membrane swells not only in the respiratory system, but also in the digestive tract. This leads to impaired peristalsis, vomiting, diarrhea and abdominal pain. From the nervous system, epileptic seizures, a violation of the innervation of the pelvic organs can occur. Systemic expansion of the peripheral vessels and the release of the liquid part of the blood into the surrounding tissues due to edema provokes a drop in pressure up to collapse. The severity of the condition depends on the speed of development of the process, they are directly dependent: the faster, the worse the prognosis. Until death.

Local symptoms

Mostly appear with a mild to moderate degree of an allergic reaction, cause discomfort in the patient, but do not lead to death:

• catarrhal manifestations in the form of rhinitis, conjunctivitis, rhinorrhea;
• bronchospasm, shortness of breath, asthma attack, swelling of the upper respiratory tract up to complete obstruction;
• hearing loss due to swelling of the mucosa inside the Eustachian tube;
• multiform skin rashes, such as urticaria, eczema, contact allergic dermatitis (located in places with delicate skin - stomach, inguinal region, ulnar fossa); usually symmetrical.

Common symptoms

Associated with the complex effects of allergen on the body:

• headache, weakness, lethargy, drowsiness;
• nausea, vomiting, dyspeptic disorders in the form of diarrhea or constipation, cramping pains in the abdomen;
• heart rhythm disturbance, pressure drop, fainting, collapse, shock.

Anaphylactic shock

It is the most severe manifestation of what allergic reactions are capable of. Anaphylactic shock begins abruptly, within the first minutes after contact with the antigen. First of all, a vigorous local reaction to a medicine, food or bite should alert the doctor. This can be excessive pain, reactive edema, intolerable itching or a sharp drop in pressure. If the allergen is food, then everything can begin with vomiting and swelling of the mouth, larynx or pharynx.

The second stage is the reflex spasm of the bronchi and the closure of the lumen of the respiratory tract, up to a stop of breathing. Hypoxia builds up, lips and limbs turn blue, the patient faints, faints, or plunges into a coma. Without surgical intervention of a medical worker, a person dies very quickly without regaining consciousness.

Urgent Care

In order to prevent the spread of antigen throughout the body, a tourniquet is applied above the site of allergen injection (if possible) and a half cube of a 0.1% adrenaline solution is injected urgently (subcutaneously or intravenously). And they add Prednisone at the rate of 5 mg per kilogram of patient’s weight to the same vein in order to slow down the systemic reaction. If these measures do not help, and the person continues to suffocate, it is necessary to intubate the trachea and begin artificial ventilation of the lungs with an Ambu bag or with a ventilator. It so happens that it is impossible to insert a breathing tube, then a decision is made on kotikotomy or tracheotomy. This will provide oxygen access and save the patient's life.

Features of the introduction of drugs

All this time, while urgent measures are being taken, one can continue to administer adrenaline to a total dose of two milliliters. But do not get involved in it, since an overdose can worsen the condition and aggravate the anaphylactic reaction. In order to relieve bronchospasm (if after administering adrenaline it didn’t pass by itself), you can inject twenty milliliters of Eufillin intravenously (slowly) into the patient.

If there is no prednisone, it can be replaced with shock doses of other glucocorticoids, for example, enter 500 milliliters of Metiprednisolone or the contents of five Dexamethasone ampoules. Smaller doses will be ineffective.

Prevention

Anaphylactic reactions are easier to prevent than to treat. To this end, possible contact with the allergen should be avoided if it is known to humans, and it is imperative to report similar reactions to medical personnel before administering drugs, surgical interventions, or physiotherapeutic procedures. In addition, allergy sufferers with experience need to carry a syringe pen with adrenaline and a nebulizer with a short-acting bronchodilator. This will greatly accelerate the provision of medical care in the event of an attack and can save a person's life.