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 the French scientist, Nobel Prize winner in medicine, physiologist Charles Richet. Then Alexander Mikhailovich Bezredko picked up his idea in domestic medicine, he improved the methods of administering drugs to patients with a history of allergies. Later, emergency protocols were developed for such patients, and the number of deaths decreased. However, despite modern medicines, the death 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 is re-encountered. There are several types of allergic reactions:
- immediate or anaphylactic;
- cytotoxic (antibodies cross-react with body tissues);
- immunocomplex (vascular damage by activated immunecomplexes);
- delayed, or cell-dependent.
Anaphylactic reactions are a manifestation of an allergic reaction of the first type, that is, immediate.
In addition, anaphylactoid reactions are also isolated in clinical practice, 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.
Reasons
Initially, anaphylactic allergic reactions occurred when a poisonous substance entered the human body. An example is the bites of poisonous insects and reptiles. But in the modern world, the body can react incorrectly even to familiar, banal things:
- Food - honey, milk, nuts, eggs, seafood, chocolate, citrus.
- Medicines - hormones, contrast agents, vaccines and serums, anesthetics.
- Plants and animals - flower pollen, fungus, animal fur, dust mites.
- Ambient temperature - cold/hot.
- Increased chance of allergies in people with asthma, vasomotor rhinitis, eczema.
This is just a short, very generalized list of things that can cause allergies in the average person. In addition, if such reactions are observed in relatives of the first line of kinship, 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 meeting with the antigen, the body produces immunoglobulins M, and at the second - G. But sometimes this process goes astray. The anaphylactic type of reaction appears 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 is repeatedly exposed to the antigen, then IgE activate basophils and release inflammatory mediators such as histamine, cytokines, interleukins, prostaglandins and leukotrienes. In large quantities, they systemically affect the tissues of the body, causing edema, vasodilation, contraction of smooth muscles in the walls of hollow organs, respiratory disorders, and increased secretion of glands. An area of inflammation is formed at the site of penetration of the allergen. This is the immediate hypersensitivity phase.
But the development of an anaphylactic reaction has a second period, or phase, called delayed hypersensitivity. To form a focus of inflammation, cells enter there by chemotaxis - lymphocytes, neutrophils, eosinophils, macrophages. They contain substances in the cytoplasm that are necessary to fight a foreign agent, but instead they destroy the body's own tissues, and connective tissue is formed instead. Usually a slow responsecomes six hours after 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 signs help to quickly assess the patient's condition and provide him with the necessary assistance.
- Mild anaphylactic reactions do not pose a threat to human life. Subjectively, patients describe them as a feeling of paresthesia - tingling or warmth 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 come and go within a day.
- Moderate severity manifests itself 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 states, Quincke's edema, urticaria are possible. There may be general intoxication manifestations, such as nausea, vomiting, headache, fever. In some cases, erythema, severe itching, and nervous excitement appear.
- Severe anaphylactic reactions begin acutely and tend to be mild at first. Then, after a few minutes, the second stage begins with bronchospasm, swelling of the upper respiratory tract and bronchi, and respiratory failure. Then cyanosis appears, there may be respiratory arrest. The next step is the generalization of symptoms. The mucous membrane swells not only in the respiratory organs, but also in the digestive tract. This leads to violationperistalsis, vomiting, diarrhea and abdominal pain. On the part of the nervous system, epileptic seizures, impaired innervation of the pelvic organs can occur. Systemic expansion of 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 rate of development of the process, they are in direct proportion: the faster, the worse the prognosis. Up to death.
Local symptoms
Mainly appear with a mild to moderate allergic reaction, cause discomfort to 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 hives, eczema, allergic contact dermatitis (located in places with delicate skin - abdomen, groin, antecubital fossa); generally symmetrical.
General symptoms
Associated with the complex effect of the allergen on the body:
- headache, weakness, lethargy, drowsiness;
- nausea, vomiting, dyspeptic disorders in the form of diarrhea or constipation, cramping pain in the abdomen;
- heart rhythm disturbance, pressure drop, fainting, collapse, shock.
Anaphylactic shock
He is the mostsevere manifestation of what allergic reactions are capable of. Anaphylactic shock begins abruptly, within the first minutes after contact with the antigen. First of all, the doctor should be alerted by a violent local reaction to a medicine, food or bite. This may be excessive pain, reactive swelling, unbearable itching, or a sharp drop in pressure. If the allergen is food, then everything can start with vomiting and swelling of the mouth, larynx or pharynx.
The second stage is a reflex spasm of the bronchi and the blocking of the airway lumen, up to respiratory arrest. Hypoxia increases, lips and limbs turn blue, the patient loses consciousness, faints or plunges into a coma. Without the prompt intervention of a medical worker, a person dies very quickly without regaining consciousness.
Emergency
In order to prevent the spread of the antigen throughout the body, a tourniquet is applied above the injection site of the allergen (if possible) and half a cube of 0.1% adrenaline solution is urgently injected (subcutaneously or intravenously). And they add there, in a vein, "Prednisolone" at the rate of 5 mg per kilogram of the patient's weight 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 start artificial ventilation of the lungs with an Ambu bag or a ventilator. It happens that it is impossible to insert a breathing tube, then a decision is made about caticotomy or tracheotomy. This will provide oxygen and save the patient's life.
Features of introductiondrugs
All this time, while urgent measures are being taken, you can continue to inject adrenaline up to a total dose of two milliliters. But do not get carried away with them, as an overdose can worsen the condition and exacerbate the anaphylactic reaction. In order to relieve bronchospasm (if after the introduction of adrenaline it did not go away on its own), you can inject twenty milliliters of "Eufillin" intravenously (slowly) into the patient.
If there is no prednisolone, it can be replaced with loading doses of other glucocorticoids, for example, enter 500 milliliters of Metyprednisolone or the contents of five ampoules of Dexamethasone. Smaller doses will be ineffective.
Prevention
Anaphylactic reactions are easier to prevent than to treat. To do this, possible contact with the allergen should be avoided if it is known to the person, and it is imperative to report such reactions to medical professionals before administering drugs, surgical interventions or physiotherapy procedures. In addition, experienced allergy sufferers need to carry an adrenaline pen and a short-acting bronchodilator nebulizer. This will greatly speed up the provision of medical care in the event of an attack and can save a person's life.
