Therapeutic measures in case of anaphylactic shock are aimed at the prompt elimination of impaired function of vital organs and body systems. First of all, it is necessary to eliminate contact with the allergen (stop the administration of a vaccine, drug or radiopaque substance, remove the sting of a wasp, etc.), if necessary, limit the venous outflow by applying a tourniquet on a limb above the site of drug administration or stinging insects, and crush this place with a solution of adrenaline and apply cold.
It is necessary to restore the airway patency (duct insertion, urgent tracheal intubation or tracheotomy), to ensure the supply of pure oxygen to the lungs.
Sympathomimetic (adrenaline) is administered subcutaneously again, followed by intravenous drip administration to improve the condition. In severe anaphylactic shock, dopamine is administered intravenously at an individually adjusted dose.
The emergency care scheme includes glucocorticoids (prednisone, dexamethasone, betamethasone), infusion therapy is carried out to replenish the circulating blood volume, eliminate hemoconcentration and restore an acceptable level of blood pressure. Symptomatic treatment includes the use of antihistamines, bronchodilators, diuretics (according to strict indications and after stabilization of blood pressure).
Inpatient treatment of patients with anaphylactic shock is carried out for 7-10 days. Further monitoring is necessary to identify possible complications (late allergic reactions, myocarditis, glomerulonephritis, etc.) and their timely treatment.
Anaphylactic shock (anaphylaxis) is a severe systemic allergic reaction of an immediate type that develops upon contact with foreign substances-antigens (drugs, serums, X-ray contrast agents, food products, snake bites and insects), which is accompanied by marked disorders of blood circulation and functions of organs and organs. systems.
Anaphylactic shock develops in about one in 50,000 people, and the number of cases of this systemic allergic reaction is increasing every year. Thus, in the United States of America every year more than 80 thousand cases of anaphylactic reactions are recorded, and the risk of at least one episode of anaphylaxis in life exists in 20-40 million people in the United States. According to statistics, in about 20% of cases the cause of anaphylactic shock is the use of drugs. Anaphylaxis is often fatal.
Causes of anaphylactic shock
An allergen that leads to the development of an anaphylactic reaction can be any substance that enters the human body. Anaphylactic reactions often develop in the presence of a hereditary predisposition (there is an increase in the reactivity of the immune system – both cellular and humoral).
The most common causes of anaphylactic shock are:
- The introduction of drugs. These are antibacterial (antibiotics and sulfonamides), hormonal agents (insulin, adrenocorticotropic hormone, corticotropin and progesterone), enzyme preparations, anesthetics, heterologous serums and vaccines. Hyperreaction of the immune system may develop on the introduction of radiopaque drugs used in instrumental studies.
- Bites and stings. Another causative factor in the occurrence of anaphylactic shock is snake and insect bites (bees, bumblebees, hornets, ants). In 20-40% of cases of bee sting, beekeepers become victims of anaphylaxis.
- Food allergies. Anaphylaxis often develops on food allergens (eggs, dairy products, fish and seafood, soybeans and peanuts, food additives, dyes and flavors, as well as biologics used to process fruits and vegetables). Thus, in the USA, more than 90% of cases of severe anaphylactic reactions develop into hazelnuts. In recent years, the number of cases of development of anaphylactic shock to sulfites – food additives used for a longer preservation of the product. These substances are added to beer and wine, fresh vegetables, fruits, sauces.
- Physical factors. The disease can develop when exposed to various physical factors (work associated with muscle tension, sports training, cold and heat), as well as a combination of taking certain foods (most often it is shrimp, nuts, chicken, celery, white bread) and the subsequent physical loads (work on the plot, sports, running, swimming, etc.)
- Allergy to latex. Anaphylaxis to latex products (rubber gloves, catheters, tire products, etc.) is on the increase, and cross-allergy to latex and some fruits (avocados, bananas, kiwi) are often observed
Pathogenesis of anaphylactic shock
Anaphylactic shock is an immediate generalized allergic reaction, which is caused by the interaction of the substance with antigenic properties and immunoglobulin IgE. When the allergen is re-admitted, various mediators are released (histamine, prostaglandins, chemotactic factors, leukotrienes, etc.) and numerous systemic manifestations develop on the part of the cardiovascular, respiratory systems, gastrointestinal tract, and skin.
These include vascular collapse, hypovolemia, smooth muscle contraction, bronchospasm, mucus hypersecretion, edema of various localization and other pathological changes. As a result, the volume of circulating blood decreases, blood pressure decreases, the vasomotor center is paralyzed, the stroke volume of the heart decreases, and cardiovascular insufficiency develops.
A systemic allergic reaction in anaphylactic shock is accompanied by the development of respiratory failure due to bronchospasm, congestion in the lumen of the bronchi viscous mucous discharge, the appearance of hemorrhages and atelectasis in the lung tissue, blood stagnation in the pulmonary circulation. Violations are also noted on the part of the skin, abdominal organs and small pelvis, endocrine system, brain.
Symptoms of anaphylactic shock
Clinical symptoms of anaphylactic shock depend on the individual characteristics of the patient’s body (sensitivity of the immune system to a specific allergen, age, the presence of comorbidities, etc.), the method of penetration of a substance with antigenic properties (parenteral, through the respiratory tract or the digestive tract) (heart and blood vessels, respiratory tract, skin). In this case, the characteristic symptoms may develop as lightning (during parenteral administration of the drug), and 2-4 hours after meeting with the allergen.
Characteristic disorders of the cardiovascular system are characteristic of anaphylaxis: a decrease in blood pressure with the appearance of dizziness, weakness, fainting, arrhythmias (tachycardia, extrasystole, atrial fibrillation, etc.), the development of vascular collapse, myocardial infarction (pain behind the breast wall fear of death, hypotension).
Respiratory symptoms of anaphylactic shock are the appearance of severe shortness of breath, rhinorrhea, dysphonia, wheezing, bronchospasm, and asphyxia. Neuropsychiatric disorders are characterized by severe headache, psychomotor agitation, a sense of fear, anxiety, and convulsive syndrome. Dysfunction of the pelvic organs (involuntary urination and defecation) may occur. Skin symptoms of anaphylaxis – the appearance of erythema, urticaria, angioedema.
The clinical picture will differ depending on the severity of anaphylaxis.
There are 4 degrees of severity:
- When I degree of shock violations are minor, blood pressure (BP) is reduced by 20-40 mm Hg. Art. Consciousness is not disturbed, worried about dry throat, cough, chest pain, feeling hot, general anxiety, there may be a skin rash.
- For grade II anaphylactic shock, more pronounced disorders are characteristic. In this case, systolic blood pressure drops to 60-80, and diastolic – up to 40 mm Hg. Disturbed by a feeling of fear, general weakness, dizziness, symptoms of rhinoconjunctivitis, skin rash with itching, angioedema, difficulty in swallowing and talking, pain in the abdomen and lower back, heaviness in the chest, shortness of breath at rest. Often there is repeated vomiting, control of the process of urination and defecation is disturbed.
- The third degree of shock is manifested by a decrease in systolic blood pressure to 40-60 mm Hg. Art., and diastolic – to 0. There is a loss of consciousness, the pupils dilate, the skin is cold, sticky, the pulse becomes filiform, develops convulsive syndrome.
- IV degree of anaphylaxis develops with lightning speed. In this case, the patient is unconscious, blood pressure and pulse are not determined, there is no cardiac activity and breathing. Urgent resuscitation is required to save the patient’s life.
When leaving the shock, the patient remains weak, lethargic, lethargy, fever, myalgia, arthralgia, shortness of breath, pain in the heart. There may be nausea, vomiting, pain throughout the abdomen.
After relief of acute manifestations of anaphylactic shock (during the first 2-4 weeks), complications such as bronchial asthma and recurrent urticaria, allergic myocarditis, hepatitis, glomerulonephritis, systemic lupus erythematosus, periarteritis nodosa, etc.
Diagnosis anaphylactic shock
The diagnosis of anaphylactic shock is established mainly on the basis of clinical symptoms, since there is no time left for detailed anamnestic data collection, laboratory tests and allergy tests. Only taking into account the circumstances during which anaphylaxis occurred – parenteral administration of the drug, a snake bite, eating a certain product, etc., can help.
During the examination, the general condition of the patient, the function of the main organs and systems (cardiovascular, respiratory, nervous and endocrine) are assessed. Already a visual examination of a patient with anaphylactic shock can determine clarity of consciousness, the presence of a pupillary reflex, the depth and frequency of respiration, the condition of the skin, maintaining control over the function of urination and defecation, the presence or absence of vomiting, and convulsive syndrome.
Next, the presence and qualitative characteristics of the pulse on the peripheral and main arteries, the level of blood pressure, and auscultatory data when listening to heart and breathing sounds above the lungs are determined.
After providing emergency care to the patient with anaphylactic shock and eliminating the immediate threat to life, laboratory and instrumental studies are carried out to clarify the diagnosis and exclude other diseases with similar symptoms:
- Laboratory tests. When conducting a laboratory clinical examination, a clinical blood test is performed (leukocytosis is often detected, an increase in the number of erythrocytes, neutrophils, eosinophils), respiratory and metabolic acidosis is measured (measured by pH, partial pressure of carbon dioxide and oxygen in the blood), electrolyte balance is measured, and indicators blood coagulation systems, etc.
- Allergological examination. In anaphylactic shock, tryptase and IL-5 are determined, the level of general and specific immunoglobulin E, histamine, and after arresting the acute manifestations of anaphylaxis – the detection of allergens using skin tests and laboratory tests.
- Instrumental diagnostics. On the electrocardiogram, signs of overloading of the right heart, myocardial ischemia, tachycardia, and arrhythmia are determined. On the radiograph of the chest can be signs of emphysema. In the acute period of anaphylactic shock and for 7-10 days, blood pressure, heart rate and respiration, ECG are monitored. If necessary, conduct pulse oximetry, capnometry and capnography, determining the arterial and central venous pressure by an invasive method.
Differential diagnostics is carried out with other conditions that are accompanied by a pronounced decrease in blood pressure, impaired consciousness, respiration and cardiac activity: with cardiogenic and septic shock, myocardial infarction and acute cardiovascular insufficiency of various genesis, pulmonary thromboembolism, syncopal states and epileptic syndrome, hypogyne, pulmonary thromboembolism, syncopal states and epileptic syndrome, hypognema, hypometic pulmonary artery disease, syncopal states and epileptic syndrome, hypoglymicis, hypotension acute poisoning, etc.
Anaphylactic shock should be distinguished from similar in manifestations of anaphylactoid reactions that develop already at the first meeting with the allergen and which do not involve immune mechanisms (antigen-antibody interaction).
Sometimes differential diagnosis with other diseases is difficult, especially in situations where there are several causal factors that caused the development of a shock (a combination of different types of shock and the addition of anaphylaxis to them in response to the introduction of any medication).
Prognosis and prevention of anaphylactic shock
The prognosis for anaphylactic shock depends on the timeliness of adequate therapeutic measures and the general condition of the patient, the presence of concomitant diseases. Patients who have had an anaphylaxis episode should be registered with the local allergist. They are issued to be issued allergological passport with notes about the factors causing the phenomenon of anaphylactic shock.
To prevent such a state, contact with such substances should be excluded.