Etiology and risk factors
The development of acute allergic reactions is always based on prior sensitization of the organism. The triggering mechanism is repeated contact with the allergen. Rapid development of sensitization, which is particularly relevant in pediatric practice, is promoted by genetic predisposition (atopy), impaired immunological tolerance mechanisms, and prolonged exposure to a potential allergen.
Depending on the route of antigen entry, a diverse spectrum of triggers is formed:
- Enteral route: food products, chemical additives, oral medications.
- Inhalational route: house dust and mites, animal dander, mold spores, pollen, volatile chemical compounds, and insect chitin particles.
- Parenteral route: injection of vaccines and drugs, venom from biting or stinging insects.
- Contact route: exposure to cosmetics, detergents, pesticides, and photoreactive substances.
Pathogenesis and morphological changes
Angioedema is based on the classical reaginic mechanism — IgE-mediated type of hypersensitivity.
From a pathomorphological standpoint, the histological picture in angioedema is practically identical to the changes occurring in localized urticaria. There is marked local tissue edema, dilation (expansion) of the microvasculature, including arterioles and capillaries, as well as moderate perivascular infiltration by lymphocytes.
The key difference lies in the depth of the lesion: while in urticaria the process is limited to the papillary dermis, in angioedema it extends significantly deeper, totally involving the subcutaneous adipose tissue and mucous membranes.
Clinical presentation and risk zones
The disease manifests suddenly. The main symptom is the rapid development of circumscribed edema affecting body areas with the most developed and loose subcutaneous adipose tissue.
Common sites of edema:
- Facial area (eyelids, lips, nose, ears).
- Mucous membrane of the tongue.
- Distal parts of the upper and lower extremities.
- Genital area.
The most serious threat to the patient's life is isolated or combined laryngeal edema. This life-threatening condition clinically manifests as croup syndrome—acute upper airway obstruction, which leads to asphyxia without immediate intervention.
Principles of intensive care and action algorithm
When acute allergic reactions occur, emergency medical care is necessary. Basic treatment principles include a clear sequence of actions:
- Cessation of exposure. Immediate stoppage of the triggering allergen's entry into the body (stopping drug administration, removing the stinger, etc.).
- Elimination therapy. Aimed at accelerating the excretion of the antigen that has already entered the body. Ample alkaline drinking, enzyme preparations, and, when indicated, diuretics are prescribed.
- Pharmacotherapy. Drugs are administered parenterally for the fastest possible systemic effect. Glucocorticosteroids (e.g., prednisolone) and H1-histamine receptor blockers (diphenhydramine, chloropyramine, clemastine, promethazine, hydroxyzine, astemizole, terfenadine) are used.
- Airway management. When laryngeal edema develops, against the background of GCS and antihistamine administration, restoring and maintaining airway patency becomes an absolute priority.
P-E-P-A algorithm: P — Cessation of contact with the allergen, E — Elimination (excretion), P — Pharmacotherapy (parenteral GCS), A — Airway management in case of laryngeal edema.
Class and exam questions
What is the main morphological difference between angioedema and acute urticaria?
Their histological picture is identical (edema, capillary dilation, lymphocytic infiltration), but in angioedema, the pathological process extends deeper, involving the subcutaneous adipose tissue and mucous membranes.
Which complication of angioedema is the most dangerous?
Isolated or combined laryngeal edema. It clinically manifests with croup syndrome and causes acute airway obstruction, threatening the patient's life.
Through what route should medications be administered during emergency care?
Pharmacotherapy (glucocorticosteroids and H1-histamine receptor blockers) must be administered exclusively parenterally to ensure an immediate therapeutic effect.
For what purpose is ample alkaline drinking prescribed?
Alkaline drinking is a component of elimination therapy. It promotes the accelerated elimination of the allergen that has already managed to enter the patient's body.
What else to study on this topic
- Clinical picture and local manifestations of acute urticaria.
- Complications of severe urticaria (allergic myocarditis, reactive pancreatitis, arthritis).
- Systemic generalized allergic reactions: anaphylactic shock.
- Severe toxico-allergic reactions: Stevens-Johnson syndrome and Lyell's syndrome.
- Criteria for terminating intensive therapy in severe toxicoderma.
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