29.10.2020

Causes of Allergic Alveolitis in Children

Allergic alveolitis in children (inhalation pneumopathy, hypersensitive pneumonitis) is the name of a group of allergic lung diseases that are formed against the background of constant and intense inhalation of a specific stimulus. It is an acute or chronic inflammatory process affecting the alveoli and interstitium.

Functional disorders are non-specific and similar to those of other lung lesions. In children, hypersensitive pneumonitis occurs in a wide age range – from 2 to 16 years. The prevalence of the disease is about 42 cases per 100 thousand population. Girls and boys are equally affected.

Causes of Allergic Alveolitis in Children

Etiological factors are small inhalation particles that fall into the lower parts of the respiratory system. It is proved that organic and inorganic dust with a diameter of up to 5 microns can freely fall into the alveoli and cause an allergic inflammatory reaction. In the mechanism of development, a large role is played by repeated inhalation of antigens. Allergens include microscopic organisms and their metabolic products (bacteria or fungi that produce specific enzymes, protein structures, toxins), biological substances (sawdust, animal hair, bird protein), low molecular weight substances (heavy metal salts, toluene compounds), inhaled or powdered medications (hormones, antibacterial drugs).

Due to the disease, specific changes in the lungs are judged. The child, according to the generally accepted classification of allergic alveolitis, most often forms the so-called “lighter of the pigeon breeders” or “lung of lovers of undulating parrots”, since contact with birds is most likely – they start parrots as pets. Other types of disease (suberosis, malt lung) are more characteristic of adult patients employed in agriculture and at industrial enterprises, but their appearance in children is also not excluded.

Pathogenesis

The main condition for the development of inhalation pneumopathy is frequent inhalation of the allergen in sufficient concentration. The influence of endogenous factors (heredity, immunity) is not excluded, but their role is not fully understood at the moment. Allergic alveolitis refers to allergic reactions of the third and fourth type (according to the classification of Gell-Coombs).

The third type is an immunocomplex variant of the hypersensitivity reaction. It is based on the production of immunoglobulins M and G. These protein elements are in direct connection with allergens. As a result of the reaction of the compound antibody + antigen, an immune complex is formed circulating in the body. It activates the complement system, increases the permeability of small vessels, increases the number of neutrophils and macrophages in the blood. The latter emit inflammatory mediators, release histamine.

At this point, the fourth type of allergy turns on – a delayed-type hypersensitivity reaction, or T-mediated inflammatory process. Inflammatory mediators released during immunocomplex damage attract T-lymphocytes. They, in turn, secrete cytokines: interleukins, interferons, tumor necrosis factor. The inflammatory process is intensifying, the structure of the lung tissue is disturbed.

Symptoms of allergic alveolitis in children

In pediatrics, there are three clinical forms of alveolitis: acute, subacute and chronic. Clinic of acute inflammation occurs a few hours after prolonged contact with a high concentration of allergen. The onset of the disease is similar to ARVI : the child complains of chills, headaches, general malaise, fever. A little later, changes are determined by the lungs: dry cough, increasing shortness of breath. After cessation of contact with the stimulus, the state stabilizes, symptoms regress, and in rare cases antihistamines are required.

The subacute form differs in terms of improving well-being, usually it takes several weeks or a month to eliminate signs of inflammation. However, the clinical picture is less pronounced, of all complaints there is only a small cough and shortness of breath. There are no signs of deterioration of the general condition in the form of increased body temperature, chills and indisposition.

Chronic type of alveolitis is characterized by productive cough with sputum mucus, shortness of breath. On the background of tissue hypoxia in a child, the end phalanges of the fingers change according to the type of “drumsticks”; during exercise, the cyanosis of the skin appears. The clinical picture is complemented by increased fatigue, decreased or complete lack of appetite.

Complications

The progression of an allergic inflammatory process, the formation of interstitial fibrosis and the gradual disruption of the blood supply to the tissues leads to stagnation of blood in the pulmonary circulation, pulmonary hypertension . Such changes end with the development of chronic pulmonary heart disease (CPH) and respiratory failure . CPH is a consequence of hemodynamic disturbances, in which progressive circulatory failure is formed, the heart rhythm is disturbed, and organs suffer from oxygen starvation. If you ignore the developing symptoms, death is not excluded.

Diagnostics

Consultation of a pediatrician and a children’s allergist-immunologist is required to make an accurate diagnosis and undergo a complete examination . Anamnesis is collected, complaints are clarified, a general examination is carried out, including palpation, percussion and auscultation.

The diagnosis of allergic alveolitis is made on the basis of data obtained during the following examination methods:

  • Estimates of objective signs . Symptoms include shortness of breath, productive or dry cough. With acute course the body temperature increases, chills appear. Auscultation of the lungs shows crepitus, more pronounced in the lower parts of the lungs, sometimes – wheezing.
  • Laboratory data . In general, the blood count increases the number of neutrophils, the ESR increases. Biochemical immunological examination of venous blood revealed high concentrations of IgG and IgM, C-reactive protein.
  • Functional tests . During spirometry, a decrease in lung volumes and a forced expiratory rate is detected. Functional tests indicate a decrease in tissue elasticity, impaired function of gas exchange. Holding of respiratory function is possible only for children over 5 years
  • Radiation diagnosis . Radiography OGK diagnoses the darkening of the pulmonary fields, in a chronic process, multiple small focal shadows are determined. According to CT scan of the lungs , a mesh restructuring of the pulmonary pattern is detected, small focal shadows are visible.

Differential diagnostics is carried out with malignant neoplasms ( carcinoma , lymphogranulomatosis ), non-allergic fibrosing alveolitis , granulomatosis, systemic pathologies: vasculitis , periarteritis nodosa , Wegener granulomatosis . Sometimes with an uncertain clinical picture and fuzzy examination results, a lung biopsy is performed .

Treatment of allergic alveolitis in children

To eliminate a cough attack, you should stop contact with an irritating agent, and then immediately begin inhaled hormone therapy. The only effective drugs suitable for the elimination of the chronic form of allergic alveolitis are glucocorticosteroids. Their dose is selected based on the age of the child and the severity of the disease.

To increase the airway patency and eliminate tissue hypoxia, the treatment is supplemented with oxygen therapy , taking beta-2 adrenergic mimetics, anticholinergics, methylxanthines. When attaching a secondary infection, antibiotics or antiviral medications are prescribed. Oral antihistamines are not used because of the low therapeutic effect.

Prognosis and prevention

Prevention of inhaled pneumopathy is to limit contact with the antigen and the timely treatment of the disease in order to avoid the formation of a chronic inflammatory process. The prognosis depends on the speed of diagnosis, compliance with medical recommendations, the severity of the pathology. In acute and subacute form, the symptoms disappear without a trace, the medication is not required. In the chronic type of the disease, a complete cure is unlikely, inflammation progresses, however, with the help of drugs, long-term remission can be achieved.

Allergic alveolitis in children is an immuno-inflammatory pathology caused by inhalation of small organic particles that are antigens, and is accompanied by a violation of the structure of the alveolar and interstitial lung tissue. The clinic includes an unproductive cough, shortness of breath, fever on the background of severe inflammation. Diagnosis involves chest X-ray, sputum bacteriological examination, general clinical tests, requires consultation with a pulmonologist and an allergist. Therapy is to eliminate contact with the allergen, reducing the severity of symptoms by taking anti-inflammatory drugs.

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