Hypersensitive pneumonitis in children is an immuno–inflammatory pathology caused by the inhalation of small organic particles that are antigens, and accompanied by a violation of the structure of the alveolar and interstitial lung tissue. The clinic includes an unproductive cough, shortness of breath, an increase in body temperature against the background of severe inflammation. Diagnosis involves chest X-rays, bacteriological examination of sputum, general clinical tests, requires consultation with a pulmonologist and allergist. Therapy consists in eliminating contact with the allergen, reducing the severity of symptoms by taking anti-inflammatory drugs.
J67 Hypersensitive pneumonitis caused by organic dust
Hypersensitive pneumonitis in children is the name of a group of allergic lung diseases formed against the background of constant and intense inhalations of a certain irritant. It is an acute or chronic inflammatory process affecting the alveoli and interstitium. Functional disorders are nonspecific and similar to those in 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. Pathology affects girls and boys to the same extent.
The etiological factor is small inhaled particles entering the lower parts of the respiratory system. It has been proven that organic and inorganic dust with a diameter of up to 5 microns can freely enter the alveoli and cause an allergic inflammatory reaction. Repeated inhalation of antigens plays an important role in the mechanism of development. Allergens include microscopic organisms and products of their metabolism (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), inhalation or powder medications (hormones, antibacterial drugs).
Due to the disease, specific changes in the lungs are judged. In a child, according to the generally accepted classification of allergic alveolitis, the so–called “lung of pigeon breeders” or “lung of budgie lovers” is most often formed, since contact with birds is most likely – parrots are brought as pets. Other types of disease (suberosis, malt lung) are more characteristic of adult patients employed in agriculture and industrial enterprises, but their appearance in children is also not excluded.
The main condition for the development of inhalation pneumopathy is frequent inhalation of the allergen in sufficient concentration. The influence of endogenous factors (heredity, features of 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 types (according to the Gell-Coombs classification).
The third type is an immunocomplex variant of hypersensitivity reaction. It is based on the production of immunoglobulins M and G. These protein elements come into direct contact with allergens. As a result of the reaction of the antibody + antigen compound, an immune complex is formed that circulates 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 secrete inflammatory mediators, release histamine.
At this point, the fourth type of allergy is activated – a delayed hypersensitivity reaction, or a 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 increases, the structure of the lung tissue is disrupted.
In pediatrics, there are three clinical forms of alveolitis: acute, subacute and chronic. The 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 is noted. A little later, changes from the lungs are determined: dry cough, increasing shortness of breath. After the termination of contact with the stimulus, the condition stabilizes, the symptoms regress, 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 expressed to a lesser extent, of all the complaints there are only a slight cough and shortness of breath. There are no signs of deterioration of the general condition in the form of increased body temperature, chills and malaise.
The chronic type of alveolitis is characterized by a productive cough with the separation of mucosal sputum, shortness of breath. Against the background of tissue hypoxia, the end phalanges of the fingers change according to the type of “drumsticks”, cyanosis of the skin appears during physical exertion. The clinical picture is complemented by increased fatigue, decreased or complete lack of appetite.
The progression of the allergic inflammatory process, the formation of interstitial fibrosis and the gradual disruption of blood supply to tissues leads to stagnation of blood in the small circle of circulation, pulmonary hypertension. Such changes result in the development of a chronic pulmonary heart (CPH) and respiratory failure. CPH is a consequence of hemodynamic disorders, in which progressive circulatory insufficiency is formed, the heart rhythm is disrupted, and organs suffer from oxygen starvation. Ignoring the developing symptoms does not exclude a fatal outcome.
To make an accurate diagnosis and undergo a full-fledged examination, a consultation of a pediatrician and a pediatric allergist-immunologist is required. 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:
- Evaluation of objective features. Symptoms include shortness of breath, productive or dry cough. With an acute course, the body temperature increases, chills appear. With auscultation of the lungs, crepitation is noted, more pronounced in the lower parts of the lungs, sometimes wheezing.
- Laboratory data. In the general blood test, the number of neutrophils increases, the ESR increases. Biochemical immunological examination of venous blood reveals high concentrations of IgG and IgM, C-reactive protein.
- Functional tests. In the course of spirometry, a decrease in pulmonary volumes, the speed of forced exhalation is revealed. Functional tests indicate a decrease in tissue elasticity, a violation of the function of gas exchange. FER is possible only for children over 5 years old.
- Radiation diagnostics. Radiography of the chest area diagnoses the darkening of the pulmonary fields, with a chronic process, multiple small focal shadows are determined. According to the CT of the lungs, a mesh rearrangement of the pulmonary pattern is detected, small focal shadows are visible.
Differential diagnosis is carried out with malignant neoplasms (carcinoma, lymphogranulomatosis), fibrosing alveolitis of non-allergic nature, granulomatoses, systemic pathologies: vasculitis, nodular periarteritis, Wegener’s granulomatosis. Sometimes, with an uncertain clinical picture and unclear examination results, a lung biopsy is performed.
Treatment of hypersensitive pneumonitis in children
To eliminate the cough attack, contact with the irritating agent should be stopped, after which inhaled hormone therapy should be started immediately. The only effective drugs suitable for eliminating the chronic form of allergic alveolitis are glucocorticosteroids. Their dose is selected taking into account the age of the child and the severity of the disease.
To increase the patency of the respiratory tract and eliminate tissue hypoxia, treatment is supplemented with oxygen therapy, beta-2-adrenomimetics, anticholinergics, methylxanthines. When a secondary infection is attached, antibiotics or antiviral medications are prescribed. Oral antihistamines are not used because of the low therapeutic effect.
Prognosis and prevention
Prevention of inhalation pneumopathy consists in limiting contact with the antigen and in 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, severity of pathology. In acute and subacute forms, symptoms disappear without a trace, taking medications is not required. With a chronic type of the disease, a complete cure is unlikely, the inflammation progresses, however, with the help of medications, it is possible to achieve a long-term remission.