Daily Archive 30.10.2019

Diagnosis of exogenous allergic bronchioalveolitis

There are no specific diagnostic methods for exogenous allergic bronchioloalveolitis. The diagnosis is based on the following criteria: typical allergic history (contact with organic dust); dynamics of clinical signs; positive allergic diagnostic tests intradermally for the corresponding antigens such as GNT and HRT; detection of precipitating antibodies related to immunoglobulins G; lack of eosinophilia of peripheral blood and sputum; radiological changes; restrictive ventilation disorders; positive RBTL and RTML; inhibition of macrophage migration under the influence of a specific antigen; HRT, GNT or a double bronchospastic reaction or crepitation over the lungs after allergological diagnostic tests of provocative inhalation with extracts of specific antigens.

X-ray data in the acute phase of the disease may be normal. As the disease develops, bilateral middle and lower lobe focal shadows appear with a tendency to merge and diffuse. Comparison of radiographs with lung biopsy data reveals that focal shadows correspond to granulomas and interstitial infiltrates. In acute cases, the radiograph of the lungs normalizes within 10-20 days after eliminating contact with the antigen. For the chronic form of exogenous allergic bronchioloalveolitis, fibrosis is characteristic; a cell lung pattern may develop.

Functional disorders of the respiratory system consist in restrictive ventilation failure, a decrease in the diffusion capacity of the lungs and static pulmonary volumes in the absence of airway obstruction. In severe cases, hypoxemia and hypercapnia may occur. In the later stages, a third of patients develop irreversible airway obstruction with a change in the relationship between ventilation and blood flow. In the acute phase of exogenous allergic bronchioalveolitis with fever, leukocytosis of up to (15-20) 109 leukocytes per 1 liter with a neutrophilic shift is observed, eosinophilia, hypergammaglobulinemia are sometimes noted; the level of immunoglobulins is increased, with the exception of immunoglobulin E.
Positive delayed and immediate skin tests for the introduction of antigen, antibodies related to immunoglobulin E, positive cell-type reactions (RBTL and RTML) with specific antigens are observed not only in patients with exogenous allergic bronchioalveolitis, but also in a certain contingent of people in contact with the same antigens, but not having symptoms of the disease. Cell-type reactions are of great diagnostic value compared to the detection of precipitating antibodies. RBTL remains positive for many months, while the precipitation reaction quickly becomes negative after cessation of contact with the antigen. Conducting provocative inhalation tests with specific antigens is unsafe, but in some cases it is possible. The diagnosis is helped by a study of bronchial lavage water, in which an increased number of lymphocytes is detected (the larger the more acute the form of the disease) – from 35 to 90% (average 50-60%). These results differ from those obtained for persons also exposed to organic dust, but without signs of disease. Despite the presence of specific precnpitins in the latter, the cellular composition of lavage fluid remains normal, which coincides with the absence of clinical signs of the disease. Lavage fluid lymphocytosis has not only diagnostic, but also prognostic value, as it quickly disappears with effective treatment or a spontaneous favorable course and is again detected during exacerbation.

Differential diagnosis of exogenous allergic bronchioloalveolitis

Differential diagnosis of the acute form is carried out with acute viral infectious diseases (influenza, etc.), acute pneumonia, allergic bronchopulmonary aspergillosis, chronic – with other diffuse lung lesions with progressive pulmonary and general symptoms.

Treatment of exogenous allergic bronchioloalveolitis

The main event is the elimination of the etiological factor. In particular, if the cause of the disease is pituitary powder (in patients with diabetes insipidus), then when switching to synthetic vasopressin, the symptoms of the disease disappear. If the disease progresses after removal of the antigen, then pharmacological therapy is necessary. The main treatment is glucocorticosteroid drugs, which are most effective in the acute form of exogenous allergic bronchioalveolitis, with a chronic effect is insufficient. The duration of glucocorticosteroid therapy is determined by clinical and laboratory data. GNT during provocative inhalation tests with specific antigens is prevented by the intal, but its effectiveness in conditions of professional contact with organic dust has not been proved. Antihistamines and bronchodilators are not effective. In cases of infection, antibiotics are prescribed, with appropriate indications, antimycotic drugs.
Prevention consists in storing organic materials under conditions that exclude their moisture, heating and decay.