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Peculiarities of pulmonary mechanics and gas exchange in asthma patients with different types of reaction to cold and osmotic stimuli

Introduction. The airway constriction due to bronchospasm can lead to more pronounced disturbances of regional ventilation and limit gas exchange in patients with bronchial asthma. Aim. To study the features of the mechanics of respiration and gas exchange in asthma patients with different types of reaction to cold and hypoosmolar stimuli. Materials and methods. The design involved a comprehensive four-day examination of 367 patients with persistent asthma with an analysis of the baseline spirometric parameters and their dynamics for the administration of a β 2 -agonist, after bronchoprovocation testing – isocapnic hyperventilation with cold air (-20oC) (IHCA), inhalation of ultrasonically nebulized distilled water (IDW). Lung was assessed using bodyplethysmography, capnovolumetry, measurements of the diffusion capacity of the lungs. Results. A comparative analysis was carried out after the distribution of patients into groups according to the types of response to the IHCA and IDW samples. Group 1 included patients with airway hyperresponsiveness to both stimuli (cold and osmotic); group 2 – patients with cold airway hyperresponsiveness, group 3 – patients with osmotic airway hyperresponsiveness, group 4 – patients who did not respond to both stimuli. The patients of group 1 controlled asthma symptoms to a lesser extent, smoked more often, had lower baseline values of bronchial patency indices and a high increase in FEV1 per inhalation of a short-acting β 2 -agonist; in 71% of patients, increased bronchial resistance was registered, which in one third was combined with high residual volume. In these patients, a close relationship was found between the capnovolumetry indicator (dMM/dV 3 ) and the diffusion capacity of the lungs (TL CO ) (Rs=0.42; p˂0.05), as well as with FEV 1 (Rs=-0.23; p˂0.05) and MOC 25-75 (Rs=-0.24; p˂0.05). Conclusion. Asthma patients with combined airway hyperresponsiveness to cold and osmotic stimuli are characterized by more significant disturbances in the mechanics of respiration and gas exchange, affecting both the peripheral and central parts of the respiratory tract.