Assessment of alveolar ventilation in patients with asthma, COPD and their combination

Disturbance of alveolar ventilation in asthma, COPD and their combination (asthma-COPD-overlap syndrome — ACOS) lead to pulmonary insufficiency and disability of patients. The aim was to assess the alveolar ventilation in patients with asthma, COPD and their combination. Methods. The study involved 34 patients with asthma, 17 with COPD, 140 with ACOS and 35 healthy persons who underwent capnometry. Results. In asthma, COPD and ACOS, on average there is a satisfactory compensation of pulmonary ventilation disorders, which may be one of the reasons for the late patients recurrence for medical care. The increase of bronchial obstruction is accompanied by the development of violations of alveolar ventilation, when there is an increase in the volume of the «dead» space from 282.8±10.4 ml at grade 2 to 361.5±24.9 ml at 3 grade and its proportion in the respiratory volume from 30.9±0.6 to 34.9±0.8%, respectively (p<0.05). In the formation of hyperinflation of the lungs, the risk of alveolar ventilation disorders increases significantly by half (odds ratio is 1.94 with a 95% confidence interval of 1.04 to 3.62). Conclusions. Statistically significant violations of alveolar ventilation in patients with ACOS are formed during the transition from 2 to 3 grades of bronchial obstruction. Complex evaluation of the respiratory function and capnometry allows to separate the functional subphenotypes of the disease, which pathophysiologically repeat the natural course of the primary pathology.