Small airways dysfunction and the state of lung function in mild asthma

Aim . To assess the state of pulmonary function in patients with mild asthma, depending on the state of the small airways. Materials and methods . The study included 114 patients with partially controlled mild asthma (average age 45.12±2.18 years). Depending on the state of the small airways, patients were divided into two groups: first group ‒ 94 patients without small airways dysfunction (SAD) (82%); second group – 20 patients with SAD (18%). The control group consisted of 25 healthy volunteers. Results . It was found that in the group of asthma patients with SAD, in comparison with healthy, a decrease in almost all spirometry indicators was detected, and generalized bronchial obstruction was diagnosed in 55% of cases. Characteristic of asthma patients with SAD was a decrease in the vital capacity of the lungs (VC) by 16% (p<0.001) and the inspiratory capacity (IC) – by 14% (p=0.005) in comparison with patients without SAD. These indicators are used to determine the total lung capacity (TLC=VC+RV and TLC=IC+FRC), where RV is the residual volume, and FRC is the functional residual capacity. It follows that in the case of normal values of TLC, according to spirometry data, with a decrease in VC, it is possible to indirectly judge an increase in RV and the formation of “air traps”, with a decrease in IC – an increase in FRC and the development of hyperinflation of the lungs. Conclusion . The study showed that in patients with mild asthma, SAD was diagnosed in 18% of cases, and it makes a significant contribution to changes in lung function. In mild asthma, SAD is accompanied by generalized bronchial obstruction in 55% of cases. With a decrease in VC and IC according to spirometry data in patients with mild asthma, it is possible to indirectly judge the formation of “air traps”, the development of lung hyperinflation, and consequently, the small airways dysfunction.