SUBCLINICAL SMALL AIRWAY DYSFUNCTION IN URBAN ADOLESCENTS WITH NORMAL SPIROMETRY: A PILOT EPIDEMIOLOGICAL ANALYSIS

Abstract

This study evaluated the functional state of small airways among adolescents living in an urban environment, with particular attention to the detection of subclinical changes despite normal conventional spirometric parameters. A total of 30 participants aged 15–17 years underwent spirometry, including assessment of FVC, FEV₁, FEV₁/FVC, PEF, and FEF25–75 indices. The results demonstrated that although the primary spirometric parameters remained within normal limits, the mean value of FEF25–75 was 66.7 ± 21.5%, indicating significant functional heterogeneity of the small airways. In 70% of participants, FEF25–75 values were reduced or borderline, suggesting early-stage small airway impairment. When integrated with contemporary scientific evidence, these findings confirm the high diagnostic sensitivity of FEF25–75 in assessing small airway function and highlight the necessity of early detection of environmentally associated respiratory alterations in urban populations.