Prevalence of tracheobronchomalacia and excessive dynamic airway collapse in bronchial asthma of different severity

BACKGROUND Tracheobronchomalacia (TBM) is a pathologic condition in which softening of tracheal and bronchial cartilage causes the dynamic narrowing of transverse or sagittal diameters of tracheobronchial lumen; an excessive dynamic airway collapse (EDAC) may also be associated, with a substantial invagination of the posterior membrane of trachebronchial tree.The aim of this study was to assess the prevalence of both TBM and EDAC in a population of asthmatics with different degrees of disease severity compared to a reference group of subjects without any bronchial obstruction. METHODS A cohort of 202 asthmatics was investigated by means of a dynamic flexible videobronchoscopy: 74 mild persistent (MPA - age 18-68 ys; 35 males; mean FEV1 = 88.6% pred. ± 8.3 sd); 63 moderate (MA - age 21-71 ys; 30 males; mean FEV1 = 71.3% pred. ± 9.1 sd), 65 severe asthmatics (SA - age 33-70 ys; 25 males; mean FEV1 = 48.5% pred. ± 7.6 sd), and 62 non obstructed subjects (NO - age 18-71 ys; 38 males; mean FEV1 98.6% pred. ± 2.7 sd). TBM and EDAC were classified according to FEMOS classification. RESULTS TBM and EDAC were observed in only 1/62 subjects (both 1.61%) of NO group, while their prevalence was 2.70% and 6.75% in MPA group; 7.93% and 19.04% in MA group; 18.46% and 69.23% in SA group, respectively. The crude prevalence of thyroid disorders in the population was 12.9%. In particular, the prevalence of thyroid disorders was significantly higher in females than in men, but 54-fold higher in females than in men in the presence of EDAC. CONCLUSIONS 1) The prevalence of both TBM and EDAC is directly related to age, gender (females), and asthma severity; 2) EDAC is much more frequent than TBM in all asthma patients; 3) both tracheal abnormalities proved to be more represented in asthmatics with thyroid disorders, and particularly in female asthmatics with EDAC.