Fig. 1

Phenotypes of tracheobronchomalacia (TBM) based on paired inspiratory and expiratory images and percentage of luminal reduction. (A) Normal trachea and dynamic airway collapse. (B) Excessive dynamic airway collapse and crescent type airway collapse. (C) Circunferential airway collapse and saber-sheath airway collapse. No TBM is characterized by physiological dynamic airway collapse with less than 50% luminal reduction (A) Excessive Dynamic Airway Collapse (EDAC) is defined by a cross-sectional reduction in airway area of 50% or more during dynamic expiratory maneuvers, with morphologic preservation of the anterior “C” cartilage (B) Crescent Type features presumed softening of the anterior cartilaginous wall, leading to splaying and excessive narrowing of the airway lumen by 50% or more (B) Circumferential Type involves airway collapse of 50% or more affecting both the anterior and lateral cartilaginous walls, accompanied by wall thickening (C). Saber-Sheath Type is characterized by softening of the lateral walls forming an “A” shape, with expiratory airway narrowing of 50% or greater (C) Note that the Saber-Sheath Type image provided is an example of the pathology but is not a representative image of any patient included in the study.