Defining and classifying airway malacia
Airway malacia was defined as greater than 25% expiratory reduction in
the cross-sectional luminal area during quiet respiration on the visual
inspection at bronchoscopy 4. Lower airway malacia was
classified as TM, if the collapsibility was located on trachea, or BM,
if the collapsibility was restricted to one or both of the mainstem
bronchi and/or their divisions at the lobar or segmental level. When at
least one of the bronchi affected with trachea, the condition was called
TBM 1. In cases in where TBM didn’t exist, the malacia
was defined as isolated TM or isolated BM. The localization and severity
of TM were assessed with bronchoscopy. Trachea was divided into three
regions and classified as upper (from the cricoid to the thoracic
inlet), middle (from the thoracic inlet to the mid portion to the
intrathoracic trachea) and lower (from the middle of the intrathoracic
trachea to the carina) trachea 1. The severity of TM
was described as mild (25 – 50% reduction), moderate (50 – 90%
reduction) and severe (>90% reduction). The causes of
airway malacias were classified according to ERS guideline1.