Dynamic obstruction of the central airways: tracheobronchomalacia and excessive dynamic airway collapse
Abstract
The central airways change diameter during inspiration and expiration. This dynamic variability result from changes in intrathoracic pressure, but an important role is also played by airway compliance.
Some diseases affect the airway structure to such extent that they are prone to collapse. This may be important especially during exaggerated respiratory effort, when the central airways may collapse completely, causing a dynamic obstruction and an increase in resistance and work of breathing.
A collapse that exceeds fifty percent of the maximum airway diameter is considered to be pathological. This is referred to as malacia or excessive dynamic airway collapse and can be diagnosed in both pediatric and adult populations; in adults, it is often seen in combination with chronic obstructive pulmonary disease or bronchial asthma.
Among a variety of symptoms, the most frequent are dyspnea, cough and recurrent respiratory infection. The main focus of this article is tracheobronchomalacia and excessive dynamic airway collapse in the adult population; it reviews recent knowledge of its etiology, diagnosis and treatment.