The role of the tracheobronchial circulation in aerosol clearance.

In summary, the airway is provided with a dense vascular network on either side of the airway smooth muscle throughout the bronchial tree. It is likely that this circulation can provide an important clearance function for the removal of smooth muscle agonists. However its supportive role for other airway structures such as ciliated cells and mucus glands has not been studied. For this reason it is unclear whether this circulation plays a significant part in maintaining mucociliary clearance. Consequently the capacity of the airway circulation to influence the clearance of soluble and insoluble particles remains ill-defined and requires investigation at a fundamental level.