Abstract
The bronchial vasculature derives oxygenated blood from the systemic circulatory system and serves as the principal vascular supply of the conducting (nonrespiratory) portions of the airways. Its predominant function is to supply nutrition to the tracheal and bronchial wall, large pulmonary blood vessels, some hilar structures, including lymph nodes, lung parenchyma, and visceral pleura. In addition, the bronchial circulation has important roles in airway heat and water exchange with the environment, the clearance of locally released biologically active substances in the airway wall, and possibly the regulation of airway caliber in the lung periphery. Furthermore, the bronchial circulation functions as the conduit for inflammatory cell recruitment in inflammatory airway diseases such as bronchial asthma and chronic bronchitis, and participates in the clearance of inhaled drugs from and the distribution of systemic drugs to the airway. For decades, the technical challenges of assessing the bronchial circulation in vivo have limited the amount of information on the bronchovascular components of airway diseases. Thus, bronchial blood flow measurements have been the focus of researchers only, and several techniques have been used. Because of the availability of recent noninvasive methods to measure blood flow in the airway mucosa, a better understanding of the bronchial circulatory system’s functional and pathophysiological importance is slowly emerging.
