The bronchial vasculature is the systemic arterial blood supply to the lung. Although small relative to the pulmonary blood flow, the bronchial vasculature serves important functions and is modified in a variety of pulmonary and airway diseases.Congestion of the bronchial vasculature may narrow the airway lumen in inflammatory airway diseases, and formation of new bronchial vessels (angiogenesis) is implicated in the pathology of a variety of chronic inflammatory, infectious and ischaemic pulmonary diseases. The remarkable ability of the bronchial vasculature to remodel has implications for disease pathogenesis.The contributions of the bronchial vasculature to the pathogenesis of pulmonary disease are reviewed in this article. Eur Respir J 1997; 10: 1173-1180. The bronchial circulation is ideally situated to play an important role in lung defence and in the pathogenesis of a number of airway diseases. The bronchial microvasculature provides nutrient blood flow to the airway epithelium and is important for proper functioning of the mucociliary escalator. Bronchial blood flow is responsive to changes in neural and humoral stimuli and plays a role in conditioning of inspired air. The focus of this review is the potential involvement of the bronchial vasculature in contributing to the pathogenesis of a variety of airway diseases. In particular, we have focused on the possibility of airway narrowing as a consequence of bronchial vascular congestion, and the remarkable proliferative capacity of the bronchial vessels in response to a variety of pulmonary diseases. Bronchial vascular congestionHyperaemia of the bronchial vasculature is often included in descriptions of the pathology of asthma. An example of hyperaemia of the bronchial vasculature is shown in figure 1. This photomicrograph shows a crosssection of a human airway from a patient who died of asthma. The apparent increase in the size and number of vessels inside and outside the smooth muscle layer is clearly visible, suggesting that vascular dilation and proliferation (angiogenesis) could be important components of the airway wall remodelling in asthmatic patients. The airway vasculature is of considerable interest in asthma because it can contribute to the excessive airway narrowing, which is characteristic of this disease. A diagram of an airway ( fig. 2) illustrates the two bronchial vascular plexuses: the peribronchial plexus, located in the adventitial space between the muscle and the surrounding lung parenchyma; and the submucosal vascular plexus, located beneath the epithelial layer. Dilation, exudation or transudation from these vessels could contribute to the excessive airway narrowing observed in asthma. Relaxation of the bronchial vascular smooth muscle and/or an increase in the intravascular pressure will lead to congestion of these vessels. This bronchial vascular congestion could result in a reduction in the area of the airway lumen and/or an increase in the outer diameter of the airway. The latter effect could uncouple the airway smoo...

The use of spiral computed tomography (CT) for the diagnosis of pulmonary embolism has been compared to angiography, the current gold standard. However, the accuracy of pulmonary angiography has never been evaluated against an independent gold standard. The aim of this study was to compare contrast-enhanced spiral CT to pulmonary angiography for the detection of subsegmental-sized pulmonary emboli by using a methacrylate cast of porcine pulmonary vessels as an independent gold standard. We studied 16 anesthetized, juvenile pigs and injected colored methacrylate beads (3.8 mm, small; 4.2 mm, large) via the jugular vein. After embolization spiral CT (3 mm and 1 mm collimation), and pulmonary angiography were performed. Pigs were killed and the pulmonary arterial tree was cast using methacrylate. Spiral CT and angiography were interpreted independently by two radiologists. Sensitivity and 95% confidence intervals for 3 mm and 1 mm collimation CT and angiography, respectively, were: 82% (73 to 88%), 87% (79 to 93%), 87% (79 to 93%) (p = 0.42). Positive predictive values and 95% confidence intervals for 3 mm and 1 mm collimation CT and angiography, respectively, were: 94% (86 to 94%), 81% (73 to 88%), and 88% (80 to 93%). There was no difference between spiral CT and angiography for detection of subsegmental-sized pulmonary emboli. We conclude that spiral CT is comparable to angiography for detection of pulmonary emboli.

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