[Physiopathology of diffuse and bullous emphysema (author's transl)]

In emphysema, structural modifications (alveolar distension with destruction of the walls and of the pulmonary capillary bed) contribute to the understanding of pathophysiological disorders, such as increase of the static pulmonary volumes, loss of elastic recoil, impairment in gas transfer. In panlobular emphysema, the simultaneous destruction of ventilatory and circulatory structures explains the absence of shunt effect. The loss of elastic recoil is the main cause of maximal expiratory flow limitation and of bronchial obstruction which is qualified as "extrinsic". For a same degree of bronchial expiratory obstruction, the disorders of gas exchange and pulmonary haemodynamics are less pronounced in emphysema (panlobular) than in chronic bronchitis. The effects of voluminous bullae associated with diffuse emphysema are difficult to study and to demonstrate. The bullae accentuate the altered elastic properties of the emphysematous lung and contribute therefore to the expiratory flow limitation. The bullae are usually neither ventilated nor perfused; a dead-space effect is thus rare, but should be investigated. The effects of compression by the bullae of the adjacent parenchyma (excepting the haemodynamic effects) can be evaluated only by relatively sophisticated regional exploration methods, while taking into account morphological data (X-ray, angiography).