Questions concerning low intensity reduction in lung compliance

From the very early stages of reduction in lung compliance, the thoracic organs may be forcibly displaced, be subject to attraction or be prevented from fully carrying out their normal movement. By evaluating these changes on a chest radiogram we may assess, at least broadly, the existence of reduced compliance and to some extent its degree. Given that reduction of lung compliance can constitute the initial sign of establishment of a secondary neoplasm or other pathological condition in the lung, the potential of chest radiograms becomes wider both in the diagnostic sphere and in that of pathophysiological research. The more frequent displacement of the trachea to the right is, we believe, due to the greater overall mass of the right lung, so that in homogenous reduction of the lung compliance the total attraction to the right may be greater. The rising of the hemidiaphragms usually starts in their frontal region. This, we consider, is due to the different resistance to the reduction in lung compliance of the adjacent areas of the lung resulting from their different structure. The reduction of compliance in segments or subsegments adjacent to the hemidiaphragms produces local rising of them. When these segments are adjacent to the osseous thoracic wall they cause pleural thickening by activating the suction mechanism. The reduction in lung compliance may cause S-shaped distortion of the bronchovascular bundles of the lower lobes, displacement of the hili, blunting of the angle of the carina, curvature of the main bronchi and of the intrathoracic part of the trachea. All these changes can be seen on a chest radiogram.