Residual volume is decreased in patients with Interstitial Lung Disease Progressive dyspnea and presence of bibasilar end-inspiratory crepitations suggests a diagnosis of interstitial lung disease Dyspnea is a common and prominent complaint in patients with Interwtitial Lung Disease(ILD)'-Harrison 17th/1645 `Most commonly, physical examination reveals tachypnea and bibasilar end - inspiratory dry crackles which are common in most forms of ILD' - Harrison 17th/1645 Interstitial Lung Disease (ILD) may be associated with connective tissue diseases 'ILDs have been difficult to classify because > 200 known individual disease are characterized by diffuse parenchymal lung involvement either as primary condition or as a significant pa of a multiorgan process, as may occur in connective tissue disorders (CTD's)'- Harrison 17th/1643 Interstial Lung disease produce a restrictive effect on Pulmonary Function Testing `Most forms of ILD produce a restrictive defect with reduced total lunz capacity (.TLC), functional residual capacity and residual volume (.IRV). Forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) are reduced; but, the FEV1/FVC ratio is normal or increased' - Harrison 17th /1646 HRCT is a useful test for ILD HRCT is the investigation of choice for Interstitial Lung Disease.