fev Introduction Definition restricted lung expansion results in reduced lung volumes (TLC and FVC) Pathophysiology poor breathing mechanics with normal lung function muscle weakness login to view 1 more bullet chest wall limitation login to view 1 more bullet ↓ pleural compliance login to view 1 more bullet interstitial lung diseases (diffuse parenchymal lung disease - DLCO) results in reduced lung compliance and increased elastic recoil the primary mechanism of resting hypoxemia in patients with interstitial lung disease is a diffusion limitation, with DLCO defect contributing to hypoxemia with activity increased expiratory flow rates due to increased radial traction (result of increased elastic recoil) on airway walls login to view 1 more bullet types login to view 18 more bullets Studies Pulmonary function tests FEV1 sec/FVC ratio should be normal approximately normal because both FEV1 sec and FVC are reduced ↓ FVC and TLC key finding for restrictive lung diseases (TLC must be reduced)