Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Asymmetric lucency of the lung apices as compared to the bases is consistent with patient 's known history of emphysema . Lung volumes are low , likely related to recent postoperative state . There are increased linear basal opacities , most likely atelectasis . A trace left pleural effusion is also likely . No pulmonary edema is identified . Mediastinal and hilar contours are within normal limits . Cardiac margins are obscured by bibasilar opacities . There is a small - to - moderate amount of subdiaphragmatic free air consistent with patient 's recent abdominal surgery .
    OUTPUT:
    
Low lung volumes with bibasilar opacities , most likely atelectasis . No pulmonary edema or large effusions .