Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Semi-upright portable view of the chest demonstrates small right apical pneumothorax , which has decreased in size since study obtained four hours prior . No appreciable left pneumothorax . Subcutaneous gas of the chest wall is unchanged . Low lung volumes . No focal consolidation or pleural effusion . Hilar and mediastinal silhouettes are unchanged . Heart size is normal . Trace amount of free air is seen under the right hemidiaphragm .
    OUTPUT:
    
In comparison to study obtained four hours prior , there is interval decrease in right apical pneumothorax , now small .