Signs of Loss of Lung Volume

Generalized

• Shift of Mediastinum: The trachea and heart gets shifted towards the atelectatic lung.
• Elevation of Diaphragm: The diaphragm moves up and the normal relationship between left and right side gets altered.
• Drooping of Shoulder
• Crowding of Ribs: The interspace between ribs is narrower compared to the opposite side.

Movement of Fissures

You need a lateral view to appreciate the movement of oblique fissures. Note forward movement of oblique fissure(A) in LUL atelectasis. (In some cases you can see oblique fissur in PA view. Review the RLL atelectasis film)

Movement of transverse fissure can be recognized in the PA film.

Movement of Hilum

The right hilum is slightly lower than left normally. This relationship will change with lobar atelectasis. Note right hilum is pulled up folowing RUL resction and is now at the same level as left hilum.

Compensatory Hyperinflation

Compensatory hyperinflation  as evidenced by increased radiolucency and splaying of vessels can be seen with the normal lobe or opposite lung. (CXR of a patient with RUL resection. Note hyperluscent RLL and RML)

Alterations in proportion of Left and Right Lung

The right lung is approximately 55% and left lung 45%. In atelectasis this apportionment will change and can be a clue to recognition of atelectasis. In a given case one or more of these features will alert you to the presence of atelectasis. Note in this patient with RLL atelectasis overall right lung is smaller than left lung.

Hemithorax asymmetry

In normals right and left henithorax are equal in size. The size of hemithorax will be asymmetrical and smaller on the side of atelectasis.