Shifts in the mediastinum (upper & lower) are of significant clinical & radiological importance reg. their pathology.

Tracheal position is the index of upper mediastinal position. Tracheal shift is an indication of upper mediastinum shift. Indicator for lower mediastinal shift is the position of the heart.

General Rule of thumb: if one side of the chest cavity has an increase in pressure (such as in the case of a pneumothorax) the trachea will shift towards the opposing side.

The mediastinum will shift towards the side with relatively higher negative pressure compared to the opposite side. Tracheal deviation can occur under the following conditions:

Deviated towards (Ipsilateral) diseased side

• Atelectasis – (Not related to pneumothorax)
• Agenesis of lung
• Pneumonectomy
• Pleural fibrosis

Deviated away from (Contralateral) diseased side

• Pneumothorax (pressure is higher & more positive in the diseased side i.e. negative pressure is higher on the opposite side) – See an example of a L pneumothorax here with mediastinal & tracheal shift away from diseased side.
• Pleural effusion
• Large mass

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