Mediastinal shift

The abnormal displacement of mediastinal structures (trachea, heart, and great vessels) toward one hemithorax reflecting significant imbalance in intrathoracic pressure, volume, or structural forces.

Causes

• Increased pressure causing mediastinal displacement away from the affected side

  • Tension pneumothorax

  • Large pleural effusion

  • Hemothorax

  • Large empyema

  • Massive pulmonary cyst or bullae

  • Large thoracic tumor

• Reduced volume causing mediastinal displacement toward the affected side

  • Atelectasis: Anesthesia, blocked airways, external pressure, shallow breathing

  • Postoperative lobectomy

  • Pneumonectomy

  • Fibrotic lung volume loss