Mechanical ventilation is the most common cause of pneumothorax and pneumomediastinum. High positive end-expiratory pressures (PEEP) are used in ventilated patients in order to prevent atelectasis and improve oxygenation. However, high PEEP can result in the rupture of alveoli. When this occurs, air can dissect along the interstitium (pulmonary interstitial emphysema). This is primarily identified in the infant population. Air can dissect into the mediastinum (pneumomediastinum) or into the pleural space (pneumothorax).
A pneumothorax is identified by detecting the edge of the pleura outlined by air in the pleural space and air in the lung. It will look like a thin white line. Skin folds can mimic a pneumothorax. However, the appearance of a skin fold is that of an edge. If the lung is consolidated, you will not see the thin white line of the pleura, but instead will see the edge of the consolidated lung outlined by air in the pleural space.
Pneumothorax and pneumomediastinum can also occur in the setting of trauma, labor and delivery, and asthmatic exacerbations. Spontaneous pneumothorax can also occur in patients with underlying lung disease such as bulla for no apparent reason.
 C38
|
Pneumothorax |
 C39
|
Skinfold |
 C40
|
Right pleural effusion |
|
Status post thoracentesis |
 C42
|
Left lateral decubitus view shows right pneumothorax |
 C43
|
Comparison |
 C44
|
Deep sulcus sign on left - consistent with pneumothorax |
 C45,
 C46
|
CPAL, pneumomediastinum |
 C47,
 C48
|
Pneumoperitoneum (look under right hemidiaphragm on lateral) |
