Pneumothorax is air in the pleural space.
- Air (black) in pleural space. No lung markings in pleural space.
- Recognition of atelectatic lung (lung
margin). The lung recoils to a resting state as the negative pressure in
the pleura is lost (relaxation
- Shift of mediastinum to the opposite side. The
mediastinum is held in the middle by balance between pleural pressures. When the negative pressure on the side of
the pneumothorax is lost, the mediastinum gets pulled by the normal negative pressure from the
opposite side. Progressive shift subsequently could result from a push secondary to
- Larger hemithorax. When negative pressure in
the pleura is lost, the chest wall
reaches the TLC position. Note the following
chest tube the hemithorax returns to FRC position.
lung gets the entire cardiac output and the vascular markings become
Tension: Make a decision about tension by evaluating
the clinical situation, BP and pulse.
Radiologic signs are not reliable. The size of
pneumothorax or shift of mediastinum do not suggest tension. Mediastinum will be
shifted to the opposite side even without tension, as the negative pressure is
relatively more compared to the side with pneumothorax. A very small
pneumothorax in a patient with pre-existing lung disease can cause more