(See also Overview of Thoracic Trauma.)
Spontaneous pneumothorax is discussed elsewhere.
Some patients with traumatic pneumothorax have an unsealed opening in the chest wall. When patients with an open pneumothorax inhale, the negative intrathoracic pressure generated by inspiration causes air to flow into the lungs through the trachea and simultaneously into the intrapleural space through the chest wall defect. There is little airflow through small chest wall defects and hence few adverse effects. However, when the opening in the chest wall is sufficiently large (when the defect is about two thirds the diameter of the trachea or larger), more air passes through the chest wall defect than through the trachea into the lung. Larger defects can eliminate ventilation on the affected side. Inability to ventilate the lungs causes respiratory distress and respiratory failure.
In awake patients, the chest wound is painful and patients have respiratory distress and other manifestations of pneumothorax. The air entering the wound typically makes a characteristic sucking sound.
Immediate management of open pneumothorax is to cover the wound with a rectangular sterile occlusive dressing that is closed securely with tape on only 3 sides. Thus, the dressing prevents atmospheric air from entering the chest wall during inspiration but allows any intrapleural air out during expiration. Tube thoracostomy should be done when the patient is stabilized. The wound may require later surgical repair.