2-48
2-48. PNEUMOTHORAX AND HEMOTHORAX
a. Pneumothorax is defined as the presence of air in the pleural space.
(1) This condition may occur after thoracentesis or pleural biopsy.
(2) It may also occur secondary to mechanical ventilation when use of excessive pressures results in tissue rupture. When there is a rupture of lung tissue (alveoli or visceral pleura), a "spontaneous" pneumothorax is said to have occurred.
(3) Chest trauma, such as a puncture or missile wound, allows air to enter the pleural space, also causing pneumothorax.
b. When air enters the pleural space through a hole in the lungs, the tissue around the edges of the hole acts as a valve, allowing air to enter the pleural space, but not to escape. This condition is called a tension pneumothorax because there is a build up of pressure (tension) within the pleural space. This pressure, if unrelieved, will cause lung compression and eventual collapse. Additionally, the mediastinum may be displaced, causing disrupted circulation.
(1) Tension pneumothorax may occur when there is a wound in the lung that does communicate with the exterior of the body. For example, a fractured rib may be pushed inward, tearing the lung and the surrounding pleura. Air can now escape from the lung, but is trapped in the pleural space.
(2) Tension pneumothorax may also occur when a sucking chest wound has been sealed with an occlusive dressing. The air will escape from the lung into the pleural space with each inspiration, but will be trapped due to the occlusive dressing over the exterior wound.
(3) Tension pneumothorax may also occur as a postoperative complication. The opening at fault may be leakage around the drainage tube, an undiscovered opening in the visceral pleura, or faulty suturing of resected lung tissue.
c. Hemothorax is the accumulation of blood in the pleural cavity. This condition usually accompanies chest trauma. Blood from lacerated lung tissue and torn blood vessels enters the pleural cavity and pools in the dependent area.
d. When air and blood are found in the chest cavity together, the condition is called hemopneumothorax.
e. Treatment for all the above conditions involves the removal of the air or blood from the pleural cavity, thereby allowing the lung to expand once again. This is routinely done by thoracentesis for small amounts of air or blood or by the insertion of chest tubes to drainage when a large amount of air or blood is involved. Other treatment measures involve administration of oxygen and analgesics.
