Pneumothorax & Pleural Effusions - What are they?
Pneumothorax occurs when air becomes trapped between a lung and the chest wall, having entered this space either from the lungs or from outside the body.
Classifications of Pneumothorax are:
Primary spontaneous pneumothorax
Spontaneous pneumothorax develops for no apparent reason in an otherwise healthy person. This is the most common type of pneumothorax. It is thought to be due to a tiny tear of an outer part of the lung - usually near the top of the lung. It is often not clear why this occurs however, the tear often occurs at the site of a tiny 'bleb' or 'bullae' on the edge of a lung. The wall of the 'bleb' is not as strong as normal lung tissue and may tear. Air then escapes from the lung but gets trapped between the lung and chest wall.
Secondary spontaneous pneumothorax
This means that pneumothorax develops as a complication (a 'secondary' event) of an existing lung disease. This is more likely to occur if the lung disease weakens the edge of of the lung in some way. This may then make the edge of the lung more liable to tear and allow air to escape from the lung. For example, a pneumothorax may develop as a complication of COP (chronic obstructive airways disease) especially where lung bullae have developed in this disease. Other lung diseases that may be complicated by a pneumothorax include pneumonia, tuberculosis, sarcoidosis, cystic fibrosis, lung cancer and idiopathic pulmonary fibrosis.
Other causes of pneumothorax
An injury to the chest can cause a pneumothorax such as military trauma, injuries sustained in road traffic accidents or a penetrating injury to the chest. Surgical operations to the chest mat also cause a pneumothorax.
In cases where the air accumulates rapidly, a tension pneumothorax is present which need immediate attention. Untreated, pressure build-up will crush the blood vessels carrying blood back to the heart causing cardiac arrest that may be fatal within a few minutes.
The lungs are covered by a membrane or lining, called the pleura, which has an inner layer and an outer layer. The inner layer covers the lungs. The outer layer lines the rib cage and diaphragm, which is a sheet of muscle which separates the chest from the abdomen.
The pleura produces a fluid which acts as a lubricant that helps you breathe easily, allowing lungs to move in and out smoothly. Sometimes, too much of this fluid can build up between the two layers of the pleura; this is called a pleural effusion.