The term pneumothorax comes from a combination of words pneumos (air) and thorax (chest). It is a pathological condition, when there is air in the thoracic cavity.
First, it is necessary to know some information about the anatomy of the chest and lungs. Each of the two lungs is located in the so-called chest cavity (pleural cavity). Each chest cavity is lined with a thin membrane known as pleura. The lung fills almost the whole area of the cavity, there is only a small place left around the lung. This space contains vacuum with negative pressure, which allows dilation of the lung during inspiration. When the air gets into the pleural cavity, the vacuum disappears and the positive pressure forces the affected lung to collapse.
There are two main ways how the air can get into the pleural cavity – either through the chest wall or through the airways including the lungs. The leakage of air through the chest can occur in deep wounds (car accidents, stabbing, gunshot wounds).
The air from the airways usually enters the pleural cavity in case of a lung rupture. The rupture may be from an unknown cause in a previously completely healthy individual, this typically happens in young men and we refer it to as the spontaneous pneumothorax. The rupture is more typical in certain types of lung emphysema and in patients with artificial lung ventilation when the lung may be torn by the increased pressure in the airways.
Relatively often the pneumothorax occurs accidentally as a complication of insertion of the intravenous catheter into the subclavian vein. This situation can cause the pneumothorax by both above-mentioned mechanisms – the needle may perforate the chest into the pleural cavity or it can directly perforate the lung.
A pneumothorax can be divided into several types:
This pneumothorax occurs when the air gets into the chest cavity (either through the chest wall or the lung), but the opening quickly closed. Small closed pneumothorax may be asymptomatic or cause only short-term chest pain. The air may spontaneously absorb and the pneumothorax heals.
In this case, the communication between the pleural cavity and surroundings stays open. The pleural cavity is usually filled with a larger amount of air causing the collapse of lung on the affected side. The situation manifests with a sudden chest pain with dry cough and shortness of breath.
This is a deadly form of pneumothorax. It is a semi-opened pneumothorax when a piece of tissue near the pathological opening of the pleural cavity acts as a valve. While you inhale, it allows the entry of air into the pleural cavity, but when you exhale, the tissue closes the hole and prevents the air from exhaling. During each breath, the amount of pleural air increases, the pleural cavity gets inflated and its volume compresses other chest organs including the other lung. First symptoms resemble the open pneumothorax, but the shortness of breath worsens and without urgent treatment, it leads to suffocation.
Scheme -The collapse of the lung in pneumothorax, red arrows show the direction of compression
The clinical manifestations together with physical examination (decreased or missing breathing sounds of the side of affection) are very suspicious and we should perform an urgent chest X-ray, which clearly shows the air in the pleural area and compression of the lung. In tension pneumothorax, the chest organs (heart, trachea) are usually pushed towards the other side of the chest.
In all cases, bed rest and avoiding the physical activity is necessary. Oxygen should be administered when the symptoms of dyspnea are present. Further procedures depend on the type of the pneumothorax. Small closed pneumothorax may be only monitored without any treatment as the air may absorb itself. Larger amount of air may be carefully aspirated by a needle.
Extensive or open pneumothorax is usually treated by drainage. The doctor cuts a small hole in the chest wall and inserts a catheter into the affected pleural cavity connecting it to a suction device that suck the air out and form a negative pressure allowing the lung to expand. When the pneumothorax is caused by a chest wound, it should be closed and treated by a surgeon. If the pneumothorax is caused by a lung rupture, it is usually fully sufficient to wait as the continuous drainage causes the hole to close spontaneously.
The tension pneumothorax must be treated urgently in two steps. First, it is necessary to convert it into the open pneumothorax, i.e. to puncture the chest cavity by a hollow needle that allows the air to escape and prevent suffocation. The resulting open pneumothorax should be further solved by the above-mentioned conventional drainage.