Tension pneumothorax
The tension pneumothorax is a special and life-threatening form of pneumothorax. It is formed by a valve mechanism in which during inhalation ( inspiration) air either from outside ( eg injection ) or from the inside (eg of torn lung lobe ) penetrates into the chest cavity. During exhalation ( expiration) the valve, such as a small piece of the chest wall, a door from the inside is pushed back, so that the air no longer escape and can only distribute in the chest cavity. Therefore, this violation is also called ventile. With increase of the air volume of the intrathoracic pressure increases on the injured side, displacing the mediastinum to the opposite side. In this way, the normal lung and the vena cava are compressed. The veins compression restricts venous return to the heart, causing the stroke volume decreases threatening.
Causes
Caused by a thoracic trauma, a connection between the outside air and the pleural space, the affected lung collapses. In contrast to a "normal" pneumothorax, however, the breath in expiration does not escape again from the affected area, but remains due to a valve mechanism in the now increasingly widening the pleural space. During inhalation, air passes between the lung tissue and pleura ( visceral pleura and parietal pleura ). During expiration will be pressed gradually more air into the intra-thoracic space, resulting in an increase in intrathoracic pressure results in. This leads to a displacement of the mediastinum ( mediastinal ) and also of the heart. This displacement of the heart in turn leads to a handicapped venous reflux ( kinking of the vena cava inferior and superior). Even the otherwise intact lung of the opposite side is compressed, which results in an insufficient supply of oxygen by itself. We distinguish between an open (compound through a hole in the chest wall ) and closed ( connection through crack in the lungs) tension pneumothorax.
Symptoms
The patient suffers from shortness of breath (dyspnea ) and developed an increasing cyanosis ( bluish discoloration of the skin to violet ). Due to the displacement of the heart and venous vessels will be a visible sign of the neck veins accumulate. Due to the reduced flow of blood falls beyond the systolic blood pressure ( arterial hypotension) and it comes to a compensatory tachycardia.
In the further course by compression of the lower and upper vena cava ( inferior vena cava and superior vena cava ) to reduced venous return and thus to hypoxia, which, by the poor overall condition of the patient that is further drop in blood pressure, increasing dyspnea / cyanosis becomes apparent.
In addition, areas of skin may protrude through the high intrathoracic pressure.
Therapy
Immediate relief is a vital measure for the patient. This is (usually as Bülau drainage) performed with a so-called Heimlich valve usually by chest tube. At installation of a chest tube cut with a scalpel at a certain location is carried out in the intercostal space on the injured side, and then inserted the chest tube into the pleural space. Use this hose can now escape located in the thorax air. The Heimlich valve works like a check valve. Subsequently, the defect will eventually managed surgically.
Another simple method, which is due to a lower efficiency of only rarely used is the drainage by means of a single cannula having a valve pot, which is formed by means of a notched rubber fingerstall. Again, the valve closes during inspiration and open during expiration, so that the pressure in the pleural cavity decreases.
As an emergency measure ( a tension pneumothorax can lead to death in certain circumstances, within minutes, not always suitable instruments Surgical is better right at your fingertips ) suitable is the sole opening the pleural cavity, for example, by inserting several large-bore cannulas or by opening the chest wall with a simple diameter followed by keeping open the wound, and thus the creation of a pressure balance between the pleural cavity and the ambient air pressure. Thus, the tension pneumothorax is first converted into a simple pneumothorax, which is not acutely life threatening in most cases.