Tension pneumothorax

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p. a.-X-ray image of a left-sided tension pneumothorax before (above) and after (below) placement of a chest drain. The shift of the mediastinum towards the healthy side can be clearly seen.
Classification according to ICD-10
J93.0 Spontaneous tension pneumothorax
S27.0 Traumatic pneumothorax
ICD-10 online (WHO version 2019)

The tension pneumothorax is a special and life-threatening form of the pneumothorax . It occurs when air enters the pleural space through an injury without being able to escape again. During inhalation (inspiration), air can enter the pleural space either from the outside (e.g. through a puncture) or from the inside (e.g. through a torn lung lobe ). During exhalation (exhalation), the injury is closed from the inside, like a check valve , so that the air can no longer escape and is instead distributed in the pleural space. This is why this injury is also known as valve pneumothorax . As the volume of air increases, the intrathoracic pressure on the injured side increases and displaces the middle layer to the opposite side. This compresses the healthy lungs and vena cava . The venous compression throttles the venous return flow to the heart, whereby the stroke volume decreases dangerously.

causes

If a connection between the outside air and the pleural space is created due to a thoracic trauma , the affected lung collapses. In contrast to a "normal" pneumothorax, the air you breathe does not escape from the affected area during expiration , but remains in the increasingly widening pleural space due to a valve mechanism . When inhaled, air passes between the lung tissue and the pleura ( pleura visceralis and pleura parietalis ). During expiration, more and more air is now pressed into the intrathoracic space, which increases the intrathoracic pressure. This leads to a displacement of the middle skin ( mediastinum ) and also of the heart. This displacement of the heart in turn leads to an impaired venous return (kinking of the inferior and superior vena cava ). The otherwise intact lung on the opposite side is also compressed, which leads to an insufficient supply of oxygen . A distinction is made between an open (connection through a hole in the chest wall) and closed (connection through a tear in the lung) tension pneumothorax.

Symptoms

The patient suffers from shortness of breath ( dyspnea ) and develops increasing cyanosis (purple to bluish discoloration of the skin). The displacement of the heart and the venous vessels will cause the neck veins to congest as a visible sign. Due to the reduced backflow of the blood, the systolic blood pressure also falls (arterial hypotension ) and a compensatory tachycardia occurs .

In the further course, compression of the inferior and superior vena cava ( inferior vena cava and superior vena cava ) leads to reduced venous return and thus to hypoxia , which is caused by the poor overall condition of the patient, i.e. H. further drop in blood pressure, increasing dyspnoea / cyanosis becomes noticeable.

In addition, the high intrathoracic pressure can cause skin areas to bulge.

therapy

Immediate pressure relief is a vital measure for the patient. This is usually by chest tube (usually as Bülau drainage ) and a so-called Heimlich valve performed. When installing the thoracic drainage, a scalpel cut is made at a specific point in the intercostal space on the injured side and the thoracic drainage is then inserted into the pleural space . With the help of this tube, the air in the chest can now escape. The Heimlich valve works like a check valve . The defect may then be treated surgically.

Another simple method, which is rarely used due to its lower efficiency, is drainage using a simple cannula with a crucible valve , which is formed with the help of an incised rubber finger cot. Here, too, the valve closes on inspiration and opens during expiration, so that the pressure in the pleural cavity drops.

As an emergency measure (a tension pneumothorax can lead to death within a few minutes in unfavorable circumstances, it is not always better to have a more suitable instrument at hand), the sole opening of the pleural cavity is also suitable, for example by piercing several large-lumen cannulas or by opening the chest wall with a simple one Knife and then keeping this wound open, thus creating a pressure balance between the pleural cavity and the ambient air pressure. The tension pneumothorax is first converted into a simple pneumothorax , which is usually not acutely life-threatening.

literature