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What Is The Pathophysiology Of Tension Pneumothorax?

Pneumothorax is the condition in which the pleural cavity is filled with the air. The air of the pleural cavity imparts pressure on the lungs leading to lung collapse. Pneumothorax can be divided into various types such as spontaneous, traumatic or iatrogenic; open, closed or valvular; local or generalized and; chronic or acute. Tension pneumothorax is a type of valvular pneumothorax in which the pressure in the pleura cavity is progressively build up, usually due to lung injury, which allows the air to enter in to pleural space, but does not allow the air to move out resulting in the abnormalities in the heart and compression of vena cava. The condition if left untreated may result in fatal consequences.

The pathophysiology of tension pneumothorax is complicated. Tension pneumothorax is the type of pneumothorax which is characterized by the presence of air in the pleural cavity. Pleural cavity surrounds the lung and helps the functioning of lungs during respiration.

In the normal conditions, the pleural space has the negative pressure as compared to the atmospheric pressure. This pressure is created due to a situation in which the lungs get contracted and the chest wall gets expanded. In such a condition, alveolar pressure is more than the pleural pressure.

However, in the tension pneumothorax condition a system similar to one-way valve system is evolved. This system is evolved due to the injury in the lungs. In such a system, the air is concentrated in the pleural cavity during respiration, but does not allowed to move out from the pleural cavity. This results in the increasing pressure in the pleural cavity. This leads to insufficient expansion of lungs on the side of pneumothorax. The lung collapse pushes the heart from its position towards the contralateral side, resulting in the compression of arteries of the heart mainly vena cava. Thus, the cardiac output is decreased. The presence of bullae also determines the existence of tension pneumothorax. The patient with larger bullae is more likely to experience tension pneumothorax a compared to the patients with smaller size bullae.

As the tension pneumothorax involves the cardiac system, thus the symptoms experienced by the patients will be related to both respiratory and cardiovascular system. The signs of tension pneumothorax include the following:

Shock with hypotension and pallor resulting from hypoxia and reduced venous return.
The patient may experience dyspnea and anxiety.
Neck veins seem to be distended.
Absent breathing sounds.
Decreased lung capacity.
Respiratory distress
Progressive tachycardia
If immediate medical intervention not done then the patient may experience fatal cardiopulmonary collapse.

Treatment Of Tension Pneumothorax

The primary therapy used in the management of tension pneumothorax is the decompression of the chest to relieve the excess pressure. It is recommended that the decompression is done by using the point of entry as the fourth or fifth intercostal space at the anterior axillary line. This will avoid the pectoris muscle and contains less adipose tissue. However due to certain drawback such as inadequate needle length, chest wall penetration problem or poor retention make this a non-definitive treatment for tension pneumothorax. Adequate air drainage should be maintained until the underlying wound heals and there is no air leak.

Conclusion

Tension pneumothorax, if left untreated, is a life threatening condition occurred due to the progressive build up of pressure in the pleural cavity. The pressure inside the pleural cavity is increased due to one way system leading to the compression of vena cava. This compression of vena cava leads to cardiac symptoms such as hypotension and shock reduced diastolic return and cardiac output. The patient experiences shortness of breath and fatigue. The treatment of tension pneumothorax is the decompression of the chest to relieve pressure. The decompression should be done by a thoracic surgeon and the drainage should be maintained till the injury is resolved and the air leak is stopped.

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What Is The Pathophysiology Of Tension Pneumothorax?