Any condition that leads to pneumothorax can cause a tension pneumothorax. In an uncomplicated pneumothorax, air can enter and leave the pleural space easily. In tension pneumothorax, however, air enters the pleural space with each breath and becomes trapped there. As the amount of trapped air accumulates, pressure builds up in the chest. The lung collapses on that side and may push the important structures in the center of the chest (such as the heart, major blood vessels, and airways) toward the other side of the chest. The shift may cause compression of the opposite lung and may affect the flow of blood returning to the heart. This situation can lead to low blood pressure, shock, and death.
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