Definition for tension pneumothorax

A tension pneumothorax is a life-threatening condition that results from a progressive deterioration and worsening of a simple pneumothorax, associated with the formation of a one-way valve at the point of rupture.

Upon inspiration, when the pressure inside the chest and pleural cavity lessens as a result of the respiratory muscles increasing chest dimensions, air is sucked in through this one way valve, into the pleural space. Because expiration is a passive process, there is an insignificant amount of pressure created to force the air back out of the pleural cavity. This condition over time results in a gradual accumulation of air to the degree that it begins to put pressure on the mediastinum, compressing the heart and decreasing cardiac output due to the reduced amount of diastolic filling of the ventricles, and also putting pressure against the trachea, deviating it from the midline. Because of the increased thoracic pressure, venous return to the heart is decreased, causing a backup of blood into the venous system, as is evidence by distended jugular veins. less