Spontaneous pneumothorax: rupture of blebs and bullae → air moves into pleural space with increasing positive pressure → ipsilateral lung is compressed and collapses
Traumatic pneumothorax
Closed pneumothorax: air enters through a hole in the lung (e.g., following blunt trauma)
Open pneumothorax: air enters through a lesion in the chest wall (e.g., following penetrating trauma)
Air enters the pleural space on inspiration and leaks to the exterior on expiration.
Air shifts between the lungs.
Tension pneumothorax
Disrupted visceral pleura, parietal pleura, or tracheobronchial tree
One-way valve mechanism, in which air enters the pleural space on inspiration but cannot exit
Progressive accumulation of air in the pleural space and increasing positive pressure within the chest
Collapse of ipsilateral lung; compression of contralateral lung, trachea, heart, and superior vena cava; angulation of inferior vena cava
Impaired respiratory function, reduced venous return to the heart