A sharp pain in the right or left side, shortness of breath, increased heart rate, dizziness and an increased respiratory rate are some symptoms of a collapsed lung, or pneumothorax. The pain will get progressively worse, because a collapsed lung generally will not resolve on its own. Pressure in the pleural space, the area between the lungs and the chest wall, is normally lower than the pressure inside the lungs or outside the chest. When air enters the pleural space either through the chest wall from trauma, or between the lung and the pleural space, the lung will either partially or completely collapse.
Blebs
One type of collapsed lung, called a "primary spontaneous pneumothorax," can occur when a small air pocket on the lung ruptures, creating a conduit between the lung and the pleural space. These air pockets, called blebs, develop when a portion of the lung tissue is already weak. A sudden change in air pressure causes the bleb to overextend and rupture, which is similar to blowing up a balloon until it bursts. This type of pneumothorax is generally mild.
Pre-Existing Lung Disorders
Another kind of collapsed lung, a "secondary spontaneous pneumothorax," can occur in individuals with a pre-existing lung disorder, such as COPD, particularly emphysema. Tuberculosis, pneumonia, cystic fibrosis and lung cancer are all contributing factors for secondary spontaneous pneumothorax, because the lung tissue is already damaged and weak. This type of pneumothorax tends to be more severe, because the lung is already compromised by a reduced lung capacity, and a pneumothorax simply makes a bad situation worse.
Trauma
A collapsed lung caused by an injury of some kind is called a "traumatic pneumothorax." This type can be life-threatening if not treated immediately. Some types of trauma that can cause a pneumothorax include blunt force to the chest; an object, such as a knife or bullet, penetrating the chest wall; a car accident; or a severe fall. A traumatic pneumothorax can also be the result of any medical or surgical procedure that mistakenly punctures the lung, such as cardiopulmonary resuscitation, bronchoscopy or biopsy.
Change in Pressure
A "tension pneumothorax" occurs from the sudden change in pleural pressure. As the air pressure increases inside the pleural space, the lung can no longer expand, which can cause a full or partial collapse of the lung. A tension pneumothorax happens quickly and can be fatal if circulation and respiration are not restored immediately.
Pulmonary Fibrosis
Pulmonary fibrosis occurs because of scarring that occurs inside and outside the air sacs within the lung. As the scars form, the lung tissue becomes stiff, making it more difficult for oxygen to be exchanged. This scarring cannot be reversed. According to the American Lung Association, cigarette smoking, viral infections, pollutants, certain medications, genetics and gastroesophageal reflux disease may increase the risk of pulmonary fibrosis and a collapsed lung.
