It occurs when air collects in the space between the lung and the chest wall. The amount of air outside the lung determines the extent of collapse. It may be fatal if the collapse becomes large, or the pressure outside the lung is greater than inside. Pneumothorax may result from a puncture due to surgery, biopsy or other medical procedures. It can also occur after an injury, such as a gunshot or knife wound.
Sudden cases can occur in otherwise healthy adults without any piercing wound.
The lung may rupture during exercise or coughing. This may happen to people with an underlying lung disease or birth defect. Collapsed lung is a common problem in premature infants. The signs of collapsed lung are sudden, sharp chest pain, lopsided chest wall movement, shortness of breath, and bluish lips and fingernails. If it becomes more severe, the person may have weak and rapid pulse, pale skin, bulging neck veins, and a very hard time breathing.