A pneumothorax is an abnormal collection of air in the pleural space between the lung and the chest wall.Symptoms typically include sudden onset of sharp, one-sided chest pain and shortness of breath.In a minority of cases the amount of air in the chest increases when a one-way valve is formed by an area of damaged tissue, leading to a tension pneumothorax
This condition can cause a steadily worsening oxygen shortage and low blood pressure. Unless reversed by effective treatment, it can result in death. Very rarely both lungs may be affected by a pneumothorax. It is often called a collapsed lung, although that term may also refer to atelectasis.
A primary pneumothorax is one that occurs without an apparent cause and in the absence of significant lung disease, while a secondary pneumothorax occurs in the presence of existing lung disease. Smoking increases the risk as do lung diseases including COPD, asthma, and tuberculosis