It is usually classified on the basis of its causes. Pneumothoraces are classified as traumatic and nontraumatic (spontaneous).[7] Nontraumatic pneumothoraces are further subdivided into primary (occurring in persons with no known history of lung disease) and secondary (occurring in persons with a known history of lung disease, such as chronic obstructive pulmonary disease).[8]
Pneumothoraces may also be further described as simple pneumothorax (no shift of the heart or mediastinal structures) or tension pneumothorax. It can also be classified as open (“sucking” chest wound) and closed (intact thoracic cage)