In pneumothorax, air or gas accumulates between the parietal and visceral pleurae, causing the lungs to collapse. The amount of air or gas trapped determines the degree of lung collapse. In some cases, venous return to the heart is impeded, causing a lifethreatening condition called tension pneumothorax.
It is classified as either traumatic or spontaneous. Traumatic may be further classified as open (sucking chest wound) or closed (blunt or penetrating trauma). An open (penetrating) wound may in turn cause closed pneumothorax if communication between the atmosphere and the pleural space seals itself off. Spontaneous— also considered closed — can be further classified as primary (idiopathic) or secondary (related to a specific disease).
What are the causes :
It can result from:
- Ruptured congenital blebs
- Ruptured emphysematous bullae
- Tubercular or malignant lesions that erode into the pleural space
- Interstitial lung disease such as eosinophilic granuloma. Traumatic pneumothorax can result from:
- Insertion of a central venous access device
- Thoracic surgery
- Thoracentesis or closed access device
- Penetrating chest injury
- Transbronchial biopsy.
Spontaneous pneumothorax is a type of closed pneumothorax. The usual cause is rupture of a subpleural bleb (a small cystic space) at the surface of the lung. This rupture causes air leakage into the pleural spaces; then the lung collapses, causing decreased total lung capacity, vital capacity, and lung compliance — leading, in turn, to hypoxia.