Pneumothrax is a collection of air within the pleural space. Most commonly pneumothorax is caused by trauma. Other common causes are iatrogenic (biopsy or barotrauma), or spontaneous pneumothrax (most often in tall, thin, young men). Other causes include emphysema, asthma, lymphangioleiomyomatosis (approximately 75% develop pneumothorax), eosinophilic granuloma (approximately 20%), lung abscesses, tuberculosis, or cavitating neoplasm. Catamenial pneumothorax are recurrent and associated with endometriosis of the pleura.
Simple pneumothorax can be seen as a peripheral, usually non dependent lucency. A white line representing the pleural viscera will be visible. The ipsilateral lung will be compressed. If the patient is supine, the only sign of a pneumothorax may be a deep sulcus. Small pneumothorax may only be visible on lateral decubitus film (affected side up), or expiratory films. CT is the most sensitive imaging modality however.
Signs of a tension pneumothorax include midline shift, flattened diaphragm, and splaying of the ribs. As the pressure within the thorax increases, venous return to the heart is compromised. Tension pneumothroax is a life threatening condition, which requires urgent consultation with the ordering physician for placement of a needle thoracostomy.