Pneumothorax

Pneumothorax

Pneumothorax is defined as the presence of air or gas in the pleural cavity (ie, the potential space between the visceral and parietal pleura of the lung), which can impair oxygenation and/or ventilation.

It is useful to divide pneumothoraces into three categories :

• primary spontaneous: no underlying lung disease 
• secondary spontaneous: underlying lung disease is present 
• iatrogenic/traumatic 

Primary spontaneous

A primary spontaneous pneumothorax is one which occurs in a patient with no known underlying lung disease. Tall and thin people are more likely to develop a primary spontaneous pneumothorax.

Secondary spontaneous

When the underlying lung is abnormal, a pneumothorax is referred to as secondary spontaneous. There are many pulmonary diseases which predispose to pneumothorax including : 

1. Cystic lung disease

• bullae, blebs 
• emphysema, asthma 
• pneumocystis jiroveci pneumonia (PJP) 
• honeycombing: end stage interstitial lung disease 
• lymphangiomyomatosis (LAM) 
• Langerhans cell histiocytosis (LCH) 
• due to apical lung changes from ankylosing spondylitis 
• cystic fibrosis

2. parenchymal necrosis

• lung abscess, necrotic pneumonia, septic emboli, fungal disease,tuberculosis 
• cavitating neoplasm, metastatic osteogenic sarcoma 
• radiation necrosis 

3. other

• catamenial pneumothorax : recurrent spontaneous pneumothorax during menstruation, associated with endometriosis of pleura 
• rarely pleuroparenchymal fibroelastosis

Iatrogenic/traumatic

Iatrogenic/traumatic causes include :
Iatrogenic :

• percutaneous biopsy 
• barotrama, ventilator 
• radiofrequency (RF) ablation of lung mass 

Trauma :

• pulmonary laceration
• tracheobronchial rupture 
• acupuncture 

Clinical findings :

Findings on lung auscultation vary depending on the extent of the pneumothorax. Respiratory findings may include the following:

• Respiratory distress (considered a universal finding) or respiratory arrest 
• Tachypnea (or bradypnea as a preterminal event) 
• Asymmetric lung expansion: Mediastinal and tracheal shift to contralateral side (large tension pneumothorax) 
• Distant or absent breath sounds: Unilaterally decreased/absent lung sounds common, but decreased air entry may be absent even in advanced state of pneumothorax 
• Minimal lung sounds transmitted from unaffected hemithorax with auscultation at midaxillary line 
• Hyperresonance on percussion: Rare finding; may be absent even in an advanced state 
• Decreased tactile fremitus 
• Adventitious lung sounds: Ipsilateral crackles, wheezes 

Cardiovascular findings may include the following:

• Tachycardia: Most common finding; if heart rate is faster than 135 beats/min, tension pneumothorax likely 
• Pulsus paradoxus 
• Hypotension: Inconsistently present finding; although typically considered a key sign of tension pneumothorax, hypotension can be delayed until its appearance immediately precedes cardiovascular collapse 
• Jugular venous distention: Generally seen in tension pneumothorax; may be absent if hypotension is severe 
• Cardiac apical displacement: Rare findings. 

Treatment and prognosis

Treatment depends on a number of factors:

• size of the pneumothorax 
• symptoms 
• background lung disease/respiratory reserve