Subcutaneous Emphysema

This patient had severe COPD and presented with spontaneous pneumothorax and respiratory distress. CXR and CT showed severe pulmonary emphysema, bilateral pneumothoraces, pneumomediastinum and extensive subcutaneous emphysema.

Subcutaneous emphysema, strictly speaking, refers to air in the subcutaneous tissues. But the term is generally used to describe any soft tissue emphysema of the body wall or limbs, since the air often dissects into the deeper soft tissue and musculature along fascial planes.

Causes of subcutaneous emphysema can be divided into:
- Air arising internally (eg. pneumothorax, pneumomediastinum, pulmonary interstitial emphysema, perforated hollow viscus in the neck, fistula tract)
- Air introduced externally (eg. penetrating trauma, surgery, percutaneous intervention)
- Air produced de novo (gas-producing infections)

Clinically subcutaneous emphysema is felt as crepitus and, if extensive, it may cause soft tissue swelling and discomfort. The condition is typically benign and treatment is directed at the underlying cause, while the subcutaneous air is absorbed over time. However in rare instances treatment may involve release of the air by surgical division of the soft tissues or placement of catheters.

References:
1. Medscape.com
2. Beck PL, et al. Simple Construction of a Subcutaneous Catheter for Treatment of Severe Subcutaneous Emphysema. Chest 2002;121:647-649

Credit: Dr Donna D'Souza