Subcutaneous Emphysema in Trauma Patients

Primary Mechanisms of Air Entry

• Air enters the subcutaneous tissues directly through the stab wound penetrating the chest wall, creating a pathway between the pleural space and soft tissues 1, 2.
• During spontaneous breathing, air can enter through the chest wall defect during the inspiratory phase when intrathoracic pressure becomes negative 1, 2.

Iatrogenic Causes from Chest Tube Management

• Subcutaneous emphysema develops when air communicates with subcutaneous tissues through a malpositioned, kinked, blocked, or clamped chest tube 3, 4.
• If a chest tube is clamped while still bubbling, this prevents air egress from the pleural space, forcing air to track into surrounding tissues 5, 3, 6.

Secondary Mechanisms

Tension Pneumothorax Development

• Improper use of occlusive dressings over open chest wounds can trap air in the pleural space, increasing intrathoracic pressure and forcing air into subcutaneous tissues 1, 7, 2.
• When air cannot exit through the chest wound due to occlusive dressing, rising pleural pressure drives air along tissue planes 1, 2.

Associated Injuries

• Tracheobronchial injury from the stab wound can allow air to leak from the airway into mediastinal and subcutaneous tissues 4.

Clinical Significance and Monitoring

Extent and Progression

• Most cases are cosmetically concerning but clinically benign, subsiding within days 3.

Critical Warning Signs

• If a patient with a chest tube develops worsening subcutaneous emphysema, immediately check for tube clamping, kinking, or displacement 3, 4.
• Development of breathlessness or rapid progression of emphysema indicates potential tension pneumothorax or airway compromise 5, 3, 4.

Key Management Pitfalls to Avoid

• Never clamp a bubbling chest tube - this converts a manageable pneumothorax into potential tension pneumothorax and worsens subcutaneous emphysema 5, 3, 6.
• Do not apply fully occlusive dressings to open chest wounds without close monitoring, as this traps air and increases subcutaneous emphysema 1, 7, 2.
• Ensure chest tubes remain patent and properly positioned with confirmation by chest radiography 3, 4.