What is the frequency of mediastinum (mediastinal) pneumothorax?

Frequency of Mediastinal Pneumothorax (Pneumomediastinum)

Mediastinal pneumothorax (pneumomediastinum) is rare, occurring in approximately 5.9% of patients with blunt thoracic trauma and even less frequently as a spontaneous event, with most cases following a benign clinical course requiring only conservative management. 1

Incidence in Different Clinical Contexts

Trauma-Related Pneumomediastinum

• In blunt thoracic trauma patients, pneumomediastinum occurs in 5.9% of cases, with combined pneumomediastinum and pneumopericardium in 1.5%, and isolated pneumopericardium in 0.2% 1
• The presence of pneumomediastinum following blunt trauma is typically incidental and benign, with no mortality directly attributable to missed mediastinal aerodigestive injury 1
• Increasing age and presence of flail chest are significantly associated with higher rates of pneumomediastinum (p < 0.001 and p = 0.005, respectively) 1

Spontaneous Pneumomediastinum

• Spontaneous pneumomediastinum is a rare disease affecting predominantly young males (average age 24 years, male-to-female ratio approximately 2.6:1) 2
• A systematic review of 22 years of data identified only 600 patients across 27 published series, highlighting its rarity 3
• Morbidity occurs in only 2.8% of cases, with no mortality reported in spontaneous cases 3

Risk Factors and Precipitating Events

Common Triggers

• Athletic activity, drug abuse (particularly hookah consumption), and history of asthma play apparent roles in disease development 3, 2
• Specific precipitating events include: coughing spells (most common), asthma exacerbations, iterative vomiting, childbirth, and COPD exacerbations 2
• Smoking significantly increases pneumothorax risk, which can lead to secondary pneumomediastinum 4

Iatrogenic Causes

• Invasive procedures are the leading cause of iatrogenic pneumomediastinum 4
• Most common iatrogenic causes: transthoracic needle aspiration, subclavian vessel puncture, thoracentesis, and pleural biopsy 4
• Approximately 10% of patients undergoing transthoracic needle aspiration of the mediastinum require catheter placement for pneumothorax evacuation 5

Clinical Complications

Tension Pneumomediastinum

• The most common complication of pneumomediastinum is tension pneumothorax 3
• Tension pneumomediastinum is a rare but potentially fatal entity that can lead to cardiac arrest, with mortality rates of 40% reported in COVID-19 ARDS patients who developed this complication 6
• In COVID-19 patients with ARDS requiring invasive ventilation, secondary lung infection can precipitate tension pneumomediastinum 6

Important Clinical Caveats

Diagnostic Considerations

• Pneumomediastinum is distinct from pneumothorax and requires different management approaches 3, 7
• Diagnosis is confirmed via chest X-ray or CT scanning, with CT recommended when plain radiographs are obscured by surgical emphysema 5, 7
• Clinical history is not a reliable indicator of pneumothorax or pneumomediastinum size 5, 4

Management Principles

• Conservative management is appropriate for uncomplicated cases, as mediastinal tissues slowly resorb the air 3, 7
• Invasive procedures are only indicated when complications (such as tension pneumothorax) develop 3
• Outcome is favorable in virtually all spontaneous cases, with no recurrence after minimum 3-year follow-up 2