Secondary pneumomediastinum: a retrospective comparative analysis.

Pneumomediastinum is an uncommon radiographic finding of potential clinical significance. Secondary pneumomediastinum (SPM) has a variety of etiologies that can lead to potentially morbid outcomes. There are limited data regarding the etiologies, diagnosis, and outcomes of this entity. A retrospective comparative study was conducted over an 11-year period of patients developing pneumomediastinum secondary to a specific pathologic or traumatic event. Forty-five patients were identified with an underlying condition resulting in SPM. Demographic data, radiologic findings, length of hospital stay, and mortality were recorded. Statistical comparison was conducted between patients with blunt thoracic trauma- and barotrauma-induced pneumomediastinum. Logistic and multiple linear regression analyses were performed to discover factors predictive of mortality and length of hospital stay. Median age of the patients was 40 years and 69% were men. Subcutaneous emphysema was identified in 44%, pneumothorax in 47%, and pleural effusion in 11%. Pneumomediastinum was identified by plain radiograph (CXR) in only 47% compared to 100% by computed tomogram (CT scan). Average length of hospital stay was 19 days and mortality was 38%. Patients with blunt thoracic trauma had a lower sensitivity for CXR to discover pneumomediastinum, were more likely to develop subcutaneous emphysema or pneumothorax, and had lower mortality and length of hospital stay compared with those with barotrauma-induced pneumomediastinum. Barotrauma was an independent predictor for hospital mortality. Secondary pneumomediastinum is a morbid condition with distinctive etiologies, radiologic findings, and outcomes. Barotrauma-induced pneumomediastinum is associated with a prolonged recovery and high mortality rate.