The evaluation of pneumomediastinum in blunt trauma patients

Pneumomediastinum occurs in up to 10% of patients with blunt thoracic and cervical trauma. Mandatory evaluation of all patients with bronchoscopy and esophageal imaging to exclude a major injury has been recommended. There is little data on the safety or efficacy of this approach. We evaluated the incidence of major injuries associated with pneumomediastinum, the accuracy of diagnostic modalities, and the results of observation versus aggressive evaluation.

Medical records of all blunt trauma patients diagnosed with pneumomediastinum and/or aerodigestive tract injury between 1998 and 2005 were reviewed. The patient's hospital course was reviewed for demographic data, admission diagnoses, diagnostic imaging and procedures, operations, missed injuries, length of stay, and mortality.

The review identified a total of 136 patients with pneumomediastinum, and an additional 22 patients with thoracic aerodigestive tract injuries but without pneumomediastinum. Only patients with pneumomediastinum were considered in subsequent analysis. Pneumomediastinum was detected by CT scan in all 136 (100%) patients, although identified on plain radiograph in only 20 (15%) patients. Computed tomography findings were suspicious for a major aerodigestive tract injury in 27 (20%) patients. Ten (37%) of these 27 patients had an injury requiring operative intervention: five (4%) laryngeal injuries, three (2%) tracheal disruptions, and two (1%) esophageal perforations. Eighty-one patients (60%) never had endoscopic evaluation. There were no delayed diagnoses, missed injuries, or complications in the observation-only cohort. The overall sensitivity and specificity of CT scan for major aerodigestive tract injury was 100% and 85%, respectively.

Major airway or esophageal injury is an uncommon cause of pneumomediastinum. CT scan was able to identify patients at high risk for aerodigestive injury in all cases, and should be the preferred screening tool for airway injury in patients with pneumomediastinum.