Pneumomediastinum not associated with lesion of mediastinal organs.

A review of 2,092 patients who had sustained closed thoracic trauma or undergone mechanical ventilation was made in order to clarify the incidence, clinical picture, pathogenesis and prognosis of pneumomediastinum without pneumothorax or lesion of mediastinal organs. Air in the mediastinal space was observed in ten patients (0.5% of cases). Bronchial and esophageal lesions were excluded at bronchoscopy and esophagoscopy. The clinical presentation included subcutaneous emphysema of the neck, without signs of mediastinitis. No patient had pain or dyspnoea. Trauma or barotrauma were assumed to have caused sudden rise in the intrapulmonary pressure, leading to passage of air from the parahilar alveoli into the mediastinum along the peribronchial and perivascular spaces. Management was conservative and the prognosis good, with normalization of the chest radiogram usually within a week.