Pneumomediastinum.

Pneumomediastinum is a rare pathological condition with air in the mediastinum outside the trachea and oesophagus. The etiology may be spontaneous/resulting from exertion, traumatic, iatrogenic or it may be due to inflammation, neoplasm or perforation of a hollow abdominal organ. In pneumomediastinum resulting from exertion, a pressure gradient occurs and this causes rupture of marginally situated pulmonary alveoli. Air escapes from the alveoli into the perivascular adventitia and dissects its way along the vessels to the mediastinum. The commonest symptoms are pain in the thorax in 80-90% of the patients, followed by sensation of oppression and dysphagia. Stethoscopic examination reveals crepitation synchronous with pulse and respiration in half of the cases. The diagnosis is verified by radiographic examination of the thorax where air can be seen as vertical radio-translucent regions in the mediastinum and along the borders of the heart. Patients with pneumomediastinum should be admitted to hospital for investigation as treatment of a possible basic condition, e.g. rupture of the oesophagus or bronchus, is important. In uncomplicated cases, the mediastinal emphysema disappears in the course of a week. Mediastinotomy with incisions for relief of pressure may prove necessary.