Department of Diving and Hyperbaric Medicine, Naval Medical Institute, Kiel, Germany.
A 22-yr-old healthy male diver performed a dive using a closed circuit oxygen rebreathing apparatus according to normal procedure. After the dive he developed clinical symptoms of mediastinal emphysema. A chest X-ray taken 1 d after the dive showed a discrete "tram track" sign in the left paracardial region. Spiral volumetric computed tomography of the chest 4 d postinjury detected a small subpleural emphysematous bulla next to the left ventricle, the pneumomediastinum being absorbed in the meantime. Clinical outcome of pulmonary decompression barotrauma in the case of oxygen rebreathing may be different from that in compressed air diving, due to the altered gas physics. The necessity for computed tomography of the chest is emphasized, preferably using the spiral mode, in any case of suspected pulmonary barotrauma.