• diving
• certification
• computed tomography
• chest

Toklu et al¹ have raised the question of whether routine high resolution computed tomographic (CT) scanning of the chest should form part of the initial diving medical examination for occupational divers. The authors make this proposition in discussing their series of three divers in which pulmonary abnormalities were discovered on high resolution CT scan after occupational diving incidents. One case involved a bulla, the second multiple air cysts, and the last a subpleural bleb. The authors assume that the initial mechanism of injury in each case was pulmonary barotrauma associated with the lesions revealed.

One could argue whether the second and third cases may have involved arterialisation of venous bubbles rather than pulmonary barotrauma, but any uncertainty does not invalidate consideration of the authors’ contentions. It is widely agreed that lung cysts, bullae, and blebs may all predispose to pulmonary barotrauma, and most authorities recommend disqualification from diving if such lesions are found.^2–4 This report adds to others in which CT scans have revealed pulmonary abnormalities in diving accident victims where chest radiographs did not.^5,6 I have also managed a similar case of apparently undeserved arterial gas embolism after years of uneventful diving in a healthy man with a normal chest radiograph. Subpleural blebs were discovered on incidental CT scan several years later.

Pulmonary barotrauma in divers often occurs in the provocative setting of uncontrolled ascent, with rapid gas expansion and the potential for high transthoracic pressures.^6,7 It is estimated that a normal lung will rupture if a transtracheal pressure of 75–80 mm Hg is exceeded, and pulmonary structural predisposition is not needed to explain such incidents.^8,9 Prevention of such cases should focus on psychological suitability for underwater …