Risk factors for pulmonary barotrauma in divers

Pulmonary barotrauma (PBT) of ascent is a feared complication in compressed air diving. Although certain respiratory conditions are thought to increase the risk of suffering PBT and thus should preclude diving, in most cases of PBT, risk factors are described as not being present. The purpose of our study was to evaluate factors that possibly cause PBT.

We analyzed 15 consecutive cases of PBT with respect to dive factors, clinical and radiologic features, and lung function. They were compared with 15 cases of decompression sickness without PBT, which appeared in the same period.

Clinical features of PBT were arterial gas embolism (n=13), mediastinal emphysema (n=1), and pneumothorax (n=1). CT of the chest (performed in 12 cases) revealed subpleural emphysematous blebs in 5 cases that were not detected in preinjury and postinjury chest radiographs. A comparison of predive lung function between groups showed significantly lower midexpiratory flow rates at 50% and 25% of vital capacity in PBT patients (p<0.05 and p<0.02, respectively).

These results indicate that divers with preexisting small lung cysts and/or end-expiratory flow limitation may be at risk of PBT.