Pulmonary barotrauma in divers during emergency free ascent training: review of 124 cases.

INTRODUCTION Experience from treating diving accidents indicates that a large proportion of divers suffering from pulmonary barotraumas (PBT) or arterial gas embolism (AGE) were engaged in training dives, specifically emergency free ascent (EFA). We tried to verify this relationship and to calculate, if possible, the risk associated with normal recreational dives, training dives, and EFA training dives. METHODS All diving accidents treated at the Centre for Hyperbaric Oxygen Therapy (Brussels, Belgium) from January 1995 until October 2005 were reviewed. Data on the average number of dives performed and the proportion of in-water skills training dives were obtained from the major Belgian dive associations. RESULTS A total of 124 divers were treated, of whom 34 (27.4%) were diagnosed with PBT. Of those, 20 divers (58.8%) had symptoms of AGE. In 16 of those, EFA training exercise was deemed responsible for the injury. The association between EFA training and PBT proved to be very significant, with an odds ratio of 11.33 (95% confidence interval: 2.186 to 58.758). It was possible to calculate that a training dive (0.456 to 1.36/10,000) carries a 100 to 400 times higher risk, and an ascent training dive (1.82 to 5.46/10,000 dives) a 500 to 1500 times higher risk for PBT than a non-training dive (0.0041 to 0.0043/10,000 dives). DISCUSSION This study confirms a significant association between EFA training dives and the occurrence of PBT.