Preventive measures to reduce the risk of
decompression sickness can involve several procedures such as
oxygen breathing during in-water
decompression. Theoretical predictions also suggest that brief periods of recompression during the course of
decompression could be a method for controlling bubble formation. The aim of this study was to get clearer information about the effects of different experimental ascent profiles (EAPs) on bubble reduction, using pure
oxygen or recompression during
decompression for
nitrox diving. Four EAPs were evaluated using bubble monitoring in a group of six military divers using
Nitrox 40% O(2) breathing with a rebreather. For EAP 1 and 2, 100% O(2) was used for the end stage of
decompression, with a 30% reduction of
decompression time in EAP 1 and 50% in EAP 2, compared to the French navy standard schedule. For EAP 3 and 4,
nitrox 40% O(2) was maintained throughout the
decompression stage. EAP 3 is based on an air standard
decompression schedule, whereas EAP 4 involved a brief period of recompression at the end of the stop. We found that EAP 1 significantly reduced bubble formation, whereas high bubble grades occurred with other EAPs. No statistical differences were observed in bubbles scores between EAP 3 and 4. One diver developed mild neurological symptoms after EAP 3. These results tend to demonstrate that the "
oxygen window" plays a key role in the reduction of bubble production and that breathing pure
oxygen during
decompression stops is an optimal strategy to prevent
decompression sickness for
nitrox diving.