Effects of fluid loss on the physiology of closed-circuit rebreather divers after 100- and 45-metre dives.

INTRODUCTION

Diving induced immersion diuresis predisposes divers to dehydration. Dehydration is considered a risk factor for decompression sickness (DCS) but there is very little evidence to prove it. Dehydration also potentially modifies venous gas emboli (VGE) formation and impairs endothelial function. The purpose of this study was to report the effects of fluid loss during a dive on the diver's physiology.

METHODS

Nine divers performed a 45 metre fresh water (mfw) and a 100 mfw dive with predetermined dive profiles. Body weight was measured before and after the dive. Post-dive detection of VGE was performed according to the extended Eftedal-Brubakk scale. We also measured haematocrit and flow mediated dilation before and after the 100 mfw dives.

RESULTS

After a 68-minute dive to 45 mfw, median weight loss was -1.1 kg, (IQR -1.2, -1.0; range -2.0, -0.6), P = 0.009 and VGE were detected in all divers. After a 170-minute dive to 100 mfw, median weight loss was -1.5 kg (IQR -1.8, -1.1; range -2.2, -0.8), P = 0.009 and VGE were detected in seven divers. Weight loss after the dive was statistically significant and there was a negative correlation between weight loss and bubbling after the 45 mfw dives. None of the divers suffered any symptoms of DCS.

CONCLUSIONS

We found significant weight loss after both decompression dives but there were no clinical DCS symptoms in any of the divers. This study does not offer new evidence supporting the notion that dehydration increases decompression stress in divers.