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Balance testing and Doppler monitoring during hyperbaric exposure
Stein H G Nordahl1, Torbjørn Aasen, Jan Risberg
1Department of Otolaryngology/Head and Neck Surgery, Haukeland University Hospital, Bergen, Norway. mail@fms.as
Background:
The effects on the postural system of saturation diving to shallow and medium depths have not previously been adequately tested. The purpose of this study was to investigate whether postural function is affected by a moderate hyperbaric exposure, and whether any deterioration is correlated with the presence of intravascular bubbles.
Hypothesis:
Postural control and the vestibulo-ocular reflex are not affected during heliox saturation diving to 5 meters of seawater (msw). At greater depths, an effect may occur.
Methods:
Postural control was tested with the subjects standing on a static balance platform before, during, and after onshore experimental saturation chamber dives to 5 msw heliox, 20 msw air, and to 100 msw heliox. Standard caloric testing with electronystagmography was performed before and after the heliox dives. Cardiac ultrasound and Doppler monitoring were used to detect possible venous gas emboli (VGE) during decompression in the heliox dives.
Results:
During the heliox exposure to 5 msw, no significant change in body sway was found. However, a significant change in body sway was found during an air dive to 20 msw and during the 100 msw heliox exposure. Caloric responses were unchanged immediately post-dive. After decompression from 5 msw, VGE were detected in two divers. During the 100 msw exposure, one case of VGE was observed.
Conclusions:
Exposure to hyperbaric heliox conditions corresponding to 5 msw, did not influence postural control significantly, while exposure to 100 msw heliox, and air diving to 20 msw, did. Although VGE were detected in the heliox dives, we could not find any correlation between this observation and postural instability.
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