Tracking EEG changes during the exposure to hyperbaric oxygen.

Objective: The aim was to investigate and define possible alterations in cerebral activity during prolonged hyperbaric oxygen exposure and decompression as compared to baseline activity.

Methods: Thirty-two channel electroencephalography (EEG) was recorded with a Bluetooth EEG system in 11 subjects. A 20-min EEG recording was carried out under three different conditions: breathing air inside a hyperbaric chamber at sea level; breathing oxygen at a simulated depth of 18 msw; breathing air at sea level after decompression. Relative EEG power was estimated in frequency ranges.

Results: During oxygen breathing, brain activity showed an early fast delta decrease in the posterior regions, with a synchronous and significant increase in alpha in the same regions. After decompression, the delta relative power decrease was uniformly distributed over the cerebral cortex until minute 8, and the alpha relative power was maximal in the posterior regions during the first 2 min.

Conclusions: These results may be relevant for establishing a reference point in future studies on oxygen-sensitive subjects who reported problems during oxygen diving.

Significance: Significant changes in EEG relative power suggest that it may be possible to define and recognize landmarks of oxygen-induced brain activity, which would be useful in the medical treatment of subjects reporting "oxygen-toxicity diving-related problems".