Changes in human brainstem auditory evoked potentials during a 1,100 kPa He-O2 simulated saturation dive.

Four divers were chosen as subjects to conduct the 1,100 kPa He-O2 simulated saturation dive. Brainstem auditory evoked potentials of the divers were monitored during different stages of the exposure. At 1,100 kPa, with both 10 and 50 Hz clicks, interpeak latencies I-V were prolonged by 0.242 and 0.360 ms, respectively, indicating impedance of synaptic transmission. Results showed that interpeak latencies I-V were prolonged by 0.242 and 0.360 ms, respectively, indicating impedance of synaptic transmission. However, the latency of wave I was shortened by 0.11 ms, which was presumed to be due to different mechanical sound transmission velocity at hyperbaric helium environment. Interestingly, the latency of wave I prolonged gradually during hyperbaric exposure to 1,100 kPa. This might be used for the measurement of effects of hydrostatic pressure and He on the central nervous system (CNS). These changes coupled with easy perspiration and fatigue of the divers suggest that the pressure of the present experiment had certain effects of the CNS on the divers, although they were moderate and temporary.