Effects of Hyperbaric Exposure on the Cardiovascular System. Role of the Autonomous Nervous System

Introduction Among experienced divers, dive adaptation is seen as a modified pattern of physiological changes. This is reflected, inter alia, in the change in cardiovascular responses, therefore there is need to examine the role of the autonomic nervous system in cardiovascular response modulation after hyperbaric exposure. Material and methods Ten experienced divers took part in the study. The effects of hyperbaric exposure at 30 and 60 meters and interaction (depth x time) were measured. Changes in HR, RRI, CI and HRV values have been taken into analysis. Results Hyperbaric exposure at 30 meters significantly affected HFnu-RRI elevation and decrease of LFnu-RRI (F = 42.92, p <0.00001), without significant affecting the HR, RRI and CI. Exposure to hyperbaric 60 m increased HR and CI (F = 7.64, p = 0.01 and F = 4.89, p = 0.04 respectively) and RRI (F = 7.69, p = 0.01), without significant impact on other variables. The influence of interaction (depth x time) was significant in all measured variables. Conclusions The results indicate that hyperbaric exposure at 60 meters affected HR, RRI, CI parameters, that were not significantly affected by hyperbaric exposure at 30 meters. On the other hand, the exposure at 30 meters showed a significant effect on the LFnu and HFnu HRV, which were not significantly affected by the exposure at 60 meters. Significant effect of time and depth interaction in each of the analyzed variables was observed.