Exploring Nonlinear Heart Rate Variability for Assessing the Autonomic Nervous System in Hyperbaric Environments

Underwater diving presents noteworthy physiological challenges, impacting the autonomic nervous system (ANS) balance. Heart Rate Variability (HRV) is a widely used tool for ANS assessment. While standard HRV methods are prevalent in diving research, nonlinear HRV methods are still not fully exploited. In this study, we characterized cardiac variability complexity in hyperbaric environments using nonlinear methods. We recorded ECG signals from 31 subjects in a dry hyperbaric chamber across different pressure stages. Significant changes were noted between baseline and return-to-surface conditions. The observed differences suggest that the inclusion of these parameters in standard HRV analysis could help in a better understanding of diving physiology and serve as a potential diagnostic marker for associated risks.