NEW ALGORITHM FOR EVALUATING CARDIO RESPIRATORY SYNCHRONIZATION UNDER ZEN MEDITATION AND VARIOUS MENTAL-STRESS STATES

Background This paper presents new graphical algorithms for illustrating the efficiency of cardio respiratory interactions at different levels of mental stress. Methods Seven, Zen-meditation practitioners (experimental group) and fifteen normal controls at different levels of mental stress were studied. Synchrogram analysis based on the relationship between R-peak phase and respiratory cycle can access the performance of cardio respiratory interactions. Ranked R-peak phase alignment (RRPA) and R-peak linearization (RPL) synchrogram proposed in this study provide a long-term overview of the quality and performance of cardio respiratory functioning and respiratory sinus arrhythmia (RSA) performance. RRPA characterizes the global behavior of R-peak phases of the synchrogram by linear regression of ranked R-peak phases. RPL synchrogram provides another overview of the RSA behavior. RPL synchrogram is composed of piecewise linear lines formed by linear regression of the normalized R-peak phases in one respiratory cycle. Time-domain HRV (heart rate variability) and RSA are evaluated as the referenced indicators. Results HRV and RSA analysis shows breathing regulation at 8 breaths per minute effectively relieves the mental stress. The effect of breathing regulation is better than the normal relaxation rest. Zen-meditation practitioners exhibit prominently better performance on cardio respiratory synchronization and RSA behavior. Zen meditation induces a better regulation scheme for stabilizing the cardio respiratory functioning Conclusions RRPA portrait makes the cardio respiratory synchronization behavior more visible than conventional synchrogram. The deviation of the first and the last R-peak phases in different respiratory cycles allow us to track the regularity and stability of cardio respiratory interactions.