Assessment of the phase relationship between breathing, heart rate and blood pressure by the modified complex demodulation

This work is part of a study which investigates the short term control of the cardiovascular system by the autonomous nervous system. The authors present a method to investigate the phase relationship between the blood pressure oscillations and heart rate and breathing at different frequencies and volumes. The modified complex demodulation analysis allows for a continuous evaluation of the phase shift. Phase shift changes at the different experimental conditions are observed.