411 / 2022-07-22 12:44:54

Estimation of Transfer Function between Brachial Arterial Blood Pressure and Cuff Oscillometric Signal in Blood Pressure Measurement using Cardiovascular Simulator

Short-time Fourier transform,Transfer function,Oscillometric signal,Blood pressure waveform

Special Sessions > Human Vibration and Health Sensor Applications

Oscillometric blood pressure measurement is mainly used to diagnose cardiovascular health conditions. In addition to the systolic and diastolic blood pressure values, arterial blood pressure waveforms also contain a lot of information on cardiovascular health conditions. In this study, a simulator mimicking human cardiovascular system was used to model the relationship between the brachial arterial pressure wave and the oscillometric signal [1]. An upper arm phantom made of silicone was installed in this simulator to reproduce the oscillometric blood pressure measurement process, and the brachial arterial pressure and the cuff pressure were measured simultaneously. It is assumed that the oscillometric signal and brachial arterial pressure have a nonlinear relationship, but have a linear relationship when the mean cuff pressure is fixed. Using the simulator, the brachial arterial pressure waves were set to have a minimum value of 80 mmHg and a maximum value of 120 mmHg, and the oscillometric signals for each frequency were measured through sine sweep method from 0.5 Hz to 9.0 Hz. The transfer function values between arterial pressure waves and cuff oscillometric wave for each mean cuff pressure were obtained using Short-time Fourier transform. The result shows that where the mean cuff pressure is 120 mmHg or less, the size difference of the transfer function by frequency component is quite large, but where the mean cuff pressure is 120 mmHg or more, the size difference of the transfer function by frequency component is relatively small. Through the dynamic model obtained through the experiment, it was possible to reproduce the virtual oscillometric signal according to the heart rate through numerical simulation. The waveforms in the oscillometric signal according to the cuff pressure significantly changed as the heart rate of the brachial arterial pressure increased. In addition, as the heart rate increased, the maximum amplitude of the oscillometric signal decreased. It would be possible to predict the oscillometric signal using the transfer function according to the waveform and the heart rate of brachial arterial pressure.