Two-Cuff Noninvasive Blood Pressure Waveform Monitoring System for Dynamic Blood Vessel Characteristic Study

This study proposes and constructs a two-cuff non-invasive blood pressure waveform monitor system. The proposed system uses dynamic feedback to maintain constant low cuff pressure at 40 mmHg. Thus, long term continuous blood pressure waveform monitoring is possible. Additionally, the two blood pressure waveforms can be used to compute the system function, frequency response and impulse response of vessel system for system dynamic studies. Ten normal young males were recruited for this study. Continuous blood pressure signals from upper arm and wrist were obtained by the proposed system. During steady state, correlation coefficients of systolic pressure and diastolic pressure, between upper arm and wrist, are 0.83plusmn0.15 and 0.81plusmn0.14, respectively. During cold pressor, correlations decrease slightly. Additionally, the blood vessel system model was evaluated using autoregressive exogenous model (ARX) model. The dynamic changes of blood vessel system during task can be seen from the 3D time-varying impulse responses. In order to assist the observation of the dynamic characteristic change of blood vessel system during different physiological conditions, the 90% energy curve was proposed and used. Before the end of cold pressor, the 90% energy curve reviewed that system energy accumulates faster than steady state indicating the vessel system shifted to higher frequency. On the other hand, the system shifted to slower system during Valsalva maneuver