A Study on the Correlation between Arterial Pressure, Pulse Transit Time and Other Time-Domain Characteristic Parameters of Radial Pulse Wave

Non-invasive beat-to-beat blood pressure monitoring is of great meaning in both health assessment and disease treatment. Pulse transit time (PTT) method is potentially the best indirect blood pressure (BP) estimation method since it is comfortable, economical and needs no supervisor. However, the PTT method has two major defects. Firstly, PTT calculated in traditional ways includes the pre-ejection period (PEP) which is irrelevant to BP. In this paper, we define PTT as the time interval between two pulse waves obtained from elbow and wrist, and correlation coefficients were employed to quantify the relationship between BP and PTTs which are computed in different ways. Another problem of PTT method is that the relationship between PTT and BP is not consistent but depends on the status of cardiovascular system, making continuous recalibration a necessity for long time BP monitoring. To solve this problem, 28 time-domain features are extracted from the pulse waveform and their correlations with BP are analyzed to find out whether they are possible to reflect the status of cardiovascular system. The result shows that PTTs excluding PEP have better correlations with BP than those computed in traditional ways. Significant correlations are also observed among BP and several pulse wave features, which suggests that these features are potentially useful in enhancing the performance of PTT method in future work.