Bio‐Optics: Optical Measurement of Pulse Wave Transit Time

Abstract

The arterial blood pressure has long been known as one of the most important medical factors reflecting the state of the cardiovascular system. A useful and convenient parameter for continuous monitoring of blood pressure is pulse wave velocity or pulse wave transit time (PWTT) between different regions of human body. It is suggested that, although it may be difficult to estimate systolic blood pressure from PWTT with acceptable accuracy, possibilities still remain to use changes of pulse arrival time as an indicator of changes in systolic blood pressure. During the exercise, arterial blood pressure increases, which is mainly achieved by increasing the contractility of the heart and vasculature resistance. Both of these values result in the increase of pressure wave speed in the vascular system, which means that the time delay between the start of electromechanical contraction and PWTT to any particular point in the body decreases. In our previous studies, we have shown that it is possible to calculate the mean arterial pressure from pulse wave transit time.

Estimation of pulse transit time using time delay estimation techniques

“…An acute rise in BP causes vascular tone to increase and hence the arterial wall becomes stiffer which causes PTT to shorten. The PTT has clinically significant association with systolic hypertension at a given time, but PTT enables predicting changes in BP over a short period [3]. PTT can be measured by recording the time interval between passages of arterial pulse wave at any two consecutive arterial points or time interval between the dual mode PPG signals recording from earlobe and finger [4,5].…”