Baroreflex regulation measurement using a noninvasive laser Doppler method

In this study, a noninvasive laser Doppler measurement method based on the self-mixing effect of a diode laser was used to measure baroreflex regulation, which is manifest in the blood pressure signal as a 0.1 Hz sinusoidal variation. The laser Doppler measurement system was used to measure the movement of the right radial artery of ten volunteers. Variation in blood pressure caused by the baroreflex affects the elastic properties of the arterial wall. When diastolic blood pressure increases, the elasticity of the arterial wall decreases, causing the wall to lose some of its movability. This decreased elasticity reveals itself in the Doppler signal such that when the blood pressure increases, the Doppler frequency decreases and vice versa. The results show, that the laser Doppler method can be used to measure baroreflex regulation. Finally, baroreflex regulation in the Doppler signal is approximately in the inverse phase with respect to variation in diastolic blood pressure.