Spontaneous fluctuation in the tissue blood volume and the systolic blood volume increase

The tissue blood volume and the systolic blood volume increase can be measured, in relative terms, by means of photoplethysmography-the measurement of the absorption of light by the blood. The values of the blood volume and the systolic blood volume increase fluctuate due to the fluctuating intensity of the autonomic nervous system activity. In this study, these fluctuations were investigated. Positive correlation was found between the blood volume and the systolic blood volume increase and negative correlation between the latter two and arterial blood pressure.