Features of light modulation caused by a pulse wave of blood pressure
Natalia P. Podolyan, Mariya A. Asalkhanova, Timofey A. Efimov, Roman V. Romashko, Alexei A. Kamshilin; Institute of Automation and Control Processes of Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Russia
Abstract
The report discusses the features of the light modulation at the heart rate after the interaction of this light with living biological tissue in a reflective geometry. This modulation is the main parameter in imaging photoplethysmography (iPPG) systems, which makes it possible to quantify the dynamics of tissue perfusion changes. But until now, the iPPG signal generation model remains the subject of discussion. The report will present experimental studies comparing the waveforms of iPPG signals from the moistened upper layer of the skin obtained in three configurations: (a) without polarizing filtration, (b) with filtration by crossed linear polarizers, and (c) with filtration using a circular polarization filter. Studies have shown that the modulation of light on heart rate is the result of a complex interaction of two effects: ballystocardiographic (BCG) and photoplethysmographic. Polarizing filtration of both types (linear and circular) suppresses BCG under certain conditions and improves the stability of perfusion measurement. The observed features of the light modulation waveform can be explained if we take into account the periodically changing parameters (in unison with cardiac activity) of the microcirculatory network due to mechanical compression of this network by transmural pressure of nearby arterial vessels.
Speaker
Natalia Podolyan
Institute of Automation and Control Processes FEB RAS
Russia
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