Ambiguity of mapping the relative phase of blood pulsations.

Victor Teplov,Rashid Giniatullin,Alexander A Makarenko,Alexei A Kamshilin,Ervin Nippolainen

doi:10.1364/boe.5.003123

Abstract

Blood pulsation imaging (BPI) is a non-invasive optical method based on photoplethysmography (PPG). It is used for the visualization of changes in the spatial distribution of blood in the microvascular bed. BPI specifically allows measurements of the relative phase of blood pulsations and using it we detected a novel type of PPG fast waveforms, which were observable in limited areas with asynchronous regional blood supply. In all subjects studied, these fast waveforms coexisted with traditional slow waveforms of PPG. We are therefore presenting a novel lock-in image processing technique of blood pulsation imaging, which can be used for detailed temporal characterization of peripheral microcirculation.

Highlights

The non-invasive optical method, photoplethysmography (PPG), is a traditional and widely used approach allowing the detection of blood volume changes in the peripheral tissues of the body [1,2]
Blood Pulsation Imaging (BPI) allows measurements of the relative phase of blood pulsations and using it we detected a novel type of PPG fast waveforms, which were observable in limited areas with asynchronous regional blood supply
By comparing the calculated spatial distributions of blood pulsation phase (BPP) with the relative phase between PPG waveforms measured in different regions of interest (ROI), we found that the shape of the reference function could be used for a more reliable BPP mapping

Summary

Introduction

The non-invasive optical method, photoplethysmography (PPG), is a traditional and widely used approach allowing the detection of blood volume changes in the peripheral tissues of the body [1,2]. Conventional PPG devices such as the pulse oximeter provide measurements only in a single point To overcome this limitation several research groups reported the development of an imaging system for remote oximetry based on the reflection-mode PPG and operating under illumination at two or more wavelengths [8,9,10]. In these systems a two-dimensional (2D) photosensitive matrix is used instead of a single photoreceiver. As we more recently showed [13], the relative phase of blood pulsations is a very important channel of biomedical information. As the BPI method is new, the reliability of the blood pulsation phase (BPP) measurements needs to be further improved

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Conclusion