Analysis of a microcirculatory windkessel model using photoplethysmography with green light: A pilot study

TL;DR

This pilot study introduces a green-light photoplethysmography method integrated into eyeglasses to quantify vasomotion and microcirculatory dynamics, validated by a windkessel model aligning with measured blood flow changes.

Contribution

It presents a novel wearable vasomotion measurement technique combining green light spectroscopy with a microcirculatory windkessel model for the first time.

Findings

Model predictions agree with measured blood flow data

The method effectively captures vasomotion during exercise and wind impact

The approach enables non-invasive assessment of autonomic control

Abstract

In this study, a vasomotion quantification method using a photoplethysmography prototype, which performs near-infrared spectroscopy in combination with green light, is proposed. A structure that suppresses the motion artifact and that is held by the eyeglasses on the back of the ear enables the relative concentration changes of total hemoglobin and pulse wave amplitude to be measured during exercise with and without the presence of wind impacting the face. We established a microcirculatory windkessel model including arteriovenous anastomoses estimated from the blood flow changes in the depth direction that were acquired using three wavelengths of light and reproduced the vasomotion on a computer. The values predicted by the model were in good agreement with the measured values. The extracted vasomotion can be used to understand autonomic control by the central nervous system.