Synthetic photoplethysmography (PPG) of the radial artery through parallelized Monte Carlo and its correlation to body mass index (BMI)

Tananant Boonya-ananta,Anders K. Hansen,Vinh Nguyen Du Le,Jessica C. Ramella-Roman,Joshua D. Hutcheson,Ajmal Ajmal,Andres J. Rodriguez

doi:10.1038/s41598-021-82124-4

Tananant Boonya-ananta, Anders K. Hansen + Show 5 more

Open Access

https://doi.org/10.1038/s41598-021-82124-4

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Abstract

Cardiovascular disease is one of the leading causes of death in the United States and obesity significantly increases the risk of cardiovascular disease. The measurement of blood pressure (BP) is critical in monitoring and managing cardiovascular disease hence new wearable devices are being developed to make BP more accessible to physicians and patients. Several wearables utilize photoplethysmography from the wrist vasculature to derive BP assessment although many of these devices are still at the experimental stage. With the ultimate goal of supporting instrument development, we have developed a model of the photoplethysmographic waveform derived from the radial artery at the volar surface of the wrist. To do so we have utilized the relation between vessel biomechanics through Finite Element Method and Monte Carlo light transport model. The model shows similar features to that seen in PPG waveform captured using an off the shelf device. We observe the influence of body mass index on the PPG signal. A degradation the PPG signal of up to 40% in AC to DC signal ratio was thus observed.

Highlights

Elevated blood pressure (BP) is considered one of the highest risk factors for cardiovascular disease
Invasive arterial line blood pressure measurement is often used in the Intensive Care Unit (ICU), where an arterial catheter is placed inside the radial artery of a patient to directly measure vessel internal pressure[15,16]
We have focused on dynamics and biomechanical behavior of a large vessel, the radial artery, deeper and larger in physiology past thin blood layer contained in the dermis

Summary

Introduction

Elevated blood pressure (BP) is considered one of the highest risk factors for cardiovascular disease. Research into cuff-less and continuous BP devices based on photoplethysmography (PPG) is rapidly expanding These systems provide unique diagnostic opportunities, such as monitoring of nocturnal hypertension[10] a condition strongly associated with cardiovascular events and organ damage. The pressure profile inside the arteries changes as the pressure wave propagates downstream from the heart to peripheral vasculature[19,20,21]. The dicrotic notch moves further away from the systolic peak as arterial line measurement location moves further down the arterial tree. Another mechanism which has been noted to influence PPG signals is optical scattering caused by time-variant red blood cell (RBC) aggregation[22,23]. In vessels of this size, the vessel diameter is large compared to cell size and fluid can be approximated as a Newtonian fluid[25,26] and flow can be modeled as a homogenous fluid[27] flow

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