Motion-compensated noncontact imaging photoplethysmography to monitor cardiorespiratory status during exercise

Yu Sun

doi:10.1117/1.3602852

Abstract

With the advance of computer and photonics technology, imaging photoplethysmography [(PPG), iPPG] can provide comfortable and comprehensive assessment over a wide range of anatomical locations. However, motion artifact is a major drawback in current iPPG systems, particularly in the context of clinical assessment. To overcome this issue, a new artifact-reduction method consisting of planar motion compensation and blind source separation is introduced in this study. The performance of the iPPG system was evaluated through the measurement of cardiac pulse in the hand from 12 subjects before and after 5 min of cycling exercise. Also, a 12-min continuous recording protocol consisting of repeated exercises was taken from a single volunteer. The physiological parameters (i.e., heart rate, respiration rate), derived from the images captured by the iPPG system, exhibit functional characteristics comparable to conventional contact PPG sensors. Continuous recordings from the iPPG system reveal that heart and respiration rates can be successfully tracked with the artifact reduction method even in high-intensity physical exercise situations. The outcome from this study thereby leads to a new avenue for noncontact sensing of vital signs and remote physiological assessment, with clear applications in triage and sports training.

Highlights

The peripheral pulse acquired from photoplethysmography (PPG) can provide information about cardiovascular status, such as blood oxygen saturation, heart and respiration rates, cardiac output, and blood pressure.[1]
analysis of variance (ANOVA) showed a significant influence of exercise on systolic blood pressure (SBP) and heart rate (HR) (F = 7.608, p = 0.001 and F = 12.666, p < 0.001)
Posthoc tests revealed that, compared to the rest condition, the HR and SBP were significantly higher than baseline after both exercise levels

Summary

Introduction

The peripheral pulse acquired from photoplethysmography (PPG) can provide information about cardiovascular status, such as blood oxygen saturation, heart and respiration rates, cardiac output, and blood pressure.[1]. It has been demonstrated that the springloaded clips in conventional cPPG finger probes will affect the waveform of PPG signals due to the contact force between the sensor and the measurement site.[3] One potential way to overcome this problem is through the use of imaging PPG (iPPG), a remote, contactless diagnostic technique that can assess peripheral blood perfusion.[4,5,6,7]. Wieringa et al have introduced a multiple wavelength imaging PPG device that provides a potential route toward contactless blood oxygen saturation assessment,[5] and Verkruysse et al have reported a remote PPG signal acquisition technique based on a digital camera and using ambient light illumination.[6] we have previously presented an integrated imaging PPG setup for the detection of tissue optophysiological properties.[11] Recent progress in iPPG research activities has stimulated our interest in the remote assessment of the cardiovascular system for evaluation of the influence of exercise

Methods

Results

Discussion

Conclusion