Effect of ambient lighting and skin tone on estimation of heart rate and pulse transit time from video plethysmography

Research output: Chapter in Book/Report/Conference proceedingConference proceeding contribution

Abstract

Video-based photoplethysmography (vPPG) enables remote and contactless detection of the peripheral pulse of blood flow. This provides a potential mean to extract heart rate (HR) and pulse transit time (PTT) for the purpose of remote health monitoring. The accuracy of average HR and PTT extracted from a two-minute vPPG recording has been investigated at six different lighting conditions among participants with a range of Fitzpatrick skin scores. 12 healthy volunteers (6 females, 27 ± 6 years) were recruited. The video, electrocardiogram and finger PPG were acquired from immobile resting subjects. The vPPG signals from red, green and blue channels, and a combination of those were investigated. The vPPG signals were extracted from two regions of interest (ROIs): one on the forehead and one on the palm of the left hand. The estimated HR error (HR-error) was significantly lower for vPPG from green channels in both ROIs (ROI1 [p<0.001], ROI2 [p<0.05]). The signal from ROI1 demonstrated lower HR-error than ROI2 (p<0.001). HR-error from the darkest lighting conditions (Lumen 1 and 2) were significantly higher than the others (p<0.05). Furthermore, HR-error showed a positive correlation with skin tone scores in every lighting condition. However, at brighter lighting intensity, HR-error was independent of the skin tone score. PTT calculated from vPPG (vPTT) were compared between the 6 levels of lightings and the result was significantly different (p<0.05). In darker lighting conditions, the vPTT increased. Pulse arrival time measured from PPG (PAT-PPG) was calculated, and a positive correlation was found between the ratio of vPTT/PAT-PPG and skin tone score at six different lightings. However, this dependency decreases in brighter lighting intensity. These results suggest that HR-error and the ratio of vPTT/PAT increase with darker skins and at darker backgrounds. However, at brighter lighting conditions, the skin tone score is not a confounder of vPPG accuracy.

Original languageEnglish
Title of host publication42nd Annual International Conferences of the IEEE Engineering in Medicine and Biology Society
Subtitle of host publicationEnabling Innovative Technologies for Global Healthcare, EMBC 2020
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
Pages2642-2645
Number of pages4
ISBN (Electronic)9781728119908
ISBN (Print)9781728119915
DOIs
Publication statusPublished - 1 Jul 2020
Event42nd Annual International Conferences of the IEEE Engineering in Medicine and Biology Society, EMBC 2020 - Montreal, Canada
Duration: 20 Jul 202024 Jul 2020

Publication series

NameProceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS
Volume2020-July
ISSN (Print)1557-170X

Conference

Conference42nd Annual International Conferences of the IEEE Engineering in Medicine and Biology Society, EMBC 2020
CountryCanada
CityMontreal
Period20/07/2024/07/20

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