Facial Remote Photoplethysmography for Continuous Heart Rate, Stroke Volume, and Systemic Vascular Resistance Monitoring During Prolonged Warm/Cold Fluid Bolus Administration

Hemodynamic parameters—stroke volume (SV), systemic vascular resistance (SVR), and heart rate (HR)—are critical for clinical monitoring, particularly in emergency and critical care settings. This study evaluates the feasibility of a noninvasive, noncontact monitoring approach using imaging photoplethysmography (iPPG), which applies camera-based PPG and a signal processing pipeline implemented in MATLAB. A total of 25 prolonged video recordings (2500 min) were collected from 16 healthy volunteers at Odense University Hospital, while they received intravenous infusions of warm (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$37~^{\circ }$ </tex-math></inline-formula>C) and cold (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$15~^{\circ }$ </tex-math></inline-formula>C) Ringer’s lactate. To ensure data reliability, video quality and head motion were systematically analyzed. HR estimation using the plane-orthogonal-to-skin (POS) method achieved an average absolute error (avAE) of 4.28 bpm, with the best accuracy of 2.18 bpm, while the CHROM method yielded similar performance (4.27-bpm average error and 2.55-bpm best accuracy). SV and SVR demonstrated moderate correlation with reference measures (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${r} = {0.571}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${r} = {0.596}$ </tex-math></inline-formula>, respectively) across five regions of interest. The best correlations for SV and SVR were <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${r} = {0.846}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${r} = {0.873}$ </tex-math></inline-formula>, respectively, indicating strong potential for accurate noncontact monitoring. These results suggest that iPPG can provide real-time cardiovascular insights during fluid therapy, with potential applications in telemedicine and mobile health. However, to robustly generalize the findings of this study, limitations such as interindividual variability and the need to include diverse patient populations should be considered. This study provides the first demonstration of iPPG feasibility for prolonged emergency fluid administration, paving the way for further research in dynamic clinical environments.