Diffuse transmittance spectroscopy for ultra short-term measurement of pulse rate variability in healthy subjects

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 328; p. 125456
• Main Author: Bachir, Wesam
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 05.03.2025
• Subjects: Adult; Diffuse transmittance; Female; Healthy Volunteers; Heart Rate - physiology; Humans; Male; Oximetry - methods; Photoplethysmography; Photoplethysmography - methods; Plethysmography - methods; Pulse rate variability; Signal Processing, Computer-Assisted; Spectroscopy; Spectrum Analysis - methods; Young Adult; Pulse rate variability; Spectroscopy; Photoplethysmography; Diffuse transmittance
• ISSN: 1386-1425; 1873-3557
• DOI: 10.1016/j.saa.2024.125456

[Display omitted] •Novel diffuse transmittance spectroscopic approach for pulse rate variability measurements•Extending the existing applications of diffuse transmittance spectroscopy through integrating pulse rate variability•Possibility of multi-wavelength measurements using simple optical setup in comparison with conventional diodes and photodiodes•Potential measurement of pulse rate variability in the visible range of the spectrum•Miniaturizing the optical setup is a potential possibility for wearable biosensors Multi-wavelength plethysmography (MWPPG) is a growing technique for noninvasive hemodynamic measurements, particularly spectral based methods. Different wavelengths have been investigated for both transmissive and reflectance PPG configurations. The objective of this work is to investigate the feasibility of Diffuse Transmittance Spectroscopy (DTS) for Pulse Rate Variability (PRV) measurements and to evaluate the performance of diffuse transmittance spectroscopy in quantifying ultrashort pulse rate variability. DTS was used for reconstructing PPG signal followed by PRV analysis. DTS and reference PPG recordings were acquired from 18 healthy subjects in total. PRV features include time-domain, and frequency-domain features are extracted from 50 s duration. The extracted PRV parameters were compared to PRV parameters derived from conventional pulse oximetry-based PPG. Pulse rate variability analysis was applied on DTS and reference PPG tracings. The comparison demonstrated a strong correlation between the diffuse transmittance spectral method and the gold standard PPG sensor. Significant correlation (r > 0.90, p < 0.05) was found between PRV from DTS and reference PRV for mean intervals, standard deviation of intervals (SDNN) and the root-mean square of the difference of successive intervals (RMSSD). A good agreement was found between PRV Parameters in time domain of PPG analysis using Bland–Altman plots with 95 % limits of agreements. However, Bland-Altman analysis showed a considerable divergence in frequency parameters. The study also revealed that PPG based diffuse transmittance measurements were insensitive to ambient noise in comparison with conventional pulse oximeter. The results suggest a potential application of the diffuse transmittance spectroscopy for pulse rate variability analysis.