title: Short-term pulse rate variability is better characterized by functional near-infrared spectroscopy than by photoplethysmography.
abstract: Pulse rate variability (PRV) can be extracted from functional near-infrared spectroscopy (fNIRS) (PRV(NIRS)) and photoplethysmography (PPG) (PRV(PPG)) signals. The present study compared the accuracy of simultaneously acquired PRV(NIRS) and PRV(PPG), and evaluated their different characterizations of the sympathetic (SNS) and parasympathetic (PSNS) autonomous nervous system activity. Ten healthy subjects were recorded during resting-state (RS) and respiratory challenges in two temperature conditions, i.e., room temperature (23°C) and cold temperature (4°C). PRV(NIRS) was recorded based on fNIRS measurement on the head, whereas PRV(PPG) was determined based on PPG measured at the finger. Accuracy between PRV(NIRS) and PRV(PPG), as assessed by cross-covariance and cross-sample entropy, demonstrated a high degree of correlation (r > 0.9), which was significantly reduced by respiration and cold temperature. Characterization of SNS and PSNS using frequency-domain, time-domain, and nonlinear methods showed that PRV(NIRS) provided significantly better information on increasing PSNS activity in response to respiration and cold temperature than PRV(PPG). The findings show that PRV(NIRS) may outperform PRV(PPG) under conditions in which respiration and temperature changes are present, and may, therefore, be advantageous in research and clinical settings, especially if characterization of the autonomous nervous system is desired.
authors.affiliation: University of Zurich, Department of Psychiatry, Psychotherapy, and Psychosomatics, Hospital of Psychiatry, Lenggstrasse 31, 8032 Zurich, Switzerland.
authors.forename: Lisa
authors.initials: L
authors.lastname: Holper
authors.affiliation: University of Zurich, Department of Psychiatry, Psychotherapy, and Psychosomatics, Hospital of Psychiatry, Lenggstrasse 31, 8032 Zurich, Switzerland.
authors.forename: Erich
authors.initials: E
authors.lastname: Seifritz
authors.affiliation: University Hospital Zurich, University of Zurich, Biomedical Optics Research Laboratory, Department of Neonatology, Frauenklinikstrasse 10, 8091 Zurich, Switzerland.
authors.forename: Felix
authors.initials: F
authors.lastname: Scholkmann
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D017156:Photoplethysmography / Q000379:methods*; D012372:ROC Curve; D012815:Signal Processing, Computer-Assisted; D019265:Spectroscopy, Near-Infrared / Q000379:methods*