title: Finger volume pulse waveforms facilitate reliable assessment of heart rate variability, but not blood pressure variability or baroreflex function.
abstract: BACKGROUND
  We sought to determine whether heart rate variability (HRV), blood pressure (BP) variability, and baroreceptor-heart rate reflex sensitivity can be reliably assessed using finger volume pulse waveforms obtained from the commercially available EndoPAT device.
  
  
  METHODS
  Non-invasive BP (Finometer Pro as a non-invasive standard) and finger volume (EndoPAT) waveforms were recorded in 65 adults (37 ± 14 years; 60% female) and systolic BP and heart rate (HR) time series were derived after calibrating the EndoPAT signal based on systolic and diastolic BP values obtained by a sphygomomanometer. Transfer function analyses were performed to test for coherence between systolic BP and HR time series derived from the Finometer and EndoPAT devices. Time-domain HRV parameters, frequency domain HR and systolic BP variability parameters, and baroreflex sensitivity (sequence technique) were computed from Finometer- and EndoPAT-derived time series and intraclass correlation coefficients (ICC) were calculated.
  
  
  RESULTS
  Squared coherence between systolic BP time series derived from the Finometer and EndoPAT devices was low, suggesting poor correlation. In contrast, squared coherence between HR time series derived from the two devices was excellent [High Frequency (HF) = 0.80, Low Frequency (LF) = 0.81], with gain values close to 1.0. ICC values for time- and frequency-domain HRV parameters were excellent (>0.9 except for relative HF HRV, which was 0.77), while ICC values for frequency-domain BP variability parameters and baroreceptor-HR reflex sensitivity were low.
  
  
  CONCLUSIONS
  Finger volume pulse waveforms can be used to reliably assess both time-domain and frequency-domain HR variability. However, frequency domain BP variability parameters cannot be reliably assessed from finger volume pulse waveforms using the simple calibration technique used in this study.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Linder
authors.forename: Harald M
authors.initials: HM
authors.lastname: Stauss
authors.forename: Holly
authors.initials: H
authors.lastname: Gindes
authors.forename: Gary L
authors.initials: GL
authors.lastname: Pierce
authors.forename: Nicholas H
authors.initials: NH
authors.lastname: Von Bergen
authors.forename: William G
authors.initials: WG
authors.lastname: Haynes
authors.affiliation: Department of Internal Medicine, The University of Iowa, Iowa City, IA 52242, USA. jess-fiedorowicz@uiowa.edu.
authors.forename: Jess G
authors.initials: JG
authors.lastname: Fiedorowicz
mesh_terms: D000328:Adult; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D005260:Female; D005385:Fingers / Q000098:blood supply*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010991:Plethysmography / Q000379:methods*; D063177:Pulse Wave Analysis