Filtering-induced time shifts in photoplethysmography pulse features measured at different body sites: the importance of filter definition and standardization

Liu, Haipeng1; Allen, John1; Khalid, Syed Ghufran1; Chen, Fei2; Zheng, Dingchang1

2021-07-01

10.1088/1361-6579/ac0a34

PHYSIOLOGICAL MEASUREMENT   影响因子和分区

0967-3334

1361-6579

Objective. The waveform of a photoplethysmography (PPG) signal depends on the measurement site and individual physiological conditions. Filtering can distort the morphology of the original PPG signal waveform and change the timing of pulse feature points on PPG signals. We aim to quantitatively investigate the effect of PPG signal morphology (related to measurement site) and type of pulse feature on the filtering-induced time shift (TS). Approach. 60 s PPG signals were measured from six body sites (finger, wrist under (volar), wrist upper (dorsal), earlobe, and forehead) of 36 healthy adults. Using infinite impulse response digital filters which are common in PPG signal processing, PPG signals were prefiltered (band-pass, pass and stop bands: >0.5 Hz and <0.2 Hz for high-pass filter, 30 Hz for low-pass filter) and then filtered (low-pass, pass and stop bands: 5 Hz). Four pulse feature points were defined and extracted (peak, valley, maximal first derivative, and maximal second derivative). For each subject, overall TS and intra-subject TS variability in feature points were calculated as the mean and standard deviation of TS between prefiltered and filtered PPG signals in 50 cardiac cycles. Statistical testing was performed to investigate the effect of measurement site and type of pulse feature on overall TS and intra-subject TS variability. Main results. Measurement site, type of pulse feature, and their interaction had significant impacts on the overall TS and intra-subject TS variability (p < 0.001 for all). Valley and maximal second derivative showed higher overall TS than peak and maximal first derivative. Finger had higher overall TS and lower intra-subject TS variability than other measurement sites. Significance. Measurement site and type of pulse feature can significantly influence the timing of feature points on filtered PPG signals. Filtering parameters should be quoted to support the reproducibility of PPG-related studies.

multi-site photoplethysmography (PPG) pulse wave feature point filtering time shift

SCI ; EI

英语

通讯

Southern University of Science and Technology[G02236002]

Biophysics ; Engineering ; Physiology

Biophysics ; Engineering, Biomedical ; Physiology

WOS:000679080900001

IOP PUBLISHING LTD

20215211392260

High pass filters ; Impulse response ; Morphology ; Photoplethysmography ; Standardization

Medicine and Pharmacology:461.6 ; Electric Filters:703.2 ; Codes and Standards:902.2 ; Physical Properties of Gases, Liquids and Solids:931.2 ; Materials Science:951

BIOLOGY & BIOCHEMISTRY

Web of Science

1.Coventry Univ, Res Ctr Intelligent Healthcare, Coventry CV1 5FB, W Midlands, England
2.Southern Univ Sci & Technol, Dept Elect & Elect Engn, Shenzhen 518055, Peoples R China

Liu, Haipeng,Allen, John,Khalid, Syed Ghufran,et al. Filtering-induced time shifts in photoplethysmography pulse features measured at different body sites: the importance of filter definition and standardization[J]. PHYSIOLOGICAL MEASUREMENT,2021,42(7).

Liu, Haipeng,Allen, John,Khalid, Syed Ghufran,Chen, Fei,&Zheng, Dingchang.(2021).Filtering-induced time shifts in photoplethysmography pulse features measured at different body sites: the importance of filter definition and standardization.PHYSIOLOGICAL MEASUREMENT,42(7).

Liu, Haipeng,et al."Filtering-induced time shifts in photoplethysmography pulse features measured at different body sites: the importance of filter definition and standardization".PHYSIOLOGICAL MEASUREMENT 42.7(2021).