Filtering-induced changes of pulse transmit time across different ages: a neglected concern in photoplethysmography-based cuffless blood pressure measurement

Liao，Shangdi1; Liu，Haipeng2; Lin，Wan Hua3; Zheng，Dingchang2; Chen，Fei1

2023

10.3389/fphys.2023.1172150

Frontiers in Physiology   Impact Factor & Quartile

1664-042X

Background: Pulse transit time (PTT) is a key parameter in cuffless blood pressure measurement based on photoplethysmography (PPG) signals. In wearable PPG sensors, raw PPG signals are filtered, which can change the timing of PPG waveform feature points, leading to inaccurate PTT estimation. There is a lack of comprehensive investigation of filtering-induced PTT changes in subjects with different ages. Objective: This study aimed to quantitatively investigate the effects of aging and PTT definition on the infinite impulse response (IIR) filtering-induced PTT changes. Methods: One hundred healthy subjects in five different ranges of age (i.e., 20–29, 30–39, 40–49, 50–59, and over 60 years old, 20 subjects in each) were recruited. Electrocardiogram (ECG) and PPG signals were recorded simultaneously for 120 s. PTT was calculated from the R wave of ECG and PPG waveform features. Eight PTT definitions were developed from different PPG waveform feature points. The raw PPG signals were preprocessed then further low-pass filtered. The difference between PTTs derived from preprocessed and filtered PPG signals, and the relative difference, were calculated and compared among five age groups and eight PTT definitions using the analysis of variance (ANOVA) or Scheirer–Ray–Hare test with post hoc analysis. Linear regression analysis was used to investigate the relationship between age and filtering-induced PTT changes. Results: Filtering-induced PTT difference and the relative difference were significantly influenced by age and PTT definition (p < 0.001 for both). Aging effect on filtering-induced PTT changes was consecutive with a monotonous trend under all PTT definitions. The age groups with maximum and minimum filtering-induced PTT changes depended on the definition. In all subjects, the PTT defined by maximum peak of PPG had the minimum filtering-induced PTT changes (mean: 16.16 ms and 5.65% for PTT difference and relative difference). The changes of PTT defined by maximum first PPG derivative had the strongest linear relationship with age (R-squared: 0.47 and 0.46 for PTT difference relative difference). Conclusion: The filtering-induced PTT changes are significantly influenced by age and PTT definition. These factors deserve further consideration to improve the accuracy of PPG-based cuffless blood pressure measurement using wearable sensors.

cuffless blood pressure measurement filtering photoplethysmography (PPG) pulse transit time (PTT) waveform feature

SCI

English

First ; Corresponding

Shenzhen Key Technology Program Funding[JSGG20220831103803006]

Physiology

Physiology

WOS:001044061500001

FRONTIERS MEDIA SA

2-s2.0-85167348979

Scopus

1.Department of Electronic and Electrical Engineering,Southern University of Science and Technology,Shenzhen,China
2.Research Centre for Intelligent Healthcare,Coventry University,Coventry,United Kingdom
3.Chinese Academy of Sciences Key Laboratory of Human-Machine Intelligence-Synergy Systems,Shenzhen Institute of Advanced Technology,Shenzhen,China

Liao，Shangdi,Liu，Haipeng,Lin，Wan Hua,et al. Filtering-induced changes of pulse transmit time across different ages: a neglected concern in photoplethysmography-based cuffless blood pressure measurement[J]. Frontiers in Physiology,2023,14.

Liao，Shangdi,Liu，Haipeng,Lin，Wan Hua,Zheng，Dingchang,&Chen，Fei.(2023).Filtering-induced changes of pulse transmit time across different ages: a neglected concern in photoplethysmography-based cuffless blood pressure measurement.Frontiers in Physiology,14.

Liao，Shangdi,et al."Filtering-induced changes of pulse transmit time across different ages: a neglected concern in photoplethysmography-based cuffless blood pressure measurement".Frontiers in Physiology 14(2023).