Abstract
Objective: Objective assessment of autonomic function is important, including the investigation of slow-paced breathing to induce associated periodic changes in the cardiovascular system – such as blood pressure and heart rate. However, pulse changes across a range of peripheral body sites have seldom been explored with this challenge. The primary aim of this pilot study was to utilize multi-site photoplethysmography (MPPG) technology to quantify the phase delays, i.e., correlation lags, between changes in heart rate and changes in key pulse features with slow-paced breathing (0.1 Hz).Methods: Waveforms were collected simultaneously from the right and left ear lobes, thumbs, and great toes of 18 healthy adult subjects. Cross correlation lags between reference beat-to-beat changes in electrocardiogram (ECG) R-R wave interval and changes in pulse arrival time (foot of pulse; PATf) and also for pulse amplitude (foot-to-peak; AMP) were determined.Results: Relative to R-R changes, the median ear, thumb, and toe PATf correlation lags were 3.4, 2.9, and 2.1 beats, respectively; contrasting to AMP with 5.7, 6.0, and 6.9 beats, respectively. These PATf correlation lags in beats were significantly lower than for the AMP measure. Segmental differences between sites and timing measure variability have also been quantified.Conclusion: This pilot study has indicated bilateral similarity plus segmental differences for relative delays in PPG pulse timing and amplitude measures relative to R-R interval changes with paced breathing. These correlation and variability data are now available for comparison with cardiovascular patient groups to support development of autonomic function assessment techniques.
Highlights
A pulse is transmitted to the periphery with each heartbeat, with propagation characteristics influenced by aging and/or cardiovascular disease
Overall ranges for correlation lags and PPG variability (e.g., SD-PATf) normalized to R-R interval variability (SD-RR) are summarized in Figures 2A–C, using the mean of right and left body sides
Cross correlation and variability data have been obtained for multi-site photoplethysmography (MPPG) head-to-foot pulse measurements plus ECG during a slow, i.e., 0.1 Hz paced breathing exercise
Summary
A pulse is transmitted to the periphery with each heartbeat, with propagation characteristics influenced by aging and/or cardiovascular disease. MPPG has shown value in the study of changes in pulse with aging (Allen and Murray, 2002), peripheral arterial disease (Allen et al, 2008; Bentham et al, 2018), connective tissue disease (McKay et al, 2014), endothelial function (Selvaraj et al, 2009), and arterial stiffness (Sharkey et al, 2018). PPG characteristics can be modulated in this way (Allen and Murray, 2000b,c) but noting that only limited data have been published so far, i.e., relationship between finger pulse transit time and cardiac electrocardiogram (ECG) R-R interval changes (Drinnan et al, 2001). As far as the author is aware, there have been no comparative published studies quantifying the phase relationships between simultaneous head-to-foot PPG pulse timing and amplitude changes and R-R interval changes, such data could yield valuable information for cardiovascular system assessment. The primary aim of this pilot study was to quantify the correlation lags between MPPG pulse timing/amplitude changes and R-R interval changes under a standardized slow-paced breathing challenge
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
