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Computer Methods and Programs in... May 2022Pulse Rate Variability (PRV) has been widely used as a surrogate of Heart Rate Variability (HRV). However, there are several technical aspects that may affect the...
Effects of using different algorithms and fiducial points for the detection of interbeat intervals, and different sampling rates on the assessment of pulse rate variability from photoplethysmography.
OBJECTIVE
Pulse Rate Variability (PRV) has been widely used as a surrogate of Heart Rate Variability (HRV). However, there are several technical aspects that may affect the extraction of PRV information from pulse wave signals such as the photoplethysmogram (PPG). The aim of this study was to evaluate the effects of changing the algorithm and fiducial points used for determining inter-beat intervals (IBIs), as well as the PPG sampling rate, from simulated PPG signals with known PRV content.
METHODS
PPG signals were simulated using a proposed model, in which PRV information can be modelled. Two independent experiments were performed. First, 5 IBIs detection algorithms and 8 fiducial points were used for assessing PRV information from the simulated PPG signals, and time-domain and Poincaré plot indices were extracted and compared to the expected values according to the simulated PRV. The best combination of algorithms and fiducial points were determined for each index, using factorial designs. Then, using one of the best combinations, PPG signals were simulated with varying sampling rates. PRV indices were extracted and compared to the expected values using Student t-tests or Mann-Whitney U-tests.
RESULTS
From the first experiment, it was observed that AVNN and SD2 indices behaved similarly, and there was no significant influence of the fiducial points used. For other indices, there were several combinations that behaved similarly well, mostly based on the detection of the valleys of the PPG signal. There were differences according to the quality of the PPG signal. From the second experiment, it was observed that, for all indices but SDNN, the higher the sampling rate the better. AVNN and SD2 showed no statistical differences even at the lowest evaluated sampling rate (32 Hz), while RMSSD, pNN50, S, SD1 and SD1/SD2 showed good performance at sampling rates as low as 128 Hz.
CONCLUSION
The best combination of IBIs detection algorithms and fiducial points differs according to the application, but those based on the detection of the valleys of the PPG signal tend to show a better performance. The sampling rate of PPG signals for PRV analysis could be lowered to around 128 Hz, although it could be further lowered according to the application.
SIGNIFICANCE
The standardisation of PRV analysis could increase the reliability of this signal and allow for the comparison of results obtained from different studies. The obtained results allow for a first approach to establish guidelines for two important aspects in PRV analysis from PPG signals, i.e. the way the IBIs are segmented from PPG signals, and the sampling rate that should be used for these analyses. Moreover, a model for simulating PPG signals with PRV information has been proposed, which allows for the establishing of these guidelines while controlling for other variables, such as the quality of the PPG signal.
Topics: Algorithms; Electrocardiography; Heart Rate; Humans; Photoplethysmography; Reproducibility of Results; Signal Processing, Computer-Assisted; Syndactyly
PubMed: 35255373
DOI: 10.1016/j.cmpb.2022.106724 -
Sensors (Basel, Switzerland) Aug 2021Alterations of heart rate variability (HRV) are associated with various (patho)physiological conditions; therefore, HRV analysis has the potential to become a useful...
Alterations of heart rate variability (HRV) are associated with various (patho)physiological conditions; therefore, HRV analysis has the potential to become a useful diagnostic module of wearable/telemedical devices to support remote cardiovascular/autonomic monitoring. Continuous pulse recordings obtained by photoplethysmography (PPG) can yield pulse rate variability (PRV) indices similar to HRV parameters; however, it is debated whether PRV/HRV parameters are interchangeable. In this study, we assessed the PRV analysis module of a digital arterial PPG-based telemedical system (SCN4ALL). We used Bland-Altman analysis to validate the SCN4ALL PRV algorithm to Kubios Premium software and to determine the agreements between PRV/HRV results calculated from 2-min long PPG and ECG captures recorded simultaneously in healthy individuals (n = 33) at rest and during the cold pressor test, and in diabetic patients (n = 12) at rest. We found an ideal agreement between SCN4ALL and Kubios outputs (bias < 2%). PRV and HRV parameters showed good agreements for interbeat intervals, SDNN, and RMSSD time-domain variables, for total spectral and low-frequency power (LF) frequency-domain variables, and for non-linear parameters in healthy subjects at rest and during cold pressor challenge. In diabetics, good agreements were observed for SDNN, LF, and SD2; and moderate agreement was observed for total power. In conclusion, the SCN4ALL PRV analysis module is a good alternative for HRV analysis for numerous conventional HRV parameters.
Topics: Autonomic Nervous System; Electrocardiography; Heart Rate; Humans; Photoplethysmography; Telemedicine
PubMed: 34450986
DOI: 10.3390/s21165544 -
Journal of Applied Physiology... Mar 2020Low cardiorespiratory fitness (CRF) increases risk of all-cause mortality and cardiovascular events. Periodic CRF assessment can have an important preventive function....
Low cardiorespiratory fitness (CRF) increases risk of all-cause mortality and cardiovascular events. Periodic CRF assessment can have an important preventive function. The objective of this study was to develop a protocol-free method to estimate CRF in daily life based on heart rate (HR) and body acceleration measurements. Acceleration and HR data were collected from 37 subjects (men = 49%) while they performed a standardized laboratory activity protocol (sitting, walking, running, cycling) and during a 5-day free-living monitoring period. CRF was determined by oxygen uptake (V̇o) during maximal exercise testing. A doubly labeled water-validated equation was used to predict total energy expenditure (TEE) from acceleration data. A fitness index was defined as the ratio between TEE and HR (TEE-pulse). Activity recognition techniques were used to process acceleration features and classify sedentary, ambulatory, and other activity types. Regression equations based on TEE-pulse data from each activity type were developed to predict V̇o. TEE-pulse measured within each activity type of the laboratory protocol was highly correlated with V̇o ( from 0.74-0.91). Averaging the outcome of each activity-type specific equation based on TEE-pulse from the laboratory data led to accurate estimates of V̇o [root mean square error (RMSE): 300 mL O/min, or 10%]. The difference between laboratory and free-living determined TEE-pulse was 3.7 ± 11% ( = 0.85). The prediction method preserved the prediction accuracy when applied to free-living data (RMSE: 367 mL O/min, or 12%). Measurements of body acceleration and HR can be used to predict V̇o in daily life. Activity-specific prediction equations are needed to achieve highly accurate estimates of CRF. This is among the very few studies validating, in free-living conditions, a method to estimate cardiorespiratory fitness using heart rate and body acceleration data. A novel parameter called TEE-pulse, which was defined as the ratio between accelerometer-determined energy expenditure and heart rate, was highly correlated with maximal oxygen uptake (V̇o). Activity classification and the use of activity-selective prediction equations outperformed previously published methods for estimating V̇o from heart rate and acceleration data.
Topics: Cardiorespiratory Fitness; Energy Metabolism; Exercise Test; Heart Rate; Humans; Male; Oxygen Consumption; Walking
PubMed: 31999530
DOI: 10.1152/japplphysiol.00631.2019 -
PloS One 2022We study the relationships between the real-time psychophysiological activity of professional traders, their financial transactions, and market fluctuations. We...
We study the relationships between the real-time psychophysiological activity of professional traders, their financial transactions, and market fluctuations. We collected multiple physiological signals such as heart rate, blood volume pulse, and electrodermal activity of 55 traders at a leading global financial institution during their normal working hours over a five-day period. Using their physiological measurements, we implemented a novel metric of trader's "psychophysiological activation" to capture affect such as excitement, stress and irritation. We find statistically significant relations between traders' psychophysiological activation levels and such as their financial transactions, market fluctuations, the type of financial products they traded, and their trading experience. We conducted post-measurement interviews with traders who participated in this study to obtain additional insights in the key factors driving their psychophysiological activation during financial risk processing. Our work illustrates that psychophysiological activation plays a prominent role in financial risk processing for professional traders.
Topics: Commerce; Heart Rate; Psychophysiology
PubMed: 35877608
DOI: 10.1371/journal.pone.0269752 -
Journal of the Association For Research... Jun 2023The auditory brainstem implant (ABI) is an auditory neuroprosthesis that provides hearing by electrically stimulating the cochlear nucleus (CN) of the brainstem. Our...
The auditory brainstem implant (ABI) is an auditory neuroprosthesis that provides hearing by electrically stimulating the cochlear nucleus (CN) of the brainstem. Our previous study (McInturff et al., 2022) showed that single-pulse stimulation of the dorsal (D)CN subdivision with low levels of current evokes responses that have early latencies, different than the late response patterns observed from stimulation of the ventral (V)CN. How these differing responses encode more complex stimuli, such as pulse trains and amplitude modulated (AM) pulses, has not been explored. Here, we compare responses to pulse train stimulation of the DCN and VCN, and show that VCN responses, measured in the inferior colliculus (IC), have less adaption, higher synchrony, and higher cross-correlation. However, with high-level DCN stimulation, responses become like those to VCN stimulation, supporting our earlier hypothesis that current spreads from electrodes on the DCN to excite neurons located in the VCN. To AM pulses, stimulation of the VCN elicits responses with larger vector strengths and gain values especially in the high-CF portion of the IC. Additional analysis using neural measures of modulation thresholds indicate that these measures are lowest for VCN. Human ABI users with low modulation thresholds, who score best on comprehension tests, may thus have electrode arrays that stimulate the VCN. Overall, the results show that the VCN has superior response characteristics and suggest that it should be the preferred target for ABI electrode arrays in humans.
Topics: Animals; Humans; Auditory Brain Stem Implants; Heart Rate; Cochlear Nucleus; Hearing; Models, Animal; Electric Stimulation
PubMed: 37156973
DOI: 10.1007/s10162-023-00897-z -
PloS One 2021The importance of workers' well-being has been recognized in recent years. The assessment of well-being has been subjective, and few studies have sought potential...
The importance of workers' well-being has been recognized in recent years. The assessment of well-being has been subjective, and few studies have sought potential biomarkers of well-being to date. This study examined the relationship between well-being and the LF/HF ratio, an index of heart rate variability that reflects sympathetic and parasympathetic nerve activity. Pulse waves were measured using photoplethysmography through a web camera attached to the computer used by each participant. The participants were asked to measure their pulse waves while working for 4 weeks, and well-being was assessed using self-reported measures such as the Satisfaction With Life Scale (SWLS), the Positive and Negative Affect Schedule (PANAS), and the Flourishing Scale (FS). Each of the well-being scores were split into two groups according to the median value, and the LF/HF ratio during work, as well as the number of times an LF/HF ratio threshold was either exceeded or subceeded, were compared between the high and low SWLS, positive emotion, negative emotion, and FS groups. Furthermore, to examine the effects of the LF/HF ratio and demographic characteristics on well-being, a multiple regression analysis was conducted. Data were obtained from 169 participants. The results showed that the low FS group had a higher mean LF/HF ratio during work than the high FS group. No significant differences were seen between the high and low SWLS groups, the high and low positive emotion groups, or the high and low negative emotion groups. The multiple regression analysis showed that the mean LF/HF ratio during work affected the FS and SWLS scores, and the number of times the mean LF/HF ratio exceeded +3 SD had an effect on the positive emotion. No effect of the LF/HF ratio on negative emotions was shown. The LF/HF ratio might be applicable as an objective measure of well-being.
Topics: Adult; Emotions; Female; Heart Rate; Humans; Male; Personal Satisfaction; Sedentary Behavior; Work
PubMed: 34492071
DOI: 10.1371/journal.pone.0257062 -
JACC. Clinical Electrophysiology Jul 2022
Topics: Atrial Fibrillation; Ganglia, Autonomic; Heart Rate; Humans
PubMed: 35863817
DOI: 10.1016/j.jacep.2022.05.006 -
Sensors (Basel, Switzerland) Oct 2020The aim was to examine the validity of heart rate variability (HRV) measurements from photoplethysmography (PPG) via a smartphone application pre- and post-resistance...
The aim was to examine the validity of heart rate variability (HRV) measurements from photoplethysmography (PPG) via a smartphone application pre- and post-resistance exercise (RE) and to examine the intraday and interday reliability of the smartphone PPG method. Thirty-one adults underwent two simultaneous ultrashort-term electrocardiograph (ECG) and PPG measurements followed by 1-repetition maximum testing for back squats, bench presses, and bent-over rows. The participants then performed RE, where simultaneous ultrashort-term ECG and PPG measurements were taken: two pre- and one post-exercise. The natural logarithm of the root mean square of successive normal-to-normal (R-R) differences (LnRMSSD) values were compared with paired-sample -tests, Pearson product correlations, Cohen's effect sizes (ESs), and Bland-Altman analysis. Intra-class correlations (ICC) were determined between PPG LnRMSSDs. Significant, small-moderate differences were found for all measurements between ECG and PPG: Base (ES = 0.42), Base (0.30), RE (0.26), RE (0.36), and RE (1.14). The correlations ranged from moderate to very large: Base ( = 0.59), Base ( = 0.63), RE ( = 0.63), RE ( = 0.76), and RE ( = 0.41)-all < 0.05. The agreement for all the measurements was "moderate" (0.10-0.16). The PPG LnRMSSD exhibited "nearly-perfect" intraday reliability (ICC = 0.91) and "very large" interday reliability (0.88). The smartphone PPG was comparable to the ECG for measuring HRV at rest, but with larger error after resistance exercise.
Topics: Adult; Electrocardiography; Heart Rate; Humans; Photoplethysmography; Reproducibility of Results; Resistance Training; Smartphone
PubMed: 33050249
DOI: 10.3390/s20205738 -
GeroScience Aug 2023This study aims to examine the association between baseline level and change of autonomic nervous function with subsequent development of arterial stiffness. Autonomic...
This study aims to examine the association between baseline level and change of autonomic nervous function with subsequent development of arterial stiffness. Autonomic nervous function was assessed in 4901 participants of the Whitehall II occupational cohort by heart rate variability (HRV) indices and resting heart rate (rHR) three times between 1997 and 2009, while arterial stiffness was assessed by carotid-femoral pulse wave velocity (PWV) measured twice between 2007 and 2013. First, individual HRV/rHR levels and annual changes were estimated. Then, we modelled the development of PWV by HRV/rHR using linear mixed effect models. First, we adjusted for sex and ethnicity (model 1), and then for socioeconomic and lifestyle factors, various clinical measurements, and medications (model 2). A decrease in HRV and unchanged rHR was associated with subsequent higher levels of PWV, but the effect of a change in HRV was less pronounced at higher ages. A typical individual aged 65 years with a SDNN level of 30 ms and a 2% annual decrease in SDNN had 1.32 (0.95; 1.69) higher PWV compared to one with the same age and SDNN level but with a 1% annual decrease in SDNN. Further adjustment had no major effect on the results. People who experience a steeper decline in autonomic nervous function have higher levels of arterial stiffness. The association was stronger in younger people.
Topics: Humans; Vascular Stiffness; Pulse Wave Analysis; Heart Rate
PubMed: 37074615
DOI: 10.1007/s11357-023-00762-0 -
Open Heart Nov 2023Peak oxygen pulse (Opulse=oxygen consumption/heart rate) is calculated by the product of stroke volume (SV) and oxygen extraction. It has been shown to be reduced in...
BACKGROUND
Peak oxygen pulse (Opulse=oxygen consumption/heart rate) is calculated by the product of stroke volume (SV) and oxygen extraction. It has been shown to be reduced in patients with a Fontan circulation. However, in the Fontan population, it may be a poor marker of SV. We propose that the slope of the O pulse curve may be more reflective of SV during exercise.
METHODS
We analysed cardiopulmonary exercise test data in 22 subjects with a Fontan circulation (cohort A) and examined the association between peak SV during exercise (aortic flow measured on exercise cardiac MRI), and O pulse parameters (absolute O pulse and O pulse slopes up to anaerobic threshold (AT) and peak exercise). In a separate Fontan cohort (cohort B, n=131), associations between clinical characteristics and O pulse kinetics were examined.
RESULTS
In cohort A, peak aortic flow was moderately and significantly associated with Opulseslope (r=0.47, p=0.02). However, neither absolute Opulse nor Opulse was significantly associated with peak aortic flow. In cohort B, Opulseslope and Opulseslope were not significantly associated with clinical parameters, apart from a weak association with forced vital capacity.
CONCLUSION
The slope of the O pulse curve to peak exercise may be more reflective of peak SV in the Fontan population than a single peak O pulse value.
Topics: Humans; Fontan Procedure; Stroke Volume; Heart Rate; Exercise Test; Oxygen
PubMed: 37935560
DOI: 10.1136/openhrt-2023-002324