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Journal of Physiological Anthropology Aug 2020With the popularization of pulse wave signals by the spread of wearable watch devices incorporating photoplethysmography (PPG) sensors, many studies are reporting the...
With the popularization of pulse wave signals by the spread of wearable watch devices incorporating photoplethysmography (PPG) sensors, many studies are reporting the accuracy of pulse rate variability (PRV) as a surrogate of heart rate variability (HRV). However, the authors are concerned about their research paradigm based on the assumption that PRV is a biomarker that reflects the same biological properties as HRV. Because PPG pulse wave and ECG R wave both reflect the periodic beating of the heart, pulse rate and heart rate should be equal, but it does not guarantee that the respective variabilities are also the same. The process from ECG R wave to PPG pulse wave involves several transformation steps of physical properties, such as those of electromechanical coupling and conversions from force to volume, volume to pressure, pressure impulse to wave, pressure wave to volume, and volume to light intensity. In fact, there is concreate evidence that shows discrepancy between PRV and HRV, such as that demonstrating the presence of PRV in the absence of HRV, differences in PRV with measurement sites, and differing effects of body posture and exercise between them. Our observations in adult patients with an implanted cardiac pacemaker also indicate that fluctuations in R-R intervals, pulse transit time, and pulse intervals are modulated differently by autonomic functions, respiration, and other factors. The authors suggest that it is more appropriate to recognize PRV as a different biomarker than HRV. Although HRV is a major determinant of PRV, PRV is caused by many other sources of variability, which could contain useful biomedical information that is neither error nor noise.
Topics: Aged, 80 and over; Biomarkers; Female; Heart Rate; Humans; Photoplethysmography; Posture; Signal Processing, Computer-Assisted
PubMed: 32811571
DOI: 10.1186/s40101-020-00233-x -
Journal of the Association For Research... Oct 2015To further understand the response of the human brainstem to electrical stimulation, a series of experiments compared the effect of pulse rate and polarity on detection...
To further understand the response of the human brainstem to electrical stimulation, a series of experiments compared the effect of pulse rate and polarity on detection thresholds between auditory brainstem implant (ABI) and cochlear implant (CI) patients. Experiment 1 showed that for 400-ms pulse trains, ABI users' thresholds dropped by about 2 dB as pulse rate was increased from 71 to 500 pps, but only by an average of 0.6 dB as rate was increased further to 3500 pps. This latter decrease was much smaller than the 7.7-dB observed for CI users. A similar result was obtained for pulse trains with a 40-ms duration. Furthermore, experiment 2 showed that the threshold difference between 500- and 3500-pps pulse trains remained much smaller for ABI than for CI users, even for durations as short as 2 ms, indicating the effect of a fast-acting mechanism. Experiment 3 showed that ABI users' thresholds were lower for alternating-polarity than for fixed-polarity pulse trains, and that this difference was greater at 3500 pps than at 500 pps, consistent with the effect of pulse rate on ABI users' thresholds being influenced by charge interactions between successive biphasic pulses. Experiment 4 compared thresholds and loudness between trains of asymmetric pulses of opposite polarity, in monopolar mode, and showed that in both cases less current was needed when the anodic, rather than the cathodic, current was concentrated into a short time interval. This finding is similar to that previously observed for CI users and is consistent with ABI users being more sensitive to anodic than cathodic current. We argue that our results constrain potential explanations for the differences in the perception of electrical stimulation by CI and ABI users, and have potential implications for future ABI stimulation strategies.
Topics: Adult; Aged; Aged, 80 and over; Auditory Brain Stem Implants; Auditory Threshold; Cochlear Implants; Electric Stimulation; Heart Rate; Humans; Loudness Perception; Middle Aged
PubMed: 26138501
DOI: 10.1007/s10162-015-0530-z -
Sensors (Basel, Switzerland) Apr 2023Photoplethysmography (PPG) signals have been widely used in evaluating cardiovascular biomarkers, however, there is a lack of in-depth understanding of the remote usage...
Real-Time Evaluation of Time-Domain Pulse Rate Variability Parameters in Different Postures and Breathing Patterns Using Wireless Photoplethysmography Sensor: Towards Remote Healthcare in Low-Resource Communities.
Photoplethysmography (PPG) signals have been widely used in evaluating cardiovascular biomarkers, however, there is a lack of in-depth understanding of the remote usage of this technology and its viability for underdeveloped countries. This study aims to quantitatively evaluate the performance of a low-cost wireless PPG device in detecting ultra-short-term time-domain pulse rate variability (PRV) parameters in different postures and breathing patterns. A total of 30 healthy subjects were recruited. ECG and PPG signals were simultaneously recorded in 3 min using miniaturized wearable sensors. Four heart rate variability (HRV) and PRV parameters were extracted from ECG and PPG signals, respectively, and compared using analysis of variance (ANOVA) or Scheirer-Ray-Hare test with post hoc analysis. In addition, the data loss was calculated as the percentage of missing sampling points. Posture did not present statistical differences across the PRV parameters but a statistical difference between indicators was found. Strong variation was found for the RMSSD indicator in the standing posture. The sitting position in both breathing patterns demonstrated the lowest data loss (1.0 ± 0.6 and 1.0 ± 0.7) and the lowest percentage of different factors for all indicators. The usage of commercial PPG and BLE devices can allow the reliable extraction of the PPG signal and PRV indicators in real time.
Topics: Humans; Heart Rate; Photoplethysmography; Posture; Healthy Volunteers; Respiration; Electrocardiography
PubMed: 37177450
DOI: 10.3390/s23094246 -
Journal of Clinical Hypertension... Jun 2021Systolic blood pressure (SBP) and resting pulse rate (RPR) have been linked to mortality and cardiovascular events in younger population. Till now, no studies...
Systolic blood pressure (SBP) and resting pulse rate (RPR) have been linked to mortality and cardiovascular events in younger population. Till now, no studies simultaneously investigate the non-linear association of SBP and RPR with all-cause and cardiovascular mortality among population aged 80 and older. Data of 2828 eligible participants were selected from electronic health records linked attended automated office blood pressure measurement system. The dose-response relationship between the SBP, RPR, and the risk of all-cause and cardiovascular mortality was analyzed by Cox model with restricted cubic splines. During the 3.6-year follow-up, 442 deaths occurred. Comparing with the optimal SBP (117-145 mmHg), the lower (HR: 1.39, 95% CI: 1.07-1.81) and higher SBP (HR: 1.34, 95% CI: 1.08-1.65) were significantly associated with an increasing risk of all-cause mortality. The higher SBP (>144 mmHg) was associated with cardiovascular mortality, with the HR (95% CI) as 1.51 (1.07-2.12). The faster RPR showed the higher risk of all-cause (HR: 1.36, 95% CI: 1.05-1.76) and cardiovascular (HR: 1.51, 95% CI: 1.07-2.13) mortality. We found both higher SBP and faster RPR were independently associated with all-cause and cardiovascular mortality, and lower SBP was only associated with the increased risk of all-cause mortality in oldest old community-dwelling Chinese population. Our results demonstrate the prognostic importance of both SBP and RPR in the elderly.
Topics: Aged; Aged, 80 and over; Blood Pressure; Blood Pressure Determination; Cardiovascular Diseases; Heart Rate; Humans; Hypertension; Independent Living; Risk Factors
PubMed: 33949090
DOI: 10.1111/jch.14251 -
Noninvasive Non-Contact SpO Monitoring Using an Integrated Polarization-Sensing CMOS Imaging Sensor.Sensors (Basel, Switzerland) Oct 2022In the diagnosis and primary health care of an individual, estimation of the pulse rate and blood oxygen saturation (SpO2) is critical. The pulse rate and SpO2 are...
BACKGROUND
In the diagnosis and primary health care of an individual, estimation of the pulse rate and blood oxygen saturation (SpO2) is critical. The pulse rate and SpO2 are determined by methods including photoplethysmography (iPPG), light spectroscopy, and pulse oximetry. These devices need to be compact, non-contact, and noninvasive for real-time health monitoring. Reflection-based iPPG is becoming popular as it allows non-contact estimation of the heart rate and SpO2. Most iPPG methods capture temporal data and form complex computations, and thus real-time measurements and spatial visualization are difficult.
METHOD
In this research work, reflective mode polarized imaging-based iPPG is proposed. For polarization imaging, a custom image sensor with wire grid polarizers on each pixel is designed. Each pixel has a wire grid of varying transmission axes, allowing phase detection of the incoming light. The phase information of the backscattered light from the fingertips of 12 healthy volunteers was recorded in both the resting as well as the excited states. These data were then processed using MATLAB 2021b software.
RESULTS
The phase information provides quantitative information on the reflection from the superficial and deep layers of skin. The ratio of deep to superficial layer backscattered phase information is shown to be directly correlated and linearly increasing with an increase in the SpO2 and heart rate.
CONCLUSIONS
The phase-based measurements help to monitor the changes in the resting and excited state heart rate and SpO2 in real time. Furthermore, the use of the ratio of phase information helps to make the measurements independent of the individual skin traits and thus increases the accuracy of the measurements. The proposed iPPG works in ambient light, relaxing the instrumentation requirement and helping the system to be compact and portable.
Topics: Humans; Oximetry; Photoplethysmography; Monitoring, Physiologic; Heart Rate; Fingers; Oxygen
PubMed: 36298147
DOI: 10.3390/s22207796 -
F1000Research 2023Research on the compatibility of time domain indices, frequency domain measurements of heart rate variability obtained from electrocardiogram (ECG) waveforms, and... (Observational Study)
Observational Study
Analysis of time-domain indices, frequency domain measures of heart rate variability derived from ECG waveform and pulse-wave-related HRV among overweight individuals: an observational study.
Research on the compatibility of time domain indices, frequency domain measurements of heart rate variability obtained from electrocardiogram (ECG) waveforms, and pulse wave signal (pulse rate variability; PRV) features is ongoing. The promising marker of cardiac autonomic function is heart rate variability. Recent research has looked at various other physiological markers, leading to the emergence of pulse rate variability. The pulse wave signal can be studied for variations to understand better changes in arterial stiffness and compliance, which are key indicators of cardiovascular health. 35 healthy overweight people were included. The Lead II electrocardiogram (ECG) signal was transmitted through an analog-to-digital converter (PowerLab 8/35 software, AD Instruments Pty. Ltd., New South Wales, Australia). This signal was utilized to compute Heart Rate Variability (HRV) and was sampled at a rate of 1024 Hz. The same AD equipment was also used to capture a pulse signal simultaneously. The right index finger was used as the recording site for the pulse signal using photoplethysmography (PPG) technology. The participants' demographic data show that the mean age was 23.14 + 5.27 years, the mean weight was 73.68 + 7.40 kg, the mean body fat percentage was 32.23 + 5.30, and the mean visceral fat percentage was 4.60 + 2.0. The findings revealed no noticeable difference between the median values of heart rate variability (HRV) and PRV. Additionally, a strong correlation was observed between HRV and PRV. However, poor agreement was observed in the measurement of PRV and HRV. All indices of HRV showed a greater correlation with PRV. However, the level of agreement between HRV and PRV measurement was poor. Hence, HRV cannot be replaced with PRV and vice-versa.
Topics: Humans; Adolescent; Young Adult; Adult; Heart Rate; Overweight; Heart; Electrocardiography; Photoplethysmography
PubMed: 37799491
DOI: 10.12688/f1000research.139283.1 -
Journal of Applied Physiology... Aug 2021Postprandial superior mesenteric artery (SMA) blood flow is associated with the caloric content of a meal. Whether spectral analysis of a peripheral pulse wave or heart... (Randomized Controlled Trial)
Randomized Controlled Trial
Postprandial superior mesenteric artery (SMA) blood flow is associated with the caloric content of a meal. Whether spectral analysis of a peripheral pulse wave or heart rate can model postprandial SMA blood flow is unclear. We hypothesized that altering the caloric content of a meal would evoke dose-response increases in postprandial SMA hyperemia and distinct changes in the pulse wave harmonic spectrum and heart rate. Twenty healthy subjects (10 male, 26 ± 10 yr) completed a randomized cross-over trial, comparing three meals (280, 560, or 840 kcal) on SMA blood flow (Doppler ultrasound), heart rate, and the first to seventh harmonic amplitudes (derived from a finger pulse wave). Supine SMA diameter and blood velocity were collected at baseline and every 15 min throughout 2 h of postprandial recovery. SMA blood flow was smaller across all time points following (280 kcal) compared with both (560 kcal) and (840 kcal) (all < 0.001), while had attenuated responses compared with at 60, 90, 105, and 120 min postprandial (all < 0.01). Distinct changes in heart rate and the amplitude of second to fifth harmonics were observed between meals (all < 0.05). The changes in harmonic spectrum or heart rate explained 66-69% (adjusted ) of the variance in postprandial SMA blood flow. These results provide proof-of-concept that easily obtained and noninvasive postprandial harmonic profiles or heart rate may be used to explain changes in SMA blood flow and exploited for the development of wearable technology to noninvasively track caloric intake. We studied the superior mesenteric artery (SMA) blood flow responses to three meals of varying caloric value and examined whether these responses could be modeled using changes in heart rate or the peripheral pulse wave harmonic spectrum. We found that both inputs could explain 66-69% of the SMA blood flow variance over 2 h of postprandial recovery. Noninvasive methods may be able to predict SMA blood flow and thus used to measure caloric intake.
Topics: Heart Rate; Hemodynamics; Humans; Male; Mesenteric Artery, Superior; Postprandial Period; Wearable Electronic Devices
PubMed: 34264128
DOI: 10.1152/japplphysiol.00903.2020 -
Journal of Veterinary Internal Medicine Mar 2021Measured indirect blood pressure (BP) results in cats in a clinical environment might be affected by stress and characteristics of the cats.
Influence of clinical setting and cat characteristics on indirectly measured blood pressure and pulse rate in healthy Birman, Norwegian Forest, and Domestic Shorthair cats.
BACKGROUND
Measured indirect blood pressure (BP) results in cats in a clinical environment might be affected by stress and characteristics of the cats.
HYPOTHESIS
To investigate the influence of clinical setting, cat characteristics, and life situation on BP and pulse rate (PR) in healthy cats.
ANIMALS
Ninety-four healthy Domestic Shorthair, Birman and Norwegian Forest cats.
METHODS
Blood pressure measured by high-definition oscillometry in 3 settings: cat placed in its own carrier with veterinarian present; cat placed in carrier with owner alone present; and cat placed on table with veterinarian present. Statistical analyses were performed using mixed linear models.
RESULTS
Systolic BP (SBP) did not differ among settings. Higher mean arterial pressure (MAP), diastolic BP (DBP), and PR were found when measurements were performed with cat placed on table, rather than in carrier. Coefficients of variation (CVs) higher for SBP, MAP, DBP, and PR when measured with cat placed on table than in carrier. Birman cats had lower BP than other breeds. Systolic BP, MAP, DBP, and PR increased with age. Cats allowed outdoors had lower PR than cats living strictly indoors.
CONCLUSION AND CLINICAL IMPORTANCE
No difference in SBP was found among settings, but measuring BP with the cat placed on the examination table gave higher MAP, DBP, PR, and CV than measuring BP with the cat in its carrier. Breed affected BP, with lower BP in Birman cats than other breeds. Blood pressure increased with age. Pulse rate was lower in cats allowed outdoors than cats living strictly indoors.
Topics: Animals; Blood Pressure; Cats; Forests; Heart Rate; Oscillometry
PubMed: 33675246
DOI: 10.1111/jvim.16096 -
Physiological Reports Jul 2022The present study aims to analyze the systemic response to auditory stimulation by means of hemodynamic (cephalic and peripheral) and autonomic responses in a broad...
The present study aims to analyze the systemic response to auditory stimulation by means of hemodynamic (cephalic and peripheral) and autonomic responses in a broad range of auditory intensities (70.9, 77.9, 84.5, 89.5, 94.5 dBA). This approach could help to understand the possible influence of the autonomic nervous system on the cephalic blood flow. Twenty-five subjects were exposed to auditory stimulation while electrodermal activity (EDA), photoplethysmography (PPG), electrocardiogram, and functional near-infrared spectroscopy signals were recorded. Seven trials with 20 individual tones, each for the five intensities, were presented. The results showed a differentiated response to the higher intensity (94.5 dBA) with a decrease in some peripheral signals such as the heart rate (HR), the pulse signal, the pulse transit time (PTT), an increase of the LFnu power in PPG, and at the head level a decrease in oxygenated and total hemoglobin concentration. After the regression of the visual channel activity from the auditory channels, a decrease in deoxyhemoglobin in the auditory cortex was obtained, indicating a likely active response at the highest intensity. Nevertheless, other measures, such as EDA (Phasic and Tonic), and heart rate variability (Frequency and time domain) showed no significant differences between intensities. Altogether, these results suggest a systemic and complex response to high-intensity auditory stimuli. The results obtained in the decrease of the PTT and the increase in LFnu power of PPG suggest a possible vasoconstriction reflex by a sympathetic control of vascular tone, which could be related to the decrease in blood oxygenation at the head level.
Topics: Acoustic Stimulation; Auditory Cortex; Heart Rate; Hemodynamics; Humans; Photoplethysmography
PubMed: 35785451
DOI: 10.14814/phy2.15372 -
American Journal of Veterinary Research Apr 2021To evaluate the repeatability and accuracy of fingertip pulse oximeters (FPO) for measurement of hemoglobin oxygen saturation in arterial blood and pulse rate (PR) in...
Repeatability and accuracy of fingertip pulse oximeters for measurement of hemoglobin oxygen saturation in arterial blood and pulse rate in anesthetized dogs breathing 100% oxygen.
OBJECTIVE
To evaluate the repeatability and accuracy of fingertip pulse oximeters (FPO) for measurement of hemoglobin oxygen saturation in arterial blood and pulse rate (PR) in anesthetized dogs breathing 100% O.
ANIMALS
29 healthy client-owned anesthetized dogs undergoing various surgical procedures.
PROCEDURES
In randomized order, each of 7 FPOs or a reference pulse oximeter (PO) was applied to the tongue of each intubated anesthetized dog breathing 100% O. Duplicate measurements of oxygen saturation (Spo) and PR were obtained within 60 seconds of applying an FPO or PO. A nonparametric version of Bland-Altman analysis was used. Coefficient of repeatability was the interval between the 5th and 95th percentiles of the differences between duplicate measurements. Bias was the median difference, and the limits of agreement were the 5th and 95th percentiles of the differences between each FPO and the PO. Acceptable values for the coefficient of repeatability of Spo were ≤ 6%. Agreements were accepted if the limits of agreement had an absolute difference of ≤ ± 3% in Spo and relative difference of ≤ ± 10% in PR.
RESULTS
Coefficient of repeatability for Spo was acceptable for 5 FPOs, but the limits of agreement for Spo were unacceptable for all FPOs. The limits of agreement for PR were acceptable for 2 FPOs.
CONCLUSIONS AND CLINICAL RELEVANCE
Results suggested that some FPOs may be suitable for accurately monitoring PRs of healthy anesthetized dogs breathing 100% O, but mild underestimation of Spo was common.
Topics: Animals; Dogs; Heart Rate; Hemoglobins; Oximetry; Oxygen; Respiration
PubMed: 33764836
DOI: 10.2460/ajvr.82.4.268