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Sensors (Basel, Switzerland) Jan 2023Mathematical and signal-processing methods were used to obtain reliable measurements of the heartbeat pulse rate and information on oxygen concentration in the blood...
Mathematical and signal-processing methods were used to obtain reliable measurements of the heartbeat pulse rate and information on oxygen concentration in the blood using short video recordings of the index finger attached to a smartphone built-in camera. Various types of smartphones were used with different operating systems (e.g., iOS, Android) and capabilities. A range of processing algorithms were applied to the red-green-blue (RGB) component signals, including mean intensity calculation, moving average smoothing, and quadratic filtering based on the Savitzky-Golay filter. Two approaches-gradient and local maximum methods-were used to determine the pulse rate, which provided similar results. A fast Fourier transform was applied to the signal to correlate the signal's frequency components with the pulse rate. We resolved the signal into its DC and AC components to calculate the ratio-of-ratios of the AC and DC components of the red and green signals, a method which is often used to estimate the oxygen concentration in blood. A series of measurements were performed on healthy human subjects, producing reliable data that compared favorably to benchmark data obtained by commercial and medically approved oximeters. Furthermore, the effect of the video recording duration on the accuracy of the results was investigated.
Topics: Humans; Smartphone; Heart Rate; Signal Processing, Computer-Assisted; Oximetry; Oxygen
PubMed: 36679533
DOI: 10.3390/s23020737 -
Heart, Lung & Circulation Feb 2021With the recognised physiologic value of dual chamber pacing, there was, at the commencement of the 1980s, an intense search for sensors to enable ventricular pacemakers... (Review)
Review
With the recognised physiologic value of dual chamber pacing, there was, at the commencement of the 1980s, an intense search for sensors to enable ventricular pacemakers to alter the pulse repetition rate in response to physiologic demand. Manufacturers fell into two main groups; those who chose highly physiologic sensors often requiring special pacing leads and those whose sensors allowed a standard pacing lead. Thirteen (13) sensors for rate adaptive pacing progressed at least to human investigational studies. Eventually the activity sensor, which responded quickly to exercise, but not to emotional stimuli or pyrexia and used a standard lead would predominate, with all manufacturers eventually accepting what was the least physiologic sensor investigated. The activity-based rate response was not dependent on cardiac or pulmonary disease, which could nullify the response with many of the other sensors. Three (3) other sensors survived that period and are still available today; minute ventilation, closed loop stimulation and central venous temperature, with the first two incorporated with activity as dual sensor systems. This review will outline the development of all the sensors used for rate adaptive pacing.
Topics: Arrhythmias, Cardiac; Australia; Cardiac Pacing, Artificial; Equipment Design; Heart Rate; History, 20th Century; Humans; Pacemaker, Artificial
PubMed: 33032894
DOI: 10.1016/j.hlc.2020.08.023 -
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 Medical Engineering &... Apr 2023Heart rate variability (HRV) extracted from the electrocardiogram (ECG) is an essential indicator for assessing the autonomic nervous system in clinical. Some scholars...
Heart rate variability (HRV) extracted from the electrocardiogram (ECG) is an essential indicator for assessing the autonomic nervous system in clinical. Some scholars have studied the feasibility of pulse rate variability (PRV) instead of HRV. However, there is little qualitative research in different body states. In this paper, the photoplethysmography (PPG) of postauricular and finger and the ECG of fifteen subjects were synchronously collected for comparative analysis. The eleven experiments were designed according to the daily living state, including the stationary state, limb movement state, and facial movement state. The substitutability of nine variables was investigated in the time, frequency, and nonlinearity domain by Passing Bablok regression and Bland Altman analysis. The results showed that the PPG of the finger was destroyed in the limb movement state. There were six variables of postauricular PRV, which showed a positive linear relationship and good agreement ( > 0.05, ratio 0.2) with HRV in all experiments. Our study suggests that the postauricular PPG could retain the necessary information of the pulse signal under the limb movement state and facial movement state. Therefore, postauricular PPG could be a better substitute for HRV, daily PPG detection, and mobile health than finger PPG.
Topics: Humans; Heart Rate; Healthy Volunteers; Photoplethysmography; Electrocardiography; Autonomic Nervous System
PubMed: 36794319
DOI: 10.1080/03091902.2023.2175061 -
IEEE Transactions on Bio-medical... Feb 2022Nocturnal recordings of heart rate and respiratory rate usually require several separate sensors or electrodes attached to different body parts - a disadvantage for...
OBJECTIVE
Nocturnal recordings of heart rate and respiratory rate usually require several separate sensors or electrodes attached to different body parts - a disadvantage for at-home screening tests and for large cohort studies. In this paper, we demonstrate that a state-of-the-art accelerometer placed at subjects' wrists can be used to derive reliable signal reconstructions of heartbeat (pulse wave intervals) and respiration during sleep.
METHODS
Based on 226 full-night recordings, we evaluate the performance of our signal reconstruction methodology with respect to polysomnography. We use a phase synchronization analysis metrics that considers individual heartbeats or breaths.
RESULTS
The quantitative comparison reveals that pulse-wave signal reconstructions are generally better than respiratory signal reconstructions. The best quality is achieved during deep sleep, followed by light sleep N2 and REM sleep. In addition, a suggested internal evaluation of multiple derived reconstructions can be used to identify time periods with highly reliable signals, particularly for pulse waves. Furthermore, we find that pulse-wave reconstructions are hardly affected by apnea and hypopnea events.
CONCLUSION
During sleep, pulse wave and respiration signals can simultaneously be reconstructed from the same accelerometer recording at the wrist without the need for additional sensors. Reliability can be increased by internal evaluation if the reconstructed signals are not needed for the whole sleep duration.
SIGNIFICANCE
The presented methodology can help to determine sleep characteristics and improve diagnostics and treatment of sleep disorders in the subjects' normal sleep environment.
Topics: Accelerometry; Heart Rate; Humans; Reproducibility of Results; Respiration; Sleep; Wrist
PubMed: 34437055
DOI: 10.1109/TBME.2021.3107978 -
American Journal of Respiratory and... Sep 2022
Topics: Adult; Cardiovascular Diseases; Continuous Positive Airway Pressure; Coronary Artery Disease; Disorders of Excessive Somnolence; Heart Disease Risk Factors; Heart Rate; Humans; Risk Factors; Sleep Apnea, Obstructive; Sleepiness
PubMed: 35675563
DOI: 10.1164/rccm.202206-1050ED -
Annual International Conference of the... Jul 2023Contactless sensors embedded in the ambient environment have broad applications in unobtrusive, long-term health monitoring for preventative and personalized healthcare....
Contactless sensors embedded in the ambient environment have broad applications in unobtrusive, long-term health monitoring for preventative and personalized healthcare. Microwave radar sensors are an attractive candidate for ambient sensing due to their high sensitivity to physiological motions, ability to penetrate through obstacles and privacy-preserving properties, but practical applications in complex real-world environments have been limited because of challenges associated with background clutter and interference. In this work, we propose a thin and soft textile sensor based on microwave metamaterials that can be easily integrated into ordinary furniture for contactless ambient monitoring of multiple cardiovascular signals in a localized manner. Evaluations of our sensor's performance in human subjects show high accuracy of heartbeat and arterial pulse detection, with ≥ 96.5% sensitivity and < 5% mean absolute relative error (MARE) across all subjects. We demonstrate our sensor's utility for cuffless blood pressure monitoring on a human subject over a continuous 10-minute period. Our results highlight the potential of metamaterial textile sensors in ambient health and wellness monitoring applications.Clinical relevance-The contactless metamaterial textile sensors demonstrated in this paper provide unobtrusive, convenient and long-term monitoring of multiple cardiovascular health metrics, including heart rate, pulse rate and cuffless blood pressure, which can facilitate preventative and personalized healthcare.
Topics: Humans; Monitoring, Physiologic; Textiles; Heart Rate; Wearable Electronic Devices; Vital Signs
PubMed: 38082876
DOI: 10.1109/EMBC40787.2023.10340864 -
Telemedicine Journal and E-health : the... Jun 2023Photoplethysmography (PPG) sensors have been increasingly used for remote patient monitoring, especially during the COVID-19 pandemic, for the management of chronic... (Review)
Review
Photoplethysmography (PPG) sensors have been increasingly used for remote patient monitoring, especially during the COVID-19 pandemic, for the management of chronic diseases and neurological disorders. There is an urgent need to evaluate the accuracy of these devices. This scoping review considers the latest applications of wearable PPG sensors with a focus on studies that used wearable PPG sensors to monitor various health parameters. The primary objective is to report the accuracy of the PPG sensors in both real-world and clinical settings. This scoping review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). Studies were identified by querying the Medline, Embase, IEEE, and CINAHL databases. The goal was to capture eligible studies that used PPG sensors to monitor various health parameters for populations with a minimum of 30 participants, with at least some of the population having relevant health issues. A total of 2,996 articles were screened and 28 are included in this review. The health parameters and disorders identified and investigated in this study include heart rate and heart rate variability, atrial fibrillation, blood pressure (BP), obstructive sleep apnea, blood glucose, heart failure, and respiratory rate. An overview of the algorithms used, and their limitations is provided. Some of the barriers identified in evaluating the accuracy of multiple types of wearable devices include the absence of reporting standard accuracy metrics and a general paucity of studies with large subject size in real-world settings, especially for parameters such as BP.
Topics: Humans; COVID-19; Heart Rate; Pandemics; Photoplethysmography; Telemedicine; Wearable Electronic Devices
PubMed: 36288566
DOI: 10.1089/tmj.2022.0182 -
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 -
Respiratory Physiology & Neurobiology Oct 2020Lung function and vascular effects of expert trumpet performance has not been elucidated. Airway mechanics, gas exchange and cardiovascular function were investigated in...
Lung function and vascular effects of expert trumpet performance has not been elucidated. Airway mechanics, gas exchange and cardiovascular function were investigated in expert trumpeters during a challenging performance. Respiratory impedance was measured in expert trumpeters and violinist controls prior to and following performance. Electrocardiography, pulse oximetry, transcutaneous CO and pulse transit time were monitored continuously. Performance did not alter lung function or gas exchange, except for a reduction in transcutaneous CO in 14 expert trumpeters compared to 4 expert violinists. Heart rate variability and pulse transit time were significantly altered in the trumpeters only, associated with the performance ventilatory requirements with a weight to low frequency band reflecting elevated baroreflex feedback. Trumpet performance at an expert level does not have an acute effect on airway mechanics and gas exchange was maintained. Repetitive increased intrathoracic pressure during performance resulted in marked heart rate and vagal tone variability. This study reveals the high demands placed on autonomic modulation of the cardiac response to expert trumpet performance.
Topics: Adult; Autonomic Nervous System; Electrocardiography; Female; Heart Rate; Humans; Male; Music; Psychomotor Performance; Respiratory Function Tests; Respiratory Physiological Phenomena; Vagus Nerve; Young Adult
PubMed: 32679371
DOI: 10.1016/j.resp.2020.103493