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Sensors (Basel, Switzerland) Aug 2022The paper presents a wearable sensor for breath and pulse monitoring using an inertial sensor and episodic broadcast radio transmission. The data transmission control...
The paper presents a wearable sensor for breath and pulse monitoring using an inertial sensor and episodic broadcast radio transmission. The data transmission control algorithm applied allows for the transmission of additional information using the standard PDU format and, at the same time, goes beyond the Bluetooth teletransmission standard (BLE). The episodic broadcast transmission makes it possible to receive information from sensors without the need to create a dedicated radio link or a defined network structure. The radio transmission controlled by the occurrence of a specific event in the monitored signal is combined with the reference wire transmission. The signals from two different types of sensors and the simulated ECG signal are used to control the BLE transmission. The presented results of laboratory tests indicate the effectiveness of episodic data transmission in the BLE standard. The conducted analysis showed that the mean difference in pulse detection using the episodic transmission compared to the wire transmission is 0.038 s, which is about 4% of the mean duration of a single cycle, assuming that the average adult human pulse is 60 BPM.
Topics: Adult; Algorithms; Heart Rate; Humans; Monitoring, Physiologic; Respiration
PubMed: 36015777
DOI: 10.3390/s22166019 -
PloS One 2023Proteinoids are thermal proteins which swell into microspheres in aqueous solution. Ensembles of proteinoids produce electrical spiking activity similar to that of...
Proteinoids are thermal proteins which swell into microspheres in aqueous solution. Ensembles of proteinoids produce electrical spiking activity similar to that of neurons. We introduce a novel method for implementing logical gates in the ensembles of proteinoid microspheres using chronoamperometry. Chronoamperometry is a technique that involves applying a voltage pulse to proteinoid microspheres and measuring their current response. We have observed that proteinoids exhibit distinct current patterns that align with various logical outputs. We identify four types of logical gates: AND, OR, XOR, and NAND. These gates are determined by the current response of proteinoid microspheres. Additionally, we demonstrate that proteinoid microspheres have the ability to modify their current response over time, which is influenced by their previous exposure to voltage. This indicates that they possess a capacity for learning and are capable of adapting to their environment. Our research showcases the ability of proteinoid microspheres to perform logical operations and computations through their inherent electrical properties.
Topics: Microspheres; Heart Rate; Learning; Neurons
PubMed: 37721941
DOI: 10.1371/journal.pone.0289433 -
The Journal of Pediatrics Jan 2023To evaluate parents' ability to accurately assess their child's heart and respiratory rates (RRs) in the context of potential utility for telehealth visits.
OBJECTIVE
To evaluate parents' ability to accurately assess their child's heart and respiratory rates (RRs) in the context of potential utility for telehealth visits.
STUDY DESIGN
In this controlled study of 203 child-parent pairs, parents measured their child's heart rate (HR) using 4 methods: palpation, auscultation, and 2 photoplethysmographic smartphone applications. Parents measured RR by inspecting the child and tapping the smartphone application. The gold standards were electrocardiogram for the HR and the child's breaths measured by a health care professional for 60 seconds for the RR. We plotted the measurements using a Bland-Altman plot with 95% limits of agreement.
RESULTS
Parents underestimated HR by palpation with a calculated bias of -18 beats per minute (bpm) (SD, 19), with limits of agreement ranging from -56 to 19 bpm. Parents overestimated and underestimated HR by auscultation with limits of agreement ranging from -53 to 46 bpm. Smartphone applications did not improve the accuracy of measurements. The accuracy of parental RR measurements was low. For young children, bias was -0.8 breaths per minute (brpm) (SD, 9.8) with limits of agreement from -20 to 19 brpm, and for older children, bias was 0.9 brpm (SD 7.4) with limits of agreement from 6 to 15 brpm. The sensitivity of parental subjective opinion to recognize accelerated RR was 37% (95% CI, 25%-51%).
CONCLUSION
Parents were not able to assess their child's RR or HR accurately. Digital remote assessment of children should not rely on parental measurements of vital signs.
Topics: Child; Humans; Adolescent; Child, Preschool; Parents; Vital Signs; Respiratory Rate; Heart Rate; Electrocardiography
PubMed: 35973446
DOI: 10.1016/j.jpeds.2022.08.018 -
Journal of Hypertension Jan 2021When assessing arterial stiffness, heart rate (HR) and blood pressure (BP) are potential confounders. It appears that the HR/BP dependences of pulse wave velocity (PWV)...
OBJECTIVES
When assessing arterial stiffness, heart rate (HR) and blood pressure (BP) are potential confounders. It appears that the HR/BP dependences of pulse wave velocity (PWV) and distensibility are different, even though both assess arterial stiffness. This study aims to compare aortic PWV as measured using pulse transit time (PWVTT) and as calculated from distensibility (PWVdist) at the same measurement site and propose a solution to the disparity in dependences of PWVTT and PWVdist.
METHODS
Adult anaesthetized rats (n = 24) were randomly paced at HRs 300-500 bpm, at 50 bpm steps. At each step, aortic PWVTT (two pressure-tip catheters) and PWVdist (pressure-tip catheter and ultrasound wall-tracking; abdominal aorta) were measured simultaneously while BP was varied pharmacologically.
RESULTS
HR dependence of PWVdist paradoxically decreased at higher levels of BP. In addition, BP dependence of PWVdist was much larger than that of PWVTT. These discrepancies are explained in that standard PWVdist uses an approximate derivative of pressure to diameter, which overestimates PWV with increasing pulse pressure (PP). In vivo, PP decreases as HR increases, potentially causing a PWVdist decrease with HR. Estimating the full pressure-diameter curve for each HR corrected for this effect by enabling calculation of the true derivative at diastolic BP. This correction yielded a PWVdist that shows HR and BP dependences similar to those of PWVTT. As expected, BP dependence of all PWV metrics was much larger than HR dependence.
CONCLUSION
Measured and calculated PWV have different dependences on HR and BP. These differences are, at least in part, because of approximations made in using systolic and diastolic values to calculate distensibility.
Topics: Animals; Aorta; Blood Pressure; Heart Rate; Pulse Wave Analysis; Rats; Vascular Stiffness
PubMed: 32784350
DOI: 10.1097/HJH.0000000000002608 -
The Western Journal of Emergency... Oct 2020The American Heart Association Guidelines for Cardiopulmonary Resuscitation (CPR) recommend pulse checks of less than 10 seconds. We assessed the effect of video...
INTRODUCTION
The American Heart Association Guidelines for Cardiopulmonary Resuscitation (CPR) recommend pulse checks of less than 10 seconds. We assessed the effect of video review-based educational feedback on pulse check duration with and without point-of-care ultrasound (POCUS).
METHODS
Cameras recorded cases of CPR in the emergency department (ED). Investigators reviewed resuscitation videos for ultrasound use during pulse check, pulse check duration, and compression-fraction ratio. Investigators reviewed health records for patient outcomes. Providers received written feedback regarding pulse check duration and compression-fraction ratio. Researchers reviewed selected videos in multidisciplinary grand round presentations, with research team members facilitating discussion. These presentations highlighted strategies that include the following: limit on pulse check duration; emphasis on compressions; and use of "record, then review" method for pulse checks with POCUS. The primary endpoint was pulse check duration with and without POCUS.
RESULTS
Over 19 months, investigators reviewed 70 resuscitations with a total of 325 pulse checks. The mean pulse check duration was 11.5 ± 8.8 seconds (n = 224) and 13.8 ± 8.6 seconds (n = 101) without and with POCUS, respectively. POCUS pulse checks were significantly longer than those without POCUS (P = 0.001). Mean pulse check duration per three-month block decreased statistically significantly from study onset to the final study period (from 17.2 to 10 seconds [P<0.0001]) overall; decreased from 16.6 to 10.5 seconds (P<0.0001) without POCUS; and with POCUS from 19.8 to 9.88 seconds (P<0.0001) with POCUS. Pulse check times decreased significantly over the study period of educational interventions. The strongest effect size was found in POCUS pulse check duration (P = -0.3640, P = 0.002).
CONCLUSION
Consistent with previous studies, POCUS prolonged pulse checks. Educational interventions were associated with significantly decreased overall pulse-check duration, with an enhanced effect on pulse checks involving POCUS. Performance feedback and video review-based education can improve CPR by increasing chest compression-fraction ratio.
Topics: Aged; American Heart Association; Cardiopulmonary Resuscitation; Education, Medical, Graduate; Emergency Service, Hospital; Female; Heart Rate; Humans; Male; Middle Aged; Monitoring, Physiologic; Time Factors; Ultrasonography; United States; Video Recording
PubMed: 33207177
DOI: 10.5811/westjem.2020.8.47876 -
Investigative Ophthalmology & Visual... Apr 2020To study the effect of changing heart rate on the ocular pulse and the dynamic biomechanical behavior of the optic nerve head (ONH) using a comprehensive mathematical...
PURPOSE
To study the effect of changing heart rate on the ocular pulse and the dynamic biomechanical behavior of the optic nerve head (ONH) using a comprehensive mathematical model.
METHODS
In a finite element model of a healthy eye, a biphasic choroid consisted of a solid phase with connective tissues and a fluid phase with blood, and the lamina cribrosa (LC) was viscoelastic as characterized by a stress-relaxation test. We applied arterial pressures at 18 ocular entry sites (posterior ciliary arteries), and venous pressures at four exit sites (vortex veins). In the model, the heart rate was varied from 60 to 120 bpm (increment: 20 bpm). We assessed the ocular pulse amplitude (OPA), pulse volume, ONH deformations, and the dynamic modulus of the LC at different heart rates.
RESULTS
With an increasing heart rate, the OPA decreased by 0.04 mm Hg for every 10 bpm increase in heart rate. The ocular pulse volume decreased linearly by 0.13 µL for every 10 bpm increase in heart rate. The storage modulus and the loss modulus of the LC increased by 0.014 and 0.04 MPa, respectively, for every 10 bpm increase in heart rate.
CONCLUSIONS
In our model, the OPA, pulse volume, and ONH deformations decreased with an increasing heart rate, whereas the LC became stiffer. The effects of blood pressure/heart rate changes on ONH stiffening may be of interest for glaucoma pathology.
Topics: Animals; Biomechanical Phenomena; Finite Element Analysis; Glaucoma; Heart Rate; Humans; Intraocular Pressure; Models, Biological; Models, Theoretical; Optic Disk; Sensitivity and Specificity; Tonometry, Ocular
PubMed: 32315378
DOI: 10.1167/iovs.61.4.27 -
Computer Methods and Programs in... Jun 2022Consumer-level cameras have provided an advantage of designing cost-effective, non-contact physiological parameters estimation approaches which is not possible with gold... (Review)
Review
BACKGROUND
Consumer-level cameras have provided an advantage of designing cost-effective, non-contact physiological parameters estimation approaches which is not possible with gold standard estimation techniques. This encourages the development of non-contact estimation methods using camera technology. Therefore, this work aims to present a systematic review summarizing the currently existing face-based non-contact methods along with their performance.
METHODS
This review includes all heart rate (HR) and oxygen saturation (SpO2) studies published in journals and a few reputed conferences, which have compared the proposed estimation methods with one or more standard reference devices. The articles were collected from the following research databases: Institute of Electrical and Electronics Engineers (IEEE), PubMed, Web of Science (WoS), Science Direct, and Association of Computer Machinery (ACM) digital library. All database searches were completed on May 20, 2021. Each study was assessed using a finite set of identified factors for reporting bias.
RESULTS
Out of 332 identified studies, 32 studies were selected for the final review. Additionally, 18 studies were included by thoroughly checking these studies. 3 out of 50 (6%) studies were performed in clinical conditions, while the remaining studies were carried out on a healthy population. 42 out of 50 (84%) studies have estimated HR, while 5/50 (10%) studies have measured SpO only. The remaining three studies have estimated both parameters. The majority of the studies have used 1-3 min videos for estimation. Among the estimation methods, Deep Learning and Independent component analysis (ICA) were used by 11/42 (26.19%) and 9/42 (21.42%) studies, respectively. According to the Bland-Altman analysis, only 8/45 (17.77%) HR studies achieved the clinically accepted error limits whereas, for SpO, 4/5 (80%) studies have matched the industry standards (±3%).
DISCUSSION
Deep Learning and ICA have been predominantly used for HR estimations. Among deep learning estimation methods, convolutional neural networks have been employed till date due to their good generalization ability. Most non-contact HR estimation methods need significant improvements to implement these methods in a clinical environment. Furthermore, these methods need to be tested on the subjects suffering from any related disease. SpO estimation studies are challenging and need to be tested by conducting hypoxemic events. The authors would encourage reporting the detailed information about the study population, the use of longer videos, and appropriate performance metrics and testing under abnormal HR and SpO ranges for future estimation studies.
Topics: Face; Heart Rate; Humans; Oxygen Saturation
PubMed: 35390724
DOI: 10.1016/j.cmpb.2022.106771 -
Sensors (Basel, Switzerland) Oct 2022With the recent advancements in the field of wearable technologies, the opportunity to monitor stress continuously using different physiological variables has gained...
With the recent advancements in the field of wearable technologies, the opportunity to monitor stress continuously using different physiological variables has gained significant interest. The early detection of stress can help improve healthcare and minimizes the negative impact of long-term stress. This paper reports outcomes of a pilot study and associated stress-monitoring dataset, named the "Stress-Predict Dataset", created by collecting physiological signals from healthy subjects using wrist-worn watches with a photoplethysmogram (PPG) sensor. While wearing these watches, 35 healthy volunteers underwent a series of tasks (i.e., Stroop color test, Trier Social Stress Test and Hyperventilation Provocation Test), along with a rest period in-between each task. They also answered questionnaires designed to induce stress levels compatible with daily life. The changes in the blood volume pulse (BVP) and heart rate were recorded by the watch and were labelled as occurring during stress-inducing tasks or a rest period (no stress). Additionally, respiratory rate was estimated using the BVP signal. Statistical models and personalised adaptive reference ranges were used to determine the utility of the proposed stressors and the extracted variables (heart rate and respiratory rate). The analysis showed that the interview session was the most significant stress stimulus, causing a significant variation in heart rate of 27 (77%) participants and respiratory rate of 28 (80%) participants out of 35. The outcomes of this study contribute to the understanding the role of stressors and their association with physiological response and provide a dataset to help develop new wearable solutions for more reliable, valid, and sensitive physio-logical stress monitoring.
Topics: Humans; Pilot Projects; Wearable Electronic Devices; Heart Rate; Monitoring, Physiologic; Respiratory Rate; Photoplethysmography
PubMed: 36365837
DOI: 10.3390/s22218135 -
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