Optical Heart Rate Monitor Research Articles

Feasibility of using wearable technology to monitor agitation and sleep in patients with Alzheimer’s dementia: Lessons learned

AbstractBackgroundIndividuals with Alzheimer’s dementia (AD) often go through a period of significant behavioral and psychological symptoms including agitation. This can lead to impaired daily functioning, prolongation of hospitalization, early institutionalization, and higher mortality. The integration of biomedical data acquisition systems and information technology enables continuous real‐time monitoring of physiological data in daily life.MethodThis feasibility study is part of a clinical trial that examines the effects of THC‐free CBD oil on agitation in patients with AD (NCT04436081), involves caregiver/care‐recipient dyads and the use of technology to capture agitation during a 14‐week period. Participants are given 2 Fitbit versa 2 (each includes a 3‐axis accelerometer and an optical heart rate monitor), a smartphone, a tablet, and a digital timer. Participants’ Fitbit are paired with their smartphone, while the caregivers’ FitBit is paired with their tablet. Participants include males/females over 50 years old, with the diagnosis of AD, a MMSE score ≤28 & ≥4, and agitation measured with an NPI agitation/aggression subscore >3. Each dyad completes 24 forms/questionnaires throughout the study electronically via provided apps. Caregivers are instructed to send a real time electronic alert when agitation episodes happen.ResultSo far, we have enrolled 26 dyads. For this report we have collected data on 22 participants with 140 million data points for limb movement and heart rate, and 969 nights of sleep data records. Overall compliance with wearable use was 77% of the time, with 82% in 11 participants, 65% in 8 participants and 32% in 3 participants. Compliance with electronic form/questionnaire completion was 87%. Electronic alert for agitation episodes were recorded by the caregivers only 50% of time.ConclusionThis study explores the feasibility and acceptability of using technology (wearables, electronic form data completion and submission, sleep, and real time agitation episode collection) for a 16‐week period in AD patients with agitation and their caregivers. We found high acceptability of wearing the Fitbit by AD patients with agitation. The primary issues interfering with data collection and device compliance were device battery life and memory, remembering to wear the device after charging, and technical fault in capturing the data.

Ergonomic risk and physiological assessment of plogging activity

Plogging, an environment friendly trash workout is a combination of jogging with litter collection. People who are involved in the plogging carry a baggage for collecting the litter. Walking with a weight on one side causes the opposite side of the body to engage for stability and are also exposed to repetitive bending during the activity. The purpose of this study is to evaluate the postural and physiological aspects of plogging activity. Thirty six subjects performed the litter collection in stoop, semi-squat, full squat and lunge postures respectively. Postures were analyzed using Rapid Entire Body Assessment (REBA). Physiological aspects of plogging, as well as a comparison of physical activity assessment during jogging and plogging, were investigated using a Polar M430 optical heart rate monitor. Statistical analysis were performed using SPSS version 23. Mean±SD of full squat (5.13±0.59) and lunge (6.64±1.15) posture was found to have lesser risk score in comparison with the other two postures such as stoop (10.31±0.88) and semi-squat (8.11±1.40). Analysis from the Kruskal-Wallis and post hoc test showed that there is no significant interaction between the postures (p < 0.05). Paired Sample t-test showed that the energy expenditure for plogging and jogging are found to be similar (p > 0.05), but the fat percentages of calories burned is more in plogging (p < 0.05). Howerver plogging can be considered as a strenous activity as the % Cardiovascular strain of the activity had a mean value of (99.261% ). Ergonomic interventions are needed to play a vital role in minimizing the musculoskeletal related injuries and the physical strain of the task.

Self-monitoring Support for Stress in the Environment of COVID-19 Infection Control Measures using an Optical Wearable Heart Rate Monitor

A system was developed to support self-monitoring for everyday life. One of the features of this system is that heart rate information is used as an objective judgment material of stress for participation in the activity of ICF environmental factors, which is a subjective judgment material of the situation. In order to obtain this heart rate information, we used an optical wearable terminal that is less accurate than the electrode type in consideration of non-invasiveness to various needs in daily life. Furthermore, Onomatopoeia icon based on ICF was used for subjective data entry. These enable the simple expression of one’s internal emotions and are widely used in sensitivity expression classifications in psychotherapy and tactile perception due to their ease of use. In this presentation, we will report on the basic research on self-monitoring support and its implementation throughout the year in a COVID-19 infection control environment.

Validation of Heart Rate Extracted From Wrist-Based Photoplethysmography in the Perioperative Setting: Prospective Observational Study.

BackgroundMeasurement of heart rate (HR) through an unobtrusive, wrist-worn optical HR monitor (OHRM) could enable earlier recognition of patient deterioration in low acuity settings and enable timely intervention.ObjectiveThe goal of this study was to assess the agreement between the HR extracted from the OHRM and the gold standard 5-lead electrocardiogram (ECG) connected to a patient monitor during surgery and in the recovery period.MethodsIn patients undergoing surgery requiring anesthesia, the HR reported by the patient monitor’s ECG module was recorded and stored simultaneously with the photopletysmography (PPG) from the OHRM attached to the patient’s wrist. The agreement between the HR reported by the patient’s monitor and the HR extracted from the OHRM’s PPG signal was assessed using Bland-Altman analysis during the surgical and recovery phase.ResultsA total of 271.8 hours of data in 99 patients was recorded simultaneously by the OHRM and patient monitor. The median coverage was 86% (IQR 65%-95%) and did not differ significantly between surgery and recovery (Wilcoxon paired difference test P=.17). Agreement analysis showed the limits of agreement (LoA) of the difference between the OHRM and the ECG HR were within the range of 5 beats per minute (bpm). The mean bias was –0.14 bpm (LoA between –3.08 bpm and 2.79 bpm) and –0.19% (LoA between –5 bpm to 5 bpm) for the PPG- measured HR compared to the ECG-measured HR during surgery; during recovery, it was –0.11 bpm (LoA between –2.79 bpm and 2.59 bpm) and –0.15% (LoA between –3.92% and 3.64%).ConclusionsThis study shows that an OHRM equipped with a PPG sensor can measure HR within the ECG reference standard of –5 bpm to 5 bpm or –10% to 10% in the perioperative setting when the PPG signal is of sufficient quality. This implies that an OHRM can be considered clinically acceptable for HR monitoring in low acuity hospitalized patients.

Accuracy of heart rate variability estimated with reflective wrist-PPG in elderly vascular patients

Optical heart rate monitoring (OHR) with reflective wrist photoplethysmography is a technique mainly used in the wellness application domain for monitoring heart rate levels during exercise. In the absence of motion, OHR technique is also able to estimate individual beat-to-beat intervals relatively well and can therefore also be used, for example, in monitoring of cardiac arrhythmias, stress, or sleep quality through heart rate variability (HRV) analysis. HRV analysis has also potential in monitoring the recovery of patients, e.g. after a medical intervention. However, in order to detect subtle changes, the calculated HRV parameters should be sufficiently accurate and very few studies exist that asses the accuracy of OHR derived HRV in non-healthy subjects. In this paper, we present a method to estimate beat-to-beat-intervals (BBIs) from reflective wrist PPG signal and evaluated the accuracy of the proposed method in estimating BBIs in a cross-sectional study with 29 hospitalized patients (mean age 70.6 years) in 24-h recordings performed after peripheral vascular surgery or endovascular interventions. Finally, we evaluate the accuracy of more than 30 commonly used HRV parameters and find that the accuracy of certain metrics, for example SDNN and triangular index, shown in the literature to be associated with the deterioration of the status of the patients during recovery from surgical intervention, could be adequate for patient monitoring. On the other hand, the parameters more affected by the high-frequency content of the HRV and especially the LF/HF-ratio should be used with caution.

Challenging the Limitations of Atrial Fibrillation Detection in the Presence of Other Cardiac Arrythmias.

Atrial fibrillation (AF) affects millions of people worldwide and needs to be diagnosed in its early stage to provide proper treatment. However, the numerous wearable devices available today are not yet able to discriminate AF episodes from other cardiac arrhythmias and merely detect normal vs abnormal rhythms.In this study we investigated the performance of a traditional classifier - designed to distinguish AF and sinus rhythm (SR) using inter-beat intervals (IBI) - when confronted with other - non-AF - arrhythmias. This classifier was challenged with data of 37 patients wearing an optical heart rate monitor device during catheter ablation procedures. We first analyzed the classification performance of pure AF vs SR and then gradually introduced non-AF arrhythmias in the time windows used for classification.We obtained a high classification performance (accuracy, sensitivity and specificity of 0.979, 1.000 and 0.966) for purely AF and SR. In contrast, when increasing the maximal possible number of non-AF arrhythmias to 50%, the performance decreased to an accuracy, sensitivity and specificity of 0.886, 0.998 and 0.853. While sinus tachycardia led to false positives the classification was not impaired by the presence of extrasystoles, bigeminy, bradycardia, frequent ectopic beats or atrial flutter.Our study quantifies to what extent a traditional IBI-based classifier is not sufficient to distinguish AF from other arrhythmias. Future work should concentrate on acquiring datasets with a high diversity of arrhythmias and employing new classification features.

Using consumer-wearable technology for remote assessment of physiological response to stress in the naturalistic environment.

Psychosocial stress is a major risk factor for morbidity and mortality related to a wide range of health conditions and has a significant negative impact on public health. Quantifying exposure to stress in the naturalistic environment can help to better understand its health effects and identify strategies for timely intervention. The objective of the current project was to develop and test the infrastructure and methods necessary for using wearable technology to quantify individual response to stressful situations and to determine if popular and accessible fitness trackers such as Fitbit® equipped with an optical heart rate (HR) monitor could be used to detect physiological response to psychosocial stress in everyday life. The participants in this study were University of Minnesota students (n = 18) that owned a Fitbit® tracker and had at least one upcoming examination. Continuous HR and activity measurements were obtained during a 7-day observation period containing examinations self-reported by the participants. Participants responded to six ecological momentary assessment surveys per day (~ 2 hour intervals) to indicate occurrence of stressful events. We compared HR during stressful events (e.g., exams) to baseline HR during periods indicated as non-stressful using mixed effects modeling. Our results show that HR was elevated by 8.9 beats per minute during exams and by 3.2 beats per minute during non-exam stressors. These results are consistent with prior laboratory findings and indicate that consumer wearable fitness trackers could serve as a valuable source of information on exposure to psychosocial stressors encountered in the naturalistic environment.

Validation of Polar OH1 optical heart rate sensor for moderate and high intensity physical activities.

BackgroundOptical measurement techniques and recent advances in wearable technology have made heart rate (HR) sensing simpler and more affordable.ObjectivesThe Polar OH1 is an arm worn optical heart rate monitor. The objectives of this study are two-fold; 1) to validate the OH1 optical HR sensor with the gold standard of HR measurement, electrocardiography (ECG), over a range of moderate to high intensity physical activities, 2) to validate wearing the OH1 at the temple as an alternative location to its recommended wearing location around the forearm and upper arm.MethodsTwenty-four individuals participated in a physical exercise protocol, by walking on a treadmill and riding a stationary spin bike at different speeds while the criterion measure, ECG and Polar OH1 HR were recorded simultaneously at three different body locations; forearm, upper arm and the temple. Time synchronised HR data points were compared using Bland-Altman analyses and intraclass correlation.ResultsThe intraclass correlation between the ECG and Polar OH1, for the aggregated data, was 0.99 and the estimated mean bias ranged 0.27–0.33 bpm for the sensor locations. The three sensors exhibited a 95% limit of agreement (LoA: forearm 5.22, -4.68 bpm; upper arm 5.15, -4.49; temple 5.22, -4.66). The mean of the ECG HR for the aggregated data was 112.15 ± 24.52 bpm. The intraclass correlation of HR values below and above this mean were 0.98 and 0.99 respectively. The reported mean bias ranged 0.38–0.47 bpm (95% LoA: forearm 6.14, -5.38 bpm; upper arm 6.07, -5.13 bpm; temple 6.09, -5.31 bpm), and 0.15–0.16 bpm (95% LoA: forearm 3.99, -3.69 bpm; upper arm 3.90, -3.58 bpm; temple 4.06, -3.76 bpm) respectively. During different exercise intensities, the intraclass correlation ranged 0.95–0.99 for the three sensor locations. During the entire protocol, the estimated mean bias was in the range -0.15–0.55 bpm, 0.01–0.53 bpm and -0.37–0.48 bpm, for the forearm, upper arm and temple locations respectively. The corresponding upper limits of 95% LoA were 3.22–7.03 bpm, 3.25–6.82 bpm and 3.18–7.04 bpm while the lower limits of 95% LoA were -6.36–(-2.35) bpm, -6.46–(-2.30) bpm and -7.42–(-2.41) bpm.ConclusionPolar OH1 demonstrates high level of agreement with the criterion measure ECG HR, thus can be used as a valid measure of HR in lab and field settings during moderate and high intensity physical activities.

Wrist-worn optical and chest strap heart rate comparison in a heterogeneous sample of healthy individuals and in coronary artery disease patients

BackgroundThe need for unobtrusive HR (heart rate) monitoring has led to the development of a new generation of strapless HR monitors. The aim of this study was to determine whether such an unobtrusive, wrist-worn optical HR monitor (OHRM) could be equivalent and therefore a valid alternative to a traditional chest strap during a broad range of activities in a heterogeneous healthy population and coronary artery disease (CAD) patients.MethodsOne hundred ninety-nine healthy volunteers, 84 males and 115 females, including 35 overweight-obese subjects, 53 pregnant women, and 20 CAD patients were tested in the present study. Second-by-second HR measured by the OHRM was concurrently evaluated against an ECG-based chest strap monitor during a broad range of activities (i.e., walking, running, cycling, gym, household, and sedentary activities).ResultsData coverage, percentage of time the OHRM provides a HR not larger than 10 bpm from the reference, went from a minimum of 92% of the time in the least periodic activity (i.e., gym), to 95% during the most intense activity (i.e., running), and to a maximum of 98% for sedentary activities. The limits of agreement of the difference between the OHRM and the chest strap HR were within the range of ±15 bpm. The OHRM showed a concordance correlation coefficient of 0.98. Overall, the mean absolute error was not larger than 3 bpm, which can be considered clinically acceptable for a number of applications. A similar performance was found for CAD (94.2% coverage, 2.4 bpm error), but the small sample size does not allow any quantitative comparison.ConclusionHeart rate measured by OHRM at the wrist and ECG-based HR measured via a traditional chest strap are acceptably close in a broad range of activities in a heterogeneous, healthy population, and showed initial promising results also in CAD patients.

P 083 - The effect of a bespoke home based physical activity intervention on markers of oxidative stress and markers of general health in older adults

Home-based unsupervised exercise training has been shown to improve health in older adults. Assessing adherence, especially using a self-report format, in unsupervised exercise interventions is problematic. The aim of this pilot study was to objectively assess the effect of an unsupervised home-based exercise intervention in community dwelling older adults. Markers of oxidative stress and measures of health were assessed, including cerebral hemodynamics and cognitive function. Physical activity was measured continuously using a wrist watch type accelerometer with optical heart rate monitoring. A secondary aim of the study was to test the feasibility of a wrist activity monitor as a tool to assess physical activity in this population. The intervention failed to increase the level of physical activity in all the participants, although changes were observed. No significant changes were observed in markers of oxidative stress or other measures of health in response to the exercise intervention. Progressive goals, based on adherence measurement, are potentially important for the success of an unsupervised exercise intervention. Wrist-based accelerometers may be useful tools for the assessment of physical activity in sedentary older adults, but further development of specialist software may be necessary.

Reliability evaluation of an wearable consumer optical heart rate monitor

Reliability evaluation of an wearable consumer optical heart rate monitor

Reliability evaluation of an wearable consumer optical heart rate monitor

Reliability evaluation of an wearable consumer optical heart rate monitor

Towards 24/7 continuous heart rate monitoring.

Heart rate (HR) and HR variability (HRV) carry rich information about physical activity, mental and physical load, physiological status, and health of an individual. When combined with activity monitoring and personalized physiological modelling, HR/HRV monitoring may be used for monitoring of complex behaviors and impact of behaviors and external factors on the current physiological status of an individual. Optical HR monitoring (OHR) from wrist provides a comfortable and unobtrusive method for HR/HRV monitoring and is better adhered by users than traditional ECG electrodes or chest straps. However, OHR power consumption is significantly higher than that for ECG based methods due to the measurement principle based on optical illumination of the tissue. We developed an algorithmic approach to reduce power consumption of the OHR in 24/7 HR trending. We use continuous activity monitoring and a fast converging frequency domain algorithm to derive a reliable HR estimate in 7.1s (during outdoor sports, in average) to 10.0s (during daily life). The method allows >80% reduction in power consumption in 24/7 OHR monitoring when average HR monitoring is targeted, without significant reduction in tracking accuracy.

Evaluation of accuracy and reliability of PulseOn optical heart rate monitoring device.

PulseOn is a wrist-worn optical heart rate (HR) monitor based on photoplethysmography. It utilizes multi-wavelength technology and optimized sensor geometry to monitor blood flow at different depths of skin tissue, and it dynamically adapts to an optimal measurement depth in different conditions. Movement artefacts are reduced by adaptive movement-cancellation algorithms and optimized mechanics, which stabilize the sensor-to-skin contact. In this paper, we evaluated the accuracy and reliability of PulseOn technology against ECG-derived HR in laboratory conditions during a wide range of physical activities and also during outdoor sports. In addition, we compared the performance to another on-the-shelf wrist-worn consumer product Mio LINK(®). The results showed PulseOn reliability (% of time with error <;10bpm) of 94.5% with accuracy (100% - mean absolute percentage error) 96.6% as compared to ECG (vs 86.6% and 94.4% for Mio LINK(®), correspondingly) during laboratory protocol. Similar or better reliability and accuracy was seen during normal outdoor sports activities. The results show that PulseOn provides reliability and accuracy similar to traditional chest strap ECG HR monitors during cardiovascular exercise.

Application of flexible flat panel display technology to wearable biomedical devices

How the application of commercial (thin film) flat panel display technology, used in the production of flexible displays and flexible digital X-ray detectors, can also be applied to reduce the manufacturing cost of wearable biomedical devices, as well as potentially improve their diagnostic functionality, is explored. As a technology platform to evaluate the presented new concept, a prototype photoplethysmograph biosensor using a flexible organic light-emitting diode display and pin photodiode (thin film) sensor technology for optical heart rate monitoring is developed.