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Sensors (Basel, Switzerland) Aug 2023Over the past few years, there has been increased interest in photoplethysmography (PPG) technology, which has revealed that, in addition to heart rate and oxygen...
Over the past few years, there has been increased interest in photoplethysmography (PPG) technology, which has revealed that, in addition to heart rate and oxygen saturation, the pulse shape of the PPG signal contains much more valuable information. Lately, the wearable market has shifted towards a multi-wavelength and multichannel approach to increase signal robustness and facilitate the extraction of other intrinsic information from the signal. This transition presents several challenges related to complexity, accuracy, and reliability of algorithms. To address these challenges, anomaly detection stages can be employed to increase the accuracy and reliability of estimated parameters. Powerful algorithms, such as lightweight machine learning (ML) algorithms, can be used for anomaly detection in multi-wavelength PPG (MW-PPG). The main contributions of this paper are proposing a set of features with high information gain for anomaly detection in MW-PPG signals in the classification context, assessing the impact of window size and evaluating various lightweight ML models to achieve highly accurate anomaly detection, and examining the effectiveness of MW-PPG signals in detecting artifacts.
Topics: Photoplethysmography; Reproducibility of Results; Algorithms; Heart Rate; Machine Learning; Artifacts; Signal Processing, Computer-Assisted
PubMed: 37571730
DOI: 10.3390/s23156947 -
Science Advances Aug 2023Continuous and reliable monitoring of blood pressure and cardiac function is of great importance for diagnosing and preventing cardiovascular diseases. However, existing...
Continuous and reliable monitoring of blood pressure and cardiac function is of great importance for diagnosing and preventing cardiovascular diseases. However, existing cardiovascular monitoring approaches are bulky and costly, limiting their wide applications for early diagnosis. Here, we developed an intelligent blood pressure and cardiac function monitoring system based on a conformal and flexible strain sensor array and deep learning neural networks. The sensor has a variety of advantages, including high sensitivity, high linearity, fast response and recovery, and high isotropy. Experiments and simulation synergistically verified that the sensor array can acquire high-precise and feature-rich pulse waves from the wrist without precise positioning. By combining high-quality pulse waves with a well-trained deep learning model, we can monitor blood pressure and cardiac function parameters. As a proof of concept, we further constructed an intelligent wearable system for real-time and long-term monitoring of blood pressure and cardiac function, which may contribute to personalized health management, precise and early diagnosis, and remote treatment.
Topics: Wearable Electronic Devices; Blood Pressure; Deep Learning; Monitoring, Physiologic; Heart Rate
PubMed: 37566652
DOI: 10.1126/sciadv.adh0615 -
Respiratory Physiology & Neurobiology Sep 2023We aimed to investigate respiratory rate variability (RRV) and tidal volume (V) variability during exposure to normobaric hypoxia (i.e., reduction in the fraction of...
PURPOSE
We aimed to investigate respiratory rate variability (RRV) and tidal volume (V) variability during exposure to normobaric hypoxia (i.e., reduction in the fraction of inspired oxygen - FiO), and the association of the changes in RRV and V variability with the changes in pulse oxygen saturation (SpO).
METHODS
Thirty healthy human participants (15 females) were exposed to: (1) 15-min normoxia, (2) 10-min hypoxia simulating 2200 m, (3) 10-min hypoxia simulating 4000 m, (4) 10-min hypoxia simulating 5000 m, (5) 15-min recovery in normoxia. Linear regression modelling was applied with SpO (dependent variable) and the changes in RRV and V variability (independent variables), controlling for FiO, age, sex, changes in heart rate (HR), changes in HR variability (HRV), and changes in minute ventilation (V).
RESULTS
When modelling breathing parameter variability as root-mean-square standard deviation (RMSSD), a significant independent association of the changes in RRV with the changes in SpO was found (B = -4.3e-04, 95% CI = -8.3e-04/-2.1e-05, p = 0.04). The changes in V variability showed no significant association with the changes in SpO (B = -1.6, 95% CI = -5.5/2.4, p = 0.42). When modelling parameters variability as SD, a significant independent association of the changes in RRV with the changes in SpO was found (B = -8.2e-04, 95% CI = -1.5e-03/-9.4e-05, p = 0.03). The changes in V variability showed no significant association with the changes in SpO (B=1.4, 95% CI = -5.8/8.6, p = 0.69).
CONCLUSION
Higher RRV is independently associated with lower SpO during acute hypoxic exposure, while V variability parameters are not. Therefore, RRV may be a potentially interesting parameter to characterize individual responses to acute hypoxia.
Topics: Female; Humans; Pilot Projects; Hypoxia; Respiration; Respiratory Rate; Heart Rate; Oxygen
PubMed: 37355056
DOI: 10.1016/j.resp.2023.104096 -
Journal of Rehabilitation Medicine Jun 2024To compare the estimation of time spent on 4 categories of physical activity intensity (sedentary behaviour, light physical activity, moderate physical activity, and... (Observational Study)
Observational Study Comparative Study
OBJECTIVE
To compare the estimation of time spent on 4 categories of physical activity intensity (sedentary behaviour, light physical activity, moderate physical activity, and vigorous physical activity) between a motion sensor and a heart rate monitor during a stroke outpatient rehabilitation session.
DESIGN
A multicentre cross-sectional observational study.
SUBJECTS/PATIENTS
Participants with stroke (> 6 months) undergoing outpatient rehabilitation sessions.
METHODS
Participants wore the SenseWear Armband motion sensor and the Polar H10 heart rate monitor during 2 rehabilitation sessions. The times estimated by each device were compared using a generalized linear mixed model and post-hoc tests.
RESULTS
Ninety-nine participants from 29 clinics were recruited and data from 146 sessions were included in the analysis. The estimated times depended on the devices and the physical activity intensity category (F = 135, p < 0.05). The motion sensor estimated more time spent in sedentary behaviour and less time spent in moderate physical activity and vigorous physical activity than the heart rate monitor.
CONCLUSION
The motion sensor and heart rate monitor provide different estimates of physical activity intensity during stroke rehabilitation. Further research is needed to establish the most appropriate device for each physical activity category.
Topics: Humans; Stroke Rehabilitation; Male; Female; Cross-Sectional Studies; Middle Aged; Heart Rate; Exercise; Aged; Stroke; Outpatients
PubMed: 38915294
DOI: 10.2340/jrm.v56.40559 -
Journal of the American Heart... Feb 2024The form factor (FF) is a pulse shape indicator that corresponds to the fraction of pulse pressure added to diastolic blood pressure to estimate the time-averaged mean...
BACKGROUND
The form factor (FF) is a pulse shape indicator that corresponds to the fraction of pulse pressure added to diastolic blood pressure to estimate the time-averaged mean arterial pressure (MAP). Our invasive study assessed the FF value and variability at the radial and femoral artery levels and evaluated the recommended fixed FF value of 0.33.
METHODS AND RESULTS
Hemodynamically stable patients were prospectively included in 2 intensive care units. FF was documented at baseline and during dynamic maneuvers. A total of 632 patients (64±16 years of age, 66% men, MAP=81±14 mm Hg) were included. Among them, 355 (56%) had a radial catheter and 277 (44%) had a femoral catheter. The FF was 0.34±0.06. In multiple linear regression, FF was influenced by biological sex (<0.0001) and heart rate (=0.04) but not by height, weight, or catheter location. The radial FF was 0.35±0.06, whereas the femoral FF was 0.34±0.05 (=0.08). Both radial and femoral FF were higher in women than in men (<0.05). When using the 0.33 FF value to estimate MAP, the error was -0.4±4.0 mm Hg and -0.1±2.9 mm Hg at the radial and femoral level, respectively, and the MAP estimate still demonstrated high accuracy and good precision even after changes in norepinephrine dose, increase in positive end-expiratory pressure level, fluid administration, or prone positioning (n=218).
CONCLUSIONS
Despite higher FF in women and despite interindividual variability in FF, using a fixed FF value of 0.33 yielded accurate and precise estimations of MAP. This finding has potential implications for blood pressure monitoring devices and the study of pulse wave amplification.
Topics: Male; Humans; Female; Arterial Pressure; Femoral Artery; Heart Rate; Radial Artery; Blood Pressure
PubMed: 38240278
DOI: 10.1161/JAHA.123.031969 -
Journal of Thermal Biology Dec 2023Passive heating is receiving increasing attention within human performance and health contexts. A low-cost, portable steam sauna pod may offer an additional tool for...
INTRODUCTION
Passive heating is receiving increasing attention within human performance and health contexts. A low-cost, portable steam sauna pod may offer an additional tool for those seeking to manipulate physiological (cardiovascular, thermoregulatory and sudomotor) and perceptual responses for improving sporting or health profiles. This study aimed to 1) report the different levels of heat stress and determine the pods' inter-unit reliability, and 2) quantify the reliability of physiological and perceptual responses to passive heating.
METHOD
In part 1, five pods were assessed for temperature and relative humidity (RH) every 5 min across 70 min of heating for each of the 9 settings. In part 2, twelve males (age: 24 ± 4 years) completed two 60 min trials of passive heating (3 × 20 min at 44 °C/99% RH, separated by 1 week). Heart rate (HR), rectal (T) and tympanic temperature (T) were recorded every 5 min, thermal comfort (T) and sensation (T) every 10 min, mean arterial pressure (MAP) at each break period and sweat rate (SR) after exiting the pod.
RESULTS
In part 1, setting 9 provided the highest temperature (44.3 ± 0.2 °C) and longest time RH remained stable at 99% (51±7 min). Inter-unit reliability data demonstrated agreement between pods for settings 5-9 (intra-class correlation [ICC] >0.9), but not for settings 1-4 (ICC <0.9). In part 2, between-visits, high correlations, and low typical error of measurement (TEM) and coefficient of variation (CV) were found for T, HR, MAP, SR, and T, but not for T or T. A peak T of 38.09 ± 0.30 °C, HR of 124 ± 15 b min and a sweat loss of 0.73 ± 0.33 L were reported. No between-visit differences (p > 0.05) were observed for T, T, T or T, however HR (+3 b.min) and MAP (+4 mmHg) were greater in visit 1 vs. 2 (p < 0.05).
CONCLUSION
Portable steam sauna pods generate reliable heat stress between-units. The highest setting (44 °C/99% RH) also provides reliable but modest adjustments in physiological and perceptual responses.
Topics: Male; Humans; Young Adult; Adult; Steam; Steam Bath; Reproducibility of Results; Heating; Body Temperature Regulation; Hot Temperature; Heart Rate
PubMed: 37979477
DOI: 10.1016/j.jtherbio.2023.103743 -
PloS One 2024Studies indicate that the rated perceived exertion (RPE) during physical exercise can be lower in field environments than indoors. The environmental conditions of those...
PURPOSE
Studies indicate that the rated perceived exertion (RPE) during physical exercise can be lower in field environments than indoors. The environmental conditions of those studies are explored. Furthermore, we study if the same phenomenon is valid when cycling indoors versus in cycle commuting environments with high levels of stimuli from both traffic and suburban-urban elements.
METHODS
Twenty commuter cyclists underwent measurements of heart rate (HR) and oxygen uptake ([Formula: see text]O2) and RPE assessments for breathing and legs, respectively, while cycling in both laboratory and field conditions. A validated mobile metabolic system was used in the field to measure [Formula: see text]O2. Three submaximal cycle ergometer workloads in the laboratory were used to establish linear regression equations between RPE and % of HR reserve (%HRR) and %[Formula: see text]O2max, separately. Based on these equations, RPE from the laboratory was predicted and compared with RPE levels at the participants' individual cycle commutes at equal intensities. The same approach was used to predict field intensities and for comparisons with corresponding measured intensities at equal RPE levels.
RESULTS
The predicted RPE levels based on the laboratory cycling were significantly higher than the RPE levels in cycle commuting at equal intensities (67% of HRR; 65% of [Formula: see text]O2max). For breathing, the mean RPE levels were; 14.0-14.2 in the laboratory and 12.6 in the field. The corresponding levels for legs were; 14.0-14.2 and 11.5. The range of predicted field intensities in terms of %HRR and %[Formula: see text]O2max was 46-56%, which corresponded to median differences of 19-30% compared to the measured intensities in field at equal RPE.
CONCLUSION
The cycle commuters perceived a lower exertion during their cycle commutes compared to ergometer cycling in a laboratory at equal exercise intensities. This may be due to a higher degree of external stimuli in field, although influences from other possible causes cannot be ruled out.
Topics: Humans; Physical Exertion; Adult; Male; Oxygen Consumption; Heart Rate; Bicycling; Perception; Exercise; Female; Exercise Test; Young Adult
PubMed: 38809815
DOI: 10.1371/journal.pone.0300776 -
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 -
ELife Jun 2024Although it is generally held that gastrointestinal (GI) signals are related to emotions, direct evidence for such a link is currently lacking. One of the reasons why...
Although it is generally held that gastrointestinal (GI) signals are related to emotions, direct evidence for such a link is currently lacking. One of the reasons why the internal milieu of the GI system is poorly investigated is because visceral organs are difficult to access and monitor. To directly measure the influence of endoluminal markers of GI activity on the emotional experience, we asked a group of healthy male participants to ingest a pill that measured pH, pressure, and temperature of their GI tract while they watched video clips that consistently induced disgust, fear, happiness, sadness, or a control neutral state. In addition to the objective physiological markers of GI activity, subjective ratings of perceived emotions and visceral (i.e. gastric, respiratory and cardiac) sensations were recorded, as well as changes in heart rate (HR), heart rate variability (HRV) and spontaneous eyes blinks as non-gastric behavioral and autonomic markers of the emotional experience. We found that when participants observed fearful and disgusting video clips, they reported to perceive not only cardiac and respiratory sensations but also gastric sensations, such as nausea. Moreover, we found that there was a clear relation between the physiology of the stomach and the perceived emotions. Specifically, when disgusting video clips were displayed, the more acidic the pH, the more participants reported feelings of disgust and fear; the less acidic the pH, the more they reported happiness. Complementing the results found in the deep gastric realm, we found that disgusting stimuli induced a significant increase in HRV compared to the neutral scenarios, and together with fearful video clips a decrease in HR. Our findings suggest that gastric signals contribute to unique emotional states and that ingestible pills may open new avenues for exploring the deep-body physiology of emotions.
Topics: Humans; Male; Emotions; Adult; Young Adult; Heart Rate; Hydrogen-Ion Concentration
PubMed: 38831694
DOI: 10.7554/eLife.85567 -
PloS One 2023Swimming is a genotype-specific trigger in long QT syndrome type 1 (LQT1).
BACKGROUND
Swimming is a genotype-specific trigger in long QT syndrome type 1 (LQT1).
OBJECTIVE
To examine the autonomic response to water activities in children and adolescents with LQT1.
METHODS
In this cross-sectional study, LQT1 patients were age and sex matched to one healthy control subject. Electrocardiograms (ECGs) were recorded during face immersion (FI), swimming, diving, and whole-body submersion (WBS). Heart rate (HR) and heart rate variability (HRV) was measured. The high frequency (HF) component of HRV was interpreted to reflect parasympathetic activity, while the low frequency (LF) component was interpreted as reflecting the combined influence of sympathetic and parasympathetic activity on autonomic nervous modulation of the heart.
RESULTS
Fifteen LQT1 patients (aged 7-19 years, all on beta-blocker therapy) and fifteen age and sex matched non-medicated controls were included. No significant ventricular arrhythmias were observed in the LQT1 population during the water activities. Out of these 15 matched pairs, 12 pairs managed to complete FI and WBS for more than 10 seconds and were subsequently included in HR and HRV analyses. In response to FI, the LQT1 group experienced a drop in HR of 48 bpm, compared to 67 bpm in the control group (p = 0.006). In response to WBS, HR decreased by 48 bpm in the LQT1 group and 70 bpm in the control group (p = 0.007). A significantly lower PTOT (p < 0.001) and HF (p = 0.011) component was observed before, during and after FI in LQT1 patients compared with the controls. Before, during and after WBS, a significantly lower total power (p < 0.001), LF (p = 0.002) and HF (p = 0.006) component was observed in the LQT1 patients.
CONCLUSION
A significantly lower HR decrease in response to water activities was observed in LQT1 subjects on beta-blocker therapy, compared to matched non-medicated controls. The data suggests an impaired parasympathetic response in LQT1 children and adolescents. An aberrant autonomic nervous system (ANS) response may cause an autonomic imbalance in this patient group.
Topics: Adolescent; Child; Humans; Romano-Ward Syndrome; Cross-Sectional Studies; Heart; Autonomic Nervous System; Electrocardiography; Heart Rate; Long QT Syndrome
PubMed: 38060596
DOI: 10.1371/journal.pone.0295431