-
Biomedical Physics & Engineering Express Sep 2023The combination of magnetic resonance (MR) imaging and linear accelerators (linacs) into MR-Linacs enables continuous MR imaging and advanced gated treatments of...
The combination of magnetic resonance (MR) imaging and linear accelerators (linacs) into MR-Linacs enables continuous MR imaging and advanced gated treatments of patients. Previously, a dose-rate transient (∼8% reduced dose rate during the initial 0.5 s of each beam) was identified for a Viewray MRIdian MR-Linac (Klavsen2022106759). Here, the dose-rate transient is studied in more detail at four linacs of the same type at different hospitals. The implications of dose-rate transients were examined for gated treatments. The dose-rate transients were investigated using dose-per pulse measurements with organic plastic scintillators in three experiments: (i) A gated treatment with the scintillator placed in a moving target in a dynamic phantom, (ii) a gated treatment with the same dynamic conditions but with the scintillator placed in a stationary target, and (iii) measurements in a water-equivalent material to examine beam quality deviations at a dose-per-pulse basis. Gated treatments (i) compared with non-gated treatments with a static target in the same setup showed a broadening of accumulated dose profiles due to motion (dose smearing). The linac with the largest dose-rate transient had a reduced accumulated dose of up to (3.1 ± 0.65) % in the center of the PTV due to the combined dose smearing and dose-rate transient effect. Dose-rate transients were found to vary between different machines. Two MR-Linacs showed initial dose-rate transients that could not be identified from conventional linearity tests. The source of the transients includes an initial change in photon fluence rate and an initial change in x-ray beam quality. For gated treatments, this caused a reduction of more than 1% dose delivered at the central part of the beam for the studied, cyclic-motion treatment plan. Quality assurance of this effect should be considered when gated treatment with the Viewray MRIdian is implemented clinically.
Topics: Humans; Heart Rate; Motion; Phantoms, Imaging; Photons; Plastics
PubMed: 37591227
DOI: 10.1088/2057-1976/acf138 -
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 -
Physiological Measurement Feb 2024. To develop analytical formulas which can serve as quantitative guidelines for the selection of the sampling rate for the electrocardiogram (ECG) required to calculate...
. To develop analytical formulas which can serve as quantitative guidelines for the selection of the sampling rate for the electrocardiogram (ECG) required to calculate heart rate (HR) and heart rate variability (HRV) with a desired level of accuracy.. We developed analytical formulas which relate the ECG sampling rate to conservative bounds on HR and HRV errors: (i) one relating HR and sampling rate to a HR error bound and (ii) the others relating sampling rate to HRV error bounds (in terms of root-mean-square of successive differences (RMSSD) and standard deviation of normal sinus beats (SDNN)). We validated the formulas using experimental data collected from 58 young healthy volunteers which encompass a wide HR and HRV ranges through strenuous exercise.. The results strongly supported the validity of the analytical formulas as well as their tightness. The formulas can be used to (i) predict an upper bound of inaccuracy in HR and HRV for a given sampling rate in conjunction with HR and HRV as well as to (ii) determine a sampling rate to achieve a desired accuracy requirement at a given HR or HRV (or its range).. HR and its variability (HRV) derived from the ECG have been widely utilized in a wide range of research in physiology and psychophysiology. However, there is no established guideline for the selection of the sampling rate for the ECG required to calculate HR and HRV with a desired level of accuracy. Hence, the analytical formulas may guide in selecting sampling rates for the ECG tailored to various applications of HR and HRV.
Topics: Humans; Heart Rate; Electrocardiography; Exercise
PubMed: 38306663
DOI: 10.1088/1361-6579/ad252d -
International Journal of... May 2024Previous studies have shown that the human capacity to gauge one's own physiological state is notoriously flawed. The cause for the mismatch between perceived and...
Previous studies have shown that the human capacity to gauge one's own physiological state is notoriously flawed. The cause for the mismatch between perceived and physiological stress has not yet been properly identified. In this study, we assumed that cardioceptive accuracy (CAc) is positively associated with cardiovascular reactivity, and CAc and expectation about stress might account for the discrepancy between perceived and physiological stress. In a crossover experiment, we assessed cardioceptive accuracy in two ways (mental heartbeat tracking task and perception of heart rate), and induced physiological (handgrip exercise) and mental (N-back task) stress in 64 university students (51 % male, mean age 22.2). We assessed cardiac and electrodermal activity, and expected and perceived stress. We found that indicators of cardioceptive accuracy were not associated with cardiovascular reactivity. However, heart rate perception moderated the association between the change in heart rate and perceived stress in the physical but not in the mental task. Whereas heartbeat tracking accuracy was not associated with perceived stress. Moreover, perceived stress was predicted by the expected stress but not by the change in heart rate and electrodermal activity in the mental stress task. In conclusion, heart rate perception and expectation of stress may shape perceived stress more than actual physiological changes in moderate acute stress.
Topics: Humans; Male; Young Adult; Adult; Female; Heart Rate; Hand Strength; Motivation; Perception; Stress, Psychological; Interoception
PubMed: 38460676
DOI: 10.1016/j.ijpsycho.2024.112326 -
Journal of Cardiac Failure Jun 2024
Topics: Humans; Heart Failure; Stroke Volume; Heart Rate
PubMed: 38447636
DOI: 10.1016/j.cardfail.2024.02.008 -
Sensors (Basel, Switzerland) Feb 2024In the rapidly evolving landscape of continuous electrocardiogram (ECG) monitoring systems, there is a heightened demand for non-invasive sensors capable of measuring... (Review)
Review
In the rapidly evolving landscape of continuous electrocardiogram (ECG) monitoring systems, there is a heightened demand for non-invasive sensors capable of measuring ECGs and detecting heart rate variability (HRV) in diverse populations, ranging from cardiovascular patients to sports enthusiasts. Challenges like device accuracy, patient privacy, signal noise, and long-term safety impede the use of wearable devices in clinical practice. This scoping review aims to assess the performance and safety of novel multi-channel, sensor-based biopotential wearable devices in adults. A comprehensive search strategy was employed on four databases, resulting in 143 records and the inclusion of 12 relevant studies. Most studies focused on healthy adult subjects ( = 6), with some examining controlled groups with atrial fibrillation (AF) ( = 3), long QT syndrome ( = 1), and sleep apnea ( = 1). The investigated bio-sensor devices included chest-worn belts ( = 2), wrist bands ( = 2), adhesive chest strips ( = 2), and wearable textile smart clothes ( = 4). The primary objective of the included studies was to evaluate device performance in terms of accuracy, signal quality, comparability, and visual assessment of ECGs. Safety findings, reported in five articles, indicated no major side effects for long-term/continuous monitoring, with only minor instances of skin irritation. Looking forward, there are ample opportunities to enhance and test these technologies across various physical activity intensities and clinical conditions.
Topics: Adult; Humans; Wearable Electronic Devices; Electrocardiography; Heart Rate; Monitoring, Physiologic; Atrial Fibrillation
PubMed: 38400474
DOI: 10.3390/s24041318 -
Biomedizinische Technik. Biomedical... Jun 2024Monitoring of cardiopulmonary signals plays an important role in many clinical applications. A portable magnetic induction cardiopulmonary signal monitoring system with...
Monitoring of cardiopulmonary signals plays an important role in many clinical applications. A portable magnetic induction cardiopulmonary signal monitoring system with the flexible sensor of double micro-coils is presented in this paper. The detection of cardiopulmonary signals is realized with double micro-coils. The proposed system is safe, non-invasive, simple, and portable compared with traditional direct contact methods. The Hilbert-Huang transform (HHT) based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) is applied to cardiopulmonary signal processing, decomposing cardiopulmonary signal effectively. The sensor to monitor respiration rate and heart rate is validated and demonstrated with healthy volunteers. The root mean squared errors (RMSE) of heart rate, respiration rate under deep breathing and normal breathing are 3.8 beats/min, 0.61 times/min, and 0.98 times/min respectively. The flexible sensor of double micro-coils has little influence on the measurement results at the bending curvature of 33.9 m. Therefore, a suggested solution for monitoring and decomposition of cardiopulmonary signals is easy-to-use, and quick, which can be applied as a respected analytical device on mobile occasions in this study.
Topics: Heart Rate; Respiratory Rate; Humans; Monitoring, Physiologic; Signal Processing, Computer-Assisted; Algorithms
PubMed: 37965772
DOI: 10.1515/bmt-2023-0020 -
Zhonghua Jie He He Hu Xi Za Zhi =... Jul 2023To investigate the relationship between respiratory event-related arousal and increased pulse rate in patients with obstructive sleep apnea (OSA), and to evaluate...
To investigate the relationship between respiratory event-related arousal and increased pulse rate in patients with obstructive sleep apnea (OSA), and to evaluate whether elevated pulse rate can be used as a surrogate marker of arousal. A total of 80 patients [40 males and 40 females, age range (18-63 years), mean age (37±13) years] who attended the Sleep Center of the Department of Respiratory and Critical Care Medicine, Tianjin Medical University General Hospital for polysomnography (PSG) from January 2021 to August 2022 were enrolled. Stable PSG recordings of non-rapid eye movement (NREM) sleep to compare the mean pulse rate (PR), the lowest PR 10 seconds before the onset of arousal, and the highest PR within 10 seconds after the end of arousal associated with each respiratory event. At the same time, the correlation between the arousal index and the pulse rate increase index (PRRI), as well as ΔPR (highest PR-lowest PR) and ΔPR (highest PR-mean PR), respectively, with the duration of respiratory events, the duration of arousal, the magnitude of pulse oximetry (SpO) decline, and the lowest SpO was analyzed. Among the 53 patients, 10 events without arousal and 10 events with arousal (matched for the magnitude of SpO decline) were selected for NREM in each of the 53 patients, and ΔPR before and after termination of respiratory events in the two groups was compared. In addition, 50 patients were simultaneously subjected to portable sleep monitoring (PM) and divided into non-severe OSA group (=22) and severe OSA group (=28), and ΔPR≥3 times,≥6 times,≥9 times, and≥12 times after respiratory events were used as surrogate markers of arousal, and ΔPR was scored manually and integrated into the respiratory event index (REI) of PM. Then, we compared the agreement between REI calculated from the four PR cut-off points and the apnea-hypopnea index (AHI) calculated by the gold standard PSG. ΔPR [(13±7)times/min] and ΔPR [(11±6)times/min] were significantly higher in patients with severe OSA than in patients with non-OSA,mild and moderate OSA. The arousal index was positively correlated with the four PRRIs ( 0.968, 0.886, 0.773, 0.687, <0.001, respectively), and the highest PR [(77±12) times/min] within 10 s after the end of arousal was significantly higher than the lowest PR [(65±10) times/min, =113.24, <0.001] and the mean PR [(67±11) times/min, =103.02, <0.001]. ΔPR and ΔPR were moderately correlated with the decrease in SpO (=0.490, 0.469, <0.001). After matching the magnitude of SpO decline, the ΔPR[(9±6)/min] before and after the termination of respiratory events with arousal was significantly higher than that of respiratory events without arousal [(6±5)/min, =7.72, <0.001]. The differences between REI+PRRI and REI+PRRI and AHI in the non-severe OSA group were not statistically significant ( values 0.055 and 0.442, respectively), and REI+PRRI and AHI showed good agreement (the mean difference was 0.7 times/h, 95% 8.3-7.0 times/h). The four indicators of PM in the severe OSA group were statistically different from AHI (all <0.05), and the agreement was poor. Respiratory event-related arousal in OSA patients is independently associated with increased PR, and frequent arousal may lead to increased frequency of PR fluctuations, and elevated PR may be used as a surrogate marker of arousal, especially in patients with non-severe OSA, where elevated PR≥6 times significantly improves the diagnostic agreement between PM and PSG.
Topics: Male; Female; Humans; Adolescent; Young Adult; Adult; Middle Aged; Heart Rate; Sleep Apnea, Obstructive; Sleep; Arousal; Biomarkers
PubMed: 37402658
DOI: 10.3760/cma.j.cn112147-20221102-00867 -
Sensors (Basel, Switzerland) Jul 2023Instantaneous heart rate (IHR) has been investigated for sleep applications, such as sleep apnea detection and sleep staging. To ensure the comfort of the patient during...
Instantaneous heart rate (IHR) has been investigated for sleep applications, such as sleep apnea detection and sleep staging. To ensure the comfort of the patient during sleep, it is desirable for IHR to be measured in a contact-free fashion. In this work, we use speckle vibrometry (SV) to perform on-skin and on-textile IHR monitoring in a sleep setting. Minute motions on the laser-illuminated surface can be captured by a defocused camera, enabling the detection of cardiac motions even on textiles. We investigate supine, lateral, and prone sleeping positions. Based on Bland-Altman analysis between SV cardiac measurements and electrocardiogram (ECG), with respect to each position, we achieve the best limits of agreement with ECG values of [-8.65, 7.79] bpm, [-9.79, 9.25] bpm, and [-10.81, 10.23] bpm, respectively. The results indicate the potential of using speckle vibrometry as a contact-free monitoring method for instantaneous heart rate in a setting where the participant is allowed to rest in a spontaneous position while covered by textile layers.
Topics: Humans; Heart Rate Determination; Monitoring, Physiologic; Heart Rate; Electrocardiography; Sleep
PubMed: 37514607
DOI: 10.3390/s23146312 -
Indian Journal of Pediatrics Nov 2023To evaluate the ability of the Nemocare Raksha (NR), an internet of things (IoT)-enabled device, to continuously monitor vitals for 6 h and its safety in newborns. The...
OBJECTIVES
To evaluate the ability of the Nemocare Raksha (NR), an internet of things (IoT)-enabled device, to continuously monitor vitals for 6 h and its safety in newborns. The accuracy of the device was also compared with the readings from the standard device used in the pediatric ward.
METHOD
Forty neonates (either gender) weighing ≥ 1.5 kg were included in the study. Heart rate, respiratory rate, body temperature, and oxygen saturation was measured using the NR and compared with standard care devices. Safety was assessed by monitoring for skin changes and local rise in temperature. The neonatal infant pain scale (NIPS) was used to assess pain and discomfort.
RESULT
A total of 227 h of observations (5.67 h per baby) were obtained. No discomfort or device-related adverse events were noted during the study period. The mean difference between the NR and the standard monitoring was 0.66 (0.42 to 0.90) for temperature (°C); -6.57 (-8.66 to -4.47) for heart rate (bpm); 7.60 (6.52 to 8.68) for respiratory rate (breaths per minute); -0.79 (-1.10 to -0.48) for oxygen saturation (%). The level of agreement analyzed using the intraclass correlation coefficient (ICC) was good for heart rate [ICC 0.77 (0.72 to 0.82); p value < 0.001] and oxygen saturation [ICC 0.80 (0.75 to 0.84); p value < 0.001]; moderate for body temperature [ICC 0.54 (0.36 to 0.60); p value < 0.001] and poor for respiratory rate [ICC 0.30 (0.10 to 0.44); p value 0.002].
CONCLUSION
The NR was able to seamlessly monitor vital parameters in neonates without any safety concern. The device showed a good level of agreement for heart rate and oxygen saturation among the four parameters measured.
Topics: Infant; Humans; Infant, Newborn; Child; Respiratory Rate; Heart Rate; Hospitals; Pain; Monitoring, Physiologic
PubMed: 36809506
DOI: 10.1007/s12098-022-04459-8