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Medical & Biological Engineering &... Oct 2023Remote photoplethysmography (rPPG) enables contact-free monitoring of the pulse rate by using a color camera. The fundamental limitation is that motion artifacts and...
Remote photoplethysmography (rPPG) enables contact-free monitoring of the pulse rate by using a color camera. The fundamental limitation is that motion artifacts and changes in ambient light conditions greatly affect the accuracy of pulse-rate monitoring. We propose use of a high-speed camera and a motion suppression algorithm with high computational efficiency. This system incorporates a number of major improvements including reproduction of pulse wave details, high-precision pulse-rate monitoring of moving subjects, and excellent scene scalability. A series of quantization methods were used to evaluate the effect of different frame rates and different algorithms in pulse-rate monitoring of moving subjects. The experimental results show that use of 180-fps video and a Plane-Orthogonal-to-Skin (POS) algorithm can produce high-precision pulse-rate monitoring results with mean absolute error can be less than 5 bpm and the relative accuracy reaching 94.5%. Thus, it has significant potential to improve personal health care and intelligent health monitoring.
Topics: Humans; Heart Rate; Pulse; Skin; Photoplethysmography; Motion; Algorithms; Signal Processing, Computer-Assisted
PubMed: 37474842
DOI: 10.1007/s11517-023-02884-1 -
The Journal of the Acoustical Society... Jun 2023Users of cochlear implants (CIs) struggle in situations that require selective hearing to focus on a target source while ignoring other sources. One major reason for...
Users of cochlear implants (CIs) struggle in situations that require selective hearing to focus on a target source while ignoring other sources. One major reason for that is the limited access to timing cues such as temporal pitch or interaural time differences (ITDs). Various approaches to improve timing-cue sensitivity while maintaining speech understanding have been proposed, among them inserting extra pulses with short inter-pulse intervals (SIPIs) into amplitude-modulated (AM) high-rate pulse trains. Indeed, SIPI rates matching the naturally occurring AM rates improve pitch discrimination. For ITD, however, low SIPI rates are required, potentially mismatching the naturally occurring AM rates and thus creating unknown pitch effects. In this study, we investigated the perceptual contribution of AM and SIPI rate to pitch discrimination in five CI listeners and with two AM depths (0.1 and 0.5). Our results show that the SIPI-rate cue generally dominated the percept for both consistent and inconsistent cues. When tested with inconsistent cues, also the AM rate contributed, however, at the large AM depth only. These findings have implications when aiming at jointly improving temporal-pitch and ITD sensitivity in a future mixed-rate stimulation approach.
Topics: Cues; Heart Rate; Pitch Discrimination; Hearing; Cochlear Implantation
PubMed: 37307025
DOI: 10.1121/10.0019452 -
Methods (San Diego, Calif.) Oct 2023Heart rate variability (HRV) is an important indicator of autonomic nervous system activity and can be used for the identification of affective states. The development...
Heart rate variability (HRV) is an important indicator of autonomic nervous system activity and can be used for the identification of affective states. The development of remote Photoplethysmography (rPPG) technology has made it possible to measure pulse rate variability (PRV) using a camera without any sensor-skin contact, which is highly correlated to HRV, thus, enabling contactless assessment of emotional states. In this study, we employed ten machine learning techniques to identify emotions using camera-based PRV features. Our experimental results show that the best classification model achieved a coordination correlation coefficient of 0.34 for value recognition and 0.36 for arousal recognition. The rPPG-based measurement has demonstrated promising results in detecting HAHV (high-arousal high-valence) emotions with high accuracy. Furthermore, for emotions with less noticeable variations, such as sadness, the rPPG-based measure outperformed the baseline deep network for facial expression analysis.
Topics: Heart Rate; Emotions; Machine Learning; Skin
PubMed: 37678514
DOI: 10.1016/j.ymeth.2023.08.014 -
Sensors (Basel, Switzerland) Jan 2023Despite the notable recent developments in the field of remote photoplethysmography (rPPG), extracting a reliable pulse rate variability (PRV) signal still remains a...
Despite the notable recent developments in the field of remote photoplethysmography (rPPG), extracting a reliable pulse rate variability (PRV) signal still remains a challenge. In this study, eight image-based photoplethysmography (iPPG) extraction methods (GRD, AGRD, PCA, ICA, LE, SPE, CHROM, and POS) were compared in terms of pulse rate (PR) and PRV features. The algorithms were made robust for motion and illumination artifacts by using ad hoc pre- and postprocessing steps. Then, they were systematically tested on the public dataset UBFC-RPPG, containing data from 42 subjects sitting in front of a webcam (30 fps) while playing a time-sensitive mathematical game. The performances of the algorithms were evaluated by statistically comparing iPPG-based and finger-PPG-based PR and PRV features in terms of Spearman's correlation coefficient, normalized root mean square error (NRMSE), and Bland-Altman analysis. The study revealed POS and CHROM techniques to be the most robust for PR estimation and the assessment of overall autonomic nervous system (ANS) dynamics by using PRV features in time and frequency domains. Furthermore, we demonstrated that a reliable characterization of the vagal tone is made possible by computing the Poincaré map of PRV series derived from the POS and CHROM methods. This study supports the use of iPPG systems as promising tools to obtain clinically useful and specific information about ANS dynamics.
Topics: Humans; Photoplethysmography; Signal Processing, Computer-Assisted; Heart Rate; Diagnostic Imaging; Algorithms; Wearable Electronic Devices
PubMed: 36772543
DOI: 10.3390/s23031505 -
IEEE Transactions on Bio-medical... May 2020Near-infrared (NIR) remote photoplethysmography (PPG) promises attractive applications in darkness, as it involves unobtrusive, invisible light. However, since the PPG...
Near-infrared (NIR) remote photoplethysmography (PPG) promises attractive applications in darkness, as it involves unobtrusive, invisible light. However, since the PPG strength (AC/DC) is much lower in the NIR spectrum than in the RGB spectrum, robust vital signs monitoring is more challenging. In this paper, we propose a new PPG-extraction method, DIScriminative signature based extraction (DIS), to significantly improve the pulse-rate measurement in NIR. Our core idea is to use both the color signals containing blood absorption variations and additional disturbance signals as input for PPG extraction. By defining a discriminative signature, we use one-step least-squares regression (joint optimization) to retrieve the pulsatile component from color signals and suppress disturbance signals simultaneously. A large-scale lab experiment, recorded in NIR with heavy body motions, shows the significant improvement of DIS over the state-of-the-art method, whereas its principle is simple and generally applicable.
Topics: Heart Rate; Least-Squares Analysis; Photoplethysmography; Signal Processing, Computer-Assisted
PubMed: 31484105
DOI: 10.1109/TBME.2019.2938564 -
Scientific Reports Jan 2023Early recognition of cardiopulmonary arrest (CPA) expedites emergency calls and resuscitation and improves the survival rate of unresponsive individuals. However, the... (Observational Study)
Observational Study
Early recognition of cardiopulmonary arrest (CPA) expedites emergency calls and resuscitation and improves the survival rate of unresponsive individuals. However, the accuracy of breathing and radial artery pulse assessment by non-medical persons is poorly understood. The aim of this study was to determine the accuracy of breathing assessment and radial pulse palpation among 450 non-medical personnel using a high-fidelity simulator. We examined the accuracy of 10 second's assessment for breathing and radial pulse using a high-fidelity mannequin simulator, included 496 non-medical participants (school teachers) between 2016-2018. For a primary results, the sensitivity for the detection of the presence of the breathing and radial pulse was 96.2% (97.5% for sensitivity and 92.0% for specificity) and 91.7% (99.1% for sensitivity and 56.8% for specificity), respectively. Futher, breathing rate and radial pulse rate were strongly correlated with the assessments, with Spearman's correlation coefficients of 0.813 (P < 0.001) and 0.719 (P < 0.001), respectively. In contrast, radial pulse strength was weakly correlated with the assessment (coefficient of 0.288, P < 0.001). Our results suggested that non-medical persons would show high accuracy in detecting and measuring respiration and radial pulse, although they did not accurately determine radial pulse strength for the early recognition of CPA.
Topics: Humans; Cross-Sectional Studies; Respiration; Respiratory Rate; Heart Rate; Radial Artery
PubMed: 36720983
DOI: 10.1038/s41598-023-28408-3 -
European Review For Medical and... Jan 2021Phacoemulsification is the most common cataract surgery that needs optimum circumstances in the field of surgery. This comparative pre- and postoperative study assessed... (Comparative Study)
Comparative Study Observational Study
OBJECTIVE
Phacoemulsification is the most common cataract surgery that needs optimum circumstances in the field of surgery. This comparative pre- and postoperative study assessed the efficacy and safety of using adrenaline in the irrigating solution as an adjunct to preoperative topical mydriatics in dark irides during Phaco surgery.
PATIENTS AND METHODS
This was a prospective observational study that enrolled 421 cataract patients (421 eyes) with dark irides, who were scheduled for Phaco surgery from January 2019 to August 2020. All patients received intraoperative irrigation of a balanced salt solution containing adrenaline. The pulse rate and systolic and diastolic blood pressure of all patients were recorded pre- and postoperatively. In addition, the presence of intraoperative floppy-iris syndrome (IFIS), need for pupil mechanical dilatation, and incidence of posterior capsular rupture were recorded.
RESULTS
The sample consisted of 421 patients (421 eyes) all had dark irides. Pulse rate and systolic and diastolic blood pressure did not significantly increase post-operatively (p <0.001). Mechanical dilatation of the pupil was performed in one patient (0.24%) and seven eyes (1.66%) were found to have IFIS. There was no case of posterior capsule rupture.
CONCLUSIONS
In comparison with the use of preoperative topical mydriatics alone, adding intracameral adrenaline to the irrigation fluid maintains better pupillary dilatation throughout Phacoemulsification surgery, thereby providing better clinical outcomes in dark irides, even in those with IFIS. Its use has no incremental effect on either blood pressure or pulse rate.
Topics: Administration, Topical; Adult; Aged; Blood Pressure; Epinephrine; Eye Color; Female; Heart Rate; Humans; Injections; Intraoperative Complications; Iris; Iris Diseases; Male; Middle Aged; Mydriatics; Phacoemulsification; Prospective Studies; Pupil; Therapeutic Irrigation
PubMed: 34337725
DOI: 10.26355/eurrev_202101_26389 -
Australasian Physical & Engineering... Sep 2017Designing an efficient automatic emotion recognition system based on physiological signals has attracted great interests within the research of human-machine...
Designing an efficient automatic emotion recognition system based on physiological signals has attracted great interests within the research of human-machine interactions. This study was aimed to classify emotional responses by means of a simple dynamic signal processing technique and fusion frameworks. The electrocardiogram and finger pulse activity of 35 participants were recorded during rest condition and when subjects were listening to music intended to stimulate certain emotions. Four emotion categories, including happiness, sadness, peacefulness, and fear were chosen. Estimating heart rate variability (HRV) and pulse rate variability (PRV), 4 Poincare indices in 10 lags were extracted. The support vector machine classifier was used for emotion classification. Both feature level (FL) and decision level (DL) fusion schemes were examined. Significant differences have been observed between lag 1 Poincare plot indices and the other lagged measures. The mean accuracies of 84.1, 82.9, 79.68, and 76.05% were obtained for PRV, DL, FL, and HRV measures, respectively. However, DL outperformed others in discriminating sadness and peacefulness, using SD and total features, correspondingly. In both cases, the classification rates improved up to 92% (with the sensitivity of 95% and specificity of 83.33%). Totally, DL resulted in better performances compared to FL. In addition, the impact of the fusion rules on the classification performances has been confirmed.
Topics: Algorithms; Emotions; Female; Heart Rate; Humans; Male; Pulse; Young Adult
PubMed: 28717902
DOI: 10.1007/s13246-017-0571-1 -
Medical Engineering & Physics Jul 2022Camera-based vital signs monitoring in recent years has attracted more and more researchers and the results are promising. However, a few research works focus on heart...
Camera-based vital signs monitoring in recent years has attracted more and more researchers and the results are promising. However, a few research works focus on heart rate extraction under extremely low illumination environments. In this paper, we propose a novel framework for remote heart rate estimation under low-light conditions. This method uses singular spectrum analysis (SSA) to decompose the filtered signal into several reconstructed components. A spectral masking algorithm is utilized to refine the preliminary candidate components on the basis of a reference heart rate. The contributive components are fused into the final pulse signal. To evaluate the performance of our framework in low-light conditions, the proposed approach is tested on a large-scale multi-illumination HR dataset (named MIHR). The test results verify that the proposed method has stronger robustness to low illumination than state-of-the-art methods, effectively improving the signal-to-noise ratio and heart rate estimation precision. We further perform experiments on the PUlse RatE detection (PURE) dataset which is recorded under normal light conditions to demonstrate the generalization of our method. The experiment results show that our method can stably detect pulse rate and achieve comparative results. The proposed method pioneers a new solution to the remote heart rate estimation in low-light conditions.
Topics: Heart Rate; Photoplethysmography; Signal Processing, Computer-Assisted; Signal-To-Noise Ratio; Spectrum Analysis
PubMed: 35781386
DOI: 10.1016/j.medengphy.2022.103822 -
Biosensors Oct 2016To achieve sensitivity, comfort, and durability in vital sign monitoring, this study explores the use of radar technologies in wearable devices. The study first detected... (Review)
Review
To achieve sensitivity, comfort, and durability in vital sign monitoring, this study explores the use of radar technologies in wearable devices. The study first detected the respiratory rates and heart rates of a subject at a one-meter distance using a self-injection-locked (SIL) radar and a conventional continuous-wave (CW) radar to compare the sensitivity versus power consumption between the two radars. Then, a pulse rate monitor was constructed based on a bistatic SIL radar architecture. This monitor uses an active antenna that is composed of a SIL oscillator (SILO) and a patch antenna. When attached to a band worn on the subject's wrist, the active antenna can monitor the pulse on the subject's wrist by modulating the SILO with the associated Doppler signal. Subsequently, the SILO's output signal is received and demodulated by a remote frequency discriminator to obtain the pulse rate information.
Topics: Heart Rate; Humans; Monitoring, Physiologic; Pulse; Radar; Vital Signs; Wrist
PubMed: 27792176
DOI: 10.3390/bios6040054