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1.
IEEE Trans Biomed Circuits Syst ; 13(6): 1593-1602, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31804943

RESUMO

This paper presents a ballistocardiogram (BCG) based beat-to-beat heart rate (HR) measurement system for healthcare applications in smart home. The BCG signal is picked up by two parallel connected piezoelectric elements, and processed by a robust HR detection algorithm. To deal with the diversity in BCG signal, a personalized heartbeat template is extracted to handle the diversity in BCG signal. The Pearson correlation coefficient is used to correlate between personalized template and the BCG signal. Heartbeats are detected by using the Hilbert Transform. The system is verified on 32 subjects with simultaneously recorded BCG and ECG signals. With the reference to ECG signal, we have achieved mean absolute relative error of the beat-to-beat intervals of 4.56%, and average absolute error ±standard deviation of absolute error for HR estimation in a 30-seconds window of 0.59 ±0.56 beats per minute. Meanwhile, 99.67% of the beat-to-beat intervals are detected on average.


Assuntos
Balistocardiografia/instrumentação , Eletrocardiografia/instrumentação , Coração/fisiologia , Adulto , Algoritmos , Fontes de Energia Elétrica , Feminino , Frequência Cardíaca , Humanos , Masculino , Adulto Jovem
2.
Sensors (Basel) ; 19(9)2019 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-31072036

RESUMO

There exists a technological momentum towards the development of unobtrusive, simple, and reliable systems for long-term sleep monitoring. An off-the-shelf commercial pressure sensor meeting these requirements is the Emfit QS. First, the potential for sleep apnea screening was investigated by revealing clusters of contaminated and clean segments. A relationship between the irregularity of the data and the sleep apnea severity class was observed, which was valuable for screening (sensitivity 0.72, specificity 0.70), although the linear relation was limited ( R 2 of 0.16). Secondly, the study explored the suitability of this commercial sensor to be merged with gold standard polysomnography data for future sleep monitoring. As polysomnography (PSG) and Emfit signals originate from different types of sensor modalities, they cannot be regarded as strictly coupled. Therefore, an automated synchronization procedure based on artefact patterns was developed. Additionally, the optimal position of the Emfit for capturing respiratory and cardiac information similar to the PSG was identified, resulting in a position as close as possible to the thorax. The proposed approach demonstrated the potential for unobtrusive screening of sleep apnea patients at home. Furthermore, the synchronization framework enabled supervised analysis of the commercial Emfit sensor for future sleep monitoring, which can be extended to other multi-modal systems that record movements during sleep.


Assuntos
Balistocardiografia/instrumentação , Programas de Rastreamento , Monitorização Fisiológica/instrumentação , Síndromes da Apneia do Sono/diagnóstico , Síndromes da Apneia do Sono/fisiopatologia , Sono/fisiologia , Algoritmos , Artefatos , Eletrocardiografia , Feminino , Humanos , Modelos Lineares , Masculino , Pessoa de Meia-Idade , Polissonografia , Respiração , Processamento de Sinais Assistido por Computador
3.
Sensors (Basel) ; 19(7)2019 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-30934719

RESUMO

Hypertension is one of the most common cardiovascular diseases, which will cause severe complications if not treated in a timely way. Early and accurate identification of hypertension is essential to prevent the condition from deteriorating further. As a kind of complex physiological state, hypertension is hard to characterize accurately. However, most existing hypertension identification methods usually extract features only from limited aspects such as the time-frequency domain or non-linear domain. It is difficult for them to characterize hypertension patterns comprehensively, which results in limited identification performance. Furthermore, existing methods can only determine whether the subjects suffer from hypertension, but they cannot give additional useful information about the patients' condition. For example, their classification results cannot explain why the subjects are hypertensive, which is not conducive to further analyzing the patient's condition. To this end, this paper proposes a novel hypertension identification method by integrating classification and association rule mining. Its core idea is to exploit the association relationship among multi-dimension features to distinguish hypertensive patients from normotensive subjects. In particular, the proposed method can not only identify hypertension accurately, but also generate a set of class association rules (CARs). The CARs are proved to be able to reflect the subject's physiological status. Experimental results based on a real dataset indicate that the proposed method outperforms two state-of-the-art methods and three common classifiers, and achieves 84.4%, 82.5% and 85.3% in terms of accuracy, precision and recall, respectively.


Assuntos
Leitos , Mineração de Dados/métodos , Hipertensão/patologia , Adulto , Idoso , Algoritmos , Balistocardiografia/instrumentação , Balistocardiografia/métodos , Feminino , Frequência Cardíaca/fisiologia , Humanos , Hipertensão/classificação , Masculino , Sistemas Microeletromecânicos , Pessoa de Meia-Idade , Análise de Ondaletas
4.
IEEE Trans Biomed Eng ; 66(3): 740-748, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30010544

RESUMO

We propose a nonwearable hydraulic bed sensor system that is placed underneath the mattress to estimate the relative systolic blood pressure of a subject, which only differs from the actual blood pressure by a scaling and an offset factor. Two types of features are proposed to obtain the relative blood pressure, one based on the strength and the other on the morphology of the bed sensor ballistocardiogram pulses. The relative blood pressure is related to the actual by a scale and an offset factor that can be obtained through calibration. The proposed system is able to extract the relative blood pressure more accurately with a less sophisticated sensor system compared to those from the literature. We tested the system using a dataset collected from 48 subjects right after active exercises. Comparison with the ground truth obtained from the blood pressure cuff validates the promising performance of the proposed system, where the mean correlation between the estimate and the ground truth is near to 90% for the strength feature and 83% for the morphology feature.


Assuntos
Balistocardiografia/métodos , Leitos , Determinação da Pressão Arterial/métodos , Processamento de Sinais Assistido por Computador , Adolescente , Adulto , Balistocardiografia/instrumentação , Pressão Sanguínea/fisiologia , Determinação da Pressão Arterial/instrumentação , Calibragem , Desenho de Equipamento , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
5.
IEEE J Biomed Health Inform ; 23(2): 618-630, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-29994011

RESUMO

Home monitoring requires measuring the physiological and behavioral signals without impairing a subject's everyday life. This paper presents an integrated and noncontact approach for obtaining simultaneous physiological and behavioral signals of recumbent humans in beds using a home-monitoring application. In the proposed approach, a fabric-sheet unified sensing electrode (FUSE) obtains physiological signals by recording the electrocardiogram (ECG), chest and abdominal respiratory movements (RMs), and ballistocardiogram (BCG). The FUSE also detects the behavioral signals of body proximity (BPx) and lateral/supine lying postures. A prototype system with FUSE was validated in a short-term experiment and 6-h overnight measurements on two different groups composed of seven lying subjects. The results confirmed that the approach senses each signal independently and records the ECG, RMs, BCG, and BPx signals simultaneously. The mean sensitivities of the R and T waves of the ECG during sleep were 86.1% and 88.0%, respectively, whereas those of the chest and abdominal RMs were 90.7% and 90.1%, respectively. Although our prototype system has room for improvement, the results suggest that our approach enables the unconstrained, nocturnal monitoring of the physiological and behavioral signals in recumbent humans. The at-home monitoring of the physiological and behavioral signals is expected to contribute to cost-effective personalized healthcare in the future. This noncontact and easy-to-install system for in-bed measurements can facilitate a new era of home monitoring.


Assuntos
Leitos , Monitorização Fisiológica , Postura/fisiologia , Processamento de Sinais Assistido por Computador , Adulto , Balistocardiografia/instrumentação , Eletrocardiografia/instrumentação , Desenho de Equipamento , Serviços de Assistência Domiciliar , Humanos , Masculino , Pessoa de Meia-Idade , Monitorização Fisiológica/instrumentação , Monitorização Fisiológica/métodos , Movimento/fisiologia , Respiração , Têxteis , Adulto Jovem
6.
Conf Proc IEEE Eng Med Biol Soc ; 2018: 5378-5381, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-30441552

RESUMO

A wearable multi-sensor system allowing synchronized unobtrusive measurements of 4 vital signs at a dedicated location of interest is presented. The 4×U sensor is capable of synchronously measuring magnetic impedance, reflective photoplethysmography, capacitive electrocardiogram and seismocardiography (ballistocardiography). The hardware of all modalities is described and some preliminary results are reported.


Assuntos
Balistocardiografia/instrumentação , Eletrocardiografia/instrumentação , Fotopletismografia/instrumentação , Dispositivos Eletrônicos Vestíveis , Humanos , Sinais Vitais
7.
Sensors (Basel) ; 18(10)2018 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-30322147

RESUMO

Several devices and measurement approaches have recently been developed to perform ballistocardiogram (BCG) and seismocardiogram (SCG) measurements. The development of a wireless acquisition system (hardware and software), incorporating a novel high-resolution micro-electro-mechanical system (MEMS) accelerometer for SCG and BCG signals acquisition and data treatment is presented in this paper. A small accelerometer, with a sensitivity of up to 0.164 µs/µg and a noise density below 6.5 µg/ Hz is presented and used in a wireless acquisition system for BCG and SCG measurement applications. The wireless acquisition system also incorporates electrocardiogram (ECG) signals acquisition, and the developed software enables the real-time acquisition and visualization of SCG and ECG signals (sensor positioned on chest). It then calculates metrics related to cardiac performance as well as the correlation of data from previously performed sessions with echocardiogram (ECHO) parameters. A preliminarily clinical study of over 22 subjects (including healthy subjects and cardiovascular patients) was performed to test the capability of the developed system. Data correlation between this measurement system and echocardiogram exams is also performed. The high resolution of the MEMS accelerometer used provides a better signal for SCG wave recognition, enabling a more consistent study of the diagnostic capability of this technique in clinical analysis.


Assuntos
Balistocardiografia/instrumentação , Doenças Cardiovasculares/diagnóstico , Técnicas de Diagnóstico Cardiovascular/instrumentação , Processamento de Sinais Assistido por Computador , Acelerometria/instrumentação , Adulto , Idoso , Balistocardiografia/métodos , Eletrocardiografia , Desenho de Equipamento , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , Sistemas Microeletromecânicos , Pessoa de Meia-Idade , Razão Sinal-Ruído , Vibração , Tecnologia sem Fio
8.
Sensors (Basel) ; 18(5)2018 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-29738456

RESUMO

This study demonstrates the feasibility of using a seat sensor designed for occupant classification from a production passenger vehicle to measure an occupant’s respiration rate (RR) and heart rate (HR) in a laboratory setting. Relaying occupant vital signs after a crash could improve emergency response by adding a direct measure of the occupant state to an Advanced Automatic Collision Notification (AACN) system. Data was collected from eleven participants with body weights ranging from 42 to 91 kg using a Ford Mustang passenger seat and seat sensor. Using a ballistocardiography (BCG) approach, the data was processed by time domain filtering and frequency domain analysis using the fast Fourier transform to yield RR and HR in a 1-min sliding window. Resting rates over the 30-min data collection and continuous RR and HR signals were compared to laboratory physiological instruments using the Bland-Altman approach. Differences between the seat sensor and reference sensor were within 5 breaths per minute for resting RR and within 15 beats per minute for resting HR. The time series comparisons for RR and HR were promising with the frequency analysis technique outperforming the peak detection technique. However, future work is necessary for more accurate and reliable real-time monitoring of RR and HR outside the laboratory setting.


Assuntos
Balistocardiografia/métodos , Frequência Cardíaca/fisiologia , Taxa Respiratória/fisiologia , Automóveis , Balistocardiografia/instrumentação , Peso Corporal , Feminino , Humanos , Masculino
9.
J Appl Physiol (1985) ; 124(2): 452-461, 2018 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-28798198

RESUMO

Cardiovascular diseases (CVDs) are prevalent in the US, and many forms of CVD primarily affect the mechanical aspects of heart function. Wearable technologies for monitoring the mechanical health of the heart and vasculature could enable proactive management of CVDs through titration of care based on physiological status as well as preventative wellness monitoring to help promote lifestyle choices that reduce the overall risk of developing CVDs. Additionally, such wearable technologies could be used to optimize human performance in austere environments. This review describes our progress in developing wearable ballistocardiogram (BCG)- and seismocardiogram-based systems for monitoring relative changes in cardiac output, contractility, and blood pressure. Our systems use miniature, low-noise accelerometers to measure the movements of the body in response to the heartbeat and novel machine learning algorithms to provide robustness against motion artifacts and sensor misplacement. Moreover, we have mathematically related wearable BCG signals-representing local, cardiogenic movements of a point on the body-to better understood whole body BCG signals, and thereby improved estimation of key health parameters. We validated these systems with experiments in healthy subjects, studies in patients with heart failure, and measurements in austere environments such as water immersion. The systems can be used in future work as a tool for clinicians and physiologists to measure the mechanical aspects of cardiovascular function outside of clinical settings, and to thereby titrate care for patients with CVDs, provide preventative screening, and optimize performance in austere environments by providing real-time in-depth information regarding performance and risk.


Assuntos
Balistocardiografia/instrumentação , Monitorização Fisiológica/instrumentação , Dispositivos Eletrônicos Vestíveis , Acelerometria/instrumentação , Animais , Ensaios Clínicos como Assunto , Insuficiência Cardíaca , Humanos
10.
Am J Hypertens ; 30(9): 876-883, 2017 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-28520843

RESUMO

BACKGROUND: Measurement of arterial stiffness should be more available. Our aim was to show that aortic pulse wave velocity can be reliably measured with a bathroom scale combining the principles of ballistocardiography (BCG) and impedance plethysmography on a single foot. METHOD: The calibration of the bathroom scale was conducted on a group of 106 individuals. The aortic pulse wave velocity was measured with the SphygmoCor in the supine position. Three consecutive measurements were then performed on the Withings scale in the standing position. This aorta-leg pulse transit time (alPTT) was then converted into a velocity with the additional input of the height of the person. Agreement between the SphygmoCor and the bathroom scale so calibrated is assessed on a separate group of 86 individuals, following the same protocol. RESULTS: The bias is 0.25 m·s-1 and the SE 1.39 m·s-1. This agreement with Sphygmocor is "acceptable" according to the ARTERY classification. The alPTT correlated well with cfPTT with (Spearman) R = 0.73 in pooled population (cal 0.79, val 0.66). The aorta-leg pulse wave velocity correlated with carotid-femoral pulse wave velocity with R = 0.76 (cal 0.80, val 0.70). CONCLUSION: Estimation of the aortic pulse wave velocity is feasible with a bathroom scale. Further investigations are needed to improve the repeatability of measurements and to test their accuracy in different populations and conditions.


Assuntos
Antropometria/instrumentação , Balistocardiografia/instrumentação , Peso Corporal , Doenças Cardiovasculares/diagnóstico , Pletismografia de Impedância/instrumentação , Análise de Onda de Pulso/instrumentação , Rigidez Vascular , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Balistocardiografia/normas , Pressão Sanguínea , Estatura , Calibragem , Doenças Cardiovasculares/fisiopatologia , Desenho de Equipamento , Feminino , , Frequência Cardíaca , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Cardiovasculares , Pletismografia de Impedância/normas , Valor Preditivo dos Testes , Análise de Onda de Pulso/normas , Reprodutibilidade dos Testes , Adulto Jovem
11.
Sci Rep ; 6: 31297, 2016 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-27503664

RESUMO

For more than a century, it has been known that the body recoils each time the heart ejects blood into the arteries. These subtle cardiogenic body movements have been measured with increasingly convenient ballistocardiography (BCG) instruments over the years. A typical BCG measurement shows several waves, most notably the "I", "J", and "K" waves. However, the mechanism for the genesis of these waves has remained elusive. We formulated a simple mathematical model of the BCG waveform. We showed that the model could predict the BCG waves as well as physiologic timings and amplitudes of the major waves. The validated model reveals that the principal mechanism for the genesis of the BCG waves is blood pressure gradients in the ascending and descending aorta. This new mechanistic insight may be exploited to allow BCG to realize its potential for unobtrusive monitoring and diagnosis of cardiovascular health and disease.


Assuntos
Balistocardiografia/instrumentação , Sistema Cardiovascular , Monitorização Fisiológica/instrumentação , Idoso , Aorta/fisiologia , Aorta/fisiopatologia , Balistocardiografia/métodos , Pressão Sanguínea , Eletrocardiografia/instrumentação , Eletrocardiografia/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Teóricos , Monitorização Fisiológica/métodos , Movimento , Reprodutibilidade dos Testes , Processamento de Sinais Assistido por Computador
12.
Respiration ; 92(2): 90-7, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27548650

RESUMO

BACKGROUND: Nocturnal hypoxemia, characterized by abnormally low oxygen saturation levels in arterial blood during sleep, is a significant feature of various pathological conditions. The oxygen desaturation index, commonly used to evaluate the nocturnal hypoxemia severity, is acquired using nocturnal pulse oximetry that requires the overnight wear of a pulse oximeter probe. OBJECTIVES: This study aimed to suggest a method for the unconstrained estimation of the oxygen desaturation index. METHODS: We hypothesized that the severity of nocturnal hypoxemia would be positively associated with cardiac sympathetic activation during sleep. Unconstrained heart rate variability monitoring was conducted using three different ballistocardiographic systems to assess cardiac sympathetic activity. Overnight polysomnographic and ballistocardiographic recording pairs were collected from the 20 non-nocturnal hypoxemia (oxygen desaturation index <5 events/h) subjects and the 76 nocturnal hypoxemia patients. Among the 96 recording pairs, 48 were used as training data and the remaining 48 as test data. RESULTS: The regression analysis, performed using the low-frequency component of heart rate variability, exhibited a root mean square error of 3.33 events/h between the estimates and the reference values of the oxygen desaturation index. The nocturnal hypoxemia diagnostic performance produced by our method was presented with an average accuracy of 96.5% at oxygen desaturation index cutoffs of ≥5, 15, and 30 events/h. CONCLUSIONS: Our method has the potential to serve as a complementary measure against the accidental slip-out of a pulse oximeter probe during nocturnal pulse oximetry. The independent application of our method could facilitate home-based long-term oxygen desaturation index monitoring.


Assuntos
Balistocardiografia/instrumentação , Hipóxia/diagnóstico , Oxigênio/sangue , Adulto , Feminino , Humanos , Hipóxia/fisiopatologia , Masculino , Pessoa de Meia-Idade , Polissonografia , Sono
13.
Pacing Clin Electrophysiol ; 39(3): 268-74, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26644068

RESUMO

BACKGROUND: SonR sensor signal correlates well with myocardial contractility expressed in terms of left ventricular (LV) dP/dt max. The aim of our study was to evaluate the changes in myocardial contractility during isometric effort in heart failure patients undergoing cardiac resynchronization therapy (CRT) with right atrial SonR sensor. METHODS: Thirty-one patients (19 men, 65 ± 7 years, LV ejection fraction [LVEF] 28% ± 5%, in sinus rhythm) were implanted with a CRT-defibrillator (CRT-D) device equipped with SonR sensor, which was programmed in VVI mode at 40 beats/min. Twenty-four hours after implantation, each patient underwent a noninvasive hemodynamic evaluation at rest and during isometric effort, including: (1) measurement of beat-to-beat endocavitary SonR signal; (2) echocardiographic assessment; and (3) continuous measurement of blood pressure with Nexfin method (BMEYE, Amsterdam, the Netherlands). The following contractility parameters were considered: (1) mean value of beat-to-beat SonR signal; (2) mean value of LV dP/dt by Nexfin system; and (3) fractional shortening (FS) by echocardiography. RESULTS: At the third minute of the isometric effort, mean value of SonR signal significantly increased from baseline (P < 0.001). Similarly, mean value of both LV dP/dt by Nexfin and FS significantly increased compared to the resting condition (P < 0.001; P < 0.001). While in 27 (88%) patients SonR signal increased at the third minute of the isometric effort, in four (12%) patients SonR signal decreased. In these patients, both LV dP/dt by Nexfin and FS consensually decreased. CONCLUSIONS: In CRT patients, SonR sensor is able to detect changes in myocardial contractility in a consensual way like noninvasive methods such as Nexfin system and echocardiography.


Assuntos
Balistocardiografia/instrumentação , Dispositivos de Terapia de Ressincronização Cardíaca , Insuficiência Cardíaca/prevenção & controle , Insuficiência Cardíaca/fisiopatologia , Sistemas Microeletromecânicos/instrumentação , Contração Miocárdica , Idoso , Terapia de Ressincronização Cardíaca/métodos , Desenho de Equipamento , Análise de Falha de Equipamento , Feminino , Insuficiência Cardíaca/diagnóstico , Humanos , Contração Isométrica , Masculino , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Transdutores
14.
J Acoust Soc Am ; 138(3): EL342-6, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26428837

RESUMO

Ballistocardiography (BCG) measures vibrations of the body caused by ejection of blood from the heart, and the root mean square (RMS) of BCG measured with a weighing scale trends with cardiac output. However, BCG underwater has not been studied. Head-to-foot BCG signals were recorded with an accelerometer on the sternum of three human subjects. The heartbeats were clearly visible in the signals recorded underwater, and the resting change in RMS BCG was +360 µg (+36%) from air to cold water immersion (27.8 °C) while standing. This is within the 32%-62% increase in cardiac output observed in previous head-out immersion studies.


Assuntos
Acústica/instrumentação , Balistocardiografia/instrumentação , Frequência Cardíaca , Imersão , Esterno/fisiologia , Água , Adulto , Débito Cardíaco , Desenho de Equipamento , Humanos , Masculino , Movimento (Física) , Projetos Piloto , Processamento de Sinais Assistido por Computador , Som , Fatores de Tempo , Vibração , Adulto Jovem
15.
Biomed Eng Online ; 14: 16, 2015 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-25884476

RESUMO

BACKGROUND: Seismocardiography is the noninvasive measurement of cardiac vibrations transmitted to the chest wall by the heart during its movement. While most applications for seismocardiography are based on unidirectional acceleration measurement, several studies have highlighted the importance of three-dimensional measurements in cardiac vibration studies. One of the main challenges in using three-dimensional measurements in seismocardiography is the significant inter-subject variability of waveforms. This study investigates the feasibility of using a unified frame of reference to improve the inter-subject variability of seismocardiographic waveforms. METHODS: Three-dimensional seismocardiography signals were acquired from ten healthy subjects to test the feasibility of the present method for improving inter-subject variability of three-dimensional seismocardiograms. The first frame of reference candidate was the orientation of the line connecting the points representing mitral valve closure and aortic valve opening in seismocardiograms. The second candidate was the orientation of the line connecting the two most distant points in the three dimensional seismocardiogram. The unification of the frame of reference was performed by rotating each subject's three-dimensional seismocardiograms so that the lines connecting the desired features were parallel between subjects. RESULTS: The morphology of the three-dimensional seismocardiograms varied strongly from subject to subject. Fixing the frame of reference to the line connecting the MC and AO peaks enhanced the correlation between the subjects in the y axis from 0.42 ± 0.30 to 0.83 ± 0.14. The mean correlation calculated from all axes increased from 0.56 ± 0.26 to 0.71 ± 0.24 using the line connecting the mitral valve closure and aortic valve opening as the frame of reference. When the line connecting the two most distant points was used as a frame of reference, the correlation improved to 0.60 ± 0.22. CONCLUSIONS: The results indicate that using a unified frame of reference is a promising method for improving the inter-subject variability of three-dimensional seismocardiograms. Also, it is observed that three-dimensional seismocardiograms seem to have latent inter-subject similarities, which are feasible to be revealed. Because the projections of the cardiac vibrations on the measurement axes differ significantly, it seems obligatory to use three-dimensional measurements when seismocardiogram analysis is based on waveform morphology.


Assuntos
Acelerometria/métodos , Balistocardiografia/métodos , Individualidade , Contração Miocárdica , Processamento de Sinais Assistido por Computador , Acelerometria/instrumentação , Adulto , Valva Aórtica/fisiologia , Balistocardiografia/instrumentação , Eletrocardiografia , Estudos de Viabilidade , Humanos , Imageamento Tridimensional , Masculino , Valva Mitral/fisiologia , Respiração , Rotação , Esterno/fisiologia , Parede Torácica/fisiologia , Vibração
16.
Sensors (Basel) ; 15(4): 7742-53, 2015 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-25831088

RESUMO

Respiratory and heart failure are conditions that can occur with little warning and may also be difficult to predict. Therefore continuous monitoring of these bio-signals is advantageous for ensuring human health. The car safety belt is mainly designed to secure the occupants of the vehicle in the event of an accident. In the current research a prototype safety belt is developed, which is used to acquire respiratory and heart signals, under laboratory conditions. The current safety belt is constructed using a copper ink based nonwoven material, which works based on the piezo-resistive effect due to the pressure exerted on the sensor as a result of expansion of the thorax/abdomen area of the body for respiration and due to the principle of ballistocardiography (BCG) in heart signal sensing. In this research, the development of a theoretical model to qualitatively describe the piezo-resistive material is also presented in order to predict the relative change in the resistance of the piezo-resistive material due to the pressure applied.


Assuntos
Balistocardiografia/instrumentação , Técnicas Biossensoriais/instrumentação , Cintos de Segurança , Automóveis , Humanos , Modelos Teóricos
17.
IEEE J Biomed Health Inform ; 19(1): 227-35, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25561445

RESUMO

The aim of this paper is to present and evaluate algorithms for heartbeat interval estimation from multiple spatially distributed force sensors integrated into a bed. Moreover, the benefit of using multichannel systems as opposed to a single sensor is investigated. While it might seem intuitive that multiple channels are superior to a single channel, the main challenge lies in finding suitable methods to actually leverage this potential. To this end, two algorithms for heart rate estimation from multichannel vibration signals are presented and compared against a single-channel sensing solution. The first method operates by analyzing the cepstrum computed from the average spectra of the individual channels, while the second method applies Bayesian fusion to three interval estimators, such as the autocorrelation, which are applied to each channel. This evaluation is based on 28 night-long sleep lab recordings during which an eight-channel polyvinylidene fluoride-based sensor array was used to acquire cardiac vibration signals. The recruited patients suffered from different sleep disorders of varying severity. From the sensor array data, a virtual single-channel signal was also derived for comparison by averaging the channels. The single-channel results achieved a beat-to-beat interval error of 2.2% with a coverage (i.e., percentage of the recording which could be analyzed) of 68.7%. In comparison, the best multichannel results attained a mean error and coverage of 1.0% and 81.0%, respectively. These results present statistically significant improvements of both metrics over the single-channel results (p < 0.05).


Assuntos
Algoritmos , Balistocardiografia/métodos , Diagnóstico por Computador/métodos , Frequência Cardíaca/fisiologia , Processamento de Sinais Assistido por Computador , Transdutores de Pressão , Idoso , Balistocardiografia/instrumentação , Leitos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Polissonografia/instrumentação , Polissonografia/métodos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
18.
Conf Proc IEEE Eng Med Biol Soc ; 2015: 7175-9, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26737947

RESUMO

We propose a simple and robust method to detect heartbeats using the ballistocardiogram (BCG) signal that is produced by a hydraulic bed sensor placed under the mattress. The proposed method is found beneficial especially when the BCG signal does not display consistent J-peaks, which can often be the case for overnight, in-home monitoring, especially with frail seniors. Heartbeat detection is based on the short-time energy of the BCG signal. Compared with previous methods that rely on the J-peaks observed from the BCG amplitude, we are able to achieve considerable improvement even when significant distortions are present. Test results are included for different BCG waveform patterns from older adults.


Assuntos
Balistocardiografia/instrumentação , Balistocardiografia/métodos , Frequência Cardíaca/fisiologia , Adolescente , Adulto , Idoso de 80 Anos ou mais , Algoritmos , Leitos , Feminino , Humanos , Masculino
19.
Conf Proc IEEE Eng Med Biol Soc ; 2015: 1833-6, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26736637

RESUMO

Systolic time intervals (STI) are non-invasive measures of cardiac function. Due to the fact that STI can be measured noninvasively outside the clinic, STI are a promising method for long-term monitoring of patients with cardiovascular disease. In particular, the pre-ejection period (PEP) has been measured successfully from body vibrations of the beating heart, a technique called ballistocardiography (BCG), using a weighing scale. Similar measurements can be made with on-body accelerometers, however these wearable BCG signals are typically more challenging to interpret than whole-body BCG. In this paper, we conducted a small pilot study with four subjects to investigate whether a body sensor network of four accelerometers positioned on the wrist, arm, sternum, and head could improve beat-by-beat PEP prediction beyond that of each sensor alone. Linear models were fitted from the R-J and R-I intervals of the four BCG signals to PEP measured with impedance cardiography from 5-minute recordings after isometric lower-body exercise. Specifically, we found that (i) the RMS error of PEP estimation from the wearable BCG sensors can be reduced by using double integration, (ii) the standard deviation of PEP estimates from R-I intervals was smaller than from R-J intervals, and (iii) linear models combining both R-J and R-I measurements from all sensors resulted in the best average correlation (r(2) = 0.96 ± 0.01) and lowest average root mean square error (2.5 ± 0.8 ms) from 5×2-fold cross validation.


Assuntos
Balistocardiografia/instrumentação , Acelerometria , Adulto , Cardiografia de Impedância/instrumentação , Vestuário , Feminino , Humanos , Modelos Lineares , Masculino , Monitorização Fisiológica/instrumentação , Contração Miocárdica , Projetos Piloto , Processamento de Sinais Assistido por Computador , Sístole , Adulto Jovem
20.
IEEE J Biomed Health Inform ; 19(4): 1435-42, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25265619

RESUMO

Ballistocardiography, the measurement of the reaction forces of the body to cardiac ejection of blood, is one of the few techniques available for unobtrusively assessing the mechanical aspects of cardiovascular health outside clinical settings. Recently, multiple experimental studies involving healthy subjects and subjects with various cardiovascular diseases have demonstrated that the ballistocardiogram (BCG) signal can be used to trend cardiac output, contractility, and beat-by-beat ventricular function for arrhythmias. The majority of these studies has been performed with "fixed" BCG instrumentation-such as weighing scales or chairs-rather than wearable measurements. Enabling wearable, and thus continuous, recording of BCG signals would greatly expand the capabilities of the technique; however, BCG signals measured using wearable devices are morphologically dissimilar to measurements from "fixed" instruments, precluding the analysis and interpretation techniques from one domain to be applied to the other. In particular, the time intervals between the electrocardiogram (ECG) and BCG-namely, the R-J interval, a surrogate for measuring contractility changes-are significantly different for the accelerometer compared to a "fixed" BCG measurement. This paper addresses this need for quantitatively normalizing wearable BCG measurement to "fixed" measurements with a systematic experimental approach. With these methods, the same analysis and interpretation techniques developed over the past decade for "fixed" BCG measurement can be successfully translated to wearable measurements.


Assuntos
Balistocardiografia/métodos , Hemodinâmica/fisiologia , Monitorização Ambulatorial/métodos , Função Ventricular/fisiologia , Adulto , Balistocardiografia/instrumentação , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Monitorização Ambulatorial/instrumentação , Adulto Jovem
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