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1.
Lancet Digit Health ; 2(12): e650-e657, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33328029

RESUMO

BACKGROUND: Heart rate variability, or the variation in the time interval between consecutive heart beats, is a non-invasive dynamic metric of the autonomic nervous system and an independent risk factor for cardiovascular death. Consumer wrist-worn tracking devices using photoplethysmography, such as Fitbit, now provide the unique potential of continuously measuring surrogates of sympathetic and parasympathetic nervous system activity through the analysis of interbeat intervals. We aimed to leverage wrist-worn trackers to derive and describe diverse measures of cardiac autonomic function among Fitbit device users. METHODS: In this cross-sectional study, we collected interbeat interval data that are sent to a central database from Fitbit devices during a randomly selected 24 h period. Age, sex, body-mass index, and steps per day in the 90 days preceding the measurement were extracted. Interbeat interval data were cleaned and heart rate variability features were computed. We analysed heart rate variability metrics across the time (measured via the root mean square of successive RR interval differences [RMSSD] and SD of the RR interval [SDRR]), frequency (measured by high-frequency and low-frequency power), and graphical (measured by Poincare plots) domains. We considered 5 min windows for the time and frequency domain metrics and 60 min measurements for graphical domain metrics. Data from participants were analysed to establish the correlation between heart rate variability metrics and age, sex, time of day, and physical activity. We also determined benchmarks for heart rate variability (HRV) metrics among the users. FINDINGS: We included data from 8 203 261 Fitbit users, collected on Sept 1, 2018. HRV metrics decrease with age, and parasympathetic function declines faster than sympathetic function. We observe a strong diurnal variation in the heart rate variability. SDRR, low-frequency power, and Poincare S2 show a significant variation with sex, whereas such a difference is not seen with RMSSD, high-frequency power, and Poincare S1. For males, when measured from 0600 h to 0700 h, the mean low-frequency power decreased by a factor of 66·5% and high-frequency power decreased by a factor of 82·0% from the age of 20 years to 60 years. For females, the equivalent factors were 69·3% and 80·9%, respectively. Comparing low-frequency power between males and females at the ages of 40-41 years, measured from 0600 h to 0700 h, we found excess power in males, with a Cohen's d effect size of 0·33. For high-frequency power, the equivalent effect size was -0·04. Increased daily physical activity, across age and sex, was highly correlated with improvement in diverse measures of heart rate variability in a dose-dependent manner. We provide benchmark tables for RMSSD, SDRR, high and low frequency powers, and Poincare S1 and S2, separately for different ages and sex and computed at two times of the day. INTERPRETATION: Diverse metrics of cardiac autonomic health can be derived from wrist-worn trackers. Empirical distributions of heart rate variability can potentially be used as a framework for individual-level interpretation. Increased physical activity might yield improvement in heart rate variability and requires prospective trials for confirmation. FUNDING: Fitbit.


Assuntos
Doenças Cardiovasculares , Frequência Cardíaca , Monitorização Ambulatorial/métodos , Sistema Nervoso Parassimpático , Sistema Nervoso Simpático , Telemedicina/métodos , Adolescente , Adulto , Fatores Etários , Idoso , Doenças Cardiovasculares/mortalidade , Doenças Cardiovasculares/fisiopatologia , Estudos Transversais , Exercício Físico/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Sistema Nervoso Parassimpático/fisiopatologia , Fotopletismografia/métodos , Estudos Prospectivos , Fatores Sexuais , Sistema Nervoso Simpático/fisiopatologia , Dispositivos Eletrônicos Vestíveis , Adulto Jovem
2.
Sensors (Basel) ; 20(17)2020 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-32872310

RESUMO

The non-invasive estimation of blood oxygen saturation (SpO2) by pulse oximetry is of vital importance clinically, from the detection of sleep apnea to the recent ambulatory monitoring of hypoxemia in the delayed post-infective phase of COVID-19. In this proof of concept study, we set out to establish the feasibility of SpO2 measurement from the ear canal as a convenient site for long term monitoring, and perform a comprehensive comparison with the right index finger-the conventional clinical measurement site. During resting blood oxygen saturation estimation, we found a root mean square difference of 1.47% between the two measurement sites, with a mean difference of 0.23% higher SpO2 in the right ear canal. Using breath holds, we observe the known phenomena of time delay between central circulation and peripheral circulation with a mean delay between the ear and finger of 12.4 s across all subjects. Furthermore, we document the lower photoplethysmogram amplitude from the ear canal and suggest ways to mitigate this issue. In conjunction with the well-known robustness to temperature induced vasoconstriction, this makes conclusive evidence for in-ear SpO2 monitoring being both convenient and superior to conventional finger measurement for continuous non-intrusive monitoring in both clinical and everyday-life settings.


Assuntos
Meato Acústico Externo , Hipóxia/diagnóstico , Monitorização Fisiológica/instrumentação , Oximetria/instrumentação , Fotopletismografia/instrumentação , Dispositivos Eletrônicos Vestíveis , Adulto , Betacoronavirus/fisiologia , Infecções por Coronavirus/sangue , Infecções por Coronavirus/diagnóstico , Infecções por Coronavirus/terapia , Estudos de Equivalência como Asunto , Estudos de Viabilidade , Feminino , Dedos , Humanos , Hipóxia/sangue , Masculino , Monitorização Fisiológica/métodos , Oximetria/métodos , Oxigênio/análise , Oxigênio/sangue , Pandemias , Fotopletismografia/métodos , Pneumonia Viral/sangue , Pneumonia Viral/diagnóstico , Pneumonia Viral/terapia , Adulto Jovem
3.
PLoS One ; 15(8): e0238569, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32866216

RESUMO

Validation of heart rate responses in wearable technology devices is generally composed of laboratory-based protocols that are steady state in nature and as a result, high accuracy measures are returned. However, there is a need to understand device validity in applied settings that include varied intensities of exercise. The purpose was to determine concurrent heart rate validity during trail running. Twenty-one healthy participants volunteered (female n = 10, [mean (SD)]: age = 31 [11] years, height = 173.0 [7] cm, mass = 75.6 [13] kg). Participants were outfitted with wearable technology devices (Garmin Fenix 5 wristwatch, Jabra Elite Sport earbuds, Motiv ring, Scosche Rhythm+ forearm band, Suunto Spartan Sport watch with accompanying chest strap) and completed a self-paced 3.22 km trail run while concurrently wearing a criterion heart rate strap (Polar H7 heart rate monitor). The trail runs were out-and-back with the first 1.61 km in an uphill direction, and the 1.61 return being downhill in nature. Validity was determined through three methods: Mean Absolute Percent Error (MAPE), Bland-Altman Limits of Agreement (LOA), and Lin's Concordance Coefficient (rC). Validity measures overall are as follows: Garmin Fenix 5 (MAPE = 13%, LOA = -32 to 162, rC = 0.32), Jabra Elite Sport (MAPE = 23%, LOA = -464 to 503, rC = 0.38), Motiv ring (MAPE = 16%, LOA = -52 to 96, rC = 0.29), Scosche Rhythm+ (MAPE = 6%, LOA = -114 to 120, rC = 0.79), Suunto Spartan Sport (MAPE = 2%, LOA = -62 to 61, rC = 0.96). All photoplethysmography-based (PPG) devices displayed poor heart rate agreement during variable intensity trail running. Until technological advances occur in PPG-based devices allowing for acceptable agreement, heart rate in outdoor environments should be obtained using an ECG-based chest strap that can be connected to a wristwatch or other comparable receiver.


Assuntos
Determinação da Frequência Cardíaca/instrumentação , Determinação da Frequência Cardíaca/métodos , Frequência Cardíaca/fisiologia , Corrida/fisiologia , Tecnologia/instrumentação , Tecnologia/métodos , Adulto , Exercício Físico/fisiologia , Teste de Esforço/instrumentação , Teste de Esforço/métodos , Feminino , Monitores de Aptidão Física , Humanos , Masculino , Fotopletismografia/métodos , Dispositivos Eletrônicos Vestíveis
4.
J Med Internet Res ; 22(5): e16443, 2020 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-32348254

RESUMO

BACKGROUND: Continuous photoplethysmography (PPG) monitoring with a wearable device may aid the early detection of atrial fibrillation (AF). OBJECTIVE: We aimed to evaluate the diagnostic performance of a ring-type wearable device (CardioTracker, CART), which can detect AF using deep learning analysis of PPG signals. METHODS: Patients with persistent AF who underwent cardioversion were recruited prospectively. We recorded PPG signals at the finger with CART and a conventional pulse oximeter before and after cardioversion over a period of 15 min (each instrument). Cardiologists validated the PPG rhythms with simultaneous single-lead electrocardiography. The PPG data were transmitted to a smartphone wirelessly and analyzed with a deep learning algorithm. We also validated the deep learning algorithm in 20 healthy subjects with sinus rhythm (SR). RESULTS: In 100 study participants, CART generated a total of 13,038 30-s PPG samples (5850 for SR and 7188 for AF). Using the deep learning algorithm, the diagnostic accuracy, sensitivity, specificity, positive-predictive value, and negative-predictive value were 96.9%, 99.0%, 94.3%, 95.6%, and 98.7%, respectively. Although the diagnostic accuracy decreased with shorter sample lengths, the accuracy was maintained at 94.7% with 10-s measurements. For SR, the specificity decreased with higher variability of peak-to-peak intervals. However, for AF, CART maintained consistent sensitivity regardless of variability. Pulse rates had a lower impact on sensitivity than on specificity. The performance of CART was comparable to that of the conventional device when using a proper threshold. External validation showed that 94.99% (16,529/17,400) of the PPG samples from the control group were correctly identified with SR. CONCLUSIONS: A ring-type wearable device with deep learning analysis of PPG signals could accurately diagnose AF without relying on electrocardiography. With this device, continuous monitoring for AF may be promising in high-risk populations. TRIAL REGISTRATION: ClinicalTrials.gov NCT04023188; https://clinicaltrials.gov/ct2/show/NCT04023188.


Assuntos
Fibrilação Atrial/diagnóstico , Aprendizado Profundo/normas , Fotopletismografia/métodos , Dispositivos Eletrônicos Vestíveis/normas , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudo de Prova de Conceito , Estudos Prospectivos
5.
J Med Eng Technol ; 44(2): 82-93, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32077775

RESUMO

Hand-ischemia and artery-thrombosis are serious complications of hand artery cannulation/grafting. Screening the patency of hand arteries reduces the complications. Modified Allen Test (MAT), Barbeau's test, and Doppler/Duplex-ultrasonic test screen hand arterial patency. Each of them, however, either lacks objectivity, requires subject cooperation, or is not readily available in operating rooms. In this pilot study, we aim to provide a novel, objective, reliable, and inexpensive alternative using differential photo-plethysmography (PPG) measurement, and an artery selection algorithm. For 11 participants, MAT was executed, and PPG measurements of the thumb and little fingers were recorded for left and right hands separately. For each hand, four evaluations were conducted, then fed into the artery selection algorithm. Our proposed procedure has shown congruent results with the anatomy of blood circulation. It identified two arteries in two participants causing >50% blood reduction in the hand due to their occlusion. It also showed an elevated risk of accessing an artery in another 8 participants. Once the results of this study are confirmed in larger samples, the proposed procedure/algorithm may provide many indicators of the hand blood circulation, the effect of an artery occlusion on the hand, and a recommendation for selecting the best artery to access with the lowest possible complications.


Assuntos
Algoritmos , Circulação Colateral/fisiologia , Fotopletismografia/métodos , Adulto , Feminino , Humanos , Masculino , Projetos Piloto , Adulto Jovem
6.
Sci Rep ; 10(1): 2118, 2020 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-32034184

RESUMO

We studied the properties of low-frequency (LF) heart rate variability (HRV) and photoplethysmographic waveform variability (PPGV) and their interaction under conditions where the hemodynamic connection between them is obviously absent, as well as the LF regulation of PPGV in the absence of heart function. The parameters of HRV and finger PPGV were evaluated in 10 patients during cardiac surgery under cardiopulmonary bypass (on-pump cardiac surgery) with or without cardioplegia. The following spectral indices of PPGV and HRV were ertimated: the total spectral power (TP), the high-frequency (HF) and the LF ranges of TP in percents (HF% and LF%), and the LF/HF ratio. We assessed also the index S of synchronization between the LF oscillations in finger photoplethysmogram (PPG) and heart rate (HR) signals. The analysis of directional couplings was carried out using the methods of phase dynamics modeling. It is shown that the mechanisms leading to the occurrence of oscillations in the LF range of PPGV are independent of the mechanisms causing oscillations in the LF range of HRV. At the same time, the both above-mentioned LF oscillations retain their activity under conditions of artificial blood circulation and cardioplegia (the latter case applies only to LF oscillations in PPG). In artificial blood circulation, there was a coupling from the LF oscillations in PPG to those in HR, whereas the coupling in the opposite direction was absent. The coupling from the LF oscillations in PPG to those in HR has probably a neurogenic nature, whereas the opposite coupling has a hemodynamic nature (due to cardiac output).


Assuntos
Procedimentos Cirúrgicos Cardíacos/métodos , Parada Cardíaca Induzida/efeitos adversos , Parada Cardíaca/fisiopatologia , Frequência Cardíaca/fisiologia , Fotopletismografia/métodos , Débito Cardíaco/fisiologia , Ponte Cardiopulmonar/métodos , Dedos/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade
7.
Clin Exp Hypertens ; 42(6): 512-518, 2020 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-31941385

RESUMO

OBJECTIVE: In recent times, new methods of blood pressure measurements have been introduced, including cuffless blood pressure (BP) measurement device using pulse transit time (PTT) for calculation of BP values. However, it is still unknown how values obtained with a new cuffless device compare with standard ambulatory measurements in children. The main aim of the study was to investigate whether BP values measured by a cuffless PTT device are comparable with measurements by a standard upper arm cuff-based BP device. METHODS: Thirty children were prospectively included. Blood pressure measurements using the cuffless device (Somnotouch-NIBP) and cuff-based standard device (Omron 907) were performed simultaneously on the left and right arm. RESULTS: Mean systolic BP of the standard measurements was 123,47 ± 14,91 mmHg and 127,48 ± 15,98 mmHg (p < .001) measured by cuffless method. Mean diastolic BP of the standard ABPM measurements was 66,88 ± 11,86 mmHg and 68,52 ± 12,36 mmHg (p < .001). There were significant positive correlations between standard and cuffless measurements. CONCLUSION: The results show that the created PWV-BP function produces a significant correlation between BP derived from the PWV and the SBP measured by sphygmomanometry. When applying this device in clinical practice, one may keep in mind that the reported mean values over 24 hours, awake and asleep time are not directly interchangeable with cuff-based standard 24-hour BP values. The measured BP values were higher by the new technique. Although differences in SBP between both methods reached values up to 20 mmHg, we think that the development of a cuffless BP monitoring system will provide novel solutions in various medical situations.


Assuntos
Determinação da Pressão Arterial , Hipertensão , Esfigmomanômetros , Adolescente , Pressão Sanguínea/fisiologia , Determinação da Pressão Arterial/instrumentação , Determinação da Pressão Arterial/métodos , Determinação da Pressão Arterial/normas , Criança , Relógios Circadianos/fisiologia , Eletrocardiografia/métodos , Feminino , Humanos , Hipertensão/diagnóstico , Hipertensão/fisiopatologia , Masculino , Fotopletismografia/métodos , Análise de Onda de Pulso/métodos , Esfigmomanômetros/classificação , Esfigmomanômetros/normas
8.
Appl Spectrosc ; 74(1): 23-33, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30409032

RESUMO

Dynamic spectra (DS) can greatly reduce the influence of individual differences and the measurement environment by extracting the absorbance of pulsating blood at multiple wavelengths, and it is expected to achieve noninvasive detection of blood components. Extracting high-quality DS is the prerequisite for improving detection accuracy. This paper proposed an optimizing differential extraction method in view of the deficiency of existing extraction methods. In the proposed method, the sub-dynamic spectrum (sDS) is composed by sequentially extracting the absolute differences of two sample points corresponding to the height of the half peak on the two sides of the lowest point in each period of the logarithm photoplethysmography signal. The study was based on clinical trial data from 231 volunteers. Single-trial extraction method, original differential extraction method, and optimizing differential extraction method were used to extract DS from the volunteers' experimental data. Partial least squares regression (PLSR) and radial basis function (RBF) neural network were used for modeling. According to the effect of PLSR modeling, by extracting DS using the proposed method, the correlation coefficient of prediction set (Rp) has been improved by 17.33% and the root mean square error of prediction set has been reduced by 7.10% compared with the original differential extraction method. Compared with the single-trial extraction method, the correlation coefficient of calibration set (Rc) has increased from 0.747659 to 0.8244, with an increase of 10.26%, while the correlation coefficient of prediction set (Rp) decreased slightly by 3.22%, much lower than the increase of correction set. The result of the RBF neural network modeling also shows that the accuracy of the optimizing differential method is better than the other two methods both in calibration set and prediction set. In general, the optimizing differential extraction method improves the data utilization and credibility compared with the existing extraction methods, and the modeling effect is better than the other two methods.


Assuntos
Testes Hematológicos/métodos , Fotopletismografia/métodos , Processamento de Sinais Assistido por Computador , Testes Hematológicos/instrumentação , Testes Hematológicos/estatística & dados numéricos , Humanos , Análise dos Mínimos Quadrados , Redes Neurais de Computação , Fibras Ópticas , Fotopletismografia/estatística & dados numéricos , Fluxo Pulsátil , Razão Sinal-Ruído
9.
Blood Press ; 29(1): 55-62, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31402715

RESUMO

Background: It is believed that the intensity of oscillations in the photoplethysmographic waveform variability reflects the activity of vascular regulatory mechanisms. However, the relationship of such fluctuations with the state of health is poorly understood.Purpose: The aim of our study was to assess the possibility of using spectral indices that reflect the intensity of oscillations of the photoplethysmographic waveform variability at frequencies 0.04-0.4 Hz as markers of hypertension and coronary artery disease. We did not study women to exclude the influence of menopause and sex hormones on the results.Materials and Methods: We compared synchronous 10-minute records of finger photoplethysmogram and respiration at rest in 30 healthy males (48.8 ± 4.5 years; data presented as Mean ± SD) versus 30 patients with hypertension (aged 49.0 ± 4.3 years) versus 30 patients with stable coronary artery disease (49.2 ± 4.8 years). Percentages of high-frequency and low-frequency ranges in the total power of photoplethysmographic waveform variability spectrum (HF% and LF%), and LF/HF ratio were assessed.Results: HF% are subject to by 2- to 5-fold increase in hypertensive patients (p < .001) and up to an 8-fold increase in patients with coronary artery disease (p < .001) when compared with healthy persons. On the contrary, LF% is reduced by 1.5-5 times in all patients when compared with healthy people (p < .001). We identified cut-off points for each photoplethysmographic index to distinguish patients with coronary artery disease or hypertension from healthy subjects. Multiple logistic regression models based on photoplethysmographic waveform variability indices had sufficient sensitivity and specificity for patients with hypertension or coronary artery disease.Conclusion: Frequency-domain indices of photoplethysmographic waveform variability (in particular, HF%, LF%, and LF/HF) are sufficiently sensitive and specific markers of hypertension and coronary artery disease in adult males.


Assuntos
Doença da Artéria Coronariana/diagnóstico , Hipertensão/diagnóstico , Fotopletismografia/métodos , Adulto , Estudos de Casos e Controles , Dedos , Humanos , Masculino , Pessoa de Meia-Idade , Respiração , Sensibilidade e Especificidade
10.
Am J Emerg Med ; 38(3): 526-533, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31138516

RESUMO

OBJECTIVE: This work investigates the potential of photoplethysmography (PPG) to detect a spontaneous pulse from the finger, nose or ear in order to support pulse checks during cardiopulmonary resuscitation (CPR). METHODS: In a prospective single-center cross-sectional study, PPG signals were acquired from cardiac arrest victims who underwent CPR. The PPG signals were analyzed and compared to arterial blood pressure (ABP) signals as a reference during three distranaisco; Date: 2/2/2020; Time:18:44:23inct phases of CPR: compression pauses, on-going compressions and at very low arterial blood pressure. Data analysis was based on a qualitative subjective visual description of similarities of the frequency content of PPG and ABP waveform. RESULTS: In 9 patients PPG waveforms corresponded to ABP waveforms during normal blood pressures. During ABP in the clinically challenging range of 60 to 90 mmHg and during chest compressions and pauses, PPG continued to resemble ABP, as both signals showed similar frequency components as a result of chest compressions as well as cardiac activity. Altogether 1199 s of PPG data in compression pauses were expected to show a spontaneous pulse, of which 732 s (61%) of data were artifact-free and showed the spontaneous pulse as visible in the ABP. CONCLUSIONS: PPG signals at all investigated sites can indicate pulse presence at the moment the heart resumes beating as verified via the ABP signal. Therefore, PPG may provide decision support during CPR, especially related to preventing and shortening interruptions for unnecessary pulse checks. This could have impact on CPR outcome and should further be investigated.


Assuntos
Reanimação Cardiopulmonar/métodos , Parada Cardíaca Extra-Hospitalar/terapia , Fotopletismografia/métodos , Pulso Arterial/métodos , Adulto , Idoso , Estudos Transversais , Serviço Hospitalar de Emergência , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos
11.
IEEE Trans Biomed Circuits Syst ; 13(6): 1552-1562, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31796415

RESUMO

This study designs a low-power photoplethysmography (PPG) sensor based on the error compensation method for heartbeat interval acquisition. To perform heartbeat monitoring in daily life, it is necessary to obtain long-term and accurate heartbeat interval data with low power consumption, because of the limited size and battery capacity of the PPG sensor. Effective reduction in the power consumption of the sensor requires the duty-cycled LEDs and lowering pulse repetition frequency (PRF), i.e., decreasing the sampling rate. However, these methods reduce the accuracy of the heartbeat interval measurement because of signal-to-noise ratio (SNR) degradation and sampling errors. We propose an algorithm for heartbeat interval error compensation and incorporate a low-noise readout circuit to improve SNR. The readout circuit uses current integration to achieve low duty-cycle LED driving. A correlated double sampling (CDS) is introduced to minimize the random noise arising from the switching operation of the integration circuit. An error compensation method based on the PPG waveform similarity is also introduced using the autocorrelation and linear interpolation. The measurement results obtained from nine subjects show that a total current consumption of 28.2 µA is achieved with a 20-Hz PRF and 0.3% LED duty cycle. The proposed design effectively reduces the mean absolute error (MAE) of the heartbeat interval to an average of 6.2 ms.


Assuntos
Frequência Cardíaca , Fotopletismografia/instrumentação , Fontes de Energia Elétrica , Desenho de Equipamento , Humanos , Fotopletismografia/métodos , Processamento de Sinais Assistido por Computador , Razão Sinal-Ruído
12.
Sensors (Basel) ; 19(24)2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31847474

RESUMO

Blood pressure is an extremely important blood hemodynamic parameter. The pulse wave contains abundant blood-pressure information, and the convenience and non-invasivity of its measurement make it ideal for non-invasive continuous monitoring of blood pressure. Based on combined photoplethysmography and electrocardiogram signals, this study aimed to extract the waveform information, introduce individual characteristics, and construct systolic and diastolic blood-pressure (SBP and DBP) estimation models using the back-propagation error (BP) neural network. During the model construction process, the mean impact value method was employed to investigate the impact of each feature on the model output and reduce feature redundancy. Moreover, the multiple population genetic algorithm was applied to optimize the BP neural network and determine the initial weights and threshold of the network. Finally, the models were integrated for further optimization to generate the final individualized continuous blood-pressure monitoring models. The results showed that the predicted values of the model in this study correlated significantly with the measured values of the electronic sphygmomanometer. The estimation errors of the model met the Association for the Advancement of Medical Instrumentation (AAMI) criteria (the SBP error was 2.5909 ± 3.4148 mmHg, and the DBP error was 2.6890 ± 3.3117 mmHg) and the Grade A British Hypertension Society criteria.


Assuntos
Pressão Sanguínea/fisiologia , Eletrocardiografia/métodos , Fotopletismografia/métodos , Algoritmos , Determinação da Pressão Arterial/métodos , Humanos
13.
J Med Syst ; 44(1): 14, 2019 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-31811401

RESUMO

In this study, we proposed a new method for multi-class classification of sleep apnea/hypopnea events based on a long short-term memory (LSTM) using photoplethysmography (PPG) signals. The three-layer LSTM model was used with batch-normalization and dropout to classify the multi-class events including normal, apnea, and hypopnea. The PPG signals, which were measured by the nocturnal polysomnography with 7 h from 82 patients suffered from sleep apnea, were used to model training and evaluation. The performance of the proposed method was evaluated on the training set from 63 patients and test set from 13 patients. The results of the LSTM model showed the following high performances: the positive predictive value of 94.16% for normal, 81.38% for apnea, and 97.92% for hypopnea; sensitivity of 86.03% for normal, 91.24% for apnea, and 99.38% for hypopnea events. The proposed method had especially higher performance of hypopnea classification which had been a drawback of previous studies. Furthermore, it can be applied to a system that can classify sleep apnea/hypopnea and normal events automatically without expert's intervention at home.


Assuntos
Memória de Curto Prazo , Fotopletismografia/métodos , Respiração , Síndromes da Apneia do Sono/classificação , Aprendizado Profundo , Humanos , Sensibilidade e Especificidade
14.
Appl Opt ; 58(34): 9398-9405, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31873531

RESUMO

Recent advances in the development of ultra-compact semiconductor lasers and technology of printed flexible hybrid electronics have opened broad perspectives for the design of new pulse oximetry and photoplethysmography devices. Conceptual design of optical diagnostic devices requires careful selection of various technical parameters, including spectral range; polarization and intensity of incident light; actual size, geometry, and sensitivity of the detector; and mutual position of the source and detector on the surface of skin. In the current study utilizing a unified Monte Carlo computational tool, we explore the variations in diagnostic volume due to arterial blood pulsation for typical transmitted and back-scattered probing configurations in a human finger. The results of computational studies show that the variations in diagnostic volumes due to arterial pulse wave are notably (up to 45%) different in visible and near-infrared spectral ranges in both transmitted and back-scattered probing geometries. While these variations are acceptable for relative measurements in pulse oximetry and/or photoplethysmography, for absolute measurements, an alignment normalization of diagnostic volume is required and can be done by a computational approach utilized in the framework of the current study.


Assuntos
Artérias/fisiologia , Frequência Cardíaca/fisiologia , Oximetria/métodos , Oxigênio/sangue , Fotopletismografia/métodos , Fluxo Pulsátil/fisiologia , Humanos , Método de Monte Carlo
15.
Rev. cuba. inform. méd ; 11(2)jul.-dic. 2019. tab, graf
Artigo em Inglês | LILACS, CUMED | ID: biblio-1093315

RESUMO

Background: Age-related changes in the vascular network have been widely documented, however, nonlinear identification has been poorly applied to the analysis of cardiovascular signals. Objective: To determine the impact of age on spectral components of Noise-free realizations (NFR) obtained from photoplethysmographic signals, summarized in the Kernel Complexity Regressive Index (KCRIndex). Methods: With 190 apparently healthy participants (9 to 89 years) from Orense, Spain, Photoplethysmographic signals were recorded during 5 minutes in supine position using Nellcor-395 pulse oximeter; signals were digitized at 1000 Hz, and furtherly submitted to nonlinear identification via a kernel nonlinear autoregressive estimator. KCRIndex is defined as the average of at least three negative slope values at the NFR log-log spectrum in the 9 to 25 Hz frequency region. Results: KCRIndex decreased with age in a linear fashion and did not differ between genders. The regression line obtained was KCRIndex=-0.025*age+6.868 (r=-0.751). Conclusions: KCRIndex, is strongly correlated with age, thus opening up new possibilities for cardiovascular exploration at primary health care settings and even on open field conditions(AU)


Antecedentes: los cambios relacionados con la edad en la red vascular se han documentado ampliamente, sin embargo, la identificación no lineal solo se ha aplicado de manera esporádica al análisis de las señales cardiovasculares. Objetivo: determinar los cambios con la edad en los componentes espectrales de las realizaciones sin ruido (NFR) obtenidas a partir de señales fotopletismográficas, resumidas en el índice regresivo de la complejidad por núcleos (KCRIndex). Métodos: Con 190 participantes aparentemente sanos (de 9 a 89 años) residentes en Orense, España, se registraron señales fotopletismográficas durante 5 minutos en posición supina usando un oxímetro de pulso Nellcor-395; las señales se digitalizaron a 1000 Hz, y se sometieron a identificación no lineal a través de un estimador autorregresivo no lineal por núcleos. El KCRIndex se define como el promedio de al menos tres valores de pendiente negativos en el espectro log-log de NFR en la región de frecuencia de 9 a 25 Hz. Resultados: KCRIndex disminuyó con la edad de forma lineal y no difirió entre géneros. La línea de regresión obtenida fue KCRIndex = -0.025 * edad + 6.868 (r = -0.751). Conclusiones: Este índice propuesto está fuertemente correlacionado con la edad, lo que abre nuevas posibilidades para la exploración cardiovascular en entornos de atención primaria de salud e incluso en condiciones de campo(AU)


Assuntos
Fotopletismografia/métodos , Dinâmica não Linear , Distribuição por Idade , Estatísticas não Paramétricas
16.
Sci Rep ; 9(1): 16346, 2019 11 08.
Artigo em Inglês | MEDLINE | ID: mdl-31705001

RESUMO

The pulse arrival time (PAT), pre-ejection period (PEP) and pulse transit time (PTT) are calculated using on-body continuous wave radar (CWR), Photoplethysmogram (PPG) and Electrocardiogram (ECG) sensors for wearable continuous systolic blood pressure (SBP) measurements. The CWR and PPG sensors are placed on the sternum and left earlobe respectively. This paper presents a signal processing method based on wavelet transform and adaptive filtering to remove noise from CWR signals. Experimental data are collected from 43 subjects in various static postures and 26 subjects doing 6 different exercise tasks. Two mathematical models are used to calculate SBPs from PTTs/PATs. For 38 subjects participating in posture tasks, the best cumulative error percentage (CEP) is 92.28% and for 21 subjects participating in exercise tasks, the best CEP is 82.61%. The results show the proposed method is promising in estimating SBP using PTT. Additionally, removing PEP from PAT leads to improving results by around 9%. The CWR sensors present a low-power, continuous and potentially wearable system with minimal body contact to monitor aortic valve mechanical activities directly. Results of this study, of wearable radar sensors, demonstrate the potential superiority of CWR-based PEP extraction for various medical monitoring applications, including BP measurement.


Assuntos
Algoritmos , Determinação da Pressão Arterial/métodos , Pressão Sanguínea , Exercício Físico , Monitorização Fisiológica/métodos , Fotopletismografia/métodos , Postura , Adulto , Idoso , Feminino , Voluntários Saudáveis , Frequência Cardíaca , Humanos , Masculino , Pessoa de Meia-Idade , Análise de Onda de Pulso , Radar , Processamento de Sinais Assistido por Computador
17.
PLoS One ; 14(11): e0225592, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31756239

RESUMO

Remote photoplethysmography (rPPG) allows contactless monitoring of human cardiac activity through a video camera. In this study, we assessed the accuracy and precision for heart rate measurements of the only consumer product available on the market, namely the FacereaderTM rPPG by Noldus, with respect to a gold standard electrocardiograph. Twenty-four healthy participants were asked to sit in front of a computer screen and alternate two periods of rest with two stress tests (i.e. Go/No-Go task), while their heart rate was simultaneously acquired for 20 minutes using the ECG criterion measure and the FacereaderTM rPPG. Results show that the FacereaderTM rPPG tends to overestimate lower heart rates and underestimate higher heart rates compared to the ECG. The Facereader™ rPPG revealed a mean bias of 9.8 bpm, the 95% limits of agreement (LoA) ranged from almost -30 up to +50 bpm. These results suggest that whilst the rPPG FacereaderTM technology has potential for contactless heart rate monitoring, its predictions are inaccurate for higher heart rates, with unacceptable precision across the entire range, rendering its estimates unreliable for monitoring individuals.


Assuntos
Frequência Cardíaca , Fotopletismografia/métodos , Adulto , Eletrocardiografia , Feminino , Humanos , Masculino , Adulto Jovem
18.
Sleep ; 42(12)2019 12 24.
Artigo em Inglês | MEDLINE | ID: mdl-31579900

RESUMO

Wearable, multisensor, consumer devices that estimate sleep are now commonplace, but the algorithms used by these devices to score sleep are not open source, and the raw sensor data is rarely accessible for external use. As a result, these devices are limited in their usefulness for clinical and research applications, despite holding much promise. We used a mobile application of our own creation to collect raw acceleration data and heart rate from the Apple Watch worn by participants undergoing polysomnography, as well as during the ambulatory period preceding in lab testing. Using this data, we compared the contributions of multiple features (motion, local standard deviation in heart rate, and "clock proxy") to performance across several classifiers. Best performance was achieved using neural nets, though the differences across classifiers were generally small. For sleep-wake classification, our method scored 90% of epochs correctly, with 59.6% of true wake epochs (specificity) and 93% of true sleep epochs (sensitivity) scored correctly. Accuracy for differentiating wake, NREM sleep, and REM sleep was approximately 72% when all features were used. We generalized our results by testing the models trained on Apple Watch data using data from the Multi-ethnic Study of Atherosclerosis (MESA), and found that we were able to predict sleep with performance comparable to testing on our own dataset. This study demonstrates, for the first time, the ability to analyze raw acceleration and heart rate data from a ubiquitous wearable device with accepted, disclosed mathematical methods to improve accuracy of sleep and sleep stage prediction.


Assuntos
Aceleração , Interpretação Estatística de Dados , Frequência Cardíaca/fisiologia , Fotopletismografia/métodos , Fases do Sono/fisiologia , Dispositivos Eletrônicos Vestíveis , Adulto , Algoritmos , Eletroencefalografia/métodos , Feminino , Previsões , Humanos , Masculino , Pessoa de Meia-Idade , Polissonografia/métodos , Adulto Jovem
19.
Sensors (Basel) ; 19(19)2019 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-31590351

RESUMO

Blood pressure wave monitoring provides interesting information about the patient's cardiovascular function. For this reason, this article proposes a non-invasive device capable of capturing the vibrations (pressure waves) produced by the carotid artery by means of a pressure sensor encapsulated in a closed dome filled with air. When the device is placed onto the outer skin of the carotid area, the vibrations of the artery will exert a deformation in the dome, which, in turn, will lead to a pressure increase in its inner air. Then, the sensor inside the dome captures this pressure increase. By combining the blood pressure wave obtained with this device together with the ECG signal, it is possible to help the screening of the cardiovascular system, obtaining parameters such as heart rate variability (HRV) and pulse transit time (PTT). The results show how the pressure wave has been successfully obtained in the carotid artery area, discerning the characteristic points of this signal. The features of this device compare well with previous works by other authors. The main advantages of the proposed device are the reduced size, the cuffless condition, and the potential to be a continuous ambulatory device. These features could be exploited in ambulatory tests.


Assuntos
Monitorização Ambulatorial da Pressão Arterial/métodos , Pressão Sanguínea/fisiologia , Monitorização Fisiológica , Análise de Onda de Pulso/métodos , Adulto , Monitorização Ambulatorial da Pressão Arterial/instrumentação , Eletrocardiografia/métodos , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , Fotopletismografia/métodos , Análise de Onda de Pulso/instrumentação , Transdutores
20.
Biosensors (Basel) ; 9(4)2019 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-31581652

RESUMO

Current pulse oximeter sensors can be challenged in working accurately and continuously in situations of reduced periphery perfusion, especially among anaesthetised patients. A novel tracheal photoplethysmography (PPG) sensor has been developed in an effort to address the limitations of current pulse oximeters. The sensor has been designed to estimate oxygen saturation (SpO2) and pulse rate, and has been manufactured on a flexible printed circuit board (PCB) that can adhere to a standard endotracheal (ET) tube. A pilot clinical trial was carried out as a feasibility study on 10 anaesthetised patients. Good quality PPGs from the trachea were acquired at red and infrared wavelengths in all patients. The mean SpO2 reading for the ET tube was 97.1% (SD 1.0%) vs. the clinical monitor at 98.7% (SD 0.7%). The mean pulse rate for the ET sensor was 65.4 bpm (SD 10.0 bpm) vs. the clinical monitor at 64.7 bpm (SD 9.9 bpm). This study supports the hypothesis that the human trachea could be a suitable monitoring site of SpO2 and other physiological parameters, at times where the periphery circulation might be compromised.


Assuntos
Técnicas Biossensoriais , Oximetria/instrumentação , Fotopletismografia/instrumentação , Traqueia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Monitorização Fisiológica/instrumentação , Monitorização Fisiológica/métodos , Oximetria/métodos , Fotopletismografia/métodos , Processamento de Sinais Assistido por Computador , Sinais Vitais
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