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Lu L, Zhu T, Morelli D, Creagh A, Liu Z, Yang J, Liu F, Zhang YT, Clifton DA. Uncertainties in the Analysis of Heart Rate Variability: A Systematic Review. IEEE Rev Biomed Eng 2024; 17:180-196. [PMID: 37186539 DOI: 10.1109/rbme.2023.3271595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Heart rate variability (HRV) is an important metric with a variety of applications in clinical situations such as cardiovascular diseases, diabetes mellitus, and mental health. HRV data can be potentially obtained from electrocardiography and photoplethysmography signals, then computational techniques such as signal filtering and data segmentation are used to process the sampled data for calculating HRV measures. However, uncertainties arising from data acquisition, computational models, and physiological factors can lead to degraded signal quality and affect HRV analysis. Therefore, it is crucial to address these uncertainties and develop advanced models for HRV analysis. Although several reviews of HRV analysis exist, they primarily focus on clinical applications, trends in HRV methods, or specific aspects of uncertainties such as measurement noise. This paper provides a comprehensive review of uncertainties in HRV analysis, quantifies their impacts, and outlines potential solutions. To the best of our knowledge, this is the first study that presents a holistic review of uncertainties in HRV methods and quantifies their impacts on HRV measures from an engineer's perspective. This review is essential for developing robust and reliable models, and could serve as a valuable future reference in the field, particularly for dealing with uncertainties in HRV analysis.
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2
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Hammour G, Mandic DP. An In-Ear PPG-Based Blood Glucose Monitor: A Proof-of-Concept Study. SENSORS (BASEL, SWITZERLAND) 2023; 23:s23063319. [PMID: 36992029 PMCID: PMC10057625 DOI: 10.3390/s23063319] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/12/2023] [Accepted: 03/17/2023] [Indexed: 06/12/2023]
Abstract
Monitoring diabetes saves lives. To this end, we introduce a novel, unobtrusive, and readily deployable in-ear device for the continuous and non-invasive measurement of blood glucose levels (BGLs). The device is equipped with a low-cost commercially available pulse oximeter whose infrared wavelength (880 nm) is used for the acquisition of photoplethysmography (PPG). For rigor, we considered a full range of diabetic conditions (non-diabetic, pre-diabetic, type I diabetic, and type II diabetic). Recordings spanned nine different days, starting in the morning while fasting, up to a minimum of a two-hour period after eating a carbohydrate-rich breakfast. The BGLs from PPG were estimated using a suite of regression-based machine learning models, which were trained on characteristic features of PPG cycles pertaining to high and low BGLs. The analysis shows that, as desired, an average of 82% of the BGLs estimated from PPG lie in region A of the Clarke error grid (CEG) plot, with 100% of the estimated BGLs in the clinically acceptable CEG regions A and B. These results demonstrate the potential of the ear canal as a site for non-invasive blood glucose monitoring.
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Zavanelli N, Lee SH, Guess M, Yeo WH. Soft wireless sternal patch to detect systemic vasoconstriction using photoplethysmography. iScience 2023; 26:106184. [PMID: 36879814 PMCID: PMC9985026 DOI: 10.1016/j.isci.2023.106184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 01/16/2023] [Accepted: 02/07/2023] [Indexed: 02/16/2023] Open
Abstract
Vasoconstriction is a crucial physiological process that serves as the body's primary blood pressure regulation mechanism and a key marker of numerous harmful health conditions. The ability to detect vasoconstriction in real time would be crucial for detecting blood pressure, identifying sympathetic arousals, characterizing patient wellbeing, detecting sickle cell anemia attacks early, and identifying complications caused by hypertension medications. However, vasoconstriction manifests weakly in traditional photoplethysmogram (PPG) measurement locations, like the finger, toe, and ear. Here, we report a wireless, fully integrated, soft sternal patch to capture PPG signals from the sternum, an anatomical region that exhibits a robust vasoconstrictive response. With healthy controls, the device is highly capable of detecting vasoconstriction induced endogenously and exogenously. Furthermore, in overnight trials with patients with sleep apnea, the device shows a high agreement (r2 = 0.74) in vasoconstriction detection with a commercial system, demonstrating its potential use in portable, continuous, long-term vasoconstriction monitoring.
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Affiliation(s)
- Nathan Zavanelli
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30024, USA.,IEN Center for Human-Centric Interfaces and Engineering at the Institute for Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Sung Hoon Lee
- IEN Center for Human-Centric Interfaces and Engineering at the Institute for Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, GA 30332, USA.,School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Matthew Guess
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30024, USA.,IEN Center for Human-Centric Interfaces and Engineering at the Institute for Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Woon-Hong Yeo
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30024, USA.,IEN Center for Human-Centric Interfaces and Engineering at the Institute for Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, GA 30332, USA.,Wallace H. Coulter Department of Biomedical Engineering, Georgia Tech and Emory University School of Medicine, Atlanta, GA 30332, USA.,Parker H. Petit Institute for Bioengineering and Biosciences, Neural Engineering Center, Institute for Materials, Institute for Robotics and Intelligent Machines, Georgia Institute of Technology, Atlanta, GA 30332, USA
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4
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Sarkar M, Assaad M. Noninvasive Non-Contact SpO 2 Monitoring Using an Integrated Polarization-Sensing CMOS Imaging Sensor. SENSORS (BASEL, SWITZERLAND) 2022; 22:7796. [PMID: 36298147 PMCID: PMC9608125 DOI: 10.3390/s22207796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Revised: 10/05/2022] [Accepted: 10/06/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND In the diagnosis and primary health care of an individual, estimation of the pulse rate and blood oxygen saturation (SpO2) is critical. The pulse rate and SpO2 are determined by methods including photoplethysmography (iPPG), light spectroscopy, and pulse oximetry. These devices need to be compact, non-contact, and noninvasive for real-time health monitoring. Reflection-based iPPG is becoming popular as it allows non-contact estimation of the heart rate and SpO2. Most iPPG methods capture temporal data and form complex computations, and thus real-time measurements and spatial visualization are difficult. METHOD In this research work, reflective mode polarized imaging-based iPPG is proposed. For polarization imaging, a custom image sensor with wire grid polarizers on each pixel is designed. Each pixel has a wire grid of varying transmission axes, allowing phase detection of the incoming light. The phase information of the backscattered light from the fingertips of 12 healthy volunteers was recorded in both the resting as well as the excited states. These data were then processed using MATLAB 2021b software. RESULTS The phase information provides quantitative information on the reflection from the superficial and deep layers of skin. The ratio of deep to superficial layer backscattered phase information is shown to be directly correlated and linearly increasing with an increase in the SpO2 and heart rate. CONCLUSIONS The phase-based measurements help to monitor the changes in the resting and excited state heart rate and SpO2 in real time. Furthermore, the use of the ratio of phase information helps to make the measurements independent of the individual skin traits and thus increases the accuracy of the measurements. The proposed iPPG works in ambient light, relaxing the instrumentation requirement and helping the system to be compact and portable.
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Affiliation(s)
- Mukul Sarkar
- Electrical Engineering Department, IIT Delhi, Hauz Khas, New Delhi 110016, India
| | - Maher Assaad
- Department of Electrical and Computer Engineering, Ajman University, Ajman P.O. Box 346, United Arab Emirates
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Armañac-Julián P, Kontaxis S, Rapalis A, Marozas V, Laguna P, Bailón R, Gil E, Lázaro J. Reliability of pulse photoplethysmography sensors: Coverage using different setups and body locations. FRONTIERS IN ELECTRONICS 2022. [DOI: 10.3389/felec.2022.906324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Pulse photoplethysmography (PPG) is a simple and economical technique for obtaining cardiovascular information. In fact, PPG has become a very popular technology among wearable devices. However, the PPG signal is well-known to be very vulnerable to artifacts, and a good quality signal cannot be expected for most of the time in daily life. The percentage of time that a given measurement can be estimated (e.g., pulse rate) is denoted coverage (C), and it is highly dependent on the subject activity and on the configuration of the sensor, location, and stability of contact. This work aims to quantify the coverage of PPG sensors, using the simultaneously recorded electrocardiogram as a reference, with the PPG recorded at different places in the body and under different stress conditions. While many previous works analyzed the feasibility of PPG as a surrogate for heart rate variability analysis, there exists no previous work studying coverage to derive other cardiovascular indices. We report the coverage not only for estimating pulse rate (PR) but also for estimating pulse arrival time (PAT) and pulse amplitude variability (PAV). Three different datasets are analyzed for this purpose, consisting of a tilt-table test, an acute emotional stress test, and a heat stress test. The datasets include 19, 120, and 51 subjects, respectively, with PPG at the finger and at the forehead for the first two datasets and at the earlobe, in addition, for the latter. C ranges from 70% to 90% for estimating PR. Regarding the estimation of PAT, C ranges from 50% to 90%, and this is very dependent on the PPG sensor location, PPG quality, and the fiducial point (FP) chosen for the delineation of PPG. In fact, the delineation of the FP is critical in time for estimating derived series such as PAT due to the small dynamic range of these series. For the estimation of PAV, the C rates are between 70% and 90%. In general, lower C rates have been obtained for the PPG at the forehead. No difference in C has been observed between using PPG at the finger or at the earlobe. Then, the benefits of using either will depend on the application. However, different C rates are obtained using the same PPG signal, depending on the FP chosen for delineation. Lower C is reported when using the apex point of the PPG instead of the maximum flow velocity or the basal point, with a difference from 1% to even 10%. For further studies, each setup should first be analyzed and validated, taking the results and guidelines presented in this work into account, to study the feasibility of its recording devices with respect to each specific application.
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Georgieva-Tsaneva G, Gospodinova E, Cheshmedzhiev K. Cardiodiagnostics Based on Photoplethysmographic Signals. Diagnostics (Basel) 2022; 12:diagnostics12020412. [PMID: 35204503 PMCID: PMC8871237 DOI: 10.3390/diagnostics12020412] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/02/2022] [Accepted: 02/03/2022] [Indexed: 11/16/2022] Open
Abstract
The article presents a methodology to support the process of correct cardiodiagnostics based on cardio signals recorded with modern optical photoplethysmographic (PPG) sensor devices. An algorithm for preprocessing registered PPG signals and the formation of a time series for the analysis of heart rate variability is presented, which is an important information indicator in the diagnosis of cardiovascular diseases. In order to validate the proposed algorithm, an experimental scheme for synchronous recordings of PPG and electrocardiographic (ECG) signals and the study of the accuracy of the registered signals was created. The obtained results show high accuracy of the studied signals in terms of the following parameters: number of QRS complexes/pulse waves and mean RR intervals/PP intervals and the finding that the proposed algorithm is suitable for preprocessing PPG signals, as well as the possibility of interchangeable use of PPG and ECG. The results of the mathematical analysis of heart rate variability by applying linear methods (Time-Domain and Frequency-Domain) to two groups of people are presented: healthy controls and patients with cardiovascular disease (syncope). After determining the values of the parameters of the methods used, in order to distinguish healthy subjects from sick ones, statistical analysis was applied using t-test and Receiver Operating Characteristics (ROC) analysis. The obtained results show that the linear methods used are suitable for analysing the dynamics of PP interval series and for distinguishing healthy subjects from those with pathological diseases. The presented research and analyses can find applications in guaranteeing correctness and accuracy of conducting cardiodiagnostics in clinical practice.
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Davies HJ, Bachtiger P, Williams I, Molyneaux PL, Peters NS, Mandic DP. Wearable In-Ear PPG: Detailed Respiratory Variations Enable Classification of COPD. IEEE Trans Biomed Eng 2022; 69:2390-2400. [PMID: 35077352 DOI: 10.1109/tbme.2022.3145688] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
An ability to extract detailed spirometry-like breath-ing waveforms from wearable sensors promises to greatly improve respiratory health monitoring. Photoplethysmography (PPG) has been researched in depth for estimation of respiration rate, given that it varies with respiration through overall intensity, pulse amplitude and pulse interval. We compare and contrast the extraction of these three respiratory modes from both the ear canal and finger and show a marked improvement in the respiratory power for respiration induced intensity variations and pulse amplitude variations when recording from the ear canal. We next employ a data driven multi-scale method, noise assisted multivariate empirical mode decomposition (NA-MEMD), which allows for simultaneous analysis of all three respiratory modes to extract detailed respiratory waveforms from in-ear PPG. For rigour, we considered in-ear PPG recordings from healthy subjects, both older and young, patients with chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF) and healthy subjects with artificially obstructed breathing. Specific in-ear PPG waveform changes are observed for COPD, such as a decreased inspiratory duty cycle and an increased inspiratory magnitude, when compared with expiratory magnitude. These differences are used to classify COPD from healthy and IPF waveforms with a sensitivity of 87% and an overall accuracy of 92%. Our findings indicate the promise of in-ear PPG for COPD screening and unobtrusive respiratory monitoring in ambulatory scenarios and in consumer wearables.
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Haveman ME, van Rossum MC, Vaseur RME, van der Riet C, Schuurmann RCL, Hermens HJ, de Vries JPPM, Tabak M. Continuous Monitoring of Vital Signs With Wearable Sensors During Daily Life Activities: Validation Study. JMIR Form Res 2022; 6:e30863. [PMID: 34994703 PMCID: PMC8783291 DOI: 10.2196/30863] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 09/17/2021] [Accepted: 10/05/2021] [Indexed: 01/19/2023] Open
Abstract
Background Continuous telemonitoring of vital signs in a clinical or home setting may lead to improved knowledge of patients’ baseline vital signs and earlier detection of patient deterioration, and it may also facilitate the migration of care toward home. Little is known about the performance of available wearable sensors, especially during daily life activities, although accurate technology is critical for clinical decision-making. Objective The aim of this study is to assess the data availability, accuracy, and concurrent validity of vital sign data measured with wearable sensors in volunteers during various daily life activities in a simulated free-living environment. Methods Volunteers were equipped with 4 wearable sensors (Everion placed on the left and right arms, VitalPatch, and Fitbit Charge 3) and 2 reference devices (Oxycon Mobile and iButton) to obtain continuous measurements of heart rate (HR), respiratory rate (RR), oxygen saturation (SpO2), and temperature. Participants performed standardized activities, including resting, walking, metronome breathing, chores, stationary cycling, and recovery afterward. Data availability was measured as the percentage of missing data. Accuracy was evaluated by the median absolute percentage error (MAPE) and concurrent validity using the Bland-Altman plot with mean difference and 95% limits of agreement (LoA). Results A total of 20 volunteers (median age 64 years, range 20-74 years) were included. Data availability was high for all vital signs measured by VitalPatch and for HR and temperature measured by Everion. Data availability for HR was the lowest for Fitbit (4807/13,680, 35.14% missing data points). For SpO2 measured by Everion, median percentages of missing data of up to 100% were noted. The overall accuracy of HR was high for all wearable sensors, except during walking. For RR, an overall MAPE of 8.6% was noted for VitalPatch and that of 18.9% for Everion, with a higher MAPE noted during physical activity (up to 27.1%) for both sensors. The accuracy of temperature was high for VitalPatch (MAPE up to 1.7%), and it decreased for Everion (MAPE from 6.3% to 9%). Bland-Altman analyses showed small mean differences of VitalPatch for HR (0.1 beats/min [bpm]), RR (−0.1 breaths/min), and temperature (0.5 °C). Everion and Fitbit underestimated HR up to 5.3 (LoA of −39.0 to 28.3) bpm and 11.4 (LoA of −53.8 to 30.9) bpm, respectively. Everion had a small mean difference with large LoA (−10.8 to 10.4 breaths/min) for RR, underestimated SpO2 (>1%), and overestimated temperature up to 2.9 °C. Conclusions Data availability, accuracy, and concurrent validity of the studied wearable sensors varied and differed according to activity. In this study, the accuracy of all sensors decreased with physical activity. Of the tested sensors, VitalPatch was found to be the most accurate and valid for vital signs monitoring.
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Affiliation(s)
- Marjolein E Haveman
- Department of Surgery, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Mathilde C van Rossum
- Department of Biomedical Signals and Systems, University of Twente, Enschede, Netherlands.,Department of Cardiovascular and Respiratory Physiology, University of Twente, Enschede, Netherlands
| | - Roswita M E Vaseur
- Department of Biomedical Signals and Systems, University of Twente, Enschede, Netherlands
| | - Claire van der Riet
- Department of Surgery, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Richte C L Schuurmann
- Department of Surgery, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Hermie J Hermens
- Department of Biomedical Signals and Systems, University of Twente, Enschede, Netherlands.,eHealth group, Roessingh Research and Development, Enschede, Netherlands
| | - Jean-Paul P M de Vries
- Department of Surgery, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Monique Tabak
- Department of Biomedical Signals and Systems, University of Twente, Enschede, Netherlands.,eHealth group, Roessingh Research and Development, Enschede, Netherlands
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Haveman ME, van Melzen R, Schuurmann RCL, El Moumni M, Hermens HJ, Tabak M, de Vries JPPM. Continuous monitoring of vital signs with the Everion biosensor on the surgical ward: a clinical validation study. Expert Rev Med Devices 2021; 18:145-152. [PMID: 34937478 DOI: 10.1080/17434440.2021.2019014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
BACKGROUND Wearable sensors enable continuous vital sign monitoring, although information about their performance on nursing wards is scarce. Vital signs measured by telemonitoring and nurse measurements on a surgical ward were compared to assess validity and reliability. METHODS In a prospective observational study, surgical patients wore a wearable sensor (Everion, Biovotion AG, Zürich, Switzerland) that continuously measured heart rate (HR), respiratory rate (RR), oxygen saturation (SpO2), and temperature during their admittance on the ward. Validity was evaluated using repeated-measures correlation and reliability using Bland-Altman plots, mean difference, and 95% limits of agreement (LoA). RESULTS Validity analyses of 19 patients (median age, 68; interquartile range, 62.5-72.5 years) showed a moderate relationship between telemonitoring and nurse measurements for HR (r = 0.53; 95% confidence interval, 0.44-0.61) and a poor relationship for RR, SpO2, and temperature. Reliability analyses showed that Everion measured HR close to nurse measurements (mean difference, 1 bpm; LoA, -16.7 to 18.7 bpm). Everion overestimated RR at higher values, whereas SpO2 and temperature were underestimated. CONCLUSIONS A moderate relationship was determined between Everion and nurse measurements at a surgical ward in this study. Validity and reliability of telemonitoring should also be assessed with gold standard devices in future clinical trials.
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Affiliation(s)
- Marjolein E Haveman
- Department of Surgery, Division of Vascular Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Rianne van Melzen
- Department of Surgery, Division of Vascular Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.,Department of Surgery, Division of Trauma Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Richte C L Schuurmann
- Department of Surgery, Division of Vascular Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Mostafa El Moumni
- Department of Surgery, Division of Trauma Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Hermie J Hermens
- Department of Biomedical Signals and Systems, University of Twente, Enschede, The Netherlands.,eHealth Group, Roessingh Research and Development, Enschede, The Netherlands
| | - Monique Tabak
- Department of Biomedical Signals and Systems, University of Twente, Enschede, The Netherlands.,eHealth Group, Roessingh Research and Development, Enschede, The Netherlands
| | - Jean-Paul P M de Vries
- Department of Surgery, Division of Vascular Surgery, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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Lin Q, Song S, Van Wegberg R, Sijbers W, Biswas D, Konijnenburg M, Van Hoof C, Tavernier F, Van Helleputte N. A 134 DB Dynamic Range Noise Shaping Slope Light-to-Digital Converter for Wearable Chest PPG Applications. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2021; 15:1224-1235. [PMID: 34818192 DOI: 10.1109/tbcas.2021.3130470] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
This paper presents a low power, high dynamic range (DR), light-to-digital converter (LDC) for wearable chest photoplethysmogram (PPG) applications. The proposed LDC utilizes a novel 2nd-order noise-shaping slope architecture, directly converting the photocurrent to a digital code. This LDC applies a high-resolution dual-slope quantizer for data conversion. An auxiliary noise shaping loop is used to shape the residual quantization noise. Moreover, a DC compensation loop is implemented to cancel the PPG signal's DC component, thus further boosting the DR. The prototype is fabricated with 0.18 μm standard CMOS and characterized experimentally. The LDC consumes 28 μW per readout channel while achieving a maximum 134 dB DR. The LDC is also validated with on-body chest PPG measurement.
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Antali F, Kulin D, Lucz KI, Szabó B, Szűcs L, Kulin S, Miklós Z. Multimodal Assessment of the Pulse Rate Variability Analysis Module of a Photoplethysmography-Based Telemedicine System. SENSORS 2021; 21:s21165544. [PMID: 34450986 PMCID: PMC8401087 DOI: 10.3390/s21165544] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/06/2021] [Accepted: 08/14/2021] [Indexed: 12/25/2022]
Abstract
Alterations of heart rate variability (HRV) are associated with various (patho)physiological conditions; therefore, HRV analysis has the potential to become a useful diagnostic module of wearable/telemedical devices to support remote cardiovascular/autonomic monitoring. Continuous pulse recordings obtained by photoplethysmography (PPG) can yield pulse rate variability (PRV) indices similar to HRV parameters; however, it is debated whether PRV/HRV parameters are interchangeable. In this study, we assessed the PRV analysis module of a digital arterial PPG-based telemedical system (SCN4ALL). We used Bland–Altman analysis to validate the SCN4ALL PRV algorithm to Kubios Premium software and to determine the agreements between PRV/HRV results calculated from 2-min long PPG and ECG captures recorded simultaneously in healthy individuals (n = 33) at rest and during the cold pressor test, and in diabetic patients (n = 12) at rest. We found an ideal agreement between SCN4ALL and Kubios outputs (bias < 2%). PRV and HRV parameters showed good agreements for interbeat intervals, SDNN, and RMSSD time-domain variables, for total spectral and low-frequency power (LF) frequency-domain variables, and for non-linear parameters in healthy subjects at rest and during cold pressor challenge. In diabetics, good agreements were observed for SDNN, LF, and SD2; and moderate agreement was observed for total power. In conclusion, the SCN4ALL PRV analysis module is a good alternative for HRV analysis for numerous conventional HRV parameters.
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Affiliation(s)
- Flóra Antali
- Institute of Translational Medicine, Semmelweis University, 1094 Budapest, Hungary;
- E-Med4All Europe Ltd., 1036 Budapest, Hungary; (K.I.L.); (B.S.); (L.S.); (S.K.)
- Correspondence: (F.A.); (Z.M.); Tel.: +36-70-323-7431 (F.A.); +36-20-585-8099 (Z.M.)
| | - Dániel Kulin
- Institute of Translational Medicine, Semmelweis University, 1094 Budapest, Hungary;
- E-Med4All Europe Ltd., 1036 Budapest, Hungary; (K.I.L.); (B.S.); (L.S.); (S.K.)
| | - Konrád István Lucz
- E-Med4All Europe Ltd., 1036 Budapest, Hungary; (K.I.L.); (B.S.); (L.S.); (S.K.)
| | - Balázs Szabó
- E-Med4All Europe Ltd., 1036 Budapest, Hungary; (K.I.L.); (B.S.); (L.S.); (S.K.)
| | - László Szűcs
- E-Med4All Europe Ltd., 1036 Budapest, Hungary; (K.I.L.); (B.S.); (L.S.); (S.K.)
- Antal Bejczy Center for Intelligent Robotics, Óbuda University, 1034 Budapest, Hungary
| | - Sándor Kulin
- E-Med4All Europe Ltd., 1036 Budapest, Hungary; (K.I.L.); (B.S.); (L.S.); (S.K.)
| | - Zsuzsanna Miklós
- Institute of Translational Medicine, Semmelweis University, 1094 Budapest, Hungary;
- Correspondence: (F.A.); (Z.M.); Tel.: +36-70-323-7431 (F.A.); +36-20-585-8099 (Z.M.)
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Fine J, Branan KL, Rodriguez AJ, Boonya-ananta T, Ajmal, Ramella-Roman JC, McShane MJ, Coté GL. Sources of Inaccuracy in Photoplethysmography for Continuous Cardiovascular Monitoring. BIOSENSORS 2021; 11:126. [PMID: 33923469 PMCID: PMC8073123 DOI: 10.3390/bios11040126] [Citation(s) in RCA: 91] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 03/30/2021] [Accepted: 04/09/2021] [Indexed: 12/14/2022]
Abstract
Photoplethysmography (PPG) is a low-cost, noninvasive optical technique that uses change in light transmission with changes in blood volume within tissue to provide information for cardiovascular health and fitness. As remote health and wearable medical devices become more prevalent, PPG devices are being developed as part of wearable systems to monitor parameters such as heart rate (HR) that do not require complex analysis of the PPG waveform. However, complex analyses of the PPG waveform yield valuable clinical information, such as: blood pressure, respiratory information, sympathetic nervous system activity, and heart rate variability. Systems aiming to derive such complex parameters do not always account for realistic sources of noise, as testing is performed within controlled parameter spaces. A wearable monitoring tool to be used beyond fitness and heart rate must account for noise sources originating from individual patient variations (e.g., skin tone, obesity, age, and gender), physiology (e.g., respiration, venous pulsation, body site of measurement, and body temperature), and external perturbations of the device itself (e.g., motion artifact, ambient light, and applied pressure to the skin). Here, we present a comprehensive review of the literature that aims to summarize these noise sources for future PPG device development for use in health monitoring.
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Affiliation(s)
- Jesse Fine
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA; (J.F.); (K.L.B.)
| | - Kimberly L. Branan
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA; (J.F.); (K.L.B.)
| | - Andres J. Rodriguez
- Department of Biomedical Engineering, Florida International University, Miami, FL 33174, USA; (A.J.R.); (T.B.-a.); (A.); (J.C.R.-R.)
| | - Tananant Boonya-ananta
- Department of Biomedical Engineering, Florida International University, Miami, FL 33174, USA; (A.J.R.); (T.B.-a.); (A.); (J.C.R.-R.)
| | - Ajmal
- Department of Biomedical Engineering, Florida International University, Miami, FL 33174, USA; (A.J.R.); (T.B.-a.); (A.); (J.C.R.-R.)
| | - Jessica C. Ramella-Roman
- Department of Biomedical Engineering, Florida International University, Miami, FL 33174, USA; (A.J.R.); (T.B.-a.); (A.); (J.C.R.-R.)
- Herbert Wertheim College of Medicine, Florida International University, Miami, FL 33199, USA
| | - Michael J. McShane
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA; (J.F.); (K.L.B.)
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, USA
- Center for Remote Health Technologies and Systems, Texas A&M Engineering Experimentation Station, Texas A&M University, College Station, TX 77843, USA
| | - Gerard L. Coté
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843, USA; (J.F.); (K.L.B.)
- Center for Remote Health Technologies and Systems, Texas A&M Engineering Experimentation Station, Texas A&M University, College Station, TX 77843, USA
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Nabavi S, Debbarma S, Bhadra S. A Smart Mandibular Advancement Device for Intraoral Cardiorespiratory Monitoring. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:4079-4084. [PMID: 33018895 DOI: 10.1109/embc44109.2020.9176520] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We propose a smart mandibular advancement device (MAD) that can monitor cardiorespiratory parameters intraorally. The device comprises a flexible hybrid wireless monitoring platform integrated with a MAD. This monitoring platform is based on acquiring the intraoral photoplethysmography (PPG) signals. It is designed on a double-sided flexible polyimide substrate. Our experimental measurements show that the PPG signals captured intraorally are highly correlated with the conventional PPG signals received from the fingertip. Intraoral PPG signals have vital information as well as adequate quality to be utilized for estimation of multiple-physiological parameters, such as heart-rate (HR), respiration rate (RR), respiration pattern (RP) and blood oxygen saturation (SpO2). The estimated values of HR, RR, and SpO2 from the intraoral PPG signals recorded by our smart MAD show an accuracy of over 96% with reference to the conventional monitoring techniques.
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14
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Liu H, Chen F, Hartmann V, Khalid SG, Hughes S, Zheng D. Comparison of different modulations of photoplethysmography in extracting respiratory rate: from a physiological perspective. Physiol Meas 2020; 41:094001. [DOI: 10.1088/1361-6579/abaaf0] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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15
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Davies HJ, Williams I, Peters NS, Mandic DP. In-Ear SpO 2: A Tool for Wearable, Unobtrusive Monitoring of Core Blood Oxygen Saturation. SENSORS (BASEL, SWITZERLAND) 2020; 20:E4879. [PMID: 32872310 PMCID: PMC7506719 DOI: 10.3390/s20174879] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 08/24/2020] [Accepted: 08/24/2020] [Indexed: 02/06/2023]
Abstract
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.
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Affiliation(s)
- Harry J. Davies
- Department of Electrical and Electronic Engineering, Imperial College London, London SW7 2AZ, UK; (I.W.); (D.P.M.)
- Imperial Centre for Cardiac Engineering, Imperial College London, London SW7 2AZ, UK;
| | - Ian Williams
- Department of Electrical and Electronic Engineering, Imperial College London, London SW7 2AZ, UK; (I.W.); (D.P.M.)
- Imperial Centre for Cardiac Engineering, Imperial College London, London SW7 2AZ, UK;
| | - Nicholas S. Peters
- Imperial Centre for Cardiac Engineering, Imperial College London, London SW7 2AZ, UK;
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London SW3 6LY, UK
| | - Danilo P. Mandic
- Department of Electrical and Electronic Engineering, Imperial College London, London SW7 2AZ, UK; (I.W.); (D.P.M.)
- Imperial Centre for Cardiac Engineering, Imperial College London, London SW7 2AZ, UK;
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16
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Kwon S, Hong J, Choi EK, Lee B, Baik C, Lee E, Jeong ER, Koo BK, Oh S, Yi Y. Detection of Atrial Fibrillation Using a Ring-Type Wearable Device (CardioTracker) and Deep Learning Analysis of Photoplethysmography Signals: Prospective Observational Proof-of-Concept Study. J Med Internet Res 2020; 22:e16443. [PMID: 32348254 PMCID: PMC7273241 DOI: 10.2196/16443] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 02/24/2020] [Accepted: 03/21/2020] [Indexed: 12/23/2022] Open
Abstract
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
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Affiliation(s)
- Soonil Kwon
- Seoul National University Hospital, Seoul, Republic of Korea
| | - Joonki Hong
- Department of Electrical Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Eue-Keun Choi
- Seoul National University Hospital, Seoul, Republic of Korea
| | | | | | - Euijae Lee
- Seoul National University Hospital, Seoul, Republic of Korea
| | - Eui-Rim Jeong
- Department of Information and Communication Engineering, Hanbat National University, Daejeon, Republic of Korea
| | - Bon-Kwon Koo
- Seoul National University Hospital, Seoul, Republic of Korea
| | - Seil Oh
- Seoul National University Hospital, Seoul, Republic of Korea
| | - Yung Yi
- Department of Electrical Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
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Investigation of Photoplethysmography Behind the Ear for Pulse Oximetry in Hypoxic Conditions with a Novel Device (SPYDR). BIOSENSORS-BASEL 2020; 10:bios10040034. [PMID: 32260393 PMCID: PMC7235881 DOI: 10.3390/bios10040034] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 04/01/2020] [Accepted: 04/02/2020] [Indexed: 11/30/2022]
Abstract
Photoplethysmography (PPG) is a valuable technique for noninvasively evaluating physiological parameters. However, traditional PPG devices have significant limitations in high-motion and low-perfusion environments. To overcome these limitations, we investigated the accuracy of a clinically novel PPG site using SPYDR®, a new PPG sensor suite, against arterial blood gas (ABG) measurements as well as other commercial PPG sensors at the finger and forehead in hypoxic environments. SPYDR utilizes a reflectance PPG sensor applied behind the ear, between the pinna and the hairline, on the mastoid process, above the sternocleidomastoid muscle, near the posterior auricular artery in a self-contained ear cup system. ABG revealed accuracy of SPYDR with a root mean square error of 2.61% at a 70–100% range, meeting FDA requirements for PPG sensor accuracy. Subjects were also instrumented with SPYDR, as well as finger and forehead PPG sensors, and pulse rate (PR) and oxygen saturation (SpO2) were measured and compared at various reduced oxygen profiles with a reduced oxygen breathing device (ROBD). SPYDR was shown to be as accurate as other sensors in reduced oxygen environments with a Pearson’s correlation >93% for PR and SpO2. In addition, SPYDR responded to changes in SpO2 up to 50 s faster than PPG measurements at the finger and forehead.
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18
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Yuda E, Yamamoto K, Yoshida Y, Hayano J. Differences in pulse rate variability with measurement site. J Physiol Anthropol 2020; 39:4. [PMID: 32085811 PMCID: PMC7035641 DOI: 10.1186/s40101-020-0214-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 02/13/2020] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Recently, attempts have been made to use the pulse rate variability (PRV) as a surrogate for heart rate variability (HRV). PRV, however, may be caused by the fluctuations of left ventricular pre-ejection period and pulse transit time besides HRV. We examined whether PRV differs not only from HRV but also depending on the measurement site. RESULTS In five healthy subjects, pulse waves were measured simultaneously on both wrists and both forearms together with single-lead electrocardiogram (ECG) in the supine and sitting positions. Although average pulse interval showed no significant difference from average R-R interval in either positions, PRV showed greater power for the low-frequency (LF) and high-frequency (HF) components and lower LF/HF than HRV. The deviations of PRV from HRV in the supine and sitting positions were 13.2% and 7.9% for LF power, 24.5% and 18.3% for HF power, and - 15.0% and - 30.2% for LF/HF, respectively. While the average pulse interval showed 0.8% and 0.5% inter-site variations among the four sites in the supine and sitting positions, respectively, the inter-site variations in PRV were 4.0% and 3.6% for LF power, 3.8% and 4.7% for HF power, and 18.0% and 17.5% for LF/HF, respectively. CONCLUSIONS These suggest that PRV shows not only systemic differences from HRV but also considerable inter-site variations.
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Affiliation(s)
- Emi Yuda
- Tohoku University Graduate School of Engineering, Aoba 6-6-05 Aramaki Aoba-ku, Sendai, 980-8759 Japan
| | - Kento Yamamoto
- University of Tsukuba Graduate School of Comprehensive Human Sciences, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577 Japan
| | - Yutaka Yoshida
- Nagoya City University Graduate School of Design and Architecture, Kita Chikusa 2-1-10 Chikusa-ku, Nagoya, 464-0083 Japan
| | - Junichiro Hayano
- Department of Medical Education, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi Mizuho-cho Mizuho-ku, Nagoya, 467-8601 Japan
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Han CH, Kim E, Im CH. Development of a Brain-Computer Interface Toggle Switch with Low False-Positive Rate Using Respiration-Modulated Photoplethysmography. SENSORS (BASEL, SWITZERLAND) 2020; 20:E348. [PMID: 31936250 PMCID: PMC7013717 DOI: 10.3390/s20020348] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 01/01/2020] [Accepted: 01/07/2020] [Indexed: 12/13/2022]
Abstract
Asynchronous brain-computer interfaces (BCIs) based on electroencephalography (EEG) generally suffer from poor performance in terms of classification accuracy and false-positive rate (FPR). Thus, BCI toggle switches based on electrooculogram (EOG) signals were developed to toggle on/off synchronous BCI systems. The conventional BCI toggle switches exhibit fast responses with high accuracy; however, they have a high FPR or cannot be applied to patients with oculomotor impairments. To circumvent these issues, we developed a novel BCI toggle switch that users can employ to toggle on or off synchronous BCIs by holding their breath for a few seconds. Two states-normal breath and breath holding-were classified using a linear discriminant analysis with features extracted from the respiration-modulated photoplethysmography (PPG) signals. A real-time BCI toggle switch was implemented with calibration data trained with only 1-min PPG data. We evaluated the performance of our PPG switch by combining it with a steady-state visual evoked potential-based BCI system that was designed to control four external devices, with regard to the true-positive rate and FPR. The parameters of the PPG switch were optimized through an offline experiment with five subjects, and the performance of the switch system was evaluated in an online experiment with seven subjects. All the participants successfully turned on the BCI by holding their breath for approximately 10 s (100% accuracy), and the switch system exhibited a very low FPR of 0.02 false operations per minute, which is the lowest FPR reported thus far. All participants could successfully control external devices in the synchronous BCI mode. Our results demonstrated that the proposed PPG-based BCI toggle switch can be used to implement practical BCIs.
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Affiliation(s)
| | | | - Chang-Hwan Im
- Department of Biomedical Engineering, Hanyang University, Seoul 04763, Korea; (C.-H.H.); (E.K.)
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20
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Hernando A, Peláez-Coca MD, Lozano MT, Lázaro J, Gil E. Finger and forehead PPG signal comparison for respiratory rate estimation. Physiol Meas 2019; 40:095007. [DOI: 10.1088/1361-6579/ab3be0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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21
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Allen J. Quantifying the Delays Between Multi-Site Photoplethysmography Pulse and Electrocardiogram R-R Interval Changes Under Slow-Paced Breathing. Front Physiol 2019; 10:1190. [PMID: 31607946 PMCID: PMC6774289 DOI: 10.3389/fphys.2019.01190] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 09/03/2019] [Indexed: 12/05/2022] Open
Abstract
Objective: Objective assessment of autonomic function is important, including the investigation of slow-paced breathing to induce associated periodic changes in the cardiovascular system – such as blood pressure and heart rate. However, pulse changes across a range of peripheral body sites have seldom been explored with this challenge. The primary aim of this pilot study was to utilize multi-site photoplethysmography (MPPG) technology to quantify the phase delays, i.e., correlation lags, between changes in heart rate and changes in key pulse features with slow-paced breathing (0.1 Hz). Methods: Waveforms were collected simultaneously from the right and left ear lobes, thumbs, and great toes of 18 healthy adult subjects. Cross correlation lags between reference beat-to-beat changes in electrocardiogram (ECG) R-R wave interval and changes in pulse arrival time (foot of pulse; PATf) and also for pulse amplitude (foot-to-peak; AMP) were determined. Results: Relative to R-R changes, the median ear, thumb, and toe PATf correlation lags were 3.4, 2.9, and 2.1 beats, respectively; contrasting to AMP with 5.7, 6.0, and 6.9 beats, respectively. These PATf correlation lags in beats were significantly lower than for the AMP measure. Segmental differences between sites and timing measure variability have also been quantified. Conclusion: This pilot study has indicated bilateral similarity plus segmental differences for relative delays in PPG pulse timing and amplitude measures relative to R-R interval changes with paced breathing. These correlation and variability data are now available for comparison with cardiovascular patient groups to support development of autonomic function assessment techniques.
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Affiliation(s)
- John Allen
- Microvascular Diagnostics, Northern Medical Physics and Clinical Engineering Department, Freeman Hospital, Newcastle upon Tyne, United Kingdom.,Faculty of Medical Sciences, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
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22
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Liu H, Allen J, Zheng D, Chen F. Recent development of respiratory rate measurement technologies. Physiol Meas 2019; 40:07TR01. [PMID: 31195383 DOI: 10.1088/1361-6579/ab299e] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Respiratory rate (RR) is an important physiological parameter whose abnormality has been regarded as an important indicator of serious illness. In order to make RR monitoring simple to perform, reliable and accurate, many different methods have been proposed for such automatic monitoring. According to the theory of respiratory rate extraction, methods are categorized into three modalities: extracting RR from other physiological signals, RR measurement based on respiratory movements, and RR measurement based on airflow. The merits and limitations of each method are highlighted and discussed. In addition, current works are summarized to suggest key directions for the development of future RR monitoring methodologies.
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Affiliation(s)
- Haipeng Liu
- Faculty of Health, Education, Medicine, and Social Care, Anglia Ruskin University, Chelmsford, CM1 1SQ, United Kingdom. Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
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23
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A Comparison of Reflective Photoplethysmography for Detection of Heart Rate, Blood Oxygen Saturation, and Respiration Rate at Various Anatomical Locations. SENSORS 2019; 19:s19081874. [PMID: 31010184 PMCID: PMC6514840 DOI: 10.3390/s19081874] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 04/14/2019] [Accepted: 04/17/2019] [Indexed: 01/30/2023]
Abstract
Monitoring of vital signs is critical for patient triage and management. Principal assessments of patient conditions include respiratory rate heart/pulse rate and blood oxygen saturation. However, these assessments are usually carried out with multiple sensors placed in different body locations. The aim of this paper is to identify a single location on the human anatomy whereby a single 1 cm × 1 cm non-invasive sensor could simultaneously measure heart rate (HR), blood oxygen saturation (SpO2), and respiration rate (RR), at rest and while walking. To evaluate the best anatomical location, we analytically compared eight anatomical locations for photoplethysmography (PPG) sensors simultaneously acquired by a single microprocessor at rest and while walking, with a comparison to a commercial pulse oximeter and respiration rate ground truth. Our results show that the forehead produced the most accurate results for HR and SpO2 both at rest and walking, however, it had poor RR results. The finger recorded similar results for HR and SpO2, however, it had more accurate RR results. Overall, we found the finger to be the best location for measurement of all three parameters at rest; however, no site was identified as capable of measuring all parameters while walking.
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Hartmann V, Liu H, Chen F, Qiu Q, Hughes S, Zheng D. Quantitative Comparison of Photoplethysmographic Waveform Characteristics: Effect of Measurement Site. Front Physiol 2019; 10:198. [PMID: 30890959 PMCID: PMC6412091 DOI: 10.3389/fphys.2019.00198] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 02/15/2019] [Indexed: 11/13/2022] Open
Abstract
Introduction: Photoplethysmography (PPG) has been widely used to assess cardiovascular function. However, few studies have comprehensively investigated the effect of measurement site on PPG waveform characteristics. This study aimed to provide a quantitative comparison on this. Methods: Thirty six healthy subjects participated in this study. For each subject, PPG signals were sequentially recorded for 1 min from six different body sites (finger, wrist under (anatomically volar), wrist upper (dorsal), arm, earlobe, and forehead) under both normal and deep breathing patterns. For each body site under a certain breathing pattern, the mean amplitude was firstly derived from recorded PPG waveform which was then normalized to derive several waveform characteristics including the pulse peak time (Tp), dicrotic notch time (Tn), and the reflection index (RI). The effects of breathing pattern and measurement site on the waveform characteristics were finally investigated by the analysis of variance (ANOVA) with post hoc multiple comparisons. Results: Under both breathing patterns, the PPG measurements from the finger achieved the highest percentage of analyzable waveforms for extracting waveform characteristics. There were significant effects of breathing pattern on Tn and RI (larger Tn and smaller RI with deep breathing on average, both p < 0.03). The effects of measurement site on mean amplitude, Tp, Tn, and RI were significant (all p < 0.001). The key results were that, under both breathing patterns, the mean amplitude from finger PPG was significantly larger and its Tp and RI were significantly smaller than those from the other five sites (all p < 0.001, except p = 0.04 for the Tp of "wrist under"), and Tn was only significantly larger than that from the earlobe (both p < 0.05). Conclusion: This study has quantitatively confirmed the effect of PPG measurement site on PPG waveform characteristics (including mean amplitude, Tp, Tn, and RI), providing scientific evidence for a better understanding of the PPG waveform variations between different body sites.
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Affiliation(s)
- Vera Hartmann
- Faculty of Health, Education, Medicine and Social Care, Anglia Ruskin University, Chelmsford, United Kingdom
| | - Haipeng Liu
- Faculty of Health, Education, Medicine and Social Care, Anglia Ruskin University, Chelmsford, United Kingdom.,Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Fei Chen
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Qian Qiu
- Faculty of Health, Education, Medicine and Social Care, Anglia Ruskin University, Chelmsford, United Kingdom
| | - Stephen Hughes
- Faculty of Health, Education, Medicine and Social Care, Anglia Ruskin University, Chelmsford, United Kingdom
| | - Dingchang Zheng
- Faculty of Health, Education, Medicine and Social Care, Anglia Ruskin University, Chelmsford, United Kingdom
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25
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Dur O, Rhoades C, Ng MS, Elsayed R, van Mourik R, Majmudar MD. Design Rationale and Performance Evaluation of the Wavelet Health Wristband: Benchtop Validation of a Wrist-Worn Physiological Signal Recorder. JMIR Mhealth Uhealth 2018; 6:e11040. [PMID: 30327288 PMCID: PMC6231731 DOI: 10.2196/11040] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 08/23/2018] [Accepted: 09/10/2018] [Indexed: 11/23/2022] Open
Abstract
Background Wearable and connected health devices along with the recent advances in mobile and cloud computing provide a continuous, convenient-to-patient, and scalable way to collect personal health data remotely. The Wavelet Health platform and the Wavelet wristband have been developed to capture multiple physiological signals and to derive biometrics from these signals, including resting heart rate (HR), heart rate variability (HRV), and respiration rate (RR). Objective This study aimed to evaluate the accuracy of the biometric estimates and signal quality of the wristband. Methods Measurements collected from 35 subjects using the Wavelet wristband were compared with simultaneously recorded electrocardiogram and spirometry measurements. Results The HR, HRV SD of normal-to-normal intervals, HRV root mean square of successive differences, and RR estimates matched within 0.7 beats per minute (SD 0.9), 7 milliseconds (SD 10), 11 milliseconds (SD 12), and 1 breaths per minute (SD 1) mean absolute deviation of the reference measurements, respectively. The quality of the raw plethysmography signal collected by the wristband, as determined by the harmonic-to-noise ratio, was comparable with that obtained from measurements from a finger-clip plethysmography device. Conclusions The accuracy of the biometric estimates and high signal quality indicate that the wristband photoplethysmography device is suitable for performing pulse wave analysis and measuring vital signs.
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Affiliation(s)
- Onur Dur
- Wavelet Health, Mountain View, CA, United States
| | | | - Man Suen Ng
- Wavelet Health, Mountain View, CA, United States
| | - Ragwa Elsayed
- Biomedical Engineering, San Jose State University, San Jose, CA, United States
| | | | - Maulik D Majmudar
- Healthcare Transformation Lab, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
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Charlton PH, Birrenkott DA, Bonnici T, Pimentel MAF, Johnson AEW, Alastruey J, Tarassenko L, Watkinson PJ, Beale R, Clifton DA. Breathing Rate Estimation From the Electrocardiogram and Photoplethysmogram: A Review. IEEE Rev Biomed Eng 2017; 11:2-20. [PMID: 29990026 PMCID: PMC7612521 DOI: 10.1109/rbme.2017.2763681] [Citation(s) in RCA: 127] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Breathing rate (BR) is a key physiological parameter used in a range of clinical settings. Despite its diagnostic and prognostic value, it is still widely measured by counting breaths manually. A plethora of algorithms have been proposed to estimate BR from the electrocardiogram (ECG) and pulse oximetry (photoplethysmogram, PPG) signals. These BR algorithms provide opportunity for automated, electronic, and unobtrusive measurement of BR in both healthcare and fitness monitoring. This paper presents a review of the literature on BR estimation from the ECG and PPG. First, the structure of BR algorithms and the mathematical techniques used at each stage are described. Second, the experimental methodologies that have been used to assess the performance of BR algorithms are reviewed, and a methodological framework for the assessment of BR algorithms is presented. Third, we outline the most pressing directions for future research, including the steps required to use BR algorithms in wearable sensors, remote video monitoring, and clinical practice.
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Affiliation(s)
- Peter H. Charlton
- Department of Biomedical Engineering, King’s College London, London SE1 7EH, U.K., and also with the Department of Engineering Science, University of Oxford, Oxford OX3 7DQ, U.K
| | - Drew A. Birrenkott
- Department of Engineering Science, University of Oxford, Oxford OX3 7DQ, U.K
| | - Timothy Bonnici
- Nuffield Department of Medicine, University of Oxford, Oxford OX3 9DU, U.K., and also with the Department of Asthma, Allergy, and Lung Biology, King’s College London, London SE1 7EH, U.K
| | | | - Alistair E. W. Johnson
- Laboratory for Computational Physiology, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Jordi Alastruey
- Department of Biomedical Engineering, King’s College London, London SE1 7EH, U.K
| | - Lionel Tarassenko
- Department of Engineering Science, University of Oxford, Oxford OX3 7DQ, U.K
| | - Peter J. Watkinson
- Kadoorie Centre for Critical Care Research and Education, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, U.K
| | - Richard Beale
- Department of Asthma, Allergy and Lung Biology, King’s College London, London SE1 7EH, U.K
| | - David A. Clifton
- Department of Engineering Science, University of Oxford, Oxford OX3 7DQ, U.K
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Touw HRW, Verheul MH, Tuinman PR, Smit J, Thöne D, Schober P, Boer C. Photoplethysmography respiratory rate monitoring in patients receiving procedural sedation and analgesia for upper gastrointestinal endoscopy. J Clin Monit Comput 2017; 31:747-754. [PMID: 27236561 PMCID: PMC5500676 DOI: 10.1007/s10877-016-9890-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Accepted: 05/20/2016] [Indexed: 02/07/2023]
Abstract
The value of capnography during procedural sedation and analgesia (PSA) for the detection of hypoxaemia during upper gastrointestinal (UGI) endoscopic procedures is limited. Photoplethysmography respiratory rate (RRp) monitoring may provide a useful alternative, but the level of agreement with capnography during PSA is unknown. We therefore investigated the level of agreement between the RRp and capnography-based RR (RRc) during PSA for UGI endoscopy. This study included patients undergoing PSA for UGI endoscopy procedures. Pulse oximetry (SpO2) and RRc were recorded in combination with Nellcor 2.0 (RRp) monitoring (Covidien, USA). Bland-Altman analysis was used to evaluate the level of agreement between RRc and RRp. Episodes of apnoea, defined as no detection of exhaled CO2 for minimal 36 s, and hypoxaemia, defined as an SpO2 < 92 %, were registered. A total of 1054 min of data from 26 patients were analysed. Bland-Altman analysis between the RRc and RRp revealed a bias of 2.25 ± 5.41 breath rate per minute (brpm), with limits of agreement from -8.35 to 12.84 brpm for an RR ≥ 4 brpm. A total of 67 apnoea events were detected. In 21 % of all apnoea events, the patient became hypoxaemic. Hypoxaemia occurred 42 times with a median length of 34 (19-141) s, and was preceded in 34 % of the cases by apnoea and in 64 % by an RRc ≥ 8 brpm. In 81 % of all apnoea events, photoplethysmography registered an RRp ≥ 4 brpm. We found a low level of agreement between capnography and the plethysmography respiratory rate during procedural sedation for UGI endoscopy. Moreover, respiratory rate derived from both the capnogram and photoplethysmogram showed a limited ability to provide warning signs for a hypoxaemic event during the sedation procedure.
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Affiliation(s)
- Hugo R W Touw
- Department of Anaesthesiology, Institute for Cardiovascular Research, VU University Medical Centre, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands
| | - Milou H Verheul
- Department of Anaesthesiology, Institute for Cardiovascular Research, VU University Medical Centre, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands
| | - Pieter R Tuinman
- Department of Intensive Care Medicine, Institute for Cardiovascular Research, VU University Medical Centre, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands
| | - Jeroen Smit
- Department of Anaesthesiology, Institute for Cardiovascular Research, VU University Medical Centre, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands
| | - Deirdre Thöne
- Department of Anaesthesiology, Institute for Cardiovascular Research, VU University Medical Centre, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands
| | - Patrick Schober
- Department of Anaesthesiology, Institute for Cardiovascular Research, VU University Medical Centre, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands
| | - Christa Boer
- Department of Anaesthesiology, Institute for Cardiovascular Research, VU University Medical Centre, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands.
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Abay TY, Kyriacou PA. Photoplethysmography for blood volumes and oxygenation changes during intermittent vascular occlusions. J Clin Monit Comput 2017; 32:447-455. [PMID: 28547651 PMCID: PMC5943414 DOI: 10.1007/s10877-017-0030-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 05/19/2017] [Indexed: 12/18/2022]
Abstract
Photoplethysmography (PPG) is an optical technique that measures blood volume variations. The main application of dual-wavelength PPG is pulse oximetry, in which the arterial oxygen saturation (SpO\documentclass[12pt]{minimal}
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\begin{document}$$_2$$\end{document}2) is calculated noninvasively. However, the PPG waveform contains other significant physiological information that can be used in conjunction to SpO\documentclass[12pt]{minimal}
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\begin{document}$$_2$$\end{document}2 for the assessment of oxygenation and blood volumes changes. This paper investigates the use of near infrared spectroscopy (NIRS) processing techniques for extracting relative concentration changes of oxygenated (\documentclass[12pt]{minimal}
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\begin{document}$$\Delta$$\end{document}ΔtHb) from dual-wavelength PPG signals during intermittent pressure-increasing vascular occlusions. A reflectance PPG sensor was attached on the left forearm of nineteen (n = 19) volunteers, along with a reference NIRS sensor positioned on the same forearm, above the left brachioradialis. The investigation protocol consisted of seven intermittent and pressure-increasing vascular occlusions. Relative changes in haemoglobin concentrations were obtained by applying the modified Beer–Lambert law to PPG signals, while oxygenation changes were estimated by the difference between red and infrared attenuations of DC PPGs (A\documentclass[12pt]{minimal}
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\begin{document}$$_{Ox}$$\end{document}Ox = \documentclass[12pt]{minimal}
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\begin{document}$$_{IR}$$\end{document}IR − \documentclass[12pt]{minimal}
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\begin{document}$$_R$$\end{document}R) and by the conventional SpO\documentclass[12pt]{minimal}
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\begin{document}$$_2$$\end{document}2. The \documentclass[12pt]{minimal}
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\begin{document}$$\Delta$$\end{document}ΔtHb from the PPG signals indicated significant changes in perfusion induced by either partial and complete occlusions (p < 0.05). The trends in the variables extracted from PPG showed good correlation with the same parameters measured by the reference NIRS monitor. Bland and Altman analysis of agreement between PPG and NIRS showed underestimation of the magnitude of changes by the PPG. A\documentclass[12pt]{minimal}
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\begin{document}$$_{Ox}$$\end{document}Ox indicated significant changes for occlusion pressures exceeding 20 mmHg (p < 0.05) and correlation with tissue oxygenation changes measured by NIRS, while SpO\documentclass[12pt]{minimal}
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\begin{document}$$_2$$\end{document}2 had significant changes after 40 mmHg (p < 0.05). Relative changes in haemoglobin concentrations can be estimated from PPG signals and they showed a good level of accuracy in the detection of perfusion and oxygenation changes induced by different degrees of intermittent vascular occlusions. These results can open up to new applications of the PPG waveform in the detection of blood volumes and oxygenation changes.
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Affiliation(s)
- T Y Abay
- School of Mathematics, Computer Sciences and Engineering, City, University of London, London, UK.
| | - P A Kyriacou
- School of Mathematics, Computer Sciences and Engineering, City, University of London, London, UK
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Charlton PH, Bonnici T, Tarassenko L, Alastruey J, Clifton DA, Beale R, Watkinson PJ. Extraction of respiratory signals from the electrocardiogram and photoplethysmogram: technical and physiological determinants. Physiol Meas 2017; 38:669-690. [PMID: 28296645 DOI: 10.1088/1361-6579/aa670e] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Breathing rate (BR) can be estimated by extracting respiratory signals from the electrocardiogram (ECG) or photoplethysmogram (PPG). The extracted respiratory signals may be influenced by several technical and physiological factors. In this study, our aim was to determine how technical and physiological factors influence the quality of respiratory signals. APPROACH Using a variety of techniques 15 respiratory signals were extracted from the ECG, and 11 from PPG signals collected from 57 healthy subjects. The quality of each respiratory signal was assessed by calculating its correlation with a reference oral-nasal pressure respiratory signal using Pearson's correlation coefficient. MAIN RESULTS Relevant results informing device design and clinical application were obtained. The results informing device design were: (i) seven out of 11 respiratory signals were of higher quality when extracted from finger PPG compared to ear PPG; (ii) laboratory equipment did not provide higher quality of respiratory signals than a clinical monitor; (iii) the ECG provided higher quality respiratory signals than the PPG; (iv) during downsampling of the ECG and PPG significant reductions in quality were first observed at sampling frequencies of <250 Hz and <16 Hz respectively. The results informing clinical application were: (i) frequency modulation-based respiratory signals were generally of lower quality in elderly subjects compared to young subjects; (ii) the qualities of 23 out of 26 respiratory signals were reduced at elevated BRs; (iii) there were no differences associated with gender. SIGNIFICANCE Recommendations based on the results are provided regarding device designs for BR estimation, and clinical applications. The dataset and code used in this study are publicly available.
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Affiliation(s)
- Peter H Charlton
- School of Medicine, King's College London, United Kingdom. Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, United Kingdom
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30
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Harju J, Vehkaoja A, Lindroos V, Kumpulainen P, Liuhanen S, Yli-Hankala A, Oksala N. Determination of saturation, heart rate, and respiratory rate at forearm using a Nellcor™ forehead SpO 2-saturation sensor. J Clin Monit Comput 2016; 31:1019-1026. [PMID: 27752932 DOI: 10.1007/s10877-016-9940-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 10/07/2016] [Indexed: 11/29/2022]
Abstract
Alterations in arterial blood oxygen saturation, heart rate (HR), and respiratory rate (RR) are strongly associated with intra-hospital cardiac arrests and resuscitations. A wireless, easy-to-use, and comfortable method for monitoring these important clinical signs would be highly useful. We investigated whether the Nellcor™ OxiMask MAX-FAST forehead sensor could provide data for vital sign measurements when located at the distal forearm instead of its intended location at the forehead to provide improved comfortability and easy placement. In a prospective setting, we recruited 30 patients undergoing surgery requiring postoperative care. At the postoperative care unit, patients were monitored for two hours using a standard patient monitor and with a study device equipped with a Nellcor™ Forehead SpO2 sensor. The readings were electronically recorded and compared in post hoc analysis using Bland-Altman plots, Spearman's correlation, and root-mean-square error (RMSE). Bland-Altman plot showed that saturation (SpO2) differed by a mean of -0.2 % points (SD, 4.6), with a patient-weighted Spearman's correlation (r) of 0.142, and an RMSE of 4.2 points. For HR measurements, the mean difference was 0.6 bpm (SD, 2.5), r = 0.997, and RMSE = 1.8. For RR, the mean difference was -0.5 1/min (4.1), r = 0.586, and RMSE = 4.0. The SpO2 readings showed a low mean difference, but also a low correlation and high RMSE, indicating that the Nellcor™ saturation sensor cannot reliably assess oxygen saturation at the forearm when compared to finger PPG measurements.
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Affiliation(s)
- Jarkko Harju
- Department of Anesthesia, Tampere University Hospital, PL2000, 33521, Tampere, Finland.
| | | | | | | | - Sasu Liuhanen
- Department of Anesthesia, Helsinki University Hospital, Helsinki, Finland
| | - Arvi Yli-Hankala
- Department of Anesthesia, Tampere University Hospital, PL2000, 33521, Tampere, Finland.,Medical School, University of Tampere, Tampere, Finland
| | - Niku Oksala
- Medical School, University of Tampere, Tampere, Finland.,Department of Surgery, Tampere University Hospital, Tampere, Finland
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31
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Chreiteh SS, Belhage B, Hoppe K, Branebjerg J, Haahr R, Duun S, Thomsen EV. Estimation of respiratory rates based on photoplethysmographic measurements at the sternum. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2015:6570-3. [PMID: 26737798 DOI: 10.1109/embc.2015.7319898] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The respiratory rate (RR) is a clinically important vital sign and is a frequently used parameter in the general hospital wards. In current clinical practice, the monitoring of the RR is by manual count of the chest movement for one minute. This paper addresses a new approach where the respiratory rate is extracted using photoplethysmography (PPG) on the chest bone (sternum). Sternal PPG signals were acquired from 10 healthy subjects resting in a supine position. As reference signals, finger PPG, electrocardiogram (ECG), and capnography were simultaneously recorded during spontaneous and paced breathing. The sternal PPG signals were then compared with the reference signals in terms of Bland-Altman analysis, the power spectrum analysis and the magnitude squared coherence. The Bland-Altman analysis showed an average bias of 0.21 breaths/min between RR extracted from sternal PPG and capnography. The respiratory power content at the sternum was 78.8 (38) % in terms of the median and (the interquartile range). The cardiac content was 19 (18.4) % within the cardiac region. The results from the magnitude squared coherence analysis was 0.97 (0.09) in the respiratory region (6 to 27 breaths/min) and 0.98 (0.01) in the cardiac pulse region (30-120 beats/min). This preliminary study demonstrates the possibility of monitoring the RR from sternal PPG on a healthy group of subjects during rest.
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32
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Cross time-frequency analysis for combining information of several sources: application to estimation of spontaneous respiratory rate from photoplethysmography. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2013; 2013:631978. [PMID: 24363777 PMCID: PMC3864101 DOI: 10.1155/2013/631978] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Revised: 10/29/2013] [Accepted: 11/06/2013] [Indexed: 12/03/2022]
Abstract
A methodology that combines information from several nonstationary biological signals is presented. This methodology is based on time-frequency coherence, that quantifies the similarity of two signals in the time-frequency domain. A cross time-frequency analysis method, based on quadratic time-frequency distribution, has been used for combining information of several nonstationary biomedical signals. In order to evaluate this methodology, the respiratory rate from the photoplethysmographic (PPG) signal is estimated. The respiration provokes simultaneous changes in the pulse interval, amplitude, and width of the PPG signal. This suggests that the combination of information from these sources will improve the accuracy of the estimation of the respiratory rate. Another target of this paper is to implement an algorithm which provides a robust estimation. Therefore, respiratory rate was estimated only in those intervals where the features extracted from the PPG signals are linearly coupled. In 38 spontaneous breathing subjects, among which 7 were characterized by a respiratory rate lower than 0.15 Hz, this methodology provided accurate estimates, with the median error {0.00; 0.98} mHz ({0.00; 0.31}%) and the interquartile range error {4.88; 6.59} mHz ({1.60; 1.92}%). The estimation error of the presented methodology was largely lower than the estimation error obtained without combining different PPG features related to respiration.
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33
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Dash S, Shelley KH, Silverman DG, Chon KH. Estimation of Respiratory Rate From ECG, Photoplethysmogram, and Piezoelectric Pulse Transducer Signals: A Comparative Study of Time–Frequency Methods. IEEE Trans Biomed Eng 2010; 57:1099-107. [DOI: 10.1109/tbme.2009.2038226] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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34
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Wong MM, Leung HK, Pickwell-MacPherson E, Gu WB, Zhang YT. Contactless recording of photoplethysmogram on a sleeping bed. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2009:907-10. [PMID: 19964944 DOI: 10.1109/iembs.2009.5334560] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
This paper reports a novel contactless monitoring method to record reflective mode photoplethysmogram (PPG) on a sleeping bed for heart rate (HR) estimation. The electrocardiogram (ECG) and pulse transit time (PTT) were also measured in this study. ECG was measured from subjects' limbs whilst PPG was obtained from their right index fingers and their backs with and without direct contact between the PPG sensor and the subjects' skin respectively. Clear PPG waveforms were obtained from the subjects' backs even though the sensor was not directly attached to their skin. Beat-to-beat HRs derived from the back PPGs were closely correlated with those measured from the finger PPGs and ECGs. Thus we found that contactless PPG could be captured from the subjects' backs to determine HR accurately.
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Affiliation(s)
- M M Wong
- Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong
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35
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Choi SJ, Ahn HJ, Yang MK, Kim CS, Sim WS, Kim JA, Kang JG, Kim JK, Kang JY. Comparison of desaturation and resaturation response times between transmission and reflectance pulse oximeters. Acta Anaesthesiol Scand 2010; 54:212-7. [PMID: 19719816 DOI: 10.1111/j.1399-6576.2009.02101.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND In general, there is a response time between actual arterial hypoxemia and its detection by pulse oximeters. We compared the desaturation and resaturation response times between two types of pulse oximeters, transmission and reflectance pulse oximeters, to find out which oximeter has a more rapid response time. METHODS Thirty-three ASA 1 or 2 patients were enrolled in this study. A transmission pulse oximeter was placed on the index finger and a reflectance pulse oximeter was placed on the forehead and monitored simultaneously. After the induction of general anesthesia without pre-oxygenation, we waited until the oxygen saturation value of any of two pulse oximeters declined to 90%, and then mask ventilation was started with 100% oxygen. Oxygen saturation was recorded at an interval of 2 s during this time. RESULTS The desaturation response time of SpO(2) to 95% after apnea was 82.0 s (interquartile range: 67.0-98.5 s) vs. 94.0 s (interquartile range: 84.0-106.5 s) (P<0.001) and SpO(2) to 90% was 94.0 s (interquartile range: 75.5-109.5 s) vs. 100.0 s (interquartile range: 84.5-114.5 s) (P<0.001) in the reflectance and transmission oximeters, respectively. The resaturation response time from mask ventilation to 100% SpO(2) was 23.2+/-5.6 vs. 28.9+/-7.6 s (P<0.001) in the reflectance and transmission oximeters, respectively. CONCLUSION In clinical situations in which rapid changes in oxygen saturation are expected, we recommend the forehead reflectance pulse oximeter because it responds more quickly in detecting oxygen desaturation and resaturation compared with the transmission pulse oximeter.
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Affiliation(s)
- S J Choi
- Department of Anesthesiology and Pain Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Kangnam-Ku, Seoul, Korea
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36
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Ginosar Y, Weiniger CF, Meroz Y, Kurz V, Bdolah-Abram T, Babchenko A, Nitzan M, Davidson EM. Pulse oximeter perfusion index as an early indicator of sympathectomy after epidural anesthesia. Acta Anaesthesiol Scand 2009; 53:1018-26. [PMID: 19397502 DOI: 10.1111/j.1399-6576.2009.01968.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The pulse oximeter perfusion index (PI) has been used to indicate sympathectomy-induced vasodilatation. We hypothesized that pulse oximeter PI provides an earlier and clearer indication of sympathectomy following epidural anesthesia than skin temperature and arterial pressure. METHODS Forty patients received lumbar epidural catheters. Patients were randomized to receive either 10 ml 0.5% bupivacaine or 10 ml 0.25% bupivacaine. PI in the toe, mean arterial pressure (MAP) and toe temperature were all assessed at baseline and at 5, 10 and 20 min following epidural anesthesia. The effect of epidural anesthesia over time was assessed by repeated measures analysis of variance. Additionally, we defined clinically evident sympathectomy criteria (a 100% increase in the PI, a 15% decrease in MAP and a 1 degrees C increase in toe temperature). The numbers of patients demonstrating these changes for each test were compared using the McNemar test for each time point. RESULTS Twenty-nine subjects had photoplethysmography signals that met a priori signal quality criteria for analysis. By 20 min, PI increased by 326%, compared with a 10% decrease and a 3% increase in MAP and toe temperature, respectively. For PI 15/29, 26/29 and 29/29 of the subjects met the sympathectomy criteria at 5, 10 and 20 min, respectively, compared with 4/29, 6/29 and 18/29 for MAP changes and 3/29, 8/29 and 14/29 for toe temperature changes. CONCLUSIONS PI was an earlier, clearer and more sensitive indicator of the development of epidural-induced sympathectomy than either skin temperature or MAP.
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Affiliation(s)
- Y Ginosar
- Mother and Child Anesthesia Center, Department of Anesthesiology and Critical Care Medicine, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
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