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Ruiz-Margáin A, Macías-Rodríguez RU, Flores-García NC, Román Calleja BM, Fierro-Angulo OM, González-Regueiro JA. Assessing nutrition status, sarcopenia, and frailty in adult transplant recipients. Nutr Clin Pract 2024; 39:14-26. [PMID: 38097210 DOI: 10.1002/ncp.11107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/15/2023] [Accepted: 11/15/2023] [Indexed: 01/13/2024] Open
Abstract
The assessment of nutrition status, sarcopenia, and frailty holds significant relevance in the context of adult transplantation, as these factors are associated with an unfavorable prognosis; thus, transplant candidates must undergo a full nutrition assessment. Screening tools may be used to prioritize patients, this can be done using the Nutrition Risk Screening 2002 or Royal Free Hospital-Nutritional Prioritizing Tool. Subsequently, a thorough nutrition-focused physical examination should be conducted to evaluate clinical signs of nutrition deficiencies, fat and muscle loss, and fluid overload; dietary history and current intake must also be assessed. Apart from physical examination, specific testing for sarcopenia and frailty are recommended. For sarcopenia assessment, specifically for muscle quantification, the gold standard is the cross-sectional measurement of the muscle at L3 obtained from a computed tomography scan or magnetic resonance imaging; dual-energy x-ray absorptiometry is also a good tool especially when appendicular skeletal muscle index is calculated. Other more readily available options include phase angle from bioelectrical impedance or bioimpedance spectroscopy. In the sarcopenia assessment, muscle function evaluation is required, handgrip strength stands as the primary test for this purpose; this test is also part of the subjective global assessment and is included in some frailty scores. Finally, for frailty assessment, the Short Physical Performance Battery is useful for evaluating physical frailty, and for a multidimensional evaluation, the Fried frailty phenotype can be used. Specifically for liver transplant candidates, the use of Liver Frailty Index is recommended.
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Affiliation(s)
- Astrid Ruiz-Margáin
- Division of Hepatology, Department of Gastroenterology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Ricardo U Macías-Rodríguez
- Division of Hepatology, Department of Gastroenterology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Nayelli C Flores-García
- Division of Hepatology, Department of Gastroenterology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Berenice M Román Calleja
- Division of Hepatology, Department of Gastroenterology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Oscar M Fierro-Angulo
- Division of Hepatology, Department of Gastroenterology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - José A González-Regueiro
- Division of Hepatology, Department of Gastroenterology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
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2
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Kong MG, Moon I, Seo HS, Suh J, Choi JY, Na JO, Kim EJ. Home Bioelectrical Impedance Analysis Management System in Patients With Heart Failure: Rationale and Study Design. INTERNATIONAL JOURNAL OF HEART FAILURE 2024; 6:22-27. [PMID: 38303915 PMCID: PMC10827698 DOI: 10.36628/ijhf.2023.0018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 07/25/2023] [Accepted: 08/11/2023] [Indexed: 02/03/2024]
Abstract
Body fluid monitoring and management are essential to control dyspnea and prevent re-hospitalization in patients with chronic heart failure (HF). There are several methods to estimate and monitor patient's volume status, such as symptoms, signs, body weight, and implantable devices. However, these methods might be difficult to use for reasons that are slow to reflect body water change, inaccurate in specific patients' condition, or invasive. Bioelectrical impedance analysis (BIA) is a novel method for body water monitoring in patients with HF, and the value in prognosis has been proven in previous studies. We aim to determine the efficacy and safety of home BIA body water monitoring-guided HF treatment in patients with chronic HF. This multi-center, open-label, randomized control trial will enroll patients with HF who are taking loop diuretics. The home BIA group patients will be monitored for body water using a home BIA device and receive messages regarding their edema status and direction of additional diuretics usage or behavioral changes through the linked application system once weekly. The control group patients will receive the usual HF management. The primary endpoint is the change in N-terminal prohormone of brain natriuretic peptide levels from baseline after 12 weeks. This trial will provide crucial evidence for patient management with a novel home BIA body water monitoring system in patients with HF.
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Affiliation(s)
- Min Gyu Kong
- Division of Cardiology, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea
| | - Inki Moon
- Division of Cardiology, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea
| | - Hye-Sun Seo
- Division of Cardiology, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea
| | - Jon Suh
- Division of Cardiology, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Soonchunhyang University College of Medicine, Bucheon, Korea
| | - Jah Yeon Choi
- Division of Cardiology, Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea
| | - Jin Oh Na
- Division of Cardiology, Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea
| | - Eung Ju Kim
- Division of Cardiology, Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea
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Aggas JR, Abasi S, Ton C, Salehi S, Liu R, Brandacher G, Grayson WL, Guiseppi-Elie A. Real-Time Monitoring Using Multiplexed Multi-Electrode Bioelectrical Impedance Spectroscopy for the Stratification of Vascularized Composite Allografts: A Perspective on Predictive Analytics. Bioengineering (Basel) 2023; 10:bioengineering10040434. [PMID: 37106621 PMCID: PMC10135882 DOI: 10.3390/bioengineering10040434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 03/20/2023] [Accepted: 03/24/2023] [Indexed: 04/29/2023] Open
Abstract
Vascularized composite allotransplantation addresses injuries to complex anatomical structures such as the face, hand, and abdominal wall. Prolonged static cold storage of vascularized composite allografts (VCA) incurs damage and imposes transportation limits to their viability and availability. Tissue ischemia, the major clinical indication, is strongly correlated with negative transplantation outcomes. Machine perfusion and normothermia can extend preservation times. This perspective introduces multiplexed multi-electrode bioimpedance spectroscopy (MMBIS), an established bioanalytical method to quantify the interaction of the electrical current with tissue components, capable of measuring tissue edema, as a quantitative, noninvasive, real-time, continuous monitoring technique to provide crucially needed assessment of graft preservation efficacy and viability. MMBIS must be developed, and appropriate models explored to address the highly complex multi-tissue structures and time-temperature changes of VCA. Combined with artificial intelligence (AI), MMBIS can serve to stratify allografts for improvement in transplantation outcomes.
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Affiliation(s)
- John R Aggas
- Bioelectronics, Biosensors and Biochips (C3B®), Department of Biomedical Engineering, Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX 77843, USA
- Test Development, Roche Diagnostics, 9115 Hague Road, Indianapolis, IN 46256, USA
| | - Sara Abasi
- Bioelectronics, Biosensors and Biochips (C3B®), Department of Biomedical Engineering, Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX 77843, USA
- Media and Metabolism, Wildtype, Inc., 2325 3rd St., San Francisco, CA 94107, USA
| | - Carolyn Ton
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21231, USA
- Translational Tissue Engineering Center, Johns Hopkins University, Baltimore, MD 21231, USA
| | - Sara Salehi
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21231, USA
- Translational Tissue Engineering Center, Johns Hopkins University, Baltimore, MD 21231, USA
| | - Renee Liu
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21231, USA
- Translational Tissue Engineering Center, Johns Hopkins University, Baltimore, MD 21231, USA
| | - Gerald Brandacher
- Translational Tissue Engineering Center, Johns Hopkins University, Baltimore, MD 21231, USA
- Department of Plastic & Reconstructive Surgery, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Warren L Grayson
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21231, USA
- Translational Tissue Engineering Center, Johns Hopkins University, Baltimore, MD 21231, USA
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
- Institute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Anthony Guiseppi-Elie
- Bioelectronics, Biosensors and Biochips (C3B®), Department of Biomedical Engineering, Department of Electrical and Computer Engineering, Texas A&M University, College Station, TX 77843, USA
- Department of Cardiovascular Sciences, Houston Methodist Institute for Academic Medicine and Houston Methodist Research Institute, 6670 Bertner Ave., Houston, TX 77030, USA
- ABTECH Scientific, Inc., Biotechnology Research Park, 800 East Leigh Street, Richmond, VA 23219, USA
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Buchner T, Zajdel M, Pȩczalski K, Nowak P. Finite velocity of ECG signal propagation: preliminary theory, results of a pilot experiment and consequences for medical diagnosis. Sci Rep 2023; 13:4716. [PMID: 36949077 PMCID: PMC10033722 DOI: 10.1038/s41598-023-29904-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 02/13/2023] [Indexed: 03/24/2023] Open
Abstract
A satisfactory model of the biopotentials propagating through the human body is essential for medical diagnostics, particularly for cardiovascular diseases. In our study, we develop the theory, that the propagation of biopotential of cardiac origin (ECG signal) may be treated as the propagation of low-frequency endogenous electromagnetic wave through the human body. We show that within this approach, the velocity of the ECG signal can be theoretically estimated, like for any other wave and physical medium, from the refraction index of the tissue in an appropriate frequency range. We confirm the theoretical predictions by the comparison with a direct measurement of the ECG signal propagation velocity and obtain mean velocity as low as v=1500 m/s. The results shed new light on our understanding of biopotential propagation through living tissue. This propagation depends on the frequency band of the signal and the transmittance of the tissue. This finding may improve the interpretation of the electric measurements, such as ECG and EEG when the frequency dependence of conductance and the phase shift introduced by the tissue is considered. We have shown, that the ECG propagation modifies the amplitude and phase of signal to a considerable extent. It may also improve the convergence of inverse problem in electrocardiographic imaging.
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Affiliation(s)
- Teodor Buchner
- Faculty of Physics, Warsaw University of Technology, Warsaw, Poland.
| | - Maryla Zajdel
- Faculty of Physics, Warsaw University of Technology, Warsaw, Poland
| | | | - Paweł Nowak
- Faculty of Mechatronics, Warsaw University of Technology, Warsaw, Poland
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5
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Sanchez-Perez JA, Berkebile JA, Nevius BN, Ozmen GC, Nichols CJ, Ganti VG, Mabrouk SA, Clifford GD, Kamaleswaran R, Wright DW, Inan OT. A Wearable Multimodal Sensing System for Tracking Changes in Pulmonary Fluid Status, Lung Sounds, and Respiratory Markers. SENSORS 2022; 22:s22031130. [PMID: 35161876 PMCID: PMC8838360 DOI: 10.3390/s22031130] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/23/2022] [Accepted: 01/29/2022] [Indexed: 12/17/2022]
Abstract
Heart failure (HF) exacerbations, characterized by pulmonary congestion and breathlessness, require frequent hospitalizations, often resulting in poor outcomes. Current methods for tracking lung fluid and respiratory distress are unable to produce continuous, holistic measures of cardiopulmonary health. We present a multimodal sensing system that captures bioimpedance spectroscopy (BIS), multi-channel lung sounds from four contact microphones, multi-frequency impedance pneumography (IP), temperature, and kinematics to track changes in cardiopulmonary status. We first validated the system on healthy subjects (n = 10) and then conducted a feasibility study on patients (n = 14) with HF in clinical settings. Three measurements were taken throughout the course of hospitalization, and parameters relevant to lung fluid status—the ratio of the resistances at 5 kHz to those at 150 kHz (K)—and respiratory timings (e.g., respiratory rate) were extracted. We found a statistically significant increase in K (p < 0.05) from admission to discharge and observed respiratory timings in physiologically plausible ranges. The IP-derived respiratory signals and lung sounds were sensitive enough to detect abnormal respiratory patterns (Cheyne–Stokes) and inspiratory crackles from patient recordings, respectively. We demonstrated that the proposed system is suitable for detecting changes in pulmonary fluid status and capturing high-quality respiratory signals and lung sounds in a clinical setting.
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Affiliation(s)
- Jesus Antonio Sanchez-Perez
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30313, USA; (J.A.B.); (G.C.O.); (S.A.M.); (O.T.I.)
- Correspondence:
| | - John A. Berkebile
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30313, USA; (J.A.B.); (G.C.O.); (S.A.M.); (O.T.I.)
| | - Brandi N. Nevius
- Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA;
| | - Goktug C. Ozmen
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30313, USA; (J.A.B.); (G.C.O.); (S.A.M.); (O.T.I.)
| | - Christopher J. Nichols
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, GA 30332, USA; (C.J.N.); (G.D.C.); (R.K.)
| | - Venu G. Ganti
- Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, GA 30332, USA;
| | - Samer A. Mabrouk
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30313, USA; (J.A.B.); (G.C.O.); (S.A.M.); (O.T.I.)
| | - Gari D. Clifford
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, GA 30332, USA; (C.J.N.); (G.D.C.); (R.K.)
- Department of Biomedical Informatics, Emory University, Atlanta, GA 30332, USA
| | - Rishikesan Kamaleswaran
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, GA 30332, USA; (C.J.N.); (G.D.C.); (R.K.)
- Department of Biomedical Informatics, Emory University, Atlanta, GA 30332, USA
- Department of Emergency Medicine, Emory University, Atlanta, GA 30332, USA;
| | - David W. Wright
- Department of Emergency Medicine, Emory University, Atlanta, GA 30332, USA;
| | - Omer T. Inan
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30313, USA; (J.A.B.); (G.C.O.); (S.A.M.); (O.T.I.)
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, GA 30332, USA; (C.J.N.); (G.D.C.); (R.K.)
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Short-Time Impedance Spectroscopy Using a Mode-Switching Nonsinusoidal Oscillator: Applicability to Biological Tissues and Continuous Measurement. SENSORS 2021; 21:s21216951. [PMID: 34770258 PMCID: PMC8587290 DOI: 10.3390/s21216951] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Revised: 10/13/2021] [Accepted: 10/18/2021] [Indexed: 01/04/2023]
Abstract
Herein, we propose an impedance spectroscopy method using a mode-switching nonsinusoidal oscillator and apply this method for measuring the impedance of biological tissues and continuous impedance measurement. To obtain impedance spectra over a wide frequency range, we fabricated a novel nonsinusoidal oscillator incorporating binary counters and analog switches. This oscillator could periodically switch oscillation frequency through the mode switching of the feedback resistor. From the oscillation waveform at each oscillation frequency of this circuit (oscillator), we determined the impedance spectrum of a measured object using the discrete-time Fourier transform. Subsequently, we obtained the broad impedance spectrum of the measured object by merging odd-order harmonic spectral components up to the 19th order for each oscillation frequency. From the measured spectrum, the resistive and capacitive components of the circuit simulating bioimpedance were estimated with high accuracy. Moreover, the proposed method was used to measure the impedance of porcine myocardium; changes in the impedance spectrum of the myocardial tissue due to coagulation could be measured. Furthermore, rapid variations in the resistance value of a CdS photocell could be continuously measured using the proposed method.
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7
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Eduardo PM, Mario GL, Carlos César PM, Mayra MA, Sara HY, E BN. Bioelectric, tissue, and molecular characteristics of the gastric mucosa at different times of ischemia. Exp Biol Med (Maywood) 2021; 246:1968-1980. [PMID: 34130514 PMCID: PMC8474982 DOI: 10.1177/15353702211021601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 05/13/2021] [Indexed: 11/16/2022] Open
Abstract
Gastrointestinal ischemia may be presented as a complication associated with late shock detection in patients in critical condition. Prolonged ischemia can cause mucosal integrity to lose its barrier function, triggering alterations that can induce organ dysfunction and lead to death. Electrical impedance spectroscopy has been proposed to identify early alteration in ischemia-induced gastric mucosa in this type of patients. This work analyzed changes in impedance parameters, and tissue and molecular alterations that allow us to identify the time of ischemia in which the gastric mucosa still maintains its barrier function. The animals were randomly distributed in four groups: Control, Ischemia 60, 90, and 120 min. Impedance parameters were measured and predictive values were determined to categorize the degree of injury using a receiver operating characteristic curve. Markers of inflammatory process and apoptosis (iNOS, TNFα, COX-2, and Caspase-3) were analyzed. The largest increase in impedance parameters occurred in the ischemia 90 and 120 min groups, with resistance at low frequencies (RL) and reactance at high frequencies (XH) being the most related to damage, allowing prediction of the occurrence of reversible and irreversible tissue damage. Histological analysis and apoptosis assay showed progressive mucosal deterioration with irreversible damage (p < 0.001) starting from 90 min of ischemia. Furthermore, a significant increase in the expression of iNOS, TNFα, and COX-2 was identified in addition to apoptosis in the gastric mucosa starting from 90 min of ischemia. Tissue damage generated by an ischemia time greater than 60 min induces loss of barrier function in the gastric mucosa.
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Affiliation(s)
- Peña-Mercado Eduardo
- Posgrado en Ciencias Naturales e Ingenieria, Unidad Cuajimalpa,
Universidad Autonoma Metropolitana, CDMX 05340, Mexico
| | - Garcia-Lorenzana Mario
- Departamento de Biologia de la Reproduccion, Unidad Iztapalapa,
Universidad Autonoma Metropolitana, CDMX 09340, Mexico
| | - Patiño-Morales Carlos César
- Laboratorio de Investigacion en Biologia del Desarrollo y
Teratogenesis Experimental, Hospital Infantil de Mexico, Federico Gomez, CDMX
06720, Mexico
| | - Montecillo-Aguado Mayra
- Doctorado en Ciencias Biologicas, Facultad de Medicina,
Universidad Nacional Autonoma de Mexico, CDMX 04510, Mexico
| | - Huerta-Yepez Sara
- Unidad de Investigacion en Enfermedades Hematoncologicas,
Hospital Infantil de Mexico, Federico Gomez, CDMX 06720, Mexico
| | - Beltran Nohra E
- Departamento de Procesos y Tecnologia, Unidad Cuajimalpa,
Universidad Autonoma Metropolitana, CDMX 05340, Mexico
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Accardi AJ, Matsubara BS, Gaw RL, Daleiden-Burns A, Heywood JT. Clinical Utility of Fluid Volume Assessment in Heart Failure Patients Using Bioimpedance Spectroscopy. Front Cardiovasc Med 2021; 8:636718. [PMID: 33898536 PMCID: PMC8060148 DOI: 10.3389/fcvm.2021.636718] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 03/12/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Bioimpedance spectroscopy (BIS) is a non-invasive method used to measure fluid volumes. In this report, we compare BIS measurements from patients with heart failure (HF) to those from healthy adults, and describe how these point-of-care fluid volume assessments may be applied to HF management. Methods and results: Fluid volumes were measured in 64 patients with NYHA class II or III HF and 69 healthy control subjects. BIS parameters including extracellular fluid (ECF), intracellular fluid (ICF), total body water (TBW), and ECF as a percentage of TBW (ECF%TBW) were analyzed. ECF%TBW values for the HF and control populations differed significantly (49.2 ± 3.2% vs. 45.2 ± 2.1%, respectively; p < 0.001); both distributions satisfied criteria for normality. Interquartile ranges did not overlap (46.7–51.0% vs. 43.8–46.4%, respectively; p < 0.001). Subgroup analyses of HF patients who underwent transthoracic echocardiography showed that impedance measurements correlated with inferior vena cava size (Pearson correlation −0.73, p < 0.0001). A case study is presented for illustrative purposes. Conclusions: BIS-measured ECF%TBW values were significantly higher in HF patients as compared to adults without HF. We describe three strata of ECF%TBW (normal, elevated, fluid overload) that may aid in clinical risk stratification and fluid volume monitoring of HF patients. Clinical Trial Registration: COMPARE – www.ClinicalTrials.gov; IMPEL – www.ClinicalTrials.gov; Heart Failure at Home – www.ClinicalTrials.gov, identifier: NCT02939053; NCT02857231; NCT04013373.
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Affiliation(s)
- Andrew J Accardi
- Department of Emergency Medicine, Scripps Memorial Hospital Encinitas, Encinitas, CA, United States
| | | | | | - Anne Daleiden-Burns
- Heart Failure Recovery and Research Program, Scripps Memorial Hospital La Jolla, La Jolla, CA, United States
| | - James Thomas Heywood
- Heart Failure Recovery and Research Program, Scripps Memorial Hospital La Jolla, La Jolla, CA, United States
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Dheman K, Mayer P, Magno M, Schuerle S. Wireless, Artefact Aware Impedance Sensor Node for Continuous Bio-Impedance Monitoring. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2020; 14:1122-1134. [PMID: 32877339 DOI: 10.1109/tbcas.2020.3021186] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Body bio-impedance is a unique parameter to monitor changes in body composition non-invasively. Continuous measurement of bio-impedance can track changes in body fluid content and cell mass and has widespread applications for physiological monitoring. State-of-the-art implementation of bio-impedance sensor devices is still limited for continuous use, in part, due to artefacts arising at the skin-electrode (SE) interface. Artefacts at the SE interface may arise due to various factors such as motion, applied pressure on the electrode surface, changes in ambient conditions or gradual drying of electrodes. This paper presents a novel bio-impedance sensor node that includes an artefact aware method for bio-impedance measurement. The sensor node enables autonomous and continuous measurement of bio-impedance and SE contact impedance at ten frequencies between 10 kHz to 100 kHz to detect artefacts at the SE interface. Experimental evaluation with SE contact impedance models using passive 2R1C electronic circuits and also with non-invasive in vivo measurements of SE contact impedance demonstrated high accuracy (with maximum error less than 1.5%) and precision of 0.6 Ω. The ability to detect artefacts caused by motion, vertically applied pressure and skin temperature changes was analysed in proof of concept experiments. Low power sensor node design achieved with 50mW in active mode and only 143 μW in sleep mode estimated a battery life of 90 days with a 250 mAh battery and duty-cycling impedance measurements every 60 seconds. Our method for artefact aware bio-impedance sensing is a step towards autonomous and unobtrusive continuous bio-impedance measurement for health monitoring at-home or in clinical environments.
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