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Nguyen TH, Nguyen KT, Tran LD, Le ATT, Phung TM, Banh TTN, Vo TT, Bodo M. Characteristics of Rheoencephalography and some Associated Factors on Menopausal Women. JOURNAL OF ELECTRICAL BIOIMPEDANCE 2022; 13:78-87. [PMID: 36699666 PMCID: PMC9837873 DOI: 10.2478/joeb-2022-0012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Indexed: 06/17/2023]
Abstract
The significant drop in estrogen levels during menopause increases the cardiovascular risks, one of which is cerebrovascular atherosclerosis. Research on rheoencephalography (REG) parameters for the early diagnosis of cerebrovascular atherosclerotic lesions is of great interest to scientists because of its ease of implementation, low cost, and non-invasiveness. The objectives of study are to evaluate the vascular tone, cerebral circulation flow in each hemisphere of the brain of menopausal women, and some associated factors through waveform characteristics and parameters in REG. A controlled cross-sectional descriptive study was conducted on a group of patients including 80 menopausal women and a control group of 46 menstruating women. All patients were measured REG in the frontal-occipital leads by VasoScreen 5000 impedance REG meter. In menopausal women, the percentage of sharp waves, the percentage of clear side waves, and the average REG were all lower than in the control group (p<0.01). The mean conduction time and mean slope ratio was lower than the control group (p<0.001). The mean peak time was higher than the control group (p<0.01). The mean elasticity index (alpha/T) was higher than the control group (p<0.001). Menopausal women have increased vascular tone, the highest in the group of women 50-60 years old, menopause <5 years, having a habit of eating red meat; and decreased blood flow intensity, the highest in the group of women <50 years old. However, the difference was statistically significant only in the left hemisphere (p<0.05). Vascular hypertonia in menopausal women with central obesity was higher than in the non-obese group in both hemispheres (p<0.05). In conclusion, menopausal women had atherosclerosis in both hemispheres of the brain, which was clearly shown in the rate of increased vascular tone. Central obesity may increase the risk of vascular hypertonia 3.75 times in the right and 5.44 times in the left hemisphere.
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Affiliation(s)
- Tin Hoang Nguyen
- Faculty of Medicine, Can Tho University of Medicine and Pharmacy, Can Tho, Vietnam
- Department of Functional Diagnostics, Can Tho University of Medicine and Pharmacy Hospital, Can Tho, Vietnam
| | - Kien Trung Nguyen
- Faculty of Medicine, Can Tho University of Medicine and Pharmacy, Can Tho, Vietnam
| | - Long Duc Tran
- Faculty of Medicine, Can Tho University of Medicine and Pharmacy, Can Tho, Vietnam
| | - An Thi Thuy Le
- Faculty of Medicine, Can Tho University of Medicine and Pharmacy, Can Tho, Vietnam
| | - Thu Minh Phung
- Faculty of Medicine, Can Tho University of Medicine and Pharmacy, Can Tho, Vietnam
| | - Truc Thi Ngoc Banh
- Faculty of Medicine, Can Tho University of Medicine and Pharmacy, Can Tho, Vietnam
| | - Trang Thi Vo
- Department of Functional Diagnostics, Can Tho University of Medicine and Pharmacy Hospital, Can Tho, Vietnam
| | - Michael Bodo
- Department of Neurocritical Care, Ochsner Medical Center, New Orleans, LA, USA
- Uniformed Services University of the Health Sciences, Bethesda, MD, USA
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Bronk TS, Everitt AC, Murphy EK, Halter RJ. Novel Electrode Placement in Electrical Bioimpedance-Based Stroke Detection: Effects on Current Penetration and Injury Characterization in a Finite Element Model. IEEE Trans Biomed Eng 2021; 69:1745-1757. [PMID: 34813463 PMCID: PMC9172913 DOI: 10.1109/tbme.2021.3129734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Reducing time-to-treatment and providing acute management in stroke are essential for patient recovery. Electrical bioimpedance (EBI) is an inexpensive and non-invasive tissue measurement approach that has the potential to provide novel continuous intracranial monitoring-something not possible in current standard-of-care. While extensive previous work has evaluated the feasibility of EBI in diagnosing stroke, high-impedance anatomical features in the head have limited clinical translation. METHODS The present study introduces novel electrode placements near highly-conductive cerebral spinal fluid (CSF) pathways to enhance electrical current penetration through the skull and increase detection accuracy of neurologic damage. Simulations were conducted on a realistic finite element model (FEM). Novel electrode placements at the tear ducts, soft palate and base of neck were evaluated. Classification accuracy was assessed in the presence of signal noise, patient variability, and electrode positioning. RESULTS Algorithms were developed to successfully determine stroke etiology, location, and size relative to impedance measurements from a baseline scan. Novel electrode placements significantly increased stroke classification accuracy at various levels of signal noise (e.g. p < 0.001 at 40 dB). Novel electrodes also amplified current penetration, with up to 30% increase in current density and 57% increased sensitivity in central intracranial regions (p<0.001). CONCLUSION These findings support the use of novel electrode placements in EBI to overcome prior limitations, indicating a potential approach to increasing the technology's clinical utility in stroke identification. SIGNIFICANCE A non-invasive EBI monitor for stroke could provide essential timely intervention and care of stroke patients.
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Everitt A, Root B, Calnan D, Manwaring P, Bauer D, Halter R. A bioimpedance-based monitor for real-time detection and identification of secondary brain injury. Sci Rep 2021; 11:15454. [PMID: 34326387 PMCID: PMC8322167 DOI: 10.1038/s41598-021-94600-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 07/13/2021] [Indexed: 01/01/2023] Open
Abstract
Secondary brain injury impacts patient prognosis and can lead to long-term morbidity and mortality in cases of trauma. Continuous monitoring of secondary injury in acute clinical settings is primarily limited to intracranial pressure (ICP); however, ICP is unable to identify essential underlying etiologies of injury needed to guide treatment (e.g. immediate surgical intervention vs medical management). Here we show that a novel intracranial bioimpedance monitor (BIM) can detect onset of secondary injury, differentiate focal (e.g. hemorrhage) from global (e.g. edema) events, identify underlying etiology and provide localization of an intracranial mass effect. We found in an in vivo porcine model that the BIM detected changes in intracranial volume down to 0.38 mL, differentiated high impedance (e.g. ischemic) from low impedance (e.g. hemorrhagic) injuries (p < 0.001), separated focal from global events (p < 0.001) and provided coarse 'imaging' through localization of the mass effect. This work presents for the first time the full design, development, characterization and successful implementation of an intracranial bioimpedance monitor. This BIM technology could be further translated to clinical pathologies including but not limited to traumatic brain injury, intracerebral hemorrhage, stroke, hydrocephalus and post-surgical monitoring.
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Affiliation(s)
- Alicia Everitt
- Thayer School of Engineering, Dartmouth College, HB 8000, 14 Engineering Dr., Hanover, NH, 03755, USA.
| | - Brandon Root
- Neurological Surgery, Dartmouth Hitchcock Medical Center, Lebanon, NH, 03766, USA
| | - Daniel Calnan
- Neurological Surgery, Dartmouth Hitchcock Medical Center, Lebanon, NH, 03766, USA
| | | | - David Bauer
- Neurological Surgery, Dartmouth Hitchcock Medical Center, Lebanon, NH, 03766, USA
| | - Ryan Halter
- Thayer School of Engineering, Dartmouth College, HB 8000, 14 Engineering Dr., Hanover, NH, 03755, USA.,Neurological Surgery, Dartmouth Hitchcock Medical Center, Lebanon, NH, 03766, USA
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Meghdadi AH, Popovic D, Rupp G, Smith S, Berka C, Verma A. Transcranial Impedance Changes during Sleep: A Rheoencephalography Study. IEEE JOURNAL OF TRANSLATIONAL ENGINEERING IN HEALTH AND MEDICINE 2019; 7:2700107. [PMID: 30867999 PMCID: PMC6404797 DOI: 10.1109/jtehm.2019.2898193] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 12/24/2018] [Accepted: 01/23/2019] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To demonstrate the utility of rheoencephalography (REG) for measuring cerebral blood flow and fluid dynamics during different stages of sleep. METHODS Anteroposterior cranial electrical impedance was measured with concurrent polysomnography in a group of healthy subjects during sleep. Transcranial electrical impedance was characterized by measuring the peak-to-trough and envelope of the filtered pulsative REG signal as well as its frequency. The sensitivity of the REG amplitude to changes in cerebral blood flow (CBF) was confirmed by the analysis of the signal during breathing maneuvers with known effects on CBF. The mean amplitude and variability of the REG characteristic parameters were averaged across all participants and were compared between different stages of sleep. RESULTS Average transcranial impedance was significantly lower during non-REM stages N1 and N2, compared to other sleep stages, suggesting a decrease in CBF volume. Stage N3 showed the slowest frequency indicating a slow heart rate during this stage. N3 also had the lowest variability in frequency and peak-to-trough amplitude. CONCLUSION Measurement of transcranial electrical conductivity may be a viable non-invasive method for monitoring any potential changes in intracranial fluid homeostasis. Clinical Impact: In the absence of other convenient non-invasive methods, using REG to track intracranial fluid dynamics during sleep can facilitate an improved understanding of pathogenesis in Alzheimer's disease.
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Affiliation(s)
| | | | - Gregory Rupp
- Advanced Brain Monitoring, Inc.CarlsbadCA92008USA
| | | | - Chris Berka
- Advanced Brain Monitoring, Inc.CarlsbadCA92008USA
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Perez JJ. To what extent is the bipolar rheoencephalographic signal contaminated by scalp blood flow? A clinical study to quantify its extra and non-extracranial components. Biomed Eng Online 2014; 13:131. [PMID: 25192886 PMCID: PMC4169836 DOI: 10.1186/1475-925x-13-131] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 08/30/2014] [Indexed: 11/16/2022] Open
Abstract
Background Impedance plethysmography applied to the head by using a pair of electrodes attached to the scalp surface is known as bipolar Rheoencephalography or REG I and was originally proposed to measure changes in cerebral blood volume related to the heartbeat. REG I was soon discarded in favor of other REG configurations, since most of the signal was shown to be heavily contaminated by the extracranial blood flow. The main goal of this study was to identify and compare the part of the REG I signal caused by scalp blood flow with that originating from non-extracranial sources. Methods A clinical study involving thirty-six healthy volunteers was designed for this purpose. REG I was first registered in each subject under normal conditions. A pneumatic cuff was then placed around the head and was inflated to arrest the scalp blood flow and a second REG I was recorded. Finally, a third REG I was taken immediately after cuff deflation. Results The REG I signal is attenuated, but not extinguished, during cuff inflation in a wide subject-dependent range ratio from 0.12 to 0.68 (0.37 ± 0.15). The residual REG I signal has a waveform that is markedly different from that obtained before cuff inflation, which supports the hypothesis of the intracranial origin of the residual REG I signal. Additionally, an increase of 22% in REG I amplitude was observed when the head cuff was deflated. Conclusions Waveform differences between extra and non-extracranial components are significant and these differences could be used in a method to distinguish one from the other. However, a significant part of the REG I signal is caused by a non-extracranial source and, therefore, it should not be used as a footprint of the extracranial blood flow.
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Affiliation(s)
- Juan J Perez
- Bioelectronic Research Group (I3BH) (Ed, 7F), Universitat Politècnica de València, Cno de Vera s/n, Valencia, Spain.
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Siegman A, Abboud S. Bioimpedance technique for monitoring cerebral artery stenosis in a 3D numerical model of the head. Med Eng Phys 2011; 34:1095-100. [PMID: 22177574 DOI: 10.1016/j.medengphy.2011.11.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Revised: 10/02/2011] [Accepted: 11/24/2011] [Indexed: 11/29/2022]
Abstract
Insufficient blood supply to the brain causes a transient ischemic attack (TIA) or a stroke. One of the causes to insufficient blood supply is cerebral artery stenosis. In this study, the feasibility of bioimpedance for monitoring such stenosis was analyzed. Simulations were conducted on a realistic numerical model of the head, focusing on the left middle cerebral artery (LMCA). Tissues were assumed to act as linear isotropic volume conductors, and the quasi-static approximation was applied. Electrical potentials were calculated by solving Poisson's equation, using the finite volume method (FVM) and the successive over relaxation (SOR) method. The best sensitivity found was 0.471 μV/% stenosis, using this electrode configuration: one injector near the left eye and the other injector near the right ear, one measurement position near the left eye and the other one in the right ear, keeping a distance of at least 2.5 cm between measurement and injection positions. The maximal sensitivity achieved in the numerical model under the applied assumptions supports the feasibility of bioimpedance technique for monitoring cerebral artery stenosis. However, according to sensitivity [1/m(4)] maps, calculated for the preferable electrode configurations, the measurements' specificity to the stenosis degree might be inadequate and should be further studied.
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Affiliation(s)
- Ayelet Siegman
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv 69978, Israel
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Perez JJ, Guijarro E, Sancho J, Navarre A. Extraction of the intracranial component from the rheoencephalographic signal: a new approach. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2007; 2006:6064-7. [PMID: 17945931 DOI: 10.1109/iembs.2006.260544] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The well-known inherent artifact on the rheoencephalogram (REG) caused by the pulsatility of the scalp blood flow left the REG out of the clinical practice. In fact, depending on the selected electrode arrangement, the measurement of the brain impedance changes time-locked with the heartbeat can be completely buried on that of the scalp. In this work, a novel mathematical method based on the physiological differences between the brain and scalp perfusions is proposed to extract the intracranial information from REG. This method is experimentally applied to REG signals recorded at five electrode positions and results are compared with those derived from our previous theoretical works. Intracranial components extracted from the REG signals are consistent with the stated hypothesis and reproduce the unexpected results obtained with our theoretical models. Although further studies would be needed, the evidences found in this work suggest that the method proposed in this work extracts the intracranial information from the REG signal.
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Affiliation(s)
- Juan J Perez
- Center for Res. & Innovation on Bioeng., Univ. Politecnica de Valencia, Valencial, Spain.
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Guijarro E, Perez JJ, Berjano E, Ortiz P. Sensitivity of rheoencephalographic measurements to spatial brain electrical conductivity. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2007; 2006:6088-91. [PMID: 17946355 DOI: 10.1109/iembs.2006.260788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Rheoencephalography (REG) is impedance plethysmography applied to the head, and provides an indirect measurement of the pulsatility of the cerebral blood volume. To extend REG as a clinical and research tool, it is necessary to evaluate the sensitivity of REG measurement to local brain conductivity changes. By means of the analytical solution of a four-sphere geometrical model of the head, maps of impedance sensitivity were assessed for different electrode arrangements. Results showed a selective distribution of sensitivities, with a preference for cortical areas under electrodes. This suggests a potential for application of REG to regional evaluation of cortical cerebral perfusion.
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Affiliation(s)
- Enrique Guijarro
- Center for Res. & Innovation on Bioeng., Polytech. Valencia Univ., Valencial, Spain.
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Pérez JJ, Guijarro E, Sancho J. Spatiotemporal pattern of the extracranial component of the rheoencephalographic signal. Physiol Meas 2005; 26:925-38. [PMID: 16311442 DOI: 10.1088/0967-3334/26/6/004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The use of rheoencephalography (REG) in the clinical practice to evaluate cerebral blood flow is conditional on the finding of a method for removing the extracranial interference caused by the scalp blood flow. To remove this undesirable influence, digital processing based on statistics could be an effective technique if the appropriate data model were applied. This paper focuses on the analysis of the spatiotemporal features of the extracranial REG component, by comparing its morphology and phase shift at several scalp sites. For this purpose, a numerical model of the scalp was employed to assess tissue impedance changes caused by the inflow of a stepwise blood pulse wave. These results were compared with the experimental impedance waveforms recorded on six pairs of adjacent electrodes. The correlation coefficients between each pair of impedance recordings of each subject were always greater than 0.942, showing a mean value of 0.986. This result suggests that the extracranial REG component can be considered as morphologically invariant. On the other hand, negligible phase shifts were observed when mean electrode distances, measured in the blood flow direction, were relatively small, although temporal corrections in the data model would be advisable for longer distances.
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Affiliation(s)
- Juan J Pérez
- Center for Research and Innovation on Bioengineering, Polytechnic University of Valencia, Camino de Vera s/n, 46022 Valencia, Spain.
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