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Electrical Bioimpedance Cerebral Monitoring: Effects of Hypoxia
University of Borås. (Medical Electronics)ORCID iD: 0000-0002-6995-967X
2005 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Electrical bioimpedance spectroscopy is one way to study the electrical properties of biological matter. Different applications of electrical bioimpedance measurements have already been used in both research and clinical scenarios i.e. impedance plethysmography, total body water contents, etc. The electrical properties of tissue reflect the electrical characteristics of the constituent elements of the tissue and depend on its structure. Thus study of the electrical properties not only makes it possible to differentiate among tissues but also to determine the tissue condition. During hypoxia/ischemia the cell activates a certain chain of mechanisms of cellular adaptation in response to the insult. A consequence of these response mechanisms is that the biochemical composition of the cellular environment is altered and the cells swell (cellular edema). These alterations affect the electrical properties of tissue and the changes can be observed through measurement of the electrical bioimpedance of the affected tissue. Based on these ideas, this research work studies the effects of hypoxia/ischemia on the brain electrical impedance. The aim is to obtain the fundamental knowledge that may lead to the development of useful clinical tools for cerebral monitoring based on electrical bioimpedance spectroscopy. 

Place, publisher, year, edition, pages
Gothenburg: Chalmers Reproservice , 2005. , 84 p.
Series
Chalmers Technical Reports, ISSN 1403-266X ; R012/2005
National Category
Medical Laboratory and Measurements Technologies
Identifiers
URN: urn:nbn:se:kth:diva-80373OAI: oai:DiVA.org:kth-80373DiVA: diva2:496271
Presentation
2015-04-17, EA4, Gothenburg, 13:00 (English)
Opponent
Supervisors
Projects
Brain damage, Detection and localization of cell swelling
Note
QC 20120217Available from: 2012-02-17 Created: 2012-02-09 Last updated: 2012-02-17Bibliographically approved
List of papers
1. Evolution of Cerebral Bioelectrical Resistance at Various Frequencies During Hypoxia in Fetal Sheep
Open this publication in new window or tab >>Evolution of Cerebral Bioelectrical Resistance at Various Frequencies During Hypoxia in Fetal Sheep
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2004 (English)In: Australasian Physical & Engineering Sciences in Medicine, ISSN 0158-9938, Vol. 27, no 4Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Springer, 2004
National Category
Medical Laboratory and Measurements Technologies Neurology
Identifiers
urn:nbn:se:kth:diva-73198 (URN)0158-9938 (ISBN)
Conference
Engineering and Physical Sciences in Medicine
Note

QC 20160916

Available from: 2012-02-01 Created: 2012-02-01 Last updated: 2016-09-16Bibliographically approved
2. Bioelectrical Impedance During Hypoxic Cell Swelling: Modeling of Tissue as a Suspension of Cells
Open this publication in new window or tab >>Bioelectrical Impedance During Hypoxic Cell Swelling: Modeling of Tissue as a Suspension of Cells
2004 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Non-invasive multi-frequency measurements of transcephalic impedance, both reactance and resistance, can efficiently detect cytotoxic edema in brain tissue and can be used for early detection of threatening brain damage. The model of biological tissue as a suspension of cells can be used as a valuable guide to identify the optimum range of frequencies for electrical impedance monitoring to detect cell swelling efficiently. We have performed experiments on piglets to monitor transcephalic impedance during hypoxia. The obtained results have confirmed the hypothesis that changes in the size of cells modify the tissue impedance. During tissue inflammation after induced hypoxia, cerebral tissue exhibits changes in both reactance and resistance. Those changes in impedance exhibit certain dependency of frequency in concordance with the suspension of cells model. The experimentally observed changes are remarkably high, up to 71% over the baseline, and easy to measure especially at certain frequencies. A better understanding of the electrical behaviour of cerebral tissue during cell swelling may lead the development effective non-invasive clinical tools and methods for early diagnosis of cerebral edema and brain damage prevention.

Place, publisher, year, edition, pages
Gdansk: , 2004
Keyword
Bio-impedance, Brain Damage, Cell Swelling, Cerebral Edema, Cole Plot, Hypoxia, Ischemia, Suspension of Cells, Tissue inflammation
National Category
Medical Laboratory and Measurements Technologies Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-73195 (URN)83-917681-6-3 (ISBN)
Conference
XII International Conference on Electrical Bioimpedance & V Electrical Impedance Tomography
Note
QC 20120206Available from: 2012-02-06 Created: 2012-02-01 Last updated: 2012-02-17Bibliographically approved
3. Brain electrical impedance at various frequencies: the effect of hypoxia
Open this publication in new window or tab >>Brain electrical impedance at various frequencies: the effect of hypoxia
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2004 (English)In: Proceedings of the 26th Annual International Conference of the IEEE EMBS, San Francisco, CA, USA • September 1-5, 2004, IEEE Engineering in Medicine and Biology Society , 2004, Vol. 3, 2322-2325 p.Conference paper, Published paper (Refereed)
Abstract [en]

Non-invasive multi-frequency measurements of transcephalic impedance, both reactance and resistance, can efficiently detect cell swelling of brain tissue and can be used for early detection of threatening brain damage. We have performed experiments on piglets to monitor transcephalic impedance during hypoxia. The obtained results have confirmed the hypothesis that changes in the size of cells modify the tissue impedance. During tissue inflammation after induced hypoxia, cerebral tissue exhibits changes in both reactance and resistance. Those changes are remarkably high, up to 71% over the baseline, and easy to measure especially at certain frequencies. A better understanding of the electrical behaviour of cerebral tissue during cell swelling would lead us to develop effective non-invasive clinical tools and methods for early diagnosis of cerebral edema and brain damage prevention.

Place, publisher, year, edition, pages
IEEE Engineering in Medicine and Biology Society, 2004
Series
PROCEEDINGS OF ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, ISSN 1094-687X ; 26, part 1-7
Keyword
bio-impedance; brain damage; cell swelling; cerebral edema; hypoxia; ischemia; tissue inflammation
National Category
Medical Laboratory and Measurements Technologies Signal Processing Neurology
Identifiers
urn:nbn:se:kth:diva-73060 (URN)10.1109/IEMBS.2004.1403674 (DOI)000225461800600 ()17272194 (PubMedID)0-7803-8439-3 (ISBN)
Conference
26th Annual International Conference of the IEEE EMBS, San Francisco, CA, SEP 01-05, 2004
Note
Sponsors: Institute of Electrical and Electronics Engineers, IEEE; IEEE Engineering in Medicine and Biology Society. © 2004 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. QC 20120206Available from: 2012-02-06 Created: 2012-02-01 Last updated: 2012-02-17Bibliographically approved
4. Spectroscopy study of the dynamics of the transencephalic electrical impedance in the perinatal brain during hypoxia
Open this publication in new window or tab >>Spectroscopy study of the dynamics of the transencephalic electrical impedance in the perinatal brain during hypoxia
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2005 (English)In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 26, no 5, 849-863 p.Article in journal (Refereed) Published
Abstract [en]

Hypoxia/ischaemia is the most common cause of brain damage in neonates. Thousands of newborn children suffer from perinatal asphyxia every year. The cells go through a response mechanism during hypoxia/ischaemia, to maintain the cellular viability and, as a response to the hypoxic/ischaemic insult, the composition and the structure of the cellular environment are altered. The alterations in the ionic concentration of the intra- and extracellular and the consequent cytotoxic oedema, cell swelling, modify the electrical properties of the constituted tissue. The changes produced can be easily measured using electrical impedance instrumentation. In this paper, we report the results from an impedance spectroscopy study on the effects of the hypoxia on the perinatal brain. The transencephalic impedance, both resistance and reactance, was measured in newborn piglets using the four-electrode method in the frequency range from 20 kHz to 750 kHz and the experimental results were compared with numerical results from a simulation of a suspension of cells during cell swelling. The experimental results make clear the frequency dependence of the bioelectrical impedance, confirm that the variation of resistance is more sensitive at low than at high frequencies and show that the reactance changes substantially during hypoxia. The resemblance between the experimental and numerical results proves the validity of modelling tissue as a suspension of cells and confirms the importance of the cellular oedema process in the alterations of the electrical properties of biological tissue. The study of the effects of hypoxia/ischaemia in the bioelectrical properties of tissue may lead to the development of useful clinical tools based on the application of bioelectrical impedance technology.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2005
Keyword
bioimpedance; brain damage; cellular oedema; cerebral monitoring; perinatal asphyxia
National Category
Neurology Medical Laboratory and Measurements Technologies Signal Processing
Identifiers
urn:nbn:se:kth:diva-73059 (URN)10.1088/0967-3334/26/5/021 (DOI)000232666400022 ()16088073 (PubMedID)
Note
QC 20120208Available from: 2012-02-08 Created: 2012-02-01 Last updated: 2017-12-08Bibliographically approved

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