Spectroscopy study of the dynamics of the transencephalic electrical impedance in the perinatal brain during hypoxia
Artikel i vetenskaplig tidskrift, 2005

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.

Cerebral

Asphyxia

Brain

Brain/*physiopathology

Monitoring

Spectrum Analysis

Animals

Oedema

*Electric Impedance

Perinatal

Bioimpedance

Swine

Damage

Hypoxia-Ischemia

Cellular

Brain/*physiology

Författare

Fernando Seoane Martinez

Chalmers, Signaler och system, Signalbehandling och medicinsk teknik, Medicinska signaler och system

Kaj Lindecrantz

Högskolan i Borås

Torsten Olsson

Chalmers, Signaler och system, Signalbehandling och medicinsk teknik, Medicinska signaler och system

Ingemar Kjellmer

Göteborgs universitet

Anders Flisberg

Göteborgs universitet

Ralph Bågenholm

Göteborgs universitet

Physiological Measurement

0967-3334 (ISSN)

Vol. 26 849-863

Ämneskategorier

Medicinsk laboratorie- och mätteknik

MEDICIN OCH HÄLSOVETENSKAP

Biofysik

DOI

10.1088/0967-3334/26/5/021

PubMed

16088073