Seoane Fernando, Lindecrantz Kaj, Olsson Torsten, Kjellmer Ingemar, Flisberg Anders, Bågenholm Ralph
School of Engineering, University College of Borås, Sweden.
Physiol Meas. 2005 Oct;26(5):849-63. doi: 10.1088/0967-3334/26/5/021. Epub 2005 Aug 8.
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.
缺氧/缺血是新生儿脑损伤最常见的原因。每年有成千上万的新生儿患有围产期窒息。细胞在缺氧/缺血期间会经历一种反应机制，以维持细胞活力，并且作为对缺氧/缺血损伤的反应，细胞环境的组成和结构会发生改变。细胞内外离子浓度的变化以及随之而来的细胞毒性水肿、细胞肿胀，改变了构成组织的电学性质。所产生的变化可以使用电阻抗仪器轻松测量。在本文中，我们报告了一项关于缺氧对围产期大脑影响的阻抗谱研究结果。使用四电极法在20kHz至750kHz的频率范围内测量新生仔猪的经脑阻抗，包括电阻和电抗，并将实验结果与细胞肿胀期间细胞悬浮液模拟的数值结果进行比较。实验结果明确了生物电阻抗的频率依赖性，证实了电阻的变化在低频时比高频时更敏感，并表明电抗在缺氧期间有显著变化。实验结果与数值结果之间的相似性证明了将组织建模为细胞悬浮液的有效性，并证实了细胞水肿过程在生物组织电学性质改变中的重要性。对缺氧/缺血对组织生物电性质影响的研究可能会导致基于生物电阻抗技术应用的有用临床工具的开发。
