| 31. |
- Seoane, Fernando, 1976-, et al.
(författare)
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Electrical Bioimpedance Cerebral Monitoring : A Study of the Current Density Distribution and Impedance Sensitivity Maps on a 3D Realistic Head Model
- 2007
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Ingår i: Proceedings of the 3rd IEEE-EMBS International Conference on Neural Engineering. - : IEEE. - 1424407923 ; , s. 256 - 260
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Konferensbidrag (refereegranskat)abstract
- There have been several studies of the application of electrical bioimpedance technology for brain monitoring in the past years. They have targeted a variety of events and injuries e.g. epilepsy or stroke. The current density distribution and the voltage lead field associated with an impedance measurement setup is of critical importance for the proper analysis of any dynamics in the impedance measurement or for an accurate reconstruction of an EIT image, specially a dynamic type. In this work for the first time, the current density distribution is calculated in a human head with anatomical accuracy and resolution down to 1 mm, containing up to 24 tissues and considering the frequency dependency of the conductivity of each tissue. The obtained current densities and the subsequent sensitivity maps are analyzed with a special focus on the dependency of the electrode arrangement and also the measurement frequency. The obtained results provide us with interesting and relevant information to consider in the design of any tool for electrical bioimpedance cerebral monitoring.
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| 32. |
- Seoane, Fernando, et al.
(författare)
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Textile-enabled Instrumentation for Impedance Cardiographic Signals
- 2011
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Research efforts in the areas of Electrical Bioimpedance (EBI) and textile materials with conductive properties have contributed to the proliferation of research projects aiming to test the feasibility of implementing Textile-enabled instrumentation for performing EBI measurements. Most of the work done has been focused on the electrical characterization of the Textrodes (textile electrodes) and on spectroscopy applications of EBI like early detection of Cardiogenic Pulmonary Edema. In this work, a garment composed of two belts containing Textrodes made of conductive Velcro, loops-type, has been manufactured. Both, the abdomen and the neck belts, have four Textrodes connected through a conductive fabric Technik Tex P-130+ Shieldex fabric in pairs. This way, a tetrapolar EBI measurement between the neck and the chest is performed, implementing a typical band electrode arrangement [1] approach with the two belts. Using a custom-made device Respimon that measures the electrical cardiac activity with a 1-lead ECG and a tetrapolar EBI measurement at 50kHz of a portion of the body, and the Textrode garment, the ICG and ECG signals have been recorded and compared with the recordings obtained with Ag/AgCl electrodes placed in the same positions. The resemblance of the ICG and ECG signals obtained with both the Ag/AgCl electrodes and the Textrode garment confirms the feasibility of using Textrodes to perform measurements of cardiac impedance. There are several useful hemodynamic parameters that can be extracted from the ICG signal in combination with the ECG signal. The availability of a Textrode garment, easy to wear and that produces reliable ICG measurements, would contribute to present ICG monitoring as feasible technology for implementing personalized healthcare monitoring systems, especially for e-health applications of heart failure patients management.
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| 37. |
- Thordstein, Magnus, et al.
(författare)
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Effects of inflammation on cerebral electric activity in fetal sheep
- 2008
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Ingår i: 2nd Congress of the European Academy of Paediatrics, Nice 23-28 okt 2008.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- OBJECTIVE Intrauterine infections can by themselves induce fetal brain damage but also potentiate the effects of other harmful influences such as asphyxia and seizures. Using an EEG technique that permits the recording of extremely low frequencies, often called DC EEG, changes in the level, i.e. DC shifts can be detected. The DC level has been suggested to depend mainly on the potential over the blood brain barrier (BBB), in turn decided primarily by the arterial level of pCO2. Fetuses affected by infection/inflammation that produce detrimental effects on the brain, may have elevated levels of pCO2 and disturbance of the BBB. We aimed at investigating the possibility that the DC EEG could be used to detect the effects of inflammation on the fetal brain. METHODS Fetal sheep were instrumented at 97 days of gestation with catheters, four active EEG electrodes placed on the dura mater as well as extracranial reference and ground electrodes. After three days of recovery, the bacterial endotoxin lipopolysaccharide (LPS) was given to the fetus (200 ng i.v.). RESULTS Exposure to LPS induced a positive DC shift in parallel to the assumed affection of cerebral function and to the pCO2 elevation. This change was not always obvious in standard EEG. CONCLUSIONS These recordings of fetal DC EEG appear to be the first to be done. They indicate that the effects of inflammation on cerebral function can be monitored by DC EEG. Such monitoring might be feasible also during late stages of labour and in neonates.
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