Electrical impedance of biological matter is known as electrical bio-impedance or simply as bio-impedance. Bio-impedance devices are of great value for monitoring the pathological and physiological status of biological tissues in clinical and home environments. The technological progress in instrumentation has significantly contributed to the progress that has been observed during the last past decades in impedance spectroscopy and electrical impedance cardiograph. Although bio-impedance is not a physiological parameter, the method enables tissue characterization and functional monitoring and can contribute to the monitoring of the health status of a person. In this paper an inexpensive portable multi frequency impedance cardiograph device based on impedance spectroscopy technique has been developed. By means of this system the basic thoracic impedance range and the heart-action-caused changes of impedance can be measured and the hemodynamic parameters of the heart function can be determined. This system has small size and low current consumption. The impedance cardiograph signals of the electrodes configuration by Sramek, Penney and Qu in this work was measured; compared and summarized. The differences of the measuring method, the schematic circuit diagram, the measurement results and area of application between impedance cardiograph and impedance spectroscopy were discussed and compared. The performance of this sensor-system was evaluated.

Die nicht-invasive Analyse der fetalen Herzratenvariabilität mittels abdominaler Elektrokardiographie stellt eine neue Methode zur Beurteilung des fetalen Zustandes dar. Die Herzratenvariabilität gilt hier als ein sensitives Maß der autonomen Regulation. Bereits mit Beginn der zweiten Schwangerschaftshälfte ist es möglich, über das mütterliche Abdomen ein fetales Elektrokardiogramm abzuleiten und einer Herzratenvariabilitätsanalyse zuzuführen. Das Untersuchungskollektiv dieser Arbeit umfasste Frauen mit frühem vorzeitigem Blasensprung als Modell einer pathologischen Alteration des fetalen Zustandes sowie Frauen mit normalen Schwangerschaften zwischen der 20. und 28. Schwangerschaftswoche. Die technische Umsetzung und Analyse der fetalen Herzratenvariabilität erfolgte in Kooperation mit dem Institut für Biomedizinische Technik der TU Dresden. Insgesamt wurden 25 Datensätze der Auswertung zugeführt. Eine Reifung des autonomen Nervensystems des Feten mit ansteigendem Gestationsalter konnte mittels der Herzratenvariabilitätsanalyse gezeigt werden. Zur Risikostratifizierung der Feten bei frühem vorzeitigem Blasensprung konnten bei der Betrachtung der Herzratenvariabilitätsparameter keine signifikanten Unterschiede zum Normalkollektiv erhoben werden. Die Analyse der Parameter erfolgte hierbei unabhängig von den fetalen Verhaltenszuständen. Es konnte gezeigt werden, dass die nicht-invasive Analyse der Herzratenvariabilitätsanalyse methodisch und technisch in der Lage ist, den Fetalzustand und dessen Alterationen zu erfassen.

Electrical impedance of biological matter is known as electrical bio-impedance or simply as bio-impedance. Bio-impedance devices are of great value for monitoring the pathological and physiological status of biological tissues in clinical and home environments. The technological progress in instrumentation has significantly contributed to the progress that has been observed during the last past decades in impedance spectroscopy and electrical impedance cardiograph. Although bio-impedance is not a physiological parameter, the method enables tissue characterization and functional monitoring and can contribute to the monitoring of the health status of a person. In this paper an inexpensive portable multi frequency impedance cardiograph device based on impedance spectroscopy technique has been developed. By means of this system the basic thoracic impedance range and the heart-action-caused changes of impedance can be measured and the hemodynamic parameters of the heart function can be determined. This system has small size and low current consumption. The impedance cardiograph signals of the electrodes configuration by Sramek, Penney and Qu in this work was measured; compared and summarized. The differences of the measuring method, the schematic circuit diagram, the measurement results and area of application between impedance cardiograph and impedance spectroscopy were discussed and compared. The performance of this sensor-system was evaluated.