Electrical Bioimpedance Based Heart Monitoring System
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- Institutt for fysikk 
There is a great need for monitoring devices in the intensive care unit during, and after, cardiac surgery to be able to detect anomalies at an early stage. The techniques used today are good, but limited in di erent ways. This pilot study proposes a new method for monitoring, based on electrical bioimpedance measured with temporary pacemaker electrodes.A four-electrode setup was used for measurements, where CC electrodes were attached to the pericardium, and temporary pacemaker PU electrodes were immersed in the epicardium. Two of the PU electrodes were placed at the right ventricle, and two at the left ventricle. Measurements were done with four di erent PU electrode pairs (configurations). A dog s heart was the measurement object. The experimental interventions were vena cava occlusion, disconnecting respiration, left ventricular ischemia, and left bundle branch block (LBBB). LabVIEW was used for signal processing. The constructed monitor program was based on di erentiation and cross-correlation to detect signal changes due to abnormalities in the heart.Impedance measurements showed distinct periodic characteristics corresponding to the heart motion, and temporary pacemaker electrodes are therefore applicable for four-electrode measurements. The results from the di erent interventions di ered from baseline, but were somewhat ambiguous, and need further analysis. PU electrodes should preferably be placed in areas a ected by the interventions. The constructed monitor program did not show satisfying results, and requires further development before it can be used for monitoring in the intensive care unit.