Detection of Cell Morphological Changes of Ischemic Rabbit Liver Tissue Using Bioimpedance Spectroscopy.

Bioimpedance spectroscopy is a promising method for tissue ischemia monitoring; it is used in this research to study ischemia and cell morphology using bioimpedance measurements of rabbit liver tissue. This paper presents the evolution of Cole parameters and cell parameters with time and establishes a relation between cellular morphological changes during cell ischemia with bioimpedance measurements at different frequencies. The general behavior of ischemic liver tissue has been analyzed. Evolution of Cole parameters was extrapolated from BIS measurements, and their behavior was studied with respect to time. Then, cell parameters were estimated from Cole parameters. A detailed analysis of the changes of cell parameters was done in parallel with explanations for these changes depending on the physiological mechanism of ischemia and necrosis bioprocess. These explanations give a confirmation of the established relation between cell morphological changes and the corresponding BIS measurements.

Monitoring Cole-Cole parameters during haemodialysis (HD).

UNLABELLED: The investigation of the hydration process during the haemodialysis treatment sessions is very important for the development of methods for predicting the unbalanced fluid shifts and hypotension crisis hence improving the quality of the haemodialysis procedure. Bioimpedance measurements can give valuable information about the tissue under measurement, therefore characterizing the tissue. In this work we propose a non-invasive method based on local multifrequency bioimpedance measurements that allow us to determine the fluid distribution and variations during haemodialysis. METHODS: Clinical measurements were done using 10 HD patients during 60 HD sessions. Bioimpedance data, ultrafiltration volume, blood volume and blood heamatocrit variations were recorded continuously during the HD sessions. Bioimpedance of the local tissue was measured with a 4-elctrode impedance system using surface electrodes with sampling rate of 1meas./4min. at 6 different frequencies. The measured impedances were fitted into Cole-Cole model and the Cole-Cole parameters were continuously determined for each measurement point during the HD session. ANALYSIS: The 4 Cole-Cole parameters (R 00, R 0, Fc,alpha) and their variations were evaluated. Impedance values at infinite and zero (R 00, R 0) frequencies were extrapolated from Cole-Cole mathematical model. These values are assumed to represent the impedance of total tissue fluid and the impedance of the extracellular space respectively.