Monitoring Cole-Cole parameters during haemodialysis (HD).
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.


METHODS
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.
Al-Surkhi
Omar I
OI
Biomedical Engineering Research Center, Technical University of Catalonia UPC, Barcelona Spain. omar@eel.upc.edu
Riu
P J
PJ
Vazquez
F F
FF
Ibeas
J
J
D055592:Biophysical Phenomena; D001703:Biophysics; D001825:Body Fluid Compartments; D001826:Body Fluids; D001835:Body Weight; D017097:Electric Impedance; D004566:Electrodes; D004867:Equipment Design; D006801:Humans; D015233:Models, Statistical; D008962:Models, Theoretical; D006435:Renal Dialysis / Q000295:instrumentation* / Q000379:methods*; D012984:Software; D013997:Time Factors