Monitoring body fluid shifts during haemodialysis (HD) using electrical bioimpedance measurments

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. About 25% of patients who need haemodialysis treatment experience acute complications (haemodynamic instability) during the treatment sessions. These instabilities are related to the excess shift of fluids between the extracellular (ECW) and intracellular (ICW) spaces as shown in several publications during the past 10 years. The transcellular fluid shits during haemodialysis are not yet understood. 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. For this purpose a measurement system was developed for the measurement of the body fluid compartments during haemodialysis sessions. Clinical measurements were done using 10 HD patients during 60 HD sessions. Bioimpedance data, arterial blood pressure, blood volume and blood heamatocrit variations were recorded continuously during the HD sessions. Significant decrease in the ECW volumes were recorded during HD session for all patients, however ICW variations were not similar in all patients.