P1DH.14 - Continuous Non-Invasive Sodium Monitoring in Extracorporeal Circuits

17th International Meeting on Chemical Sensors - IMCS 2018
2018-07-15 - 2018-07-19
Vienna, Austria
P-1 - Sensors for Diagnostics and Healthcare
M. Berger, D. Niebuhr, M. Allers, S. Zimmermann - Leibniz Universität Hannover, Institute of Electrical Engineering and Measurement Technology, Department of Sensors and Measurement Technology, Hannover (Germany)
683 - 684


Dialysis is a blood purification therapy indicated by kidney failure, where blood is pumped via an extracorporeal circuit into a dialyzer consisting of a semi-permeable membrane separating blood and the dialysate. Due to the concentration gradients across this membrane, toxins can be removed from the blood by diffusion and the electrolyte balance can be regulated [1]. However, excessive changes of osmotic substances such as electrolytes can be critical. For instance, a rapid or excessive loss of sodium in blood, and thus a drop in plasma osmolarity, can cause overhydrating of cells, cardiovascular instability and disequilibrium syndrome with headache, muscle cramps and fatigue symptoms. On the other hand, an inefficient loss of sodium can cause increased thirst, hypertension and risk of pulmonary edema [2–5]. Especially for critically ill patients with acute kidney injury, any additional stress during dialysis has to be avoided. A dialysate with individually adjusted electrolytic concentration can prevent such complications. Thus, it is necessary to monitor the plasma electrolyte concentrations and other osmotic substances during dialysis treatment [6]. However, the required hemocompatibility is often difficult with invasive in-line measurement methods [7]. In this work, we present a new approach to non-invasively monitor sodium based on a differential transformer. The output voltage of this transformer depends on the conductivity of the medium [8]. First measurements show a linear correlation between sodium concentration and output voltage.