Surface Potential Simulation for Robust Electrode Placement by MRI Based Human Phantom with FEM Based Quasi-Static...

Estimating cardiac output (CO) and thoracic fluid content (TFC) by non-invasive measurement of thoracic electrical bioimpedance (TEB) is on the rise of becoming clinically established. Dynamic fluid management and detecting and trending excess quasi-static thoracic fluids are of particular interest to benefit the critically ill patient. While the advantages such as easy application and non-invasive assessment are intriguing, there are some challenges. In addition to artifacts due to the patient's movement, instability of the electrode-skin interfaces, the accuracy of the applied current and varying cable capacity because of motion, exact placement of electrodes - or lack thereof - must be considered. In particular the robustness of the electrode placement, i.e., the insensitivity to inaccuracy of electrode placement (actual sensor from the nominal). We propose a new technique for evaluation of electrode placement by simulation with MRI based human phantoms with FEM based quasi-static solver for bioimpedance measurement. Results: We identified alternative electrode positions which lead to an increase in robustness of bioimpedance measurements of up to 9.5 times compared to the standard electrode placement. Simulations suggested an improvement in ECG signal quality which was confirmed by a subject measurement.