Performance of Novel Patient Interface for Electrical Impedance Tomography Applications

In electrical impedance tomography (EIT) currents are applied to a body, for example to the human thorax, and resulting voltages are measured to estimate the intra-thoracic impedance distribution. For this purpose 16 or 32 individual electrodes need to be placed onto the patient. The electrical contact with skin is one of the most important performance factors for EIT measurements. In this study, the electrical skin contact of a novel, textile-based electrode assembly comprising 32 active electrodes integrated in a vest-like structure was assessed in 10 volunteers and in 40 patients. Skin contact impedance was measured with dry and wetted electrodes; mid-term stability was measured over a period of 4 h. Results showed that the skin contact impedance of the dry electrodes was higher than 2 kΩ at a frequency of 144 kHz, after applying contact agent, the skin contact impedance dropped below 500 Ω and remained there for the next 4 h. We conclude that the new patient interface in combination with the special contact agent provides a stable electrical contact between electrodes and skin for at least 4 h.