Tissue electrical properties monitoring for the prevention of pressure sore

Background: Pressure sores are a significant problem in the healthcare sector. Although they may cause considerable morbidity, they are preventable. Objectives: The objectives of this study are to (1) investigate the electrical properties of a tissue close to and away from the pressure sore site, and (2) establish a new approach for objective, reliable, low-cost and noninvasive screening or detection of pressure sore in its early stage. Study Design: Randomised controlled trial. Methods: Fifteen patients participated in this study. They all had stage I or stage II sacral pressure sores. Tiny surface electrodes in four-electrode configuration were used for all tissue electrical properties measurements recorded over the frequency range of 30-10 MHz. Results: Intraclass correlation coefficient (ICC) showed that all measurements (ICC > 0.90 for all measurements) had good reliability and validity. The real part of impedance (R) and the imaginary part of impedance (X) of a tissue measured close to the pressure sore site was found to be significantly smaller (p < 0.05 in all cases) than that measured away from the pressure sore site at a specific frequency range (R:30.00-38.55 Hz; X:43.95-606.40 Hz). It was also found that the extracellular resistance (R-e) and the ratio of extracellular resistance to intracellular resistance (R-e/R-i) of a tissue measured close to the pressure sore site were significantly smaller (p < 0.05 in all cases) than that measured away from the pressure sore site. Conclusions: Since the electrical properties (R, X, R-e, R-e/R-i) of a tissue close to, and away from, the pressure sore site can be significantly distinguished, a potentially promising method for the screening of pressure sores at an early stage has been proposed.