Recommended Measurement Positions for Urine Volume Estimation via Conductivity Analysis

Abstract

Urinary bladder dysfunction, characterized by the inability to control bladder muscles or perceive bladder fullness accurately, significantly impacts the quality of life and poses risks such as infections or urethral injury due to overfilling. Clean intermittent catheterization (CIC) is commonly used to manage bladder emptying but carries risks like urinary tract infections and urethral damage. Non-invasive monitoring of bladder volume can reduce the need for CIC and associated risks. Conductivity measurement is an alternative technique for estimating bladder volume by analyzing impedance changes. However, the electrode positions for measuring the conductivity in the previous studies are performed at the abdomen where this position could be affected by the intestine or the uterus. In this study, eight electrode positions were investigated including the front, back, and sides. A method to compute the total response utilizing the measurement voltage from the front and the back positions is also proposed. Six bladder sizes, ranging from 164 mm³ to 417 mm³, were simulated, and voltage responses to the volume change were determined. Results indicate that electrode placement and the enlargement of the bladder significantly affect the amplitude and the correlation between the voltage and the bladder volume. The front positions provided the highest amplitude but were unable to sense in some cases. The back, left, and right positions provided good response but were inferior in response linearity. However, the proposed total voltage could effectively reflect the volume while the linearity was significantly improved.