Frequency Analysis of Bioimpedance Signals Applied to the Field of Urology: A Pilot Study

Abstract

Currently, urodynamics is the technique used for monitoring bladder volume, as it allows the diagnosis of various bladder pathologies such as neurogenic bladder dysfunction. This technique has limitations, including invasiveness and limited ability to detect dynamic changes. Electrical bioimpedance (EBI) emerges as a non-invasive alternative that measures changes in the electrical impedance of biological tissue in response to variations in bladder volume and composition. In this study, a frequency analysis was proposed to identify and compare changes between voided and full bladder using the EBI technique. Bladder filling was monitored in a group of 5 healthy participants by measuring the EBI vector parameters at a frequency of 50 kHz using two pairs of surface electrodes (Ag/AgCl Ambiderm T125). The data at the beginning and end of the measurement were converted to the frequency domain using the Fourier transform, thereby obtaining the frequency spectra. The dominant harmonic in the frequency signals was identified by applying a Gaussian mask, which allowed for filtering the signals and detecting significant patterns and characteristics in bladder impedance. A decrease in the amplitude of the signals was observed after filling, which could indicate a reduction in the reactivity of bladder tissue to electrical stimuli as the bladder fills. With these results, we can conclude that EBI, combined with frequency analysis, allows for the characterization of bladder filling, offering a non-invasive and detailed alternative for monitoring bladder function, with the potential to improve the diagnosis and management of bladder pathologies.