Frequency Analysis of Bioimpedance Variations in Human Bladder during Changes of Urine Volume's States

Abstract

To verify the hypothesis that the variations of bioimpedance can reflect the status of bladder volume during natural bladder filling. We chose 10 healthy, male volunteers by recording different bladder filling stages using bioimpedance and ECG measurement. The signal measurement acquisition device was design by Sun Yat-sen University. Bioimpedance measurement was employed four silver-silver chloride compound electrodes, two of which are stimulating electrodes, and the others are measuring electrodes. Each electrode is attached to the lower abdomen, the mapping position of urinary bladder. Using Fourier analysis, the bioimpedance signals in different stages were analyzed. During natural bladder filling, subjects were asked to report real sensations. Sensations intensity increased with urine volume increase. Bioimpence power spectrum density (PSD) was related with sensation intensity. During natural bladder filling, PSD revealed two parameters with 0.04-0.15 Hz (low frequency, LF), and 0.15-0.4 Hz (high frequency, HF), which were observed under different bladder sensations. In natural bladder filling, the HF spectrum power is increased, in parallel with an inconspicuous change in LF spectrum. With the ECG signal analysis, the reaults revealed spectrum powers were explained by the autonomic nervous regulation. The novel method can assess the states of bladder volume during natural bladder filling.