Are rhythmic bladder contractions affected by fill rate and bladder work in neurogenic bladders

Area of Science:

• Urology
• Biomedical Engineering
• Data Analysis

Background:

• Rhythmic bladder contractions (RBCs) are common in neurogenic bladders (NB) during urodynamic studies (UDS).
• RBCs may contribute to bladder hypertrophy despite low pressures, necessitating objective quantification.
• Current methods lack precise characterization of intrinsic bladder activity.

Purpose of the Study:

• To validate Fast Fourier Transform (FFT) analysis for characterizing RBCs in NB patients.
• To assess the relationship between FFT-derived measures and visual inspection.
• To evaluate the stability of FFT analysis across varying bladder filling rates and motion artifacts.

Main Methods:

• Retrospective analysis of 115 UDS from 70 NB patients (0.5-18 years).
• Application of Python-based FFT to detrusor pressure data to derive Highest Amplitude Frequency (HAF).
• Comparison of HAF reproducibility across same-day studies with varying filling rates; statistical evaluation using Bayes Factor, Bland Altman, and ROC analyses.

Main Results:

• HAF demonstrated high reproducibility (r = 0.85) and consistency across same-day UDS, independent of filling rate.
• FFT-derived HAF closely aligned with visually measured frequency (mean difference ~5%).
• ROC analysis established amplitude cutoffs for contraction detection, showing FFT's efficacy in noise reduction.

Conclusions:

• FFT analysis provides a reliable, objective, and reproducible method for quantifying bladder rhythmic activity.
• The derived HAF is a stable parameter, unaffected by filling rate or movement.
• HAF is proposed as a robust urodynamic parameter for objective monitoring of neurogenic bladders.