Urine output is a vital parameter to gauge kidney health. Current monitoring
methods include manually written records, invasive urinary catheterization or
ultrasound measurements performed by highly skilled personnel. Catheterization
bears high risks of infection while intermittent ultrasound measures and manual
recording are time consuming and might miss early signs of kidney malfunction.
Bioimpedance (BI) measurements may serve as a non-invasive alternative for
measuring urine volume in vivo. However, limited robustness have prevented its
clinical translation. Here, a deep learning-based algorithm is presented that
processes the local BI of the lower abdomen and suppresses artefacts to measure
the bladder volume quantitatively, non-invasively and without the continuous
need for additional personnel. A tetrapolar BI wearable system called ANUVIS
was used to collect continuous bladder volume data from three healthy subjects
to demonstrate feasibility of operation, while clinical gold standards of
urodynamic (n=6) and uroflowmetry tests (n=8) provided the ground truth.
Optimized location for electrode placement and a model for the change in BI
with changing bladder volume is deduced. The average error for full bladder
volume estimation and for residual volume estimation was -29 +/-87.6 ml, thus,
comparable to commercial portable ultrasound devices (Bland Altman analysis
showed a bias of -5.2 ml with LoA between 119.7 ml to -130.1 ml), while
providing the additional benefit of hands-free, non-invasive, and continuous
bladder volume estimation. The combination of the wearable BI sensor node and
the presented algorithm provides an attractive alternative to current standard
of care with potential benefits in providing insights into kidney function.