Feasibility of fluid volume conductance to assess bladder volume

Gill, Bradley C.; Fletter, Paul C.; Zaszczurynski, Paul; Perlin, Alfred; Yachia, Daniel; Damaser, Margot S.

doi:10.1002/nau.20551

Cited by 14 publications

(19 citation statements)

References 35 publications

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“…21 Previous studies examined only the relationship of the amplitude with bladder volume. 8,12,26 Our study is the first to examine whether the phase information might also be useful for predicting bladder volume. Thus, the finding that phase information can help overcome changes in urine conductivity is novel and has high clinical relevance.…”

Section: Discussionmentioning

confidence: 99%

“…This was particularly evident when the volume threshold metric was used (4.24 ± 0.65 mL threshold error, as discussed in the previous paragraph). Variations in urine conductivity have previously been reported to have a significant impact on the performance of impedancebased volume estimation methods, 8 and are considered to be an important obstacle to the robustness of implanted bladder volume estimation devices in a chronic in vivo situation. 21 Previous studies examined only the relationship of the amplitude with bladder volume.…”

Section: Discussionmentioning

confidence: 99%

“…Gill et al previously reported that the performance of an impedance-based bladder volume estimation method (using amplitude) decreased at higher volumes as the relationship became non-linear. 8 It will be crucial to investigate the variations of the phase information for bladder volumes up to the 400-600 mL range and characterize the phase-to-volume relationship in more detail. This will require future studies in larger models.…”

Section: Discussionmentioning

confidence: 99%

“…The effectiveness of electrical impedance plethysmography has further been found to be limited by a number of confounding factors, including electrode placement, the variable conductivity of urine, and body fat. 1,8,12,14,26,32 The previous studies that have examined the electrical impedance of the bladder using implanted electrodes have focused on the resistance component of the impedance. 8,12,26 As the bladder fills with urine and the distance between the electrodes changes, however, it is possible that capacitive effects will also play a role and lead to a change in the reactance component as well.…”

Section: Introductionmentioning

confidence: 99%

“…1,8,12,14,26,32 The previous studies that have examined the electrical impedance of the bladder using implanted electrodes have focused on the resistance component of the impedance. 8,12,26 As the bladder fills with urine and the distance between the electrodes changes, however, it is possible that capacitive effects will also play a role and lead to a change in the reactance component as well. These effects may in turn be manifested as changes in the phase relationships between an injected current sinusoid and the waveforms measured by pairs of recording electrodes on the bladder wall.…”

Section: Introductionmentioning

confidence: 99%

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A Phase-Based Electrical Plethysmography Approach to Bladder Volume Measurement

et al. 2015

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Neuromodulation approaches to treating lower urinary tract dysfunction could be substantially improved by a sensor able to detect when the bladder is full. A number of approaches to this problem have been proposed, but none has been found entirely satisfactory. Electrical plethysmography approaches attempt to relate the electrical impedance of the bladder to its volume, but have previously focused only on the amplitudes of the measured signals. We investigated whether the phase relationships between sinusoidal currents applied through a pair of stimulating electrodes and measured through a pair of recording electrodes could provide information about bladder volume. Acute experiments in a rabbit model were used to investigate how phase-to-volume or amplitude-to-volume regression models could be used to predict bladder volumes in future recordings, with and without changes to the saline conductivity. Volume prediction errors were found to be 6.63 ± 1.12 mL using the phase information and 8.32 ± 3.88 mL using the amplitude information (p = 0.44 when comparing the phase and amplitude results, n = 6), where the volume of the filled bladder was about 25 mL. When a full/empty binary decision rule was applied based on the regression model, the difference between the actual threshold that would result from this rule and the desired threshold was found to be 4.24 ± 0.65 mL using the phase information and 106.92 ± 189.82 mL using the amplitude information (p = 0.03, n = 6). Our results suggest that phase information can form the basis for more effective and robust electrical plethysmography approaches to bladder volume measurement.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%