Validation of a real-time bladder sensation meter during oral hydration in healthy adults: Repeatability and effects of fill rate and ultrasound probe pressure

Abstract

Objectives: A non-invasive protocol was previously developed using three-dimensional ultrasound and a sensation meter to characterize real-time bladder sensation. This study the protocol by measuring the effects of fill rateand ultrasound probe pressure during oral hydration.

Methods: Healthy volunteers with no urinary symptoms (based on International Consultation on Incontinence Questionnaire on Overactive Bladder surveys) were recruited into an oral hydration study. Throughout two complete fill-void cycles, participants drank 2 L Gatorade G2 (The Gatorade Company, Inc., Chicago, Illinois) and used a touch-screen sensation meter to record real-time bladder sensation (0%-100%). The study was repeated three times, once per week (Visits A, B, and C). In Visits A and B, ultrasound was used to measure bladder volume every 5 minutes. Ultrasound was not used in Visit C except at 100% capacity. Volume data from Visit B were used to estimate volumes throughout the fills in Visit C. Sensation-capacity curves were generated for each fill for comparative analysis.

Results: Ten participants completed three visits (60 total fills). Increased fill rate led to decreased sensation throughout filling, andultrasound probe pressure led to increased sensation. Participants reported higher sensation at low volumes during Fill 1 of Visit A before training with the sensation meter. Sensation curves with intermittent ultrasound showed repeatability for Fill 2 in Visits A and B. Fill rate and ultrasound probe pressure affect real-time bladder sensation during oral hydration.

Conclusions: This study demonstrated repeatability of real-time bladder sensation during a two-fill oral hydration protocol with ultrasound.

Keywords: bladder; micturition; overactive bladder; ultrasound; urodynamics.

FIGURE 1

A, timeline of visits A, B, and C along with two fill–void cycles (fill 1 and 2). B, summary of measured effects and results

FIGURE 2

Sensation meter with start and stop buttons (top), slide bar interface (bottom), and verbal sensory threshold radio buttons (right)

FIGURE 3

Effects of fill rate on bladder sensation–capacity curves A, with and B, without ultrasound. Sensation–capacity curves are shown for fill 1 (solid lines, slower filling) and fill 2 (dashed lines, faster filling). Increased fill rate led to decreased sensation (right shift) from 5% to 95% of capacity (P < 0.002; green-shaded regions; area under curve analysis; n = 10)

FIGURE 4

Effects of ultrasound probe pressure on bladder sensation–capacity curves at A, slower and B, faster fill rates. Sensation–capacity curves are shown for filling with (orange lines) and without (gray lines) ultrasound. A, ultrasound probe pressure led to increased sensation (left shift) from 5% to 95% of capacity during slower filling (P = 0.0309; green-shaded region; area under curve analysis; n = 10). B, a similar increase in sensation (left shift) due ultrasound probe pressure was observed during faster filling, and this effect approached statistical significance from 45% to 85% of capacity (P = 0.0526; yellow-shaded region; n = 10)

FIGURE 5

Effect of training on bladder sensation in Fill 1 (A, solid lines) and Fill 2 (B, dashed lines). Sensation–capacity curves are shown for the pretrained visit (blue lines) and the post-trained visit (orange lines). A, higher sensation was reported from 5% to 10% of capacity when participants were untrained or inexperienced with the sensation meter (P = 0.0485; green-shaded region; area under curve analysis; n = 10). B. Sensation–capacity curves for fill 2 were not different before and after training

FIGURE 6

Sensation–capacity curves for all visits and fills. Sensation–capacity curves during faster filling with ultrasound (dashed lines, A2 vs B2) were not different