Automated quantification of low amplitude rhythmic contractions (LARC) during real-world urodynamics identifies a potential detrusor overactivity subgroup.

OBJECTIVES: Detrusor overactivity (DO) is characterized by non-voiding detrusor smooth muscle contractions during the bladder filling phase and often contributes to overactive bladder. In some patients DO is observed as isolated or sporadic contractions, while in others DO is manifested as low amplitude rhythmic contractions (LARC). The aim of this study was to develop an objective method to quantify LARC frequencies and amplitudes in urodynamic studies (UDS) and identify a subgroup DO of patients with LARC. METHODS: An automated Fast Fourier Transform (FFT) algorithm was developed to analyze a 205-second region of interest of retrospectively collected "real-world" UDS ending 30 seconds before voiding. The algorithm was designed to identify the three largest rhythmic amplitude peaks in vesical pressure (Pves) in the 1.75-6 cycle/minute frequency range. These peak Pves amplitudes were analyzed to determine whether they were 1) significant (above baseline Pves activity) and 2) independent (distinct from any in abdominal pressure (Pabd) rhythm). RESULTS: 95 UDS met criteria for inclusion and were analyzed with the FFT algorithm. During a blinded visual analysis, a neurourologist/urodynamicist identified 52/95 (55%) patients as having DO. The FFT algorithm identified significant and independent (S&I) LARC in 14/52 (27%) patients with DO and 0/43 patients (0%) without DO, resulting in 100% specificity and a significant association (Fischer's exact test, p<0.0001). The average slowest S&I LARC frequency in this DO subgroup was 3.20±0.34 cycles/min with an amplitude of 8.40±1.30 cm-H2O. This algorithm can analyze individual UDS in under 5 seconds, allowing real-time interpretation. CONCLUSIONS: An FFT algorithm can be applied to "real-world" UDS to automatically characterize the frequency and amplitude of underlying LARC. This algorithm identified a potential subgroup of DO patients with LARC.

Potential vascular mechanisms in an ex vivo functional pig bladder model.

AIMS: Chronic ischemia is a recognized factor in the pathophysiology of underactive bladder (UAB). Although relative ischemia (ie, low blood flow) is known to occur during filling, little is known regarding the pathophysiology that leads to UAB. Therefore, we developed an ex vivo functional porcine model to investigate the role of transient ischemia and whether autoregulation, a mechanism that maintains tissue oxygenation in certain vital organs, also exists in the bladder. METHODS: Using bladders from slaughtered pigs, we prepared an isolated perfused model where we studied the effects of bladder perfusion flow rate on perfusion pressure and tissue oxygenation during the filling phase. Bladders were perfused at an initial flow rate of 20 mL/min and then clamped in a sequentially decreasing stepwise manner down to no flow and back to the initial flow rate. RESULTS: We found a linear relationship between flow rate and perfusion pressure until the flow rate decreased below 5 mL/min at which point the vascular resistance decreased; however, tissue pO2 remained stable after an initial decline. CONCLUSIONS: These findings suggest that there may be an intrinsic autoregulatory mechanism in the bladder that allows it to undergo cyclic episodes of relative ischemia during its normal function. Factors that overcome this mechanism such as complete or chronic ischemia may be critical in the progression to detrusor underactivity and thereby highlight the importance of intervention during the early phases of this disease process.

Assessment of communication technology and post-operative telephone surveillance during global urology mission.

OBJECTIVE: Compliance with post-operative follow-up in the context of international surgical trips is often poor. The etiology of this problem is multifactorial and includes lack of local physician involvement, transportation costs, and work responsibilities. We aimed to better understand availability of communication technologies within Belize and use this information to improve follow-up after visiting surgical trips to a public hospital in Belize City. Accordingly, a 6-item questionnaire assessing access to communication technologies was completed by all patients undergoing evaluation by a visiting surgical team in 2014. Based on this data, a pilot program for patients undergoing surgery was instituted for subsequent missions (2015-2016) that included a 6-week post-operative telephone interview with a visiting physician located in the United States. RESULTS: Fifty-four (n = 54) patients were assessed via survey with 89% responding that they had a mobile phone. Patients reported less access to home internet (59%), local internet (52%), and email (48%). Of 35 surgical patients undergoing surgery during 2 subsequent surgical trips, 18 (51%) were compliant with telephone interview at 6-week follow-up. Issues were identified in 3 (17%) patients that allowed for physician assistance. The cost per patient interview was $10 USD.

Quantification of bladder wall biomechanics during urodynamics: A methodologic investigation using ultrasound.

Overactive bladder is often characterized by biomechanical changes in the bladder wall, but there is no established method to measure these changes in vivo. The goal of this study was to develop a novel method to determine detrusor wall biomechanical parameters during urodynamics through the incorporation of transabdominal ultrasound imaging. Individuals with overactive bladder (OAB) underwent ultrasound imaging during filling. The fill rate was 10% of the cystometric capacity per minute as determined by an initial fill. Transabdominal ultrasound images were captured in the midsagittal and transverse planes at 1min intervals. Using image data and Pves, detrusor wall tension, stress, and compliance were calculated. From each cross-sectional image, luminal and wall areas along with inner perimeters were measured. In the sagittal and transverse planes, wall tension was calculated as Pves∗luminal area, wall stress as tension/wall area, and strain as the change in perimeter normalized to the perimeter at 10% capacity. Elastic modulus was calculated as stress/strain in the medial-lateral and cranial-caudal directions. Patient-reported fullness sensation was continuously recorded. Data from five individuals with OAB showed that detrusor wall tension, volume, and strain had the highest correlations to continuous bladder sensation of all quantities measured. This study demonstrates how detrusor wall tension, stress, strain, and elastic modulus can be quantified by adding ultrasound imaging to standard urodynamics. This technique may be useful in diagnosing and better understanding the biomechanics involved in OAB and other bladder disorders.

Providing Access to Care through a 24-Hour Dedicated Stone Line.

INTRODUCTION: Many patients with urolithiasis are seen acutely in the emergency department for initial treatment. In an effort to improve cost and quality of care increasing focus has been placed on shifting management of low acuity conditions from emergency departments to outpatient settings. One barrier to such initiatives is timely access to outpatient services. We established a telephone stone line to provide access to outpatient urological care of kidney stones and we report our initial experience. METHODS: A 24-hour dedicated telephone stone line was created with calls answered by dedicated staff. A computer program was created to track stone line calls and post-call care. We retrospectively analyzed all stone line calls received in a 4-year period with the focus on utilization and cost. An e-mail survey was performed to assess patient satisfaction. RESULTS: Between January 2009 and July 2013 the mean call volume was 2,107 per year. A significant distribution of calls was seen across all days and hours. Duration was less than 15 minutes in 7,761 calls (82%). Patients or family members placed 77% of calls and physicians placed 16%. As a result of a stone line call, 4,173 patients (76%) were seen by a urologist within 48 hours. Of the patients 88% reported satisfaction with the stone line. The mean annual cost of providing the telephone stone line was $51,873. CONCLUSIONS: Our experience demonstrates sustained utilization of and satisfaction with the telephone stone line. Further, stone line use results in timely outpatient evaluation in the majority of patients. Further analysis to assess for a cost benefit is ongoing.

Low amplitude rhythmic contraction frequency in human detrusor strips correlates with phasic intravesical pressure waves.

PURPOSE: Low amplitude rhythmic contractions (LARC) occur in detrusor smooth muscle and may play a role in storage disorders such as overactive bladder and detrusor overactivity. The purpose of this study was to determine whether LARC frequencies identified in vitro from strips of human urinary bladder tissue correlate with in vivo LARC frequencies, visualized as phasic intravesical pressure (p ves) waves during urodynamics (UD). METHODS: After IRB approval, fresh strips of human urinary bladder were obtained from patients. LARC was recorded with tissue strips at low tension (<2 g) and analyzed by fast Fourier transform (FFT) to identify LARC signal frequencies. Blinded UD tracings were retrospectively reviewed for signs of LARC on the p ves tracing during filling and were analyzed via FFT. RESULTS: Distinct LARC frequencies were identified in 100% of tissue strips (n = 9) obtained with a mean frequency of 1.97 ± 0.47 cycles/min (33 ± 8 mHz). Out of 100 consecutive UD studies reviewed, 35 visually displayed phasic p ves waves. In 12/35 (34%), real p ves signals were present that were independent of abdominal activity. Average UD LARC frequency was 2.34 ± 0.36 cycles/min (39 ± 6 mHz) which was similar to tissue LARC frequencies (p = 0.50). A majority (83%) of the UD cohort with LARC signals also demonstrated detrusor overactivity. CONCLUSIONS: During UD, a subset of patients displayed phasic p ves waves with a distinct rhythmic frequency similar to the in vitro LARC frequency quantified in human urinary bladder tissue strips. Further refinements of this technique may help identify subsets of individuals with LARC-mediated storage disorders.

Non-invasive characterization of real-time bladder sensation using accelerated hydration and a novel sensation meter: An initial experience.

AIMS: The purpose of this investigation was to develop a non-invasive, objective, and unprompted method to characterize real-time bladder sensation. METHODS: Volunteers with and without overactive bladder (OAB) were prospectively enrolled in a preliminary accelerated hydration study. Participants drank 2L Gatorade-G2® and recorded real-time sensation (0-100% scale) and standardized verbal sensory thresholds using a novel, touch-screen "sensation meter." 3D bladder ultrasound images were recorded throughout fillings for a subset of participants. Sensation data were recorded for two consecutive complete fill-void cycles. RESULTS: Data from 14 normal and 12 OAB participants were obtained (ICIq-OAB-5a = 0 vs. ≥3). Filling duration decreased in fill2 compared to fill1, but volume did not significantly change. In normals, adjacent verbal sensory thresholds (within fill) showed no overlap, and identical thresholds (between fill) were similar, demonstrating effective differentiation between degrees of %bladder capacity. In OAB, within-fill overlaps and between-fill differences were identified. Real-time %capacity-sensation curves left shifted from fill1 to fill2 in normals, consistent with expected viscoelastic behavior, but unexpectedly right shifted in OAB. 3D ultrasound volume data showed that fill rates started slowly and ramped up with variable end points. CONCLUSIONS: This study establishes a non-invasive means to evaluate real-time bladder sensation using a two-fill accelerated hydration protocol and a sensation meter. Verbal thresholds were inconsistent in OAB, and the right shift in OAB %capacity-sensation curve suggests potential biomechanical and/or sensitization changes. This methodology could be used to gain valuable information on different forms of OAB in a completely non-invasive way.

A pilot study to measure dynamic elasticity of the bladder during urodynamics.

AIMS: Previous studies using isolated strips of human detrusor muscle identified adjustable preload tension, a novel mechanism that acutely regulates detrusor wall tension. The purpose of this investigation was to develop a method to identify a correlate measure of adjustable preload tension during urodynamics. METHODS: Patients reporting urgency most or all of the time based on ICIq-OAB survey scores were prospectively enrolled in an extended repeat fill-and-empty urodynamics study designed to identify a correlate of adjustable preload tension which we now call "dynamic elasticity." Cystometric capacity was determined during initial fill. Repeat fills to defined percentages of capacity with passive emptying (via syringe aspiration) were performed to strain soften the bladder. A complete fill with active voiding was included to determine whether human bladder exhibits reversible strain softening. RESULTS: Five patients completed the extended urodynamics study. Intravesical pressure (pves ) decreased with subsequent fills and was significantly lower during Fill 3 compared to Fill 1 (P = 0.008), demonstrating strain softening. Active voiding after Fill 3 caused strain softening reversal, with pves in Fill 4 returning to the baseline measured during Fill 1 (P = 0.29). Dynamic elasticity, the urodynamic correlate of adjustable preload tension, was calculated as the amount of strain softening (or its reversal) per %capacity (Δaverage pves between fills/Δ%capacity). Dynamic elasticity was lost via repeat passive filling and emptying (strain softening) and regained after active voiding regulated the process (strain softening reversal). CONCLUSIONS: Improved understanding of dynamic elasticity in the human bladder could lead to both improved sub-typing and novel treatments of overactive bladder. Neurourol. Urodynam. 36:1086-1090, 2017. © 2016 Wiley Periodicals, Inc.

Long-Term Outcomes After Repair of Transurethral Perforation of Midurethral Sling.

OBJECTIVES: The literature lacks long-term evaluation of outcomes after repair of transurethral midurethral sling (MUS) perforation. METHODS: We prospectively followed 5 patients undergoing repair of urethral perforation (International Continence Society-International Urogynecological Association classification 4B) after MUS (mean follow-up, 54 months). Outcomes assessment was composed of validated measures of urinary (International Consultation on Incontinence Questionnaire [ICIQ]-Female Lower Urinary Tract Symptoms), vaginal (ICIQ-Vaginal Symptoms), and quality of life (Incontinence Impact Questionnaire, Short Form) symptoms. RESULTS: Five patients underwent MUS (4 transobturator, 1 retropubic) with a mean of 41 months before referral. Primary referring complaints composed of hematuria (2), weak stream (2), and urgency (1). All but 1 patient reported transient urinary retention requiring catheterization after initial sling placement. Each patient underwent transvaginal sling excision and repair of urethral injury. Four of 5 patients experienced persistent postoperative stress urinary incontinence. Before final assessment, further treatment included observation, physical therapy, and autologous fascial sling in 1, 2, and 2 patients, respectively. ICIQ-Female Lower Urinary Tract Symptoms, ICIQ-Vaginal Symptoms, and Incontinence Impact Questionnaire, Short Form, assessment failed to demonstrate statistically significant improvements in comparison of baseline and multiple time point (6-week, 12-month, 54-month) assessments during long-term follow-up (P > 0.05). CONCLUSIONS: Urethral perforation represents a significant complication after MUS placement. Many patients continue to have incontinence despite the use of physical therapy/salvage sling placement. Furthermore, subjective outcomes and quality of life do not seem to improve over time. Because of the rarity of urethral perforation, our small series is notable given the absence of reported data that include prospective, long-term follow-up with validated questionnaire evaluation.

Acute length adaptation and adjustable preload in the human detrusor.

AIMS: The biomechanical properties of length adaptation and adjustable preload have been previously identified in detrusor smooth muscle in animal models. This in vitro study aims to show that human detrusor smooth muscle exhibits length adaptation and adjustable preload tension which could play an important role in both overactive bladder and detrusor underactivity. METHODS: In order to demonstrate length adaptation, human detrusor smooth muscle strips are stretched and contracted beyond an optimum length and then contracted three times at the previous optimum length to determine if maximum active tension could be re-established. To demonstrate adjustable preload (Tap ), human detrusor smooth muscle strips are subjected to a pre-defined loading-unloading (strain softening) sequence to reduce preload. Then, tissues are contracted and the sequence is repeated to determine if this active process restored preload. RESULTS: Nine patients (average age, 62) provide tissue: 89% are men with urothelial carcinoma and a minority (22%) also have neurogenic bladder dysfunction. In the length adaptation protocol, contractions show progressive increases in active tension (P < 0.05). In the Tap protocol, a significant amount of preload is lost to strain softening (P < 0.05) and is restored after active contraction (P = 0.50). Exposure to the rho-kinase inhibitor, H-1152, prevents the restoration of preload (P < 0.05). CONCLUSIONS: This study demonstrates that human detrusor smooth muscle displays both length adaptation and Tap . Furthermore, Tap may be regulatable through a rho-kinase pathway. These biomechanical processes may be important in the pathophysiology of both overactive bladder and detrusor underactivity. Neurourol. Urodynam. 35:792-797, 2016. © 2015 Wiley Periodicals, Inc.

Reproduction of Female Lower Urinary Tract Symptoms on Urodynamics.

OBJECTIVES: Urodynamic testing (UDS) can be a valuable tool in the assessment of urinary incontinence and voiding dysfunction. The success of UDS in reproducing patients' symptoms has not been well defined. We sought to determine the ability of UDS to reliably reproduce various lower urinary tract symptoms and secondarily the ability of UDS to produce disparate findings not associated with patients presenting symptoms. METHODS: Following Institutional Review Board approval, patient data was accumulated prospectively over 10 months. Notation was made of primary and secondary symptoms as well as if these stated symptoms were reproduced during the urodynamic procedure. Presenting lower urinary tract symptoms included for analysis were stress, mixed and urge incontinence, urgency, and obstructive symptoms. We also reviewed the number of disparate urodynamic observations that did not correlate with patient history. RESULTS: Over a 10-month period, 127 women had interpretable data with respect to whether their presenting symptoms were reproduced during UDS. Presenting symptoms were successfully reproduced on 83% of UDS studies. Disparate urodynamic observations were noted in 60% of patients. CONCLUSIONS: Reproduction of patient symptoms during UDS occurred in the majority of cases if the patient was queried regarding this association. Additional disparate urodynamic observations were also noted in a majority of patients undergoing UDS. It remains unclear whether reproduction of symptoms during UDS in females ultimately results in improved interventional outcomes. The implications of new or unexpected UDS findings during UDS are unknown.