Noninvasive measurement of bladder pressure. Does mechanical interruption of the urinary stream inhibit detrusor contraction?

Detrusor underactivity after radical prostatectomy: A prospective observational study

OBJECTIVE

To evaluate the impact of radical prostatectomy (RP) on bladder function with special interest in detrusor underactivity (DU) and to appraise clinical significance of DU in postprostatectomy patients.

MATERIAL AND METHODS

This was a prospective, observational study conducted on male patients subjected to laparoscopic RP (LPR). Urodynamic studies were performed at the day before surgery (visit 1), 3-6 months postoperatively (visit 2) and more than 12 months after surgery (visit 3). Incidence of DU that occurred after LPR (de novo DU), incidence of persisting de novo DU after 12 months, clinical relevance of DU after LPR and predictive factors of de novo DU were assessed.

RESULTS

99 of 100 patients underwent preoperative urodynamic study (visit 1) and those were included in further analysis. 84 and 76 patients were available for follow-up at second and third visit respectively. De novo DU occurred after LPR in 25 (29.7%) patients at visit 2 (p < 0.001). Sixteen from 24 patients (66,7%) who developed de novo DU after RP (visit 2) continued to have DU 1 year after surgery (visit 3) (p = 0.04). On the multivariate analysis, urinary incontinence requiring more than 1 pad per day (odds ratio [OR] 5.11; confidence interval [CI] 1.69-17.19; p = 0.005) and preoperative IPSS storage sub-score (OR 1.25; CI 1.03-1.63; p = 0.030) were significantly associated with de novo DU. Postprostatectomy patients with DU had significantly lower Urinary Assessment of the Expanded Prostate Cancer Index Composite (EPIC) total score (819 vs. 911, p = 0.02), EPIC Function domain score (300 vs. 357, p = 0.002) and EPIC Urinary incontinence domain (137 vs. 224, p = 0.002) when compared to their counterparts without DU.

CONCLUSIONS

RP substantially influences bladder function, causing de novo DU, which persists in substantial number of patients 1 year postoperatively. Furthermore, significant correlation between DU and postprostatectomy urinary incontinence may play a role when anti-incontinence surgery is considered.

ICS-SUFU standard: Theory, terms, and recommendations for pressure-flow studies performance, analysis, and reporting. Part 2: Analysis of PFS, reporting, and diagnosis

AIMS

The Working Group (WG), initiated by the International Continence Society (ICS) Standardisation Steering Committee and supported by the Society of Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction, has revised the ICS Standard for pressure-flow studies of 1997.

METHODS

Based on the ICS standard for developing evidence-based standards, the WG developed this new ICS standard in the period from May 2020 to December 2022. A draft was posted on the ICS website in December 2022 to facilitate public discussion and the comments received have been incorporated into this final release.

RESULTS

The WG has recommended analysis principles for the diagnosis of voiding dysfunction for adult men and women without relevant neurological abnormalities. New standard terms and parameters for objective and continuous grading of urethral resistance (UR), bladder outflow obstruction (BOO) and detrusor voiding contraction (DVC) are introduced in this part 2 of the standard. The WG has summarized the theory and recommendations for the practice of pressure-flow study (PFS) for patients in part 1. A pressure-flow plot is recommended for the diagnosis of every patient, in addition to time-based graphs. Voided percentage and post void residual volume should always be included in PFS analysis and diagnosis. Only parameters that represent the ratio or subtraction of pressure and synchronous flow are recommended to quantify UR and only parameters that combine pressure and flow in a product or sum are recommended to quantify DVC. The ICS BOO index and the ICS detrusor contraction index are introduced in this part 2 as the standard. The WG has suggested clinical PFS dysfunction classes for male and female patients. A pressure-flow scatter graph including every patient's pdet at maximum flow (pdetQmax ) with maximum flow rate (Qmax ) point should be included in all scientific reports considering voiding dysfunction.

CONCLUSION

PFS is the gold standard used to objectively assess voiding function. Quantifying the dysfunction and grading of abnormalities are standardized for adult males and females.

Urinary retention after AdVance™ Sling: A multi-institutional retrospective study

AIMS

To identify risk factors for urinary retention following AdVance™ Sling placement using preoperative urodynamic studies to evaluate bladder contractility.

METHODS

A multi-institutional retrospective review of patients who underwent an AdVance Sling for post-prostatectomy stress urinary incontinence from 2007 to 2019 was performed. Acute urinary retention (AUR) was defined as the complete inability to void or elevated post-void residual (PVR) leading to catheter placement or the initiation of intermittent catheterization at the first void trial postoperatively. Bladder contractility was evaluated based on preoperative urodynamics.

RESULTS

Of the 391 patients in this study, 55 (14.1%) experienced AUR, and 6 patients (1.5%) had chronic urinary retention with a median follow-up of 18.1 months. In total, 303 patients (77.5%) underwent preoperative urodynamics, and there was no significant difference between average PdetQmax (26.4 vs. 27.4 cmH₂ O), Qmax (16.6 vs. 16.2 ml/s), PVR (19.9 vs. 28.1 ml), bladder contractility index (108 vs. 103) for patients with or without AUR following AdVance Sling. Impaired bladder contractility preoperatively was not predictive of AUR. Time to postoperative urethral catheter removal was predictive of AUR (odds ratio, 0.83; 95% confidence interval, 0.73-0.94; p = .003).

CONCLUSIONS

Chronic urinary retention after AdVance Sling placement is uncommon and acute retention is generally self-limiting. No demographic or urodynamic factors were predictive of AUR. Patients who developed AUR were more likely to have their void trials within 2 days following AdVance Sling placement versus longer initial catheterization periods, suggesting that a longer duration of postoperative catheterization may reduce the occurrence of AUR.

The Use of Urodynamics Assessment Before the Surgical Treatment of BPH

Lower urinary tract symptoms (LUTS) are a common problem in men especially with aging. The International Continence Society (ICS) revealed an overall prevalence of LUTS of about two-thirds of men age 40 years and above. The treatment approach depends on accurate determination of the underlying etiology. LUTS is not unique to benign prostate enlargement (BPE) and can be secondary to other causes. In the era where quality of care is important, accurate diagnosis and counseling to meet patients' expectations is of extreme paramount. Thus, proper assessment of patients who present with BPE and LUTS should be an important part of the work up process. Accurate diagnosis and identification of the cause will help to improve quality of treatment, optimize counseling, and improve treatment outcomes. Pressure flow urodynamic studies (PFUDs) are not only important tools that help to identify the underlying causes of LUTS; it is considered the "gold standard" for diagnosis of bladder outlet obstruction (BOO) in patients with enlarged prostate [1, 2]. However, there is a continuous debate on the value of using PFUDs and its association with improved outcomes.

The artificial urinary sphincter and male sling for postprostatectomy incontinence: Which patient should get which procedure?

Surgery is the most efficacious treatment for postprostatectomy incontinence. The ideal surgical approach depends on a variety of patient factors including history of prior incontinence surgery or radiation treatment, bladder contractility, severity of leakage, and patient expectations. Most patients choose to avoid a mechanical device, opting for the male sling over the artificial urinary sphincter. The modern male sling has continued to evolve with respect to device design and surgical technique. Various types of slings address sphincteric incompetence via different mechanisms of action. The recommended surgery, however, must be individualized to the patient based on degree of incontinence, detrusor contractility, and urethral compliance. A thorough urodynamic evaluation is indicated for the majority of patients, and the recommendation for an artificial urinary sphincter, a transobturator sling, or a quadratic sling will depend on urodynamic findings and the patient's particular preference. As advancements in this field evolve, and our understanding of the pathophysiology of incontinence and mechanisms of various devices improves, we expect to see continued evolution in device design.

Surgery for postprostatectomy incontinence: which procedure for which patient?

Surgery remains the most effective treatment for postprostatectomy incontinence. Over the past two decades, this surgery has evolved with respect to both operative technique and sling design, and various devices are now available that have different mechanisms of action, such as the artificial urinary sphincter, retroluminal sling or quadratic sling. The choice of device, however, should be individualized according to the circumstances of each patient. The optimal surgical treatment depends on a variety of patient-related factors, including the degree of urine leakage as assessed by incontinence pad weight test results, bladder contractility, urethral compliance, history of radiation exposure or prior incontinence surgery, and patient preference--given the choice, most patients opt for a sling procedure over an artificial sphincter to avoid implantation of a mechanical device. Athorough urodynamic evaluation is, therefore, necessary for the majority of patients. An artificial urinary sphincter, retroluminal sling or quadratic sling might be the most appropriate choice for a particular patient, depending on their specific urodynamic findings. Progress in this field continues, and several new devices are in development.

Noninvasive urodynamic evaluation

The longevity of the world's population is increasing, and among male patients, complaints of lower urinary tract symptoms (LUTS) are growing. Testing to diagnose LUTS and to differentiate between the various causes should be quick, easy, cheap, specific, not too bothersome for the patient, and noninvasive or minimally so. Urodynamic evaluation is the gold standard for diagnosing bladder outlet obstruction (BOO) but presents some inconveniences such as embarrassment, pain, and dysuria; furthermore, 19% of cases experience urinary retention, macroscopic hematuria, or urinary tract infection. A greater number of resources in the diagnostic armamentarium could increase the opportunity for selecting less invasive tests. A number of groups have risen to this challenge and have formulated and developed ideas and technologies to improve noninvasive methods to diagnosis BOO. These techniques start with flowmetry, an increase in the interest of ultrasound, and finally the performance of urodynamic evaluation without a urethral catheter. Flowmetry is not sufficient for confirming a diagnosis of BOO. Ultrasound of the prostate and the bladder can help to assess BOO noninvasively in all men and can be useful for evaluating the value of BOO at assessment and during treatment of benign prostatic hyperplasia patients in the future. The great advantages of noninvasive urodynamics are as follows: minimal discomfort, minimal risk of urinary tract infection, and low cost. This method can be repeated many times, permitting the evaluation of obstruction during clinical treatment. A urethral connector should be used to diagnose BOO, in evaluation for surgery, and in screening for treatment. In the future, noninvasive urodynamics can be used to identify patients with BOO to initiate early medical treatment and evaluate the results. This approach permits the possibility of performing surgery before detrusor damage occurs.

Maximum isometric detrusor pressure to measure bladder strength in men with postprostatectomy incontinence

OBJECTIVE

To describe the use of isovolumetric detrusor pressure (Piso) in men with postprostatectomy incontinence and compare the rates of detrusor underactivity using Piso versus other common measurements/surrogates of bladder strength.

METHODS

We evaluated 62 men referred to our institution during a 3-year period for workup of postprostatectomy incontinence. During videourodynamic evaluation, the maximum Piso was measured using a mechanical stop test--with the examiner gently occluding the penile urethra during volitional voiding. Statistical analysis was performed to evaluate the effect of patient variables on Piso.

RESULTS

The mean Piso was 54.6 ± 25.4 cm H(2)O. The Piso was <50 cm H(2)O in 40%. Isometric strength did not significantly correlate with age, interval since radical prostatectomy, abdominal leak point pressure, maximal urethral closure pressure, or pad use. The bladder contractility index and other approximations of detrusor underactivity were not predictive of low isometric pressure.

CONCLUSION

Detrusor underactivity is relatively common in men with postprostatectomy incontinence, with 40% demonstrating a Piso <50 cm H(2)O. Our data do suggest, however, that the use of common bladder contractility nomograms, such as the bladder contractility index, might not be appropriate in this population.

The penile cuff test: A clinically useful non-invasive urodynamic investigation to diagnose men with lower urinary tract symptoms

Objectives:

To summarize the development of a novel non-invasive test to categorize voiding dysfunction in men complaining of lower urinary tract symptoms (LUTS) - the penile cuff test.

Methods:

The test involves the controlled inflation of a penile cuff during micturition to interrupt voiding and hence estimate isovolumetric bladder pressure (p_ves.isv). The validity, reliability, and clinical usefulness of the test were determined in a number of studies in men with LUTS.

Results:

The penile cuff test can be successfully performed in over 90% of men with LUTS. The reading of cuff pressure at flow interruption (p_cuff.int) gives a valid and reliable estimate of invasively-measured p_ves.isv and when combined with the reading for maximum flow rate obtained during the test (Q_max) produces an accurate categorization of bladder outlet obstruction (BOO). Use of this categorization prior to treatment allows improved prediction of outcome from prostatectomy.

Conclusion:

The penile cuff test fulfils the criteria as a useful clinical measurement technique applicable to the diagnosis and treatment planning of men with LUTS.

A novel intraurethral device diagnostic index to classify bladder outlet obstruction in men with lower urinary tract symptoms

Objectives. Using a urethral device at the fossa navicularis, bladder pressure during voiding can be estimated by a minimal invasive technique. This study purposes a new diagnostic index for patients with lower urinary tract symptoms (LUTSs). Methods. Fifty one patients presenting with LUTSs were submitted to a conventional urodynamic and a minimal invasive study. The results obtained through the urethral device and invasive classic urodynamics were compared. The existing bladder outlet obstruction index (BOOI) equation that classifies men with LUTSs was modified to allow minimal invasive measurement of isovolumetric bladder pressure in place of detrusor pressure at maximum urine flow. Accuracy of the new equation for classifying obstruction was then tested in this group of men. Results. The modified equation identified men with obstruction with a positive predictive value of 68% and a negative predictive value of 70%, with an overall accuracy of 70%. Conclusions. The proposed equation can accurately classify over 70% of men without resorting to invasive pressure flow studies. We must now evaluate the usefulness of this classification for the surgical treatment of men with LUTSs.

Variation in invasive and noninvasive measurements of isovolumetric bladder pressure and categorization of obstruction according to bladder volume

PURPOSE

We developed a noninvasive test that provides an estimate of isovolumetric bladder pressure by measuring the pressure required to interrupt voiding using controlled inflation of a penile cuff. We noted variation in serial measurements obtained during a single void and, therefore, we determined whether this represents variation in detrusor contraction strength, as predicted in previous studies, or measurement error.

MATERIALS AND METHODS

A total of 36 symptomatic men underwent simultaneous invasive and noninvasive pressure flow studies. Corresponding values of isovolumetric bladder pressure and cuff interruption pressure were recorded at each flow interruption and grouped according to bladder volume to calculate measurement error and bias at various points during a void. Individual variation in the 2 measurements across a range of normalized bladder volumes was then examined using ANOVA.

RESULTS

Cuff interruption pressure showed a consistent level of accuracy as an estimate of isovolumetric bladder pressure across a range of volumes. There were similar, statistically significant differences in isovolumetric bladder pressure and cuff interruption pressure recorded at specific volume increments with the highest values seen in the mid range and the lowest seen at lower bladder volumes (each p <0.01). When plotting, the maximum recorded value of cuff interruption pressure in each individual on our proposed noninvasive pressure flow nomogram provided the best diagnostic accuracy for obstruction.

CONCLUSIONS

This study shows that cuff interruption pressure varies in the expected manner with bladder volume and provides a consistent estimate of isovolumetric bladder pressure throughout a void. These data provide important guidance for interpreting noninvasive pressure flow studies and classifying obstruction on the proposed nomogram.

Aferição simultânea da pressão abdominal na avaliação ultra-sonográfica de mulheres com incontinência urinária de esforço

OBJETIVO: Determinar a influência da aferição da pressão intra-abdominal na avaliação ultra-sonográfica da junção uretrovesical (JUV) e da uretra proximal (UP) em pacientes com incontinência urinária de esforço (IUE). MATERIAIS E MÉTODOS: Estudo prospectivo de corte transversal realizado na Unidade de Pesquisa em Incontinência Urinária da Universidade Federal de Pernambuco, de janeiro de 2002 a janeiro de 2005. Trinta e seis pacientes com queixas de IUE foram submetidas a ultra-sonografia perineal para avaliação da JUV e da UP com a bexiga praticamente vazia (< 50 ml), com aferição simultânea de pressão intra-abdominal. Para as avaliações, foi utilizado aparelho de ultra-som com transdutor vaginal de 7 MHz e seletor eletrônico de mensuração de imagem real, equipado com computador e câmera fotográfica de resolução instantânea. Para a medida da pressão intra-abdominal, foi utilizado aparelho de urodinâmica com cateter de 10 fr retal acoplado a um balão de sensor para medida da pressão intra-abdominal. RESULTADOS: As pacientes tinham idade entre 25 e 69 anos (média de 46,4 ± 10,2 anos). À manobra de Valsalva, a pressão intra-abdominal variou entre 7 cmH2O e 193 cmH2O (média de 99,3 ± 51,8 cmH2O; mediana de 99,5 cmH2O). Oito das 31 (25,8%) pacientes com hipermobilidade da JUV apresentaram pressão intra-abdominal inferior a 60 cmH2O. Não foi detectada relação estatisticamente significante entre a variação de pressão intra-abdominal e os parâmetros ultra-sonográficos em questão. CONCLUSÃO: Há um índice específico de pressão de deslocamento uretral para cada mulher com IUE. Porém, não há associação significativa entre o aumento de pressão intra-abdominal e aumento de mobilidade da JUV e UP em mulheres com quadro clínico de IUE.

Stop test or pressure-flow study? Measuring detrusor contractility in older females

AIMS

Impaired detrusor contractility is common in older adults. One aspect, detrusor contraction strength during voiding, can be measured by the isovolumetric detrusor pressure attained if flow is interrupted mechanically (a stop test). Because interruption is awkward in practice, however, simple indices or nomograms based on measurements made during uninterrupted voiding are an appealing alternative. We investigated whether such methods, originally developed for males, might be applicable in female subjects, and attempted to identify a single best method.

METHODS

We compared stop-test isovolumetric pressures with estimates based on pressure-flow studies in a group of elderly women suffering from urge incontinence. Measurements were made pre- and post-treatment with placebo or oxybutynin, allowing investigation of test-retest reliability and responsiveness to small changes of contractility.

RESULTS

Existing methods of estimating detrusor contraction strength from pressure-flow studies, including the Schäfer contractility nomogram and the projected isovolumetric pressure PIP, greatly overestimate the isovolumetric pressure in these female patients. A simple modification provides a more reliable estimate, PIP(1), equal to p(det.Qmax) + Q(max) (with pressure in cmH(2)O and Q(max) in ml/sec). Typically PIP(1) ranges from 30 to 75 cmH(2)O in this population of elderly urge-incontinent women. PIP(1), however, is less responsive to a small change in contraction strength than the isovolumetric pressure measured by mechanical interruption.

CONCLUSIONS

The parameter PIP(1) is simple to calculate from a standard pressure-flow study and may be useful for clinical assessment of detrusor contraction strength in older females. For research, however, a mechanical stop test still remains the most reliable and responsive method. The Schäfer contractility nomogram and related parameters such as DECO and BCI are not suitable for use in older women.