Urodynamic features and artefacts

Effectiveness of onabotulinumtoxin A for refractory overactive bladder with cough-associated detrusor overactivity

Introduction

We report a case of refractory overactive bladder with cough-associated detrusor overactivity treated by onabotulinumtoxin A.

Case presentation

A 79-year-old woman who underwent mid-urethral sling surgery 8 years ago complained mainly of urinary incontinence following abdominal pressure. Various medicines to treat overactive bladder symptoms were ineffective. Cystometry revealed cough-associated detrusor overactivity. Onabotulinumtoxin A injections in her bladder improved subjective symptoms, and cough-associated detrusor overactivity disappeared on cystometry.

Conclusions

Onabotulinumtoxin A injection effectively resolved refractory overactive bladder with urgency urinary incontinence due to cough-associated detrusor overactivity.

The design and evaluation of a quick checklist for urodynamic quality control: A prospective single-center small sample study

PURPOSE

To design a quick checklist for urodynamic study (UDS), aiming to reduce the occurrence of errors in the process, which may help to increase the quality of UDS. And further to analyze the effectiveness of this quick checklist for UDS quality control.

METHODS

First, a quick checklist for uroflow study and pressure-flow study was developed, based on the International Continence Society-Good Urodynamic Practice standards, our previous studies, and recent literature, as well as expert suggestions. Then, patients who underwent UDS between January 2023 to February 2023 were randomly assigned to a study group or a control group. For the study group, the quick checklist was used throughout the UDS process, while the control group did not. The main artefacts were chosen to verify the effectiveness of the quick checklist for improving the UDS quality.

RESULTS

The quick checklist comprised three subtypes: checklist for patients, checklist for environment and device, and checklist for UDS test process. 38 UDS traces per group were included. The incidence of missing the standard cough test decreased significantly from 18.4% to 0 (p = 0.012), with the checklist implementation. The baseline drift frequency rate also declined significantly from 39.5% to 5.3% (p < 0.05). Volume < 150 mL on uroflow study occurred in 68.4% of cases and its frequency rate decreased significantly with checklist implementation (p < 0.05).

CONCLUSION

A quick checklist for quality control of UDS was developed. The quick checklist as a convenient, quick, and easy used urodynamic quality control method, may help to reduce the technical artefacts and improve fundamental urodynamic quality control. Future research with a larger sample size is needed to confirm the effectiveness of the checklist.

An automatic diagnostic system for the urodynamic study applying in lower urinary tract dysfunction

OBJECTIVE

To establish an automatic diagnostic system based on machine learning for preliminarily analysis of urodynamic study applying in lower urinary tract dysfunction (LUTD).

METHODS

The eight most common conditions of LUTDs were included in the present study. A total of 527 eligible patients with complete data, from the year of 2015 to 2020, were enrolled in this study. In total, two global parameters (patients' age and sex) and 13 urodynamic parameters were considered to be the input for machine learning algorithms. Three machine learning approaches were applied and evaluated in this study, including Decision Tree (DT), Logistic Regression (LR), and Support Vector Machine (SVM).

RESULTS

By applying machine learning algorithms into the 8 common LUTDs, the DT models achieved the AUC of 0.63-0.98, the LR models achieved the AUC of 0.73-0.99, and the SVM models achieved the AUC of 0.64-1.00. For mutually exclusive diagnoses of underactive detrusor and acontractile detrusor, we developed a classification model that classifies the patients into either of these two diseases or double-negative class. For this classification method, the DT models achieved the AUC of 0.82-0.85 and the SVM models achieved the AUC of 0.86-0.90. Among all these models, the LR and the SVM models showed better performance. The best model of these diagnostic tasks achieved an average AUC of 0.90 (0.90 ± 0.08).

CONCLUSIONS

An automatic diagnostic system was developed using three machine learning models in urodynamic studies. This automated machine learning process could lead to promising assistance and enhancements of diagnosis and provide more useful reference for LUTD treatment.

ICS-SUFU standard: Theory, terms, and recommendations for pressure-flow studies performance, analysis, and reporting. Part 1: Background theory and practice

AIMS

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

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 January 2023 to facilitate public discussion and the comments received have been incorporated into this final release.

RESULTS

The WG summarizes the theory and recommends the practice and the terms used for the diagnosis of voiding dysfunction for adult female and male patients without relevant neurological abnormalities, in part 1 of this standard. The WG has also recommended standard principles and parameters for objective and continuous grading of urethral resistance and detrusor voiding contraction on the basis of pressure flow studies in part 2. The recommendations for practice in this part have also the aim to increase the understanding of the physiology as well as the psychology of voiding. The potential effects of the laboratory situation of the test on the voiding as well as the role of the urodynamicist in this regard are discussed. The WG has recommended to use for diagnosis only the voidings that are considered representative by the patient.

CONCLUSION

A pressure flow study is the gold standard to assess voiding function and to quantify dysfunction. This part of the standard explains the clinical background, gives recommendations for the execution of a pressure flow study and lists relevant terms, parameters, and units of measurements.

Straining to void at preoperative urodynamic study as a risk factor for prolapse recurrence after surgery

OBJECTIVES

Straining to void is the need to make a muscular effort in order to initiate, maintain or improve the urinary stream, through an increase in abdominal pressure. This pattern of bladder emptying is frequently observed in women with pelvic organ prolapse causing urinary obstruction, to overcome the increased resistance to urine flow. However, frequent increases in abdominal pressure are a risk factor for developing pelvic organ prolapse, and might play a role in its recurrence after surgery. The aim of this study was to investigate the role of straining identified at urodynamic study in prolapse recurrence after surgical repair.

STUDY DESIGN

This was a retrospective study on women submitted to prolapse repair by vaginal hysterectomy with modified McCall culdoplasty and anterior colporraphy. All patients underwent a preoperative urodynamic evaluation including a pressure-flow study performed after prolapse reduction by means of a vaginal pessary; straining was defined by a simultaneous and similar increase in intravesical and abdominal pressures of at least 10 cmH₂O over the baseline during bladder emptying, corresponding to intermittent peaks of urine flow. Patients were divided into two groups according to the presence or absence of straining, and they were compared for surgical results at 12 months and for the rate of anterior or central recurrence over time.

RESULTS

Women with straining (n = 16), compared to women with normal voiding (n = 43), showed a higher risk of anterior recurrence over time at Kaplan-Meier curves, for both stage II (p = 0.02) and stage III prolapse (p = 0.02). No difference was seen for central recurrence during the follow up period. POP-Q staging at 12 months was similar for the two groups, except for the location of the Aa point which was significantly better for women without straining (-1.6 ± 0.1 cm vs -0.8 ± 0.3 cm, p = 0.03).

CONCLUSIONS

Straining to void identified in preoperative urodynamic study seems to increase the risk of anterior recurrence after surgical repair of pelvic organ prolapse.

Choice of cystometric technique impacts detrusor contractile dynamics in wistar rats

The objective of the current animal study was to investigate factors contributing to the different phases of the cystometrogram (CMG) in order to address disparities in research data reported in the current literature. Three experiments in 20 female Wistar rats were designed to investigate (1) the effects of anesthesia on the contractile pattern of the bladder during micturition; (2) the impact of the physical characteristics of the CMG technique upon the accuracy of intra-vesical pressure recordings; and (3) identification of physiological and methodological factors associated with the emptying and rebound phases during CMG. Variables tested included awake versus urethane-anesthetized conditions, use of a single catheter for both filling and intra-vesical pressure (Pves) recording versus a separate two catheter approach, and comparisons between ureter, bladder dome, and urethral catheter placements. Both awake and anesthetized conditions contributed to variations in the shape and magnitude of the CMG pressure curves. In addition, catheter size, acute incision of the bladder dome for catheter placement, use of the same catheter for filling and Pves recordings, as well as the placement and positioning of the tubing, all contributed to alterations of the physiological properties and characteristic of the various CMG phases, including the frequent occurrence of an artificial rebound during the third phase of micturition. The present results demonstrate how different experimental conditions lead not only to variability in Pves curves, but consistency of the measurements as well, which needs to be accounted for when interpreting CMG outcome data.

Pitfalls in Urodynamics

Although urodynamics (UDS) is essential for the diagnosis and treatment of neurogenic lower urinary tract dysfunction, several possible pitfalls can be identified. In this paper we identify pitfalls in UDS and highlight limiting factors. UDS pitfalls that depend on the patient, on the physician, or on the test itself are described and analyzed. PATIENT SUMMARY: In this report we looked into pitfalls of urodynamics. Urodynamics is an essential tool in the diagnosis and treatment of neurogenic lower urinary tract dysfunction and always requires standardization and quality control to limit possible pitfalls.

Quality control of uroflowmetry and urodynamic data from two large multicenter studies of male lower urinary tract symptoms

AIM

The International Continence Society (ICS) has standardized quality control and interpretation of uroflowmetry and urodynamics. We evaluated traces from two large studies of male lower urinary tract symptoms (UPSTREAM and UNBLOCS) against ICS standards of urodynamic equipment and practice.

METHODS

Ten percent of uroflowmetry and urodynamics traces were selected at random from hospital sites. A data capture template was designed from the ICS Fundamentals of Urodynamic Practice checklist. Two pretrained blinded assessors extracted the data, with a third assessor to arbitrate. Departmental records of calibration checks and equipment maintenance were scrutinized.

RESULTS

Seven out of twenty-five (28%) departments reported no calibration checks. Four sites (16%) could not provide annual service records. In 32 out of 296 (10.8%) uroflowmetry traces, findings were affected by artifact. One hundred ten urodynamic study traces were reviewed; in 11 records (10%), key pressure traces were incompletely displayed. In 30 (27.2%), reference zero was not set to atmospheric pressure. Resting pressures were outside the expected range for 36 (32.7%). Pressure drift was seen in 18 traces (16.4%). At pressure-flow study commencement, permission to void was omitted in 15 (13.6%). Cough testing after voiding was done in 71.2%, but the resulting cough spikes were significantly different in 16.5%. Erroneous diagnosis of bladder outlet obstruction (BOO) was identified in six cases (5.5%).

CONCLUSIONS

Erroneous diagnosis of BOO is a serious error of interpretation, as it could lead to unnecessary surgery. Other errors of standardization, testing, and interpretation were identified with lower risk of adverse implications. Inconsistent documentation of service records mean equipment accuracy is uncertain.

Can rectal catheters be avoided during paediatric urodynamic studies?

Objective: To determine if the interpretation of urodynamic studies (UDS) in children without a rectal catheter may be similar to multi-channel studies, as UDS in children are challenging and can sometimes be difficult to interpret.

Patients and methods: In this retrospective pilot study, 115 paediatric pressure–flow studies were included. A blinded investigator was given two sets of UDS traces. The first set had the vesical trace of all children and the second set had the multi-channel trace. The agreement between the interpretations of both the sets was tested by Cohen’s κ, and sensitivity, specificity, and predictive values were expressed with 95% confidence intervals (CIs). The voiding pattern was compared and Pearson’s correlation coefficient was used to analyse the pressure at maximum urinary flow (Q_max).

Results: The most common indications for UDS were neurogenic bladder and posterior urethral valves. The interpretation of compliance and detrusor overactivity by single-channel analysis had a positive predictive value of 92.1% (95% CI 84.7–96.1%) and 89.4% (95% CI 78.3–95.6%), respectively, and a negative predictive value of 100% and 97.1% (95% CI 89.5–99.2%) respectively, in comparison to multi-channel analysis. Children with underactive detrusor were identified reliably by analysing the straining pressure pattern and flow curve. Amongst children who voided, the pressure at Q_max showed a moderate correlation (Pearson’s coefficient = 0.53) between the two groups.

Conclusion: Rectal catheters may be avoided in a carefully selected group of children undergoing UDS who only need filling phase assessment.

Abbreviations: DO: detrusor overactivity; EBC: expected bladder capacity; P_abd: abdominal pressure; P_det: detrusor pressure; PUV: posterior urethral valve; (N)(P)PV: (negative) (positive) predictive value; P_ves: vesical pressure; Q_max: maximum urinary flow rate; UDS: urodynamic studies; UI: urinary incontinence

Is the value of urodynamics undermined by poor technique?: ICI-RS 2018

INTRODUCTION

The quality of urodynamic measurements in clinical practice has been debated as a matter of concern. It is considered plausible that this has a direct bearing on patient care and the perceived value of urodynamic testing.

METHODS

This is a report of the proceedings of the Think Tank: "Is the value of urodynamics undermined by poor technique?" from the Annual International Consultation on Incontinence-Research Society, which took place in June 2018 in Bristol, UK. The Think Tank discussed the evidence for deficiencies in urodynamic test quality and considered the implications of improvements for clinical diagnosis and practice.

RESULTS

There is evidence that technique affects urodynamic quality, and that urodynamic practice is variable. Factors such as team skill set, technologies used, and training received will also affect the quality of urodynamic service. Questions exist regarding the influence of technique on the utility and perceived value of urodynamics.

CONCLUSIONS

We suggest research questions that will provide the necessary evidence on the link between technique, reporting, and outcome, and clarify the role of good practice in the utility of urodynamic testing.

Wireless intravesical device for real-time bladder pressure measurement: Study of consecutive voiding in awake minipigs

Traditional urodynamics have poor correlation with urological symptoms. Ambulatory urodynamics may improve this correlation but the need for a transurethral catheter and the time-consuming nature of this examination limits its use. Therefore, the objective of this study was to develop a wireless real-time bladder pressure measurement device for repeated and prolonged-term measurement of bladder behavior in awake pigs. The Bladder Pill is an intravesical device with a pressure microsensor and a 3-dimensional inductive coupling coil for energy supply. A corresponding external coil provides wireless power transmission and real-time communication of bladder pressure data. To test the correlation between the pressure data measured by the device and by standard methods, we compared static water column pressures with this device and water-filled urodynamic catheter systems. In vivo assessment of awake voiding by the pill was done by introducing the bladder pill into the bladder of Göttingen minipigs. An air-charged urodynamic catheter was introduced transurethrally as control for pressure measurements. The optimal physical configuration of the pill was investigated to maximize the containment in the bladder. We used two versions of external signal receivers (one waistband and one rectangular frame) to test the optimal external signal capture. Next to that, we performed short-term and medium-term comparative pressure studies. The in vitro static pressure measurement demonstrated a mean difference of less than 1 cm H₂O between the methods. The optimal design of the pill for maximal retainment in the bladder proved to be a pigtail configuration. The bending of the device during bladder contractions caused offset of 2.7 +/- 1.4 cm H₂O (mean +/- SD) on the pressure measurements. The rectangular frame performed signal capture during 5 consecutive voids with a good correlation of the pressure measurements. The device can be inserted through the urethra and is retrieved using string or endoscopic extraction. In conclusion, wireless long-term measurement of bladder pressure is demonstrated and yields comparable results to current available catheter methods of measurement in a pig model.

Is Urodynamics Necessary when Assessing a Patient with Male Lower Urinary Tract Symptoms?

Urodynamics can distinguish bladder outlet obstruction from detrusor underactivity. Clear identification of the mechanism of a man's voiding symptoms can help give the best chance of good outcome from surgery. Publication of results from the UPSTREAM study will help in establishing the exact place for urodynamic testing in male lower urinary tract symptoms.

Work Capacity of the Bladder During Voiding: A Novel Method to Evaluate Bladder Contractile Function and Bladder Outlet Obstruction

Background:

Work in voiding (WIV) of the bladder may be used to evaluate bladder status throughout urination rather than at a single time point. Few studies, however, have assessed WIV owing to the complexity of its calculations. We have developed a method of calculating work capacity of the bladder while voiding and analyzed the associations of bladder work parameters with bladder contractile function and bladder outlet obstruction (BOO).

Methods:

The study retrospectively evaluated 160 men and 23 women, aged >40 years and with a detrusor pressure at maximal flow rate (P_det Q_max) of ≥40 cmH₂O in men, who underwent urodynamic testing. The bladder power integration method was used to calculate WIV; WIV per second (WIV/t) and WIV per liter of urine voided (WIV/v) were also calculated. In men, the relationships between these work capacity parameters and P_det Q_max and Abrams-Griffiths (AG) number were determined using linear-by-linear association tests, and relationships between work capacity parameters and BOO grade were investigated using Spearman's association test.

Results:

The mean WIV was 1.15 ± 0.78 J and 1.30 ± 0.88 J, mean WIV/t was 22.95 ± 14.45 mW and 23.78 ± 17.02 mW, and mean WIV/v was 5.59 ± 2.32 J/L and 2.83 ± 1.87 J/L in men and women, respectively. In men, WIV/v showed significant positive associations with P_det Q_max (r = 0.845, P = 0.000), AG number (r = 0.814, P = 0.000), and Schafer class (r = 0.726, P = 0.000). Conversely, WIV and WIV/t showed no associations with P_det Q_max or AG number. In patients with BOO (Schafer class > II), WIV/v correlated positively with increasing BOO grade.

Conclusions:

WIV can be calculated from simple urodynamic parameters using the bladder power integration method. WIV/v may be a marker of BOO grade, and the bladder contractile function can be evaluated by WIV and WIV/t.

Recommendations for future development of contractility and obstruction nomograms for women. ICI-RS 2014

AIMS

At present, existing bladder outlet obstruction (BOO) nomograms for women are still not universally accepted. Moreover, only limited information is available regarding bladder contractility in women. The aim is to present the discussions and recommendations from the think tank session "Can we construct and validate contractility and obstruction nomograms for women?" held at the 2014 International Consultation on Incontinence-Research Society (ICI-RS) meeting in Bristol, UK.

METHODS

An overview of clinical significance, bladder mechanics and modelling, lack of existing nomograms for women, and development of new nomograms were presented and discussed in a multidisciplinary think tank session. This think tank session was based on a collaboration between physicians, engineers, and researchers and consensus was achieved on future research initiatives.

RESULTS AND CONCLUSIONS

Based on the think tank discussion, the ICI-RS panel put forward the following recommendations: the need to acquire normative age-matched data in women to define "normal" and "pathological" values of urodynamic parameters; the inclusion of additional clinical data in new nomograms and the use of this extra dimension to develop clinically applicable nomograms for female BOO and contractility; and finally, the need to take into account the variability of BOO in women when developing female bladder contractility nomograms.

Routine enema before urodynamics has no impact on the quality of abdominal pressure curves: Results of a prospective controlled study

AIMS

The presence of stools in the rectum might affect the quality of the abdominal pressure curve during filling cystometry, but, to date, no study has evaluated the impact of bowel preparation before urodynamics. We evaluated the influence of a sodium phosphate enema before urodynamics on the quality of the abdominal pressure curve.

METHODS

A prospective, controlled, single-blind study was conducted in a single center from May to June 2013. The patients were divided into 2 consecutive groups: patients seen in outpatient clinics during the first 6 weeks (group A) who underwent urodynamics without bowel preparation and patients seen in outpatient clinics during the second 6 weeks (group B) who had a prescription of sodium phosphate enema before urodynamics. The primary endpoint was the quality of the abdominal pressure curve evaluated independently by three physicians who were blinded to the study group. The following data were also collected: age, gender, the presence of a neurological disorder, complicated nature of urodynamics and bother related to preparation for it, assessed using a Likert scale (0 to 10), and the equipment used. A per protocol analysis and an intent-to-treat analysis were conducted.

RESULTS

One hundred and thirty-nine patients were included: 54 in group A and 85 in group B. One-third of patients had neurological conditions. 14 patients in group B did not perform their scheduled enema. Thus, 68 patients performed an enema before urodynamics and 71 did not. There was no difference between groups A and B regarding the complicated nature of urodynamics (Likert scale: 3.12 vs. 3.18; P=0.91) or bother related to preparation for it (Likert scale: 3.46 vs. 2.97; P=0.43). In the per protocol analysis, the abdominal pressure curve was considered perfectly interpretable (PI) in 69% of patients who did not receive an enema before urodynamics and in 65% of patients who did (P=0.61). The between-group difference was not statistically significant in intent-to-treat analysis (P=0.99). In patients who did not receive an enema before urodynamics, the only factors statistically associated with better quality of abdominal pressure curves were age <60years (P=0.001) and the urodynamic equipment used (Dantec^®>Laborie^®; P=0.01).

CONCLUSION

In this prospective study, routine enema before urodynamics did not improve the quality of the abdominal pressure curve and did not increase the complicated nature of urodynamics or the bother of preparation for it.

LEVEL OF EVIDENCE

3.

Typical Value Ranges and Typical Signal Patterns in the Initial Cough in Patients With Neurogenic Bladder: Quality Control in Urodynamic Studies

Purpose

The goal of this study was to establish typical value ranges (TVRs) and to analyze typical signal patterns (TSPs) of the initial cough (cough before bladder filling) for quality control in urodynamic studies.

Methods

A total of 539 urodynamic traces from patients with neurogenic bladder obtained over the course of a year were retrospectively reviewed. The TVRs for cough amplitude in measurements of the intravesical pressure (P_ves), abdominal pressure (P_abd), and detrusor pressure (P_det) during the initial cough were established. We used the 95% range as a reference range for all parameters. Cough spikes in P_det were described and classified, and the reasons for different patterns of cough spikes were established. The quality of all the cystometry traces was checked, and we also present remedial actions for inappropriate cough spikes.

Results

The cough amplitudes in the measurements of P_ves and P_abd were similar, with 95% of measurements falling within the following ranges: 4–62 cm H₂O and 3–70 cm H₂O, respectively, in supine position and 9–95 cm H₂O and 8–98 cm H₂O, respectively, in sitting position. For P_det, the cough amplitude ranged from −38 to 25 cm H₂O in supine position and from −44 to 41 cm H₂O in sitting position. The cough spikes for P_det were classified as follows: type I, P_det pressure exhibited a minimal change (<5 cm H₂O) during the cough; type II, a monophasic spike (>5 cm H₂O) was observed for P_det; and type III, biphasic spikes were observed for P_det. Type I coughs were found to have more high-quality traces (P<0.01).

Conclusions

TVRs for the initial cough test among neurogenic patients were established in order to provide guidelines for quantitative quality control. The TSPs for the initial cough signal were described, and the presence of a high-quality cough signal may be recommended as a component of quality control in urodynamic measurements.

ICS teaching module: Artefacts in urodynamic pressure traces (basic module)

AIMS

To present the ICS Teaching Module on artefacts in urodynamics pressure traces.

METHODS

Slides from three urodynamics centres were assembled. Descriptions and labels were agreed by the authors and the module presented at the ICS Annual Scientific Meeting in Brazil 2014.

RESULTS

Ten artefacts that should be recognized while using water-filled urodynamic systems are presented and remedial action described.

CONCLUSIONS

This manuscript serves as scientific background for the slide set made available on the ICS website. By following the guidelines in this teaching module, good quality urodynamics can be more readily achieved. Neurourol. Urodynam. 36:35-36, 2017. © 2015 Wiley Periodicals, Inc.

Detrusor after-contraction: a new insight

Aims:

Detrusor after-contractions (DAC) are non-common in adults. Both definition (nothing in ICS reports) and significance (artefact, link with detrusor overactivity (DO) or bladder outlet obstruction (BOO)) remain discussed. Our purpose was to carry out an analysis of the urodynamic parameters during voidings with DAC and, using the VBN model, to simulate pathophysiological conditions able to explain both voiding phase and DAC.

Materials and Methods:

From large urodynamic database of patients referred for evaluation of lower urinary tract dysfunction, DAC were observed in 60 patients (5.7%). Criteria for DAC were post-void residual <30mL and increase of detrusor pressure >10cmH₂O. VBN model was used for analysis of both pressure and flow curves, and simulations of pathophysiological conditions.

Results:

Onset of DAC (ODAC) occurred when Q=7.3±5.7mL/s and bladder volume=17.9±15.4mL. Urgency-frequency syndrome and urodynamic diagnosis of DO were the more frequent scenarios associated with DAC. ODAC was associated to an inversion of the slope of detrusor pressure curve without any perturbation in flow curve. Among tested pathophysiological hypothesis (great, abnormal, detrusor force, sphincter contraction), none allowed restoring all recorded curves (flow rate, voiding pressure and DAC).

Conclusion:

No urodynamic characteristic of the first part of voiding is an index of occurrence of DAC. ODAC is a significant phenomenon linked with the bladder collapse. DAC is not associated with BOO but more probably with DO and appears as the result of local conditions in an almost empty bladder (concentration of stresses around a transducer); thus DAC seems of weak clinical significance.

Urodynamics in stress incontinence: when are they necessary and how do we use them?

Stress urinary incontinence is a prevalent condition that significantly impairs the quality of life. This article presents a critical summary of the current literature on the use and value of urodynamic studies in the evaluation of stress urinary incontinence in women.

Quantitative quality control during urodynamic studies with TVRs for cystometry in men with lower urinary tract symptoms suggestive of benign prostatic hyperplasia

OBJECTIVE

To establish typical value ranges (TVRs) and to outline their role in urodynamic quality control.

METHODS

Five hundred and eighty-two data sets of free flow, filling cystometry, and voiding from 181 males in a strictly quality-controlled study were analyzed for intravesical pressure (Pves), abdominal pressure (Pabd), and detrusor pressure (Pdet) before, at the beginning and end of filling, and after voiding. Cystometric capacity, maximum flow rate (Qmax), voided volume (Vvoid), and compliance were determined. Mean value, standard deviation, median, and various TVRs were calculated. Technical errors related to the TVRs are classified and examples given.

RESULTS

TVRs for initial resting Pves, Pabd, and Pdet were 31-42, 28-39, and 0-4 cmH₂O, respectively. Various technical errors are classified as type I: normal initial Pdet, both Pves and Pabd are incorrect; type II: negative initial Pdet; and type III: initial Pdet too high. The incidences of I, II, and III errors were 9.8, 4.5, and 1.4%, respectively. The TVRs for maximum cystometric capacity and compliance were 157-345 mL and 26.7-70.8 mL/cmH₂O; Qmax, Pdet, and Vvoid were 5.5-9 mL/s, 57-92 cmH₂O, and 167-315 mL, respectively; Qmax and Vvoid in free flow were 8-9.2 mL/s and 167-301 mL, respectively. After voiding, two errors were found: type V (Pves and Pdet after voiding still high) and type VI (Pves and Pdet negative).

CONCLUSIONS

TVRs in urodynamics are indispensable and effective tools for quantitative plausibility checks and quality control. They are sensitive and reliable indicators for correct measurement and a relevant contribution to a collection of normal values.

Qualitative quality control during urodynamic studies with TSPs for cystometry in men with lower urinary tract symptoms suggestive of benign prostatic hyperplasia

The aim of this study was to describe typical signal patterns (TSPs) by amplitude and pressure gradients and indicate the role and significance of them in quality control. A total of 582 measurements from a multicenter urodynamic study on males (mean age, 65.3 years) were re-analyzed. Using manual graphical analysis, we identified signal patterns by typical amplitude (A) and typical pressure gradient (PG). TSPs were classified into four types: I: fine structure (A < 3 cm H2O); II: minor dynamic changes (A < 5 cm H2O); III: major changes due to cough tests (A > 50 cm H2O, PG > 100 cm H2O/s); IV: typical major changes due to muscular activity: detrusor overactivity (A > 3 cm H2O, PG > 1-5 cm H2O/s), rectal contractions (A = 5-10 cm H2O, PG = 5-10 cm H2O/s), and straining (A > 5 cm H2O, PG ≥ 30 cm H2O/s). At beginning of and during filling, 91.8 and 98.3 % of traces showed the identical fine structure and minor changes between P ves and P abd tracings, and P det tracing was quiet. 92.3 % of P ves and P abd traces had equal pressure changes at test coughs. During filling, 8.3 % traces showed straining, 17.4 % showed rectal contractions, and 33.7 % showed detrusor overactivity. Before voiding, 94 % of P ves and P abd traces had equal cough response. During voiding, 91.2 % of traces showed the same fine structure, 53.3 % of traces showed straining, and 15.3 % showed relaxation of the pelvic floor. After voiding, 91.2 % of traces had the same fine structure, and 87.5 % had an equal cough response. TSPs are a powerful tool for qualitative plausibility and quality control and are an indispensable pre-condition for good urodynamic practice.

Clinically relevant modeling of urodynamics function: the VBN model

BACKGROUND

For the past two decades, a mathematical model of micturition was built step by step. Fundamental studies, presentations of the model and several applications to various male and female lower urinary tract dysfunctions have been published. We expect now that other teams will be interested in using it. In order to do so, a VBN pack (software in Linux and tutorial) is freely available.

AIMS

The purpose of this review is to describe the model and to show its practical usefulness.

MATERIALS AND METHODS

After a short description of the basis of the model and of how to use it, some published applications were summed up. The main application of the VBN model is to obtain a coherent modelling for a given patient from a set of several recordings (free uroflows and pressure-flow study) obtained either during the same session or in follow up.

RESULTS

This experience gradually led us to study what information could be extracted from a free uroflow. In addition, the model is valuable to quickly compute the effect of some additional condition; thus, it can predict the effect of an experimental artefact (urethral catheter, penile cuff).

CONCLUSION

Because the process of fitting model computations and real recordings is a powerful way to detect unexpected phenomena, the use of the VBN model provides a method to improve the knowledge of misunderstood dysfunctions of the lower urinary tract.