Isovolumetric Bladder Pressure Research Articles

Characterization and in vivo efficacy of a heptapeptide ODT formulation for the treatment of neurogenic bladder dysfunction

The objective of this study was to develop oral disintegrating tablet (ODT) formulations of a heptapeptide, [Lys5,MeLeu9,Nle10]-NKA(4–10), for the treatment of neurogenic bladder dysfunction. A design of experiment approach was applied to determine the optimal ratio of chosen excipients: gelatin (X1), glycine (X2), and sorbitol (X3). These formulations were optimized for efficacy studies to produce ODTs exhibiting rapid disintegration times (Y1) and appropriate structural integrity (Y2) using JMP® 12.0.1 software. Based on theoretically predicted values from 12 experimental runs, the optimal ODT formulation was determined to be 3% (w/v) gelatin, 2% (w/v) glycine, and 1% (w/v) sorbitol in deionized water. Using this formulation, blank and drug-loaded ODTs containing 1.5 mg or 5 mg of [Lys5,MeLeu9,Nle10]-NKA(4–10) were manufactured by a lyophilization process. The peptide-loaded tablets disintegrated in less than 30 s and released 97% of the peptide within 15 min. The peptide was stable for 90 days under 25 °C/60% relative humidity (RH) and 40 °C/75% RH. In vivo efficacy of the peptide-loaded ODTs was confirmed in a rat acute spinal cord injury model under isovolumetric bladder pressure recording conditions, concluding that sublingual administration of peptide-containing ODTs evoke a rapid dose-related neurokinin 2-mediated increase in bladder pressure.

Diagnosing bladder outlet obstruction using the penile cuff test in men with lower urinary tract symptoms.

The current standard diagnostic test to evaluate bladder outlet obstruction (BOO) is pressure-flow study (PFS). The penile cuff test (PCT) was introduced as a non-invasive alternative to PFS to determine the isovolumetric bladder pressure and also flow rate. The aim of the study was to evaluate the diagnostic accuracy and acceptability of the PCT, compared to those of PFS, in the assessment of BOO in men. A total of 146 consecutive men with an International Prostate Symptom Score (IPSS) >12 and lower urinary tract symptoms (LUTS) for >6 months were included in this single-institution, prospective, diagnostic study. The primary outcome was to evaluate the diagnostic accuracy of PCT. Secondary outcomes included pain severity measured on a visual analog scale (VAS), procedure time, and adverse events. In addition, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were estimated. Based on the PFS results, the sensitivity of PCT was 89.7%, the PPV 54.2%, the specificity 71.8%, and the NPV 94.9%. The mean pain VAS for the PFS and PCT were 5.04 ± 2.17 and 1.83 ± 1.98, respectively (P < 0.0001). The mean procedure time for PCT (6.3 ± 0.6 min) was shorter than that of PFS (23.3 ± 2.2 min) (P < 0.0001). There were no adverse events reported during PCT. Given its high NPV, PCT may be an efficient screening test for BOO in men. In addition, PCT is advantageous over PFS with regard to its short procedure time and acceptable tolerability.

Urinary Bladder Contractility Revisited. Correlation of Noninvasively and Invasively Measured Contractility Parameters in Patients Eligible for Transurethral Resection of the Prostate

To validate a noninvasively estimated measure of urinary bladder contractility by correlating it with 3 existing invasive contractility parameters and to compare and correlate those invasive parameters. A group of 74 patients, recruited in 3 different hospitals, and eligible for transurethral resection of the prostate on clinical grounds, were noninvasively studied preoperatively using the condom catheter method. The maximum condom pressure pcond.max measured during a mechanical interruption of flow rate was considered an estimate of urinary bladder contractility and compared to conventional contractility parameters calculated from preoperative (invasive) pressure-flow studies. The highest correlations were found between the invasive parameters. The correlation between the noninvasive parameter on the one hand and the invasive parameters on the other hand was lower, but mostly significant. In a number of patients, pcond.max underestimated the isovolumetric bladder pressure. The underestimated patients were more obstructed than those who were not underestimated and had a higher (invasively measured) contractility. When the underestimated patients were deselected, the correlation between the noninvasive pcond.max and the invasive parameters in the remaining 52 patients was higher. The 4 tested contractility parameters represent different aspects of urinary bladder contractility. Nevertheless, there was a significant correlation among them supporting the concept of a common basis, that is, detrusor contractility. The invasive contractility parameter bladder contractility index overestimated contractility in patients with lower urinary tract symptoms and/or benign prostatic enlargement. A modified parameter is suggested.

Diagnostic power of the noninvasive condom catheter method in patients eligible for transurethral resection of the prostate

The aim of this study was to determine the accuracy of the non-invasive condom catheter method for diagnosing B(ladder) O(utlet) O(bstruction) in patients eligible for T(rans)U(rethral) R(esection) of the P(rostate). A group of 71 patients eligible for TURP on clinical grounds were invasively and non-invasively studied. On the basis of invasive pressure-flow studies they were stratified into obstructed, equivocal or unobstructed, according to the International Continence Society standard. Subsequently they were diagnosed non-invasively on the basis of a free flowrate measurement, or on the basis of the free flowrate measurement plus the isovolumetric bladder pressure measured with the condom catheter method. R(eceiver) O(perating) C(haracteristic)s were calculated. The A(rea) U(nder) the (RO)C for discriminating unobstructed/equivocal patients from obstructed patients was 0.68 in our population. This improved to 0.84 for the 50 patients in whom the isovolumetric bladder pressure was not underestimated by the non-invasive method. In our population of TURP patients, the low flowrates affected the accuracy of the condom method to a degree that it did not perform better than a free flowrate measurement, which performed remarkably well. By excluding measurements in which the condom pressure underestimated the isovolumetric bladder pressure this method may contribute to a more accurate, patient friendly diagnosis of BOO in these patients. In the present study this exclusion was done by comparison with an invasive pressure measurement. A practical non-invasive test would necessitate a non-invasive exclusion criterion, which might be based on the risetime of the condom pressure.

Longitudinal changes in isovolumetric bladder pressure in response to age‐related prostate growth in 1,020 Healthy male volunteers

To non-invasively study if compensation and decompensation occurs in the urinary bladder of healthy male volunteers in response to benign prostatic enlargement (BPE) using the condom catheter method. Between 2001 and 2010, 1,020 healthy male volunteers were included in a longitudinal study based on three non-invasive urodynamic examinations during a 5-year follow-up. Inclusion criteria were an informed consent, the ability to void in a normal standing position and a minimum free flow rate of 5.4 ml/sec. Study parameters were prostate volume (PV), maximum free urinary flow rate (Q(max)) and bladder contractility, quantified by the maximum isovolumetric bladder pressure, measured in the condom (P(cond.max)). Volunteers also completed the International Prostate Symptom Score Form (IPSS). Within limitations, the included volunteers had a flat age distribution between 38 and 72 years. This made it possible to combine longitudinal analysis in a 5-year observation interval, with cross sectional analysis in a 35-year age range. Longitudinal analysis showed that with increasing age, PV increased with 1.9% per year, whereas Qmax decreased with 1.1% per year. IPSS increased with 1.1% per year when volunteers were older than 55 years. P(cond.max) increased during the 5-year longitudinal follow-up, but not in the cross sectional analysis. The difference between cross sectional and longitudinal results of the P(cond.max) may have been caused by compensation of the urinary bladder resulting in a selection effect. This would imply that compensation is a relatively fast process, taking approximately 5 years.

Valeur prédictive du cuff-test dans le diagnostic de l’obstruction sous-vésicale chez l’homme

To assess the diagnostic performances and the acceptability of the penile cuff test (PCT) which is a non invasive method for the evaluation of bladder outlet obstruction (BOO), in comparison with the pressure flow study (PFS), the actual gold-standard. Monocentric prospective study comparing the following subsets: "obstructed", "not obstructed" or "equivocal", deduced from PFS vs PCT, in 30 consecutive patients presenting with lower urinary tract symptoms. For the PCT, a cuff placed around the penis inflated automatically during the micturition, until flow rate interruption. The interruption cuff pressure revealed the isovolumetric bladder pressure (Pcuff-int). The data collected - Pcuff-int and maximum flow rate - were automatically reported on ICS modified nomogram. With the PFS, 11 patients (39%) were classified "obstructed", six patients (22%) "non-obstructed" and 11 patients (39%) "equivocal". In 61% cases, the patient was classified in the same category by both techniques. The "obstructed positive predictive value" of the PCT was 82% and the "non-obstructed-equivocal negative predictive value" was 88%. The median acceptability visual analogic scale score was 1/10 (0-3) for the PCT whereas it was 5/10 (2-10) for the PFS. This difference was statistically significant (p=0.004). The PCT was a reliable non-invasive tool for the diagnosis of BOO in male, in comparison with PFS. The predictive values of the PCT were relevant and its tolerance was better than PFS.

Multiple Pudendal Sensory Pathways Reflexly Modulate Bladder and Urethral Activity in Patients With Spinal Cord Injury

Electrical stimulation of pudendal afferents can evoke reflex bladder contractions with relaxation of the external urethral sphincter in cats. This voiding reflex is mediated by pudendal sensory fibers innervating the penile and prostatic urethra that engage spinal and spinobulbospinal micturition pathways, respectively. However, clinical translation of this potential therapy in individuals with spinal cord injury is limited by the lack of evidence showing analogous reflex mechanisms in humans. We investigated excitatory pudendal-to-bladder reflexes in 7 individuals with chronic spinal cord injury. We recorded isovolumetric bladder pressure and perineal electromyogram in response to intraurethral electrical stimulation at varying amplitudes and frequencies. Selective electrical stimulation of the proximal (29.7 ± 11.6 cm H(2)O) and distal urethral (23.3 ± 9.28 cm H(2)O) segments evoked sustained reflex bladder contractions in different subsets (3 each) of participants. In contrast, the corresponding reflex perineal electromyogram revealed a differential activation pattern between proximal and distal intraurethral stimulation (normalized electromyogram of 1.3 ± 0.2 and 0.3 ± 0.1, respectively, p <0.05). To our knowledge we report the first clinical evidence of 2 independent excitatory pudendal-to-bladder reflex pathways, which in turn differentially modulate efferent pudendal output. Each reflex mechanism involves complex interaction of multiple sensory inputs and may provide a neural substrate to restore micturition after spinal cord injury.

The role of invasive and non-invasive urodynamics in male voiding lower urinary tract symptoms

Troublesome voiding lower urinary tract symptoms (LUTS) are a common problem in men, particularly with ageing. Implicitly, management of voiding LUTS can be guided by accurate determination of underlying mechanisms, distinguishing men with voiding symptoms caused by outlet obstruction from those with reduced bladder contractility. A PubMed search of the published literature on invasive and non-invasive methods used to assess lower urinary tract function was carried out. A multitude of methods have been applied to assess LUTS. Multichannel pressure flow studies (PFS) are the standard for diagnosing bladder outlet obstruction and underlying mechanisms of LUTS, though their invasive nature can be difficult to tolerate, and improved prediction of treatment outcome is disputed. Uroflowmetry and post void residual measurement are insufficient to make a definitive diagnosis. Ultrasound-derived measurements of bladder wall thickness and estimated bladder weight offer a potential non-invasive alternative to PFS, but their diagnostic parameters are still under evaluation. Non-invasive methods that measure isovolumetric bladder pressure by interrupting the urinary stream can reproducibly measure pressure and urinary flow, but are unable to determine the effects of abdominal straining during voiding and give no insight into urine storage symptoms. Doppler ultrasound during urethral flow is informative, but it is an expensive approach whose clinical utility has yet to be established. A variety of non-invasive urodynamic and non-urodynamic techniques have been used to evaluate LUTS and some show great promise. However, there is as yet, insufficient evidence to justify replacement of invasive voiding cystometry by these investigational approaches.

Positioning invasive versus noninvasive urodynamics in the assessment of bladder outlet obstruction

To provide evidence of promising tests to noninvasively diagnose bladder outlet obstruction (BOO) in men with benign prostatic hyperplasia. Pressure-flow studies are usually performed to prove BOO prior to prostatectomy. However, pressure-flow studies are invasive, expensive, time consuming, and potentially harmful to the patient due to unwarranted side-effects. In the last decade, attempts were made to diagnose BOO noninvasively. Ultrasound-derived measurements such as bladder or detrusor wall thickness or intravesical prostatic protrusion and urodynamic-derived measurements such as isovolumetric bladder pressure by the condom catheter or penile cuff tests show promising results. Likelihood ratios of all tests were calculated for this study and indicated a good ability to detect BOO. Noninvasive measurements of bladder/detrusor wall thickness, intravesical prostatic protrusion, or isovolumetric bladder pressure might replace invasive pressure-flow studies in the future if only information about BOO is needed. These tests are applicable for the majority of patients with lower urinary tract symptoms and suspected BOO. However, urodynamic investigations are still indicated in patients requiring detailed information about the bladder filling and voiding phases and to assess the precise cause of lower urinary tract symptoms.

Development and application of the condom catheter method for non-invasive measurement of bladder pressure

Objectives:A non-invasive method to measure the bladder pressure in males using a condom catheter has been developed. The measurement technique, its validation and limitations, a diagnostic nomogram to non-invasively diagnose bladder outlet obstruction (BOO), and results of large-scale application are discussed.Methods:Modified incontinence condoms are attached to the penis. During voiding the flow of urine is mechanically interrupted. The subsequent maximum pressure in the condom reflects the isovolumetric bladder pressure. The method was validated in a group of 46 patients with lower urinary tract symptoms who were simultaneously studied invasively and non-invasively. Subsequently it was applied in a non-invasive epidemiological study in 1020 healthy males.Results:The reproducibility of the measured isovolumetric bladder pressure is comparable to that of conventional pressure-flow parameters. The measured pressure can be used to diagnose bladder outlet obstruction with a diagnostic accuracy (Area Under receiver operator characteristic curve) of 0.98, which compares most favorably with the area under the curve of 0.79 of Qmax in the same population. During condom catheter measurements, both the involuntary interruption of voiding and the forced diuresis increase post-void residual volume. This increase does not affect the accuracy of the pressure measurements.Conclusions:We conclude that in males bladder pressure can successfully be measured non-invasively using the condom catheter method. By combining the measured volumetric bladder pressure with a separately measured free flow rate, BOO can non-invasively and accurately be diagnosed.

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 (pves.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 (pcuff.int) gives a valid and reliable estimate of invasively-measured pves.isv and when combined with the reading for maximum flow rate obtained during the test (Qmax) 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.

Increased postvoid residual volume after measuring the isovolumetric bladder pressure using the noninvasive condom catheter method

To test, in an ongoing noninvasive longitudinal study in healthy men, whether the condom catheter method (a noninvasive urodynamic test to assess bladder function and bladder outlet obstruction) inhibits bladder function and whether this affects the reliability of the measured isovolumetric bladder pressure (P(ves.iso)). Subjects (754, aged 40-79 years) voided three times, i.e. one free void and two condom measurements. The postvoid residual volume (PVR) was measured after each void using transabdominal ultrasonography. The statistical significance of differences was tested using Wilcoxon rank test and the Mann-Whitney U-test. After free voiding the median (interquartile range) PVR was 18 (37) mL, and independent of the amount of fluid intake. In a subgroup of volunteers, when the free void was done last, the PVR was no different (P = 0.25), suggesting that the bladder did not become exhausted during the protocol. The PVR after two subsequent condom measurements was significantly higher than after free voiding, at 45 (78) and 57 (88) (both P < 0.05), independent of the number of interruptions in voiding. After supplementary fluid intake before the condom measurements, the PVR was double that with a normal fluid intake (P = 0.03). The median P(ves.iso) was 3 cmH(2)O higher in the second condom measurement than in the first (P < 0.05), although this small difference was not clinically relevant. The condom measurement is associated with a significantly higher PVR, partly caused by supplementary fluid intake. This effect was only temporary and did not affect the measured P(ves.iso).

Categorization of Obstruction Using Noninvasive Pressure Flow Measurements: Sensitivity to Change Following Prostatectomy

We determined whether categorizing men with lower urinary tract symptoms using a noninvasive pressure flow nomogram is sensitive to change following the removal of obstruction. A prospective cohort of men undergoing transurethral prostate resection was recruited, of whom 143 (69%) underwent noninvasive pressure flow study using the penile cuff technique before and 4 months following surgery. Cuff pressure required to interrupt voiding, estimated isovolumetric bladder pressure and maximum flow rate were recorded during a single void. Values were plotted on a nomogram categorizing cases as obstructed (upper left quadrant), not obstructed (lower right quadrant) or diagnosis uncertain (upper right and lower left quadrants). Changes in maximum flow rate, cuff pressure required to interrupt voiding and nomogram position following transurethral prostate resection were then analyzed. Transurethral prostate resection resulted in an improved flow rate for all diagnostic groups, which was highest for obstructed cases with a mean +/- SD increase of 11 +/- 6 ml second(-1) (p <0.01). Men categorized with obstruction and those placed in the upper right quadrant showed significant decreases in cuff pressure required to interrupt voiding following transurethral prostate resection with a mean decrease of -45 +/- 35 and -48 +/- 32 cm H(2)O, respectively (p <0.01). The number of cases classified as not obstructed increased from 28 (19%) preoperatively to 114 (80%) after transurethral prostate resection. Sensitivity to change following the removal of obstruction further validates the usefulness of noninvasive measurement of bladder pressure by the penile cuff test and the categorization of obstruction by the noninvasive nomogram. Decreased isovolumetric bladder pressure following transurethral prostate resection may reflect a return to normal detrusor contraction strength.

Variation in Invasive and Noninvasive Measurements of Isovolumetric Bladder Pressure and Categorization of Obstruction According to Bladder Volume

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. 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. 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. 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.

Compensation and decompensation of the urinary bladder muscle studied non-invasively in 827 asymptomatic healthy males

4414 Citation: Journal of Biomechanics 2006; Vol. 39 Suppl. 1, page S391 Compensation and decompensation of the urinary bladder muscle studied non-invasively in 827 asymptomatic healthy males R. van Mastrigt, J.W.N.C. Huang Foen Chung Dept Urology, Erasmus MC, Rotterdam, the Netherlands In the aging male, prostate enlargement often leads to urethral obstruction. In the early phase of obstruction, the increasing resistance of the urethra may be compensated by increasing contractility of the urinary bladder. Later the bladder may decompensate. To be able to apply (surgical) treatment before this irreversible damage occurs, we study the time course of changes in urethral resistance and bladder contractility. Hitherto such a longitudinal study was difficult to perform, as the measurement of bladder pressure was invasive (by insertion of catheters). We developed a non-invasive method of measuring the bladder pressure (Urology 63: 56-60 (2004)). Patients void through an incontinence condom into a flowmeter. The voiding is repeatedly mechanically interrupted, creating a pressure equilibrium between bladder and condom. This enables the isovolumetric bladder pressure to be measured in the condom. We measure this pressure, and also the maximum flowrate and prostate volume 3 times in 5 years in 827 asymptomatic males with rectangular age distribution between 38 and 77 years. Presently we analysed the data from the first evaluation round. The age distribution of the prostate volumes is best described by stating that the range of the prostate volumes increased with age. Between the ages of 38 and 77, the 5th percentile of these volumes increased from 11 to 24 ml, whereas the 95th percentile increased from 43 to 83 ml. Conversely the 5th percentile of the maximum flowrates decreased from 8 to 5 ml/s, whereas the 95th percentile decreased from 43 to 30 ml/s. These two changes were significant according to analysis of variance (p < 0.005). The isovolumetric bladder pressure did not significantly depend on age (p = 0.75), it ranged from approximately 50 to 160 cm H2O in all age groups. In this transverse analysis bladder compensation may have been obscured by age dependent bladder muscle degeneration, as observed in females (Neurourol.Urodyn.11-4: 315-317 (1992)). That will be tested in the follow up.

Bladder volume sensitivity of isovolumetric intravesical pressure

Recently, methods have been introduced for non-invasively measuring the isovolumetric bladder pressure. This pressure can also be measured invasively using a stop test. In itself, the isovolumetric pressure is a measure of urinary bladder contractility, by combining it with maximum urinary flow rate it can be used to diagnose infravesical obstruction. We have studied the (possible) volume dependence of this pressure in order to enhance the accuracy of this type of measurements and to explore its physiological background and possible diagnostic relevance. In 1,020 healthy subjects, recruited for an ongoing longitudinal study of changes in bladder contractility secondary to prostatic enlargement, we measured the isovolumetric bladder pressure using the condom catheter method. In each subject, voiding was repeatedly interrupted. The resulting pressure-volume relations were normalized and averaged. There is an optimum bladder volume for isovolumetric pressure measurements, averaging 264 +/- 122 ml (mean +/- SD). Measurements should be taken at or above the optimum volume. At volumes below the optimum volume, the pressure decreases by approximately 5% for each 10% of volume decrease. At bladder volumes smaller than 247 ml pressure readings in 50% of subjects are suboptimal. The optimum volume for isovolumetric pressure generation is only marginally related to voiding diary parameters. Probably it represents mechanical properties of the bladder, whereas voiding diary parameters more likely represent neurophysiological properties. However, the optimum volume does not reflect the optimum (smooth) muscle length for force generation of the bladder wall: during normal voiding bladder smooth muscle always operates at a suboptimal length for force generation.

Causes for increased residual urine after non-invasive urodynamics using the condom catheter method

4560 Citation: Journal of Biomechanics 2006; Vol. 39 Suppl. 1, page S635 Causes for increased residual urine after non-invasive urodynamics using the condom catheter method S. de Zeeuw, R. van Mastrigt ErasmusMC, Dept Urology, Sector Furore, Rotterdam, The Netherlands The condom catheter method is a non-invasive urodynamic test to assess bladder function. During voiding through a catheter attached to a condom, urinary flow is repeatedly mechanically interrupted. The pressure in the condom then represents the isovolumetric bladder pressure (J Urol 1999; 162: 474-479). Post-void residual (PVR) urine volume is an important quantitative symptom in urology, relating to bladder function. In an ongoing longitudinal study in healthy males, we tested if condom measurements influence PVR. Subjects (n = 461, 40-79 years) voided 3 times: once in a flowmeter, and 2 times using the condom catheter method (Urology 2004; 63: 56-60). PVR was measured after each voiding using transabdominal ultrasound. Statistical significance was tested using Wilcoxon Rank test and Mann Whitney U-test. In the first 181 volunteers mean PVR after free voiding was 63 ml [IQR 3-88]. In the 2 condom measurements this was significantly increased to 109 ml [41-148, p < 0.01] and 123 ml [51-172, p < 0.01]. Analysis of variance showed a significant influence of the number of interruptions of voiding. Limitation of interruptions during the 2 condom measurements in another 121 volunteers, diminished PVR (80 ml [33-105, p = 0.02] and 94 ml [43-128, p < 0.01]). Between the voidings, subjects had to drink extra fluid. Increased water load has been shown to increase PVR (Int J Urol 2004; 11: 1078-1081). Therefore, the increase in PVR after the condom measurements could also have been caused by excessive fluid intake. To test this, we reversed the order of measurements (n = 49). When the condom measurements were done first, PVR (76 ml [13-99]) was significantly smaller than when the free flow preceded the condom measurements. When fluid intake before the first condom measurement was quantified, PVR was augmented after excessive fluid intake compared to normal fluid intake (90 ml [22-109] vs 36 ml [0-60], p = 0.03). PVR after the second condom measurement was larger than after free flow, despite comparable fluid intake (101 ml [32-141] vs 52 ml [14-69], p < 0.01). In conclusion, PVR volume is influenced by both involuntary interruption of voiding and excessive

A NOMOGRAM TO CLASSIFY MEN WITH LOWER URINARY TRACT SYMPTOMS USING URINE FLOW AND NONINVASIVE MEASUREMENT OF BLADDER PRESSURE

Bladder pressure during voiding can be estimated by a noninvasive technique using controlled inflation of a penile cuff. This test provides a valid and reliable estimate of isovolumetric bladder pressure but to our knowledge the role of the test for the routine clinical treatment of patients with lower urinary tract symptoms (LUTS) has yet to be demonstrated. As a first step, we evaluated a proposed nomogram for the diagnosis of bladder outlet obstruction in men with LUTS using noninvasive measurements of pressure and flow. Using a combination of theoretical calculation and experimental data the existing International Continence Society pressure flow nomogram was modified to allow noninvasive measurement of isovolumetric bladder pressure in place of detrusor pressure at maximum urine flow. Accuracy of the nomogram for classifying obstruction was then tested in a group of 144 men with LUTS who underwent an invasive and a noninvasive pressure flow study. The modified nomogram identified men with obstruction with 68% positive predictive value and 78% negative predictive value. Predictive accuracy could be improved by adding an additional criterion of obstruction, that is maximum urine flow less than 10 ml second, whereby an identifiable 69% of all cases could be classified as obstructed (88% positive predictive value) or not obstructed (86% negative predictive value). In the remaining 31% of patients invasive pressure flow studies would provide additional information, although some results would remain equivocal. The proposed nomogram combined with the additional flow rate criterion can classify more than two-thirds of cases without recourse to invasive pressure flow studies. We must now evaluate the usefulness of this classification for the treatment of men with LUTS.

NONINVASIVE ASSESSMENT OF BLADDER CONTRACTILITY IN MEN

Preoperative assessment of detrusor function by pressure flow study (PFS) improves outcome from prostatectomy but is invasive and uncomfortable for the patient. We report on a large scale validation of a novel noninvasive assessment of detrusor contractility. A flexible cuff placed around the penis was inflated automatically during voiding until flow interruption. Cuff pressure at interruption (pcuff.int) reflects isovolumetric bladder pressure (pves.isv), a measure of detrusor contractility. For comparison 151 symptomatic men performed the cuff test with simultaneous PFS monitoring. Test/retest agreement was assessed in 91 subjects who performed a cuff test without PFS on 2 occasions. For the 117 (77%) subjects with an acceptable cuff pressure flow trace, Bland Altman analysis showed that pcuff.int overestimated pves.isv by a mean (s.d.) of 16.4 (27.5) cm H2O, predominantly due to the cuff being positioned below the bladder. For test/retest analysis 52 (57%) of the men who were able to attend twice provided acceptable cuff data on both occasions with a mean (s.d.) difference in pcuff.int of -3.3 (32.0) cm H2O, improving to 0.0 (20.3) cm H2O in a subgroup of 39 subjects who voided more than 150 ml. On questionnaire assessment 121 (80%) subjects preferred the cuff test to PFS. The cuff test gives a valid and reproducible estimate of isovolumetric bladder pressure in a manner acceptable to patients, although test failure and variability of agreement require improvement. The test may be of value in the assessment of urinary symptoms and may aid in patient selection for prostatectomy.