Mastrigt, R. van

Urodynamic Effects of Volume-adjustable Balloons for Treatment of Postprostatectomy Urinary Incontinence (Article)

2013-02-26T00:00:00Z

Objective: To evaluate the urodynamic changes in patients treated with Adjustable Continence Therapy for men (ProACT) for postprostatectomy incontinence and to explore the clinical and urodynamic preimplantation parameters as predictors of clinical outcome. Materials and Methods: Patients underwent urodynamic studies before and after ProACT implantation. ProACT was considered successful if patients used none or 1 dry precautionary pad and nonsuccessful if the patient reported ≥1 wet pad/d. The pre- and postimplantation assessments were retrospectively compared within and between the success and nonsuccess groups. Multivariate logistic regression analysis was performed to investigate the association between the preimplantation variables and the clinical outcomes of ProACT implantation. Results: A total of 49 patients were included, 37 with successful and 12 with nonsuccessful clinical outcome. Postimplantation urodynamic studies were performed a median of 9 months after ProACT implantation. In the successfully treated patients, maximum free flow rate, bladder contractility index, maximum of bladder contractility parameter W, and bladder voiding efficiency were significantly lower after implantation. The detrusor pressure at maximum flow rate, postvoid residual urine volume, and bladder outlet obstruction index were significantly higher. A longer duration of urinary incontinence, the use of >5 pads daily, and a smaller cystometric bladder capacity were all independently associated with nonsuccessful clinical outcome after ProACT implantation. Conclusion: ProACT implantation with successful clinical outcome resulted in greater urethral resistance during voiding and reduced bladder contraction strength. A longer duration of incontinence, the use of >5 pads daily, and a smaller cystometric bladder capacity were independent predictors of unsuccessful clinical outcomes, suggesting ProACT implantation should be considered sooner, rather than later, after conservative treatment of postprostatectomy incontinence has failed.

Response to the future of urodynamics: Non-invasive ultrasound videourodynamics (Letter To Editor)

2010-07-01T00:00:00Z

Age and Volume Dependent Normal Frequency Volume Charts for Healthy Males (Article)

2009-07-01T00:00:00Z

Purpose: We report age and voided volume stratified normal values for voiding diary parameters, including urine production, in a uniform, nonreferred population of 935 healthy male volunteers. Materials and Methods: A total of 935 volunteers kept a 3-day voiding diary and also recorded the time of going to bed and getting up. Additionally, prostate volume was measured using transabdominal ultrasound and the maximum free flow rate was measured with a rotating disc flowmeter. From the diaries we calculated median voided volume and the mean number of voids during the day and night. We also calculated mean urine production in ml per hour during the day and night by assuming constant production between voids. Results: Volunteers voided a median volume of 220 ml 6 times daily and 0.5 times nightly. They produced 83 ml urine per hour during the day and 48 ml per hour during the night. The median maximum flow rate was 16 ml per second and median prostate volume was 31 ml. All diary parameters, free flow rate and prostate volume depended significantly on International Prostate Symptom Score. However, all parameters except urine production during the day depended significantly on age and all except prostate volume depended significantly on voided volume. Conclusions: Values in a subgroup of 788 volunteers with an International Prostate Symptom Score of 10 or less may be considered normal for male voiding diary parameters. Age and voided volume stratified normal values were also derived.

Comparative analysis of the reproducibility and applicability of the condom catheter method for noninvasive urodynamics in two Dutch centers (Article)

2008-09-02T00:00:00Z

OBJECTIVES: We compared the applicability and reproducibility of the condom catheter method for noninvasive urodynamics in two Dutch studies. MATERIALS AND METHODS: A longitudinal study of changes in bladder contractility secondary to benign prostatic enlargement is taking place at the Erasmus MC in Rotterdam. Volunteers aged 38-77 years will be studied three times in 5 years. The first series of measurements has been completed in 1,020 men. A randomized controlled trial to test the effect of additional water intake on bladder function has been completed at the University of Maastricht. 184 subjects aged 55-77 years with International Prostate Symptom Scores of 8-19 were investigated twice in 6 months. Bladder contractility was measured noninvasively with the condom method. Two consecutive measurements were attempted in each subject. Reproducibility was tested according to Bland and Altman and compared by calculating the normalized standard deviation of the differences by dividing by the difference. RES

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

2007-11-06T00:00:00Z

OBJECTIVE: 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 AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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).

Fluid perfused urethral pressure profilometry and Valsalva leak point pressure: A comparative study in a biophysical model of the urethra (Article)

2007-08-01T00:00:00Z

In patient studies the correlation between maximum urethral closure pressure (MUCP) and Valsalva leak point pressure (LPP) is meagre at best (r = 0.22-0.50). We therefore studied the relation between MUCP and LPP in a flexible and extensible model urethra. We applied differently sized pressure zones and different degrees of resistance to a biophysical model urethra by stepwise inflating three types of blood pressure cuff placed around the model. At each degree of resistance we measured detrusor LPP, an in vitro equivalent of Valsalva LPP. Subsequently, we recorded the Urethral Pressure Profile using a water-perfused 5F end-hole catheter at four withdrawal rates and five perfusion rates and calculated MUCP. We tested the dependence of LPP on pressure zone length and MUCP on perfusion rate, withdrawal rate and pressure zone length using analysis of variance. We tested the correlation between LPP and MUCP using Pearson's correlation coefficient and Linear Regression. LPP did not significantly depend on the pressure zone length (P = 0.80) and increased linearly with increasing cuff pressure. MUCP also increased with increasing cuff pressure, however, MUCP significantly depended (P < 0.01) on perfusion rate, withdrawal rate and pressure zone length. MUCP increased with increasing perfusion rate, and decreased with increasing withdrawal rate. In our model urethra MUCP only accurately reflected urethral resistance for a very limited number of combinations of perfusion rate and withdrawal rate. LPP reflected urethral resistance independent of the type of pressure zone.

Accuracy of maximum flow rate for diagnosing bladder outlet obstruction can be estimated from the ICS nomogram (Article)

2007-06-30T00:00:00Z

Fluid perfused urethral pressure profilometry and Valsalva leak point pressure: a comparative study in a biophysical model of the urethra (Article)

2007-06-20T00:00:00Z

Shortening induced effects on force (re)development in pig urinary smooth muscle (Article)

2007-04-24T00:00:00Z

Introduction: When muscle is allowed to shorten during an active contraction, the maximum force that redevelops after shortening is smaller than the isometric force at the same muscle length without prior shortening. We studied the course of force redevelopment after shortening in smooth muscle to unravel the mechanism responsible for this deactivation. Method: In a first series of measurements the shortening velocity was varied resulting in different shortening amplitudes. In a second series, the duration of stimulation before shortening (shortening delay) was varied. In a third series the stimulation was interrupted for a certain duration immediately after shortening. Force, muscle length and stimulation were continuously recorded. Time constants were calculated to describe the rate of force development before and after shortening. Results: With increasing shortening amplitude and with increasing shortening delay, force redevelopment decreased. Redevelopment increased with an increase in the interruption time. After stimulus interruption force redeveloped mono-exponentially with a time constant similar to that of isometric contractions (~ 3 s). Without the interruption of stimulation, the redevelopment of force immediately after shortening was best described by two time constants; one similar to and one about 3-5 times faster than the isometric time constant. Discussion: Force (re)development is caused by a cascade of events leading to the cycling of cross-bridges. In smooth muscle, isometric force development is described by a time constant of about 3 s. Force redevelopment immediately after shortening involves a second process which takes place at a faster rate (time constant about 1 s). We assume that this process is faster due to the immediate availability of cytoplasmic calcium released during active shortening. Deactivation presumably is caused by disorganisation of filaments during shortening.

Re: Noninvasive methods of diagnosing bladder outlet obstruction in men. Part 2: Noninvasive urodynamics and combination of measures (Article)

2007-01-16T00:00:00Z

Is it possible to improve elderly male bladder function by having them drink more water? (Article)

2006-11-23T00:00:00Z

OBJECTIVES: Several animal studies have shown that bladder performance improves as a result of diuresis. Whether increased urine output also has beneficial effects on elderly male bladder function and lower urinary tract symptoms is unknown. METHODS: We performed a randomized placebo-controlled trial of 141 men, 55 to 75 years of age, with moderate lower urinary tract symptoms. The experimental group drank 1.5 L of extra water daily. The control group consumed one tablespoon of placebo syrup daily. After 6 months, we evaluated bladder contractility, voided volumes, and the severity of lower urinary tract symptoms. The actual increase in water consumption was measured using the deuterium urine dilution method. RESULTS: Water consumption in the intervention group increased by 359 mL (95% confidence interval [CI] 171 to 548) per 24 hours compared with the control group. At 6 months, no statistically significant effect was found in the maximal flow rate (0.9 mL/s, 95% CI -0.4 to 2.2) compared with placebo. A statistically significant effect was found for bladder pressure (20 cm H2O, 95% CI 6 to 34) and bladder wall stress (1.9 N/cm2, 95% CI 0.3 to 3.5). In addition, it showed that the experimental group had greater maximal (44 mL, 95% CI -1 to 90) and average (26 mL, 95% CI 1 to 51) voided volumes per urination. The subjective effect parameters improved in both groups, but no statistically significant differences were found between the two groups. CONCLUSIONS: It seems possible to improve some aspects of male bladder function by drinking more water. However, the effects are too small to be clinically relevant

Bladder volume sensitivity of isovolumetric intravesical pressure (Article)

2006-08-10T00:00:00Z

AIMS: 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. MATERIALS AND METHODS: 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. RESULTS AND CONCLUSIONS: 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

Shortening induced effects on force (re)development in pig urinary smooth muscle (Article)

2006-07-01T00:00:00Z

INTRODUCTION: When muscle is allowed to shorten during an active contraction, the maximum force that redevelops after shortening is smaller than the isometric force at the same muscle length without prior shortening. We studied the course of force redevelopment after shortening in smooth muscle to unravel the mechanism responsible for this deactivation. METHOD: In a first series of measurements the shortening velocity was varied resulting in different shortening amplitudes. In a second series, the duration of stimulation before shortening (shortening delay) was varied. In a third series, the stimulation was interrupted for a certain duration immediately after shortening. Force, muscle length and stimulation were continuously recorded. Time constants were calculated to describe the rate of force development before and after shortening. RESULTS: With increasing shortening amplitude and with increasing shortening delay, force redevelopment decreased. Redevelopment increased with an increase in the interruption time. After stimulus interruption force redeveloped mono-exponentially with a time constant similar to that of isometric contractions (approximately 3s). Without the interruption of stimulation, the redevelopment of force immediately after shortening was best described by two time constants; one similar to and one about 3-5 times faster than the isometric time constant. DISCUSSION: Force (re)development is caused by a cascade of events leading to the cycling of cross-bridges. In smooth muscle, isometric force development is described by a time constant of about 3s. Force redevelopment immediately after shortening involves a second process which takes place at a faster rate (time constant about 1s). We assume that this process is faster due to the immediate availability of cytoplasmic calcium released during active shortening. Deactivation presumably is caused by disorganization of filaments during shortening.

Urodynamica ? Urodynamica ! (Inaugural Lecture)

2006-06-06T00:00:00Z

Rede, in verkorte vorm uitgesproken bij de aanvaarding van het ambt van bijzonder hoogleraar in de Fysica van de Urinewegen aan het Erasmus MC, faculteit van de Erasmus Universiteit Rotterdam, op 6 juni 2006

Is the impaired flow after hypospadias correction due to increased urethral stiffness? (Article)

2006-05-18T00:00:00Z

Purpose: A low flow rate without clinical symptoms is commonly found in boys after hypospadias correction. Urethral calibration usually shows no abnormalities. We investigated whether this flow rate impairment might be caused by increased neo-urethral wall-stiffness. Methods: From Polyvinyl Alcohol cryogel two models of the urethra were made, a hypospadias model and a control model. Both models had a constant and equal inner diameter and equal compliance. The hypospadias model had a less compliant distal segment mimicking the distal neo-urethra after hypospadias correction. In both models flow rate was recorded as a function of bladder pressure. To test whether the length of the less compliant segment had an effect on the flow rate, both models were shortened by cutting off 1 cm segments. Results: In a physiological range of bladder pressures (10 - 130 cmH2O) the mean flow rate(± 1sem) in the hypospadias model was 2.8± 0.3 ml/s, significantly lower (p < .05) than in the control model (5.4 ± 0.6 ml/s). Shortening of the hypospadias model showed some increase in flow rate, however not statistically significant. In the control model there was also no significant variation in flow rate. Conclusion: We showed that a low compliant segment of a urethral model reduces the flow rate. Extrapolating these results to asymptomatic boys with a low urinary flow rate after hypospadias repair might justify a watchful waiting policy.

A Biophysical Model of the Male Urethra: comparing viscoelastic properties of PolyVinyl Alcohol urethras to male pig urethras. (Article)

2006-04-12T00:00:00Z

Aims: We aim at developing a non-invasive method for grading and diagnosing urinary bladder outlet obstruction, based on noise recording with a perineal contact microphone during voiding. We found that the noise production during voiding depends amongst others on the viscoelastic properties of the urethral wall. To further test our method, we need a realistic biophysical model of the male urethra. Methods: We made various model urethras with different viscoelastic properties from a 10% aqueous solution of PolyVinyl Alcohol cryogel. We measured the viscoelastic properties of each model and compared them to those of the male pig urethra. The male pig urethra was used, as it is physiologically comparable to the human male urethra. The viscoelastic properties of both model and pig urethras were measured by applying strain to the urethral wall in a stepwise manner and recording the pressure response. We fitted the step-response of a mechanical model to this pressure response and derived the viscoelastic properties from the coefficients of this response. Results: A uniform model urethra that was freeze-thawed three times, with a Y-shaped flow channel was found to best represent the male pig urethra. Conclusion: We consider the three times freeze-thawed model urethra with a Y-shaped flow channel the best model of the human male urethra. And we therefore use this model urethra for studying the relation between noise recording during urine flow and the degree of bladder outlet obstruction.

Sacral neuromodulation in women with idiopathic detrusor overactivity incontinence: decreased overactivity but unchanged bladder contraction strength and urethral resistance during voiding (Article)

2006-02-14T00:00:00Z

PURPOSE: We evaluated the effect of sacral (S3) nerve neuromodulation on voiding in women with idiopathic detrusor overactivity incontinence. MATERIALS AND METHODS: Urodynamic measurements in all patients implanted in 1990 to 2003 were reconsidered. Patients were included if these measurements, which were done at baseline and after 6 months, could be analyzed completely and reliably. Maximum detrusor pressure, amplitude of the highest involuntary detrusor contraction and end fill volume were used as parameters characterizing the degree of detrusor overactivity. Urethral resistance and bladder contraction strength during voiding were characterized by the bladder outlet obstruction index, the urethral resistance factor, average pressure, the slope of the low pressure side of the pressure flow plot, the bladder contractility index and the bladder contraction strength parameter. RESULTS: A total of 33 women were included. Detrusor overactivity parameters were significantly improved at followup. In addition, the supine position of the patient during filling in followup measurements proved less provocative with respect to overactivity than the standing position in the majority of measurements at baseline. Consequently bladder volumes at which voiding was initiated were considerably higher at followup. Changes in the parameters characterizing urethral resistance and bladder contraction strength during voiding were not unambiguous. However, exactly those parameters that appeared volume independent in a previous study were not significantly different. CONCLUSIONS: Our study confirmed the depressant effect of sacral (S3) nerve neuromodulation on detrusor overactivity. No effect on urethral resistance and bladder contraction strength during voiding could be demonstrated using volume independent parameters

Epidemiological aspects of recruitment of male volunteers for non-invasive urodynamics (Article)

2006-01-01T00:00:00Z

We studied epidemiological aspects of recruitment of volunteers for a non-invasive urodynamic study. MATERIALS AND METHODS: 9,236 volunteers were invited by 20 general practitioners (GPs), using two different recruitment methods, i.e. by mail only, or during a subsequent visit to the GP's office. Factors influencing the response rates were analyzed. We also tested how much the recruited population of volunteers differed from the general population, by comparing it to another, proven representative study carried out earlier in 1,662 subjects. RESULTS: In the recruited population the prostate volumes were not significantly different from the proven representative study, but the symptom score was statistically significantly higher, although the difference was so small it may be called clinically irrelevant. Recruitment of volunteers in two steps, i.e. asking them first to visit the GP's office, and inviting them there to visit the outpatient clinic, rather than directly inviting them (in writing) to the clinic seemed to lead to a higher response, although this effect could not be statistically discriminated from the difference in response rates between GPs. CONCLUSION: The population recruited was not urologically different from the general population. The response depended on age, being highest around the age of 60, and increased with social economic status. It also depended on the GP who recruited the subjects, and/or on the recruitment method.

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

2006-01-01T00:00:00Z

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

2006-01-01T00:00:00Z

Development of a computational model urethra to study perineal noise as a diagnostic marker for prostatic obstruction (Article)

2006-01-01T00:00:00Z

Variation in noise recorded distally to a urethral obstruction related to cross-sectional area and flow pattern (Article)

2006-01-01T00:00:00Z

Contractile properties of the proximal urethra and bladder in female pig: morphology and function (Article)

2005-11-24T00:00:00Z

AIMS: To compare the contractile properties of proximal urethral and bladder muscle of the female pig. MATERIALS AND METHODS: In two proximal segments (I and II) of the urethra, small muscle bundles were excised to measure the force-length (maximum force) and the force-velocity (unloaded shortening velocity) relation using the stop-test. The rate of force development was calculated using phase plots. Contractile properties of urethral and bladder segments were statistically compared using the Mann-Whitney U-test. Immunohistochemical staining of whole circumference urethral cross sections was used to identify the location of smooth and striated muscle fibres. RESULTS: On isometric force development, the urethral muscle bundles revealed a fast ( approximately 0.5 sec) and a slow ( approximately 2.1 sec) time constant, whereas in bladder only a slow ( approximately 2.3 sec) component was measured. On average, isometric force was highest in bladder. The length range over which force was produced was smallest in urethral segment II, followed by urethral segment I and finally bladder. The unloaded shortening velocity was 0.15, 0.25 and 0.35 1/sec, respectively. Histological preparations showed that smooth as well as striated muscle was present in proximal urethra. In urethral muscle bundles, spontaneous contractions were measured with a frequency of 0.4 Hz. CONCLUSIONS: Differences in contractility found between urethra and bladder may be ascribed to the presence of striated muscle in the proximal urethra. The regulation of tone and spontaneous contractions may be part of the continence mechanism in the female pig urinary tract

Perineal noise recording as a non-invasive diagnostic method of urinary bladder outlet obstruction: a study in polyvinyl alcohol and silicone model urethras (Article)

2005-05-10T00:00:00Z

AIMS: At present, an invasive pressure flow study is recommended to diagnose urinary bladder outlet obstruction. This method induces the risk of urinary tract infection and urethral trauma. We studied perineal noise recording as an alternative, non-invasive diagnostic method in three flexible/extensible model urethras and two silicone tubes. METHODS: The flexible/extensible model urethras were made of a 10% aqueous solution of polyvinyl alcohol (PVA) and differed in wall- stiffness, the silicone tubes differed in diameter and wall-thickness. Three degrees of obstruction were applied by inflating a cuff placed around the PVA-urethras and by compressing the silicone tubes with an adjustable clamp. Noise, produced during flow, was recorded at three positions distal to the obstruction using a piezoceramic contact microphone. RESULTS: The average amplitude of the noise and the essential frequency of the power spectrum of each noise recording depended significantly on the degree of obstruction, the position of the microphone and the wall-stiffness in PVA-urethras and the diameter in silicone tubes. CONCLUSIONS: Based on the results of this study perineal noise recording shows good potential as an alternative method for diagnosing bladder outlet obstruction

Reply to: Comments on the non-invasive measurement of bladder pressure developed by Pel et al. 2004. Neurourol Urodyn 23:383-4 (Article)

2005-02-04T00:00:00Z

Contractile properties of inner and outer smooth muscle bundles from pig urinary detrusor (Article)

2005-01-25T00:00:00Z

Like in the human detrusor, the pig urinary detrusor muscle consists of two layers: compactly arranged smooth muscle bundles on the mucosal side (inner layer) and loosely arranged smooth muscle bundles on the serosal side (outer layer). The contractile properties of muscle bundles of both layers were measured using the stop test followed by an isometric contraction. Total and passive forces were measured in ten muscle bundles from the inner and outer muscle layers. Active force was defined as the difference between total and passive force. The curvature and the unloaded shortening velocity of the force-velocity relation were calculated from the shortening forces measured during the stop test. The rate of force development was calculated from the isometric contraction. Differences in contractile properties between both layers were pairwise tested using the Wilcoxon Signed Ranks test. Percentage wise, the outer layer muscle bundles produced the highest active isometric force. The shortening forces were also higher in the outer layer bundles. As a result, both the curvature and the unloaded shortening velocity, derived from the average force-velocity relations fitted to the data sets, were higher in the muscle bundles from this layer. Finally, the outer layer muscle bundles contracted significantly faster than those of the inner layer. Muscle bundles from the outer layer of pig detrusor were found to be faster and stronger (more phasic) than the weaker and slower (more tonic) bundles from the inner layer, suggesting that during bladder contraction the outer layer of the detrusor does more work than the inner layer

Afferent bladder nerve activity in the rat: a mechanism for starting and stopping voiding contractions (Article)

2004-11-02T00:00:00Z

The objective of this work was to study the relation between afferent bladder nerve activity and bladder mechanics and the mechanisms that initiate and terminate bladder contractions. Bladder nerve activity, pressure and volume were recorded during the micturition cycle in the rat. The highest correlation was found between afferent nerve activity and stress (pressure x volume). Afferent nerve activity depended linearly on stress within 6%, and both slope and offset were independent of the bladder-filling rate. The levels of afferent bladder nerve activity at the onset and cessation of efferent firing to the bladder were highly reproducible with coefficients of variation of

Correlation of non-invasive urodynamics with International Prostate Symptom Score (IPSS) and prostate volume (Article)

2004-10-07T00:00:00Z

AIM: To study the correlation between non-invasive urodynamic data, the International Prostate Symptom Score (IPSS) and the prostate volume. MATERIALS AND METHODS: Data of 667 healthy volunteers participating in a longitudinal study of changes in urinary bladder contractility secondary to BPE were analyzed. The prostate volume was assessed by transabdominal ultrasonography. Uroflowmetry followed to verify if a minimum free flow rate of 4.5 ml/sec could be achieved. While (re)filling the bladder by drinking, the subjects completed the Dutch version of the IPSS. Next, the bladder pressure was non-invasively measured using the condom catheter method. The urethral resistance (URR) was calculated from the maximum condom pressure and the maximum free flow rate. RESULTS: The IPSS ranged from 0 to 29, (6.1 +/- 4.8) (mean +/- SD), whereas the prostate volumes ranged from 8 to 140 cm3, (34 +/- 18). Twenty eight percent (185/667) of the subjects had a non-invasively quantified high URR and a significantly higher IPSS (7.3 +/- 5.2) than those with a low URR (IPSS (5.7 +/- 4.6)), Mann-Whitney U-test: P < 0.001. The IPSS and the URR were significantly correlated, Spearman's rho (rho) = 0.20, P < 0.001. A significant difference between the prostate volumes, 36 +/- 21 cm3 in the high URR versus 33 +/- 17 cm3 in the low URR group, was not found, P = 0.18. CONCLUSIONS: A weak though statistically significant correlation was found between the non-invasively quantified URR and the IPSS. This suggests that an elevated resistance is a necessary, but not a sufficient condition for lower urinary tract symptoms (LUTS). No correlation was found between the URR and the prostate volume

Prostate volume ultrasonography: the influence of transabdominal versus transrectal approach, device type and operator (Article)

2004-08-13T00:00:00Z

OBJECTIVES: We conduct a longitudinal non-invasive study of changes in urinary bladder contractility secondary to benign prostatic enlargement. In that study, the prostate volume is estimated by transabdominal ultrasonography. The accuracy of those measurements was verified by comparison of transabdominal to transrectal stepwise planimetric ultrasonography as the gold standard. Also, two different transabdominal devices used were compared, and the influence of different operators was studied. MATERIALS & METHODS: Two series of measurements in 100 patients each were done. In the first series, transabdominal and transrectal sonography were pairwise compared in each patient. In the second series, transabdominal measurements were done with two devices (a hospital Aloka SSD-1700 and a portable Aloka SSD-900). Transrectal scannings were done by three investigators whilst all transabdominal scannings were done by one. Regression graphs, ratio plots and statistical analyses of the data quantified the reproducibility of different methods, observers and device types. RESULTS: In the transrectal-transabdominal series of prostate volume measurements (in cm3), the Pearson correlation coefficient was 0.84 (p < 0.001), the mean of the means was 51.8 +/- 23.0 (mean +/- S.D.), and the mean of the differences was 1.0 +/- 1.4. In the series with two devices, the Pearson correlation coefficient was 0.73 (p < 0.001), the mean of the means was 31.0 +/- 10.9, and the mean of the differences was 1.0 +/- 1.3. CONCLUSION: No statistically significant differences were found between the transabdominal- transrectal ultrasonography, two different transabdominal devices nor between different observers. However, for those using these measurements in everyday clinical practice, it is worth to point out that in our data a transabdominal scan and a transrectal scan in the same patient, on the same day, differed more than 30% in one fourth of the patients and that two transabdominal scans in the same patient (with two different devices, on two different days) differed more than 30% in every fifth patient

Re: Noninvasive techniques for the measurement of isovolumetric bladder pressure. (Article)

2004-07-13T00:00:00Z

ICS standard for digital exchange of urodynamic study data (Article)

2004-04-21T00:00:00Z

INTRODUCTION. In 1997, the ICS standard for digital exchange of pressure- £ow study data was published (Neurourol. Urodyn. 1997;16: 9^18) with the intention of enabling the exchange of urodynamic data and curves between equipment of di¡erent manufacturers. Initially, the purpose of the standard was to make it possible to carry out multi-centre trials with di¡erent brands of equipment in the di¡erent centres, but with central data processing. The standard makes it possible to copy a pressure-£ ow study performed with a speci¢c brand of urodynamic equipment to a transportable medium, for instance a £oppy disc or e-mail, and subsequently import it into the PC of another brand of urodynamic equipment. Not only the resulting parameters, such as the maximum £owrate are copied, but also the tracings. Re-analysis of the study on the second set-up is therefore possible.Up to now, import and export of ICS standard urodynamic ¢les has been implemented in the equipment of Andromeda Medical Systems, Medtronic Functional Diagnostics and Medical Measurement Systems. These implementations have been veri¢ed by the authors. Lifetech and Laborie have both announced that they will support the standard. This document updates the standard, listing revisions and additions.The revised version of the standard will be posted in its entirety on the ICS web site: www.icso⁄ce.org

Pathophysiological aspects of bladder dysfunction: a new hypothesis for the prevention of 'prostatic' symptoms (Article)

2004-02-21T00:00:00Z

This article reviews the literature on the pathophysiology of male lower urinary tract symptoms (LUTS) with the intention of developing a new preventive intervention for this bothersome disease. Traditionally, male voiding dysfunction has been thought to arise from bladder outlet obstruction (BOO) caused by prostatic enlargement. Many years of research, however, have shown that a clear relationship between the size of the prostate and the occurrence or severity of symptoms is doubtful. Because of its crucial role in urination, it is increasingly being accepted that the clinical manifestation of voiding dysfunction relies on the functional behaviour of the bladder. Several animal studies have shown that bladder performance can be improved by increasing urine output. Contrary to alterations observed in pathologic situations, an increased urine output provides a physiologic stimulus for animal bladder function improvement. We hypothesise that a trained bladder should be less susceptible to the harmful effects of ageing and obstruction. Future symptoms may thus be prevented. In humans an increased urine output can be achieved by drinking additional water, which could be an adequate preventive intervention

Applicability and reproducibility of condom catheter method for measuring isovolumetric bladder pressure (Article)

2004-01-31T00:00:00Z

OBJECTIVES: To report on the applicability, reproducibility, and adverse events of the noninvasive condom catheter method in the first 730 subjects of a longitudinal survey of changes in urinary bladder contractility secondary to benign prostatic hyperplasia, in which 1300 men will be evaluated three times in 5 years using this method. METHODS: Subjects were recruited by general practitioners, general publicity, and e-mail. Only those meeting the study criteria were entered in the study. If the free flow rate exceeded 5.4 mL/s, at least two consecutive condom pressure measurements were attempted using the condom catheter method. The condom pressure measured reflected the isovolumetric bladder pressure, a measure of urinary bladder contractility. The reproducibility of the method was quantified by a difference plot of the two maximal condom pressures measured in each subject. RESULTS: In 618 (94%) of 659 eligible participants, one condom pressure measurement was completed; two measurements were done in 555 (84%). The maximal condom pressure ranged from 28 to 228 cm H2O (overall mean 101, SD 34). A difference between the two pressures of less than +/-21 cm H2O was found in 80%. The mean difference was -1 cm H2O (SD 18), significantly different from 0. Some adverse events such as terminal self-limiting hematuria were encountered. CONCLUSIONS: The condom catheter method is very suitable for large-scale use. It has a success rate of 94% and a reproducibility comparable to that of invasive pressure flow studies

Weak correlation between bladder outlet obstruction and probability to void to completion (Article)

2003-10-01T00:00:00Z

OBJECTIVES: To investigate the weak correlation between bladder outlet obstruction (BOO), as diagnosed using the provisional International Continence Society nomogram for the definition of BOO in men, and postvoid residual urine volume. METHODS: The relationship between voiding to completion and several indexes for bladder outlet resistance and bladder contractility was studied in 131 pressure flow studies in male patients using multivariate logistic regression analysis. RESULTS: The International Continence Society nomogram and the related BOO index weakly predict for postvoid residual urine volume (areas under the receiver operating characteristic curve 0.63 and 0.64, respectively). The BOO index primarily measures bladder outlet resistance. If the nomogram or BOO index is augmented with bladder contractility information, the postvoid residual urine volume can be predicted significantly better (eg, area under the receiver operating characteristic curve [0.89] for the combination of the BOO index and bladder contractility information). CONCLUSIONS: The weak correlation between BOO and postvoid residual urine volume is related to the fact that emptying the bladder to completion depends on bladder contractility, as well as bladder outlet resistance. It is possible to estimate the probability to void to completion quite accurately on the basis of bladder outlet resistance and bladder contractility. We named this probability "relative bladder outlet resistance." A high probability of a postvoid residual urine volume may be assumed to indicate "relative BOO." By its very nature, the correlation between "relative BOO" and postvoid residual urine volume is good

Causes for variability in repeated pressure-flow measurements (Article)

2003-05-09T00:00:00Z

OBJECTIVES: To study the causes for the variation between measurements, which is considerable, in maximal flow rate (Qmax) and the associated detrusor pressure (PdetQmax). Because of the central role of Qmax and PdetQmax in the diagnosis of bladder outlet obstruction, this is reason for concern. METHODS: Spectral analysis was carried out on two consecutive urodynamic measurements in 131 patients. The parameters for bladder outlet resistance and bladder contraction strength were determined, and difference plots were made to study the systematic variations. Logistic regression analysis was used to study whether the differences represent true changes of the function of the lower urinary tract. RESULTS: Signal components in the detrusor pressure and the flow rate signal with frequencies of 1 Hz or greater may be considered noise. Filtering out these frequencies changes the estimates of Qmax and PdetQmax, but not the between-measurement difference in them. Bladder contractility and bladder outlet resistance were systematically lower in the second measurement. Both the systematic and nonsystematic between-measurement variations were statistically significant predictors for postvoid residual urine volume. CONCLUSIONS: The nonsystematic between-measurement variability in Qmax and PdetQmax apparently reflects true variability in the physiologic state of the bladder outlet. It therefore does not discredit the pressure-flow study as the preferred method in the diagnosis of bladder outlet obstruction. Rather, the pressure-flow study is the only currently available method to study and quantify the apparent within-patient variability in bladder outlet resistance and bladder contractility

A flow rate cut-off value as a criterion for the accurate non-invasive measurement of bladder pressure using a condom-type catheter (Article)

2003-05-07T00:00:00Z

We developed a condom-type catheter to non-invasively measure the bladder pressure during interruption of the flow rate. The aim of the present study was to establish a minimum flow rate value at which a reliable bladder pressure measurement can be made with this catheter. We reanalysed data from 43 patients who completed a pressure-flow study and a non-invasive test. The patients voided without straining. During the test, we simultaneously measured the bladder pressure (invasively) and the condom pressure (non-invasively). The pressure increase in the condom after interruption of the flow rate was analysed in 40 of the 43 patients. A plot of the difference between the bladder pressure and the maximum condom pressure as a function of the flow rate revealed that in 70% of the patients who voided with a maximum flow rate exceeding 5.4 ml/s, the condom pressure accurately reflected the bladder pressure (+/-14 cmH2O). We conclude that to accurately and non-invasively measure the bladder pressure with a condom-type catheter, the maximum flow rate should exceed 5.4 ml/s.

Bladder outlet resistance (Article)

2003-02-11T00:00:00Z

PURPOSE: We developed a method to objectively compare methods for the quantification of bladder outlet resistance. MATERIALS AND METHODS: We studied unselected voiding cystometries from 131 male patients. Several models proposed for bladder outlet resistance were fitted to the lowest monotonically increasing part (bottom) of the pressure flow plots. In conjunction with a parameter for bladder contractility, the model parameters were used as predictors of post-void residual greater than 20% of filled volume. RESULTS: The pressure decrease in relaxed bladder outlet was best described by a linear function of the flow rate. The flow rate independent and dependent parts of that function were statistically significant predictors for residual. However, they could be combined into 1 index that was as efficient as the 2 numbers separately in predicting residual. This index is the average pressure of the bottom of the pressure flow plot. CONCLUSIONS: We describe how different models for the quantification of bladder outlet resistance can be compared objectively on the basis of their ability to predict a significant post-void residual. Using this criterion in an unselected group of measurements, the average pressure of the bottom of the pressure flow plot performed best as an index for bladder outlet resistance quantification. It combines (or weights) 2 components (dependent and independent flow rates) without losing its power to predict post-void residual

Mechanical properties of (urinary bladder) smooth muscle (Article)

2002-10-05T00:00:00Z

This short overview of the mechanical properties of smooth muscle focusses on the force-velocity relation of (mainly pig urinary bladder) smooth muscle, and its dependence on the length of the muscle and its degree of activation. Also the response of the muscle to length and force changes at a rate beyond the physiological range is discussed. The force-velocity relation of this type of muscle can be approximated by the hyperbolic Hill equation, with a normalised maximum shortening velocity in the order of 0.25 muscle lengths/s. As in striated muscle, the maximum isometric force depends on the stretched muscle length and shows a maximum at a certain length. Interestingly, smooth muscle does not normally seem to operate at this length, but far below it. Both the isometric force and the unloaded shortening velocity depend on the degree of activation of the muscle, and so does the 'curvature' of the Hill equation. The series elasticity of the muscle, which can be measured by applying length changes at a rate beyond the physiological shortening velocity, is found partly in the cross-bridges, and partly external to these. An isometric quick release of 4-10% of the muscle length is necessary to remove all tension, depending on the total force exerted by the muscle. Force recovery after such a release is biexponential in a 700 ms window. The slowest component of this recovery, with a time constant in the order of 0.45 s is mainly associated with cycling of the cross-bridges, the fastest with the external series (visco)elasticity. Isometric force development has a time constant in the order of 3 s. indicating that excitation-contraction coupling rather than cross-bridge cycling is rate limiting in this process

Relative bladder outlet obstruction (Article)

2002-07-20T00:00:00Z

PURPOSE: Currently bladder outlet obstruction in males is defined by the provisional International Continence Society nomogram which is partly based on expert opinion and partly on measurements before and after transurethral prostate resection. Recently there has been some interest in the development of a similar nomogram for females. MATERIALS AND METHODS: We studied the possibility of defining bladder outlet obstruction based on a sign that it causes, namely post-void residual urine. RESULTS: The probability of relative post-void residual urine exceeding 20% of bladder capacity was modeled in males and females using 1 parameter, that is URA/w20 or the ratio of the obstruction parameter urethral resistance factor (URA)-to-the bladder contractility parameter Watts factor at 20% (w20). URA/w20 represents relative bladder outlet resistance or bladder outlet resistance normalized to bladder contractility. Above a threshold of URA/w20 = 6.8 in females and 8.2 in males a relative post-void residual exceeding 20% was noted in 90% of measurements. These thresholds may be used to define relative obstruction. The provisional International Continence Society nomogram for obstruction in males was transformed into an identical nomogram for females by equating the probabilities of post-void residual urine in each gender. The latter differed from that in men, in that the lines demarcating the zones were horizontal or flow rate independent but the intercepts were approximately the same at 20 and 40 cm. water. CONCLUSIONS: Instead of defining obstruction as an absolute level of bladder outlet resistance we suggest that it is better to define it relatively, that is as a level of bladder outlet resistance that depends on bladder contractility

Development of a non-invasive strategy to classify bladder outlet obstruction in male patients with LUTS (Article)

2002-02-22T00:00:00Z

To diagnose bladder outlet obstruction in male patients with lower urinary tract symptoms (LUTS), it is necessary to measure the bladder pressure via a transurethral (or suprapubic) catheter. This procedure incurs some risk of urinary tract infection and urethral trauma and is sometimes painful to the patient. We developed an external condom catheter to measure non-invasively the bladder pressure and developed a strategy to classify bladder outlet obstruction (BOO) based on this measurement. Seventy-five patients with a wide range of urological diagnoses underwent a pressure-flow study followed by a non-invasive study. We tested five different strategies to classify the patients using the provisional International Continence Society (ICS) method for definition of obstruction as the gold standard. Leakage of the external catheter occurred in eight (40%) of the first 20 tested patients. In the remaining 55 patients, only five (9%) of the measurements failed because of leakage. Of the 75 patients, 56 were successfully tested non-invasively. According to the ICS nomogram, the PFS showed that 22 of these patients were non-obstructed, 12 patients were equivocal, and 22 patients were obstructed. Ten of these 56 patients strained, and we found that the relatively high abdominal pressures in these patients were not reflected in the externally measured bladder pressure. Of the remaining 46 patients, 12 of 13 non-obstructed patients and 30 of 33 combined equivocal and obstructed patients could be correctly classified. We developed a simple, non-invasive classification strategy to identify BOO in those male patients who did not strain during voiding

Development of a low-cost flow meter to grade the maximum flow rate (Article)

2002-02-09T00:00:00Z

We developed an inexpensive flow meter to grade the maximum flow rate of individuals at locations other than the clinical setting. This flow meter consists of a funnel connected to a collecting tube with several exit ports. Urine directed into this tube flows through one or more ports and is collected in a measuring cup to measure the voided volume. The number of ports emitting the liquid is a measure for the flow rate. We made four experimental models to test and compare some of the physical properties. One of these models was selected as a prototype and was tested in five healthy volunteers. All volunteers voided repeatedly in a standard rotating disk flow meter and in this prototype to test its accuracy. The response time of the experimental models depended on the outlet resistance of the exit ports and the volume of the collecting tube. In two models, this time was comparable with that of currently used volume-based electronic flow meters (approximately 2 seconds). In healthy volunteers, the maximum flow rates graded with the selected prototype and those measured with the rotating disk flow meter showed good agreement (difference=0.4+/-2.6 mL/s; mean+/-SD). The low-cost flow meter may be used repeatedly to grade the maximum flow rate at private and familiar locations (for example, at home), which may increase the accuracy of evaluating the urinary stream in patients with lower urinary tract symptoms

Urodynamic follow-up of experimental urethral obstruction in individual guinea pigs (Article)

2001-12-18T00:00:00Z

It is unknown whether changes in bladder function due to urethral obstruction follow a specific sequence. To answer this, we adapted a small animal model to allow repeated complete pressure-flow studies, enabling individual follow-up of changes in bladder function on urethral obstruction. Obstruction was induced in guinea pigs by placing a silver ring around the urethra. Urodynamic studies were repeated under anesthesia with ketamine/xylazine. Bladders were filled and bladder pressure measured through a single suprapubic catheter. Urine flow rate was measured using an ultrasound probe around the penis. Accurate measurements of bladder pressure and urine flow rates were obtained at 1-week intervals for 11 weeks in individual guinea pigs. In the control animals, the urodynamic parameters did not show significant changes. In the obstructed group, urethral resistance (P(low,ave)) increased from 20 to 35 cm H(2)O after 4 weeks and remained at that level. The maximum flow rate (Q(max)) increased from 0.17 to 0.24 mL/s after 2 to 3 weeks. After this peak, it gradually decreased to lower than the starting value after 10 to 11 weeks. The pressure at maximum flow rate (p(Qmax)) increased from 24 to 47 cm H(2)O after 6 to 7 weeks and thereafter declined. During weeks 1 through 4 of obstruction, unstable contractions were seen. All animals followed a similar sequence of patterns but at variable rates. Our animal model allows complete urodynamic follow-up of individual animals with urethral obstruction. We observed a specific sequence of changes in urodynamic patterns and parameters of bladder function

Measurement of urinary flow rate using ultrasound in young boys and infants (Article)

2001-08-08T00:00:00Z

PURPOSE: We present a technique for measuring urinary flow rates with ultrasound in male infants and children. MATERIALS AND METHODS: Urinary flow rate was measured simultaneously by an ultrasound probe placed around the base of the penis and by a funnel with a rotating disk at the bottom in 30 boys with a mean age of 6.7 years (range 4.5 to 10.5), and by ultrasound in 8 infants with a mean age of 10 months (range 1 to 28). Voided volume was measured with a graded cylinder or calculated from the weight change of diapers in infants. Ultrasound and rotating disk maximum flow rates were calculated. The ultrasound signal was calibrated by comparing the collected voided volume to the area under the curve for that void. The volume calculated from the rotating disk flow rate curve was also compared with the collected volume. RESULTS: Both methods yielded similar flow curves. However, ultrasound maximum flow rate significantly exceeded rotating disk maximum flow rate (13 +/- 6 ml. per second, range 5 to 22 versus 10 +/- 4 ml. per second, range 4 to 21, t test p <0.001). The underestimation of the flow rate by the rotating disk method may have been due to adherence of urine to the funnel wall. Rotating disk maximum flow rate was lower and voided volume was underestimated by up to 50% (average 15 +/- 2%) in 21 cases. Ultrasound maximum flow rate averaged 6 +/- 3 ml. per second (range 3 to 11.6 [oldest infant]) in the 8 infants. CONCLUSIONS: Urinary flow rates can be measured accurately using ultrasound in boys who produce small volumes and/or who are not toilet trained and also in infants. In future studies ultrasound will be applied to subsets of male infants with bladder dysfunction

Length dependence of the contractility of pig detrusor smooth muscle fibres (Article)

2001-06-09T00:00:00Z

Evidence on the length dependence of the contraction velocity of smooth muscle fibres is contradictory. Nevertheless, a thorough understanding of this dependence is essential for a correct urodynamic diagnosis of voiding problems. We studied muscle fibres of pig urinary bladders (n = 23). Force-velocity relations were measured at different muscle lengths with a stop test technique. This method involves measuring force generation of electrically stimulated muscle fibres during controlled shortening from a pre-shortening length at a pre-set velocity to a fixed stop-length. We normalized the length dependence of the measured properties to slack length, optimum length (the length at maximum isometric force generation), and passive force. Isometric force was found to be length dependent with an optimum length of 290+/-68% of the slack length (n = 11, P < 0.05). The maximum shortening velocity was 0.37+/-0.14 s(-1) related to the slack length and 0.13+/-0.05 s(-1) related to the optimum length and was not length dependent (n = 16, P < 0.05). Slack length is preferable to normalize the length dependence of smooth muscle

Intracellular electrical activity in human urinary bladder smooth muscle: the effect of high sucrose medium (Article)

2001-06-01T00:00:00Z

Introduction: The primary key to pharmacotherapy of bladder instability is in the excitation-contraction coupling of detrusor smooth muscle cells. To study this process, simultaneous recordings of mechanical and electrical activity are required. However, recording of mechanical activity induces movement, which may affect the quality of intracellular recordings. Materials and Methods: We therefore compared the electrical activity of human detrusor smooth muscle cells in normal Krebs' solution and in a hypertonic solution, which immobilizes the tissue, enabling us to study the effect of movement on the membrane potential. Carbachol and KCl were applied to induce contractions. Results: Sucrose in the medium made the tissue rigid and abolished its movement, while the electrical response was not affected. When compared with recordings in normal Krebs' solution, the average resting membrane potential was not altered. However, the membrane potential was more stable, with far less spike-shaped potentials. The spike-shaped potential amplitude was larger, while the duration was decreased. Conclusions: Impairing the ability of tissue movement resulted in changes in the electrophysiological properties of detrusor smooth muscle cells. The results suggest that stretch has an effect on L-type Ca2+ channels

The variable outflow resistance catheter: a new method to measure bladder pressure noninvasively (Article)

2001-02-15T00:00:00Z

PURPOSE: In a previous study an external condom catheter was used to measure noninvasively bladder pressure during interruption of the flow rate. The pressure increase in the condom sometimes caused a sphincter contraction that made bladder pressure measurement unreliable. Therefore, we developed a new variable outflow resistance catheter to measure noninvasively bladder pressure without interrupting the flow rate. MATERIALS AND METHODS: The new catheter consists of an incontinence condom connected to a set of various outflow tubes and a pressure transducer. A remotely controlled pneumatic valve was fitted over each tube to interrupt flow through it. We measured isovolumetric pressure, maximum flow rate, and pressure and flow rates at various outflow resistances in 9 healthy male volunteers. RESULTS: We derived a mathematical equation to estimate isovolumetric pressure from the pressure and flow rate values measured at various outflow resistances. The difference in the estimated and truly measured mean isovolumetric pressures plus or minus standard deviation was 0 +/- 6 cm. water. CONCLUSIONS: The new variable outflow resistance catheter may be used to measure isovolumetric bladder pressure noninvasively without interrupting the flow rate. It has been previously shown that a combination of this pressure and a separately measured maximum flow rate may be used to diagnose bladder outlet obstruction noninvasively

Supramaximal stimuli do not evoke a maximal contraction in urinary bladder smooth muscle fibers (Article)

2001-01-01T00:00:00Z

BACKGROUND: Smooth muscle fibers can be stimulated with an electrical field, high potassium or carbachol. We studied the effect of combined, supramaximal stimulation on the isometric force and the maximum shortening velocity of the pig urinary bladder. MATERIALS AND METHODS: After determining the dose response curve of each stimulation type, we stimulated 8 fibers with cumulative addition of supramaximal stimuli. RESULTS: The isometric force elicited with either potassium, carbachol or electrical field stimulation alone was the same for each stimulus. After addition of a second or third different supramaximal stimulus, the force further increased to a value that was on average 40% higher. CONCLUSIONS: Carbachol, high potassium or electrical field stimulation work through different stimulation pathways. Maximum stimulation with one of the stimuli does not result in a maximum isometric force development and maximum shortening velocity.

Computerized assessment of detrusor instability in patients treated with sacral neuromodulation (Article)

2000-12-23T00:00:00Z

PURPOSE: We previously described an automatic procedure for diagnosing and grading detrusor instability using a cystometric study. In our current study we applied a modified version of the program in patients with urge incontinence treated with sacral neuromodulation to test its capacity to detect changes after therapeutic intervention and understand the mode of action of neuromodulation. MATERIALS AND METHODS: We analyzed cystometric studies before and after neuromodulation in 26 consecutive patients, including 22 women and 4 men, and evaluated parameter changes. We also assessed the relationship of instability parameters at baseline with symptomatic results, which were derived from voiding-incontinence diaries, in female patients to identify urodynamic prognosticators of success. RESULTS: The automatic procedure correctly diagnosed stability and instability in our patients in 51 of the 52 measurements considered. Neuromodulation had an average suppressive effect on the amplitude of unstable contractions. At baseline the amplitude of the maximum unstable contraction and mean active pressure during unstable episodes were significantly less in the 7 women who achieved stability than in the 15 who did not. However, no urodynamic parameters were identified that predicted the symptomatic outcome of treatment. CONCLUSIONS: Our algorithm accurately diagnoses and grades detrusor instability, and provides parameters with predictive value in regard to the probability that a bladder may or may not become stable with neuromodulation. However, the symptomatic result of this treatment option seems to depend on noncystometric factors

The role of intracellular and extracellular calcium in mechanical and intracellular electrical activity of human urinary bladder smooth muscle (Article)

2000-09-30T00:00:00Z

We studied the role of extracellular and intracellular Ca2+ in human detrusor smooth muscle contraction. Simultaneous recordings of mechanical and intracellular electrical activity were made in three different Ca2+ concentrations: normal Krebs' solution (100%), 10% of the standard Ca2+ concentration and a solution in which Ca2+ was omitted from the medium (0%). Spontaneous contractions and KCl or CCh induced contractions were studied. Ryanodine and caffeine were used to manipulate the intracellular Ca2+ stores. The present results show that only a very small amount of Ca2+ in the extracellular space is sufficient to support spontaneous and induced contractions. Spike-shaped potentials and long lasting depolarisations were recorded in all three solutions. However, the prevalence of long lasting depolarisations increased when the extracellular Ca2+ concentration was reduced. The amplitude of the spike-shaped potentials and long lasting depolarisations appeared to be negatively affected by diminishing the extracellular Ca2+ concentration. Additionally, the duration of the long lasting depolarisations was reduced in 0% Ca2+. The contraction upon KCl stimulation was primarily depending on the extracellular Ca2+. Upon muscarinic receptor stimulation, a combined activation of Ca2+ mobilisation from intracellular and extracellular stores may occur; the ratio of contribution of these two sources changes in accordance with the requirements of the conditions

Changes in bladder contractility and compliance due to urethral obstruction: a longitudinal followup of guinea pigs (Article)

2000-08-25T00:00:00Z

PURPOSE: We established the longitudinal changes in bladder contractility and compliance as a result of urethral obstruction using a guinea pig model. MATERIALS AND METHODS: Obstruction was induced in guinea pigs by a silver ring around the urethra. Urodynamic studies were performed longitudinally in individual animals. Bladder contractility and compliance were calculated from the measured bladder pressure and urine flow rate. RESULTS: Bladder contractility developed in distinct phases. It reached a maximum 200% increase after an average of 3.25 weeks concomitant with an almost 2-fold increase in urethral resistance, remained 150% to 200% increased during weeks 4 to 7 and then decreased to starting levels again, while urethral resistance remained almost 2-fold increased. Bladder compliance decreased by 80% during the first 3 weeks and continued to decrease to 5% of its original value after 10 to 11 weeks. CONCLUSIONS: Our data indicate that as a result of obstruction bladder function passes through a specific sequence of stages, including first a compensatory increase in contractility, then a stabilization phase and finally a decompensation state. In contrast bladder compliance shows a continuous decrease. The data suggest that for assessing how far a bladder has deteriorated due to obstruction a combination of functional and structural data may be warranted

Simultaneous recording of mechanical and intracellular electrical activity in human urinary bladder smooth muscle (Article)

2000-07-25T00:00:00Z

OBJECTIVE: To elucidate the role of the membrane potential in human detrusor smooth muscle contraction, by simultaneously recording mechanical and intracellular electrical activity in muscle strips. Materials and methods The agonists acetylcholine and carbachol were applied to induce a contraction on muscarinic receptor stimulation; to block the response, atropine was added to the bath. The Ca2+ necessary for activating the contractile machinery can be recruited via two pathways: release from intracellular stores or influx from the extracellular matrix. High potassium was applied to induce Ca2+ influx through voltage-sensitive Ca2+ channels. RESULTS: There were significant changes in the force when agonist, antagonist and high potassium was administered. However, there were significant changes in membrane potential only when KCl was applied to the bath and not with muscarinic agonist or antagonist application. Activity in the form of spike potentials did not change significantly on applying any of the test substances. CONCLUSION: The present results indicate that the Ca2+ mobilized on M3 receptor stimulation originates primarily from intracellular stores, with no systematic changes in membrane potential. Atropine only caused a relaxation in muscle previously contracted by M3-receptor agonist stimulation; it had no effect on relaxed muscle strips

Factors causing differences in voiding parameters between conventional and ambulatory urodynamics (Article)

2000-06-13T00:00:00Z

Voiding parameter values measured with ambulatory urodynamic monitoring (AM) are generally found to be different from those measured with conventional cystometry (CMG). The reason for this is unclear, but might be related to differences in the voided volume. To verify this hypothesis, we compared voidings from female patients at an initial bladder volume that was close to the modal volume (that is, the volume most often voided by the patient as derived from frequency/volume charts) with voidings at maximum cystometric capacity during a routine video urodynamic examination. A first group of 35 patients voided at the modal volume before they did at capacity. The order was reversed in a second group of 12 patients. The dependence of the voiding parameters on the voided volume and the order of the measurements were examined. It was found that the maximum flow rate depended significantly on the voided volume, but the associated detrusor pressure did not. Urethral resistance and bladder contraction strength were not volume dependent either. It was concluded that the differences between AM and CMG cannot be explained from possible differences in the voided volume

Non-invasive measurement of bladder pressure using an external catheter (Article)

1999-09-24T00:00:00Z

Previous studies showed that, on the basis of a combination of maximum flow rate and isovolumetric bladder pressure, objectively diagnosing infravesical obstruction is possible. In this study, we validated a newly developed external catheter to measure non-invasively this pressure, which avoids the risk of damaging or infecting the urethral and bladder wall as occurs with invasive urodynamics. To evaluate the external catheter, we simultaneously recorded the internal bladder pressure signal (measured invasively) and the external pressure signal (measured non-invasively) in 40 non-obstructed and obstructed patients. Additionally, we tested whether the external pressure depended on bladder volume in five healthy volunteers. The simultaneously measured internal bladder pressure and external pressure showed good agreement in the non-obstructed patients. There was less agreement in the obstructed group. Nevertheless, the external pressure in these patients was significantly higher than in the non-obstructed patients. The maximum external pressure depended significantly on the bladder volume in all volunteers. We concluded that isovolumetric bladder pressure can be measured non-invasively with the external catheter. In non-obstructed patients, this pressure accurately represents the internal bladder pressure. We think that it is possible to distinguish between obstructed patients and patients with a weak detrusor by combining the non-invasively measured isovolumetric bladder pressure with a separately measured maximum flow rate.

Authors' reply (Article)

1999-09-24T00:00:00Z

Towards a noninvasive urodynamic diagnosis of infravesical obstruction (Article)

1999-08-12T00:00:00Z

Repeat noninvasive bladder pressure measurements with an external catheter (Article)

1999-07-01T00:00:00Z

PURPOSE: Previously it has been shown that an objective diagnosis of infravesical obstruction can be made by combining the maximum flow rate and isovolumetric bladder pressure. We evaluate a noninvasive method to measure isovolumetric bladder pressure to help develop a noninvasive modality for diagnosing obstruction. MATERIALS AND METHODS: An external catheter consisting of an incontinence condom, tube and pressure transducer was used. Flow rate through the catheter was remotely interrupted to measure the bladder pressure in the condom. Two series of measurements were done in 11 healthy male volunteers. In the first series we determined whether voiding was affected after flow rate interruption. In the second series we analyzed repeat pressure measurements of 1 voiding to determine whether maximum isovolumetric pressure depended on bladder volume. RESULTS: Flow rate was unaffected after interruption for pressure measurement. Repeat measurements of isovolumetric bladder pressure demonstrated that the pressure depended significantly on bladder volume. Average maximum isovolumetric pressure was 12.2 kPa. at a bladder volume of 251 ml. CONCLUSIONS: As no inhibition of voiding was noted after a single pressure measurement, repeat noninvasive measurements can be made on voiding. With repeat measurements the dependence of isovolumetric bladder pressure on bladder volume can be considered to obtain a reliable estimate of pressure as a basis for a noninvasive diagnosis of obstruction.

Threshold for efferent bladder nerve firing in the rat (Article)

1999-01-01T00:00:00Z

In this study, the mechanism involved in the initiation of voiding was investigated. Bladder pressure and bladder and urethral nerve activity were recorded in the anesthetized rat. Bladder nerve activity was resolved into afferent and efferent activity by means of a theoretical model. The beginning of an active bladder contraction was defined as the onset of bladder efferent firing at a certain time (t0). From t0 onward, bladder efferent activity increased linearly during deltat seconds (rise time) to a maximum. The pressure at t0 was 1.0 +/- 0.4 kPa, the afferent nerve activity at t0 was 2.0 +/- 0.6 microV (53 +/- 15% of maximum total nerve activity), and deltat was 11 +/- 13 s. Between contractions the afferent activity at t0 was never exceeded. Urethral afferent nerve activity started at bladder pressures of 2.1 +/- 1.1 kPa. Therefore, we concluded that urethral afferent nerve activity does not play a role in the initiation of bladder contractions; voiding contractions presumably are initiated by bladder afferent nerve activity exceeding a certain threshold.

Diagnosis and grading of detrusor instability using a computerized algorithm (Article)

1998-05-01T00:00:00Z

PURPOSE: Detrusor instability and hyperreflexia are characterized by involuntary detrusor contractions in the filling phase of the voiding cycle. The diagnosis is made when urodynamic evaluation reveals such contractions. To compare patients and evaluate treatment a method is needed to quantify the degree of instability. We developed an instability parameter based on the area under the curve of involuntary detrusor contractions on conventional filling cystometry. MATERIALS AND METHODS: We developed an automatic method to calculate the area under the curve of involuntary detrusor contractions in conventional filling cystometry. Logistic regression was used to construct decision rules to differentiate stable from unstable bladders. These rules, derived from a group of 100 children, were applied to a second group of 77 who were independently assessed by 3 urodynamics experts. RESULTS: Typically 88% of the second group were correctly classified as stable or unstable by the automatic procedure. In the unstable subgroup there was poor correlation between the calculated instability parameter and the instability score assigned by the experts. Most likely this difference occurred because the experts based their opinion mainly on the amplitude of the highest unstable contraction and the percentage of filling time that instability was found. CONCLUSIONS: The proposed method of automatically grading detrusor instability based on the area under detrusor contractions differs from the intuitive method used by experts. Since no standard is available, it cannot be concluded which method is better. Our proposed method is objective and it results in a single physical value.

Neurophysiological modeling of voiding in rats: urethral nerve response to urethral pressure and flow (Article)

1998-01-01T00:00:00Z

In male urethan-anesthetized rats, activity was measured in nerves that run over the proximal urethra. The urethral nerve response to stepwise urethral perfusion could be described by a four-parameter model (fit error < 6%). At the onset of perfusion, the urethra was closed and the pressure increased with the infused volume. The nerve activity (NA) increased linearly with this inserted volume to a maximum (NAmax), which was proportional to the instantaneous pressure. The duration of this first episode (delta t) was inversely proportional to the perfusion rate. After infusion of a fixed volume, the urethra opened and the NA decreased with a time constant phi -1 (approximately 1.8 s) to an elevated level (NAlevel). NAlevel was linearly related to the steady-state pressure. Accordingly, sensors in the urethra are sensitive to pressure rather than to the perfusion rate. The parameters NAmax, NAlevel, and delta t showed very good reproducibility (SD approximately 19% of mean). The measured activity was most likely afferent and conducted to the major pelvic ganglion.

Standardization of terminology of lower urinary tract function: pressure-flow studies of voiding, urethral resistance, and urethral obstruction (Article)

1997-01-01T00:00:00Z

The 1988 version of the collated reports on standardisation of terminology, which appeared in Neurourology and Urodynamics, vol. 7, pp. 403–427, contains material relevant to pressure flow studies in many different sections. This report is a revision and expansion of Sections 4.2 and 4.3 and parts of Sections 6.2 and 7 of the 1988 report. It contains a recommendation for a provisional standard method for defining obstruction on the basis of pressure-flow data. 2. Evaluation of Micturition 2.1. Pressure-Flow Studies At present, the best method of analysing voiding function quantitatively is the pressure-flow study of micturition, with simultaneous recording of abdominal, intravesical and detrusor pressures and flow rate (Fig. A.1.6.1). Direct inspection of the raw pressure and flow data before, during and at the end of micturition is essential, because it allows artefacts and untrustworthy data to be recognised and eliminated. More detailed analyses of pressure-flow relationships, described below, are advisable to aid diagnosis and to quantify data for research studies. The flow pattern in a pressure-flow study should be representative of free flow studies in the same patient. It is important to eliminate artefacts and unrepresentative studies before applying more detailed analyses. Pressure-flow studies contain information about the behaviour of the urethra and the behaviour of the detrusor.

Neurogenic modulation of urethral resistance in the guinea pig (Article)

1996-01-01T00:00:00Z

Purpose: The resistance offered to urinary flow by the urethra is one of the factors determining the course of micturition. It was the aim of the present work to study the dependence of urethral resistance on the degree of relaxation of the urethra. Materials and Methods: Experiments were done in the guinea pig. Ten animals were used. In 5 animals saline was forced through the (unrelaxed) urethra at imposed flow rates in the range of 1.1 to 43.0 ml. per minute while the urethral pressure was measured. Second degree polynomials were fitted to the pressure/flow data. In the other 5 animals micturition contractions were evoked and pressure/flow plots were derived from the measured signals. A straight line was fitted to the lowest pressure values at each flow rate in these plots. These pressure values represent the most relaxed state of the urethra in these voidings. Results: The pressures measured in the unrelaxed urethra were much higher than the pressures measured during voiding in the same flow rate range, but the intercepts of the mathematical equations fitted to the pressure/flow data on the pressure axis were not significantly different in the 2 groups. Conclusions: The unrelaxed urethra has a much "steeper" pressure/flow characteristic than the relaxed urethra. However, the urethral closing pressure, that is, the intercept of the pressure/flow characteristic on the pressure axis, does not depend on the state of relaxation of the urethra.

Linearisation of a urinary flow transducer (Article)

1995-11-01T00:00:00Z

A comparative study of voiding in rat and guinea pig: simultaneous measurement of flow rate and pressure (Article)

1995-07-01T00:00:00Z

In this study, the voiding phase of the micturition cycle in the anesthetized rat and guinea pig is analyzed. In both animals, voiding is characterized by an increase in intravesical pressure and then a decrease, which is accompanied by flow through the urethra and emission of urine. An ultrasonic flow probe was used in both species to measure the flow rate in relation to the intravesical pressure. In the (male) rat, so-called high-frequency oscillations are superimposed on the decreasing bladder pressure. These oscillations do not occur in the guinea pig. It is concluded that the high-frequency oscillations are caused by intermittent flow and not by variations in the bladder contraction. The intermittent flow most likely is caused by the relaxation and contraction of the external urethral sphincter and may have a function in territory marking. In our view, it is not likely that the oscillations enhance bladder emptying, as has been suggested in the literature.

Analysis of pressure-flow data in terms of computer-derived urethral resistance parameters (Article)

1995-01-01T00:00:00Z

The simultaneous measurement of detrusor pressure and flow rate during voiding is at present the only way to measure or grade infravesical obstruction objectively. Numerous methods have been introduced to analyze the resulting data. These methods differ in aim (measurement of urethral resistance and/or diagnosis of obstruction), method (manual versus computerized data processing), theory or model used, and resolution (continuously variable parameters or a limited number of classes, the so-called monogram). In this paper, some aspects of these fundamental differences are discussed and illustrated. Subsequently, the properties and clinical performance of two computer-based methods for deriving continuous urethral resistance parameters are treated.

Neurogenic modulation of micturition: the relation between stimulation intensity and the maximum shortening velocity of the guinea pig detrusor muscle (Article)

1995-01-01T00:00:00Z

The course of micturition depends on bladder contractility and urethral resistance. The former is determined by geometrical, muscular and neurogenic factors. The muscular aspects of bladder contractility can be characterized by the parameters Pisv, the isovolumetric detrusor pressure, and vmax, the maximum (unloaded) shortening velocity of the detrusor muscle. The neurogenic control system of the urinary tract modulates bladder contractility, which might effectively change the values of Pisv and vmax. These parameters also depend on the instantaneous bladder volume. In previous work the dependence of Pisv on the intensity of stimulation and bladder volume was measured in guinea pig bladders in vivo and in vitro. In the present work vmax was derived in 5 guinea pig bladder in vitro, using electrical stimulation and the stop-flow technique. This technique implies that pressure values measured at a certain shortening velocity of the bladder circumference and in an isovolumetric contraction at the same volume are used to derive vmax mathematically from the Hill equation. vmax was independent of the bladder volume in the range of 0.6 to 6.1 ml., but it was significantly different for the two intensities of stimulation used. Therefore, it is concluded that the maximum shortening velocity of the guinea pig detrusor muscle depends on the intensity of stimulation. During submaximal stimulation the detrusor not only generates lower pressures, it also contracts more slowly. A possible explanation for this phenomenon is that the bladder is not uniformly stimulated. The isovolumetric pressure measured in the stop-flow test was compared with the isovolumetric pressure measured at the same bladder volume some minutes later. It was observed that shortening had a depressant effect of approximately 33% on the isovolumetric pressure. This implies that the clinically employed stop-flow test might underestimate detrusor contraction strength.

Dependence of male voiding efficiency on age, bladder contractility and urethral resistance: development of a voiding efficiency nomogram (Article)

1995-01-01T00:00:00Z

The influence of age, urethral resistance and bladder contractility on voiding efficiency was evaluated by pressure-flow studies in 138 men of a mean age of 60 years (range 18 to 86). From these studies the urethral resistance parameter was calculated and the maximum bladder contraction strength was determined. Premature fading of the bladder contraction was quantified by a bladder contraction strength decay factor. Voiding efficiency was expressed by the parameter of post-void residual urine volume as a percentage of the initial bladder volume. Multiple regression analysis showed that voiding efficiency depended significantly in descending order of importance on urethral resistance, maximum bladder contraction strength and bladder contraction strength decay factor. Patient age was not an independent factor. Maximum bladder contraction strength and bladder contraction strength decay factor were not correlated, suggesting that maximum bladder contraction strength and its decay constitute different properties of bladder contractile function. A voiding efficiency nomogram is proposed, making use of the values for maximum bladder contraction strength and urethral resistance in individual patients. Such a nomogram may have predictive value for the occurrence of acute retention but it must be tested prospectively.

Reasons for the weak correlation between prostate volume and urethral resistance parameters in patients with prostatism (Article)

1995-01-01T00:00:00Z

In an attempt to increase our understanding of the clinical syndrome of benign prostatic hyperplasia (BPH) an analysis was made of the association between prostate volume as measured by transrectal ultrasound and several reported urodynamically determined urethral resistance parameters. Two types of obstruction can be recognized on the basis of urodynamic data: a compressive type characterized by a high urethral opening pressure and a prolonged isovolumetric contraction phase before urine flow can start, and a constrictive type characterized by a normal opening pressure and an increased slope of the urethral resistance relation. A combination of both types is often seen in BPH. In our study, parameters that selectively quantify compression correlate weakly to moderately with prostate volume, whereas parameters that mainly quantify constriction do not correlate at all with prostate volume. Parameters that combine a measure for compression and constriction correlate less well with prostate volume than parameters that mainly quantify compression. The variation in prostate volume was found to determine the variation in urethral resistance by 15% or less depending on the parameter used, which implies that the different pathophysiological mechanisms that can increase urethral resistance in the complex process of clinical BPH are mainly determined by factors other than the volume of the prostate. Thus, despite the lack of correlation between prostate volume and urethral resistance, pressure-flow studies and the determination of urethral resistance parameters provide a valuable contribution to the understanding of the pathophysiology of voiding dysfunction in men with symptoms of prostatism.

Nonuniform sampling of urodynamic signals: a comparison of different methods (Article)

1994-08-12T00:00:00Z

Several different techniques for urodynamic signal compression have been proposed in the last few years. Using these techniques it is possible to reduce the requirements for digital storage or transmission. There are a number of applications where it is essential to use such techniques in diagnostic and ambulatory urodynamics. The purpose of this study is to compare different techniques of urodynamic data compression. The so-called FAN, voltage triggered, two point projection and second difference methods. The comparison between the methods is based on 65 pressure, 46 uroflow and 18 surface electromyogram signals. The reduction ratio achieved for different allowable errors between the original and compressed signals is calculated and compared for the different techniques. Results show that it is possible to store urodynamic signals accurately at a low sampling rate, where FAN and voltage triggered methods seem to be superior to the rest.

Transrectal ultrasound of the prostatic urethra related to urodynamically assessed urethral resistance. A pilot study (Article)

1994-08-12T00:00:00Z

In this pilot study on 17 men who underwent urodynamic investigation for various dysuric complaints, real-time transrectal ultrasonography (TRUS) was performed. From the images anatomical parameters were identified that correlated with obstructive urodynamic findings and urethral resistance parameters based on pressure-flow analysis. This study gives support for further clinical investigations to determine the value of TRUS for male patients with dysuric disorders. It also illustrates the anatomical basis of prostatic obstruction as quantified by objective urodynamic parameters.

Photolysis of caged calcium using a low-cost flash unit: efficacy analysis with a calcium selective electrode (Article)

1994-01-01T00:00:00Z

Photolysis of caged calcium (Nitr5, Calbiochem) can be used to study calcium dependent processes such as excitation-contraction coupling and muscular mechanics. Expensive high energy light sources are routinely used for UV light exposure, but this study describes an alternative low cost xenon flash unit constructed in our laboratory. A 300 J short arc xenon flash lamp (Heimann) was mounted in an elliptical reflector and driven by a modified Metz 60 CT 4 photoflash unit up to 240 J input energy and 4 ms flash duration. A 20 microliters cuvette containing a test solution was placed in a complementary elliptical reflector. An ion selective calcium electrode was used to measure the free calcium concentration [Ca2+] before and after flash in test solutions containing 1.00 mM Nitr5 in combination with different added [Ca2+]s. Using this technique we estimated that 1 flash on 1.00 mM Nitr5 increased the free [Ca2+] from 10(-7) to 1.1 x 10(-5) M. When the added [Ca2+] was less than 2.3 x 10(-4) M, the used Nitr5 behaved as a strong calcium chelator because 23% of it was unloaded with calcium. It is concluded that a physiologically relevant change in free [Ca2+] can be evoked by photolysis of Nitr5 using a low cost (approximately $1500) xenon flash unit, and that ion selective Ca electrodes can be adequately used to monitor the resulting changes in [Ca2+].

Automated evaluation of urethral obstruction (Article)

1993-08-01T00:00:00Z

The measurement of detrusor pressure and flow rate during voiding is the only way to objectively measure or grade infravesical obstruction. The resulting data cannot be interpreted easily. Manual as well as automatic methods have been introduced to derive one or several factors or parameters to quantify urethral resistance. A number of these methods are described in this overview. Since automatic methods involving computers guarantee uniform, unbiased, and objective processing of data, besides enabling the use of (statistical) methods that take into account more than one or two of the measured pressure and flow rate values, emphasis is on these methods. Some clinical results obtained with such automatic methods are discussed to illustrate the clinical value and possible impact on diagnosis and evaluation of treatment of lower urinary tract disorders.

A method for isolating smooth muscle cells from pig urinary bladder with low concentrations of collagenase and papain: the relation between calcium concentration and isolated cell length. (Article)

1993-01-01T00:00:00Z

The present study describes a method for isolating single smooth muscle cells from pig urinary bladder using a continuous resuspension device. Low concentrations of collagenase and papain were sufficient to obtain a high yield of viable smooth muscle cells, which remained viable for about 3-4 h as tested with fluorescein diacetate. Addition of fetal calf serum increased the lifespan of the isolated cells and the percentage of contractile smooth muscle cells, but caused spontaneous shortening of the cells. The length and volume of the isolated smooth muscle cells depended on the calcium concentration used in the isolation buffer solution. The isolated muscle cells were apparently relaxed if a calcium concentration less than 1.0 mmol/l was used in the isolation medium. In higher calcium concentrations the isolated cells were significantly shorter, probably as a result of a contraction caused by mechanical stimulation of the cells during the isolation procedure.

Cell length measurements in longitudinal smooth muscle strips of the pig urinary bladder (Article)

1993-01-01T00:00:00Z

In this study the length of smooth muscle cells in muscle bundles of pig urinary bladder wall was determined after dissection in Tyrode buffers with different calcium concentrations ([Ca2+]). Previous studies have shown that the length of isolated smooth muscle cells decreases with an increase in [Ca2+] in the buffer. Unlike the results in isolated cells, no significant differences in length were found between cells in strips subjected to different [Ca2+]. Cells in bundles dissected from filled bladders were significantly larger than those dissected from emptied bladders. Cells in strips from emptied bladders dissected in 1.8 mM Ca(2+)-Tyrode buffer were shorter than those obtained in Ca(2+)-free buffer. From the measurements it was concluded that: (1) Cell length in intact tissue is directly related to tissue length; series elastic structures external to the cells do not allow significant shortening of the cells. (2) Passive parallel elasticity outside the cells accounts for passive shortening when bladders are emptied manually. (3) Cell length is not related to empty bladder weight. (4) A positive relation exists between empty bladder weight and bladder capacity.

Effect of partial urethral obstruction on force development of the guinea pig bladder (Article)

1993-01-01T00:00:00Z

We created gradual partial urethral obstruction in 20 guinea pigs using silver jeweler's jump rings. After 4 or 8 weeks obstruction all animals underwent cystometry and were assigned to one of five urodynamic categories: normal, high pressure voiding, unstable, low compliance, or decompensated. After sacrifice, the contractile responses of bladder strips to electrical field stimulation of intramural nerves, direct electrical muscle stimulation, 0.1 mM carbachol, and high K+ solution were sampled by computer for phase plot analysis. Following 8 weeks obstruction, the value of the phase plot parameter Fiso, indicative of the number of contractile muscle units, was reduced to 60% of the control response to nerve stimulation (P < 0.05) and to 77% of the control response to carbachol stimulation (P < 0.05). Parameter C, the slope of the phase plot (indicative of unit recruitment during force development), was unchanged for all forms of stimulation. Although in the latter case not statistically significant, obstruction affected responses to nerve and muscle stimulation similarly suggesting that muscle change may possibly be a common denominator of dysfunction. In view of the reduction in Fiso and the increase in bladder weight, instability may represent a more advanced form of dysfunction due to obstruction than high pressure voiding.

The force recovery following repeated quick releases applied to pig urinary bladder smooth muscle (Article)

1991-02-01T00:00:00Z

A method for measuring several quick-releases during one contraction of a pig urinary bladder smooth muscle preparation was developed. The force recovery following quick release in this muscle type was studied by fitting a multiexponential model to 926 responses measured during the first 700 ms after release, both in the stimulated and in the unstimulated muscle. It was concluded that the force recovery in this observation window was biexponential and that the two time constants result from two fundamentally different processes. The slower time constant in the order of 0.45 s was ascribed to crossbridge cycling, and this hypothesis was supported by the considerable dependence of the amplitude associated with this time constant on the stimulus condition of the muscle. The faster time constant in the order of 0.032 s was found to be largely independent of the degree of stimulation of the muscle and was ascribed to a passive, viscoelastic process.

Mechanical properties of mammalian single smooth muscle cells. III. Passive properties of pig detrusor and human a terme uterus cells. (Article)

1990-10-01T00:00:00Z

Cells isolated from pig urinary bladders and pregnant full term human uteruses were attached longitudinally between a microforce transducer and a length displacement apparatus. Cells were stretched by applying a series of ramp-like length changes of 0.2 s duration and 10.0 microns amplitude at intervals of 15 min. Passive forces upon straining were as high as 70-100 microNs. Following these peak forces stress relaxation occurred, levelling off approximately 50% of the maximum peak force. The maximum elastic modulus estimated for single cells was found to be at least a tenfold higher than was previously estimated from intact bladder strips. The relation between the increase in length and the increase in initial force increment was found to be approximately linear. An exponential equation was fitted to a selected number of stress relaxation curves. Relaxation curves of bladder cells show a clearly different time course as compared to bladder tissue strips, suggesting that a significant amount of relaxation in strips has to be contributed to the connective tissue components or to structural changes in these strips.

Mechanical properties of mammalian single smooth muscle cells. II. Evaluation of a modified technique for attachment of cells to the measurement apparatus (Article)

1990-08-01T00:00:00Z

A method is described for attaching isolated single smooth muscle cells to an apparatus designed for measuring the longitudinal forces developed passively and actively by the cell upon straining, electrical or pharmacological stimulation. Primary attachment of the cell is based on its natural negative surface charge in combination with a positive surface charge on the micro-tools used for attaching. Definite attachment is obtained by a knotting technique. Results show that this method of attachment is reliable and strong enough to withhold forces exceeding those necessary to break or tear the cell. Although this method allows relatively short cells to be attached (L greater than 80 microns). alternative methods e.g. glueing, are necessary to attach the shortest smooth muscle cells.

Mechanical properties of mammalian single smooth muscle cells. I. A low cost large range microforce transducer. (Article)

1990-08-01T00:00:00Z

A transducer has been developed for measuring the minute forces generated during isometric contractions (1.0-10.0 microN) of single smooth muscle cells from the pig urinary bladder and the human uterus. In addition to its high sensitivity, resolution and stability (100 mV microN-1, and less than 0.1 microN and less than 2.0 microN h-1), the transducer features a very wide range (100-140 microN) with good linearity, enabling measurement of contractions as well as passive force-length characteristics within one uninterrupted measurement session. Since the transducer features an independent and interchangeable force to displacement conversion system, different force ranges can be realized by inserting force conversion systems with different compliances.

Estimation of the maximum contraction velocity of the urinary bladder from pressure and flow throughout micturition. (Article)

1990-01-01T00:00:00Z

The contractility of the urinary bladder can be adequately described in terms of the parameters P0 (isometric pressure) and Vmax (maximum contraction velocity). In about 12% of urodynamic evaluations of patients these clinically relevant parameters can be calculated from pressure and flow rate as measured during micturition. A method was developed of estimating Vmax for any micturition from these signals. The properties of this estimated contractility parameter were clinically tested and are discussed.

Efficient storage of urodynamic signals by computer: application of FAN adaptive sampling (Article)

1989-01-01T00:00:00Z

Digital storage of urodynamic signals such as detrusor pressure and flowrate at a sufficiently high sampling rate (10 samples per second) to allow subsequent analysis requires considerable computer memory. A procedure for compressing these data by deleting redundant samples (the fan method of adaptive sampling) was tested. The method allows a flexible adaptation to specific hardware and a compromise between storage requirements and accuracy. In this study the number of samples required for adequate reconstruction of the detrusor pressure signal could be varied from 80% to 4% of the original number of samples by varying the average difference between reconstructed and original signal from 0.01 to 2 cm H2O. Fast components of the measurements (for example cough peaks) which were lost if a lower sampling rate or averaging was used to obtain equally low storage requirements were unaffected by this compression technique.

The length dependence of the series elasticity of pig bladder smooth muscle (Article)

1988-12-01T00:00:00Z

Strips of urinary bladder smooth muscle were subjected to a series of quick release measurements. Each measurement consisted of several releases and resets to the original length, made during one contraction. The complete length-force characteristic of series elasticity was quantified by estimating H, the amplitude of quick release necessary to reduce the active force to exactly zero, and Db, a measure for the deviation of the characteristic from a straight line. By measuring a series of contractions at increasing stretched strip lengths, the length dependence of these parameters was studied. It was found that H depends linearly on stretched strip length. On average H/length amounted to 0.04. Db decreased when strips were stretched, i.e. a straight line was more closely approximated. Both parameter dependencies support the concept of two separate elastic mechanisms, a linear true passive elasticity in series with a non-linear elasticity in the cross-bridges. For the latter, H amounts to 3.8% of the initial strip length.

Low-cost computer-controlled asynchronous-video cross-hair device (Article)

1987-07-01T00:00:00Z

Isolation and individual electrical stimulation of single smooth-muscle cells from the urinary bladder of the pig (Article)

1987-04-01T00:00:00Z

In contrast to striated muscle, measurements on strips of smooth muscle cannot be uniquely interpreted in terms of an array of contractile units. Therefore scaling down to the single-cell level is necessary to gain detailed understanding of the contractile process in this type of muscle. The present study describes the development of a method for isolating contractile single smooth muscle cells from pig urinary bladders. Contractile responses evoked by individual electrical stimulation were used as a measure of cell quality during development of the method. Responses were evaluated by measuring latency, contraction and relaxation times, as indicated by visible length changes, and stored on-line in a computer. Initial length, relative shortening and shortening speed were determined by measuring cell lengths in previously timed still video frames using a computer-controlled crosshair device. Increase of stimulus pulse duration resulted in improved responses, indicating that the observed shortening represented a physiological contractile response. Ultimately this method of evaluation was applied to two sets of cell preparations obtained by two different methods, one using only collagenase digestion, the other using mechanical manipulation as well. Both sets showed two main patterns of response to electrical stimulation: a pattern of contraction upon stimulation followed by enhanced contraction when stimulation was switched off (CK), and a pattern of contraction upon stimulation followed by relaxation when the stimulus was switched off (CR). The set of preparations containing the highest percentage of CR cells was found to be superior (i.e. greater initial length, shorter latency and contraction times, increased shortening and higher shortening speed). The method of isolation used for this set gives a high yield of contractile cells available for experimental use over a long span of time.

Clinical comparison of bladder contractility parameters calculated from isometric contractions and pressure-flow studies (Article)

1987-01-01T00:00:00Z

Parameters describing the contractility of the urinary bladder can be calculated from both isometric contractions and pressure-flow studies. The first method has the advantage of making very little demand either on the patient or on the urodynamicist, and the disadvantage of yielding a parameter that is not clearly related to muscle physiology. The second method demands more from both patient and experimenter but yields straightforward parameters. For a group of 86 patients with mixed pathologic findings, a correlation between the two types of parameters was demonstrated, showing that both methods test, at least partly, the same mechanism.

Urinary bladder function and its control in healthy females (Article)

1986-08-01T00:00:00Z

An Evaluation of Contractility Parameters Determined from Isometric Contractions and Micturition Studies (Article)

1986-01-01T00:00:00Z

In a group of 110 patients of mixed pathology 218 micturitions were investigated. Using an on-line computer, two contractility parameters were calculated: the parameter U/l, which is derived from the isometric pressure rise in the detrusor before micturition actually started, and the parameter wmax, which is derived from flow and pressure during micturition. It was found that neither of the parameters conforms to the definition of an ideal contractility parameter. Both parameters are subject to the influence of the urethral resistance or the degree of neurogenic stimulation of the bladder, and both measure to some degree the actual performance of the detrusor during a given micturition instead of its myogenic properties. Nevertheless, by dividing patients into groups according to these two measured values, it was shown that clinically relevant types of detrusor behaviour can be distinguished.

Electrical stimulation of smooth muscle strips from the urinary bladder of the pig (Article)

1985-01-01T00:00:00Z

Strips of smooth muscle from pig urinary bladders were electrically stimulated to contract. Stimulation parameters and conditions were optimized so as to obtain a maximum number of isometric contractions with maximal force. It was found that the contractions could be described mathematically by a simple model. In the model there is a constant probability for cells to pass from the non-contractile to the contractile state during stimulation; this leads to a linearly decreasing phase plot (a plot of the rate of rise of a variable as a function of the variable) for the force. 'Activation' of the cells is described by a physical step function. Isometric contractions were thus characterized by a set of three parameters: U, the time derivative of the force, extrapolated to zero force, Fiso the value of the isometric force which is approached asymptotically after infinitely long periods of stimulation and t1, the activation time. The sensitivity of these three parameters to variation of the stimulus parameters was investigated. It was found that the parameter U was consistently correlated with the stimulus parameters, suggesting that this parameter can be used to describe the effectiveness of electrical stimulation of such strips.

In vitro comparison of isometric and stop-test contractility parameters for the urinary bladder (Article)

1985-01-01T00:00:00Z

Contractility parameters in the urinary bladder can be calculated from isometric contractions (no extra patient load as compared to routine cystometry) or from stop-tests (more accurate, simpler analysis). A stop-test involves a voluntarily interrupted micturition with pressure and flow measurement. In a series of measurements in vitro on pig urinary bladder strips, parameters of the first type, obtained either by analyzing isometric contractions in terms of the Hill model, or by making phase plots, were compared to parameters of the second type. A good correlation was found. Th parameter correlating best with the maximal contraction velocity of the bladder, normalized for differences in initial muscle length, as obtained from stop-test, is the isometric contraction force, which can be obtained from an isometric contraction by either of the two analysis techniques. Clinically, making phase plots seems more promising than analyzing contractions in terms of the Hill model.

A computer program for on-line measurement, storage, analysis and retrieval of urodynamic data (Article)

1984-04-01T00:00:00Z

A computer program is presented which allows for direct connection of a minicomputer to a urodynamic set-up. The program stores measured pressure and flow data in a random access disc file with minimal intervention of the urodynamicist, and enables the direct application of a number of methods of analysis to the data. The program is modular, and other analysis methods are easily added. Results of analyses are stored in the same disc file, and both results and measured data can be quickly and easily retrieved. The program is written in FORTRAN; hardware-dependent functions (analog input, graphics display, and random access disc storage) are implemented in subroutines (partly assembler) which can easily be replaced.

Bolus propagation in pig ureter in vitro (Article)

1984-02-01T00:00:00Z

Pig ureters were made to propagate injected fluid boluses by electrical stimulation in vitro. The propagation velocity was determined from EMG measurements made at several points along the ureter. It was found that this velocity varied both along the ureter and as a function of time, and that it was related to the contraction pressure but not to the bolus size.

Analogue data collection via a telephone line: a microprocessor-based remote-controlled data-acquisition system. (Article)

1983-03-01T00:00:00Z

Series-elastic properties of strips of smooth muscle from pig urinary bladder (Article)

1982-09-01T00:00:00Z

Dependence of the viscoelastic response of the urinary bladder wall on strain rate (Article)

1981-05-01T00:00:00Z

Active mechanical properties of the smooth muscle of the urinary bladder (Article)

1979-05-01T00:00:00Z

Passive properties of the urinary bladder in the collection phase (Article)

1978-09-01T00:00:00Z

Constant-step approximation of multi-exponential signals using a least-squares criterion (Article)

1977-07-01T00:00:00Z

A short note on the performance of two computer programs for the estimation of the parameters of a multi-exponential model (Article)

1977-07-01T00:00:00Z

A Systems Approach to the Passive Properties of the Urinary Bladder in the Collection Phase (Doctoral Thesis)

1977-02-02T00:00:00Z

Urology is that branch of medicine which is concerned with the treatment of diseases of the urinary tract in men and women and of the reproductive tract in men (Rous, 1973). It will be clear that in urology, physical properties as flow, pressure, volume, and their relations are very important. A more or less separate discipline has therefore arisen which is called "urodynamics". Urodynamics concerns the knowledge gathered by the study of the physical events during transport of urine from the kidneys to the outside world. A description of urodynamical research is given by Melchior (1975). From the description it can be seen that urodynamics is a research field which demands interdisciplinary teamwork. Therefore, and since the actual structure of the urinary system is very complicated like that of all physiological systems, it is a very suitable field for a systems approach. The first aim in such an approach must be to describe quantitatively and in physical terms the properties of the urinary tract or parts of it. This thesis reports the results of such an approach to the passive properties of the urinary bladder in the collection phase.

Step-wise cystometry of urinary bladder. New dynamic procedure to investigate viscoelastic behavior (Article)

1973-09-01T00:00:00Z