Search

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

Purpose: We tested the hypothesis that the previously described penile urethral compression release (PCR) maneuver provides a valid diagnosis of bladder outlet obstruction (BOO) using automated rather than manual penile compression by controlled inflation of a penile cuff. We also investigated urodynamic events underlying generation of the PCR index., Materials and Methods: A total of 150 subjects attending for pressure flow studies were studied using conventional and noninvasive cystometry. Patients were classified into urodynamic diagnostic groups using standard invasive studies. The PCR index was calculated for each individual from noninvasive penile cuff data and the results were summarized for each group. ROC analysis of the PCR index was performed to define an optimum threshold for BOO diagnosis. Simultaneous invasive and noninvasive data were used to define the relationship between the PCR index, bladder contractility and the maximum flow rate., Results: The mean PCR index +/- SD was significantly higher in the BOO group compared to the normal cystometry group (215% +/- 84% vs 93% +/- 39, p <0.01). ROC analysis showed that a PCR index of greater than 160% diagnosed BOO with 78% sensitivity, 84% specificity and a positive predictive value of 69%. There was a strong positive correlation between the PCR index and isovolumetric detrusor pressure, which is a measure of bladder contractility (r = 0.44, p <0.01)., Conclusions: The results of this study suggest that the PCR index combines valid estimates of bladder contractility and the maximum flow rate, and it represents a clinically useful, noninvasive urodynamic parameter for the diagnosis of BOO.

Purpose: As part of developing a noninvasive method to measure bladder pressure using an inflatable penile cuff, we tested the hypothesis that detrusor contraction is maintained without inhibition during the test., Materials and Methods: Five healthy volunteers and 26 male patients with lower urinary tract symptoms underwent interruption of established urine flow by controlled inflation of a cuff placed around the penis with simultaneous invasive bladder pressure monitoring. After interruption of flow the cuff was rapidly deflated and voiding was allowed to resume. The bladder pressure was recorded before, during and after interruption of flow by cuff inflation., Results: During flow interruption an isovolumetric increase in detrusor pressure was observed. When the cuff was deflated the detrusor pressure quickly returned to preinflation values and urine flow immediately resumed. Intra-abdominal pressure did not change during the cuff inflation cycle., Conclusions: Mechanical interruption of urine flow by controlled inflation of a penile cuff during voiding does not inhibit detrusor contraction. This finding further validates our noninvasive technique of bladder pressure measurement and supports ongoing studies into its clinical usefulness.

Purpose: A noninvasive test providing reliable objective quantification of bladder pressure during the voiding cycle would make an important contribution to the management of lower urinary tract symptoms. We developed a new noninvasive test to measure bladder pressure in males based on controlled inflation of a penile cuff during voiding. We compared the new technique with simultaneous invasive bladder pressure measurement., Materials and Methods: We evaluated 7 volunteers and 32 patients. A conventional pressure flow study was performed first. The bladder was refilled, a penile cuff was fitted and after voiding commenced the cuff was inflated in steps of 10 cm. water every 0.75 seconds until urine flow was interrupted. The cuff was rapidly deflated, allowing flow to resume, and the cycle was repeated until the end of voiding. The flow rate was graphed against cuff pressure for each interruption cycle to determine the pressure at which flow was interrupted. This pressure was compared with simultaneous invasive isovolumetric bladder pressure., Results: Invasive and noninvasive pressure measurements agreed well. Average cuff pressure at interruption of flow exceeded mean simultaneous isovolumetric bladder pressure plus or minus standard deviation by 14.5 +/- 14.0 cm. water., Conclusions: The new method provides noninvasive quantitative information on voiding bladder pressure in males. Further study is required to assess whether the technique can contribute to the management of lower urinary tract symptoms.

Purpose: We developed a noninvasive method to measure voiding bladder pressure by inflating a penile cuff to interrupt flow. We tested the underlying assumption that cuff pressure is transmitted to the penile urethra., Materials and Methods: In 35 men we simultaneously recorded penile cuff and urethral pressure during 2 experimental protocols for 6 cuffs of various widths and manufactures. Initially a urethral pressure transducer was placed at the mid point of the cuff and urethral pressure was continuously recorded during cuff inflation. In experiment 2 cuff pressure was set at 120 cm. water and the urethral pressure profile was measured by withdrawing the urethral transducer through the cuff width., Results: There was excellent agreement of cuff with urethral pressure over the range of 0 to 200 cm. water for cuffs 37 to 54 mm. wide. Narrower cuffs showed wider variation with less efficient transmission of cuff pressure to the urethral lumen. Similarly maximum pressure in the urethral pressure profile showed best agreement for cuffs 38 and 46 mm. wide. Wider cuffs produced higher and narrower cuffs produced lower transmitted pressure within the urethra. Cuff performance was also related to penile size. Results had good within-subject repeatability., Conclusions: We demonstrated that pressure transmission from cuff to urethra is optimal at a cuff width of 40 to 50 mm. and recommended this width for other investigations of noninvasive bladder pressure measurement.

Upper tract dilatation is an important complication of neurogenic bladder dysfunction. Risk factors include incomplete bladder emptying with large residual volumes of urine and high tonic increases in bladder pressures during artificial filling. However, on natural bladder filling many of these patients do not have high tonic increases in detrusor pressures. We compared conventional urodynamic studies with ambulatory monitoring during natural bladder filling in 66 patients with low compliance neurogenic bladder dysfunction. There were marked differences in the tonic increase in bladder pressure during filling and in compliance during artificial bladder filling compared with ambulatory monitoring. Faster filling rates during artificial filling resulted in greater end filling pressures and lower compliance but the lowest increases in bladder pressure were found during ambulatory monitoring with natural bladder filling. During natural bladder filling significantly more patients had phasic changes in detrusor pressure; a high intensity of phasic activity during ambulatory monitoring correlated with high end filling pressures during artificial bladder filling. Upper tract dilatation was associated with large volumes of residual urine, high resting bladder pressures and low bladder compliance on filling at 100 ml. per minute. However, upper tract dilatation was most strongly associated with high intensity phasic pressure activity during natural bladder filling in combination with high residual urine volumes and high resting bladder pressures. On multivariate statistical analysis the intensity of phasic pressure activity during ambulatory monitoring was the best discriminator between patients with dilated and normal upper tracts. Our study has highlighted important differences in the results obtained by artificial filling cystometry and ambulatory monitoring during natural bladder filling. In particular, high increases in pressure did not occur during natural bladder filling, apparently being replaced by phasic activity. Within this group of patients who had the high risk factor of low bladder compliance measured during artificial bladder filling, a combination of greater residual urine volumes, greater resting pressures and greater phasic activity during natural bladder filling was found in patients with upper tract dilatation.

A total of 20 men awaiting elective prostatectomy for bladder outflow obstruction underwent conventional medium filling cystometry and ambulatory monitoring of bladder pressures during natural bladder filling. Total bladder capacity was similar during both tests (medium filling cystometry 256 +/- 138 ml. and ambulatory monitoring 248 +/- 120 ml., p not significant) as was the voided volume (medium filling cystometry 180 +/- 100 ml. and ambulatory monitoring 179 +/- 88 ml., p not significant). However, the peak urinary flow rate at the end of medium filling cystometry (4 +/- 6 ml. per second) was significantly lower than during ambulatory monitoring (9 +/- 4 ml. per second, p less than 0.05). The bladder contraction pressure during medium filling cystometry (79 +/- 44 cm. water) was significantly lower than during ambulatory monitoring (107 +/- 39 cm. water, p less than 0.005). Bladder pressures during voiding recorded after natural filling were significantly greater than after artificial filling. This finding may have significant implications for the use of conventional cystometry to study conditions such as outflow obstruction.

We have developed a system to perform fully ambulatory monitoring studies of the bladder. Bladder and rectal pressures are recorded during natural filling of the bladder for up to 6 hours. This system has been evaluated in 19 studies performed on 15 patients. The mean duration of the studies was 3 hours 51 minutes (standard deviation +/- 1 hour 3 minutes) and the mean number of voids per patient was 3.8 +/- 2.2. Visual inspection of the recorded data showed that subtraction of the rectal trace from the bladder trace provided a useful detrusor trace when subjects were ambulant as well as resting. When ambulant, movement caused typical peak-to-peak pressure variability in the bladder and rectal traces of approximately 30 +/- 20 cm. water (mean and standard deviation of peak-to-peak pressure for typical ambulant 5-minute sections for each patient), which after subtraction was reduced on the detrusor trace to 10 +/- 5 cm. water. The equivalent figures when resting were 9 +/- 5 cm. water, subtracting to less than 5 cm. water for the detrusor. Further measurements also were calculated for the whole of each trace. The system provided good quality recordings and should prove useful in future evaluations of natural fill urodynamic studies.

We investigated 41 men with chronic retention of urine owing to bladder outflow obstruction by long-term monitoring of bladder pressure and conventional cystometry to determine the relationship between detrusor pressure and upper tract dilatation. We confirmed that high pressures during conventional filling cystometry were common in men with upper tract dilatation. However, important differences were demonstrated between long-term monitoring and conventional cystometry. The pressure increase during the natural filling phase of long-term monitoring was significantly smaller than that during conventional cystometry. Detrusor instability was found in 88 per cent of the men during long-term monitoring but in only 51 per cent during conventional cystometry (p less than 0.001). High frequency unstable detrusor contractions during long-term bladder pressure monitoring were associated significantly with upper tract dilatation (p less than 0.0001) and correlated significantly with impairment of glomerular filtration rate (rs equals -0.7339, p less than 0.001).

We assessed 6 methods for calculating bladder volume from ultrasonic cross-sectional scans. The technique that used the largest number of features from the scans gave the best results. For volumes greater than 150 ml. an accuracy of 0.87 and repeatability of +/- 9 per cent (standard deviation) were obtained.