We established the longitudinal changes in bladder contractility and compliance as a result of urethral obstruction using a guinea pig model.
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.
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.
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.
[Show abstract][Hide abstract] ABSTRACT: Background
Blood oxygen saturation (BOS) is decreased in a low-compliant, overactive obstructed bladder. The objective of this study is to determine the effect of Sildenafil (SC) on bladder function and BOS) in an in vivo animal model of bladder outlet obstruction.
Thirty-two guinea pigs; sham operated (n = 8), sham operated + SC (n = 8), urethrally obstructed (n = 8) and urethrally obstructed + SC (n = 8) were studied during an 8 week period. BOS of the bladder wall was measured by differential path-length spectroscopy (DPS) before obstruction, at day 0, and at week 8. The bladder function was evaluated by urodynamic studies every week.
Before surgery and after sham operation all study parameters were comparable. After sham operation, bladder function and BOS did not change. In the obstructed group the urodynamic parameters were deteriorated and BOS was decreased. In the group obstruction + SC, bladder compliance remained normal and overactivity occurred only sporadic. BOS remained unchanged compared to the sham group and was significantly higher compared to the obstruction group.
In an obstructed bladder the loss of bladder function is accompanied by a significant decrease in BOS. Treatment of obstructed bladders with SC yields a situation of high saturation, high bladder compliance and almost no overactivity. Maintaining the microcirculation of the bladder wall might result in better bladder performance without significant loss of bladder function. Measurement of BOS and interventions focussing on tissue microcirculation may have a place in the evaluation / treatment of various bladder dysfunctions.
[Show abstract][Hide abstract] ABSTRACT: We present a technique for measuring urinary flow rates with ultrasound in male infants and children.
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.
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.
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.
The Journal of Urology 09/2001; 166(3):1058-61. DOI:10.1097/00005392-200109000-00082 · 4.47 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We determine the etiology and treat the specific pathophysiology of the valve bladder syndrome.
Defined as persisting or progressive severe hydroureteronephrosis without residual or recurrent obstruction, the valve bladder syndrome developed in 18 boys who underwent successful ablation of the posterior urethral valve. Serial radiographic, renal function, renographic, urodynamic and perfusion studies were performed for a mean time of 11 years.
The cause of the valve bladder syndrome proved to be sustained bladder over distention due to a combination of polyuria with 24-hour urine volume greater than 2 l. in 10 boys, impaired bladder sensation in 18 and residual urine volume in 14. Treatment of over distention during the daytime alone was unsuccessful. Nocturnal bladder emptying was performed with an indwelling nighttime catheter, intermittent nocturnal catheterization and/or frequent nocturnal double voiding. Hydronephrosis markedly improved once nocturnal bladder emptying was started and was comparable to the results after urinary diversion.
The valve bladder syndrome is not due to a permanent prenatal alteration in bladder anatomy and function. Instead, it appears to result from sustained postnatal bladder over distention due to a combination of polyuria, impaired bladder sensation and residual urine volume, which represent sequelae of prenatal valve injury. These factors synergize to prevent bladder normalization after valve ablation and progressively reduce functional bladder capacity to maintain bladder over distention. Bladder decompensation, upper tract dilation, and renal injury develop and characterize the valve bladder syndrome. Because current therapy, including intermittent catheterization, leaves the bladder full throughout the night, it remains markedly over distended. Nocturnal bladder emptying is the specific antidote for this pathophysiological situation, and results in prompt and impressive improvement or elimination of hydronephrosis in these and similar groups of patients. This response to nocturnal bladder emptying suggests that the bladder is not the primary cause for the valve bladder syndrome.
The Journal of Urology 02/2002; 167(1):291-7. DOI:10.1016/S0022-5347(05)65453-5 · 4.47 Impact Factor
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