A new technique for dynamic analysis of bladder compliance

A Study of Urodynamic Parameters at Different Bladder Filling Stages for Predicting Upper Urinary Tract Dilatation

Purpose

To identify more accurate predictors of upper urinary tract dilatation (UUTD) in neurogenic bladder (NB) children, we studied the relationship among urodynamic parameters at different bladder filling stages, detrusor leak point pressure (DLPP) and UUTD.

Methods

A total of 158 children (3–16 years) with NB were included and then divided into 2 groups according to whether their NB diagnosis was complicated with UUTD: the UUTD group (39 patients) and those without UUTD group (control group, 119 patients). The bladder filling phase was divided into 3 equal parts: the early, middle, and end filling stages. The bladder compliance (BC) and detrusor pressure (△P_det) at each phase and DLPP at the end filling stage were recorded.

Results

A BC<8 mL/cm H₂O both in the middle and end stages is more specific than a BC<9 mL/cm H₂O in the end stage (72%, 73%, vs. 66%), and △P_det >8 cm H₂O in the early stage, 20 cm H₂O in the middle stage and 25 cm H₂O in the end stage are more sensitive than △P_det >40 cm H₂O in the end stage (82%, 85%, 85%, vs. 49%). A DLPP cutoff value of 20 cm H₂O showed higher sensitivity for predicting UUTD than 40 cm H₂O.

Conclusions

Low BC and a high △P_det in the middle and end filling stages are more accurate factors than classic indicators for predicting UUTD. In addition, a DLPP value of >20 cm H₂O in the end bladder filling stage shows high sensitivity.

Ultrasonographic cystometry for neurogenic bladder using elastography

AIM

Ultrasound shear wave elastography (SWE) has been used to measure elasticity (Young's modulus: YM) in solid organs. It was reported to show a better correlation with intravesical pressure (Pves) than with compliance, supporting its potential use in noninvasive cystometry. Contrariwise, conceptually, YM should be more correlated with compliance than with Pves. To optimize the potential use of YM as a noninvasive urodynamic study, the relationship between YM, Pves, and compliance was reassessed in this study.

METHOD

YM was serially measured using SWE along with bladder filling. To overcome problems inherent to current compliance measurements, modified dynamic compliance was developed from cystometry by a locally weighted scatter plot smoothing algorithm. Then it was matched with YM from SWE. YM was also correlated with Pves. Furthermore, to understand the nature of YM, which was measured by ultrasound, the bladder wall's modulus, which was the mathematical assessment of YM derived from cystometric data, was also calculated and compared.

RESULTS

Thirty-two neurogenic bladder patients were included in this study. YM correlated with Pves (r = .72, p < .0001) better than with modified dynamic compliance (r = -0.43, p < .0001). The correlation of YM with Pves was even higher than that with the calculated bladder wall's modulus (r = .52, p < .0001).

CONCLUSION

YM measured by SWE associates with Pves better than with compliance, confirming the results of previous studies. SWE reflects the integration of both the holding capability of the bladder wall and urine rather than either of one, implying its potential utilization in noninvasive cystometry.

Long-term efficacy and safety of solifenacin in pediatric patients aged 6 months to 18 years with neurogenic detrusor overactivity: results from two phase 3 prospective open-label studies

INTRODUCTION

The standard recommended treatment for neurogenic detrusor overactivity (NDO) is clean intermittent catheterization combined with an antimuscarinic agent. However, the adverse systemic side-effects of oxybutynin, the most widely used agent, are of concern.

OBJECTIVE

To evaluate the efficacy and safety of solifenacin in pediatric patients with NDO, aged 6 months-<5 years and 5-<18 years.

STUDY DESIGN

Two open-label, baseline-controlled, phase 3 studies were conducted in pediatric patients with NDO. Patients were treated with sequential doses of solifenacin oral suspension (pediatric equivalent doses 2.5-10 mg) for 12 weeks to determine each patient's optimal dose, followed by a fixed dose ≥40-week treatment period. Primary efficacy endpoint was change from baseline in maximum cystometric capacity (MCC) after 24 weeks. Secondary endpoints included bladder compliance, bladder volume until first detrusor contraction (>15 cmH₂O), number of overactive detrusor contractions (>15 cmH₂O), maximum catheterized volume (MCV)/24 h, and incontinence episodes/24 h. Safety parameters were treatment-emergent adverse events (TEAEs), serious adverse events, laboratory variables, vital signs, electrocardiograms, and ocular accommodation and cognitive function assessments.

RESULTS

After 24 weeks, MCC had significantly increased compared with baseline in patients aged 6 months -<5 years and 5-<18 years (37.0 ml and 57.2 ml, respectively; P < 0.001; Fig.). Improvement was also observed after 52 weeks' treatment. Significant changes were observed from baseline to week 24 in all secondary endpoints in both age groups: increase in bladder compliance, increase in bladder volume to first detrusor contraction as a percentage of expected bladder capacity, reduction in the number of overactive detrusor contractions, increase in MCV, and decreased incontinence episodes. TEAEs were mostly mild or moderate, and there were no new drug-related TEAEs compared with adult studies. Age-related improvements were noted in ocular accommodation and cognitive function.

DISCUSSION

These long-term multicenter investigations demonstrated the efficacy and safety of solifenacin in pediatric patients with NDO. The observed increases in MCC were clinically relevant and demonstrated that an increase in fluid volume can be accommodated in the bladder prior to reaching intravesical pressures that endanger kidney function and/or are associated with leakage or discomfort. Solifenacin was well tolerated with low incidences of constipation and dry mouth (typically associated with antimuscarinics), central nervous system-related side-effects, and facial flushing.

CONCLUSION

Solifenacin was effective and well tolerated in pediatric patients with NDO, aged 6 months-<18 years, suggesting that it is a viable alternative to oxybutynin, the current standard of care. STUDIES ARE REGISTERED AT CLINICALTRIALS.GOV: NCT01981954 and NCT01565694.

The Role of Genetically Modified Mesenchymal Stem Cells in Urinary Bladder Regeneration

Recent studies have demonstrated that mesenchymal stem cells (MSCs) combined with CD34⁺ hematopoietic/stem progenitor cells (HSPCs) can function as surrogate urinary bladder cells to synergistically promote multi-faceted bladder tissue regeneration. However, the molecular pathways governing these events are unknown. The pleiotropic effects of Wnt5a and Cyr61 are known to affect aspects of hematopoiesis, angiogenesis, and muscle and nerve regeneration. Within this study, the effects of Cyr61 and Wnt5a on bladder tissue regeneration were evaluated by grafting scaffolds containing modified human bone marrow derived MSCs. These cell lines were engineered to independently over-express Wnt5a or Cyr61, or to exhibit reduced expression of Cyr61 within the context of a nude rat bladder augmentation model. At 4 weeks post-surgery, data demonstrated increased vessel number (~250 vs ~109 vessels/mm²) and bladder smooth muscle content (~42% vs ~36%) in Cyr61OX (over-expressing) vs Cyr61KD (knock-down) groups. Muscle content decreased to ~25% at 10 weeks in Cyr61KD groups. Wnt5aOX resulted in high numbers of vessels and muscle content (~206 vessels/mm² and ~51%, respectively) at 4 weeks. Over-expressing cell constructs resulted in peripheral nerve regeneration while Cyr61KD animals were devoid of peripheral nerve regeneration at 4 weeks. At 10 weeks post-grafting, peripheral nerve regeneration was at a minimal level for both Cyr61OX and Wnt5aOX cell lines. Blood vessel and bladder functionality were evident at both time-points in all animals. Results from this study indicate that MSC-based Cyr61OX and Wnt5aOX cell lines play pivotal roles with regards to increasing the levels of functional vasculature, influencing muscle regeneration, and the regeneration of peripheral nerves in a model of bladder augmentation. Wnt5aOX constructs closely approximated the outcomes previously observed with the co-transplantation of MSCs with CD34⁺ HSPCs and may be specifically targeted as an alternate means to achieve functional bladder regeneration.

Bladder function in obstructed men - does age matter?

AIM

The high prevalence of diseases and disabilities in the elderly will therefore impose major future challenges for governments, particularly in social security, health system and social care.

METHODS

Nine hundred and seventy-one men, 40 years or older referred for low urinary tract symptoms (LUTS) evaluation who underwent full urodynamic investigation, were reviewed. Urodynamic parameters were obtained, such as Uroflowmetry, those of Filling Cystometry and those of pressure flow study (PFS).

RESULTS

Mean age was of 66.1 years old. Most the patients included in the analysis were categorized as Schafer score 2-4. Correlation analysis of uroflowmetry parameters revealed statistically significant decrease in voided volume (p = 0.013), Qmax (p = 0.023) with aging. Cystometric parameters revealed significant age-related decrease in bladder capacity (p < 0.001) and bladder compliance (p = 0.004). PFS revealed significant decrease in voiding efficiency (p = 0.029), voided volume (p < 0.001), Qave (p = 0.008) and Qmax (p = 0.048) with progressing age. Age subgroup analyses showed significant differences in voiding efficiency (KW, p = 0.032), voided volume (KW, p < 0.001) and Qave (KW, p = 0.036).

CONCLUSIONS

Age-related changes in voiding function might not be a result of impaired detrusor contractility or increased outflow obstruction, intrinsic causes must be suspected. Changes in the storage function of the bladder represent specific pathophysiological mechanisms influenced by aging.

The clinical significance of poor bladder compliance

AIMS

There is limited data on bladder compliance associated with lower urinary tract dysfunction. The aim of this study was to investigate the decrease in bladder compliance, and the clinical relationship between patterns of increased pressure with neurological disease.

MATERIALS AND METHODS

A retrospective analysis was performed in 5,027 patients with voiding dysfunction between June 2002 and April 2008. The patients with poor compliance (PC) were categorized according to the detrusor pattern of increased pressure: group A (gradual increase), group B (terminal increase), and group C (abrupt increase and plateau).

RESULTS

Patients with PC were found in 170 (3.4%) cases (76 males and 94 females) with 46.5% in group A 44.7%, group B, and 8.8% group C. Bladder trabeculation was more prevalent in patients with PC than among those with normal compliance. Group A had the highest correlation with the incidence of spinal cord injury compared to the other groups. Group B had a higher correlation with a history of pelvic irradiation, radical prostatectomy, and tethered cord syndrome compared to the others. Vesicoureteral reflux was more frequently detected in group A and group C. Group C was positively correlated with the presence of detrusor overactivity and nocturnal enuresis.

CONCLUSIONS

Poor compliance was correlated with the presence of neurological conditions. The gradual increase of detrusor pressure was associated with the development of spinal cord injury, and the terminal increase had an association with a history of treatment to the pelvic cavity.

The clinical significance of rectal contractions that occur during urodynamic studies

PURPOSE

Rectal contractions (RC) while performing filling cystometry are frequently detected, the clinical significance of RC has not been investigated. This study analyzed the relationship between RC and clinical data.

MATERIALS AND METHODS

A retrospective analysis was performed in 5,026 patients with voiding dysfunction between June 2002 and April 2008. The RC were classified according to the maximal amplitude (higher or lower than 15 cmH(2)O) and rhythmicity; group I (rhythmic, high, 4.6%), group II (rhythmic, low, 61.2%), group III (random, high, 2.5%), and group IV (random, low, 31.7%). All the clinical and urodynamic data were made in a retrospective setting for lower urinary tract symptoms and past medical history.

RESULTS

RC were found in 6.5% (188 males and 139 females). Bladder compliance was decreased and bladder trabeculations were more common in patients with RC. The occurrence of RC was correlated with the development of cerebrovascular accidents in males. Among the females, the occurrence of oligopontocerebellar atrophy, spinal lesions, and the cauda equine syndrome were more common. Group I had a correlation with a spinal cord injury in males, bladder trabeculations and vesicoureteral reflux in females; group II was correlated with an idiopathic overactive bladder in both men and women, stress urinary incontinence and mixed urinary incontinence in females. No correlation was found in groups III and IV.

CONCLUSIONS

RC were correlated with neurological disease and non-neurological conditions. The identification of a rhythmic RC should be followed by screening for underlying conditions.

Enhanced objective quantitative cystometric analysis of compliance and contractility

OBJECTIVE

To show, for pressure-time data from cystometrography (CMG), the potential practical clinical application of automatically identified, displayed, analysed and quantified compliance and contractility, as undesirable high-pressure detrusor storage may be caused by inefficient compliance or uninhibited contractions (UNC).

MATERIAL AND METHODS

Bladder contractility was measured by UNC and compliance by relaxed-state detrusor pressure (RSDP), i.e. the detrusor (bladder-abdominal) pressure with all UNC removed. Forty-one CMG examinations were used retrospectively to: (i) validate the separation and identification, by comparing the resulting separate graphs (data) of UNC and RSDP with an expanded time scale for raw vesical and rectal data; (ii) show that the separation is correct by examples; and (iii) show the potential practical utility by results for typical cases.

RESULTS

Separation into RSDP and UNC was correctly identified and plotted. The examples showed the utility and four types of UNC ('high', contractions of >25 cmH(2)O of long duration; 'medium', >25 cmH(2)O of short duration; 'low', 4-25 cmH(2)O of short duration; and 'frequent', of 2-6 cmH(2)O).

CONCLUSIONS

UNCs as small as 2 cmH(2)O can be detected and measured. The explicit enhanced estimate of compliance and contractility will be useful in the follow-up when comparing different patients and studies, and assist in more appropriate diagnosis and treatment. Because the treatment for bladders with poor contractility differs greatly from those with detrusor instability, the ability to reliably and accurately differentiate between these causes is important.

Detrusor pressure rise in a normal bladder

OBJECTIVE

To determine the detrusor pressure rise of a normal bladder (P(cap,NL)) when filled to capacity.

PATIENTS AND METHODS

Twenty-four patients with an apparently normal bladder, i.e. with symptoms but whose cystometrogram (CMG) showed no pathology of any kind and a near-normal pressure vs volume plot, were selected from 218 clinical CMGs. A straight line was fitted to the PV plot of these CMGs and then the P(cap,NL) calculated, e.g. by a straight line extending to the point of the normal expected cystometric bladder capacity (V(cap.NL)). Published data relative to P(cap,NL) were evaluated and compared with the values obtained.

RESULTS

The mean (range) P(cap,NL) was 6 (4.5-7) cmH2O for patients with apparently normal bladders infused at the maximum physiological diuresis (MPD). This value was substantiated by three other studies of published values. The P(cap,NL) was 6 cmH2O at infusion rates of 10% of glomerular filtration rate (GFR), 10 cmH2O at 20% of GFR and 7-15 cmH2O for 3-10 times the infusion rate of 10% of GFR.

CONCLUSION

P(cap,NL) is independent of age, size and sex and, at constant infusion rates of approximately MPD, will be 6. For infusion rates up to 35 mL/min, it is in the range of 6-15 cmH2O.

The effects of intravesical lidocaine on bladder dynamics of children with myelomeningocele

PURPOSE

Other studies have suggested that intravesical lidocaine may temporarily improve bladder dynamics but details of these effects and their application to children have not been examined. We evaluated the effects of intravesical lidocaine on bladder urodynamics of children with myelomeningocele and tried to correlate these effects with subsequent clinical response to oral oxybutynin.

MATERIALS AND METHODS

Charts of children with myelomeningocele who had undergone urodynamic examinations from 1992 to 1998 were reviewed retrospectively. In children with uninhibited contractions or poor compliance 150 to 300 mg. lidocaine were instilled for 8 minutes and cystometry was repeated. Changes in bladder capacity and compliance, number of uninhibited contractions and bladder volume at which pressure of 40 cm. H2O was reached were recorded before and after the lidocaine instillation. Clinical response to subsequent treatment with oral oxybutynin was assessed from chart review.

RESULTS

A total of 48 urodynamic studies in 22 girls and 20 boys with a mean age plus or minus standard deviation of 8.3 +/- 5.7 years and myelomeningocele were evaluable. After instillation of lidocaine, urodynamics showed increased bladder capacity in 70.8% of studies (34 of 48), with an average increase in volume of 66% (p <0.05). No change or decreased bladder capacity occurred in 29.2% of studies. Bladder compliance improved in 61.7% of the studies (29 of 47, p <0.05) and worsened in 38.3%. Bladder volume at which the pressure of 40 cm. H2O was reached increased in 77.8% of studies (14 of 18, p <0.05). After lidocaine the number of uninhibited contractions decreased by 3.2 in 56.8% of studies (21 of 37, p <0.05). Correlation of lidocaine induced changes in bladder capacity, compliance and number of uninhibited contractions with improvement on oral oxybutynin was 70.6%, 64.3% and 66.7%, respectively.

CONCLUSIONS

Intravesical lidocaine can improve bladder capacity and compliance and decrease the number of uninhibited contractions in many children with neurogenic bladder caused by myelomeningocele. These observations suggest that intravesical lidocaine has effects on the neurogenic bladder that improve bladder dynamics. Although intravesical lidocaine testing may not reliably predict clinical response to oral oxybutynin at the prescribed dosages, a possible therapeutic role for intravesical lidocaine or similar agents should be explored further.

The effects of intravesical lidocaine on bladder dynamics of children with myelomeningocele

PURPOSE

Other studies have suggested that intravesical lidocaine may temporarily improve bladder dynamics but details of these effects and their application to children have not been examined. We evaluated the effects of intravesical lidocaine on bladder urodynamics of children with myelomeningocele and tried to correlate these effects with subsequent clinical response to oral oxybutynin.

MATERIALS AND METHODS

Charts of children with myelomeningocele who had undergone urodynamic examinations from 1992 to 1998 were reviewed retrospectively. In children with uninhibited contractions or poor compliance 150 to 300 mg. lidocaine were instilled for 8 minutes and cystometry was repeated. Changes in bladder capacity and compliance, number of uninhibited contractions and bladder volume at which pressure of 40 cm. H2O was reached were recorded before and after the lidocaine instillation. Clinical response to subsequent treatment with oral oxybutynin was assessed from chart review.

RESULTS

A total of 48 urodynamic studies in 22 girls and 20 boys with a mean age plus or minus standard deviation of 8.3 +/- 5.7 years and myelomeningocele were evaluable. After instillation of lidocaine, urodynamics showed increased bladder capacity in 70.8% of studies (34 of 48), with an average increase in volume of 66% (p <0.05). No change or decreased bladder capacity occurred in 29.2% of studies. Bladder compliance improved in 61.7% of the studies (29 of 47, p <0.05) and worsened in 38.3%. Bladder volume at which the pressure of 40 cm. H2O was reached increased in 77.8% of studies (14 of 18, p <0.05). After lidocaine the number of uninhibited contractions decreased by 3.2 in 56.8% of studies (21 of 37, p <0.05). Correlation of lidocaine induced changes in bladder capacity, compliance and number of uninhibited contractions with improvement on oral oxybutynin was 70.6%, 64.3% and 66.7%, respectively.

CONCLUSIONS

Intravesical lidocaine can improve bladder capacity and compliance and decrease the number of uninhibited contractions in many children with neurogenic bladder caused by myelomeningocele. These observations suggest that intravesical lidocaine has effects on the neurogenic bladder that improve bladder dynamics. Although intravesical lidocaine testing may not reliably predict clinical response to oral oxybutynin at the prescribed dosages, a possible therapeutic role for intravesical lidocaine or similar agents should be explored further.

Current concepts and controversies in urodynamics

Urodynamics is the dynamic study of the transport, storage, and evacuation of urine by the urinary tract. It is comprised of several tests that, when used individually or collectively, can give information about lower urinary tract function. The components of the urodynamic study are uroflowmetry, cystometry, pressure-flow studies, electromyography, urethral pressure profilometry, leak point pressure measurement, videourodynamics, and ambulatory urodynamics. Familiarity with the recent advances and controversies of each component is essential when using urodynamics to diagnose and treat lower urinary tract dysfunction.

The role of oxybutynin in spinal cord injured patients with indwelling catheters

PURPOSE

The long-term benefits of oral oxybutynin in spinal cord injured patients with indwelling catheters is unknown. We reviewed our experience with this population of men and present the results of our analysis.

MATERIALS AND METHODS

A total of 109 male spinal cord injured patients at the Houston Veterans Affairs Medical Center have been treated with chronic indwelling catheters (80 transurethral and 29 suprapubic). Thirty-eight patients (35%) were identified as using oxybutynin on a regular basis. These patients were compared to those not using oxybutynin with regard to urodynamic parameters and upper tract deterioration. Specifically examined were bladder compliance, bladder leak point pressure, vesicoureteral reflux, hydronephrosis, urolithiasis, febrile urinary tract infections and serum creatinine greater than 2 mg./dl.

RESULTS

The mean duration of indwelling catheter use was 11.9 years (12.4 without oxybutynin and 10.9 on oral oxybutynin). Of the 31 patients with normal compliance (greater than 20 ml./cm. water), 24 (77%) were using oxybutynin (p = 0.001). Bladder leak point pressures were abnormal (greater than 35 cm. water) in 5 of 32 patients (16%) on oxybutynin versus 34 of 60 (57%) without it (p <0.001). Hydronephrosis was present in 15 of 66 patients (23%) without oxybutynin versus 1 of 36 (3%) with oxybutynin (p = 0.009). Febrile urinary tract infections occurred in 4 of 35 patients (11%) versus 17 of 62 patients (27%) with or without oxybutynin, respectively (p = 0.077). No significant differences were found between the 2 groups with regard to reflux, renal scars, stones or elevated serum creatinine.

CONCLUSIONS

It appears that regular use of oxybutynin may be beneficial in spinal cord injured patients who require chronic indwelling catheters for bladder management. Our analysis reveals that patients who take oxybutynin regularly have better bladder compliance, lower bladder leak point pressures and less hydronephrosis. Until a prospective, randomized trial reveals contradicting outcomes, empiric use of oxybutynin in all spinal cord injured patients requiring chronic indwelling catheters seems justified.

Cystometry

Cystometry provides crucial information on which therapy for voiding dysfunction is predicated. The technique of cystometry can be altered to address specific clinical questions; however, the goal of the study is to reproduce the clinical situation being investigated. Specific areas remain to be clarified, including the estimation and interpretation of compliance and the utility of standard versus natural filling methods.

Pediatric renal transplantation into the abnormal urinary tract

Many children with end-stage renal disease have significant urinary tract problems other than irreversible loss of native kidney function. These significant other urinary tract problems, if not corrected prior to transplantation, may significantly increase recipient mortality, graft loss, and patient morbidity. These other urinary tract problems may cause hydroureteronephrosis in the transplanted kidney, lead to an increased incidence of graft rejection, be the source of sepsis after subsequent immunosuppression, and cause hypertension. In addition, pre-existing urinary diversion, large interabdominal masses, or previous cancer require specific pre-transplant management plans. Potential pediatric transplant recipients with other significant urinary tract problems can be classified according to three parameters; anatomical extent, pathology, and pathophysiology of the significant other problems. Particular attention must be paid to pre-existing lower tract problems. Strategy must be worked out pre transplant as to how the lower urinary tract is going to store, hold, and empty urine. The means for assessing the potential recipients and strategies and techniques for correcting pre-existing problems have been summarized in this article.

The effect of pregnancy on rat urinary tract dynamics

We investigated the urodynamics of the renal pelvis and bladder during spontaneous bladder filling and emptying in 13 pregnant and 19 nonpregnant Sprague-Dawley rats to examine the characteristics of the dilated urinary tract in pregnancy. For each group renal pelvic and bladder pressures were measured continuously and simultaneously during various urinary flows, while the bladder was filled and emptied. In pregnant rats the ureter was wider and the renal pelvis was longer and wider than in nonpregnant rats. At urinary flows of 10 to 30 ml/kg. per hour pregnant rats had significantly lower renal pelvic pressures than nonpregnant rats during bladder filling. In addition, pregnant rats had higher bladder compliance and capacity than nonpregnant rats (compliance 0.09 +/- 0.12 ml./cm. water versus 0.05 +/- 0.05 ml./cm. water, p < 0.01 and bladder capacity 0.669 +/- 0.61 ml. versus 0.490 +/- 0.38 ml., p < 0.05). These findings imply that much of the hydroureteronephrosis during pregnancy may relate to increased urinary tract compliance rather than obstruction.

The sensitivity of pressure specific bladder volume versus total bladder capacity as a measure of bladder storage dysfunction

Assessment of bladder storage function requires an accurate measure of bladder capacity and pressure. Pressure specific bladder volume is the volume that a bladder can accommodate at a specific pressure. A total of 21 consecutive children with neurogenic bladders who were candidates for bladder augmentation based on standard clinical criteria (upper urinary tract deterioration, incontinence and infection) was studied to determine the efficacy of pressure specific bladder volume as a measure of bladder dysfunction. Urodynamic indexes were compared to previously established nomograms. All 21 patients had bladder volumes at pressures of 30 cm. water or less, which decreased below the 5th percentile as determined by the nomogram. In 7 patients (33%) normal total bladder capacity was achieved at the expense of elevated storage pressures. Pressure specific bladder volume provides a better measure of bladder storage function than total bladder capacity because it relates volume to intravesical pressure, does not rely on a subjective end point to bladder filling, and is objective and reproducible.

Bladder augmentation: ureterocystoplasty versus ileocystoplasty

The primary advantages of augmentation ureterocystoplasty include the absence of mucus, lack of electrolyte absorption from the augmenting segment and the avoidance of gastrointestinal complications. We tested whether the ureteral patch offers sufficient biomaterial to increase adequately the storage efficiency of dysfunctional bladders. Between April 1989 and November 1992, 8 children with unilaterally dilated and tortuous ureters underwent bladder augmentation using detubularized reconfigured megaureter. Clinical and urodynamic outcomes were compared between these patients and a control group of 8 children matched in age and diagnosis who had undergone ileocystoplasty during the same time. Total bladder capacity, pressure specific bladder volume at pressure less than 30 cm. water, dynamic analysis of bladder compliance, continence and upper tract status were compared between the 2 groups before and after augmentation. Preoperatively, all 16 patients were incontinent with high pressure, small capacity bladders, and all had upper tract changes. Postoperatively, the mean total bladder capacity was 417 ml. in the ureterocystoplasty group and 381 ml. in the ileocystoplasty group (p > 0.05), while the mean pressure specific bladder volume was 413 and 380 ml. (p > 0.05), respectively. Pressure specific bladder volume and dynamic bladder compliance were normal in 7 of 8 patients (87.5%) in the ureterocystoplasty group. All patients in the ileocystoplasty group had normal postoperative urodynamics. We conclude that megaureters subtending effete kidneys may be used to improve the storage function of dysfunctional bladders to the same extent as that achieved with ileum without the complications pursuant to ileocystoplasty, and that the improvement is maintained long term.

Loss of elasticity in dysfunctional bladders: urodynamic and histochemical correlation

To store adequate volumes of urine at low safe pressures an elastic bladder wall is required. We developed 2 new techniques to measure this ability in our urodynamic laboratory: pressure specific bladder volume, which measures the bladder capacity at a given pressure, and dynamic analysis of bladder compliance. Recently, morphometric and histochemical techniques have been used to determine the relative volume of connective tissue in the bladder wall and to measure the 2 major types (I and III) of collagen within the bladder wall. These methods quantitate 3 parameters of bladder ultrastructure: 1) relative volume of per cent connective tissue, 2) ratio of connective tissue to smooth muscle and 3) ratio of type III to type I collagen. These parameters have been shown to be abnormally elevated in patients with dysfunctional bladders compared to normals. The purpose of the study was to describe the ultrastructural changes that occur in the wall of dysfunctional bladders and to determine the ability of these new urodynamic techniques to detect reliably the clinical effect of these histological changes. The study included 29 consecutive patients with dysfunctional bladders necessitating bladder augmentation. All patients had upper tract changes and/or were incontinent despite treatment with clean intermittent catheterization and pharmacotherapy. Preoperative urodynamic evaluation included measurement of the total bladder capacity, pressure specific bladder volume and dynamic analysis of bladder compliance. Full thickness bladder biopsies were obtained from the dome of the bladders during augmentation. The per cent connective tissue and the ratio of connective tissue to smooth muscle were determined for all patients, and 4 unselected patients from this group had the ratio of type III to type I collagen determined. These histological results were compared to previously established normal values. All 29 patients had a decreased pressure specific bladder volume and dynamic analysis of bladder compliance, whereas 9 had a normal total bladder capacity. The per cent connective tissue was 35.19 +/- 2.84 and ratio of connective tissue to smooth muscle was 0.60 +/- 0.08 compared to normal values of 10.6 +/- 0.020 and 0.131 +/- 0.021, respectively (p < 0.05). Ratio of type III to type I collagen was also significantly elevated in the 4 samples analyzed (30.53 +/- 1.37 versus 24.00 +/- 2.50, p < 0.05). We conclude that poor storage function of poorly compliant bladders is secondary to an alteration in the connective tissue content of the bladder wall. Furthermore, these pathological ultrastructural changes are universally reflected by an abnormally low pressure specific bladder volume and dynamic analysis of bladder compliance. This strong association validates the use of these parameters and suggests that they are urodynamic indicators of a loss of elasticity in bladder wall.