Basics of pressure-flow studies

ICS-SUFU standard: Theory, terms, and recommendations for pressure-flow studies performance, analysis, and reporting. Part 2: Analysis of PFS, reporting, and diagnosis

AIMS

The Working Group (WG), initiated by the International Continence Society (ICS) Standardisation Steering Committee and supported by the Society of Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction, has revised the ICS Standard for pressure-flow studies of 1997.

METHODS

Based on the ICS standard for developing evidence-based standards, the WG developed this new ICS standard in the period from May 2020 to December 2022. A draft was posted on the ICS website in December 2022 to facilitate public discussion and the comments received have been incorporated into this final release.

RESULTS

The WG has recommended analysis principles for the diagnosis of voiding dysfunction for adult men and women without relevant neurological abnormalities. New standard terms and parameters for objective and continuous grading of urethral resistance (UR), bladder outflow obstruction (BOO) and detrusor voiding contraction (DVC) are introduced in this part 2 of the standard. The WG has summarized the theory and recommendations for the practice of pressure-flow study (PFS) for patients in part 1. A pressure-flow plot is recommended for the diagnosis of every patient, in addition to time-based graphs. Voided percentage and post void residual volume should always be included in PFS analysis and diagnosis. Only parameters that represent the ratio or subtraction of pressure and synchronous flow are recommended to quantify UR and only parameters that combine pressure and flow in a product or sum are recommended to quantify DVC. The ICS BOO index and the ICS detrusor contraction index are introduced in this part 2 as the standard. The WG has suggested clinical PFS dysfunction classes for male and female patients. A pressure-flow scatter graph including every patient's pdet at maximum flow (pdetQmax ) with maximum flow rate (Qmax ) point should be included in all scientific reports considering voiding dysfunction.

CONCLUSION

PFS is the gold standard used to objectively assess voiding function. Quantifying the dysfunction and grading of abnormalities are standardized for adult males and females.

Overactive bladder (OAB): a failed concept needing revision to accommodate an external anatomical control system

THESIS AND AIMS

In 45 years, the definitions and practice of the urodynamically based overactive bladder (OAB)/detrusor overactivity (DO) system have failed to adequately address pathogenesis and cure of urinary urge incontinence, frequency and nocturia.

METHODS

We analysed the OAB syndrome with reference to the Integral Theory paradigm's (ITS) binary feedback system, where OAB in the female is viewed as a prematurely activated, but otherwise normal micturition caused mainly, but not entirely, by ligament damage/laxity. The ITS Clinical Assessment Pathway which details the relationships between structural damage (prolapse), ligaments and dysfunction (symptoms) is introduced.

RESULTS

The ITS was able to "better explain" OAB pathophysiology in anatomical terms with reference to the binary model. The phasic patterns diagnostic of "detrusor overactivity" are explained as a struggle for control by the closure and micturition reflexes. The exponentially determined relationship between urethral diameter and flow explains why obstructive patterns occur, why they do not and why urine may leak with no recorded pressure. Mechanically supporting ligaments ("simulated operations") during urodynamic testing can improve low urethral pressure, negative pressure during coughing with SUI and diminish urge sensation or even DO patterns, transforming urodynamics from non-predictive test to accurate predictor of continence surgery results. High cure rates for OAB by daycare repair of damaged ligaments is a definitive test of the binary system's validity.

CONCLUSION

Conceptual progression of OAB to the Integral Theory paradigms's prematurely activated micturition validates OAB component symptoms as a syndrome, explains pathogenesis, and unlocks a new way of understanding, diagnosing, treating and researching OAB.

Estimation of bladder contractility from intravesical pressure-volume measurements

AIMS

To describe parameters from urodynamic pressure recordings that describe urinary bladder contractility through the use of principles of muscle mechanics.

METHODS

Subtracted detrusor pressure and voided flow were recorded from patients undergoing filling cystometry. The isovolumetric increase of detrusor pressure, P, of a voluntary bladder contraction before voiding was used to generate a plot of (dP/dt)/P versus P. Extrapolation of the plot to the y-axis and the x-axis generated a contractility parameter, v_CE (the maximum rate of pressure development) and the maximum isovolumetric pressure, P₀ , respectively. Similar curves were obtained in ex vivo pig bladders with different concentrations of the inotropic agent carbachol and shown in a supplement.

RESULTS

Values of v_CE , but not P₀ , diminished with age in female subjects. v_CE was most significantly associated with the 20-80% duration of isovolumetric contraction t_20-80 ; and a weaker association with maximum flow rate and BCI in women. P₀ was not associated with any urodynamic variable in women, but in men was with t_20-80 and isovolumetric pressure indices.

CONCLUSIONS

The rate of isovolumetric subtracted detrusor pressure (t_20-80 ) increase shows a very significant association with indices of bladder contractility as derived from a derived force-velocity curve. We propose that t_20-80 is a detrusor contractility parameter (DCP). Neurourol. Urodynam. 36:1009-1014, 2017. © 2016 Wiley Periodicals, Inc.

Pressure flow studies in men and women

There are well established pressure flow criteria and nomograms for urinary obstruction in men. The pressure flow criteria for female urinary obstruction are not well established due to differences in female voiding dynamics as compared to men. Typically, other information such as radiographic data and clinical symptoms are needed to facilitate the diagnosis. Detrusor underactivity remains a poorly studied clinical condition without definitive urodynamic diagnostic criteria. Modalities proposed for objective analysis of detrusor function such as power (watt) factor, linear passive urethral resistance relation and BCI nomogram were all developed to analyze male voiding dysfunction. Overall, further investigation is needed to establish acceptable urodynamic criteria for defining detrusor underactivity in women.

Micturitional urethral pressure profilometry for the diagnosis, grading, and localization of bladder outlet obstruction in adult men: a comparison with pressure-flow study

OBJECTIVE

To investigate the accuracy of micturitional urethral pressure profilometry (MUPP) for diagnosis, grading, and localization of bladder outlet obstruction (BOO) in men with obstructive lower urinary tract symptoms.

METHODS

This prospective study included adult men with voiding symptoms qualifying for urodynamics (UDS). Patients with urethral stricture, urinary-tract infection, and inflammatory diseases of the bladder were excluded. Patients were subjected to UDS followed by VCUG the same day. UDS was performed using Solar Silver (MMS International, Enschede, the Netherlands) and included uroflowmetry, resting cystometry with UPP, pressure-flow study with MUPP, and perineal surface-electromyography. The study was performed in accordance with International Continence Society Good Urodynamic-practice Guidelines (2002). VCUG was considered the gold standard for presence and localization of BOO.

RESULTS

A total of 64 male patients with mean age 53.3 ± 17.8 years and International Prostate Symptom Score 17.2 ± 6.8 completed the study. Uroflowmetry revealed maximum urine flow 10.1 ± 7.1 mL/s, voided-volume 218.9 ± 161.6 mL, and postvoid residue 129.8 ± 126.5 mL. For diagnosis of BOO, Abrams-Griffith number, Schaefer obstruction-grades, and obstruction-coefficient had weak agreement with VCUG (Cohen's kappa k <0.20), whereas urethral closure-pressure (Pclo) had strong agreement (k = 0.78). For grading, Pclomax had a significant positive linear correlation with Abram-Griffiths number (R(2) = 0.562; P = .0001). MUPP was able to localize the site of obstruction correctly in 55 of 57 obstructed patients.

CONCLUSION

MUPP is highly accurate in diagnosis, grading, and localization of BOO in men with voiding dysfunction. It might be a useful supplement to VCUG/UDS.

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

AIM

To non-invasively study if compensation and decompensation occurs in the urinary bladder of healthy male volunteers in response to benign prostatic enlargement (BPE) using the condom catheter method.

METHODS

Between 2001 and 2010, 1,020 healthy male volunteers were included in a longitudinal study based on three non-invasive urodynamic examinations during a 5-year follow-up. Inclusion criteria were an informed consent, the ability to void in a normal standing position and a minimum free flow rate of 5.4 ml/sec. Study parameters were prostate volume (PV), maximum free urinary flow rate (Q(max)) and bladder contractility, quantified by the maximum isovolumetric bladder pressure, measured in the condom (P(cond.max)). Volunteers also completed the International Prostate Symptom Score Form (IPSS).

RESULTS

Within limitations, the included volunteers had a flat age distribution between 38 and 72 years. This made it possible to combine longitudinal analysis in a 5-year observation interval, with cross sectional analysis in a 35-year age range. Longitudinal analysis showed that with increasing age, PV increased with 1.9% per year, whereas Qmax decreased with 1.1% per year. IPSS increased with 1.1% per year when volunteers were older than 55 years. P(cond.max) increased during the 5-year longitudinal follow-up, but not in the cross sectional analysis.

CONCLUSIONS

The difference between cross sectional and longitudinal results of the P(cond.max) may have been caused by compensation of the urinary bladder resulting in a selection effect. This would imply that compensation is a relatively fast process, taking approximately 5 years.

Noninvasive 2-dimensional monitoring of strain in the detrusor muscle in patients with lower urinary tract symptoms using ultrasound strain imaging

PURPOSE

Pressure flow studies and filling cystometry are currently the standard diagnostic urodynamic tests for lower urinary tract symptoms. A noninvasive ultrasound based method for 2-dimensional monitoring of deformation (or strain) in the detrusor muscle may provide insight into detrusor muscle structural and dynamic properties related to pressure in physiological and disease conditions.

MATERIALS AND METHODS

In a male patient population with lower urinary tract symptoms, strain in the detrusor muscle (perpendicular to the bladder wall) was estimated based on 2-dimensional radio frequency ultrasound imaging. The estimated strain was correlated to detrusor pressure and urinary flow rate using Spearman's correlation coefficient.

RESULTS

Twenty men (mean ± SD age 66 ± 6 years) with lower urinary tract symptoms were included in the study. Ultrasound data acquisition was successful in 13 patients. In 7 patients data acquisition failed due to out-of-plane motion of the bladder wall during voiding or as a result of patient movement during acquisition. The estimated strain correlated positively with detrusor pressure in the 5 patients with an isovolumetric detrusor contraction (Spearman's 0.70-0.99, p <0.05). Of 8 patients with urinary voiding during detrusor muscle contraction this correlation was significantly positive in 5 patients (Spearman's 0.52-0.81, p <0.05).

CONCLUSIONS

In 13 of 20 patients with lower urinary tract symptoms we demonstrated that strain in the detrusor muscle can be estimated using ultrasound imaging. The estimated strain correlated positively with the detrusor pressure. Optimal results were obtained in the pre-voiding phase, suggesting that ultrasound strain imaging can possibly be used to monitor detrusor muscle activity in real time.

Bladder contractility and urethral resistance relation: what does a pressure flow study tell us?

Hydrodynamic analysis of a pressure flow study is the only reliable method to determine the presence or absence of a bladder outlet obstruction, especially benign prostatic obstruction. To interpret the results of pressure flow study in benign prostatic obstruction, understanding the outlines of the basic theory about evaluation of the relationship between bladder contractility and urethral resistance relation is of paramount importance. In contrast, hydrodynamic analysis of pressure flow study in conditions other than benign prostatic obstruction is complicated by the limits of theories about the hydrodynamics of the lower urinary tract. In this review, the proposed hydrodynamic theories about the relationship between bladder contractility and urethral resistance relation are outlined. Then, problems encountered in the application of hydrodynamic analysis of pressure flow study to diseases other than benign prostatic obstruction are discussed.

Bladder, bowel, and sexual dysfunction in Parkinson's disease

Bladder dysfunction (urinary urgency/frequency), bowel dysfunction (constipation), and sexual dysfunction (erectile dysfunction) (also called “pelvic organ” dysfunctions) are common nonmotor disorders in Parkinson's disease (PD). In contrast to motor disorders, pelvic organ autonomic dysfunctions are often nonresponsive to levodopa treatment. The brain pathology causing the bladder dysfunction (appearance of overactivity) involves an altered dopamine-basal ganglia circuit, which normally suppresses the micturition reflex. By contrast, peripheral myenteric pathology causing slowed colonic transit (loss of rectal contractions) and central pathology causing weak strain and paradoxical anal sphincter contraction on defecation (PSD, also called as anismus) are responsible for the bowel dysfunction. In addition, hypothalamic dysfunction is mostly responsible for the sexual dysfunction (decrease in libido and erection) in PD, via altered dopamine-oxytocin pathways, which normally promote libido and erection. The pathophysiology of the pelvic organ dysfunction in PD differs from that in multiple system atrophy; therefore, it might aid in differential diagnosis. Anticholinergic agents are used to treat bladder dysfunction in PD, although these drugs should be used with caution particularly in elderly patients who have cognitive decline. Dietary fibers, laxatives, and “prokinetic” drugs such as serotonergic agonists are used to treat bowel dysfunction in PD. Phosphodiesterase inhibitors are used to treat sexual dysfunction in PD. These treatments might be beneficial in maximizing the patients' quality of life.

Bladder and bowel dysfunction in Parkinson's disease

Bladder dysfunction (urinary urgency/frequency) and bowel dysfunction (constipation) are common non-motor disorders in Parkinson's disease (PD). In contrast to motor disorder, the pelvic autonomic dysfunction is often non-responsive to levodopa treatment. Brain pathology mostly accounts for the bladder dysfunction (appearance of overactivity) via altered dopamine-basal ganglia circuit, which normally suppresses the micturition reflex. In contrast, peripheral enteric pathology mostly accounts for the bowel dysfunction (slow transit and decreased phasic contraction) via altered dopamine-enteric nervous system circuit, which normally promotes the peristaltic reflex. In addition, weak strain and paradoxical anal contraction might be the results of brain pathology. Pathophysiology of the pelvic organ dysfunction in PD differs from that in multiple system atrophy; therefore it might aid the differential diagnosis. Drugs to treat bladder dysfunction in PD include anticholinergic agents. Drugs to treat bowel dysfunction in PD include dietary fibers, peripheral dopaminergic antagonists, and selective serotonergic agonists. These treatments might be beneficial not only in maximizing patients' quality of life, but also in promoting intestinal absorption of levodopa and avoiding gastrointestinal emergency.

Preliminary communication: Urodynamic assessment of donepezil hydrochloride in patients with Alzheimer's disease

BACKGROUND AND AIMS

Donepezil hydrochloride, a central cholinergic drug, is widely used for improving cognitive decline in Alzheimer's disease (AD). We investigated whether donepezil might affect the lower urinary tract (LUT) function in AD.

METHODS

Alzheimer's Disease Assessment Scale cognitive subscale (ADAS-cog) (0-70, increase as impairment), urinary questionnaire, and electromyography (EMG)-cystometry were performed in eight patients with AD before and after treatment with 5 mg/day of donepezil.

RESULTS

The first assessment (before donepezil) showed moderate cognitive decline in the patients as a mean ADAS-cog score of 27.0 (range: 17-35) (normal < 15). Seven patients had urinary symptoms including urinary urgency incontinence in five. EMG-cystometry revealed neurogenic detrusor overactivity in seven with a mean detrusor pressure of 44.9 cm H(2)O (20-101), mean bladder capacity of 202 ml (20-412), and post-void residuals in none. The second assessment (3 months after donepezil) showed a decrease in the ADAS-cog score to 23.3 (11-35) though without statistical significance. Urinary incontinence disappeared in one and none had a new onset of incontinence. EMG-cystometry revealed an increase in the detrusor pressure on overactivity to 54.1 cm H(2)O (20-122), but also an increase in the bladder capacity to 234 ml (80-400), and post-void residuals in one (40 ml).

CONCLUSION

Although the number of our patients was small, it seems possibly that donepezil could ameliorate cognitive function without serious adverse effects on the LUT function in patients with AD.

Comparison of voiding parameters in men and women with lower urinary tract symptoms

AIM

The aim of this study was to compare voiding parameters by using urodynamic investigations in men and women with lower urinary tract symptoms (LUTS).

METHODS

A total of 164 individuals (76 men and 88 women) completed the International Prostate Symptom Score (IPSS) and underwent a detailed urodynamic investigation. Patients were stratified by voiding function, which included bladder voiding efficiency (BVE) of < 80% and of >or= 80%.

RESULTS

IPSSs were similar in the men and women except for voiding symptoms for those with a BVE of >or= 80% (12 for men vs. 9 for women, P=0.016). When voiding parameters were compared according to BVE in men and women, respectively, maximum flow rate (Q(max)) (P=0.002), average flow rate (Q(ave)) (P=0.003), voided volume (P=0.037), post-void residual (PVR) (P<0.001), and bladder outlet obstruction index (P=0.016) were different for men with a BVE of < 80% and men with a BVE of >or= 80%. However, for women with a BVE of < 80% or >or= 80%, PVR (P<0.001), detrusor pressure at maximum flow rate (P=0.022), and opening detrusor pressure (P=0.024) were different.

CONCLUSIONS

The voiding parameters of women differ from those of men according to voiding function. The present results show that a pressure-flow study may represent a difference according to BVE in women as well as in men. Our findings suggest that opening detrusor pressure in women reflects the urethral and detrusor during voiding phase accurately as detrusor pressure at maximum flow rate does.

Micturitional disturbance in a patient with a spinal cavernous angioma

A 58-year-old woman had a 3-year history of numbness in the right leg, which developed into thoracic transverse myelopathy and urinary retention. After referral to our department, MRI scans revealed a lesion with a target appearance at the T10-11 spinal cord with multiple silent cerebral lesions, which confirmed the diagnosis of cavernous angioma. Gamma-knife surgery was not indicated, considering the risk of adverse effects. The patient gradually became able to urinate, but had urge urinary incontinence. The first urodynamic studies (conducted 3 months after full clinical manifestations of transverse myelopathy) showed detrusor hyperreflexia (DH), decreased bladder sensation during bladder filling, detrusor-sphincter dyssynergia (DSD), and weak detrusor on voiding. However, urinary retention appeared again without change of neurologic signs. The second urodynamic studies (conducted 2 months later) showed less marked DH during bladder filling, and equivocal DSD but marked weak detrusor on voiding. The patient started taking oral prazosin hydrochloride (6 mg/day), which gradually ameliorated her voiding difficulty. Lesions in the lateral and dorsal columns of the spinal cord seem to be responsible for the micturitional disturbance in our patient with spinal cavernous angioma.

Factors associated with voiding function in women with lower urinary tract symptoms: a mathematic model explanation

AIMS

The aim of this study was to explore the relationship between voiding function and factors such as age, gravidity, parity, menopause, and anterior vaginal wall relaxation.

METHODS

One hundred twenty-five women were identified from urodynamic records, 83 premenopausal and 42 postmenopausal. All had had a sonographic assessment of the lower urinary tract and a full urodynamic study, including a pressure-flow study. None had diabetes mellitus, overt neurologic disease, pelvic surgery, anticholinergic medication or estrogen therapy, or voiding difficulty symptoms. Voiding parameters included the following urodynamic variables: maximum flow rate, average flow rate, residual urine, the ratio of residual urine to total bladder volume on spontaneous uroflowmetry, maximum flow rate, and detrusor pressure at maximum flow on a pressure-flow study.

RESULTS

Uroflow rates were significantly correlated with age, parity, and urethral mobility. As a whole, the scatter plots of maximum and average flow rates versus voided volume on uroflowmetry displayed a significant correlation (P < 0.0001 and P < 0.0001, respectively). But, there was no association between maximum flow rate and detrusor pressure at maximum flow in the pressure flow study (P = 0.132). Age, menopause, parity, and urethral mobility may have affected the correlation on uroflowmetry but have no effect on pressure-flow plot. On subgroup analysis, significant correlation was identified only in women aged between 30 and 70, with parity greater than three, and urethral mobility greater than 70 degrees. These groups all had a reduced urethral pressure profile.

CONCLUSIONS

Age, menopause, parity, and urethral mobility may change the hydrodynamics of the lower urinary tract and have varying impact on the voiding function by altering urethral distensibility. Moreover, poor detrusor power in the postmenopausal women may complicate the analysis of voiding function.

Videourodynamic and sphincter motor unit potential analyses in Parkinson's disease and multiple system atrophy

OBJECTIVES

Urinary dysfunction is a prominent autonomic feature in Parkinson's disease (PD) and multiple system atrophy (MSA), which is not only troublesome but also a cause of morbidity in these disorders. Recent advances in investigative uroneurology offer a better insight into the underlying pathophysiology and appropriate management for urinary dysfunction.

METHODS

twenty one patients with PD (15 men, six women, mean age 64 (49-76), mean disease duration 4 years (1-8 years), median Hoehn and Yahr grade 3 (1-4), all taking 300 mg/day of levodopa (100-500 mg)) and 15 with MSA (eight men, seven women, mean age 59 (48-72), mean disease duration 3 years (0.5-6 years)) were recruited. Videourodynamic and sphincter motor unit potential analyses in the patients with PD and MSA were carried out, looking for distinguishing hallmarks that might be useful in the differential diagnosis of these two diseases.

RESULTS

Urinary symptoms were found in 72% of patients with PD and in 100% with MSA. Filling phase abnormalities in the videourodynamic study included detrusor hyperreflexia in 81% of patients with PD and 56% with MSA, and uninhibited external sphincter relaxation in 33% of patients with PD and 33% of those with MSA. However, open bladder neck at the start of filling was not seen in patients with PD but was present in 53% of those with MSA, suggestive of internal sphincter denervation. Sphincter motor unit potential analysis showed neurogenic motor unit potentials in 5% of patients with PD and in 93% of those with MSA, suggestive of external sphincter denervation. On voiding, detrusor-external sphincter dyssynergia was not seen in patients with PD but was present in 47% of those with MSA. Pressure-flow analysis showed that the Abrams-Griffiths number, a grading of urethral obstruction (outflow obstruction >40), in PD (40 in women and 43 in men) was larger than that in MSA (12 in women and 28 in men). Weak detrusor in PD (66% of women and 40% of men) was less common than that in MSA (71% of women and 63% of men). Postmicturition residuals >100 ml were absent in patients with PD but were present in 47% of patients with MSA.

CONCLUSION

Patients with PD had less severe urinary dysfunction with little evidence of internal or external sphincter denervation, by contrast with the common findings in MSA. The findings of postmicturition residuals >100 ml, detrusor-external sphincter dyssynergia, open bladder neck at the start of bladder filling, and neurogenic sphincter motor unit potentials are highly suggestive of MSA.

Pressure flow study data in a group of asymptomatic male control patients 45 years old or older

PURPOSE

The role of pressure flow studies in the routine evaluation of patients with benign prostatic hyperplasia remains a controversial issue in urological practice. There are little data on age matched asymptomatic control groups. We evaluated pressure flow findings in such a group.

MATERIALS AND METHODS

A total of 24 male patients 47 to 80 years old (mean age 62.5) attending a general surgical clinic were recruited for study after ethical committee approval. The volunteers had never sought medical attention for urinary symptoms and did not perceive themselves as having a urological problem. Volunteers were assessed by International Prostate Symptom Score (I-PSS) and Madsen symptom score, clinical examination, free uroflowmetry, post-void residual ultrasound, repeat pressure flow studies and transrectal ultrasonography. Pressure flow tracings were manually analyzed for standard urodynamic values and the degree of bladder outflow obstruction according to recognized International Continence Society, Abrams-Griffith nomogram, linear passive urethral resistance relation and urethral resistance factor classifications.

RESULTS

Median I-PSS was 2.0 (interquartile range 1.2 to 5.7). For I-PSS quality of life the median was 1.0 (interquartile range 0.75 to 2.0). On pressure flow studies 3 patients (13%) had unequivocal obstruction, 7 (29%) were in the equivocal area and 14 (58%) had no obstruction, while 15 (63%) had unstable contractions on medium fill cystometry.

CONCLUSIONS

The data show that a surprising number of apparently normal men are obstructed by commonly used criteria. This finding confirms asymptomatic obstruction, suggesting that obstruction may be less important in the development of symptoms than previously thought. Also, until the natural history of obstruction is more clearly defined surgery in obstructed asymptomatic patients is probably unwise.

Neurogenic failures of the external urethral sphincter closure and relaxation; a videourodynamic study

Urinary urgency and voiding difficulty are common features in neurological diseases, which can be attributed to dysfunction of the urethral sphincter and the detrusor. However, little is known about dynamic sphincter behaviour in neurological diseases. The present study aimed at investigating neurogenic failures of the external urethral sphincter closure and relaxation by videourodynamic study. We recruited 44 neurological patients with urinary urgency and frequency, 27 men and 17 women, mean age 61 years, and 28 of them had voiding difficulty as well. None had abnormal finding of digital examination or ultrasound echography of the pelvic organs. Using triple-lumen 7F catheter under X-ray fluoroscope, we measured detrusor pressure, external urethral sphincter pressure (Pura) and external sphincter EMG in all patients. We also performed pressure-flow study and obtained the Abram-Griffiths (AG) number, a numerical grade of obstruction. During filling 30 had detrusor hyperreflexia. EMG-cystometry showed uninhibited external sphincter relaxation (UESR) in eight patients, seven of whom had detrusor hyperreflexia as well. Patients with UESR showed an abnormal reduction of Pura, mean reduction 64 +/- 27 cmH2O (mean +/- standard deviation). During UESR the Pura and EMG activity fluctuated, and fluoroscopic image showed bladder neck opening in four with extreme urge sensation, including one without detrusor hyperreflexia. During an attempt of voiding three patients with voiding difficulty had detrusor-external sphincter dyssynergia (DESD) with detrusor contraction and eight had unrelaxing external sphincter without detrusor contraction. Fluoroscopic image showed an incomplete or absent urethral opening at the external sphincter. Four of them had severe straining on voiding together with intermittent increment of EMG activity without a normal funneling of the bladder neck. The mean reduction of Pura during voiding was 6.4 +/- 6.7 cmH2O and 5.0 +/- 9.5 cmH2O (in women and men, respectively) with DESD or unrelaxing external sphincter which was less than 39 +/- 25 cmH2O and 53 +/- 47 cmH2O in those without (P < 0.01). The mean AG number was 15 +/- 21 and 51 +/- 19 (for women and men, respectively) with DESD or unrelaxing external sphincter which was larger than 6.2 +/- 34 and 35 +/- 22 in those without (P < 0.05). In conclusion, UESR and DESD/unrelaxing external sphincter could be a factor for urinary urgency and voiding difficulty in neurological patients, evidence of central dysregulation affecting the Onuf's nucleus and its fibres to the external urethral sphincter.

Comparison of three methods of quantifying urethral resistance in men

OBJECTIVES

To determine how well three methods of quantifying urethral resistance from pressure-flow plots compared in men.

METHODS

The pressure-flow plots of 312 men who attended a Continence Clinic for evaluation of lower urinary tract symptoms were analyzed. The Abrams-Griffiths number (AG), detrusor-adjusted mean PURR [passive urethral resistance relation] factor (DAMPF), and group-specific urethral resistance factor (URA) were obtained for each plot. The correlation coefficients and simple regression equations were computed for AG versus DAMPF and AG versus URA. Using the provisional International Continence Society method for definition of obstruction to categorize the AG values as obstructed, equivocal, or unobstructed, we obtained the corresponding DAMPF and URA values for our study population.

RESULTS

The Pearson correlation coefficient, r, for AG versus DAMPF and AG versus URA was 0.941 and 0.889, respectively. The corresponding regression equations obtained were AG = - 32.6 + (DAMPF)1.27 (95% confidence interval [CI] 1.22 to 1.32) and AG = - 16.4 + (URA) 1.67 (95% CI 1.58 to 1.77). The 5th to 95th percentiles of the DAMPF and URA for men who were obstructed (AG number more than 40) were 56 to 92 and 28 to 71, those for men who were equivocal (AG 20 to 40) were 35 to 62 and 17 to 38, and those for men who were unobstructed (AG less than 20) were 12 to 44 and 5 to 24, respectively.

CONCLUSIONS

The DAMPF and URA were highly correlated to the AG in a linear fashion. Although these parameters were developed differently, they appeared to compare well. When using the DAMPF or URA to quantify urethral resistance, it was possible to estimate the corresponding AG value with reasonable confidence.

Pressure-flow studies of micturition

The purpose of pressure-flow studies is to identify and quantify the abnormalities of bladder function (bladder outlet obstruction) that underlie disorders of voiding already demonstrated in simpler ways. Techniques of measurement and data quality control are of primary importance. Different methods for analyzing bladder outlet obstruction in the male like the Abrams-Griffiths nomogram and the linPURR have different aims but give broadly consistent results. Methods for assessing detrusor contractility and obstruction in the female patient are briefly discussed.