Body surface related flow rate nomograms in a normal pediatric population

Uroflow studies for 511 normal pediatric subjects (272 boys, 239 girls) were analyzed statistically. Nomograms relating peak flow to volume voided and body surface were established. An acceptable lower limit for peak flow was obtained from the data and a volume voided range was calculated so that both criteria could be used with 90% probability to define the normal voiding situation. Body surface area was found to be a more reliable index than age in the establishment of nomograms. In the male population the 90% probability applied to a significantly greater volume voided reliability. In the female population mean peak flow rate rose with increased body surface. Finally, in both sexes the 10% lower limit was closer to the regression mean, allowing a tighter distribution around this value.     

Male peak urinary flow rate: relationships to volume voided and age.

We performed 126 studies of replicate voiding in 7 individuals and 552 observations in normal, abnormal or treated male populations with a disposable device that measures peak flow and volume voided. These observations have led us to suggest that a voided volume of 150 ml. be used as the minimum acceptable volume for studies of male subjects in which peak flow is used to define normal versus abnormal voiding. At volumes greater than 150 ml. a straight line describes the relationship between volume voided and peak flow as accurately as the previously suggested hyperbolic curve. Increasing age of men again reveals progressive decrease in peak flow rate no matter what volume is voided. Comparison of peak flow rate, volume voided and age by 3-dimensional graphing was attempted but was found unsuccessful for clinical use. However, 3 biaxial linear graphs may be used to chart effectively the 3 parameters (age, volume and peak flow) and thereby judge normality or abnormality of peak flow rate for any age and volume voided.     

Disposable peak urinary flowmeter estimates lower urinary tract obstruction.

Peak urinary flow rate represents the highest flow rate achieved during a single urination and, as such, represents the patient's best effort at micturition. Peak flow rate, correlated with patient age and volume voided, effectively estimates lower urinary tract obstruction. The 63 normal and 368 abnormal male subjects urinated in privacy into a plastic sterile disposable device (the peakometer), which measured peak flow rate and volume voided. These data plus age, ultimate diagnosis and interval since last urination comprised our data base. Percentage distribution of diagnosis in this population was prostatic obstruction 47.3 per cent, stricture 19.3 per cent, normal 14.6 per cent, prostatitis 8.4 per cent, neurogenic bladder 2 per cent and miscellaneous 8.4 per cent. The average peak flow rate for normal male subjects reaches 27.6 ml. per second, which differs significantly from that for patients with prostatic obstruction--9.4 ml. per second, stricture--10.5 ml. per second, prostatitis--16.3 ml. per second and neurogenic bladder--13.9 ml. per second. The peak flow rate decreased progressively as the age of the subjects increased. We measured average decreases of 10 ml. per second peak flow for every 30 years after age 10. Peak flow rate increases as volume voided increases. Requirements of our measuring device combined with urodynamic responses caused us to select 100 ml. voided as the minimum acceptable volume. With volumes more than this any given individual may deviate plus or minus 10 per cent from the true mean peak flow depending upon volume voided. For practical purposes peak flow, age and volume must be considered to categorize voiding by peak flow rate. With these variables 2 graphs that compare peak flow, age and volume may be used to estimate voiding function for a given male patient. Comparison of peak flow rates, volume voided and voiding interval before and after surgical correction of obstruction documented significant increase in volume voided or in interval between voiding. Peak urinary flow rate measurement by this device predicted normality or abnormality with 90 to 95 per cent accuracy. Therefore, this represents a valid screening test but it does not in itself provide the diagnosis of abnormal urination.     

Voided volumes: normal values and relation to lower urinary tract symptoms in elderly men, a community-based study

Objectives. To determine the normal values of voided volumes and explore the relation between bladder capacity and lower urinary tract symptoms (LUTS) in elderly men.Methods. Data were collected from 1688 men 50 to 78 years old recruited from the population of Krimpen aan den IJssel, The Netherlands. Measurements included self-administered questionnaires (including the International Prostate Symptom Score), a 3-day frequency volume chart, transrectal ultrasonography of the prostate, uroflowmetry, and postvoid residual volume determination.Results. The 24-hour voided volumes were independent of age (median 1506 mL; 25th to 75th percentiles 1160 to 1950). The average volume per void and functional bladder capacity (FBC, defined as the largest single voided volume) declined with advancing age. Moreover, FBC was lower in men with a reduced maximum flow rate (less than 15 mL/s) and independent of the postvoid residual volume. Multivariate analyses showed no significant effect of prostate enlargement on the FBC. FBC was strongly related to LUTS: a low FBC coincided with higher International Prostate Symptom Scores. Multivariate logistic regression analyses revealed that the presence of moderate to severe symptoms (International Prostate Symptom Score greater than 7) was independent of prostate volume, but dependent on age, a reduced flow rate, postvoid residual volume, and FBC.Conclusions. Prospective studies are needed to establish the causal relation between FBC and LUTS. Frequency volume charts are a valid, easy-to-use, noninvasive method to determine FBC as an aspect of urinary tract (dys)function in the evaluation of men with LUTS and to determine treatment options for LUTS.     

Uroflowmetry nomogram in Iranian children aged 7 to 14 years

Background

As the voiding habits of Iranian children differs from other children because of some cultural and religious considerations, we aimed to establish normal reference values of urinary flow rates in Iranian children between 7 to 14 years of age.

Methods

Eight hundred and two uroflowmetry studies were performed on children with no history of a renal, urological, psychological or neurological disorder, between the ages 7 and 14. Five hundred twenty five studies from 192 girls and 335 boys were considered in this study excluding the staccato/interrupted voiding pattern or voided volume less than 20 ml. The voiding volume, the maximum and average urinary flow rates were extensively analyzed.

Results

The maximal and average urine flow rate nomograms were plotted for both girls and boys. Mean maximum urine flow rate was 19.9 (ml/sec) for boys and 23.5 (ml/sec) for girls with a mean voided volume of 142 (ml) for boys and 147 (ml) for girls. Flow rates showed a close association with voiding volume in both sexes. The maximum and average flow rates were higher in girls than in boys, and they showed a significant increase in flow rates with increasing age, where boys did not. The mean maximum urine flow rates (19.9 ml/sec for boys and 23.5 ml/sec for girls) were found to be higher in this study than other studies.

Conclusion

Nomograms of maximal and average flow rates of girls and boys are presented in centile form, which can help the physician to evaluate the response to medical or surgical treatment and be useful for the screening of lower urinary tract disturbances in children, for a wide range of voided volumes.     

Maximum and average urine flow rates in normal male and female populations--the Liverpool nomograms

The study of voiding in men and women has been handicapped by the lack of a normal reference range covering urinary flow rates over a wide range of voided volumes. Normal volunteers (331 males and 249 females) were studied. Each voided once into a calibrated Dantec Urodyn 1000 mictiograph. On a second occasion 282 men and 46 women voided. The maximum and average urine flow rates of the first voids in both sexes were compared with the respective voided volumes. Nomogram charts, in centile form, for both the maximum and average urine flow rates were constructed using statistical transformations of the data. Males showed a significant decline in both urinary flow rates with age, although there was no statistically significant variation in either urine flow rate with respect to first versus repeated voiding. Females showed no statistically significant variation in either urine flow rate with respect to age, parity or first versus repeated voiding. The maximum and average urine flow rates in both sexes showed an equally strong relationship to voided volume. No artificial restriction of voided volume, e.g. minimum 200 ml, appeared appropriate. These nomograms offer reference ranges for both maximum and average urinary flow rates in both sexes covering a wide range of voided volumes (15-600 ml).     

Clinical evaluation of patients with prostatic obstruction: correlation of flow rates with voided, residual or total bladder volume

Previous investigators reported that accurate estimation of average or maximum urinary flow rates required correlation with total bladder volume (voided plus residual volumes). To test this requirement we performed uroflowmetry studies on 124 patients before and 77 patients after prostatectomy. Of the patients 20 were tested on multiple preoperative and postoperative occasions to comprise paired observations. Observations were made on age, voided and residual volumes, voiding duration, and average, maximum and adjusted maximum flow rates. Prostatectomy resulted in significant increases in all flow rates and significant decreases in voiding duration. The procedure had significant effects on reducing residual volume but voided volumes increased and total volume decreased only slightly postoperatively. Preoperative average, maximum and adjusted peak urinary flow rates correlated negatively with residual volume (increasing residual volume correlates with decreasing flow rate). Maximum flow rates correlated positively with voided volume. Whether measured preoperatively or postoperatively no significant correlation was found among average, peak or adjusted flow rates and total bladder volume. The only consistent significant correlation found among voided, residual and total volumes, and other measurements was voiding duration, which increased as any of the aforementioned volumes increased. Comparison of the random total and paired populations revealed no significant difference. Use of voided rather than total volume seems preferred in correlations with maximum urinary flow rates. Determination of residual urine remains necessary as an estimation of emptying failure but it is not required information for determination of flow rates.     

Timed micturition and maximum urinary flow rate in randomly selected symptom-free males

OBJECTIVE: To establish normal ranges for timed micturition, i.e. the time to void the first 100 ml, study its dependency on voided volume and age and compare it to maximum flow rate. MATERIAL AND METHODS: Randomly selected men from the National Register without voiding symptoms were investigated. These 58 men (aged 30-75 years) registered 1286 voidings (median 21 per person) at home with the aid of a portable uroflowmeter. Timed micturition and maximum flow rate were obtained from the same voidings. RESULTS: An increase in timed micturition with an increase in age was confirmed. When estimating normal ranges it was sufficient to use the age groups < or = 55 years and > or = 56 years. Maximum flow rate is shown in nomograms with voided volume. Timed micturition had less dependency on voided volume than maximum flow rate. The normal ranges of timed micturition are < or = 9 s for men aged < or = 55 years and < or = 15 s for those aged > or = 56 years. The true median of timed micturition for men aged > or = 56 years may be 6 s lower or 2.5 s higher than the value of a single measurement. Corresponding figures for maximum flow rate are 5 and 6 ml/s. CONCLUSIONS: Timed micturition has a low dependency on volume and values of < or = 9 s and < or = 15 s are normal for men aged < or = 55 years and > or = 56 years, respectively.     

Normal variation and influence of stress,caffeine intake,and sexual activity on uroflowmetry parameters of a middle-aged asymptomatic cohort of volunteer male urologists

AIMS: To assess normal variations of uroflowmetry in middle-aged asymptomatic male urologists and to analyse the influence of stress, caffeine intake, and sexual activity. METHODS: Thirty-one male urologists from Quebec and Ontario were recruited for this study. All were healthy, not taking any current medications known to interfere with lower urinary tract function, and symptom-free (International Prostate Symptom Score less than 5). Each received two identical flowmeters to keep over a period of 2 weeks, one at home and one in his busiest office. Ten uroflow tracings, with a volume greater than 150 mL, were requested from each of them; five at home and five in the office. A total of 310 flows were analysed. The subjective level of stress, coffee intake, and sexual activity, in the hour before each uroflowmetrogram, was recorded, through a short self-administered questionnaire and stress visual scale. RESULTS: are presented as an average per individual. The voided volume was 331.9 mL, with an SD of 94.8 mL. The voiding time was 32.7 seconds (SD=15.5). The peak flow rate was 20.5 mL/sec (SD=3.9), the mean flow rate was 14.3 mL/sec (SD=3.0), and the time to maximum flow was 7.2 sec (SD=4.0). Subjective levels of stress did not significantly change these parameters. Uroflows were obtained with and without coffee drinking. The voided volume was 337.4 mL (SD=109.2) vs. 290.8 mL (SD=77.3) (P=0.03), and peak flow rate 19.4 mL/sec (SD=4.1) vs. 18.9 mL/sec (SD=3.1) (P=0.49), respectively. CONCLUSIONS: Uroflowmetry parameters and voided volume are highly variable in a normal asymptomatic population. Subjective stress level does not seem to have an influence on these parameters. Coffee intake significantly increases the voided volume but does not change the peak flow rate. These conclusions should be considered when using uroflowmetry parameters as an outcome measure.     

The use of urinary flow rates obtained from voided volumes less than 150 ml in the assessment of voiding ability

The initial slope of the curve relating peak urinary flow rate to voided volume was found to predict an individual's flow rate at bladder volumes of 200 ml or more in normal subjects and those with symptoms of outflow obstruction. The numerical value of this initial slope was found to decline in a hyperbolic fashion with increasing age. A similar decrease was observed for peak urinary flow rates at bladder volumes between 200 and 300 ml. The use of initial slope as an index of voiding ability would appear to be just as effective in discriminating between normal and obstructed men as a single flow rate determination at a large volume and would be of most benefit in those patients unable to void large volumes of urine.     

Peak expiratory flow in rural residents of Tamil Nadu, India.

BACKGROUND: In a country such as India that covers several latitudes, climatic zones, ethnic groups, and dietary habits lung function within the normal population would be expected to vary. Several studies have looked at normal values of peak expiratory flow (PEF) in different regions of urban India but none has looked at rural South India. A study of PEF has now been carried out in a rural population of Tamil Nadu. METHODS: All subjects were of Dravidian stock and lived at sea level with rice as their staple food. Ten five year age groups from 10 to 59 years with 100 males and 100 females in each were studied. Peak flow was measured by mini-Wright peak flow meter, and height was also measured. Regression equations for predicting normal PEF were calculated. RESULTS: Peak flow ranged from 150 to 680 l/min in males and from 150 to 500 l/min in females. Maximum values of PEF were attained at the age of 32.5 years in men and 35.6 years in women. There was a significant linear correlation between height and PEF and a curvilinear relation between age and PEF in both sexes. CONCLUSION: Regression equations are now available for PEF values in normal subjects from rural South India. PEF was related to age and height and values were greatest in the fourth decade.     

Diagnosis of female bladder outlet obstruction and relevance of the parameter area under the curve of detrusor pressure during voiding: preliminary results

PURPOSE: The diagnosis of bladder outlet obstruction in women by pressure flow study may be difficult because there are several definitions of bladder outlet obstruction, several parameters and no standard cutoffs. We evaluated the ability of pressure flow studies to separate women into unobstructed, equivocal and obstructed groups. MATERIALS AND METHODS: In a prospective study 85 women with lower urinary tract symptoms underwent clinical evaluation, including physical examination, voiding cystourethrography, endoscopy, flow rate and post-void residual volume measurement. A pressure flow study was performed 15 days later. The pressure flow study parameters were maximum flow, post-void residual volume, detrusor pressure at maximum flow, vesical pressure at maximum flow, area under the curve of detrusor pressure during voiding and area under the curve of detrusor pressure during voiding adjusted for voided volume. After considering the clinical evaluation 2 urologists classified the patients into 3 groups, namely unobstructed, equivocal and obstructed, as the traditional classification. Linear discriminant analysis was then performed using the traditional classification and pressure flow study data. RESULTS: Mean patient age was 55 years (range 18 to 83). According to the traditional classification there were 36 unobstructed, 28 equivocal and 21 obstructed cases. Significant differences were noted in all pressure flow study parameters (analysis of variance p <0.05). Linear discriminant analysis showed that area under the curve of detrusor pressure during voiding adjusted for voided volume was the most statistically discriminating parameter. Of the cases 86%, 36% and 57% were identically categorized by the traditional and area under the curve of detrusor pressure during voiding adjusted for voided volume parameter classifications in the unobstructed, equivocal and obstructed groups, respectively. The other pressure flow study parameters showed less satisfactory results. CONCLUSIONS: Area under the curve of detrusor pressure during voiding adjusted for voided volume appears to be the most discriminating urodynamic parameter of female bladder outlet obstruction. Other studies are needed to test the reliability and validity of this new parameter.     

A statistical study of the effects of urethral instrumentation on urine flow in women

Data were obtained from a retrospective review of the records of 125 women who had undergone full urodynamic studies for a variety of clinical indications, to determine whether urethral instrumentation has an adverse effect on the parameters of urine flow in women. All patients had an initial urine flow study with a spontaneous void of at least 100 ml, after which they were catheterized to measure the postvoid residual urine. All patients then underwent urethral pressure studies, complex filling cystometry, pressure-flow voiding studies and urethrocystoscopy, after which they underwent another spontaneous non-instrumented urine flow study. Peak and mean flow rates were analysed statistically by blocked analysis of variance. The data were corrected for the effects of the volume voided by converting the flow rates into a nomogram percentile ranking using a computer program.Statistical analysis indicated that peak flow rates increased from an average of 21.7 ml/s (SD±10.8 ml/s) before instrumentation to 24.3 ml/s (SD±10.5 ml/s) after instrumentation (P=0.0045). Mean flow rates also increased from 12.0 ml/s (SD±7.3 ml/s) before instrumentation to 13.3 ml/s (SD±7.3 ml/s) after instrumentation (P=0.0365). However, when these data were corrected for the effects of the volume voided, both the average peak nomogram percentile and the average mean nomogram percentiles were reduced, from 29.1% to 24.2% for the peak flow rate (P=0.0426) and from 32% to 27.9% for the mean flow rate (P=0.1019).The corrected data indicate that both peak and mean flow rates are reduced in women following urethral instrumentation. The reduction in flow for peak flow rates is statistically significant. The reduction in mean flow rates did not reach this level of significance. This must be kept in mind when female patients are being evaluated for possible voiding disorders. Further prospective studies of the effect of urethral instrumentation on urine flow in women would seem to be indicated.     

Tubularized incised plate repair: functional outcome after intermediate followup

PURPOSE: We describe the functional outcome following tubularized incised plate repair of hypospadias in toilet trained children after an intermediate followup. MATERIALS AND METHODS: Children were included in this study only if they were toilet trained and had flow rate data not less than 6 months after primary tubularized incised plate hypospadias repair or 2 months after any secondary procedure to correct complications. Uroflow data (peak flow, voided volume and post-void residuals) were analyzed and plotted on previously determined age-volume dependent nomograms. RESULTS: Of the 48 boys 39 required no secondary procedures, while 9 secondary fistula closures were performed in 2, meatotomy in 2 and dilation in 5. After either primary (26) or secondary (7) procedures 33 of the 48 patients (68.7%) had normal peak flow rate and 15 (31.3%) had low peak flow rate. Of the 48 patients 46 had post-void residual urine less than 10% of voided volume. CONCLUSIONS: Most children will void efficiently with no straining and no post-void residual (1/2) to 4 years after tubularized incised plate hypospadias repair. Of our patients 68.7% have normal peak flow rate. Intermediate followup of larger series and followup at puberty are recommended to resolve the debate concerning the long-term functional outcome of tubularized incised plate hypospadias repair.     

Reference values and prediction equations for normal lung function in a non-smoking white urban population.

Prediction equations for normal lung function have been derived from tests on 179 healthy, non-smoking, white urban dwellers. The subjects, 96 women (height 1.46-1.77 m) and 83 men (height 1.61-1.96 m) aged 18-86 years, underwent measurements of spirometric flow and volume, multi-breath helium dilution lung volumes, and single breath carbon monoxide transfer factor and the single breath nitrogen washout test. Regression analysis using height, age, and weight as independent variables was used to provide predicted values for both sexes. Correlation coefficients were similar to those found in previous studies but normal ranges for spirometic measurements were narrower than in many previous studies, and spirometric flow and volume measurements were higher than those obtained in studies that included cigarette smokers, reflecting our more stringent criteria for selecting subjects and the newer standardised technical methods adopted. Multi-breath helium dilution values for total lung capacity were similar to those found in previous studies but the inspiratory vital capacity was larger and the residual volume reduced. Values for carbon monoxide transfer factor and the single breath nitrogen washout did not differ significantly from existing values. A complete set of lung function reference values and prediction equations for both sexes has been derived from a single population. The exclusion of cigarette smokers and subjects with respiratory symptoms has produced values that should have a greater sensitivity in the detection of mild lung disease.     

Factors causing differences in voiding parameters between conventional and ambulatory urodynamics

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. Received: 23 August 1999 / Accepted: 16 December 1999     

Detrusor pressure uroflowmetry studies in women: effect of a 7Fr transurethral catheter

PURPOSE: We evaluated whether a 7Fr transurethral catheter affects urinary flow in women undergoing pressure flow studies for voiding symptoms. MATERIALS AND METHODS: We reviewed a urodynamic database of 600 consecutive women referred for the evaluation of voiding symptoms. Before urodynamics all patients voided privately using a standard toilet and free flow was recorded. Urodynamics were performed using a 7Fr double lumen transurethral catheter. At functional bladder capacity patients were asked to void in the sitting position and pressure flow studies were performed. All uroflowmetry tracings were inspected and analyzed manually. Only patients who voided similar volumes varying by less than 20% on the free and pressure flow studies were assessed. Free and pressure flow parameters were compared according to voided volume category, main urodynamic diagnosis, uroflowmetry pattern and pre-void bladder volume. RESULTS: A similar volume was voided on the free and pressure flow studies of 100 women. In each voided volume category and urodynamic diagnosis pressure flow parameters were significantly different from the equivalent free flow parameters in all but 4 cases. Specifically the maximum flow rate was significantly less and flow time was significantly longer on pressure versus free flow studies (each p <0.01). An intermittent flow pattern was more common on pressure than in free flow measurements (43% versus 9%). CONCLUSIONS: A 7Fr transurethral catheter may adversely affect uroflowmetry parameters in women undergoing pressure flow studies for lower urinary tract symptoms. This finding may have further clinical implications regarding the interpretation of these parameters as well as establishment of an accurate diagnosis.     

Urinary flow rate in benign prostatic hypertrophy.

Multiple urinary flow measurements were recorded on 12 men without bladder outlet obstruction, ten men with a clinically doubtful diagnosis of bladder outlet obstruction due to benign prostatic hypertrophy, 29 men with a proven clinical diagnosis of bladder outlet obstruction due to benign prostatic hypertrophy and eight men before and after prostatic surgery. All were over 50 years of age. Mean peak flow rates for non-obstructed men varied from 11.8 to 35.0 ml per second and the minimum threshold for mean peak flow rate in these subjects was 15.0 ml per second for voided volumes of 200 ml and above. The vast majority of subjects with obstruction had mean peak flow rates below 15 ml per second. Mean peak flow rates reverted to normal after prostatic surgery. Our findings justify the use of multiple determinations of peak flow rate as a routine screening examination in subjects who may have bladder outlet obstruction due to benign prostatic hypertrophy.     

Gender differences in 24-hour urinary diaries of asymptomatic North American adults

PURPOSE: Two previously published studies from our center have described the urinary habits of asymptomatic men (284) and women (300) as revealed by 24-hour urinary diaries. Those gender specific studies found that urinary diary variables are affected by age and race. By comparing the data from those studies we determined the effect of gender on voiding habits. MATERIALS AND METHODS: In this secondary analysis we matched each female urinary diary to that of a male of similar age and race. Diary variables were compared using paired sign tests with results considered significant at the 5% level. RESULTS: A total of 141 matched pairs were studied. The population age ranged from 18 to 68 years and was racially diverse (56% black, 31% white, 7% Hispanic and 6% Asian). Men had higher total fluid intake and mean voided volume than women (p <0.001 and 0.04, respectively). Women voided more frequently than men (p = 0.006) and had more voids per liter of fluid intake (p <0.001). No gender differences were found for body mass index, nighttime or daytime diuresis rates, total urine volume, maximum voided volume or rates of nocturia. CONCLUSIONS: This analysis suggests that there are significant gender effects on 24-hour diary variables, with females tending to void more often and at lower mean volumes. The results of our study may be useful in the design of research studies or for patient counseling.