Age related flow rate nomograms in a normal pediatric population

Uroflow studies in a normal pediatric population were analysed statistically. Single studies for 511 subjects (272 boys and 239 girls) were reviewed. Nomograms relating peak flow to volume voided and age 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. The mean values of peak flow rate increased with volume voided in both sexes and also with age in the male population. Different sets of nomograms, which are necessary for daily clinical evaluation, are given. They define the normal values in the normal population.     

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.     

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.     

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.     

Micturition and uroflowmetric analysis of adult females

Voiding parameters on the Uroflow Diagnostic Interpretation (UDI) were analysed in relation to the voided volume in 58 micturitions of 36 healthy adult females. The maximum flow rate (Qmax) and the mean flow rate during central 90% of the voided volume (QM90) increased linearly up to the voided volume of 400 ml. The voiding time (T100) took a value within a certain range independently of the voided volume from 100 to 400 ml and never exceeded 21 seconds in all micturitions. Voiding time for the central 90% of the voided volume (T90), time to Qmax (TQmax) and time from Qmax to 95% of the voided volume (Tdesc) were independent of the volume voided. The maximum rate of increase of flow rate (dQ/dT max) and the estimated bladder wall contraction velocity at 40 ml bladder contents (dL/dT 40) showed a tendency to increase depending on the volume voided. T100 showed a prolongation in 84.0% of 25 micturitions in 20 neurogenic bladder patients and in 66.7% of 27 in 21 chronic cystitis patients, always accompanied by a prolongation of T90. No other parameters were clearly different between healthy women and patients and/or between the two groups of patients. Voiding time is a useful parameter representing female micturition.     

Urine flow rates in male and female urodynamic patients compared with the Liverpool nomograms

The Liverpool male and female nomograms provide normal reference ranges for the maximum and average urine flow rates over a wide range of voided volumes. A known urine flow rate, in combination with the respective voided volume (and in men the age), can be converted into an equivalent centile ranking, using the equation for the relevant nomogram. Centile rankings allow the urine flow rates of specific male and female populations to be compared. The maximum and average urine flow rates of urodynamic patients (504 consecutive male and 168 consecutive female) were converted into centile rankings. These centile rankings were then compared with the respective urodynamic diagnoses. The median centile rankings for their maximum and average urine flow rates were 21 and 11 (male) respectively and 31 and 18 (female) (vs 50 for the normal populations). The low urine flow rates applied to all diagnostic groups, including those symptomatic men and women who were found to be urodynamically normal. Low urine flow rates may be one of a number of subtle manifestations of urological disease in these patients. Men with obstruction and women with voiding difficulties had the lowest urine flow rates. The 25th centile (men) and the 10th centile (women) appeared to be most appropriate lower limits of normality for both urine flow rates to identify those men more likely to be obstructed and those women at higher risk of voiding difficulties. Men and women with detrusor instability had the highest urine flow rates. Detrusor instability was present in 71% of men with centile rankings for the maximum urine flow rate over 50; 50% of women whose maximum urine flow rate centiles were over 90 had detrusor instability.     

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.     

Voiding frequency in a sample of asymptomatic American men

PURPOSE: There are sparse published data concerning the urinary habits of asymptomatic American men. We studied those urinary habits, as revealed by a 24-hour voiding diary. MATERIALS AND METHODS: Men without lower urinary tract symptoms completed the International Prostate Symptom Score (I-PSS) and a 24-hour voiding diary. Demographic and diary data were analyzed using multivariate linear and logistic regression. RESULTS: A total of 284 asymptomatic males 18 to 66 years old returned interpretable diaries. Subjects voided a median of 7 times in 24 hours (range 2 to 21) with 95% voiding fewer than 12 times daily. Median 24-hour urine volume was 1,650 ml (range 290 to 6,840). Median fluid intake was 2,747 ml (range 500 to 10,520). Of the men 82 (29%) reported at least 1 nocturic episode. The 24-hour frequency was related to total urine volume (beta = 1.2, p <0.001) and total fluid intake (beta = 0.1, p <0.001), inversely related to mean voided volume (beta = -1.1, p <0.001) and lower in white men (beta = 0.1, p <0.02) but independent of age and body mass index. The probability of nocturia was highly related to the nighttime diuresis rate (beta = 15, p <0.001), inversely related to mean voided volume (beta = 1, p = 0.001) and less likely in white men. Median I-PSS was 2 (range 0 to 22). I-PSS increased with age, body mass index and total urinary frequency, and it was lower in white men. CONCLUSIONS: This study suggests that the threshold of 8 to define abnormal urinary frequency may not be correct since more than a third of our sample of asymptomatic men voided more than 8 times daily. It is probably inadvisable to apply a single set of normative values to all American men because of significant variability in regional climates and populations.     

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.     

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.     

Uroflowmetry in the puerperium

One hundred women underwent uroflowmetry once per day for the first 3 days after delivery, and the results compared to those of 53 nonpregnant controls in an effort to determine 1) whether urinary flow in the puerperium is different to that found without pregnancy, 2) whether uroflow parameters change as the puerperium progresses, and 3) which characteristics of a patient or her labour bear most influence upon the results of uroflowmetry. Urinary flow in the puerperium was seen to be different from that of the nonpregnant female in that mean flow rates were lower. In addition to this, voided volume, total flow time, and time to peak flow were all significantly increased on day 1, but were comparable on days 2 and 3. Other than for falling voided volumes, uroflow parameters did not alter significantly as the puerperium progressed. Correlation of the variables age, parity, baby weight, length of first and second stage, use of epidural and perineal suturing with the parameters of urinary flow failed to show any significant relationship. © 1993 Wiley-Liss, Inc.     

Variation in urinary flow according to voiding position in normal males.

Our objective was to study whether the urinary flow rate would vary according to voiding position. Twenty-one normal healthy male volunteers aged 24 to 40 years (mean, 29 years) were studied. The bed used was designed so that a hole could be opened at its center for voiding, and the bed could be bent at two points so that the subject could void in various positions. Urinary flow was measured with a portable uroflowmeter (P-Flow), which permits measuring urinary flow rate. Each subject assumed five voiding positions (standing, sitting, lateral, supine, and prone) in random order. Urinary flow was measured at least twice in each position to record a stable voiding. For voiding in the lateral position, subjects were instructed to void while bending the upper leg to keep an open angle between the legs. All subjects were also instructed to void without increasing abdominal pressure. Maximum flow rate was 20.7 +/- 6.59 mL/sec with voided volume of 262 +/- 77.8 mL in the lateral, 22.1 +/- 7.05 mLl/sec with voided volume of 309 +/- 130 mL in the supine, 25.0 +/- 8.25 mL/sec with voided volume of 287 +/- 122 mL in sitting, 27.1 +/- 8.89 mL/sec with voided volume of 263 +/- 102 mL in the standing, and 28.7 +/- 10.6 mL/sec with voided volume of 303 +/- 98 mL (mean +/- SD) in the prone positions. The maximum and mean urinary flow rates were greatest in the prone position. With regard to these parameters, significant differences were noted between the prone and lateral positions and between the prone and supine positions. In conclusions, the maximum urinary flow rate was highest in the prone position, followed by the standing, sitting, supine, and finally the lateral positions in normal males. Neurourol. Urodynam. 18:553-557, 1999.     

1024例儿童尿流率调查

目的 寻求长沙地区儿童尿流率正常值及其列线图。方法 对1024名正常儿童进行1048次尿流率检测。将所得资料按性别、年龄、体表面积、排尿量分组后进行统计学分析，并绘制出各组相应的列线图以阐明尿量、体表面积、平均尿流率、最大尿流率4者的相互关系。结果 正常儿童尿流率曲线为典型的钟形曲线。〈7岁男性儿童的最大尿流率随年龄增加而增加，年龄每增加1岁最大尿流率增加1．7ml／s，〉7岁者其最大尿流率同成年人相仿。〈9岁女性儿童的最大尿流率随年龄增加而增加，年龄每增加1岁最大尿流率增加1．2ml／s，〉9岁其最大尿流率同成年人相近。儿童最大尿流率、平均尿流率及排尿量均随体表面积增加而增加，同时，最大尿流率、平均尿流率也均随排尿量的增加而增加。结论 〈9岁的女童和〈7岁的男童最大尿流率的正常值有明显的年龄依从性。     

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).     

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.     

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.     

膀胱出口梗阻指数在评估良性前列腺增生症膀胱出口梗阻中的应用

目的 探讨膀胱出口梗阻指数(BOON)在评估前列腺增生患者膀胱出口梗阻(BOO)中的意义.方法 对临床有下尿路症状,怀疑存在因前列腺增生症(BPH)导致膀胱出口梗阻的76例患者,测定前列腺体积(经直肠),最大自由尿流率(Qmax)和平均排尿量,通过公式计算BOON=前列腺体积(cm3)-3×Qmax(ml/s)-0.2×平均排尿量(ml).同时对患者进行压力.流率测定,计算AG值和Schafer梗阻级别,与BOON对照,分析利用BOON评估膀胱出口梗阻的准确性.结果 将本组患者年龄、前列腺体积、最大尿流率、残余尿量及BOON值,以AG作为因变量,同AG进行多元线性回归分析.整体回归方程中R=0.542(P=0.000),其中BOON值同AG值相关性最强(P=0.000).18例BOON值>-10,此时利用BOON判断BOO的敏感性为31%,特异性为100%,取BOON>-20时,敏感性为42.4%,特异性为88.2%;取BOON>-30时,敏感性为66.1%,特异性为82.4%;而取BOON>-40时,敏感性为77.9%,其特异性为64.7%.取BOON值-30作为分界点,在不明显降低特异性的同时,能够更敏感的判断BOO,BOON数值越大,利用BOON判断膀胱出口梗阻的特异性越高.结论 通过测定前列腺体积,最大自由尿流率(Qmax)和平均排尿量计算膀胱出口梗阻指数,取BOON>-30为分界点,是预测前列腺增生症是否存在膀胱出口梗阻的一种简易、无创方法,具有较好的特异性和敏感性.     

Variability and circadian changes in home uroflowmetry in patients with benign prostatic hyperplasia compared to normal controls.

We evaluated the variability and circadian changes in consecutive measurements of home uroflowmetry in 32 patients with symptomatic benign prostatic hyperplasia (BPH) and 16 healthy men. In the BPH group 476 uroflow measurements were recorded during 24 to 72 hours (mean 14.9 measurements per patient), and the controls produced 100 flow recordings (mean 6.25 measurements per participant). Great variability between consecutive peak flow rates was observed in the BPH group, ranging from at least 1 standard deviation in 28 of 32 patients (87.5%) to at least 2 standard deviations in 15 of 32 (47%). In 21 of 32 patients (65.6%) the highest recorded peak flow rate was greater than, while the lowest peak flow rate was less than the -2 standard deviations plot in voiding nomograms. In the control group variability between consecutive voiding episodes also was marked, namely at least 1 standard deviation in 8 of 16 men (50.0%) and at least 2 standard deviations in 2 of 16 (12.5%). However, in none of the control men was any peak flow rate measurement less than the -2 standard deviations line. Circadian changes in diurnal and nocturnal measurements of voided volume, interval to maximal flow, flow time, peak flow rate and adjusted peak flow rate were recorded in the BPH group, providing a urodynamic support to a well known clinical observation.     

Measurement of urinary flow rate using ultrasound in young boys and infants

PURPOSE: We present a technique for measuring urinary flow rates with ultrasound in male infants and children. MATERIALS AND METHODS: Urinary flow rate was measured simultaneously by an ultrasound probe placed around the base of the penis and by a funnel with a rotating disk at the bottom in 30 boys with a mean age of 6.7 years (range 4.5 to 10.5), and by ultrasound in 8 infants with a mean age of 10 months (range 1 to 28). Voided volume was measured with a graded cylinder or calculated from the weight change of diapers in infants. Ultrasound and rotating disk maximum flow rates were calculated. The ultrasound signal was calibrated by comparing the collected voided volume to the area under the curve for that void. The volume calculated from the rotating disk flow rate curve was also compared with the collected volume. RESULTS: Both methods yielded similar flow curves. However, ultrasound maximum flow rate significantly exceeded rotating disk maximum flow rate (13 +/- 6 ml. per second, range 5 to 22 versus 10 +/- 4 ml. per second, range 4 to 21, t test p <0.001). The underestimation of the flow rate by the rotating disk method may have been due to adherence of urine to the funnel wall. Rotating disk maximum flow rate was lower and voided volume was underestimated by up to 50% (average 15 +/- 2%) in 21 cases. Ultrasound maximum flow rate averaged 6 +/- 3 ml. per second (range 3 to 11.6 [oldest infant]) in the 8 infants. CONCLUSIONS: Urinary flow rates can be measured accurately using ultrasound in boys who produce small volumes and/or who are not toilet trained and also in infants. In future studies ultrasound will be applied to subsets of male infants with bladder dysfunction.