Low Urine Flow Research Articles

Ritenzione urinaria acuta in giovani donne con sindrome uretrale. Protocollo diagnostico e terapeutico

The Urethral Syndrome is defined as lower urinary symptoms in women in the absence of bladder bacteriuria. Symptoms include straining to void, urgency frequency, hesitation, incontinence, retention and subpubic pain. In females affected by urethral syndrome some authors have found histological degeneration and urodynamic alterations, such as significantly higher than normal maximum urethral closure pressure, low urinary flow rates. The authors studied 5 women with urethral syndrome, and acute or chronic urinary retention. A personal therapeutic approach is presented.

The effects of a converting enzyme inhibitor (captopril) and angiotensin II on fetal renal function.

1. Renal function was studied in chronically catheterized fetal sheep (119-128 days gestation), before and during treatment of the ewe with the angiotensin converting enzyme (ACE) inhibitor, captopril, which crosses the placenta and blocks the fetal renin angiotensin system. 2. An i.v. dose of 15 mg (about 319 micrograms kg-1) of captopril to salt-replete ewes followed by an infusion to the ewe of 6 mg h-1 (about 128 micrograms kg-1 h-1) caused a fall in fetal arterial pressure (P < 0.01), and a rise in fetal renal blood flow (RBF) from 67.9 +/- 5.6 to 84.9 +/- 8.3 ml min-1 (mean +/- s.e. mean) (P < 0.05). Renal vascular resistance and glomerular filtration rate (GFR) fell (P < 0.01); fetal urine flow (P < 0.01); fetal urine flow (P < 0.01) and sodium excretion declined (P < 0.05). 3. Ewes were treated for the next 2 days with 15 mg captopril twice daily. On the 4th day, 15 mg was given to the ewe and fetal renal function studied for 2 h during the infusion of captopril (6 mg h-1) to the ewe. Of the 9 surviving fetuses, 3 were anuric and 3 had low urine flow rates. When 6 micrograms kg-1 h-1 of angiotensin II was infused directly into the fetus RBF fell from 69 +/- 10.1 ml min-1 to 31 +/- 13.9 ml min-1, GFR rose (P < 0.05) and urine flow (P < 0.01) and sodium excretion increased in all fetuses. 4. It is concluded that the small fall in fetal arterial pressure partly contributed to the fall in fetal GFR but in addition, efferent arteriolar tone fell so that the filtration pressure fell further. Thus maintenance of fetal renal function depends on the integrity of the fetal renin angiotensin system. These findings explain why use of ACE inhibitors in human pregnancy is associated with neonatal anuria.

How reliable is a single measurement of urinary flow in the diagnosis of obstruction in benign prostatic hyperplasia?

Twenty-six elderly patients with obstructive symptomatology and an initial low peak urinary flow rate (< 15 ml/s) were observed for 6 to 12 months. Repeated assessments were made of flow rates and residual volumes. Within patients variation of the maximal urinary flow was significant; the standard deviation (SD) varied from 0.8 to 5.5 ml/s. The SD varied with the mean peak flow rates and this suggests that the precision of a single determination of a patient's peak flow is inversely related to the peak flow itself. In all, 333 determinations of peak flow were obtained. Only 80% were below 2 SD of the mean Siroky nomogram. Multiple determinations were used to estimate the sensitivity rate for each patient, i.e. the proportion of peak flows that were less than 2 SD below the mean of Siroky's nomogram. The average sensitivity for all of the flow values was 0.813 when applied to voided volumes and increased only slightly to 0.838 when applied to total bladder volume. Given a prevalence of 0.70 of obstruction ascribed to benign prostatic hyperplasia (BPH) among elderly men, the positive predictive value of an abnormally low peak flow was 0.97. A single low peak flow based on assessment of voided volume may serve as an almost sure indication of obstruction. If a patient has a single normal peak flow rate, he still has a 0.31 probability of having evidence of obstruction in his following uroflow determinations. Using total bladder volume does not make a difference in most patients and is not worth the effort and discomfort. The only patients who require accurate residual measurements are those with a normal uroflow but clear-cut obstructive symptomatology or with borderline peak flow. The results of this study are relevant to everyday clinical practice and to the evaluation of studies on alternatives to surgery in BPH.

Intra-operative blood pressure control by prostaglandin E1 in patients with hypertension and ischemic heart disease--a multi-center study.

The purpose of this multi-center study was to evaluate the efficacy and safety of prostaglandin E1 (PGE1) administration in achieving deliberate hypotension and in treating intraoperative hypertension for patients with a history of hypertension and ischemic heart disease. PGE1 (0.08 microg.kg(-1).min(-1)) decreased systolic blood pressure from 125 +/- 29 to 106 +/- 22 mmHg (mean +/- SD) in the deliberate hypotension group (n = 158) and from 155 +/- 34 to 125 +/- 32 mmHg in the antihypertension group (n = 55). The heart rate significantly increased from 80 +/- 15 to 85 +/- 18 beats.min(-1) in the deliberate hypotension group, but was not significantly altered in the antihypertension group. The time required to obtain the desired level of blood pressure was approximately 20 min in the deliberate hypotension group. When the infusion was stopped, blood pressure returned approximately to the preinfusion level within about 20 min. No rebound hypertension was observed. PGE1 significantly increased the urine flow in patients who had a low urine flow before PGE1 infusion. Thirteen out of 213 patients (5.6%) had side effects such as excessive hypotension (1%), phlebitis (3%), and unexpected tachycardia (1%), which were alleviated gradually after discontinuation of PGE1 infusion. No dysarrhythmia and further ST segment changes in the electrocardiograms were observed. These findings suggest that PGE1 can be safely used to control arterial blood pressure during surgery in patients having preoperative hypertension and ischemic heart disease.

Detrusor contraction strength in men undergoing prostatectomy

Elective prostatectomy is a frequently performed operation but the outcome may not always be satisfactory. This is probably because a significant number of men, despite subjective symptoms, are not urodynamically obstructed before operation and the preoperative assessment of obstruction is not easy using conventional urodynamic criteria. We have calculated detrusor contraction strength (WF) in men before and after prostatectomy. Our aim was to determine its relationship with symptomatic and urodynamic findings before and after prostatectomy and whether it was associated with clinical outcome. One hundred and twenty nine men listed for operation because of symptoms and low urinary flow rates were studied by means of urodynamic investigation and symptom scoring both before and 6 months after prostatectomy. A significant association was found between persistent obstructive symptoms after operation and a low WF before operation (P = 0.01), suggesting that weak detrusor function before operation was the cause of persistent symptoms afterwards. A significant correlation was also found between a high pre-operative WF and a high post-operative urinary flow rate; (P = 0.003); men with high detrusor power achieving the better flow rates after operation. Despite this relationship, the overall subjective clinical outcome was not strongly associated with WF and WF was no better than simple measurement of voiding pressure in predicting outcome in a multivariate analysis. The measurement of detrusor contraction strength provides some insight into the relationship between bladder function and clinical outcome after prostatectomy, but we have found it unable to predict outcome for the individual patient.

Perturbation of paracetamol urinary metabolic ratios by urine flow rate.

The effects of high and low urine flow rates on the urinary metabolic ratios for paracetamol glucuronidation, sulphation and oxidation were determined at steady-state in seven healthy young adult volunteers. Metabolic partial clearances were unaffected by urine flow rate, but individual paracetamol metabolic ratios varied 2.5- to 3.2-fold over a 7.4-fold range of urine flow rates (0.81-6.00 ml min-1). The change in metabolic ratios was due entirely to a 2.5-fold change in renal clearance of unchanged paracetamol. These data emphasise the limitations of the metabolic ratio as a measure of intrinsic clearance for compounds which undergo some degree of tubular reabsorption.

Hyperkalemia in very low birth weight infants

To assess the frequency and pathogenesis of hyperkalemia in the very low birth weight infant. Infants who weighed less than 1000 gm at birth were prospectively entered into the study within 12 hours of birth. Potential risk factors for hyperkalemia were assessed. Body weight, fluid and electrolyte balance, serum levels of sodium and potassium, creatinine clearance, fractional sodium excretion, and urine sodium/potassium ratio were measured every 8 hours for 72 hours. Measurements of plasma renin, serum aldosterone, and plasma atrial natriuretic factor were made at study entry and repeated when hyperkalemia (serum potassium greater than 6.5 mmol/L) occurred or at 72 hours. Infants in whom hyperkalemia developed were compared with those in whom it did not. Thirty-one infants completed the study; hyperkalemia developed in 16 (51.6%). The only difference in the occurrence of perinatal complications was the more frequent occurrence of pH less than 7.20 in infants with subsequent development of hyperkalemia. Creatinine clearance, urine output, and potassium excretion were significantly lower in the hyperkalemia group during the first 24 hours. Serum potassium concentration at 24 hours was inversely related to urine output in the prior 24 hours. Fractional sodium excretion, urine sodium/potassium ratio, and levels of renin, aldosterone, and atrial natriuretic factor did not differ between groups. Hyperkalemia is a frequent complication in very low birth weight infants. Infants with low urinary flow rates during the first few hours after birth are at greatest risk for the development of hyperkalemia.

Renal response to volume depletion and expansion in Milan hypertensive rats.

In previous studies on Milan hypertensive (MHS) rats, we found an impaired tubuloglomerular feedback (TGF) response before, during and after development of hypertension. In the present study MHS rats and rats of the Milan normotensive strain (MNS) were investigated after 24 hours of volume depletion (VD) and subsequently after 5% isotonic volume expansion (VE) with respect to whole kidney function, interstitial hydrostatic (P(int)) and oncotic (IIint) pressures, stop-flow pressure characteristics of TGF and changes in early proximal flow rate in response to increased loop of Henle flow. MHS rats had higher mean arterial blood pressure (Pa) than MNS rats (129 vs. 101 mmHg) both after VD and after subsequent VE. No difference in glomerular filtration rate (GFR) was found. Both strains had a low urine flow rate (approximately 1.5 microliters min-1) during VD, which increased fourfold after VE. The interstitium was significantly more dehydrated in MHS, as indicated by a more negative net interstitial pressure (P(int)-IIint than in MNS (-1.3 +/- 0.3 vs. +/- 0.0 +/- 0.5 mmHg) after VE. The TGF mechanism was more activated in MHS during volume depletion, as indicated by a larger drop in stop-flow pressure (Psf) in response to loop of Henle perfusion (7.1 +/- 0.7 vs. 4.7 +/- 0.2 mmHg, P less than 0.05). However, during VD the loop of Henle flow that elicited half maximal response in Psf, the turning point (TP), was equally low in MHS and MNS (13.5 +/- 0.6 and 14.3 +/- 0.4, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of the Interaction of Lithium and Alprazolam

A potential pharmacokinetic interaction between lithium and alprazolam was studied in 10 normal subjects. Pharmacokinetic parameters were determined from the following regimens: single-dose alprazolam, multiple-dose lithium, and multiple-dose alprazolam with lithium. Steady-state alprazolam clearance during multiple dosing with lithium was not different from that with the single dose of alprazolam. Lithium renal clearance decreased when it was coadministered with alprazolam (31.2 vs. 22.4 ml/minute, p less than 0.05). There was a small but significant increase in the steady-state area under the curve for lithium in the presence of alprazolam (10.3 vs. 11.1 mEq/hour/liter). The small increase in the serum lithium concentrations and decrease in lithium renal clearance was probably the result of lower urine flow rates (1.46 vs. 0.98 ml/minute, p less than 0.05) with the combination of the drugs. This is supported by a weak but significant linear relationship between urine flow rates and lithium renal clearance (N = 57, r = 0.353, p = 0.007). The percent of daily lithium dose recovered at steady-state from the 24-hour urine collection decreased significantly from 93.6% to 78.2% in the presence of alprazolam. This suggests that alprazolam may decrease lithium absorption. The results of this study do not support a definitive interaction of lithium and alprazolam and there is little clinical significance to the small rise in serum lithium concentrations.

Visual Analogue Scales Distinguish between Low Urinary Flow Rates due to Impaired Detrusor Contractility and those due to Bladder Outflow Obstruction

In patients with symptoms suggestive of bladder outflow obstruction and a free flow rate less than 12 ml/s a visual analogue scale was used to measure the response to the question "Compared to 5 years ago, how thick is your stream when you pass urine?". The visual analogue scale compared favourably with cystometry in distinguishing between low flow rates resulting from impaired detrusor contractility and low flow rates due to bladder outflow obstruction. A visual analogue scale may serve to alert the surgeon to the presence of impaired detrusor contractility and the need for a fuller urodynamic assessment in patients with a low urinary flow rate prior to consideration for prostatectomy.

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.

Practical Management of Urinary Incontinence

A comprehensive evaluation of incontinence using office-based techniques may discover reversible problems such as delirium, urinary infections, vaginitis, depression, drug effects, endocrinologic causes, immobility, or impaction. Treatment of these causes may alleviate incontinence. Bedside urodynamics are a sensitive, specific, and useful office-based technique that can identify detrusor instability, overflow incontinence, or stress incontinence. Low urinary flow rate, difficulty with catheterization, slow bladder filling or severe urgency, bladder capacity over 600 ml, and post-void residual over 150 ml need referral. Patients with hematuria, recurrent infections, recent surgery or pelvic irradiation, and pelvic or prostatic masses also need further evaluation. A number of medical and behavioral therapies are available for stress incontinence and detrusor instability that can substantially reduce incontinence, but most patients with overflow have more complicated problems requiring further evaluation, surgery, or long-term bladder drainage.

Outcome of elective prostatectomy.

To determine the symptomatic and urodynamic outcome of elective prostatectomy and to establish whether the outcome is influenced or can be predicted by preoperative urodynamic measurements. Prospective non-randomised study with follow up at a mean of 11 months after operation. Most men were assessed jointly by a urologist and a general practitioner. Department of urology in a teaching hospital serving a large district population. 253 Men listed for elective prostatectomy because of symptoms and low urinary flow rates (less than 15 ml/s) and excluding those already on a waiting list or with acute urinary retention, clinically apparent prostatic cancer, and neurological or cerebrovascular disease; 217 (86%) were followed up. Elective prostatectomy. Classification on the basis of relief of symptoms assessed by patients and urologist and general practitioner and of symptom scores obtained by questionnaire. Of the 217 men followed up, 171 (79%) had a satisfactory subjective review and 155 (72%) had a satisfactory review and also low symptom scores. An unsatisfactory outcome was associated with preoperative symptoms of urge incontinence, small prostatic size and resected weight, low voiding pressures, and low urethral resistance. Preoperative maximum urinary flow rates did not predict outcome. Men with poor outcome could be classified into two groups: those with irritative symptoms who were more likely before operation to have had urge incontinence and detrusor instability and men with symptoms of poor urinary flow who were more likely before operation to have had a small prostate, low voiding pressures, and low urethral resistance. In patients in the second group flow rates or voiding pressures improved little after operation. Men with stable detrusors and either low urethral resistance or low voiding pressures were less likely to do well after prostatectomy, but despite these associations preoperative urodynamic measurements were unable to predict outcome accurately. Prostatectomy was satisfactory in relieving symptoms and improving urodynamic measurements in most men, but even in those with classic symptoms and low urinary flow rates a substantial minority experienced little improvement afterwards and urodynamic measurements did not accurately predict outcome in individual patients.

Evaluation of intermittent drainage of the renal pelvis as seen in the isotope renogram.

Intermittent drainage (ID) of the renal pelvis is probably due to episodes of aperistalsis in the pelvo-calyceal system. The incidence of ID in adult patients referred for renography for various nephro-urological conditions was found to be 4.5%. Presence of ID was not related to sex or age but more common at a low urine flow. It was then usually bilateral and interpreted as a normal phenomenon. If the urine flow at the renographic examination exceeded 2 ml min-1, ID was typically unilateral and there was often a history of obstructive uropathy and dilatation of the renal pelvis. However, there were no signs of obstruction or flank pains in connection with the recording of ID and follow-up studies did not disclose any deterioration of renal function. It is concluded that ID seen at renography during diuresis should not be regarded as evidence of obstruction of pelvic outflow but merely as an indication of a dilated upper urinary tract.

Influence of renal failure on urodynamic, cystoscopic and radiologic evaluations of the lower urinary tract: Implications for the pre‐renal transplant evaluation

AbstractA retrospective analysis of 175 consecutive renal transplant patients who underwent extensive urodynamic evaluation and cystoscopy was performed. Urodynamic abnormalities were few, but general trends appeared. Pretransplant patients tended to have small‐capacity bladders (mean 280 cc) and low urine flow rates (mean 7 cc/sec). The flow rates returned to normal after transplantation regardless of preoperative urine volumes. Cystoscopy failed to demonstrate anatomical abnormalities not discovered on preoperative voiding cystourethrography, and no patient was found to have a lower urinary tract malignancy. A history and physical examination, urinalysis, urine culture, and voiding cystourethrogram constitute an adequate urologic screening evaluation for most renal transplant candidates. Although some patients require cystoscopy and urodynamic evaluation, we have abandoned the “routine” use of these studies.

Atrial natriuretic peptide, right atrial pressure, and sodium excretion rate in the rat.

This study examined the relationship between right atrial pressure (RAP), urine flow rate, sodium excretion rate, and plasma atrial natriuretic peptide (ANP) levels after an acute Ringer expansion. Two groups of rats had their RAP monitored and balloon catheters placed in their thoracic inferior venae cavae. In one group the balloon remained deflated, and in the second group the balloon was inflated during the volume expansion in an attempt to prevent the rise in RAP. The peak RAP was 7.3 +/- 0.8 mmHg when the balloon remained deflated and 3.5 +/- 0.6 mmHg in the group with the balloon catheter inflated (P less than 0.005). The corresponding peak ANP levels were 682 +/- 140 and 223 +/- 40 pg/ml. There was a significant correlation between the peak RAP and ANP levels (r = 0.754; P less than 0.05). The inflation of the balloon catheter significantly decreased the urine flow rate and the urine sodium excretion rate. A final group of animals had 200 microliters of rabbit serum containing antibody to ANP infused before the volume expansion. The antibody-treated animals had significantly lower urine flow and sodium excretion rates than nonantibody-treated control rats. We conclude that ANP is one of the factors which allows the rat to excrete an acute Ringer expansion.

The composition of four-hour urine samples from patients with calcium oxalate stone disease.

Urine collected during a 24-h period between 06.00 and 10.00 h from 25 patients with recurrent CaOx stone disease was analysed with respect to calcium, oxalate, magnesium, citrate and creatinine. Urinary excretion of oxalate in relation to creatinine was slightly higher in 24-h urine but the correlation between 24-h and 4-h values was good. Good correlations were also recorded for calcium and citrate, whereas a more variable result was obtained for magnesium. In terms of the risk of forming a supersaturated urine (CaOx risk index), a good correlation was observed between 24-h and 4-h urine samples, although the highest values were found in 24-h urine. As a result of a low mean urine flow between 06.00 and 10.00 h, the highest supersaturation in terms of the AP (CaOx) index was observed in these samples. When the risk of calcium oxalate crystallisation (CaOx-CR) was determined by means of the increment in oxalate concentration required for precipitation of CaOx, 7 of 11 samples had the highest values in the 4-h urine. Samples collected during a 4-h period might thus be useful in the evaluation and follow-up of CaOx stone formers and further studies will show to what extent they can replace 24-h urine collections.

Hibernation “trigger” from hibernating woodchucks ( Marmota monax) induces physiological alterations and opiate-like responses in the primate ( Macacca mulatta)

1. 1. Hibernation “trigger” (HT) from the blood of hibernating wood-chucks infused peripherally, or into the cerebral ventricle of the conscious monkey induces hypotherma, aphagia, bradycardia, reduction of creatine clearance, lower urine flow, and opiate -like behavioural modification. 2. 2. Naloxone and naltrexone, opiate antagonists, either reverse or retard these alterations. 3. 3. The “trigger” (HT) appears to be an endogenous opioid-like peptide unique to the hibernator and capable of inducing hibernation. 4. 4. Receptor sites in the brain of the primate (a non-hibernator) do respond to the “trigger” molecule and as a result, depression of physiology and behaviour occur.

Cutaneous Ion Transport in the Freshwater Teleost Synbranchus marmoratus

The gills of Synbranchus marmoratus become isolated from water for long periods of time while this fish breaths air or resides in moist burrows. In order to evaluate how interruptions in gill/water contact affect ionic regulation, we have undertaken urine collections and measurements of net and unidirectional sodium fluxes on intact, conscious fish. Comparative ionic flux measurements were made on the lungfishes Lepidosiren paradoxa and Protopterus spp. All three species demonstrated Na⁺ influx rates that are low for fish and freshwater vertebrates in general. Synbranchus marmoratus has an affinity ($K_{m}$) of 0.45 mM and a capacity ($J_{max}$) of 41.1 μEq/kg h⁻±, suggesting a relatively low-affinity, low-capacity ion transport system. The transepithelial potential difference measured between the bath and extracellular fluid was -7 mV (inside reference); thus the fluxes could not be accounted for by passive transport mechanisms (Ussing criterion). Synbranchus marmoratus has both a low urine flow (1.8 ml/...

Fluid conservation in athletes: responses to water intake, supine posture, and immersion.

The roles of antidiuretic hormone (ADH) and aldosterone in the elicited diuretic responses of trained and untrained men to seated, supine, and head-out water immersed conditions were studied. Volunteers were comprised of groups of six untrained individuals, six trained swimmers, and six trained runners. Each subject underwent three protocols, six hours in a seated position, supine position, or immersion (35 degrees C water). The last two protocols were preceded and followed by 1 h of seated position. After 10 h of fasting, 0.5% body wt of water was drunk. One hour later the trained groups had higher urine osmolalities (P less than 0.05) and urinary excretion rates of ADH (P less than 0.05) and lower urine flow rates (P less than 0.05) than untrained subjects. Throughout the sitting protocol, urinary ADH was also higher in both trained groups (P less than 0.05). Both supine posture and immersion resulted in significant decreases in urinary ADH in the untrained subjects (P less than 0.05) but no changes wer noted in swimmers and only during the second hour of immersion in the runners (P less than 0.05). The natriuresis and kaliuresis were greater during immersion than in the supine position but plasma renin activity, measured only in trained groups, and plasma aldosterone, measured in the untrained group, were decreased similarly with both protocols. The increases in urinary sodium excretion and urine flow rate were lower in trained than untrained subjects during the supine and immersion protocols (P less than 0.05). The data are compatible with an increased osmotic but decreased volume sensitivity of ADH control in trained men.