Mean Effective Renal Plasma Flow Research Articles

Renal function and adaptive changes in patients after radical or partial nephrectomy

IntroductionRenal function after renal surgery depends on the volume of renal parenchyma loss and improves in the postoperative period. However, the knowledge on kidney function after radical (RN) and partial (PN) nephrectomy is still insufficient. The aim of this study is to analyze the global renal function and compensatory hyperfunction of the non-operated kidney in patients with renal cancer after RN or PN. MethodsFifty-one patients of mean age 62.2 years with renal cancer were included. Thirty-three RN and eighteen PN were performed. We measured creatinine serum concentrations, and we estimated glomerular filtration rate (eGFR) preoperatively and postoperatively at two time intervals: 3 and 12 months after surgery. Additionally, we assessed effective renal plasma flow (ERPF) in dynamic scintigraphy preoperatively and 12 months after surgery. ResultAt the baseline, all mean measured values were comparable in RN and PN groups (P > 0.05). Three months after surgery, creatinine level increased in both groups, more remarkably in RN group (128 mmol/l vs. 95 mmol/l; P < 0.05), while eGFR diminished (47 ml/min/1.73 m2 vs. 70 ml/min/1.73 m2; P < 0.05). Similar biochemical values were observed 12 months after surgery. The mean ERPF of the non-operated kidney 12 months after surgery in RN and PN groups increased by 3.8% (232 ml/min) and 0.1% (200 ml/min), respectively (P > 0.05). The mean ERPF of the operated kidney in PN group decreased by 24.7% (149 ml/min). ConclusionThe deterioration of renal function after partial nephrectomy is nearly insignificant clinically. In 1-year postoperative observation, the renal function does not improve. This causes potential compensatory mechanisms to be insufficient.

Compensatory Changes in the Function of the Remaining Kidney Immediately after Unilateral Nephrectomy in Sheep

Live kidney donation is an established form of organ donation but carries the risk of an unnecessary surgery in a normal individual for the benefit of the recipient. Despite a number of recent studies on the renal function of long-term kidney donors, little attention has been paid to the damaging effects of compensatory hyper-filtration on renal tubular cells immediately after donor nephrectomy. The present study therefore aimed to examine the immediate changes in renal function of the remaining kidney using a sheep model of unilateral nephrectomy. We used the gamma camera-based method to measure the glomerular filtration rate and the tubular excretion values after simultaneous injection of (99m)Tc-diethylene triamine pentaacetic acid and (131)I-ortho-iodohippurate tracers. Compared were the differences in the functions between the remaining left kidney immediately after clamping the right renal pedicle and the baseline values that were measured one week before unilateral nephrectomy. After radionuclide data acquisition was completed, the right kidney was removed. The mean glomerular filtration rate (GFR) increased by 52.3% from the baseline values (29.5 +/- 2.7 to 45.0 +/- 6.7 ml/min; n = 40, p < 0.001), while the mean effective renal plasma flow (ERPF) increased by 40% (225.5 +/- 27.8 to 357.8 +/- 38.94 ml/min; p < 0.001), respectively. Mean filtration fraction was increased from 0.117 to 0.127 immediately after nephrectomy (p < 0.001). We conclude that after unilateral nephrectomy the remaining kidney immediately compensates for the loss of a donated kidney by increasing glomerular filtration rate and effective renal plasma flow.

Renal Function and Size at Young Adult Age After Intrauterine Growth Restriction and Very Premature Birth

Premature birth and intrauterine growth restriction may increase the risk of developing renal disease at adult age. Renal function may already be impaired at young adult age. Cross-sectional study. Very premature individuals (gestational age < 32 weeks) recruited from Project on Premature and Small for Gestational Age Infants and full-term-born controls (37 to 42 weeks) recruited from a children's hospital in Rotterdam, The Netherlands. All individuals were 20 years of age at the time of study. Gestational age and birth weight: premature and small for gestational age (SGA; n = 23), premature and appropriate for gestational age (n = 29), and controls (n = 30). Glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and filtration fraction before and after renal stimulation with low-dose dopamine infusion and oral amino-acid intake. Urine albumin and renal ultrasound. Height, weight, kidney length and volume, GFR, and ERPF were significantly lower in the SGA group than in controls. After adjustment for body surface area, GFR did not differ significantly among groups. Mean ERPF was 71 mL/min/1.73 m(2) (95% confidence interval [CI], 3 to 139) less, but filtration fraction was only 1.3% (95% CI, -0.3 to 3.0) greater, in the SGA group than controls. Renal stimulation significantly increased GFR and ERPF and decreased filtration fraction in all groups. After renal stimulation, ERPF was 130 mL/min/1.73 m(2) (95% CI, 21 to 238) greater in the SGA group than controls, but GFR and filtration fraction did not differ significantly among groups. Microalbuminuria was present in 2 patients (8.7%) in the SGA group, but none in the appropriate-for-gestational-age group or controls. Renal function correlated with renal size. Small sample size. Our findings do not fully support the hypothesis that preterm birth in combination with intrauterine growth restriction contributes to renal function alterations at young adult age. Larger studies are needed to evaluate this hypothesis.

The prognostic value of relative renal function greater than 51% in the pelvi-ureteric junction-obstructed kidney on 99mtechnetium mercaptoacetyltriglycine study

Objective Obstructed kidneys with relative function (RRF) estimates >50% are occasionally noted in 99mtechnetium mercaptoacetyltriglycine renal studies. It is thought that increased RRF might confer some benefit and/or permit delayed intervention. We compared the RRF and absolute renal function, as defined by effective renal plasma flow (ERPF), of obstructed kidneys in the ranges >51%, 40%–50% and <40% RRF before and after pyeloplasty. Methods Twenty children, median age 13.5 months (range 3 weeks–126 months), satisfied criteria for the diagnosis of PUJ obstruction and estimated function >51% (group 1). Their pre- and post-intervention data were compared with 21 children, median age 2 months (range 1 week–126 months), with PUJ obstruction and 40%–50% RRF (group 2); and 21, median age 6 months (range two days–110 months), with RRF below 40% (group 3). Kidneys showing signs of continuing obstruction after surgery were excluded. Results Final ERPF was negatively related to age: younger children, and those with a higher preoperative ERPF, recovered better than older children and those with a lower ERPF ( p < 0.05). Pre- and postoperative mean ERPF in group 1 was 76 (range 21–203) and 102 (6–240) ml/min/1.73 msq respectively. In group 2, these values were 75.2 (30–187) and 130.9 (44–306) ml/min/1.73 msq, and they were 42.6 (5–179) and 80.2 (17–205) ml/min/1.73 msq in group 3. When adjustment was made for preoperative ERPF, there was no evidence that RRF grouping was related to ERPF outcome. The postoperative ERPF of seven of 20 kidneys from group 1 (>51%) was lower than the ERPF before surgery compared to 2/21 in group 2 and 4/21 in group 3, but these differences were not statistically significant ( p = 0.25). Conclusions Most kidneys in each functional range improved when obstruction was relieved. An RRF >51% in the obstructed kidney was not always prognostically beneficial, and may be a warning of impending decompensation in a minority.

Donor Nephrectomy:: A Comparison of Techniques and Results of Open, Hand Assisted and Full Laparoscopic Nephrectomy

Laparoscopic donor nephrectomy (LAP) has been gaining more popularity among kidney donors and transplant surgeons. There have been some concerns about the function of kidney grafts harvested by laparoscopic procedures. We report our results of LAP. Prospective data were collected for our donor nephrectomy operations. A telephone survey was done by an independent investigator on the impact of surgery on quality of life. Graft function was also evaluated by serial serum creatinine and mercaptoacetyltriglycine renal nuclear scans. A total of 100 patients were included in the study; of whom 55 underwent open donor nephrectomy (OD), 28 underwent LAP and 17 underwent hand assisted donor nephrectomy (HAL). Mean patient age was 39 +/- 12 years and it was similar in all groups. Mean operative time was 306 +/- 40 minutes for LAP, 294 +/- 42 minutes for HAL and 163 +/- 24 minutes for OD (p = 0.001). Laparoscopic operative time was decreased to 180 +/- 56 minutes for LAP and 155 +/- 40 minutes for HAL in the last 10 patients. Mean estimated blood loss was 200 +/- 107 cc for LAP, 167 +/- 70 cc for HAL and 320 +/- 99 cc for OD (p = 0.0001). Mean warm ischemia time was 3 +/- 2 minutes for LAP, 2 +/- 2 minutes for HAL and 2 +/- 1 minutes for OD (p = 0.002). Postoperative hospitalization was 2 +/- 2 days for LAP and 3 +/- 2 days for OD (p = 0.01). LAP required 30% less narcotic medicine than OD postoperatively (p = 0.04). There were no major complications in LAP cases and no complete or partial graft loss was noted. Mean followup was 7 months. Recipient creatinine was not significantly different for kidneys harvested by LAP or OD (p = 0.5). Diuretic mercaptoacetyltriglycine renograms were performed in all recipients 1 to 3 days after surgery and mean effective renal plasma flow was similar for the 3 groups (p = 0.9). According to telephone survey results 85% of LAP, 71% of HAL and 43% of OD patients reported a return to normal physical activity within 4 weeks after surgery. Similarly 74% of LAP, 62% of HAL and 26% of OD patients were able to return to work within 4 weeks after surgery. Our data show no significant difference in graft function between LAP and OD. LAP and HAL were safe and complications were minimal. The main difference was that patients treated with LAP and HAL returned to normal physical activity and work significantly earlier than those who underwent OD.

Renal function after autologous bone marrow transplantation in children: a long-term prospective study.

We measured glomerular filtration rate (GFR), effective renal plasma flow (ERPF) and the concentrating capacity of the kidneys in children after autologous BMT. Twenty-six patients had received TBI in their conditioning regimen and 14 patients had received chemotherapy only. Median follow-up was 10 years. Mean GFR before BMT was close to normal in both groups. Mean GFR decreased from 124 [CI 114,134] ml/min/1.73 m(2) before BMT to 99 [CI 82,115] ml/min/1.73 m(2) 6 months after BMT in the + TBI group (P < 0.001). There was no significant change in the -TBI group. Mean ERPF before BMT was high: 1110 [95% CI 830,1390] ml/min/1.73 m(2) in the + TBI group and 910 [CI 570,1250] ml/min/1.73 m(2) in the - TBI group. Six months after BMT, there was a tendency to a decrease in ERPF in the +TBI group, to 760 [CI 580,940] ml/min/1.73 m(2) (P = 0.064). After this initial decrease, GFR and ERPF remained essentially unchanged in both groups. The mean concentrating capacity of the kidneys was normal before and after BMT. In seven patients chronic renal impairment developed after BMT (GFR <70 ml/min/1.73 m(2)). All had received TBI. They had also received more nephrotoxic antibiotics than the other patients. We conclude that TBI was the principal cause of deterioration of renal function after BMT, possibly by limiting compensatory hyperperfusion and resulting in a fall in GFR. Antibiotic treatment may have contributed.

Renal function during and after childhood acute poststreptococcal glomerulonephritis.

It is still debatable whether acute poststreptococcal glomerulonephritis (APSGN) can lead to permanent renal impairment. The clinical, immunological, and histological findings during the acute disease have been described thoroughly, however, the hemodynamic events are still poorly understood. In this retrospective study, the inulin and p-aminohippurate clearances were measured to evaluate glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) within a month of onset of the disease (acute stage) in 26 children, and 2-12 months after onset (follow-up) in 22 children with APSGN. During the acute stage, the mean GFR was 77+/-23 (SD) ml/min per 1.73 m(2), the mean ERPF 537+/-138 ml/min per 1.73 m(2), and the filtration fraction (FF) 14%+/-3%, compared with values for controls of 115+/-11 ml/min per 1. 73 m(2), 607+/-72 ml/min per 1.73 m(2), and 19%+/-2%, respectively (n=42). At follow-up, GFR was 114+/-15 ml/min per 1.73 m(2), ERPF 600+/-68 ml/min per 1.73 m(2), and FF 19%+/-3%. Thus, during the disease both GFR and ERPF fell below values for controls, but later were restored. The GFR, however, was more reduced than the ERPF, as indicated by the reduced FF. This might reflect a relative hyperperfusion of individual nephrons, which might start processes later deleterious to the nephrons. This finding, however, needs to be further investigated and we have therefore started a long-term follow-up of these patients.

Effect of oral cyclosporin on renal function in Crohn's disease.

Twenty-one patients with Crohn's disease were followed prospectively for 24 weeks to examine the effect of a low-dose cyclosporin regime on renal function (initial dose 5 mg/kg reduced by 1 mg/kg every two months to a maintenance of 2 mg/kg). Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured by radioisotope clearance at 0, 6 and 24 weeks. GFR and ERPF fell significantly (mean GFR at baseline: 120.9 ml/min/1.73 m2; at six weeks: 100.9 ml/min/1.73 m2; mean ERPF at baseline: 497.3 ml/min/1.73 m2; at six weeks: 398.5 ml/min/1.73 m2). Following dose reduction, the ERPF remained lower than baseline (mean 408.6 ml/min/1.73 m2), and there was a trend towards the GFR remaining low (mean 111.8 ml/min/1.73 m2). Serum creatinine rose significantly (median pretreatment 72 mumol/liter; median at four weeks 86 mumol/liter) but returned to baseline after dose reduction. Plasma cyclosporin levels and serum creatinine did not help predict the extent of changes in renal function. At low doses, cyclosporin causes changes in renal hemodynamics that may not be reversed by dose reduction.

Effect of Extracorporeal Shock Wave Lithotripsy on Renal Function and Body Height in Pediatric Patients

Although extracorporeal shock wave lithotripsy (ESWL*) is the preferred modality for treatment of most renal and upper ureteral calculi in adults, little is known about its effect on the pediatric population. We carefully followed 12 children 2.2 to 15.3 years old (mean age 9.4) treated with the Dornier HM3 lithotriptor. Effective renal plasma flow was obtained by quantitative 131iodine hippurate scan immediately preceding ESWL and at followup (range 74 to 238 weeks, mean 149). The treated kidney received an average of 1,702 shocks (range 1,000 to 2,200). Mean effective renal plasma flow increased in the treated kidney from 185 cc per minute before ESWL to 217 at followup (p = 0.016) and in the untreated kidney from 191 to 224 (p = 0.0013). Total effective renal plasma flow increased from 376 cc per minute before ESWL to 440 at followup (p = 0.0019). In the treated kidney mean and total effective renal plasma flow increased by 31 (expected 32) and 64 (expected 68) cc per minute, respectively, while in the nontreated kidney mean effective renal plasma flow increased by 33 (expected 36) cc per minute. None of the observed changes in effective renal plasma flow was significantly different from the expected changes using the paired t test at the 95% level. In addition, change in body height was evaluated using standard deviation scores. Mean body height (standard deviation) before ESWL was −0.39 (range −3.2 to 2.0) and at last followup it was −0.26 (range −2.6 to 2.4), which is not statistically significant (p = 0.37). Although these patients continue to be followed and caution is advised, this long-term study indicates that ESWL within the range of shocks delivered to this cohort does not statistically affect linear growth (body height) or renal function in the pediatric population.

Fenoldopam Reverses Cyclosporine-Induced Renal Vasoconstriction in Kidney Transplant Recipients

Cyclosporine causes renal vasoconstriction and reduced renal blood flow that may contribute to chronic nephrotoxicity. This effect has not been consistently reversed by available pharmacologic agents. The efficacy of orally administered fenoldopam, a dopamine-1 (DA-1) agonist with renal vasodilator properties, was evaluated in six patients whose condition was stable 3 to 6 months following renal transplantation. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured by inulin and p-aminohippurate (PAH) clearances, respectively, at baseline, after the acute oral administration of 100 mg of fenoldopam, and following 3 weeks of chronic oral fenoldopam therapy (100 mg thrice daily). Mean ERPF increased from 3.15 ± 0.17 mL/s/1.73 m2 (189 ± 10 mL/min/1.73 m2) at baseline to 3.48 ± 0.17 mL/s/1.73 m2 (209 ± 10 mL/min/1.73 m2) 4 hours after acute administration of fenoldopam (P = 0.04). Urine flow rate and fractional excretion of sodium also increased after acute administration, but not significantly. Mean systolic (SBP) and diastolic blood pressure (DBP) decreased maximally by 18 and 6 mm Hg, respectively, and mean pulse rate increased maximally by 8 bpm between 75 and 90 minutes after both acute and chronic administration. GFR was unchanged following both acute and chronic administration. The increase in ERPF was not maintained to the end of the dosing interval during chronic administration, probably due to the short half-life of fenoldopam, However, the renal vasodilatory response was still observed 3 to 4 hours after readministration of the drug following 3 weeks of oral dosing. Thus, fenoldopam significantly reverses the renal vasoconstriction caused by cyclosporine in renal transplant recipients. Further evaluation of fenoldopam in preventing cyclosporine-induced nephrotoxicity appears warranted.

Renal functional response to dopamine during and after arteriography in patients with chronic renal insufficiency.

The potential renal vasodilatory effect of dopamine in improving renal function after arteriography was studied. Sixty patients with preexisting renal insufficiency were prospectively randomized into two groups. Patients in the treated group (n = 30) received an infusion of dopamine for 12 hours starting at the beginning of arteriography. Patients who received placebo infusion with arteriography (n = 30) served as controls. The study was conducted in two different time intervals. In the first interval, serum creatinine levels and 12-hour creatinine clearance values were obtained before and immediately after arteriography in 12 patients in the dopamine group and 13 patients in the control group. In the second interval, the same variables were measured before arteriography and for 3 consecutive days after arteriography in 18 patients in the dopamine group and 17 patients in the control group. Serum creatinine levels became significantly elevated in the control group on the 1st day and remained so on the 3rd day after arteriography, whereas the dopamine group did not show significant elevation of these levels. Creatinine clearance decreased in the control group on the 1st day, but this deterioration was not sustained on the 3rd day. In the dopamine group, there was no deterioration in creatinine clearance on either day, and mean effective renal plasma flow during and after arteriography was greater.

Renal Effects of Ibuprofen, Piroxicam, and Sulindac in Patients with Asymptomatic Renal Failure

To evaluate the effects of three chemically distinct nonsteroidal anti-inflammatory drugs (NSAIDs) on renal function in patients with asymptomatic, mild but stable chronic renal failure. Prospectively randomized, triple-crossover study with at least 1-month washout between each of three treatment periods. Inpatient and outpatient clinical research center of a university teaching hospital. Convenience sample of 12 women with serum creatinine levels between 130 and 270 mumols/L (1.5 and 3.0 mg/dL). Mean glomerular filtration rate +/- standard error was 0.36 +/- 0.03 mL/s.m2 (37 +/- 3 mL/min.1.73 m2); mean effective renal plasma flow was 1.6 +/- 0.18 mL/s.m2 (166 +/- 19 mL/min.1.73 m2). Patients received ibuprofen, 800 mg three times daily; piroxicam, 20 mg daily; and sulindac, 200 mg twice daily for 11 days. Treatment was discontinued if serum creatinine rose by 130 mumols/L (1.5 mg/dL) or serum potassium exceeded 6 mmol/L (6 mEq/L). Three patients met our criteria for stopping ibuprofen by day 8; however, all patients completed piroxicam and sulindac therapy. When the three patients in whom ibuprofen was withdrawn were rechallenged with ibuprofen, 400 mg three times daily, two again developed evidence of acute renal deterioration. All three regimens suppressed renal prostaglandin production. These findings indicate that a brief course of ibuprofen, a compound widely used on a nonprescription basis, may result in acute renal failure in patients with asymptomatic, mild chronic renal failure. Additional studies are needed to assess the risk of piroxicam and sulindac in patients with more pronounced renal impairment and in patients receiving longer courses of therapy, which, according to our data, may result in drug accumulation.

Experiments with the double isotope single-injection method for determining glomerular filtration rate and effective renal plasma flow in veal calves

Single injections of the radiochemicals Cr51-EDTA and I125-ortho-iodohippurate (I125-OH) were used simultaneously to measure the glomerular filtration rate (GFR) and effective renal plasma flow (ERPF), respectively, in 26 calves weighing between 37 kg and 90 kg. The mean GFR was 2.31 ml per minute per kg and the mean ERPF was 9.62 ml per minute per kg. These values are very similar to the GFR and ERPF measured in young calves and adult cattle by using constant infusions of inulin and para-aminohippurate as marker substances. Correlation coefficients of the order of 0.70 were found between clearance values and body-weights. The method described is rapid and reliable.

Renal function before and after unilateral ephrectomy in renal donors

Measurements of glomerular filtration rate (GFR), effective renal plasma flow (ERPF), tubular maximum reabsorption of glucose (Tmglucose) and secretion of para-aminohippurate (Tmpah), clearance of inorganic phosphate (Cphosphate) and uric acid (Curic acid), urine diluting capacity (CH2O) and urinary net acid excretion (UH + V) were made before and 10 to 14 days after unilateral nephrectomy in seven healthy renal donors. Comparisons were made between the functions of the remaining kidney and 50% of pre-uninephrectomy values. Mean post-uninephrectomy GFR increased by 36%, and mean ERPF, 55%. Tmglucose, Tmpah, Cphosphate, uric acid, CH2O, UH + V increased significantly, after uninephrectomy. The increase in Tmpah, Tmglucose and CH2O is proportional to the rise in GFR while the increase in Cphosphate, Curic acid and UH + V is proportionally greater than the increase in GFR. The changes in post-uninephrectomy renal handling of phosphate are not due to an increase in parathyroid hormone secretion.