The contribution of residual renal function to overall nutritional status in chronic haemodialysis patients.

BACKGROUND: The benefits of residual renal function (RRF) in peritoneal dialysis patients have been described frequently. However, previous reports have shown that RRF diminished faster in haemodialysis (HD) patients than in peritoneal dialysis patients, and in most of the studies in HD patients, RRF was ignored. In this study, the RRF in chronic HD patients was studied to assess its impact on patients' nutritional status. METHODS: In 41 chronic HD patients with at least a 2-year history of HD treatment, RRF was determined by a urine collection for 7 consecutive days. Nutritional parameters, such as percentage body fat, fat-free mass index, serum albumin concentration and normalized protein catabolic rate, were also measured. RESULTS: In all 41 patients, mean weekly total Kt/V urea was 4.88 and renal Kt/V urea was 0.65. RRF was well correlated with serum albumin concentration, but dialysis Kt/V urea was not. One year after the start of this study, RRF and nutritional indices were re-examined and patients were classified into two groups: with RRF, preserved residual renal diuresis over 200 ml/day (mean, 720 ml; range, 230-1640 ml), N=23; and without RRF, persistent anuria (mean, 51 ml; range, 0-190 ml), N=18. At the start of this study, the mean serum albumin concentration and mean normalized protein catabolic rate in patients with RRF were 3.84 g/dl and 1.16 g/kg/day, respectively, which were significantly higher than those in patients without RRF (P=0.02 and P=0.0002, respectively), despite total (renal+dialysis) Kt/V urea being equal in both groups. During the 1-year study period, there was no significant change in total Kt/V urea in either group. Mean serum albumin concentration increased to 4.05 g/dl in patients with RRF, but did not change significantly (from 3.66 to 3.62 g/dl) in patients without RRF. The same trend was observed in all other parameters. CONCLUSION: Over half of our HD patients had sufficient RRF. RRF itself may have a beneficial effect on nutritional parameters, and it is important to determine RRF over time, even in chronic HD patients.     

Continuous renal replacement therapy: does technique influence azotemic control?

BACKGROUND AND OBJECTIVES: Different techniques of continuous renal replacement therapy (CRRT) might have different effects on azotemic control. Accordingly, we tested whether continuous veno-venous hemodiafiltration (CVVHDF) or continuous veno-venous hemofiltration (CVVH) would achieve better control of serum creatinine and plasma urea levels. DESIGN: Retrospective controlled study. SETTING: Two tertiary Intensive Care Units. PATIENTS: Critically ill patients with acute renal failure (ARF) treated with CVVHDF (n = 49) or CVVH (n = 50). Interventions: Retrieval of daily morning urea and creatinine values before and after the initiation of CRRT for up to 2 weeks of treatment. MEASUREMENTS AND RESULTS: Before treatment, serum urea and creatinine concentrations were significantly lower in the CVVH group than in CVVHDF group (urea: 31.0 +/- 15.0 mmol/L for CVVHDF and 24.7 +/- 16.1 mmol/L for CVVH, p = 0.01, creatinine: 547 +/- 308 micromol/L vs. 326 +/- 250 micromol/L, p < 0.0001). These differences were still significant after 48 h of treatment (urea: 20.1 +/- 8.3 mmol/L vs. 14.1 +/- 6.1 mmol/L; p = 0.0003, creatinine: 360 +/- 189pmol/L vs. 215 +/- 118 micromol/L; p < 0.0001). Throughout the duration of therapy, mean urea levels (22.3 +/- 9.0 mmol/L for CVVHDF vs. 16.7 +/- 7.8 mmol/L for CVVH, p < 0.0001) and mean creatinine levels (302 +/- 167 vs. 211 +/- 103 micromol/L, p < 0.0001) were better controlled in the CVVH group. CONCLUSIONS: CRRT strategies based on different techniques might have a significantly different impact on azotemic control.     

Estimation of residual glomerular filtration rate in dialysis patients from the plasma cystatin C level.

BACKGROUND: Residual renal function influences morbidity, mortality and quality of life of chronic dialysis patients. Residual glomerular filtration rate (rGFR) is therefore an important parameter in the follow-up of these patients. Because rGFR is measured as the mean of creatinine and urea clearance, a complete 24 h urine collection is essential, but often very difficult to manage for these patients. METHODS: We investigated if plasma cystatin C (cysC) could give a good estimate of rGFR in dialysis patients and compared it to the measured rGFR, as well as to the rGFR estimate obtained with the Modification of Diet in Renal Disease (MDRD) formula. A total of 465 patients were included in this study. CysC levels of 215 haemodialysis (HD) and 95 chronic ambulatory peritoneal dialysis (PD) patients were used to derive a formula for rGFR. This formula was tested in the validation group of 107 HD and 48 PD patients. RESULTS: The cysC formula derived in the modelling group was rGFR = -0.70 + 22 x (1/cysC). The mean estimated rGFR obtained with this formula in the validation group was not significantly different from the mean measured rGFR: difference 0.19 ml/min/1.73 m(2), 95% confidence interval (CI) -2.37 to 2.75 ml/min/1.73 m(2). The MDRD formula gave a larger difference from the mean measured rGFR (3.13 ml/min/1.73 m(2)) and a much wider 95% CI (-1.29 to 7.55 ml/min/1.73 m(2)). A separate model for HD and PD patients did not improve the estimation of rGFR. CONCLUSIONS: The cysC formula showed better accuracy and precision than the MDRD formula. Therefore the cysC formula and not the MDRD formula should be used to calculate rGFR in dialysis patients when no 24 h urine sample is available.     

Serum cystatin C measured by a sol particle homogeneous immunoassay can accurately detect early impairment of renal function

BACKGROUND: A sol particle homogeneous immunoassay (SPIA) is a method to measure the serum cystatin C (cysC) level as a marker of the glomerular filtration rate (GFR). Recently, formulas to convert measured cysC to GFR have been developed. METHODS: A total of 154 patients (46 +/- 18 years old) who had undergone renal biopsy, sodium thiosulfate clearance (C thio) and 24-h creatinine clearance (24-hCcr) tests were subjects for the study. Their serum cysC levels were determined by SPIA. RESULTS: Multiple regression analysis revealed C (thio) and age as independent variables for serum creatinine concentration (Cr), while only C thio affected cysC. The equations using Cr or cysC showed significant correlation with C thio. Receiver-operating curve ROC analysis revealed that cysC and 24-hCcr shared comparable power to detect patients with GFR < 90 or 60 ml/min/1.73 m2 (AUC = 0.862 and 0.943 vs. AUC = 0.842 and 0.943, respectively), while Cr (AUC = 0.881) and MDRD2 (AUC = 0.888) showed slightly inferior ability to detect 60 ml/min/1.73 m2 than other parameters in the female population. The cut-off point of cysC and Cr obtained from the ROC analysis demonstrated strong power to detect patients with C thio < 90 ml/min/1.73 m2 or C thio < 60 ml/min/1.73 m2. According to CKD stages, the mean values of each equation were significantly different, like that demonstrated by 24-hCcr. CONCLUSION: SPIA could determine cysC levels that detected early renal impairment. The accuracy of cysC to detect early renal impairment may be superior to that of Cr in females, while it would be comparable to that of CG or MDRD when they are corrected by sex and age. Both cysC itself and cysC equations are effective to monitor the progress of renal impairment. The future standardization of cysC measurements and development of novel equation of cysC would contribute to the further improvement of GFR estimation in clinical practice.     

Effect of iodinated contrast agents on residual renal function in PD patients.

BACKGROUND: Residual renal function (RRF) is an important predictor of outcome in peritoneal dialysis (PD) patients. Although increasing emphasis has been placed on preserving RRF, the nephrotoxicity associated with contrast medium administration in PD patients remains a controversial issue. In the present prospective study, we evaluated the evolution of RRF 2 weeks after iodinated contrast medium administration (ICMA) in a group of stable PD patients, and compared it with that in a non-treated control group of stable PD subjects. METHODS: The study was conducted from January 2003 to October 2004. RRF was quantified by the average of 24 h urinary urea and creatinine clearance and peritoneal creatinine clearance (PcrCl) were analyzed, the levels of which were analysed prior to and 2 weeks following ICMA in 36 PD patients and also assessed at the same time points in a group of 36 PD non-ICMA control subjects, matched according to RRF characteristics. Two weeks following ICMA, the values for RRF, daily urine volume and PcrCl were assessed against those at baseline, and the evolution of RRF was compared between the two groups. In the ICMA group, this study was performed with adequate pre-hydration and a minimum dose of contrast medium. RESULTS: Compared with baseline values, RRF, daily urine volume and PcrCl were not found to be significantly different 2 weeks after ICMA (7.0+/-4.3 vs 7.2+/-4.3 ml/min/1.73 m(2), P = 0.12; 1324+/-696 vs 1360+/-755 ml/day, P = 0.5; and 41.1+/-9 vs 40.6+/-9 l/week/1.73 m(2), P = 0.6, respectively). Following ICMA, variations in RRF and daily urine volume were found to be comparable with those of the control group (0.1+/-0.5 vs 0.1+/-0.5 ml/min/1.73 m(2), P = 0.9; 36+/-440 vs 40+/-493 ml/day, P = 0.8, respectively). CONCLUSION: In this study, 2 weeks following ICMA, no accelerated decline in RRF was determined in stable PD patients with adequate pre-hydration, i.e. subjects treated under optimal circumstances compared with the control group.     

Continuous venovenous hemodiafiltration versus hemodialysis as renal replacement therapy in patients with acute renal failure in the intensive care unit

OBJECTIVE: Hemodialysis (HD) and continuous venovenous hemodiafiltration (CVVHDF) have been adopted as forms of renal replacement therapy (RRT) in patients with acute renal failure (ARF). Although CVVHDF has many advantages, previous studies reported no definite improvement in survival rate compared to HD. MATERIAL AND METHODS: In this retrospective study, 148 intensive care unit patients underwent HD (70 males, 25 females; mean age 45 +/- 17 years) or CVVHDF (42 males, 11 females; mean age 52 +/- 18 years). The severity of illness was estimated at the initiation of RRT and on the third day of RRT and presented using the APACHE III scoring system. The number of organ failures was checked at the initiation of RRT. RESULTS: The survival rate was 46% in the HD group and 21% in the CVVHDF group (p = 0.002). CVVHDF was applied to the more severely ill patients, who had longer periods using a ventilator (p = 0.002) and/or vasopressor (p < 0.001), higher numbers of organ failures (p < 0.001) and higher initial APACHE III scores (p < 0.001). Among patients with APACHE III scores > 103, the survival rate was 13% in the CVVHDF group and 0% in the HD group. In patients with kidney failure and failure of two other organs, the survival rate was 9% in the HD group and 36% in the CVVHDF group (p = 0.035). CONCLUSION: The mortality rate in the CVVHDF group was higher than that in the HD group, which may have been because CVVHDF was applied to the more severely ill patients. In contrast, CVVHDF may give a chance of survival to patients with APACHE III scores > 103 and may be more useful than HD in patients with failure of three or more organs.     

Effects of residual renal function in haemodialysis patients

Thirty-six haemodialysis patients on treatment for more than six months were studied for residual renal function (RRF). Twenty patients were anuric. The remaining 16 patients with RRF excreted 35–1600 ml urine/day with creatinine clearance ranging 0.17–6.95 ml/min. Patients with RRF were on dialysis therapy for shorter periods than those with anuria (25.5±18.5 vs. 101.7±14.2 months, p=0.001). Twelve out of 20 anuric patients had had previous renal transplantation, whereas none of those with RRF had been transplanted (p=0.0006). Interdialytic weight gain, serum potassium and phosphate were lower in patients with RRF. Serum phosphate and uric acid were correlated with their respective urinary excretion rates (p=0.013 and 0.005, respectively), but interdialytic weight gain could not be correlated with urinary output. Creatinine clearance significantly correlated with urinary excretion of potassium, sodium, phosphate and uric acid. In this series of patients a previous unsuccessful renal transplantation was an important factor in the loss of RRF. The presence of RRF contributed to the regulation of the blood levels of phosphate and the excretion rate of potassium, sodium and uric acid.     

Timing of replacement therapy for acute renal failure after cardiac surgery

OBJECTIVE: Acute renal failure (ARF) following cardiac surgery remains a significant cause of mortality. The aim of this study is to compare early and intensive use of continuous veno-venous hemodiafiltration (CVVHDF) with conservative usage of CVVHDF in patients with ARF after cardiac surgery. MATERIALS AND METHODS: Due to ARF, CVVHDF was required in two groups of a total of 61 adult patients (1.79% of all patients). Group 1 included 27 patients while Group 2 included 34 patients. CVVHDF was performed on Group 1 when creatinine level exceeded 5 mg/dL, or potassium level exceeded 5.5 mEq/L irrespective of the urine output. CVVHDF was performed on Group 2 when urine output was less than 100 mL within consecutive 8 hours, with no response to 50 mg furosemide with the supplementary criterion that urine sodium concentration should be >40 mEq/L before the administration of furosemide. RESULTS: The mean elapsed time between the surgery and the initiation of CVVHDF was 2.56 +/- 1.67 days in Group 1 and 0.88 +/- 0.33 days in Group 2 (p = 0.0001). The mean intensive care unit (ICU) stay for Group 1 was 12 +/- 3.44 days and 7.85 +/- 1.26 days for Group 2 (p = 0.0001). ICU mortality rate was 48.1% for Group 1 and 17.6% for Group 2 (p = 0.014). The overall hospital mortality rate was 55.5% for Group 1 and 23.5% for Group 2 (p = 0.016). CONCLUSION: Recognition of ARF and early beginning of the CVVHDF are extremely important. The sooner the ARF after surgery is recognized and CVVHDF is performed, the higher the likelihood of the reduction of the hospital mortality.     

Increasing blood flow increases kt/V(urea) and potassium removal but fails to improve phosphate removal

BACKGROUND: Hyperphosphatemia and hyperkalemia are major determinants of morbidity and mortality in hemodialysis patients. Half of the dialysis population suffers from hyperphosphatemia which is now recognized as an important cardiovascular disease risk factor. It is, therefore, necessary to improve the removal of these molecules. In this study, we investigated the effect of enhancing blood flow on Kt/V for urea (Kt/Vu), potassium and phosphate removal. METHODS: Thirteen patients were investigated in a randomized, cross-over, prospective study using 3 blood flows (Qb) of 200,250 and 300 ml/min which gave 39 standardized high-flux hemodialysis treatments. Effective blood flows were measured by ultrasonic flow meter. Quantification of delivered dialysis dose was performed by partial dialysate and ultrafiltrate collection for the determination of potassium and phosphate removal and by blood urea concentrations for determination of Kt/Vu. RESULTS: Kt/Vu rose significantly from 1.10 +/- 0.14 to 1.22 +/- 0.14 and finally to 1.39 +/- 0.16 (p = 0.0001) with increasing Qb similar to the increase in potassium removal from 53.0 +/- 2.4 to 63.4 +/- 2.6 and to 74.2 +/- 3.8 mMol (p = 0.01). Phosphate removal only improved from 28.1 +/- 1.3 to 31.4 +/- 1.5 (p = 0.050) when Qb was increased from 200 to 250 ml/min but remained unchanged at 31.2 +/- 1.5 mMol (NS compared to phosphate removal at Qb = 250 ml/min) when Qb was increased to 300 ml/min. CONCLUSIONS: Increasing delivered Kt/Vu and potassium removal with higher Qb fails to produce the same desired effect with phosphate removal during high-flux hemodialysis.     

Standard versus high-dose CVVHDF for ICU-related acute renal failure

The effect of dosage of continuous venovenous hemodiafiltration (CVVHDF) on survival in patients with acute renal failure (ARF) is unknown. In this study, 200 critically ill patients with ARF were randomly assigned to receive CVVHDF with prefilter replacement fluid at an effluent rate of either 35 ml/kg per h (high dosage) or 20 ml/kg per h (standard dosage). The primary study outcome, survival to the earlier of either intensive care unit discharge or 30 d, was 49% in the high-dosage arm and 56% in the standard-dosage arm (odds ratio 0.75; 95% confidence interval 0.43 to 1.32; P = 0.32). Among hospital survivors, 69% of those in the high-dosage arm recovered renal function compared with 80% of those in the standard-dosage arm (P = 0.29); therefore, a difference in patient survival or renal recovery was not detected between patients receiving high-dosage or standard-dosage CVVHDF.     

Cystatin C as marker of residual renal function in patients on peritoneal dialysis: relation with parameters of peritoneal function

INTRODUCTION: Cystatin C (CysC) is a nonglycosylated protein of low molecular weight not influenced by age, sex or inflammation. The aim of this paper is to ascertain the usefulness of serum CysC level determination in peritoneal dialysis (PD) patients. MATERIAL AND METHODS: CysC serum levels were determined in 80 PD patients. The mean age of patients was 53.7 +/- 15 years, with 15.3 +/- 25.8 months on PD. Thirty-three percent were on continuous ambulatory peritoneal dialysis (CAPD) and 66.3% on automated peritoneal dialysis (APD). Fourteen patients (17%) had no residual renal function (RRF). RESULTS: Mean CysC levels were 5.8 +/- 1.4 mg/L, without differences between men (5.5 +/- 1.4 mg/L) and women (5.6 +/- 1.5 mg/L, NS). There was no correlation between CysC levels and age, weight, height or time on PD. Anuric patients had CysC levels significantly higher than non-anuric (6.7 +/- 1.4 vs. 5.3 +/- 1.3 mg/L, p<0.001). CysC levels showed an inverse correlation with RRF (r=-0.60, p<0.001) and residual urine volume (r=-0.58, p<0.001). CONCLUSIONS: In conclusion, serum CysC levels had the same statistical significance as plasma creatinine levels, and they are not influenced by peritoneal transport in PD patients. Consequently, both parameters are valid RRF markers.     

Association between inflammation and changes in residual renal function and peritoneal transport rate during the first year of dialysis.

BACKGROUND: Peritoneal transport rate, a major determinant of peritoneal dialysis (PD) patient survival, increases in most patients starting on PD, while in other patients peritoneal transport rate may decline. Although several factors may contribute to changes in peritoneal transport rate, inflammation is known to be associated with a high peritoneal transport rate, and residual renal function (RRF), which often declines after start of PD, may also be related to inflammation. Therefore, we hypothesized that changes in peritoneal transport rate during patients' first year on PD and declining RRF may be linked with inflammation. METHODS: A total of 76 PD patients (40 males, mean age 56.8+/-14.1 years), who underwent two peritoneal equilibration tests at a mean of 0.4 months and 1 year after beginning PD, were included in the study. Based on the change in dialysate to plasma creatinine concentration ratio at 4-h dwell (D/P Cr) during first year on PD, the patients were divided into decreased or unchanged (group DUC; n=22) and increased (group I; n=54) groups. RESULTS: Initially, group I had a lower proportion of high transporters and more often high serum C-reactive protein (sCRP, > or =10 mg/l) and lower RRF compared with the DUC group. In group I, serum albumin and RRF decreased significantly and dialysate protein loss and glucose absorption increased significantly during the first year on PD. When patients were divided into two groups based on median change in RRF (1.9 ml/min), patients with a decrease in RRF >1.9 ml/min during first year on PD had a higher proportion of high sCRP, higher D/P Cr, and higher changes in D/P Cr compared to patients with a decrease in RRF < or =1.9 ml/min. Patients with elevated sCRP at one year included a higher proportion of patients who had high sCRP at the start of PD, higher increase in D/P Cr, lower serum albumin, lower RRF, and more decrease in RRF during first year on PD compared with patients having normal sCRP. RRF was inversely correlated with changes in D/P Cr during the first year on PD (r=-0.28, P=0.02). Multiple regression analysis revealed that the only factors affecting changes in D/P Cr were high sCRP and a low RRF. CONCLUSIONS: Our preliminary short-term study suggests that changes in peritoneal transport rate during patients' first year on PD may be linked with inflammation and declining residual renal function. Inflammation and residual renal function were identified as the only independent factors determining peritoneal transport rate during the first year on PD. It is possible that inflammation may cause both an increase in peritoneal transport rate and a decline in residual renal function, or that the decline in residual renal function and the increase in peritoneal transport rate may induce or aggravate inflammation. Further studies are needed to confirm these findings.     

The outcome for pediatric patients on peritoneal dialysis

BACKGROUND: The adverse effects of peritonitis and of the duration of dialysis on dialysis adequacy and clinical outcome were evaluated in this study. METHODS: The study comprised 24 chronic peritoneal dialysis patients who were followed up at least for 12 months. Casual blood pressure (BP) measurements, echocardiographic evaluation, peritonitis rate, hemoglobin (Hb), serum albumin, normalized protein catabolic rate (nPCR), total Kt/Vurea, weekly creatinine clearance (CCr), residual renal function (RRF), removal of fluid and dose of recombinant human erythropoietin (EPO) were evaluated. RESULTS: Mean age of the patients was 15.3 +/- 3.6 years. Mean follow-up was 50.4 +/- 26.8 months. Peritonitis rate was calculated as 1 episode/32.7 patient-months. Systolic hypertension was detected in 14 patients (58%) and diastolic hypertension in 15 (63%). RRF showed a negative correlation with duration on dialysis (r=-0.623, p=0.006).There was no significant correlation between RRF and nPCR, Hb, hematocrit, albumin and dose of EPO. A negative correlation was found with left ventricular mass index and fluid removal (r=-0.461, p=0.041). Higher doses of Kt/Vurea are associated with higher protein intake (r=0.503, p=0.024). A positive correlation was found between Kt/Vurea and Hb and Hct levels (r=0.460, p=0.009, and r=0.528, p=0.017, respectively). Dialysis adequacy tests were found not to be affected by the frequency of peritonitis. CONCLUSION: The most important factor for the prevention of hypervolemia in chronic peritoneal dialysis patients is RRF. The concept of adequate dialysis should include normal volume homeostasis, control of blood pressure and adequate nutrition.     

Low prevalence of hyperphosphatemia independent of residual renal function in peritoneal dialysis patients.

OBJECTIVE: Our objective was to evaluate serum phosphorus control in patients undergoing continuous ambulatory peritoneal dialysis, with and without residual renal function, by investigating the metabolic balance of phosphorus. METHODS: We assessed serum phosphorus levels in 205 patients undergoing continuous ambulatory peritoneal dialysis (CAPD). The clinical factors related to serum phosphorus were also examined, including dietary phosphate intake, dietary protein intake (DPI), phosphate removal through urine and dialysate, doses of phosphorus binder and vitamin D, and serum intact parathyroid hormone (PTH) levels. Nutritional indexes, including serum albumin (Alb), lean body mass (LBM), hand-grip strength (HGS), and subjective global assessment (SGA), were also assessed. Dialysis adequacy and residual renal function (RRF) were calculated by a standard technique. Patients with RRF <2 mL/min were viewed as having no significant RRF. Hyperphosphatemia was diagnosed in patients with serum phosphorus levels >1.78 mmol/L. RESULTS: The mean serum phosphorus level of all patients was 1.6 +/- 0.5 mmol/L (mean +/- SD). Only 58 of 205 patients (28%) had hyperphosphatemia. The average DPI was 0.8 +/- 0.3 g/kg/d, whereas the average dietary phosphorus intake was 691 +/- 201 mg/d. There were no differences in mean serum phosphorus levels or incidents of hyperphosphatemia between patients with and without RRF (1.6 +/- 0.4 mmol/L vs. 1.7 +/- 0.5 mmol/L, P = .256; 22% vs. 31%, P = .336). Although total phosphorus removal through urine and dialysate was lower in the 115 patients without RRF than in the 90 patients with RRF (270 +/- 106 mg vs. 333 +/- 129 mg, P = .000), they simultaneously had a lower dietary phosphorus intake (656 +/- 191 mg vs. 713 +/- 215 mg, P = .046). In addition, patients without RRF had significantly lower DPI, Alb, LBM, and right HGS levels than patients with RRF (P < .01-.05). In those without RRF, the 79 patients without hyperphosphatemia had significantly lower DPI, LBM, and HGS levels, and a higher prevalence of malnutrition diagnosed by SGA, than the 36 patients with hyperphosphatemia (P < .001-.05). However, in patients with RRF, there was no difference in nutritional index between patients with and without hyperphosphatemia (P > .05). CONCLUSION: A relatively lower prevalence of hyperphosphatemia existed in CAPD patients both with and without RRF, which may be associated with incremental dialysis, the correct administration of phosphorus binder, and a lower protein and phosphorus intake. However, patients without RRF, especially those without hyperphosphatemia, ran the risk of malnutrition, despite a well-controlled phosphorus intake.     

Impact of residual renal function in children on hemodialysis

Residual renal function (RRF) contributes to dialysis adequacy as well as lower mortality and morbidity in dialysis patients. Even very small changes in glomerular filtration rate (GFR) account for considerable improvements in complications of dialysis. The purpose of this cross-sectional study is to determine the possible contribution of RRF to hemodialysis clearance and to compare the biochemical markers of this patient group with anuric patients. Ten patients with RRF on chronic hemodialysis for more than 6 months were enrolled in the study. Duration of dialysis was not different between the two patient populations. Average GFR was 3.4±2.6 ml/min in the group with RRF. Cholesterol, albumin, and triglyceride levels were not different between the groups. Residual renal urea clearance enhanced mean Kt/V of patients from 1.29 to 1.52. However erythropoietin and renin levels were higher in the group with RRF (P=0.019, P=0.044, respectively). There was a positive correlation between erythropoietin, renin levels, and average GFR of all patients (r=0.69, P=0.002, r=0.60, P=0.014). We conclude that RRF plays a greater role in pediatric patients on hemodialysis than previously recognized, and knowledge about patients’ RRF should assist in improved overall management. Received: 31 January 2001 / Revised: 27 June 2001 / Accepted: 28 June 2001     

Regional citrate anticoagulation in continuous venovenous haemodiafiltration using commercial solutions.

BACKGROUND: Treatment with trisodium citrate provides an effective means of regional anticoagulation during continuous renal replacement therapy (CRRT). We evaluated the efficacy, safety and cost of a regional citrate anticoagulation protocol using commercial solutions in 17 critically ill patients treated with continuous venovenous haemodiafiltration (CVVHDF). We performed a total of 22 sessions. METHODS: We delivered an A.C.D-A(541(R)) solution containing 112.9 mmol/l disodium citrate (3.22%) at a median rate of 260 (190-280) ml/h via the pre-filter port of a COBE PRISMA with an AN-69 dialyser, while adjusting the rate to maintain post-filtered ionized calcium (iCa(2+)) between 0.25 and 0.4 mmol/l. Plasma iCa(2+) was maintained at >1.1 mmol/l by infusion of calcium chloride at a median rate of 1.70 (1.36-2.27) mmol/h. The dialysate was easily modified according to the acid-base status of each patient. Both replacement and dialysate solutions were delivered at 1200 ml/h. Each session was scheduled for 48 h and biological parameters were assessed every 6 h. RESULTS: The mean dialyser survival was 39 +/- 11 h (median 41.5 h; range 13-48 h). We observed dialyser clotting in four cases (18%). There were no bleeding events or modifications of coagulation parameters. The citrate solution, replacement solution and dialysate were obtained as commercial products. Both the replacement and dialysate solutions contained calcium. The extra cost of this technique was 25 euro;/day as compared to anticoagulation with heparin. CONCLUSIONS: We designed an efficient method of regional citrate anticoagulation for CVVHDF by using commercial solutions. The monitoring of patients was as intensive as during heparin anticoagulation for CRRT. Because of the higher cost of this method, it should be proposed only for patients with high bleeding risk.     

Impact of Residual Renal Function on Dialysis Adequacy in Paediatric CAPD Patients

This study was designed to determine the impact of residual renal function (RRF) on dialysis adequacy indices and clinical outcome parameters in paediatric CAPD patients. Seventeen children on CAPD were included. Residual renal function was described by residual diuresis (UO: urine output), residual renal solute clearances [RR.KT/V (residual renal KT/V), RR.Ccr (residual renal creatinine clearance) and GFR (glomerular filtration rate)]. Pearson's correlation coefficients and multiple linear regression analysis were used in statistical analysis. Mean W.KT/V (weekly KT/V) vas 1.97±0.6 and mean T.Ccr (total Ccr) was 56±32 L/week/1.73 m². Both of these indices were found to be strongly correlated with RRF (GFR, UO, RR.KT/V and RR.Ccr) (p<0.001), but not with peritoneal solute clearances. W.KT/V was found to be influenced essentially by RR.KT/V (p<0.001) and also dialysate fill volume (DV) (p<0.01). T.Ccr was influenced primarily by RR.Ccr (p<0.001) and serum cr levels (p<0.05). In addition significant positive correlations were detected between serum albumin, haemoglobin (Hb), haematocrit (Htc) levels and residual diuresis (p<0.05) and a significant negative correlation was found between mean blood pressure and residual diuresis (p<0.05). It was concluded that the mean values of W.KT/V and T.Ccr were heavily influenced by RRF. Almost all variations in W.KT/V and T.Ccr represented changes in RRF. In addition, anaemia, hypertension and hypoalbuminaemia, which are known as clinical criteria of inadequate dialysis, were found to be influenced by residual diuresis. Thus one of the goals of paediatric nephrologists must be the preservation of renal reserve. Since the rate of decline in RRF was significantly lower in CAPD, it should be the first choice of long-term maintenance dialytic therapy for children who have residual renal reserve.     

Glutamine and Other Amino Acid Losses During Continuous Venovenous Hemodiafiltration

Abstract: Serum amino grams and daily losses of glutamine (Gin) and other amino acids (AAs) into diafiltrate were measured during the first 5 days of continuous venovenous hemodiafiltration (CVVHDF) in 6 ICU patients with acute renal failure (ARF). Four patients had ARF as a part of multiple organ failure (MOF) of septic origin, and 2 patients had isolated ARF because of primary renal disease. During the study, all the patients received defined total parenteral nutrition (TPN). The mean daily AA losses into dialysate were relatively low (0.61 ± 0.1 g N ) and reached 4.5% of the daily AA substitution. Gln represented 32.7 ± 5.9% of the total AA losses (0.19 ± 0.04 g N ). Serum levels of Gin (p = 0.002) and of most other AAs were significantly lower in the patients than in the control subjects (AA analysis in 16 healthy volunteers). Phenylalanine (Phe) was the only AA that was increased significantly (p < 0.01) in the patients. The mean patient serum concentrations of Phe and tyrosine were significantly higher (p < 0.03) than the correspondent concentrations in dialysate, but the lysine concentration was higher in dialysate (p < 0.03). The serum and dialysate concentrations of other AAs did not differ. Gin in serum decreased significantly (p < 0.03) on the second day of CVVHDF but returned to the baseline levels subsequently. Serum concentrations of Phe increased on the second day of CVVHDF (p < 0.05). Serum concentrations of other AAs remained stable during the whole study. We conclude that Gin losses into dialysate during CVVHDF are relatively low, but CVVHDF itself may induce changes in Gin metabolism and distribution that are reflected by a decrease of serum Gin levels at the institution of this treatment. Therefore, the need for Gin supplementation in ICU patients is even greater in the first days of CVVHDF.     

Important differentiation of factors that predict outcome in peritoneal dialysis patients with different degrees of residual renal function.

BACKGROUND: Residual renal function (RRF) is an important predictor of outcome in peritoneal dialysis (PD) patients. Whether results from survival studies in dialysis patients with RRF can also be extrapolated to anuric patients remains uncertain. In this observational study, we examined the characteristics of PD patients with a residual glomerular filtration rate (GFR) > or =1 ml/min per 1.73 m2 vs those with complete anuria and differentiated factors that predict outcome in the two groups of patients. METHODS: Two hundred and forty-six continuous ambulatory peritoneal dialysis (CAPD) patients (39% being completely anuric) were recruited from a single regional dialysis centre. Assessments of haemodynamic, echocardiographic, nutritional and biochemical parameters and indices of dialysis adequacy were done at study baseline and were related to outcomes. RESULTS: During the prospective follow-up of 30.8+/-13.8 (mean+/-SD) months, 28.0% of patients with residual GFR > or =1 ml/min per 1.73 m2 vs 50.5% of anuric patients had died (P = 0.005). The overall 2 year patient survival was 89.7 and 65.0% for patients with GFR > or =1 ml/min per 1.73 m2 and anuric patients, respectively (P = 0.0012). Compared with patients with GFR > or =1 ml/min per 1.73 m2, anuric patients were dialysed for longer (P<0.001), were more anaemic (P<0.005), and had higher calcium-phosphorus product (P<0.01), higher C-reactive protein (P<0.001), lower serum albumin (P<0.05), greater prevalence of malnutrition according to subjective global assessment (P<0.05) and more severe cardiac hypertrophy (P<0.001) at baseline. Using multivariable Cox regression analysis, serum albumin, left ventricular mass index and residual GFR were significant factors associated with mortality in patients with GFR > or =1 ml/min per 1.73 m2, while increasing age, atherosclerotic vascular disease and higher C-reactive protein were associated with greater mortality in anuric PD patients. CONCLUSIONS: Our study demonstrates more adverse cardiovascular, inflammatory, nutritional and metabolic profiles as well as higher mortality in anuric PD patients. Furthermore, factors associated with mortality are also not equivalent for PD patients with and without RRF, suggesting that patients with and without RRF are qualitatively different.     

Importance of residual renal function in continuous ambulatory peritoneal dialysis: its influence on different parameters of renal replacement treatment.

OBJECTIVE: To study the influence of residual renal function (RRF) on different parameters of the renal substitutive treatment offered by peritoneal dialysis. METHODS: We analyzed the impact of RRF on dialysis dose, nutrition parameters, anemia and phosphocalcic metabolism in 37 patients with end-stage renal disease (ESRD) treated by continuous ambulatory peritoneal dialysis (CAPD). Analytical controls were done every 6 months after an initial assessment at the end of the first month of treatment. Multiple lineal regression models were used as the statistical method to analyze the influence of RRF on different theoretically dependent factors. RRF was calculated as a mean of creatinine and urea clearances. Three observations per patient were used: one at the end of the first month of treatment; a final one at the end of follow-up (mean time 24.2 +/- 11.4 months), and at a mean time between them (13.4 +/- 6.7 months), with a final number of 111 observations. RESULTS: Dialysis dose: RRF was the most important factor in terms of creatinine clearance (r(2) = 0.94; beta = 0.999), KT/V (r(2) = 0. 68; beta = 0.819) and beta(2)-microglobulin levels (r(2) = 0.46; beta = -0.489). Nutrition parameters: RRF was a determinant factor for normalized protein catabolic rate (r(2) = 0.53; beta = 0.471), percent lean body mass (r(2) = 0.45; beta = 0.446) and albumin levels (r(2) = 0.25; beta = 0.229). Anemia: RRF was the most important factor when studying hemoglobin levels (r(2) = 0.28; beta = 0.407). Phosphocalcic metabolism: Between the analyzed factors, RRF was the only one which reached significance on serum phosphate levels (r(2) = 0.19; beta = -0.594). RRF did not show any relationship with either calcium or PTH levels. CONCLUSIONS: Independent of other factors, RRF in CAPD is positively and directly related to dialysis dose, beta(2)-microglobulin levels, nutrition parameters (albumin, normalized protein catabolic rate and percent lean body mass, hemoglobin and serum phosphate levels.