Residual renal function in children on haemodialysis and peritoneal dialysis therapy

Renal Replacement Therapy in Neonates

Acute kidney injury (AKI) is a highly prevalent disease entity in the NICU, affecting nearly one-quarter of critically ill neonates by some reports. Though medical management remains the mainstay in the treatment of AKI, renal replacement therapy (RRT) is indicated when conservative measures are unable to maintain electrolytes, fluid balance, toxins, or waste products within a safe margin. Several modalities of RRT exist for use in neonatal populations, including peritoneal dialysis, hemodialysis, and continuous RRT. It is the aim of this review to introduce each of these RRT modalities, as well as to discuss their technical considerations, benefits, indications, contraindications, and complications.

Preservation of Residual Renal Function in Dialysis Patients: Effects of Dialysis-Technique–Related Factors

Objectives

Residual renal function (RRF) is of paramount importance to dialysis adequacy, morbidity, and mortality, particularly for long-term continuous ambulatory peritoneal dialysis (CAPD) patients. Residual renal function seems to be better preserved in patients on CAPD than in hemodialysis (HD) patients. We analyzed RRF in 45 patients with end-stage renal disease (ESRD), commencing either CAPD or HD, to prospectively define the time course of the decline in RRF, and to evaluate dialysis-technique–related factors such as cardiovascular stability and bioincompatibility.

Study Design

Single-center prospective investigation in parallel design with matched pairs.

Materials

Fifteen patients starting CAPD and 15 matched pairs of patients commencing HD were matched according to cause of renal failure and RRF. Hemodialysis patients were assigned to two dialyzer membranes differing markedly in their potential to activate complement and cells (bioincompatibility). Fifteen patients were treated exclusively with the cuprophane membrane (bioincompatible) and the other 15 patients received HD with the high-flux polysulfone membrane (biocompatible).

Measurements

Residual renal function was determined at initiation of dialytic therapy and after 6, 12, and 24 months. Dry weight (by chest x ray and diameter of the vena cava) was closely recorded throughout the study, and the number of hypotensive episodes counted.

Results

Residual renal function declined in both CAPD and HD patients, although this decline was faster in HD patients (2.8 mL/minute after 6 months and 3.7 mL/min after 12 months) than in CAPD patients (0.6 mL/min and 1.4 mL/ min after 6 and 12 months respectively). It declined faster in patients with bioincompatible than with biocompatible HD membranes (3.6 mL/min vs 1.9 mL/min after 6 months). Eleven percent of the HD sessions were complicated by clinically relevant blood pressure reductions, but there were no differences between the two dialyzer membrane groups. None of the CAPD patients had documented hypotensive episodes. None of the study patients suffered severe illness or received nephrotoxic antibiotics or radiocontrast media.

Conclusions

The better preservation of RRF in stable CAPD patients corresponded with greater cardiovascular stability compared to HD patients, independently of the membrane used. Furthermore, there was a significantly higher preservation of RRF in HD patients on polysulfone versus cuprophane membranes, indicating an additional effect of biocompatibility, such as less generation of nephrotoxic substances by the membrane. Thus, starting ESRD patients on HD prior to elective CAPD should be avoided for better preservation of RRF.

Improvement in Clinical Outcome by Early Nephrology Referral in Type Ii Diabetics on Maintenance Peritoneal Dialysis

← Objectives

To evaluate the influence of early nephrology referral on clinical outcome in type II diabetes mellitus patients on maintenance peritoneal dialysis (PD).

← Design

This is a retrospective study in a single University Hospital in Taiwan.

← Patients

This study analyzed the type II diabetic patients entering our PD program from February 1988 to June 2000. Patients that were presented to a nephrologist more than 6 months before starting dialysis were defined as early referrals (ER). Patients were considered late referrals (LR) if they were transferred to the nephrology department within 6 months before initial dialysis.

← Main Outcome Measures

Patient survival and technique survival curves were derived from Kaplan–Meier analysis and were compared using the Cox–Mantel log rank test. Covariates were analyzed with Cox proportional hazards model.

← Results

52 type II diabetic patients were enrolled in this study: 16 in the ER group and 36 in the LR group. Patient survival was better in the ER group than in the LR group {relative risks [exp(coef)] 0.42; 95% confidence interval 0.152 – 0.666; p < 0.05}. The improved survival in the ER group was independent of age at dialysis, good glycemic control, and residual renal function, as indicated in the multivariate analysis with stepwise regression by Cox proportional hazards model. The ER group was also associated with better technique survival.

← Conclusions

These results suggest that early nephrology referral before initiating dialysis is associated with improved long-term clinical outcome in type II diabetics on maintenance PD.

Rate of Decline of Residual Renal Function in Patients on Continuous Peritoneal Dialysis and Factors Affecting It

Objective

We analyzed residual renal function (RRF) in a large number of new peritoneal dialysis (PD) patients to prospectively define the time course of decline of RRF and to evaluate the risk factors assumed to be associated with faster decline.

Study Design

Single-center, prospective cohort study.

Setting

Home PD unit of a tertiary care University Hospital.

Patients

The study included 242 patients starting continuous PD between January 1994 and December 1997, with a minimum follow-up of 6 months and at least three measurements of RRF.

Measurement

All patients had data on demographic and laboratory variables, episodes of peritonitis and the use of aminoglycoside (AG) antibiotics, temporary hemodialysis, and number of radiocontrast studies. Adequacy of PD was measured from 24-hour urine and dialysate collection and peritoneal equilibration test using standard methodology. Further data on RRF was collected every 3 to 4 months until the patient became anuric (urine volume < 100 mL/day or creatinine clearance < 1.0 mL/min) or until the end of study in December 1998.

Outcome Measure

The slope of the decline of residual glomerular filtration rate (GFR) (an average of renal urea and creatinine clearance) was the main outcome measure. Risk factors associated with faster decline were evaluated by a comparative analysis between patients in the highest and the lowest quartiles of the slopes of GFR, and a multivariate analysis using a stepwise option within linear regression and general linear models.

Results

There was a gradual deterioration of residual GFR with time on PD, with 40% of patients developing anuria at a mean of 20 months after the initiation of PD. On multivariate analysis, use of a larger volume of dialysate ( p = 0.0001), higher rate of peritonitis ( p = 0.0005), higher use of AG ( p = 0.0006), presence of diabetes mellitus ( p = 0.005), larger body mass index (BMI) ( p = 0.01), and no use of antihypertensive medications ( p = 0.04) independently predicted the steep slope of residual GFR. Male gender, higher grades of left ventricular dysfunction, and higher 24-hour proteinuria were associated with faster decline on univariate analysis only.

Conclusion

Faster decline of residual GFR corresponds with male gender, large BMI, presence of diabetes mellitus, higher grades of congestive heart failure, and higher 24-hour proteinuria. Higher rate of peritonitis and use of AG for the treatment of peritonitis is also associated independently with faster decline of residual GFR. Whether the type of PD (CAPD vs CCPD/NIPD) is associated with faster decline of residual GFR remains speculative.

Peritoneal Dialysis Case Forum

The Trials and Tribulations of an Adolescent Patient with End-Stage Renal Disease

Risk factors for loss of residual renal function in children with end-stage renal disease undergoing automatic peritoneal dialysis

BACKGROUND

This study analysed children with end-stage renal disease treated with automated peritoneal dialysis (APD) in our centre to explore the risk factors associated with residual renal function (RRF) loss.

METHODS

Children treated with APD as the initial renal replacement therapy regimen from January 2008 to December 2016 were included. All the children had a daily urine volume of ≥100 ml/m² when APD was initiated and a dialysis follow-up time of ≥12 months. A daily urine volume of <100 ml/m² after 12 months of APD treatment was defined as loss of RRF. Possible risk factors that may be associated with RRF loss were analysed.

RESULTS

A total of 66 children were included in the study. After 12 months of APD treatment, the daily urine volume decreased by 377.45 ± 348.80 ml/m², the residual glomerular filtration rate decreased by 6.39 ± 3.69 ml/min/1.73 m² and 29 of the patients (43.9%) developed RRF loss. The higher risk of RRF loss after 1 year of APD treatment was most pronounced in patients with daily urine volume of ≤400 ml/m² before treatment, higher glucose exposure and higher ultrafiltration volume, while the lower risk of RRF loss was in patients with administration of diuretics. Each increase of 1 g/m²/day glucose exposure was associated with a 5% increase in RRF loss (odds ratio (OR) 1.05, p = 0.023) and each increase of 1 ml/m²/day ultrafiltration volume was associated with a 1% increase in RRF loss (OR 1.01, p = 0.013).

CONCLUSION

In children undergoing APD, the risk for loss of RRF is associated with low urine volume at the start of APD, high glucose loading and high peritoneal ultrafiltration volume, while preservation of RRF is associated with the usage of diuretics.

Prescribing peritoneal dialysis for high-quality care in children

Background:

Peritoneal dialysis (PD) remains the most widely used modality for chronic dialysis in children, particularly in younger children and in lower and middle income countries (LMICs). We present guidelines for dialysis initiation, modality selection, small solute clearance, and fluid removal in children on PD. A review of the literature and key studies that support these statements are presented.

Methods:

An extensive Medline search for all publications on PD in children was performed using predefined search criteria.

Results:

High-quality randomized trials in children are scarce and current clinical practice largely relies on data extrapolated from adult studies or drawn from observational cohort studies in children. The evidence and strength of the recommendation is GRADE-ed, but in the absence of high-quality evidence, the opinion of the authors is provided and must be carefully considered by the treating physician, and adapted to local expertise and individual patient needs as appropriate. We discuss the timing of dialysis initiation, factors to be considered when selecting a dialysis modality, the assessment and management of volume status on PD, achieving optimal small solute clearance, and the importance of preserving residual kidney function. While optimal dialysis must remain the goal for every patient, a careful discussion with fully informed patients and caregivers is important to understand the patient and family’s expectations of dialysis and reasonable adjustments to the dialysis program may be considered in accordance with a philosophy of shared decision-making.

Conclusions:

There continues to be very poor evidence in the field of chronic PD in children and these recommendations can at best serve to guide clinical decision-making. In LMICs, every effort should be made to conform to the framework of these statements, taking into account resource limitations.

Higher eGFR at Dialysis Initiation Is Not Associated with a Survival Benefit in Children

BACKGROUND

Study findings suggest that initiating dialysis at a higher eGFR level in adults with ESRD does not improve survival. It is less clear whether starting dialysis at a higher eGFR is associated with a survival benefit in children with CKD.

METHODS

To investigate this issue, we performed a retrospective cohort study of pediatric patients aged 1-18 years who, according to the US Renal Data System, started dialysis between 1995 and 2015. The primary predictor was eGFR at the time of dialysis initiation, categorized as higher (eGFR>10 ml/min per 1.73 m²) versus lower eGFR (eGFR≤10 ml/min per 1.73 m²).

RESULTS

Of 15,170 children, 4327 (29%) had a higher eGFR (median eGFR, 12.8 ml/min per 1.73 m²) at dialysis initiation. Compared with children with a lower eGFR (median eGFR, 6.5 ml/min per 1.73 m²), those with a higher eGFR at dialysis initiation were more often white, girls, underweight or obese, and more likely to have GN as the cause of ESRD. The risk of death was 1.36 times higher (95% confidence interval, 1.24 to 1.50) among children with a higher (versus lower) eGFR at dialysis initiation. The association between timing of dialysis and survival differed by treatment modality-hemodialysis versus peritoneal dialysis (P<0.001 for interaction)-and was stronger among children initially treated with hemodialysis (hazard ratio, 1.56, 95% confidence interval, 1.39 to 1.75; versus hazard ratio, 1.07, 95% confidence interval, 0.91 to 1.25; respectively).

CONCLUSIONS

In children with ESRD, a higher eGFR at dialysis initiation is associated with lower survival, particularly among children whose initial treatment modality is hemodialysis.

Care of the Pediatric Patient on Chronic Dialysis

Optimal care of the pediatric end-stage renal disease (ESRD) patient on chronic dialysis is complex and requires multidisciplinary care as well as patient/caregiver involvement. The dialysis team, along with the family and patient, should all play a role in choosing the dialysis modality which best meets the patient's needs, taking into account special considerations and management issues that may be particularly pertinent to children who receive peritoneal dialysis or hemodialysis. Meticulous attention to dialysis adequacy in terms of solute and fluid removal, as well as to a variety of clinical manifestations of ESRD, including anemia, growth and nutrition, chronic kidney disease-mineral bone disorder, cardiovascular health, and neurocognitive development, is essential. This review highlights current recommendations and advances in the care of children on dialysis with a particular focus on preventive measures to minimize ESRD-associated morbidity and mortality. Advances in dialysis care and prevention of complications related to ESRD and dialysis have led to better survival for pediatric patients on dialysis.

Effect of center practices on the choice of the first dialysis modality for children and young adults

BACKGROUND

Peritoneal dialysis (PD) remains the modality of choice in children, but there is no clear evidence to support a better outcome in children treated with PD. We aimed to assess factors that have an impact on the choice of dialysis modality in children and young adults in France and sought to determine the roles of medical factors and center practices.

METHODS

We included all patients aged <20 years at the start of renal replacement therapy (RRT), recorded in the French RRT Registry between 2002 and 2013. Hierarchical logistic regression models were used to study the association between the patient/center characteristics and the probability of receiving PD as the first dialysis modality.

RESULTS

We included 806 patients starting RRT in 177 centers, 23 of which were specialized pediatric centers. Six hundred and one patients (74.6 %) started with hemodialysis (HD), whereas 205 (25.4 %) started with PD. A greater probability of PD was found in younger children, whereas starting the treatment in an emergency setting was associated with a low use of PD. We found a significant variability among centers that accounted for 43 % of the total variability. The probability of PD was higher in adult centers and was proportional to the rate of PD in the center.

CONCLUSIONS

Center practices are a major factor in the choice of dialysis modality. This raises concerns about patient and family choices and to what extent doctors may influence the final decision. Further pediatric studies focusing on children's and parents' wishes are needed to provide care as close as possible to patients' and families' expectations.

Infants Requiring Maintenance Dialysis: Outcomes of Hemodialysis and Peritoneal Dialysis

BACKGROUND

The impact of different dialysis modalities on clinical outcomes has not been explored in young infants with chronic kidney failure.

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

Data were extracted from the ESPN/ERA-EDTA Registry. This analysis included 1,063 infants 12 months or younger who initiated dialysis therapy in 1991 to 2013.

FACTOR

Type of dialysis modality.

OUTCOMES & MEASUREMENTS

Differences between infants treated with peritoneal dialysis (PD) or hemodialysis (HD) in patient survival, technique survival, and access to kidney transplantation were examined using Cox regression analysis while adjusting for age at dialysis therapy initiation, sex, underlying kidney disease, and country of residence.

RESULTS

917 infants initiated dialysis therapy on PD, and 146, on HD. Median age at dialysis therapy initiation was 4.5 (IQR, 0.7-7.9) months, and median body weight was 5.7 (IQR, 3.7-7.5) kg. Although the groups were homogeneous regarding age and sex, infants treated with PD more often had congenital anomalies of the kidney and urinary tract (CAKUT; 48% vs 27%), whereas those on HD therapy more frequently had metabolic disorders (12% vs 4%). Risk factors for death were younger age at dialysis therapy initiation (HR per each 1-month later initiation, 0.95; 95% CI, 0.90-0.97) and non-CAKUT cause of chronic kidney failure (HR, 1.49; 95% CI, 1.08-2.04). Mortality risk and likelihood of transplantation were equal in PD and HD patients, whereas HD patients had a higher risk for changing dialysis treatment (adjusted HR, 1.64; 95% CI, 1.17-2.31).

LIMITATIONS

Inability to control for unmeasured confounders not included in the Registry database and missing data (ie, comorbid conditions). Low statistical power because of relatively small number of participants.

CONCLUSIONS

Despite a widespread preconception that HD should be reserved for cases in which PD is not feasible, in Europe, we found 1 in 8 infants in need of maintenance dialysis to be initiated on HD therapy. Patient characteristics at dialysis therapy initiation, prospective survival, and time to transplantation were very similar for infants initiated on PD or HD therapy.

Chronic haemodialysis in small children: a retrospective study of the Italian Pediatric Dialysis Registry

BACKGROUND

Chronic haemodialysis (HD) in small children has not been adequately investigated.

METHODS

This was a retrospective investigation of the use of chronic HD in 21 children aged  <2 years (n = 12 aged <1 year) who were registered in the Italian Pediatric Dialysis Registry. Data collected over a period of >10 years were analysed.

RESULTS

The median age of the 21 children at start of HD was 11.4 [interquartile range (IQR) 6.2-14.6] months, and HD consisted mainly of haemodiafiltration for 3-4 h in  ≥4 sessions/week. A total of 51 central venous catheters were placed, and the median survival of tunnelled and temporary lines was 349 and 31 days, respectively (p  < 0.001). Eight children (38 %) showed evidence of central vein thrombosis. Although 19 % of patients received growth hormone and 63.6 % received enteral feeding, the weight and height of these patients remained suboptimal. During the HD period the haemoglobin level increased in all patients, but not to normal levels (from 8.5 to 9.6 g/dl) despite erythropoietin administration (503-600 U/kg/week). The hospitalisation rate was 1.94/patient-year. Seventeen patients underwent renal transplantation at a median age of 3.0 years. Four patients, all affected by severe comorbidities, died during follow-up (in 2 cases due to absence of a vascular access). The 5- and 10-year cumulative survival was 82.4 and 68.7 %, respectively.

CONCLUSIONS

Extracorporeal dialysis is feasible in children aged  <2 years, but comorbidities, vascular access, growth and anaemia remain major concerns.

Risk factors for loss of residual renal function in children treated with chronic peritoneal dialysis

In dialyzed patients, preservation of residual renal function is associated with better survival, lower morbidity, and greater quality of life. To analyze the evolution of residual diuresis over time, we prospectively monitored urine output in 401 pediatric patients in the global IPPN registry who commenced peritoneal dialysis (PD) with significant residual renal function. Associations of patient characteristics and time-variant covariates with daily urine output and the risk of developing oligoanuria (under 100 ml/m²/day) were analyzed by mixed linear modeling and Cox regression analysis including time-varying covariates. With an average loss of daily urine volume of 130 ml/m² per year, median time to oligoanuria was 48 months. Residual diuresis significantly subsided more rapidly in children with glomerulopathies, lower diuresis at start of PD, high ultrafiltration volume, and icodextrin use. Administration of diuretics significantly reduced oligoanuria risk, whereas the prescription of renin–angiotensin system antagonists significantly increased the risk oligoanuria. Urine output on PD was significantly associated in a negative manner with glomerulopathies (−584 ml/m²) and marginally with the use of icodextrin (−179 ml/m²) but positively associated with the use of biocompatible PD fluid (+111 ml/m²). Children in both Asia and North America had consistently lower urine output compared with those in Europe perhaps due to regional variances in therapy. Thus, in children undergoing PD, residual renal function depends strongly on the cause of underlying kidney disease and may be modifiable by diuretic therapy, peritoneal ultrafiltration, and choice of PD fluid.

Strategies for the preservation of residual renal function in pediatric dialysis patients

In adults with end-stage renal disease (ESRD), the preservation of residual renal function (RRF) has been shown to be associated with decreased mortality and improved control of complications of chronic kidney disease. However, less is known on the benefits of RRF in the pediatric dialysis population. The purpose of this article is to review the clinical significance of RRF and to discuss strategies for the preservation of RRF in children with ESRD.

Residual renal function in children treated with chronic peritoneal dialysis

Residual renal function (RRF) in patients with end-stage renal disease (ESRD) receiving renal replacement therapy is defined as the ability of native kidneys to eliminate water and uremic toxins. Preserved RRF improves survival and quality of life in adult ESRD patients treated with peritoneal dialysis. In children, RRF was shown not only to help preserve adequacy of renal replacement therapy but also to accelerate growth rate, improve nutrition and blood pressure control, reduce the risk of adverse myocardial changes, facilitate treatment of anemia and calcium-phosphorus balance abnormalities, and result in reduced serum and dialysate fluid levels of advanced glycation end-products. Factors contributing to RRF loss in children treated with peritoneal dialysis include the underlying renal disease such as hemolytic-uremic syndrome and hereditary nephropathy, small urine volume, severe proteinuria at the initiation of renal replacement therapy, and hypertension. Several approaches can be suggested to decrease the rate of RRF loss in pediatric patients treated with chronic peritoneal dialysis: potentially nephrotoxic drugs (e.g., aminoglycosides), episodes of hypotension, and uncontrolled hypertension should be avoided, urinary tract infections should be treated promptly, and loop diuretics may be used to increase salt and water excretion.

Predictors and consequences of higher estimated glomerular filtration rate at dialysis initiation

There have been no studies in pediatric dialysis patients to evaluate the impact of higher estimated glomerular filtration rate (eGFR) at dialysis initiation on clinical outcomes. Baseline clinical and demographic information was collected for children aged 1-18 years undergoing incident dialysis from 1995-2002 within the United States Renal Data System. Baseline eGFRs calculated by the Schwartz formula were categorized as high (>15 ml/min/1.73 m(2)) or low (< or = 15 ml/min/1.73 m(2)). We determined predictors of eGFR at baseline, and associations between baseline eGFR and subsequent hospitalization for hypertension (HTN) or pulmonary edema (PE) in a longitudinal nonconcurrent pediatric end-stage renal disease (ESRD) cohort. Twenty percent of children had a high eGFR at initiation. Black children were less likely to initiate dialysis with a high eGFR [adjusted odds ratio (adjOR) 0.71, p < 0.001]. Girls were less likely to have a high eGFR at baseline (adjOR 0.71, p < 0.001). Children who received predialysis erythropoietin therapy were more likely to start dialysis with a high eGFR (adjOR 6.67, p < 0.001). Children with higher baseline eGFR were found to have a 21% decreased risk of hospitalization [adjusted hazard ratio (HR) 0.79, 95% confidence interval (CI) 0.65-0.96, p = 0.02]. It is not known whether this clinical benefit will result in decreased mortality and complication rates from cardiovascular disease.

Residual renal function and nutrition in young patients on chronic hemodialysis

Residual renal function (RRF) has been associated with a better nutritional status in adult patients on chronic dialysis, but there is as yet no data available for young patients on chronic hemodialysis (HD). We have retrospectively analyzed 3-day dietary reports and simultaneous urea kinetic monitoring data (n = 179) of 30 children, adolescents and young adults on chronic HD. The protein catabolic rate (PCR) was calculated and normalized by body weight (nPCR). The HD dialysis dose (Kt/VHD), RRF (calculated by urea clearance, Ku, and expressed as residual Kt/V) and total Kt/V (Kt/Vtot) were evaluated. In all patients, nPCR was correlated with dietary protein intake (nDPI) (p < 0.0001) and Kt/Vtot (p < 0.0001) but not with Kt/VHD (p = 0.11). In patients with RRF, Ku was associated with nPCR (p < 0.0001), while Kt/VHD was not (p = 0.10), and nPCR was higher than in patients without RRF (1.46 +/- 0.41 vs. 1.03 +/- 0.33 g/kg/day; p < 0.0001). Patients on recombinant growth hormone (rhGH) treatment showed higher nPCR values than those without rhGH (1.34 +/- 0.41 vs. 1.01 +/- 0.39 g/kg/day; p < 0.0001). In a multiple regression model including age, rhGH treatment, RRF, Kt/Vtot and Kt/VHD, and nPCR showed the best correlation with RRF (beta = 0.128; p < 0.0001). In conclusion, in children, adolescents and young adults on chronic HD treatment, RRF positively affects nutrition independently of HD efficiency and rhGH treatment.

Growth of prepubertal children on dialysis

Growth failure is a common and significant clinical problem for children on dialysis and often remains a major impediment to their rehabilitation. Early referral to a paediatric nephrology centre and appropriate management before the initiation of dialysis may significantly prevent growth deterioration. Growth in children on dialysis can be affected by nutritional, metabolic, and hormonal changes. Early diagnosis of malnutrition and aggressive management should be a priority. Gastrostomy feeding should be used when adequate oral intake to maintain normal height and weight velocity cannot be achieved. Active vitamin D metabolites should be used carefully, to prevent low-turnover bone disease. All children should have an adequate regimen of dialysis and an appropriate management of malnutrition, renal osteodystrophy, metabolic acidosis, salt wasting and anaemia, before recombinant human growth hormone (rhGH) administration is considered. The current challenge of reversing growth impairment in children on dialysis can only be achieved by optimization of their care.

Hemodialysis in children: general practical guidelines

Over the past 20 years children have benefited from major improvements in both technology and clinical management of dialysis. Morbidity during dialysis sessions has decreased with seizures being exceptional and hypotensive episodes rare. Pain and discomfort have been reduced with the use of chronic internal jugular venous catheters and anesthetic creams for fistula puncture. Non-invasive technologies to assess patient target dry weight and access flow can significantly reduce patient morbidity and health care costs. The development of urea kinetic modeling enables calculation of the dialysis dose delivery, Kt/V, and an indirect assessment of the intake. Nutritional assessment and support are of major importance for the growing child. Even if the validity of these "urea only" data is questioned, their analysis provides information useful for follow-up. Newer machines provide more precise control of ultrafiltration by volumetric assessment and continuous blood volume monitoring during dialysis sessions. Buffered bicarbonate solutions are now standard and more biocompatible synthetic membranes and specific small size material dialyzers and tubing have been developed for young infants. More recently, the concept of "ultrapure" dialysate, i.e. free from microbiological contamination and endotoxins, has developed. This will enable the use of hemodiafiltration, especially with the on-line option, which has many theoretical advantages and should be considered in the case of maximum/optimum dialysis need. Although the optimum dialysis dose requirement for children remains uncertain, reports of longer duration and/or daily dialysis show they are more effective for phosphate control than conventional hemodialysis and should be considered at least for some high-risk patients with cardiovascular impairment. In children hemodialysis has to be individualized and viewed as an "integrated therapy" considering their long-term exposure to chronic renal failure treatment. Dialysis is seen only as a temporary measure for children compared with renal transplantation because this enables the best chance of rehabilitation in terms of educational and psychosocial functioning. In long term chronic dialysis, however, the highest standards should be applied to these children to preserve their future "cardiovascular life" which might include more dialysis time and on-line hemodiafiltration with synthetic high flux membranes if we are able to improve on the rather restricted concept of small-solute urea dialysis clearance.

Current and future modalities for functional renal replacement

Approximately 310,000 Americans suffer from end-stage renal disease, with more than 70,000 new cases reported each year. Advances in immunosuppressive therapy for transplanted patients, in addition to the refined care of patients who are dependent on dialysis, have led to an improved survival for patients with renal failure. Structural, molecular, and pharmacologic developments continue to enhance the efficacy and safety of dialysis in the future. In addition, progressive improvements in the past 2 decades in organ transplantation, a greater insight into the immunobiology of graft rejection, and better surgical and medical management have resulted in improved outcomes. Although renal xenotransplantation is still in its early stages of development, additional research is leading this technology forward. Recent successes in harvesting and expanding renal cells in vitro and the development of biologically active synthetic materials allow for the creation of three-dimensional functioning renal units, which, in the future, may be applied ex vivo or in vivo for partial or full replacement of kidney function.

Improved preservation of residual renal function in chronic hemodialysis patients using polysulfone dialyzers

Our objective was to determine whether patients with chronic renal failure requiring maintenance hemodialysis retain intrinsic renal function longer when using reprocessed polysulfone (PS) membrane hemodialyzers or single-use cellulose acetate (CA) membrane hemodialyzers. Fifty consecutive patients with residual renal function (urea clearance > 2.0 mL/min) using PS dialyzers were compared with a retrospective, disease- and time-matched population of patients using CA dialyzers. Endogenous urea clearance was measured every 3 months in all patients with remaining residual function. Other data collected included age, sex, cause of chronic renal failure, use of angiotensin-converting enzyme inhibitors or calcium channel blockers, and hemodynamic stability during hemodialysis. All patients were observed for at least 6 months while using a single type of dialyzer. Study end points included loss of residual renal function (urea clearance < 1.0 mL/min), death, transplant, transfer to peritoneal dialysis, or change of dialyzer. The PS and CA groups of patients were well matched for sex, age, initial renal clearance, predialysis blood pressure, and hemodynamic stability during hemodialysis. The PS patients had a higher delivered Kt/V (1.34 +/- 0.30 [mean +/- SD]) than the CA patients (1.06 +/- 0.20). The PS group had a higher average urea clearance than the CA group after 4 to 9 months of dialysis (2.8 +/- 2.6 mL/min v 1.7 +/- 1.6 mL/min, respectively), after 10 to 15 months of chronic dialysis (2.0 +/- 2.4 mL/min v 1.1 +/- 1.5 mL/min, respectively), and after 16 to 21 months of dialysis (1.3 +/- 1.9 mL/min v 0.5 +/- 1.1 mL/min, respectively; all P < 0.03, t-test). After 22 to 24 months of dialysis, the difference between the two groups was not significant. When comparing patients with identical causes of chronic renal failure, there were no differences between the PS and CA groups for those with diabetes mellitus, tubulointerstitial disease, or polycystic disease. Patients with parenchymal renal disease (glomerulonephritis or nephrosclerosis) had markedly better retention of intrinsic renal function with PS than with CA dialyzers (all P < 0.01). Kaplan-Meier analysis for retention of intrinsic renal function showed that PS patients with parenchymal renal disease had a mean of 23 months before loss of intrinsic renal function, whereas for CA patients the mean was 11 months before loss of intrinsic renal function (P = 0.0005). Cellulose acetate patients lost renal function at an average rate of 0.27 +/- 0.22 mL/min/mo, whereas for PS patients the rate was 0.14 +/- 0.56 mL/min/mo (P = 0.06, rank sum). CA patients with parenchymal renal disease lost renal function at a rate of 0.29 +/- 0.22 mL/min/mo, whereas for PS patients the rate was 0.0 +/- 0.8 mL/min/mo (P = 0.004, rank sum). Age, sex, and the use of either angiotensin-converting enzyme inhibitors or calcium channel blockers did not have an effect on the loss of intrinsic renal function. Patients with nondiabetic parenchymal renal disease receiving chronic hemodialysis with hydrogen peroxide/peroxyacetic acid-reprocessed PS dialyzers and a higher Kt/V lose residual renal function at a slower rate than disease-matched patients using single-use CA dialyzers. Our findings provide further evidence that the choice of dialyzer membrane may have an effect on intrinsic renal function.