Peritoneal transport properties and dialysis dose affect growth and nutritional status in children on chronic peritoneal dialysis. Mid-European Pediatric Peritoneal Dialysis Study Group

Outcomes of Maintenance Peritoneal Dialysis in Children: A State Hospital Experience from Southeastern Turkey

This study aimed to evaluate the clinical features, laboratory features, and outcomes of pediatric patients on peritoneal dialysis (PD) and compare the factors affecting mortality. The demographic, clinical, and laboratory data of 50 patients on maintenance PD followed up for more than 3 months were retrospectively analyzed for non-survivors and survivors to evaluate all factors affecting mortality. The patients (26 boys and 24 girls) had a mean age of 85.4 ± 58.7 months (range: 1-194 months) at the initiation of PD. The mean duration of dialysis at follow-up was 27.8 ± 21.7 months (range: 3-115 months). The rate of peritonitis was one episode per 27.27 patient months. PD was discontinued because of transplantation in eight patients, death in eight patients, and shifting to hemodialysis in three patients. In the Kaplan-Meier analysis, the 1-year patient survival rate at 1 year, 2 years, and 5 years was 81.8%, 51.7%, and 12.3%, respectively. Non-survivors were significantly younger at the start of kidney replacement therapy, had a final younger age at dialysis, and had lower albumin levels than survivors. We excluded four patients with a follow-up period of <6 months. Cox regression analysis revealed a low albumin status (P = 0.014, hazard ratio: 0.230) and a high level of ferritin (P = 0.002, hazard ratio: 1.002) to be risk factors for mortality. This study showed a high mortality rate. Hypoalbuminemia, a younger age at the start of kidney replacement therapy, and a younger final age at dialysis had a significant association with mortality.

Monitoring dialysis adequacy: history and current practice

Dialysis adequacy for pediatric patients has largely followed the trends in adult dialysis by judging the success or adequacy of peritoneal or hemodialysis with urea kinetic modeling. While this provides a starting point to establish a dose of dialysis, it is clear that urea is only part of the picture. Many clinical parameters and interventions now have been identified that are just as impactful on mortality and morbidly as urea clearance. As such, our concept of adequacy is evolving to include non-urea parameters and assessing the impact that following an "adequate therapy" has on patient lives. As we move to a new era, we consider the impact these therapies have on patients and how it affects the quality of their lives; we must take these factors into consideration to achieve a therapy that is not just adequate, but livable.

Peritoneal dialysis outcomes in patients with nephrotic syndrome: a propensity score-matched cohort study

INTRODUCTION

It is unclear whether patients with end-stage renal disease (ESRD) and nephrotic syndrome (NS) can be treated with peritoneal dialysis (PD).

OBJECTIVES

To investigate the outcomes of PD treatment in ESRD patients with or without NS.

METHODS

In this retrospective cohort study, all incident patients with ESRD and NS who started PD from 1 February 2006 to 31 December 2017, were matched with patients without NS using propensity scores based on age, sex, diabetes mellitus status, and serum albumin.

RESULTS

Fifty-three patients in the NS PD group and 53 matched controls were included. The median survival of the NS PD group was comparable to that of the non-NS PD group. An interaction effect was observed between survival time and baseline NS status. Thus, patients' outcomes within and after 1.5 years were analyzed separately. Both mortality (log-rank test, p= .235) and technique failure (log-rank test, p= .543) rates within 1.5 years in patients with NS were comparable to those of the non-NS group. After 1.5 years, however, the NS status at baseline was associated with lower all-cause mortality (p= .020) and lower technique failure (p= .008) rates in PD patients compared with the non-NS group. The multivariable Cox regression analysis showed that compared with the patients in the non-NS PD group, PD patients with NS had both significantly lower all-cause mortality and lower technique failure rate after adjusting for other factors.

CONCLUSIONS

Our study indicates that PD may be considered as a long-term renal replacement therapy for patients with ESRD and baseline NS.

Adequacy of Peritoneal Dialysis in Children: Consider the Membrane for Optimal Prescription

The peritoneal dialysis (PD) prescription should be adequate before being optimal. The peritoneal membrane is a dynamic dialyzer: the surface area and the vascular area both have recruitment capacity.

At bedside, prescription is based mainly on tolerance of the prescribed fill volume, and therefore a too-small fill volume is often prescribed. A too-small fill volume may lead to a hyperpermeable exchange, with potentially enhanced morbidity—or even mortality—risks. Better understanding of the peritoneal membrane as a dynamic dialysis surface area allows for an individually adapted prescription, which is especially suitable for children on automated PD.

Fill volume should be scaled for body surface area (mL/m2) and, to avoid a hyperpermeable exchange, for a not-too-small amount. Fill volume enhancement should be conducted under clinical control and is best determined by intraperitoneal pressure measurement in centimeters of H2O. In children 2 years of age and older, a peak fill volume of 1400 – 1500 mL/m2 can be prescribed in terms of tolerance, efficiency, and peritoneal membrane recruitment.

Dwell times should be determined individually with respect to two opposing parameters:

• Short dwell times provide adequate small-solute clearance and maintain the crystalloid osmotic gradient (and, thereby, the ultrafiltration capacity).

• Long dwell times enhance phosphate clearance, but can lead to dialysate reabsorption.

The new PD fluids (that is, those free of glucose degradation products, with a neutral pH, and not exclusively lactate-buffered) appear to be the best choice both in terms of membrane recruitment and of preservation of peritoneal vascular hyperperfusion.

Peritoneal Loss of Growth Hormone in Children on Automated Peritoneal Dialysis

Objective

To provide quantitative data regarding the daily dialytic loss of growth hormone (GH) in children on peritoneal dialysis (PD).

Design

Prospective study involving 24-hour dialysate collections on 3 consecutive days in patients with and without recombinant human GH (rhGH) treatment.

Setting

Single-center outpatient PD program.

Patients

Twenty-six children undergoing automated PD (APD): 6 with and 20 without daily rhGH.

Main Outcome Measures

Daily peritoneal losses of GH, α1-, β2-microglobulin, transferrin, and albumin.

Results

The mean (±SEM) daily dialytic GH loss was 2.18 ± 0.62 μg/1.73 m2 per day in rhGH-treated patients and 0.42 ± 0.28 μg/1.73 m2 per day in untreated patients, ( p < 0.05). The intraindividual coefficient of variation of daily GH loss was 65%. The peritoneal loss of GH was positively correlated with that of β2-microglobulin ( r = 0.77, p < 0.001) and α1-microglobulin ( r = 0.51, p < 0.01). The variability in β2-microglobulin and α1-microglobulin elimination, together with the use of rhGH, explained 66% of the total variability of daily GH excretion. In patients without rhGH therapy, the daily peritoneal GH loss was approximately 0.05% of the estimated daily endogenous production rate based on previous estimates in children with end-stage renal failure. In patients on rhGH therapy, less than 0.1% of the injected rhGH dose was eliminated by dialysis.

Conclusion

Peritoneal losses of GH in children on APD account only for a minute fraction of endogenous metabolic clearance, and do not explain the variability of the rhGH treatment response. The assessment of dialytic GH elimination may be used to estimate time-integrated mean plasma GH concentrations, and to monitor rhGH treatment compliance.

Evaluation of Nutritional Status and Factors Related to Malnutrition in Children on CAPD

Objective

The aim of this study was to investigate the nutritional status of children on continuous ambulatory peritoneal dialysis (CAPD) and to relate it to the dose of dialysis and serum levels of inflammatory cytokines and insulin-like growth factor-1 (IGF-1).

Patients

17 CAPD patients (8 girls, 9 boys; mean age 13.1 ± 3.5 years, median 15 years) were included in the study. Anthropometric measurements and serum albumin levels were used in the evaluation of nutritional status. Serum interleukin (IL)-1β, IL-6, tumor necrosis factor α, and IGF-1 levels were determined in all CAPD patients and in a healthy control group. Weekly Kt/V and creatinine clearance (CCr) were measured to determine adequacy of dialysis.

Results

The mean dialysis period was 23.7 ± 15.2 months (median 23 months). Anthropometric measurements and serum albumin level were as follows: height 130.2 ± 15.6 cm, height standard deviation score (HtSDS) -4.2 ± 2.4, body mass index (BMI) 16.3 ± 1.6 kg/m2, body mass index standard deviation score (BMISDS) -0.8 ± 0.9, triceps skinfold thickness (TST) 4.2 ± 1.4 mm, midarm circumference (MAC) 16.21 ± 2.3 cm, upper arm muscle area (AMA) 1799.1 ± 535.7 mm2, upper arm fat area (AFA) 334.5 ± 143 mm2, and serum albumin 3.1 ± 0.7 g/dL. The BMI was above the fifth percentile in all patients; TST and MAC were below the fifth percentile in 14 patients (82.4%) and 10 patients (58.8%) respectively. The AMA was below the fifth percentile in 8 patients; however, the AFA was below the fifth percentile in all patients. Mean serum albumin level was under 3.5 g/dL in 70.5% of the children. We found significant positive correlations between BMI and Kt/V ( r = 0.69, p < 0.01), CCr ( r = 0.64, p < 0.05), and IL-6 ( r = 0.61, p < 0.01). There was an inverse correlation between BMISDS and dialysis period ( r = -0.58, p < 0.05); and between IL-6 and serum albumin ( r = -0.49, p < 0.05). A significant positive correlation between BMISDS and serum IGF-1 level ( r = 0.62, p < 0.01) was noted. We also found a significant positive correlation between serum IGF-1 level and both HtSDS ( r = 0.57, p < 0.05) and TST ( r = 0.52, p < 0.05). Significant positive correlations between AFA and CCr and IGF-1 were also noted (both r = 0.56, p < 0.05).

Conclusion

Although many factors may be responsible for malnutrition and growth retardation, we found that prolonged period of dialysis, inadequate dialysis, and low IGF-1 levels are the most important risk factors in CAPD patients.

Is Growth a Valid Outcome Measure of Dialysis Clearance in Children Undergoing Peritoneal Dialysis?

♦ Objective

Our study evaluated growth as a clinical outcome measure of peritoneal dialysis (PD) adequacy in children with end-stage renal disease (ESRD).

♦ Design

This retrospective single-center study was carried out in our tertiary-care medical center.

♦ Patients

The study enrolled 24 patients who initiated dialysis after January 1, 1995, and who had been on dialysis for a minimum of 1 year.

♦ Results

The weekly mean total [PD + residual renal function (RRF)] creatinine clearance (CCr) and Kt/Vurea were 70.3 ± 18 L per 1.73 m2 and 3.45 ± 0.73, respectively. Of the 24 patients, 12 (50%) were anuric. The mean height standard deviation score (SDS) changed to –1.78 at the end of 1 year from –1.58 at baseline. Catch-up growth (positive Δ height SDS) was observed in 9 patients (37%), 7 of whom (78%) had residual renal function (RRF). In contrast, only 5 of 15 patients (33%) with a negative ΔSDS for height had RRF ( p < 0.025). The mean height SDS in patients with RRF improved to –1.64 from –1.78; in patients without RRF, it worsened to –1.90 from –1.37 ( p = 0.01). While the weekly total Kt/Vurea in patients with RRF (3.53) was similar to that in patients without RRF (3.37, p = 0.6), only the native Kt/Vurea had a significant (but weak) positive correlation with Δheight SDS ( r 2 = 0.17, p = 0.04). In contrast, the total weekly CCr was significantly higher ( p = 0.001) in patients with RRF (81.1 L/1.73 m2) as compared with those without RRF (59.5 L/1.73 m2). However, only the native CCr—and not the dialysis CCr—had a significant (but weak) positive correlation with Δheight SDS ( r 2 = 0.17, p = 0.04).

♦ Conclusions

These preliminary data provide evidence for a correlation between solute clearance and growth, with RRF exerting a significant influence on that outcome. The Kt/Vurea data also appear to contradict the presumed equivalence of PD and native clearance in children with ESRD.

Long-term outcomes in children on chronic continuous ambulatory peritoneal dialysis: a retrospective cohort study from a developing country

BACKGROUND

Peritoneal dialysis (PD) is the preferred modality of dialysis among children with end-stage renal disease.

METHODS

To study the incidence of technique failure and survival among children with end-stage renal disease on continuous ambulatory peritoneal dialysis (CAPD), we included children younger than 18 years of age who commenced and continued PD for more than 3 months as their primary form of dialysis between 1st January 2005 and 31st December 2016. Kaplan-Meier survival analysis was applied to analyze the CAPD outcomes.

RESULTS

A total of 68 Tenckhoff (58 double cuffs, and ten single cuffs) catheters were inserted in 66 patients (mean age 12.3 ± 3.91 years) during the study period. Of the 66 children, 31 (47%) experienced 45 episodes of peritonitis. The total duration on CAPD was 107.58 years with a peritonitis rate of 0.42 episodes per year. Overall, the mean patient survival was 41 (95% confidence interval (CI) 29-54) months, with mean patient survival of 72% at 12 months, declining to 30% at 36 months and then remaining stable until the end of follow-up (106 months). The overall mean technique survival was 55 (95% CI 40-69) months, with mean technique survival of 69% at 12 months, declining to 44% at 36 months and then remaining stable until the end of follow-up (106 months).

CONCLUSION

CAPD is a viable option for end-stage renal disease in children from developing countries with a lack of access to automated PD and pediatric hemodialysis centers.

Effect of hypertension and antihypertensive medications on residual renal function in children treated with chronic peritoneal dialysis

PURPOSE

To evaluate the effect of hypertension (HTN) and antihypertensive medications (AHM) on residual renal function (RRF) in children on CAPD and APD.

MATERIAL/METHODS

We retrospectively evaluated underlying kidney disease, systolic and diastolic blood pressure (SBP/DBP), presence and control of HTN (SBP/DBP≥95th percentile), AHM, RRF (daily diuresis, residual glomerular filtration rate [rGFR]), biochemical parameters, BMI Z-score, and dialysis parameters during 12-month follow-up in 87 children (38 CAPD, 49 APD) aged 10.22±4.31 years. The rate of RRF loss was expressed as absolute and relative [%] reduction.

RESULTS

At baseline, HTN was found in 74.7% patients (CAPD/APD: 84.2%/67.3%, P=0.06), most commonly in HUS and least frequently in CAKUT. The proportion of CAPD/APD patients with poorly controlled HTN was 70.0%/63.3% (P=0.50). Relative daily diuresis loss in children with uncontrolled HTN was higher (P=0.017) compared to children with SBP/DBP <95th percentile. No effect of AHM on the rate of RRF loss was found. In multivariate analysis, absolute daily diuresis loss was related to baseline diuresis (β=-0.30, P<0.001) and proteinuria (β=-0.31, P=0.004); absolute rGFR loss to baseline rGFR (β=-0.73, P<0.001) and glucose load after 12 months (β=-0.36, P=0.02); relative daily diuresis loss to mean BMI Z-score (β=-0.44, P=0.04); and relative rGFR to baseline rGFR (β=-0.37, P<0.001) and SBP percentile (β=-0.21, P=0.045).

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.

Adult height in patients with advanced CKD requiring renal replacement therapy during childhood

BACKGROUND AND OBJECTIVES

Growth and final height are of major concern in children with ESRD. This study sought to describe the distribution of adult height of patients who started renal replacement therapy (RRT) during childhood and to identify determinants of final height in a large cohort of RRT children.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A total of 1612 patients from 20 European countries who started RRT before 19 years of age and reached final height between 1990 and 2011 were included. Linear regression analyses were performed to calculate adjusted mean final height SD score (SDS) and to investigate its potential determinants.

RESULTS

The median final height SDS was -1.65 (median of 168 cm in boys and 155 cm in girls). Fifty-five percent of patients attained an adult height within the normal range. Adjusted for age at start of RRT and primary renal diseases, final height increased significantly over time from -2.06 SDS in children who reached adulthood in 1990-1995 to -1.33 SDS among those reaching adulthood in 2006-2011. Older age at start of RRT, more recent period of start of RRT, cumulative percentage time on a functioning graft, and greater height SDS at initiation of RRT were independently associated with a higher final height SDS. Patients with congenital anomalies of the kidney and urinary tract and metabolic disorders had a lower final height than those with other primary renal diseases.

CONCLUSIONS

Although final height remains suboptimal in children with ESRD, it has consistently improved over time.

Comparative Role of PET and Kt/V Determination in Pediatric Chronic Peritoneal Dialysis

Introduction

Nutritional state and growth are considered as prognostic markers of chronic peritoneal dialysis (PD) adequacy in pediatric patients. The euvolemia, blood pressure control, and metabolic and electrolytic equilibrium are parameters to be achieved by PD treatment.

Objective

To describe the chronic PD prescription parameters of a cohort of pediatric patients and to compare the obtained hemodynamic, antrophometric and adequacy results with those suggested by the literature.

Methods

Retrospective analysis based on clinical records evaluation of 30 pediatric patients undergoing PD for more than 6 months from January 1998 to May 2005.

Results

In the present study, 17/30 (56.7%) were boys. Chronic kidney disease was secondary to uropathy in 66.7% of the cases. The infusion volume was > 1,000 ml/m2 in 9 patients. The peritoneal membrane was characterized as high (27.8%), high-average (33.3%), low-average (22.2%) and low transporter (16.7%). The weekly urea Kt/V was > 2.1 in all the evaluated patients. Blood pressure parameters above the 95th percentile despite the use of antihypertensive medication were observed in 5/30 patients, four of whom with CKD secondary to glomerulopathy. The initial and final Body Mass Index and weight for height ratio were preserved in 83.3% (25/30) patients.

Conclusion

Elevated indexes of small solutes removal are easily attained in pediatric PD patients and do not imply optimal clinical management do not imply optimal climanagement.

Peritoneal dialysis in children with end-stage renal disease

Peritoneal dialysis is the preferred chronic dialysis modality for most children owing to its almost universal applicability and superior compatibility with lifestyle over other modalities. Although technological advances and increasing clinical experience have impacted favorably on patient and technique survival, clinical research in pediatric peritoneal dialysis has been hampered by the low incidence of end-stage renal disease (ESRD) in the pediatric population. To overcome this limitation, several international registries have emerged in the past few years to complement other long-standing registries, which together have provided useful information regarding technique-specific complications and comorbidities associated with ESRD in children undergoing chronic peritoneal dialysis. In this Review, we summarize the most relevant findings from these studies, highlighting the substantial variation in patient conditions, peritoneal dialysis practices and management of comorbidities encountered in different parts of the world.

Peritoneal dialysis in infants and young children

Although end-stage renal disease is rare in infants and young children, its development can be associated with significant morbidity and mortality and only through the provision of experienced, multidisciplinary care can a favorable outcome be anticipated. Peritoneal dialysis is the renal replacement modality of choice for this age group and serves as an essential bridge until successful renal transplantation can occur. In this review, we discuss the practice of peritoneal dialysis in infants including the unique ethical and technical considerations facing pediatric nephrologists and caregivers. In addition, we review current guidelines concerning nutrition, growth, and adequacy, as well as the literature on complications and outcomes.

Peritoneal dialysis tailored to pediatric needs

Consideration of specific pediatric aspects is essential to achieve adequate peritoneal dialysis (PD) treatment in children. These are first of all the rapid growth, in particular during infancy and puberty, which must be accompanied by a positive calcium balance, and the age dependent changes in body composition. The high total body water content and the high ultrafiltration rates required in anuric infants for adequate nutrition predispose to overshooting convective sodium losses and severe hypotension. Tissue fragility and rapid increases in intraabdominal fat mass predispose to hernia and dialysate leaks. Peritoneal equilibration tests should repeatedly been performed to optimize individual dwell time. Intraperitoneal pressure measurements give an objective measure of intraperitoneal filling, which allow for an optimized dwell volume, that is, increased dialysis efficiency without increasing the risk of hernias, leaks, and retrofiltration. We present the concept of adapted PD, that is, the combination of short dwells with low fill volume to promote ultrafiltration and long dwells with a high fill volume to improve purification within one PD session. The use of PD solutions with low glucose degradation product content is recommended in children, but unfortunately still not feasible in many countries.

The short peritoneal equilibration test in pediatric peritoneal dialysis

The peritoneal equilibration test (PET) is the gold standard method for defining peritoneal membrane permeability and for prescribing peritoneal dialysis (PD) therapy on an individual basis. However, it is laborious, consumes nursing time, and requires many hours to be performed. Therefore, several authors have attempted to validate a short PET protocol, with controversial results. To evaluate the concordance between the 2-h (short) and 4-h (classical) peritoneal equilibrium test, a prospective observational protocol was applied in three PD centers (Mexico, Chile, and Uruguay) between July 1, 2008 and July 31 2009. PET protocol: the night prior to the test, each patient received five exchanges, 1 h each, at the same glucose concentration as previously used. Afterwards, a 2.5% glucose dialysis solution was used for a dwell time of 4 h. Exchange fill volume was 1,100 ml/m2 body surface area. The next morning, the 4-h dwell was drained, and Dianeal 2.5% was infused. Three dialysate samples at 0, 2, and 4 h were obtained. A single blood sample was obtained at 120 min. Creatinine D/P and glucose D/D0 ratios were calculated at hours 0, 2, and 4. Patients were categorized as low, low average, high average, or high transporters according creat D/P and gluc D/D0 results. Pearson and Kappa test were used for numerical and categorical correlations, respectively, and p<0.05 was considered significant. Eighty-seven PET studies were evaluated in 74 patients, 33 males, age 11.1+/-5.05 years old. A positive linear correlation of 92% between 2 and 4-h creat D/P and 80% between 2 and 4-h gluc D/D0 (p<0.001) was founded. The Kappa test showed a significant concordance between creat D/P and gluc D/D0 categories at 2 and 4 h (p<0.001). When analyzing cut-off-value categories, creat D/P was founded to be lower and gluc D/D0 higher than other experiences. This multicentric prospective study strongly suggests that PET obtained at 2 h and 4 h, based on either creatinine or glucose transport, provides identical characterization of peritoneal membrane transport capacity in PD children.

Changes in body fat mass in patients after starting peritoneal dialysis

BACKGROUND

Peritoneal dialysis (PD) is characterized by gain in fat mass. Visceral fat mass is associated with metabolic syndrome and atherosclerosis rather than subcutaneous fat mass. In addition, the change in visceral fat mass is a more reliable predictor of survival in PD patients. In this study, we prospectively examined serial changes in fat composition and nutritional status and analyzed factors associated with gain in fat mass in patients undergoing PD.

METHODS

Body composition was assessed by bioelectric impedance analysis (BIA) and computed tomogram (CT). Nutrition status was assessed by Subjective Global Assessment (SGA), protein equivalent of nitrogen appearance (nPNA), serum albumin, C-reactive protein (CRP), and lipid profile. All measurements except BIA were performed on the seventh day and at 6 and 12 months after the start of PD.

RESULTS

60 patients (30 men; mean age 55.0 ± 12.5 years) were enrolled. Increase in body weight continued during the 12 months but visceral and subcutaneous fat mass increased during the first 6 months and decreased during the second 6 months. While hematocrit and serum albumin decreased during the first 6 months, they did not change during the second 6 months. Serum creatinine, total cholesterol, and triglyceride increased similarly to the weight pattern. While nPNA decreased during the 12 months, Kt/V, SGA, and CRP did not change. Patients that had more visceral fat mass at the start of PD had less gain of visceral fat mass during the first 6 months (r = -0.821, p = 0.002). Patients that had more subcutaneous fat mass at the start of PD had less gain of subcutaneous fat mass (r = -0.709, p = 0.015). The change in weight was not associated with the change in visceral or subcutaneous fat during the first 6 months.

CONCLUSION

Patients starting PD experience weight gain, including visceral and subcutaneous fat, during the first 6 months of PD. Patients with high baseline fat mass had less increase in fat mass than those with low baseline fat mass, regardless of visceral or subcutaneous fat mass.

Outcome and risk factors for mortality in pediatric peritoneal dialysis

BACKGROUND

The mortality rate among children requiring renal replacement therapy is higher than in children without end-stage renal disease (ESRD). Some factors, such as hypoalbuminemia, high peritoneal transport rate, age, malnutrition, cardiovascular disease, and recurrent peritonitis, appear to be associated with lower survival in adult peritoneal dialysis patients. Data regarding risk factors of mortality in children with continuous ambulatory peritoneal dialysis (CAPD) are limited. The aims of this study were to analyze the clinical characteristics of patients and investigate if routinely used laboratory and clinical variables are independent risk factors for mortality in children on CAPD.

METHODS

We performed a retrospective chart analysis of pediatric ESRD patients on CAPD between January 1997 and September 2008. 29 patients undergoing CAPD for more than 3 months were enrolled. An analysis was performed on clinical and biochemical variables for survivors and nonsurvivors to identify potential risk factors for mortality.

RESULTS

Mean age was 12.18 +/- 4.57 years. During the follow-up period, 8 patients transferred to hemodialysis and 13 patients received deceased donor renal transplantation. By the end of the study, 5 patients had died. Actuarial survival rate at 2 and 5 years was 96.55% and 91.19% respectively. The major complication during therapy was peritonitis (1 episode/57.79 patient-months). In the univariate analysis, younger age at initiation of dialysis, presence of comorbid disease, higher peritoneal transport rate, increased protein losses through peritoneal dialysis, high total daily protein loss, hypoalbuminemia, and hypophosphatemia were variables associated with mortality in pediatric CAPD patients. However, in the multivariate analysis, only low serum albumin (b = -2.089, p = 0.006; hazard ratio 8.06, 95% confidence interval 0.028 - 0.546) was independently associated with mortality.

CONCLUSION

Mortality was low in our pediatric patients receiving CAPD. Hypoalbuminemia showed a significant association with death in CAPD patients.

Impact of peritoneal transport characteristics on cardiac function in paediatric peritoneal dialysis patients: a Turkish Pediatric Peritoneal Dialysis Study Group (TUPEPD) report

BACKGROUND

The peritoneal equilibration test (PET) is recommended in paediatric peritoneal dialysis (PD) patients to assist prescription management. Despite contradictory reports, high transporter status is associated with reduced survival rate in adults. Since cardiac disease is one of the main causes of mortality in paediatric PD patients, we aimed to evaluate whether transport features have any effect on biochemical data and cardiac function in this group.

METHODS

One hundred and ten PD patients (13 +/- 5 years, PD vintage: 31 +/- 27 months) were enrolled into the study. Four-hour dialysate/plasma creatinine ratio was used for differentiating PET groups. Thirty-eight patients were high transporters, 29 were high-average transporters and 43 were low-average/low transporters. Echocardiography was performed in all subjects.

RESULTS

Age, PD vintage, dialysate glucose concentration, ultrafiltration volume, urine volume and blood pressure levels were similar in all PET groups. No biochemical or echocardiographic data (ejection fraction, fractional shortening, left ventricular mass index, myocardial performance index, power Doppler E/tissue Doppler E ratio reflecting diastolic function) were different among PET groups except lower albumin (P = 0.025) levels in high transporters and higher high-sensitivity C-reactive protein (P = 0.026) levels in high and high-average transporters compared to other transport groups.

CONCLUSIONS

Cardiac structural and functional abnormalities are highly prevalent among paediatric PD patients. Transport rates did not have a significant effect on biochemical parameters or cardiac structural/functional parameters. It might be suggested that being a high transporter does not provide a disadvantage in terms of atherogenic tendency and cardiac disease in paediatric PD patients. Oligoanuria, anaemia and hypertension were independent predictors of cardiac disease.

Simulating inadequate dialysis and its correction using an individualized patient-derived nomogram

Computerized kinetic modeling is a valuable automated peritoneal dialysis (APD) prescription tool for optimizing dialysis adequacy. However, non-compliance results in failure to achieve adequacy targets. The aim of this study was to determine if a nomogram could estimate dialysis compensations for shortfalls in simulated non-compliant patients, such that total weekly urea clearance (Kt/V(urea)) targets are met. Individualized nomograms comprising a series of curves were derived from PD Adequest (ver. 2.0)-predicted Kt/V(urea) data (r (2 ) > 0.99) for different APD prescriptions. The nomogram was then used to estimate the (Nomogram-computed) average of the daily Kt/V(urea) in 14 patients. The study comprised three 1-month phases. Patients were compliant to dialysis in phase I, where Adequest-predicted Kt/V(urea) showed good agreement with both measured (r (I) = 0.72), and Nomogram-computed values (r (I) > 0.99) (p < 0.001). Conversely, in non-compliant phase II, Nomogram-computed values were lower than Adequest-predicted values (p < 0.002). In phase III, the nomogram estimated prescription adjustments required to compensate for shortfalls, such that there was significantly less difference between Nomogram-computed and Adequest-predicted Kt/V(urea) than in phase II (p = 0.005). Thus, despite non-compliance, predicted Kt/V(urea) targets were attained using the nomogram to adjust the daily APD prescriptions. This concept is potentially useful for patients desiring to compensate for inadvertent shortfalls, rather than for 'truly non-compliant' patients.

Selection of modalities, prescription, and technical issues in children on peritoneal dialysis

Peritoneal dialysis (PD) is widely employed as a dialytic therapy for uraemic children, especially in its automated form (APD), that is associated with less burden of care on patient and family than continuous ambulatory PD. Since APD offers a wide range of treatment options, based on intermittent and continuous regimens, prescription can be individualized according to patient's age, body size, residual renal function, nutritional intake, and growth-related metabolic needs. Transport capacity of the peritoneal membrane of each individual patient should be assessed, and regularly monitored, by means of standardized peritoneal function tests validated in pediatric patients. To ensure maximum recruitment of peritoneal exchange area, fill volume should be scaled to body surface area and adapted to each patient, according to clinical tolerance and intraperitoneal pressure. PD solutions should be employed according to their biocompatibility and potential ultrafiltration capacity; new pH-neutral, glucose-free solutions can be used in an integrated way in separate dwells, or by appropriately mixing during the same dialytic session. Kinetic modelling software programs may help in the tailoring of PD prescription to individual patients' characteristics and needs. Owing to advances in the technology of new APD machines, greater programming flexibility, memorized delivery control, and tele-dialysis are currently possible.

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.

Rapid Solute Transport in the Peritoneum: Physiologic and Clinical Consequences

This review focuses on the physiologic and clinical consequences of rapid solute transport in the peritoneum. The concept, the current understanding of related factors, and the possible causes implicated in rapid solute transport are discussed first. Then, the consequences, with particular emphasis on mortality, are highlighted. Finally, based on recent advances and clinical studies, some strategies for the treatment of fast peritoneal transport are reviewed.

Peritoneal dialysis prescription in children: bedside principles for optimal practice

There is no unique optimal peritoneal dialysis prescription for all children, although the goals of ultrafiltration and blood purification are universal. In turn, a better understanding of the physiology of the peritoneal membrane, as a dynamic dialysis membrane with an exchange surface area recruitment capacity and unique permeability characteristics, results in the transition from an empirical prescription process based on clinical experience alone to the potential for a personalized prescription with individually adapted fill volumes and dwell times. In all cases, the prescribed exchange fill volume should be scaled for body surface area (ml/m(2)), and volume enhancement should be conducted based on clinical tolerance and intraperitoneal pressure measurements (IPP; cmH(2)O). The exchange dwell times should be determined individually and adapted to the needs of the patient, with particular attention to phosphate clearance and ultrafiltration capacity. The evolution of residual kidney function and the availability of new, more physiologic, peritoneal dialysis fluids (PDFs) also influence the prescription process. An understanding of all of these principles is integral to the provision of clinically optimal PD.

Short PET in pediatric peritoneal dialysis

Peritoneal equilibration test (PET) is a common technique used in children to evaluate peritoneal membrane transport capacity and adequate the dialysis regimen. Considering that this is a laborious test, a shortened version has been proposed. Our goal was to evaluate the concordance between the 2-h (short) and 4-h (classical) PET values to determine whether the short PET could be used in the clinical setting. Eighty-one PET corresponding to 81 peritoneal dialysis patients from two pediatric nephrology centers were retrospectively analyzed. Peritoneal transport capacity was evaluated using the dialysate to plasma ratio (D/P) of creatinine and the ratio of dialysate glucose to baseline dialysate glucose (D/D(0)) at 2 and 4 h. The mean [+/- standard deviation (SD)] creatinine D/P ratio at 2 and 4 h were 0.41 +/- 0.13 and 0.66 +/- 0.17, respectively, and the mean (+/- SD) D/D(0) glucose were 0.64 +/- 0.11 and 0.39 +/- 0.12 at the same times. Applying McNemar chi(2) test to evaluate the association between the categories obtained at 2 and 4 h, we found no relationship between the 2- and 4-h PET for both D/P and D/D(0) (p > 0.05). These results suggest that the use of this abbreviated test is probably not reliable for estimating the transport capacity of the peritoneal membrane in the pediatric population.

Correlation of metabolic syndrome with residual renal function, solute transport rate and peritoneal solute clearance in chronic peritoneal dialysis patients

BACKGROUND

Metabolic syndrome (MetS) and insulin resistance (IR) strongly promote macrovascular complications and endothelial dysfunction. They accelerate the progression of renal dysfunction in chronic kidney disease patients. However, their correlation with residual renal function (RRF) and peritoneal characteristics have never been investigated.

METHODS

The inter-relationships of IR (homeostatic model assessment, HOMA(IR)), serum adiponectin level, body mass index (BMI), highly sensitive C-reactive protein (hs-CRP), RRF, peritoneal solute clearance (Kt/V(urea)) and solute transport rate of 104 chronic peritoneal dialysis (PD) patients were examined.

RESULTS

Patients with (n = 57) and without (n = 47) clinically diagnosed MetS had the same degree of RRF, peritoneal Kt/V(urea), and solute transport rate. Higher HOMA(IR) (p = 0.011), BMI (p = 0.01) and hs-CRP (p = 0.032), as well as lower adiponectin (p = 0.019), were associated with lower peritoneal Kt/V(urea). Serum adiponectin was negatively associated with solute transport rate (p = 0.02). In multiple regression analysis, higher HOMA(IR) (p = 0.005), BMI (p = 0.021) and hs-CRP (p < 0.001) correlated with lower peritoneal Kt/V(urea).

CONCLUSIONS

MetS plays an important role in both macrovascular complications and endothelial dysfunction in chronic PD patients, which correlates with changes in peritoneal solute clearance and solute transport rate but not RRF.

Nutrition in children with CRF and on dialysis

The objectives of this study are: (1) to understand the importance of nutrition in normal growth; (2) to review the methods of assessing nutritional status; (3) to review the dietary requirements of normal children throughout childhood, including protein, energy, vitamins and minerals; (4) to review recommendations for the nutritional requirements of children with chronic renal failure (CRF) and on dialysis; (5) to review reports of spontaneous nutritional intake in children with CRF and on dialysis; (6) to review the epidemiology of nutritional disturbances in renal disease, including height, weight and body composition; (7) to review the pathological mechanisms underlying poor appetite, abnormal metabolic rate and endocrine disturbances in renal disease; (8) to review the evidence for the benefit of dietetic input, dietary supplementation, nasogastric and gastrostomy feeds and intradialytic nutrition; (9) to review the effect of dialysis adequacy on nutrition; (10) to review the effect of nutrition on outcome.

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.

Advances in renal replacement therapy as a bridge to renal transplantation

While renal transplantation remains the most prevalent treatment for children with end-stage renal disease, the majority of children incident to ESRD receive dialytic therapy prior to receiving a renal allograft and 25% of children are still receiving dialytic therapy 36 months after achieving ESRD. The current review discusses the most recent advancements in both hemodialysis and PD therapies to provide optimal care for children as a bridge until renal transplantation. Areas covered include dialysis dose assessment, target dry weight assessment, vascular access and advancements in PD technology.

Normalized protein catabolic rate versus serum albumin as a nutrition status marker in pediatric patients receiving hemodialysis

BACKGROUND

Protein-energy malnutrition occurs commonly in patients receiving hemodialysis (HD). Although serum albumin (sAlb) is recommended to monitor nutrition status in patients receiving HD, many processes unrelated to nutrition status can affect albumin concentrations.

METHODS

We previously showed normalized protein catabolic rate (nPCR) to be superior to sAlb to reflect improvement in nutrition status in pediatric patients receiving maintenance HD after treatment with intradialytic parenteral nutrition for severe protein-energy malnutrition. We now compare nPCR and sAlb as nutrition status markers for pediatric patients on HD irrespective of current nutrition status.

RESULTS

Forty-four patients comprising 840 months of HD provision were assessed. nPCR was higher for younger patients. Mean nPCR values were significantly lower for adolescent patients with persistent weight loss of at least 2% for at least 3 consecutive months versus patients without persistent weight loss (1.03 +/- 0.29 g/kg/d vs. 1.15 +/- 0.27 g/kg/d, P < .002), and the odds for developing persistent weight loss were four times greater for adolescent patients with nPCR less than 1 g/kg/d. No association between nPCR and weight loss was observed for younger patients. Mean sAlb levels were greater than 4 g/dL for all patient age groups and did not demonstrate a clinically significant difference between patients with or without weight loss.

CONCLUSION

We suggest that nPCR may be useful for monthly nutrition status in adolescent patients receiving maintenance HD and that adolescents with nPCR less than 1 g/kg/d may be at increased risk for subsequent weight loss.

Pro- and Anti-Inflammatory Cytokines in Chronic Pediatric Dialysis Patients: Effect of Aspirin

Dialysis provides effective and safe treatment of ESRD in children, but patients who are maintained on chronic dialysis are at risk for cardiovascular disease. One major risk factor for cardiovascular disease in adult patients with ESRD is chronic inflammation. The effect of anti-inflammatory therapy with aspirin on serum cytokine concentration was studied in seven children who were receiving hemodialysis (HD) and seven who were receiving continuous cycling peritoneal dialysis (CCPD or PD). Dialysis vintage was 4.3 +/- 4.6 yr; single-pool Kt/V was 1.46 +/- 1.4, mean equilibrated Kt/V was 1.27 +/- 0.16, and PD weekly Kt/V was 2.45 +/- 0.30. Baseline proinflammatory cytokine IL-1beta, IL-6, IL-8, and TNF-alpha serum concentrations were significantly elevated, whereas serum anti-inflammatory cytokine IL-4 and IL-10 concentrations were normal. The patterns of cytokine elevation were similar for patients who were receiving HD versus PD. IL-4 and IL-6 concentrations demonstrated strong positive correlation with dialysis vintage (IL-4, P < 0.03; IL-6, P < 0.0001). Pre-aspirin serum cytokine concentrations did not vary with single-pool Kt/V or equilibrated Kt/V for HD patients or with weekly Kt/V for PD patients. Serum IL-8 and TNF-alpha concentrations were significantly reduced by aspirin treatment at 4 mo (P = 0.04 and P = 0.007, respectively). Serum IL-6 concentration decreased with aspirin treatment but not significantly (P = 0.1). Serum IL-1beta concentration remained unchanged, and IL-4 and IL-10 concentrations remained stable throughout aspirin treatment. The effect of aspirin treatment on serum cytokine concentrations was similar for HD and PD patients. In HD patients, IL-6, IL-8, and TNF-alpha remained suppressed 1 mo after discontinuation of aspirin. It is concluded that proinflammatory cytokines are elevated in pediatric HD and PD patients without counterbalance from anti-inflammatory cytokines, and aspirin therapy attenuates inflammation.

Clinical practice guidelines for pediatric peritoneal dialysis

Peritoneal dialysis (PD) continues to be an important modality of treatment for children with end-stage renal disease. The Canadian Association of Pediatric Nephrologists recognized the need nationally to review the literature on the delivery of PD in children to provide optimal standardized care. This resulted in the development of the Canadian Clinical Practice Guidelines for pediatric PD. Clinical practice guidelines are a useful adjunct to clinical care. The present review includes recommendations for catheter placement and types, requirement for prophylactic omentectomy, initiation and adequacy of dialysis, PD prescription, and solute clearance. It provides physicians with updated evidence-based recommendations that include consideration towards practicality with the major goal of improved and standardized patient care.

Peritoneal protein losses in children with steroid-resistant nephrotic syndrome on continuous-cycler peritoneal dialysis

Glomerular protein permeability rises in nephrotic syndrome and may result from the effect of an unidentified "circulating factor." The effect of this "circulating factor" on the permeability of other body membranes is unknown. In this study we examine the peritoneal membrane protein permeability in patients with nephrotic syndrome on chronic-cycler peritoneal dialysis. We conducted a retrospective study of peritoneal protein losses in the dialysate effluent of 60 pediatric peritoneal dialysis patients (ages 5.1-22 years) over a 6-year period (January 1997-December 2002). Nineteen patients had steroid-resistant nephrotic syndrome (SRNS), while 41 had other non-nephrotic etiologies of renal failure. Total and normalized peritoneal protein losses are higher in SRNS than in non-nephrotic patients (12,603+/-5,403 mg/day vs 4,475+/-469 mg/day, P<0.05; 297.8+/-79.3 mg/kg per day vs 156.8+/-16.0 mg/kg per day, P<0.05; 9,614.6+/-3,253.4 mg/m(2) per day vs 4,168.3+/-367.3 mg/m(2) per day, P<0.05). The ratio of total protein in dialysate to plasma, a measure of peritoneal membrane protein permeability, was higher in SRNS patients (3.50+/-1.00% vs 0.68+/-0.06%, P<0.001). Serum albumin concentration was lower in SRNS patients (3.09+/-0.13 mg/dl vs 3.52+/-0.07 mg/dl, P<0.01). There were no differences between the two groups with regard to duration of peritoneal dialysis, dialysis prescription, numbers of peritonitis episodes, catheter replacements, or hospitalizations. In summary, these results demonstrate that peritoneal protein losses in patients with SRNS are twice as great as in those without nephrotic syndrome. These results are consistent with the systemic effect of a "circulating factor" in SRNS and underscore the importance of adequate protein intake in patients on peritoneal dialysis.

The personal dialysis capacity test is superior to the peritoneal equilibration test to discriminate inflammation as the cause of fast transport status in peritoneal dialysis patients

This study evaluated the potential of the Personal Dialysis Capacity (PDC) test to discriminate fast transport status (FTS) as a consequence of inflammation versus FTS because of other causes. This distinction is important because new therapeutic options such as icodextrin and automated peritoneal dialysis can abolish the negative impact on outcome of FTS if fast transport is not caused by inflammation. A PDC test and a Peritoneal Equilibration Test (PET) were performed in 135 incident PD patients. Membrane characteristics were related with baseline biochemical parameters and C-reactive protein. After correction for other covariates, only large pore flux (J(v)L) but not surface area over diffusion distance (A0/dX) or dialysate over plasma concentration was related to C-reactive protein. Using the PDC test for detection of inflammation, positive and negative predictive values were 16/36 and 80/99, respectively, whereas with PET, positive predictive value was 5/20 and negative predictive value 92/115 (chi2 = 0.009). In a Cox regression for patient survival with correction for age, a J(v)L higher than expected by the surface area over diffusion distance, predicted outcome (P = 0.04). Patients with inflammation had a higher J(v)L (0.21 +/- 0.12 versus 0.17 +/- 0.09; P = 0.06) and a lower ultrafiltration (89 +/- 631 versus 386 +/- 601 ml/d; P = 0.06) and urine output (878.45 +/- 533.55 versus 1322 +/- 822 ml/d; P = 0.023) than patients without inflammation. There was no difference for surface area over diffusion distance (A0/dX) or dialysate over plasma concentration. A PDC test yields far more information about the peritoneal membrane characteristics than a PET. A J(v)L higher than expected by the A0/dX is an indicator of inflammation and is related to an increased mortality. The PET is not able to discriminate between FTS because of inflammation versus because of anatomic reasons, whereas the PDC test does.

Risk factors for peritonitis in pediatric peritoneal dialysis: a single-center study

Recent US registry data and a European multicenter study described increased risk of peritonitis in young children on peritoneal dialysis (PD). No underlying age-specific risk factors could be defined in these reports. Therefore, we analyzed risk factors for peritonitis in children treated by PD as primary renal replacement therapy at the Kinderdialyse, Vienna, and particularly searched for age-specific aspects. Thirty children (15 boys, mean age 4.6 years) received PD [21 automated peritoneal dialysis (APD), nine continuous ambulatory peritoneal dialysis (CAPD)] for 13 months (3-49 months). During the total observation period of 395 dialysis months, 27 peritonitis episodes were diagnosed (1:14.6 months or 0.82/patient per year). Of our population, 43% remained peritonitis free; seven patients suffered from more than one peritonitis episode. Ten potential risk factors [age, gender, PD modality, duration of PD, exit-site status, urine volume, residual glomerular filtration rate (GFR), Kt/V, normalized protein catabolic rate (nPCR), albumin] and four indices of peritonitis outcome (peritonitis incidence, peritonitis burden, risk of suffering more than one episode of peritonitis and chance of staying free from peritonitis) were analyzed. Our study identified six risk factors in univariate analysis, namely age, APD treatment, exit-site infections, low urinary volume, low residual GFR and low nPCR, which were significantly correlated with two or more of the outcome indices. Multivariate analysis identified exit-site infection and residual urine volume as strong independent predictors. In summary, our study identified several age-dependent and age-independent risk factors for peritonitis in pediatric PD. These data demonstrate that the risk for peritonitis in small children is not pre-determined but might be open to therapeutic interventions, such as optimizing exit-site care, dialysis prescription and nutrition management.

Middle molecule and small protein removal in children on peritoneal dialysis

BACKGROUND

Dialysis efficiency has a great influence on the outcome of patients. Few data are available on the removal of solutes with molecular weights higher than urea and creatinine. The aim of our study was to assess the transport and the removal of substances with molecular weights up to 15 kD and to evaluate the contribution of residual renal function in peritoneal dialysis (PD) children.

METHODS

Seventeen patients of 12 +/- 4 years undergoing automated PD were studied. Ten patients had 563 +/- 355 mL/day of urine output, and 7 were anuric. During a standardized nightly intermittent PD (NIPD) session, a single-injection inulin clearance was performed. Urea, creatinine, inulin (measured by HPLC), cystatin C and beta2-microglobulin (beta2m) were measured in blood, urine and dialysate. Clearances (L/week/1.73 m2) and weekly solute removal index (SRI) were calculated for all the solutes; weekly Kt/V was calculated for urea.

RESULTS

In non-anuric versus anuric patients the total clearances were: urea 82.6 +/- 18.3 versus 71.3 +/- 26.4; creatinine 82.7 +/- 28.6 versus 47.8 +/- 18.8; inulin 42.8 +/- 11.3 versus 32.8 +/- 20.4; beta2m 14.2 +/- 13.8 versus 9.2 +/- 8.3; cystatin C 20.2 +/- 9.4 versus 9.7 +/- 4.8. In the patients with residual diuresis, the urea was removed mainly by PD (69.2%), while inulin, beta2m and cystatin C were removed by renal clearance (64.0%, 79.5% and 62.8%, respectively). Total, peritoneal and renal weekly Kt/V values in the subjects with residual renal function, were 2.86 +/- 0.70, 1.99 +/- 0.40 and 0.87 +/- 0.43, respectively. Peritoneal weekly Kt/V in the anuric patients was 2.36 +/- 0.85; total weekly Kt/V in the total group was 2.65 +/- 0.78. Weekly SRIs in non-anuric versus anuric patients were: urea 2.56 +/- 0.58 versus 2.09 +/- 0.74; creatinine 2.66 +/- 0.73 versus 1.46 +/- 0.56; inulin 2.36 +/- 0.92 versus 1.64 +/- 1.60; beta2m 1.26 +/- 1.10 versus 1.20 +/- 1.90; cystatin C 1.72 +/- 0.83 versus 1.58 +/- 1.62.

CONCLUSIONS

Solutes removed during PD tend to decrease following an increase in molecular weight of the substance. Since anuric patients are at higher risk of middle molecule and small protein accumulation, more attention should be paid to the removal of middle molecules. Further studies should be undertaken to evaluate whether removing them has a clinical impact and to determine their threshold levels.

Peritoneal dialysis in children: challenges for the new millennium

Advances in technology and experience accumulated over the past 2 decades have resulted in the ability to successfully provide chronic peritoneal dialysis (PD) to children of all ages and sizes. However, many important clinical issues remain, including uncertainty regarding the "optimal" dialysis dose for children, the treatment of growth retardation associated with renal insufficiency, prevention of peritonitis, and the challenge of caring for newborn infants with end-stage renal disease (ESRD). This article summarizes current knowledge in each of these 4 areas, highlighting not only the advances of the past quarter-century, but also the questions that persist as we initiate the new millennium. The outcome of children receiving PD will be markedly improved only when ongoing and future research efforts reveal the optimal solutions to these important issues.