Anuric Peritoneal Dialysis Patients Research Articles

MO682: Serum Total Indoxyl Sulfate is Associated with Intraperitoneal Inflammation and High Peritonitis Episodes in Peritoneal Dialysis Patients

Abstract BACKGROUND AND AIMS The accumulating evidence presented thus far supports the idea that indoxyl sulfate (IS) is a trigger of chronic inflammation in end-stage kidney disease patients. However, although serum IS is one of the most extensively studied uremic toxins, no single study exists which has investigated the association between serum IS and intraperitoneal inflammation in peritoneal dialysis (PD) patients. The present study was undertaken to evaluate the association between serum total IS (tIS) concentration and the pro-inflammatory markers in peritoneal dialysis effluent (PDE) and peritonitis episodes in PD patients. METHOD In this observational cross-sectional study, we analysed serum tIS concentration and 24-h PDE levels of interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein -1 (MCP-1) in 74 PD patients with an average age of 55 (38–64) years and dialysis vintage of 36 (30–58) months. All patients had been undergoing continuous ambulatory PD and had no PD-associated infectious complications for more than 3 months. Serum concentrations of tIS were determined using the spectrophotometry method. The concentrations of IL-6, TNF-α and MCP-1 in PDE were analysed using ELISA. For the statistical analysis, we stratified this PD patient cohort into two groups depending on experienced peritonitis: the peritonitis group (n = 48) and the peritonitis-free group (n = 26). The data were presented as the median and the interquartile ranges [Me (Q25–Q75)] and compared using the Kruskal–Wallis test. The Spearmen correlation test was performed to assess the association between IS and the pro-inflammatory markers. RESULTS Significant differences were found in serum concentrations of tIS and PDE levels of IL-6 between the peritonitis and the peritonitis-free PD patients (Table 1). In addition, serum tIS was significantly associated with number of experienced peritonitis episodes (r = 0.26, P = 0.022). Although PDE levels of TNF-a and MCP-1 did not differ between the peritonitis and the peritonitis-free groups in our cohort, they had a direct association with serum tIS similar to those of IL-6 (Fig. 1, 2). Moreover, serum tIS was statistically higher in the anuric PD patients compared with the non-anuric patients [33.6 (13.9–74) versus 20.2 (9.3–46) μg/mL, P = 0.043], had a negative association with residual renal function (r = −0.39, P = 0.0017) and, accordingly, total weekly Kt/V (r = −0.27, P = 0.026). CONCLUSION Serum tIS concentration has a significant direct association with PDE levels of the pro-inflammatory markers, high peritonitis episodes and their outcomes in PD patients. Further well-designed studies are required to establish the effect of serum tIS concentration on intraperitoneal inflammation and clinical outcomes in PD patients.

MO692COULD THE RESIDUAL RENAL FUNCTION REMAIN A KEY DETERMINANT OF PLASMA OXALIC ACID CONCENTRATION IN PERITONEAL DIALYSIS PATIENTS?

Abstract Background and Aims Under physiological conditions, the bulk of circulating oxalate (90% to 95%) is ultimately excreted by the kidneys. Under uremic and/or anuric conditions, dialysis is considered to be the main method of oxalate removal. Nevertheless, little evidence is available on oxalate balance in peritoneal dialysis (PD) patients. The present study aimed to evaluate the separate contribution of residual renal and peritoneal oxalate clearances to oxalate balance in PD patients. Method We performed a cross-sectional observational study involving 62 PD patients with the average age of 50.5±13.5 years and PD vintage of 37±24 months. Plasma oxalate (POx) concentration, levels of daily urinary (UOx) and peritoneal dialysis effluent oxalate (PDEOx) excretion were evaluated. POx concentration was measured spectrophotometrically using MAK315 kit (Sigma, Spain); UOx and PDEOx concentrations were determined using an oxalate oxidase/peroxidase reagent (BioSystems, Spain). In addition, oxalate transport status (4-hour D/P oxalate ratio), renal oxalate clearance (ROxCL) and peritoneal oxalate clearance (PerOxCL) were calculated. Results Among the examined PD patients were 41 (66%) patients with preserved diuresis and 21 (34%) patients with anuria. The anuric PD patients had lower PerOxCL and, accordingly, peritoneal and overall oxalate removal levels compared with the patients with preserved diuresis (Table 1). Conclusion The results of our research demonstrated an important role of the residual renal function in oxalate balance in PD patients. However, the decline in RRF could partially (but not completely) contribute to the increase in POx in PD patients. Thus, PerOxCL but not ROxCL could significantly affect oxalate balance in PD patients.

Serum Concentration of Indoxyl Sulfate in Peritoneal Dialysis Patients and Low-Flux Hemodialysis Patients

Background/Aims: To compare the serum concentration of Indoxyl sulfate (IS) in patients on continuous ambulatory peritoneal dialysis (CAPD) and low-flux hemodialysis (HD), and analyze the risk factors associated with IS. Methods: We performed a single-center, cross-sectional observational study including 169 patients on CAPD and 115 patients on low-flux HD. Patients were divided into the anuric HD group, anuric peritoneal dialysis (PD) group, and non-anuric PD group on the basis of dialysis modality and residual urinary output. Serum concentration of IS was determined by high-performance liquid chromatography electrospray tandem mass spectrometry. Results: After matching the urinary volume and dialysis vintage, 58 anuric patients on PD and 58 anuric patients on HD were enrolled. The serum level of IS was significantly lower in patients on PD than that in those on HD (28.05 ± 13.98 vs. 39.64 ± 18.25 μg/mL; p < 0.001). This result persisted even after adjustment for confounding risk factors including nutritional status (β = 0.338, p < 0.001). In addition, the serum level of IS was significantly lower in non-anuric PD patients than that anuric PD patients (18.70 ± 11.21 vs. 28.05 ± 13.98 μg/mL; p < 0.001). After the adjustment for risk factors such as dialysis vintage, IS serum concentration in patients on PD was still significantly correlated with residual renal function (RRF; β = –0.355, p < 0.001). Conclusions: Dialysis modality is the independent risk factor of IS serum concentration and it is substantially lower in patients on CAPD than that in those on low-flux HD. Additionally, RRF was independently associated with IS serum concentration in CAPD patients, and the better the RRF is, the lower IS serum concentration.

Survival predictors in anuric patients on peritoneal dialysis: A prospective, multicenter, propensity score-matched cohort study.

Prevalent anuric peritoneal dialysis (PD) patients usually have higher mortality than PD patients with residual urine volume. We aimed to evaluate the predictors of survival in anuric PD patients. Anuric PD patients (n = 505, <100 mL of daily urine) enrolled in Korean nationwide prospective cohort were analyzed. Survived and non-survived anuric PD patients were compared by propensity score matching analysis with a ratio of two to one. The propensity method was used to adjust for patient age, dialysis duration, and presence of diabetes. Among the total anuric PD patients, non-survived patients showed a significantly older age, higher incidence of diabetes, coronary artery disease, and arrhythmia, and lower serum creatinine and albumin. After propensity score matching, multivariate Cox regression analysis for patient survival showed a decreasing risk as serum albumin increased (HR = 0.347, p = 0.0094). Analysis using the receiver-operating-characteristic (ROC) curve showed that survival could be predicted with a sensitivity of 59.4% and a specificity of 63.2% using a cutoff value of 3.6 g/dL of serum albumin in unmatched total PD patients. The beneficial impact of high albumin level on death was significantly greater for patients with older age (≥50 years), no diabetes, low ultrafiltration (UF) volume (<1000 mL/day), and low levels of serum creatinine (<10 mg/dL), total cholesterol (<177.5 mg/dL), ferritin (<100 ng/mL), and high-sensitivity C-reactive protein (hs-CRP) (<0.1 mg/dL). Survival in anuric PD patients was associated with age, comorbidities, and nutritional factors such as creatinine and albumin. After adjustment by propensity score matching, serum albumin level was an independent predictor for survival in anuric PD patients.

Does increased glucose exposure lead to increased body fat and reduced lean body mass in anuric peritoneal dialysis patients?

Residual renal function has been reported to be a major determinant of peritoneal dialysis (PD) technique survival for patients with end-stage kidney disease. Anuria leads to increases in PD prescriptions designed to maintain small solute clearances and ultrafiltration volumes, resulting in greater exposure to hypertonic glucose dialysates. We reviewed the effect of developing anuria in a cohort of 136 PD patients followed for a median of 12 months, to determine whether increasing exposure to higher glucose dialysates affected body composition by increasing body fat and reducing muscle mass. Despite increasing prescription of 22.7 and 38.6 g/l glucose dialysates there was no increase in body fat (31.1±15.4 vs 30.9±16.3 kg) or loss of fat-free weight (36.4±12.1 vs 35.8±12.3 kg). Changing PD prescriptions to maintain small solute clearances and ultrafiltration volumes did not lead to detrimental changes in body composition in the short term.

Dialysis adequacy in Chinese anuric peritoneal dialysis patients

We aimed in this study to explore how lower-protein diet would affect dialysis adequacy in anuric peritoneal dialysis (PD) patients. Patients' demographic features were collected, namely age, gender, weight, height, underlying renal disease, and time on PD. Urea kinetic model was used to assess solute clearance. A consecutive 3-day dietary record was collected to evaluate dietary protein intake (DPI), and normalized protein nitrogen appearance (nPNA) was also calculated to reflect protein intake. Blood samples were collected to measure hemoglobin and biochemistry. Patient's nutritional status was assessed by biochemistry, handgrip strength, and subjective global assessment (SGA). Body fluid distribution was measured by body composition monitor. Patients were 60.8 ± 14.92 years old, and the time on PD was 40.15 ± 22.90 months. Daily prescribed dialysis dose was 7,178 ± 1,326 mL. Kt/V was 1.6 ± 0.32. DPI was 0.8 ± 0.25 g/kg/day. nPNA was 0.9 ± 0.21 g/kg/day. Serum albumin was 39.42 ± 4.83 g/L. Prevalence of malnutrition (assessed by SGA) was 20.2 %. Serum phosphate and serum bicarbonate were 1.68 ± 0.47 and 27.16 ± 3.49 mmol/L, respectively. Systolic blood pressure and diastolic blood pressure were 123.4 ± 20.0 and 74.2 ± 12.6 mmHg, respectively. Patients with nPNA less than 0.6 had significantly lower serum albumin concentrations than the average, and patients with nPNA more than 1.2 g/kg/day had significantly higher levels of serum phosphate and serum urea than the average. Our study suggested that anuric PD patients could achieve adequate dialysis even under lower solute clearance. And lower-protein diet contributed largely to adequate dialysis in these patients.

Uremic Tumoral Calcinosis in Patients on Peritoneal Dialysis: Clinical, Radiologic, and Laboratory Features

Uremic tumoral calcinosis (UTC) has been analyzed in uremic patients on hemodialysis, but little is known about UTC in peritoneal dialysis (PD). In this study, we aimed to characterize UTC in uremic patients on PD. We retrospectively reviewed uremic patients on PD who developed UTC over a 9-year period. Clinical, radiologic, and laboratory features; treatments; and outcomes in those patients were assessed. One of the patients (case 7) is described as a case example. The study enrolled 7 patients with a mean age of 41 years. Mean time from PD to UTC was 45.3 months. All patients were anuric but adequately dialyzed. Cardinal symptoms were local tenderness and limited range of joint motion. Lesions were mostly multifocal (n=6) and predominantly involved shoulders, hands, feet, hips, and wrists. Metatarsophalangeal joint UTC was misdiagnosed as tophaceous gout in 2 patients. Main laboratory findings were hyperphosphatemia (7.9 ± 0.8 mg/dL), high Ca×P product [>65 mg(2)/dL(2) (range: 81.1 ± 11.5 mg(2)/dL(2))], secondary hyperparathyroidism (SHPT) with various levels of intact parathyroid hormone (iPTH: 592.2 ± 315.2 pg/mL; <250 pg/mL in 2 patients). Medical treatments for UTC included P restriction, non-Ca-based phosphate binders, and adequate dialysis with low-Ca dialysate, but all treatments were ineffective. Parathyroidectomy (n=3) can partially ameliorate UTC, but only 1 patient (case 7), who had extremely high iPTH (1085 pg/mL), manifested hungry bone syndrome (HBS) and had remarkable resolution of UTC. By contrast, in patients who underwent renal transplantation (n=3), UTC completely resolved by about 1 year after surgery. Uremic tumoral calcinosis develops in anuric PD patients with uncontrolled hyperphosphatemia; it is usually multifocal, occurring around the weight-bearing joints or overused smaller joints. Aggressive medical therapy alone is ineffective, and parathyroidectomy appears to be unsatisfactory except in the presence of severe SHPT with postoperative HBS.

Daily peritoneal ultrafiltration predicts patient and technique survival in anuric peritoneal dialysis patients

Maintenance dialysis therapy is the only way to remove excess fluid in patients with anuric end-stage renal disease. The optimal ultrafiltration (UF) volume in patients on peritoneal dialysis (PD) remains controversial. We retrospectively analysed a cohort of 86 prevalent anuric PD patients followed up for a median of 25.3 months (range, 6 to 54 months). Clinical and PD parameters were recorded yearly. Kaplan-Meier analysis and Cox proportional hazards models were used to identify risk factors of mortality and technique failure in patients with a UF >/=1 L/24 h or <1 L/24 h. When compared to those with a UF <1 L/24 h, patients with a UF >/=1 L/24 h had significantly higher haemoglobin levels (101.9 +/- 20.5 vs 89.3 +/- 20.2 g/L, P < 0.05) and tended to be younger (55.0 +/- 12.5 vs 60.6 +/- 16.1 years, P = 0.10). Also, while Kt/V and CCr were stable over time, UF decreased significantly over the study period (baseline, 1205.5 +/- 327.3 ml/24 h vs after 3 years, 870.6 +/- 439.8 ml/24 h; P < 0.001). Using Kaplan-Meier analysis, patients with baseline UF <1 L/24 h had significantly worse outcome (survival, 27.2 +/- 3.9 vs 42.4 +/- 1.9 months; P < 0.001). In multivariate Cox regression analysis, age, time-dependent UF volume and serum albumin were independent predictors of mortality, while UF independently predicted technique failure. The present study demonstrates a strong predictive value of daily peritoneal UF for both technique and patient survival in prevalent anuric PD patients. Identifying markers of satisfactory fluid status, as well as optimizing therapy to meet UF goals, remains an important clinical target.

Diagnostic potential of serum biomarkers for left ventricular abnormalities in chronic peritoneal dialysis patients

N-terminal-pro-brain natriuretic peptide, cardiac troponin T (cTnT) and high sensitivity C-reactive protein (hs-CRP) have been shown to predict mortality and cardiovascular outcomes in end-stage renal disease patients. However, it is not known which biomarkers have the strongest diagnostic potential for left ventricular (LV) abnormalities in chronic peritoneal dialysis (PD) patients, nor whether residual renal function may confound the diagnostic potential of these biomarkers. Two hundred and thirty chronic PD patients underwent two-dimensional echocardiography to determine LV hypertrophy and ejection fraction and had simultaneous measurement of serum NT-pro-BNP, cTnT and hs-CRP. A significant gain in predictive power was observed when NT-pro-BNP or cTnT but not hs-CRP was included in the multivariable logistic regression models for severe LV hypertrophy (defined as LV mass index > or = upper tertile, 247.8 g/m(2)) and systolic dysfunction (defined as ejection fraction < or =45%). Using ROC curve analysis, NT-pro-BNP had the highest diagnostic value for severe LV hypertrophy and systolic dysfunction compared to cTnT and hs-CRP, irrespective of residual renal function. An analysis based on the best cut-off threshold showed that NT-pro-BNP and cTnT had a negative predictive value of 87.1% and 92.6% for severe LV hypertrophy and 95.4% and 93.2% for systolic dysfunction, respectively. Furthermore, the best cut-off threshold of NT-pro-BNP and cTnT for excluding severe LV hypertrophy and systolic dysfunction was nearly 3-fold higher in anuric patients than in patients with residual renal function. Serum NT-pro-BNP appeared most useful in excluding systolic dysfunction in chronic PD patients followed by cTnT. hs-CRP was not useful in this regard. Residual renal function confounded the interpretation of these biomarkers and reduced their predictive power. A nearly 30% higher cut-off threshold of NT-pro-BNP and cTnT had to be applied in anuric PD patients.

Association of Kt/V and Creatinine Clearance With Outcomes in Anuric Peritoneal Dialysis Patients

The 2006 Kidney Disease Outcomes Quality Initiative recommended a minimum total Kt/V of 1.7, eliminated creatinine clearance (Ccr) as a target, and recommended the use of ideal body weight to calculate Kt/V. We assessed these recommendations as predictors of outcomes in anuric peritoneal dialysis patients. Retrospective observational study using administrative data. 1,432 peritoneal dialysis patients with anuria from January 1, 1994, to January 31, 2005, in a national sample (1,428 with Kt/V, 1,416 with Ccr). Kt/V and Ccr at anuria; Kt/V based on actual body weight and ideal body weight. Association of dialysis adequacy with mortality and time to first hospitalization after anuria assessed by using accelerated failure time models. 293 anuric patients had Kt/V less than 1.7, 366 had Kt/V of 1.7 to 2.0, and 769 had Kt/V greater than 2.0, using actual body weight for calculation. In unadjusted analyses, Kt/V calculated using actual body weight both less than 1.7 (-41.3%; 95% confidence interval [CI], -55.5 to -22.6) and 1.7 to 2.0 (-26.1%; 95% CI, -42.6 to -4.6) were associated with shorter time to mortality. Kt/V calculated using actual body weight less than 1.7 was associated with shorter time to hospitalization (-38.1%; 95% CI, -50.0 to -23.4), but Kt/V calculated using actual body weight of 1.7 to 2.0 was not a significant predictor (-3.3%; 95% CI, -21.1 to 18.6). After adjustment, Kt/V calculated using actual body weight less than 1.7 remained associated with mortality (-25.3%; 95% CI, -41.1 to -4.8) and hospitalization (-33.4%; 95% CI, -47.1 to -16.0). Ccr did not predict mortality. In unadjusted analysis, Ccr was not associated with hospitalization, but after adjustment, Ccr less than 50 L/wk/1.73 m(2) was significantly associated with shorter time to hospitalization (-19.9%; 95% CI, -35.0 to -1.3). Kt/V using ideal body weight was not a significant predictor in adjusted models. This study was nonrandomized, with few malnourished patients. In addition, there is a potential for informative censoring for transfer to hemodialysis therapy before anuria. Kt/V calculated using actual body weight less than 1.7 in anuric peritoneal dialysis patients is associated with increased mortality and hospitalization. Use of ideal body weight to calculate Kt/V weakened the associations with outcomes and therefore cannot be recommended.

Combination of Crystalloid (Glucose) and Colloid (Icodextrin) Osmotic Agents Markedly Enhances Peritoneal Fluid and Solute Transport during the Long PD Dwell

Fluid and sodium removal is often inadequate in peritoneal dialysis patients with high peritoneal solute transport rate, especially when residual renal function is declining. We studied the effects of using simultaneous crystalloid (glucose) and colloid (icodextrin) osmotic agents on the peritoneal transport of fluid, sodium, and other solutes during 15-hour single-dwell exchanges using 3.86% glucose, 7.5% icodextrin, and a combination fluid with 2.61% glucose and 6.8% icodextrin in 7 prevalent peritoneal dialysis patients with fast peritoneal solute transport rate. The combination fluid enhanced net ultrafiltration (mean 990 mL) and sodium removal (mean 158 mmol) compared with 7.5% icodextrin (mean net ultrafiltration 462 mL, mean net sodium removal 49 mmol). In contrast, the 3.86% glucose-based solution yielded negligible ultrafiltration (mean -85 mL) and sodium removal (mean 16 mmol). The combination solution resulted in significantly improved urea (+41%) and creatinine (+26%) clearances compared with 7.5% icodextrin. A solution containing both crystalloid (glucose 2.61%) and colloid (icodextrin 6.8%) osmotic agents enhanced fluid removal by twofold and sodium removal by threefold compared with 7.5% icodextrin solution during a dwell of 15 hours, indicating that such a combination solution could represent a new treatment option for anuric peritoneal dialysis patients with high peritoneal solute transport rate.

Predictors of survival in anuric peritoneal dialysis patients

Residual glomerular filtration rate (GFR) is a much more important determinant of survival in peritoneal dialysis patients, than peritoneal solute clearances. However, anuric peritoneal dialysis patients are solely dependent on peritoneal solute clearances. The aim of the study was to analyze the effects of peritoneal small solute clearances and ultrafiltration on survival in anuric patients, and to establish the minimum levels of small solute clearances and net ultrafiltration. These objectives were investigated in a prospective cohort study in incident peritoneal dialysis patients who had become anuric during follow-up. The Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD) is a prospective multicenter cohort study in which new adult dialysis patients are included and followed during 6 months intervals. Included were 542 peritoneal dialysis patients. Of these, 166 developed anuria, 130 of which could be included in the study. Two-year patient survival after the outset of anuria was 67%, technique survival 73%, and the combined 2-year patient and technique survival was 50%. Risk factors associated with mortality were age, comorbidity, the duration of peritoneal dialysis before anuria, and a low serum albumin. Peritoneal solute clearances were analyzed time-dependently. These parameters were not associated with survival when analyzed as continuous variables and also not when the analyses were done in quintiles, although the time-dependent approach was almost significant for Kt/V(urea). On the other hand, when the results were analyzed dichotomously using predefined cutoff points, Kt/V(urea) <1.5 per week and creatinine clearance <40 L/week/1.73 m2 were associated with an increase in the relative risk of death. Also peritoneal ultrafiltration was significantly associated with survival. The survival of anuric peritoneal dialysis patients is in line with expectations based on the duration of dialysis. The risk factors for death are the same as in the dialysis population as a whole. Besides an association with ultrafiltration, our study enabled us to define the lower limits of adequate peritoneal dialysis, that is Kt/V(urea) <1.5 per week and creatinine clearance <40 L/week/1.73 m2.

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

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

High Peritoneal Clearance of Small Molecules Did Not Provide Low Serum β2–Microglobulin Concentrations in Peritoneal Dialysis Patients

Although early reports demonstrated that serum beta(2)-microglobulin (s-beta(2)m) concentrations in patients on peritoneal dialysis (PD) were lower than those in patients on hemodialysis (HD), more recent studies demonstrated lower s-beta(2)m concentrations in HD patients treated mainly with high-flux synthetic membranes. We therefore compared s-beta(2)m concentrations between patients on PD and on HD, and also analyzed the relationship between s-beta(2)m concentrations and other parameters in patients on PD. We investigated 24 patients who had been undergoing PD [11 on continuous ambulatory peritoneal dialysis, 13 on continuous cycling peritoneal dialysis] for 4.3 +/- 2.7 years, and 24 patients who had been undergoing HD with high-flux synthetic membranes for 6.1 +/- 3.2 years. Concentrations of s-beta(2)m in the PD patients were compared to concentrations in the HD patients. In patients on PD, we also analyzed the relationship between s-beta(2)m concentration and other parameters, including residual renal function, total weekly Kt/V urea, total weekly creatinine clearance (CCr), and dialysis schedules. We found no significant difference in s-beta(2)m concentrations between the PD and HD patients (33.6 +/- 10.4 mg/L vs 30.3 +/- 10.5 mg/L respectively). Concentrations of s-beta(2)m in PD patients rose with PD duration and were significantly inversely correlated with residual renal function (r = -0.71, p < 0.0001). Unexpectedly, concentrations of s-beta(2)m in anuric PD patients rose as peritoneal CCr increased. And most of the patients with high s-beta(2)m levels fell into the high or high-average transport categories according to a peritoneal equilibration test. Concentrations of s-beta(2)m in patients on PD did not differ significantly from concentrations in HD patients who were using high-flux synthetic membranes. The contribution of residual renal function to removal of beta(2)m was more important than the contribution of peritoneal clearance. High peritoneal clearance of small molecules did not result in low s-beta(2)m concentrations, especially in anuric patients with accelerated peritoneal permeability.

The Relationship between Kt/VUrea and Npna in Anuric Peritoneal Dialysis Patients: A Comparison with Predialysis Patients

It is unknown whether a given level of urea clearance by the native kidneys provides better or similar control of uremia than the same level of urea clearance by continuous peritoneal dialysis (PD). More insight into possible differences between renal and peritoneal urea clearances is warranted. Therefore, we investigated the relationship between Kt/V(urea) and protein equivalent of total nitrogen appearance normalized to body weight (nPNA), the relationship between urea clearance and creatinine appearance, and other nutritional parameters in PD patients without residual renal function, and in predialysis end-stage renal disease patients. All patients participated in the Netherlands Cooperative Study on the Adequacy of Dialysis. This is a prospective cohort study of incident dialysis patients, in whom regular assessments of renal function are done. A group of 75 PD patients was identified at the first follow-up assessment in which their urine production was less than 100 mL/day. These patients were considered the anuric group. This group was compared with a control group of 97 predialysis patients studied 0-4 weeks before the start of dialysis treatment. Linear relationships were present between Kt/V(urea) and nPNA, in both the predialysis patients and the anuric PD patients. A significant difference was present between the slopes of the two regression lines (0.40 vs 0.18, p = 0.007). When Kt/V(urea) exceeded 1.3/week, a given level of Kt/V(urea) was associated with a higher nPNA in predialysis than in anuric PD patients. Similar relationships were found between Kt(urea) and PNA. Kt(urea) was also significantly related to urine or dialysate creatinine appearance. A significant difference existed between the slopes of the regression lines in the two groups of patients (p < 0.001). A weekly Kt(urea) of 70 L was associated with a urine creatinine appearance of 11.0 mmol/day and a dialysate creatinine appearance of 8.4 mmol/day. Nutritional status measured with creatinine appearance and Subjective Global Assessment was better in the predialysis population, despite much lower values for Kt/V(urea) in these patients. The relationship between Kt/V(urea) and nPNA in anuric PD patients is different from that in a predialysis population. It follows from our results that, when Kt/V(urea) is above 1.3/week, a given level of Kt/V(urea) is associated with a higher nPNA in predialysis than in anuric PD patients. This challenges the concept of equivalency between renal and peritoneal Kt/V(urea) with respect to control of uremic morbidity.

The Effect of Small Solute Clearances on Survival of Anuric Peritoneal Dialysis Patients

Primarily, to determine whether peritoneal small solute clearance is related to patient and technique survival among anuric peritoneal dialysis [continuous ambulatory (CAPD) and automated peritoneal dialysis (APD)] patients. A secondary goal was to describe the ability to attain Dialysis Outcomes Quality Initiative (DOQI) targets among anuric patients on peritoneal dialysis. Retrospective cohort study via chart reviews. Peritoneal Dialysis Unit of Toronto Hospital (Western Division). The study included 122 CAPD and APD patients between January 1992 and September 1997, with 24-hour urine volume less than 100 mL, or renal creatinine clearance (CCr) less than 1 mL/minute. Adequacy data were available for 115 patients. Mortality and technique failure (TF). Regression analysis was used to estimate the mortality and TF rate ratios (RR) for peritoneal Kt/V urea (pKt/V) and pCCr, adjusting for age, gender, diabetes, months of follow-up prior to anuria, albumin, transport status, coronary artery disease, cardiovascular disease, and peripheral vascular disease. Fifty seven per cent (51/89) of patients on CAPD and 81% (21/26) on APD had a weekly pKt/V > or = 2 and > or = 2.2, respectively (DOQI targets); whereas only 35% on CAPD (31/89) and 35% (9/26) on APD had a weekly pCCr > or = 60 U1.73 m2 and 66 L/1.73 m2, respectively. Median follow-up times among patients were 16.5 and 19.5 months pre- and postanuria, respectively. Patients with pKt/V > or = 1.85 experienced a strong decrease in patient mortality (RR = 0.54, p= 0.10); the effect was less pronounced for pCCr > or = 50 L/1.73 m2 (RR = 0.63, p = 0.25). No relationship was observed between pKt/V or pCCr and TF. Mortality was noticeably less frequent among patients with a pKt/V > or = 1.85 compared with those with a Kt/W < 1.85 (p = 0.10). Given the magnitude of the association, the failure to observe statistical significance relates to the size of the patient cohort. Our results imply that it is, in fact, possible to achieve DOQI targets among anuric patients on peritoneal dialysis.

Drain Volume Required for a Target Peritoneal Clearance

The authors developed formulae calculating the daily drain volume (DV) required for a target normalized peritoneal clearance of urea (Kt/V(ur)) or creatinine (Ccr, Kt/Vcr) in peritoneal dialysis (PD). DV depends on the target clearance, the peritoneal solute transport type, and the size of the person as expressed by body surface area (BSA) or body water (V). To illustrate the formulae, we constructed nomograms for the following weekly target clearances: Ccr = 60 L/1.73 m2, Kt/V(ur) = 2.0, Kt/Vcr = 1.8 (the value corresponding to a Ccr of 60 L/1.73 m2 in a linear regression of the two parameters in 476 clearance studies in continuous ambulatory PD [CAPD] patients). The PD schedules studied included CAPD, continuous cycling PD (CCPD) with one 2 L daytime dwell, and a combination of daytime CAPD and nighttime automated PD (APD) with 2 hr dwell times. Peritoneal transport was characterized as low, low-average, high-average, or high by the dialysate-to-plasma (D/P) creatinine concentration ratio in a peritoneal equilibration test (PET). The D/P value entered for each transport type was the appropriate 95% lower confidence limit of the mean D/P in actual studies (2 hr and 4 hr D/P from 102 PET studies and 5.5 hr D/P from 476 clearance studies in CAPD patients). For high transport, the required DV values were similar in all three PD schedules studied. For low transport, the required DV was much larger, comparatively, for CCPD and CAPD-APD than for CAPD. Furthermore, the DV values required for a weekly Kt/V(ur) of 2.0 were comparatively less than the DV values required for a weekly Kt/Vcr of 1.8 (Ccr of 60 L/1.73 M2). Calculation of the DV required for different PD schedules, a target peritoneal clearance, and the patients's size is feasible when the patient's peritoneal transport characteristics are known. This calculation also allows the selection of the least costly PD schedule. Current target values for urea and creatinine clearance are incompatible in anuric PD patients.