Heterogeneity in peritoneal transport during continuous ambulatory peritoneal dialysis and its impact on ultrafiltration, loss of macromolecules and plasma level of proteins, lipids and lipoproteins

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.

Ysis Prescription and Peritoneal Membrane Transport Characteristics on Nutritional Status

These data suggest that dialysis dose is one of the major determinants of protein and energy intake in PD patients and that higher doses of dialysis tend to improve outcome. The data also suggest that with a long time on PD the peritoneal membrane probably has some underlying histological changes that preclude it from optimally responding to injury and may predispose it to irreversible damage. A possible early finding in this case is an increase in peritoneal transport in patients whose transport was initially stable. Peritoneal membrane transport properties are an important determinant of not only dialysis dose, but also nutritional status via both direct and indirect means. It is therefore important to identify the individual patient's peritoneal membrane transport characteristics. These transport characteristics may change over time. High transporters on CAPD represent a unique challenge. They have ultrafiltration problems and a tendency toward protein malnutrition presumably due to increased dialysate protein losses while on CAPD. One must consider that malnutrition in a rapid transporter may be due to the fact that the patient is on the wrong PD therapy. A change to NIPD may rectify some of the biochemical parameters, but these patients may not always improve. Reasons for this occasional lack of improvement are multifactorial, but emphasize our need to look at each patient as an individual and not focus only on laboratory parameters.

Residual Renal Function Affects Lipid Profile in Patients Undergoing Continuous Ambulatory Peritoneal Dialysis

Objective

To determine whether lipoprotein abnormalities associated with continuous ambulatory peritoneal dialysis (CAPD) are influenced by residual renal function (RRF).

Design

Open, non randomized prospective and com -parative study.

Setting

Single university teaching hospital dialysis unit and outpatient clinic.

Patients

Twenty adult patients on standard CAPD (1 -38 months) were divided into two groups: group A (RRF ≤ 0.8 mL/min, n = 10) and group B (RRF ≥ 1.1 mL/ min, n = 10). Patients in the two groups were matched for age, time on dialysis, body weight, body mass index, serum urea and albumin levels, peritoneal and urinary albumin losses, and peritoneal transport characteristics such as overnight 8hour peritoneal creatinine and β2-microglobulin clearances and overnight 8-hour effluent glucose concentrations.

Results

The degree of uremia in patients with preserved RRF (group B) was obviously lower than in patients with negligible RRF (group A), that is, patients in group B had significantly lower serum creatinine and β2-microglobulin levels and significantly higher weekly KTN than group A patients. Despite the prevalence of allele 4 of apolipoprotein E genotype in group A patients, their levels of serum total cholesterol, low-density lipoprotein cholesterol, lipoprotein (a) [Lp(a)], apolipoprotein B (ApoB), and apolipoprotein A1 (ApoA1) were significantly lower than those of patients with preserved RRF (group B). The two groups did not differ significantly in the serum levels of triglyceride or high-density lipoprotein cholesterol. Serum concentrations of Lp(a) and ApoA1, as well as ratios of ApoA1 to ApoB, were correlated significantly with RRF (r = 0.63, r = 0.51, and r = 0.61, respectively).

Conclusions

The findings suggest that RRF affects the lipid profile of CAPD patients, especially serum levels of cholesterol-rich lipoproteins.

Complement in Serum and Dialysate in Children on Continuous Ambulatory Peritoneal Dialysis

Objective

During continuous ambulatory peritoneal dialysis (CAPD), activation of complement in the peritoneal cavity may theoretically occur, with inappropriately high or low levels of certain complement factors in dialysate as a consequence. In a group of children on CAPD, it was tested whether levels of a number of complement factors in dialysate were in the range that was predicted on the basis of their molecular weight.

Design

Serum and dialysate levels of C1 q, C3, C4, C3d, B, D, and P were measured after a night dwell in children on CAPD. Simultaneously, four non-complement proteins (β2-microglobulin, albumin, IgG, and α2macroglobulin) were also measured in dialysate and serum. Assuming a linear relationship between the log base 10 of the dialysate/serum ratio of these non-complement proteins and the log base 10 of their molecular weight, the expected ratios of all complement factors were determined. The differences between actual and predicted ratios were tested using a modified t-test, taking into account the inaccuracy of the estimate.

Setting

University hospital.

Patients

A group of 14 children on CAPD, with a median age of 7.8 years (range 2.1–13.2). These children had been on CAPD for a median period of 42.4 months (range 0.4 89.1).

Results

The ratios of factor D (p < 0.001) and C3d (p = 0.035) were elevated, whereas those of C3 (p < 0.001), C4 (p < 0.001), and factor P (p = 0.012) were decreased.

Conclusions

Relatively low dialysate/serum ratios of C4, C3, and factor P could be caused by intraperitoneal consumption of complement. High levels of C3d are compatible with this. High dialysate/serum ratios of factor D indicate intraperitoneal production of factor D. These results provide evidence for activation of complement in the peritoneal cavity in children on CAPD. A further reduction of already low levels of complement factors in dialysate as a result of this may impair host defense.

Effect of Dialysis Modality and Membrane Transport Characteristics on Dialysate Protein Losses of Patients on Peritoneal Dialysis

Objective

To determine if peritoneal dialysis modality has an impact on protein losses in dialysate.

Design

Retrospective, cross-sectional study.

Patients

190 patients who had selected peritoneal dialysis were classified into one of four transport categories (high, high-average, low-average, or low) based on standard peritoneal equilibration test results. Patients were then assigned to continuous ambulatory peritoneal dialysis (CAPD) or nightly intermittent peritoneal dialysis (NIPD) based on membrane transport characteristics and individual preferences.

Results

Patients with similar membrane transport characteristics had essentially no differences in dialysate protein and albumin losses whether treated with CAPD or NIPD.

Conclusions

Although high transporters may be better managed with short -dwell therapies such as nocturnal intermittent peritoneal dialysis or daily ambulatory peritoneal dialysis, consistent marked decreases in protein losses cannot be cited as a benefit of NIPD over CAPD.

Relationships between Peritoneal Protein Clearance and Parameters of Fluid Status Agree with Clinical Observations in other Diseases that Venous Congestion Increases Microvascular Protein Escape

Background

Peritoneal effluent from peritoneal dialysis (PD) patients contains proteins, mainly transported from the circulation through large pores in the venular part of the peritoneal micro-vessels. Hydrostatic convection is the major driver for peritoneal protein transport, although in PD there is additional diffusion. Consequently, venous pressure may have a role in peritoneal protein transport. The aim of the study was to investigate the importance of venous congestion on the magnitude of peritoneal protein clearance in incident PD patients using non-invasive measurements.

Methods

A total of 316 adult PD patients, on PD for 8 - 12 weeks and collecting 24-hour urine and dialysate for total protein determination, underwent standard peritoneal equilibration testing (PET) along with measurement of N terminal pro-brain natriuretic peptide (NT-proBNP) and C-reactive protein (CRP), multifrequency bioimpedance analysis, and a transthoracic echocardiogram.

Results

Statistically significant univariate relationships for peritoneal protein clearance with a Spearman correlation coefficient > 0.25 were present for 4-hour dialysate/plasma (D/P) creatinine, NT-proBNP, extracellular/total body water, extracellular water excess, left ventricular mass, and right atrial area. Negative correlations were found with serum total protein and residual renal function. On multivariate analysis, logNTproBNP (β 0.11, p = 0.007) and right atrial area (β 0.01, p = 0.03) were significant independent predictors of peritoneal protein clearance.

Conclusion

Indicators of venous congestion showed the most important relationships with peritoneal protein clearance. These indicators have not been assessed in previous studies on the presence or absence of relationships between peritoneal protein clearance and mortality.

Dyslipidemia associated with chronic kidney disease

Cardiovascular disease is a major cause of morbidity and mortality in patients with impaired renal function. Dyslipidemia has been established as a well-known traditional risk factor for cardiovascular disease (CVD) in the general population and it is well known that patients with chronic kidney disease (CKD) exhibit significant alterations in lipoprotein metabolism. In this review, the pathogenesis and treatment of CKD-induced dyslipidemia are discussed. Studies on lipid abnormalities in predialysis, hemodialysis and peritoneal dialysis patients are analyzed. In addition, the results of the studies that tested the effects of the hypolipidemic drugs on cardiovascular morbidity and mortality in patients with CKD are reported.

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.

Peritoneal Transport Status Influence on Atherosclerosis/Inflammation in CAPD Patients

OBJECTIVE

Peritoneal transport status is one of the main determinants of dialysis adequacy and dialysis-related complications in end-stage renal disease patients receiving continuous ambulatory peritoneal dialysis (CAPD). In this study we aimed to investigate the relationship between peritoneal transport characteristics and known promoters of atherosclerosis in a group of patients receiving CAPD for a minimum of 36 months.

DESIGN AND PARTICIPANTS

We performed a cross-sectional study of a cohort of 84 patients with end-stage renal disease (37 men, 47 women; age, 44.0 +/- 15.7 years; dialysis duration, 40.3 +/- 8.1 months) who were receiving CAPD for minimum 36 months. Peritoneal transport characteristics were identified after a peritoneal equilibration test (PET) determined at the third month of CAPD using Dialysate/Plasma (D/P) reference values. Patients were classified according to one of four peritoneal transport types: high (H), high-average (HA), low-average (LA), and low (L). After PET, patients were grouped as high (H/HA group, n = 51) or low (L/LA group, n = 33) transporters. The patient groups' clinical and laboratory data before dialysis and after initiation of the CAPD were collected retrospectively. The patients' follow-up data were retrieved for the diagnosis of any atherosclerosis-related event after the initiation of CAPD. The following events were collected, including myocardial infarction, having been diagnosed as having coronary artery disease by angiography or myocardium scintigraphy, cerebrovascular accident, and development of clinically evident peripheral arterial disease.

RESULTS

A comparison of follow-up data revealed that the H/HA transport characteristic was associated with lower albumin (P < .01), higher C-reactive protein (CRP) (P < .0001) levels, and higher recombinant human erythropoietin (rHuEPO) needs (P < .001) when compared with the L/LA type. During follow-up, 28 patients showed an atherosclerosis-related event. Twenty-two of these were in the H/HA group (43.1%), whereas only six were in the L/LA group (18.1%, P < .01). Reanalysis of 18 patients with atherosclerosis-related events and high CRP levels (> 10 mg/L) showed that 15 were in the H/HA and 3 were in the L/LA group. Sixty-eight percent of the H/HA patients with atherosclerosis and 50% of the L/LA patients with an atherosclerotic event also had chronic inflammation (P < .001). A Pearson correlation analysis showed that there was a positive correlation between D/P creatinine levels and 36-month mean CRP levels (r = 0.608, P < .0001), and a negative correlation between D/P creatinine levels and 36-month mean albumin levels (r = -0.299, P < .005).

CONCLUSIONS

This study shows that the high transporter peritoneal membrane characteristic is a risk factor for inflammatory state in patients with end-stage renal disease. High-transporter patients are at an increased risk of atherosclerosis when compared with their low-transporter counterparts through chronic inflammation.

Hypoproteinemia in Patients with Diabetes Undergoing Continuous Ambulatory Peritoneal Dialysis is Attributable to High Permeability of Peritoneal Membrane

Background

The present study used the newly developed personal dialysis capacity (PDC) peritoneal function test to investigate differences in individual peritoneal membrane transport function and nutritional status in non diabetic (non DM) and diabetic (DM) patients on continuous ambulatory peritoneal dialysis (CAPD).

Patients and Methods

To clarify the differences in peritoneal function that determine plasma protein levels, we carried out PDC tests in non DM and DM patients. Between May 1995 and May 1999, in multicenter study in Japan, we carried out 232 PDC tests on 232 non DM patients and 47 PDC tests on 47 DM patients who had been on CAPD for 1 – 210 months.

Results

Plasma levels of total protein and albumin in DM patients were significantly lower than those in non DM patients (total protein: 6.5 ± 0.1 g/dL non DM vs. 5.9 ± 0.1 g/dL DM, p < 0.0001; albumin: 3.5 ± 0.1 g/dL non DM vs. 2.9 ± 0.1 g/dL DM, p < 0.0001). The mean membrane area in the DM group was significantly larger than that in the non DM group (21943 ± 608 cm/1.73 m2non DM vs. 26 304 ± 1699 cm/1.73 m2DM, p = 0.0076). The mean plasma loss through the large pores in the DM group was significantly greater than that in the non DM group (0.095 ± 0.004 mL/min/1.73 m2non DM vs. 0.119 ± 0.008 mL/min/1.73 m2DM, p = 0.0113). Protein loss into dialysate in DM patients was significantly greater than that in non DM patients. We observed a significant correlation between total protein or albumin and plasma loss from dialysis solution in non DM and DM patients on CAPD.

Conclusions

The study demonstrated that peritoneal function, including peritoneal membrane transport and peritoneal permeability to protein was significantly higher in DM patients than in non DM patients. Hypoproteinemia in DM patients might be associated with high permeability of peritoneal membrane in CAPD.

Effect of diabetes on peritoneal function assessed by personal dialysis capacity test in patients undergoing CAPD

BACKGROUND

We evaluated differences in individual peritoneal membrane transport function and nutritional status in patients with diabetes mellitus (DM) and nondiabetic (non-DM) patients on continuous ambulatory peritoneal dialysis (CAPD).

METHODS

We used a newly developed peritoneal function test, personal dialysis capacity, in 88 patients (44 DM and 44 non-DM) on CAPD for 1 to 210 months. Sex, age, past history of peritonitis, and duration of CAPD were matched in DM and non-DM patients.

RESULTS

Serum albumin (mean +/- SEM) was lower in DM compared with non-DM patients: 3.0 +/- 0.1 g/dL (30 +/- 1 g/L) versus 3.5 +/- 0.1 g/dL (35 +/- 1 g/L), P < 0.001. Peritoneal area and dialysis protein loss were greater in DM versus non-DM patients. In multiple linear regression analysis, the only independent predictor of serum albumin in patients with DM was dialysis protein loss. In contrast, age, past history of peritonitis, duration of CAPD, caloric intake, protein nitrogen appearance and protein catabolic rate, and residual renal function did not correlate with serum albumin in DM patients. In non-DM patients, age, duration of CAPD, and past history of peritonitis, but not dialysis protein loss, were independent predictors of serum albumin. There was a significant correlation in DM patients, but not in non-DM CAPD patients, between dialysis protein loss and urinary excretion of protein (r = 0.866, P = 0.0005).

CONCLUSION

In this multicenter study, peritoneal membrane transport and peritoneal protein permeability were significantly higher in DM than in non-DM patients. Hypoproteinemia in DM patients is attributable to the high permeability of the peritoneal membrane undergoing CAPD.

Peritoneal protein loss in patients with high peritoneal permeability: comparison between continuous ambulatory peritoneal dialysis and daytime intermittent peritoneal dialysis

BACKGROUND

Dialysate protein loss is involved in the etiology of hypoalbuminemia and malnutrition on continuous ambulatory peritoneal dialysis (CAPD). Patients with high peritoneal membrane permeability had the lowest serum albumin (Alb) and highest dialysate protein concentrations and achieved higher small solute dialysis/plasma equilibration in a shorter time than patients with low peritoneal transport. The aim of this prospective crossover study was to evaluate whether protein loss might be decreased in patients with high peritoneal permeability on short dwell-time (DT) peritoneal dialysis.

METHODS

Five high and nine high-average peritoneal transport patients were subjected to the following sequential dialysis schemes (four exchanges/day, glucose 1.5%): scheme A, three daytime exchanges (4-6 h DT) and one nightly (8-12 h DT) for 2-3 days, scheme B, 3-h DT each and dry peritoneum at night during 5 days, a wash-out period similar to scheme A, and scheme C, 2-h DT each and dry peritoneum the remainder of day and night during 5 days. Dialysate Alb, IgG, IgA, and IgM losses and adequacy of dialysis were evaluated at the end of each scheme.

RESULTS

Dialysate IgM was not detected. All protein losses were reduced with the short DT dialysis schemes; however, dialysis CCl and KT/V(urea) were also decreased. In patients with high peritoneal transport type, the 3-h DT dialysis scheme achieved a reduction in Alb loss without significant reduction of adequacy of dialysis.

CONCLUSIONS

Peritoneal Alb, IgG, and IgA losses are significantly reduced in patients with high peritoneal permeability on short dwell-time dialysis and extended dry periods. However, a reduction of dialysis contribution to small solute clearances was also observed, Three-hour dwell-time dialysis may be particularly useful in patients with high peritoneal transport type, as it tends to reduce peritoneal protein loss without notably reducing adequacy of dialysis.

Adequacy of peritoneal dialysis

The National Kidney Foundation-Dialysis Outcomes Quality Initiatives guidelines have standardized many aspects of treating end-stage renal disease patients with peritoneal dialysis in an attempt to improve overall patient outcome. While recommending certain total solute clearance goals, the guidelines have also pointed out deficiencies in our knowledge base and precipitated many controversies. Some of these controversies have been resolved while others may have been interpreted wrongly, unnecessarily resulting in transfer of patients from peritoneal dialysis to hemodialysis due to "failure to meet adequacy targets" even when doing well clinically. This report reviews the rationale for the original guidelines and their subsequent modification. It also outlines a rational approach toward prescription modification based on peritoneal physiology. Specific solute clearance target goals discussed are the modifications for continuous ambulatory peritoneal dialysis (CAPD) and cycler peritoneal dialysis (CCPD), and a review of what solute clearance targets subsequent guidelines from other countries have used. Some examples are as follows: new guidelines suggest that solute clearance goals for creatine clearance should differ for low and low-average transporters than for high and high-average transporters (weekly clearance of 50 and 60 1/1.73 m(2), respectively) while Kt/V targets remain unchanged. Also discussed is the rationale for having the same target for patients on CCPD with a mid-day exchange as those for patients on CAPD. We are also reminded that solute clearance is only one aspect of "adequate" dialysis-blood pressure and volume control are equally important, and ways to maintain euvolemia and blood pressure control are discussed in the context of prescription management.

Pathogenic effects of a high peritoneal transport rate

Recent studies have shown that patients with high peritoneal transport characteristics have substantially increased morbidity and mortality. This finding is counter-intuitive, since HTs will a priori achieve higher clearances. There are many possible causes: increased protein losses with consequent hypoalbuminemia; poor ultrafiltration capacity causing fluid retention, ventricular hypertrophy and hypertension; increased glucose absorption leading to anorexia, hyperinsulinism, and local AGE formation; and the development of an atherogenic lipid profile. While common pathogenic causes of high peritoneal transport and atherosclerosis have been hypothesized, it is more likely that CAPD as currently practiced is unsuitable for HTs, who should be switched to HD or NIPD. Renal and peritoneal clearances have different clinical effects and should be assessed separately. Current measures of dialysis adequacy, such as total Kt/V, do not therefore describe the patient's clinical situation accurately and are insufficient.

Is high peritoneal transport rate an independent risk factor for CAPD mortality?

Is high peritoneal transport rate an independent risk factor for CAPD mortality?

BACKGROUND

Patients with high peritoneal transport display the lowest serum albumin (SAlb) and the highest peritoneal protein loss. An association between high peritoneal membrane permeability and diabetes mellitus (DM) has been suggested. As malnutrition, hypoalbuminemia, and DM cause high mortality, it is probable that a high peritoneal transport rate is associated with high mortality on continuous ambulatory peritoneal dialysis (CAPD). The aim of the study was to identify whether a high peritoneal transport rate is an independent risk factor for mortality on CAPD.

METHODS

We included 167 patients with a peritoneal equilibration test that was performed between January 1994 and July 1997. The endpoint was the patient's status (alive, dead, or lost) in December 1997. Survival analysis was done by the Kaplan-Meier method and multivariate Cox proportional-hazard model.

RESULTS

DM was significantly more frequent in the high (H) peritoneal transport type (20 out of 33) and was less frequent in the low (L) transport group (3 out of 18). SAlb (g/dL) was significantly lower as the peritoneal transport type was higher [H 2.7 +/- 0.5, high average (HA) 2.9 +/- 0.7, low average (LA) 3.2 +/- 0.6, and L 3.6 +/- 0.5]. Serum creatinine (SCr) was significantly higher in the L transport type (12.0 +/- 4.3 mg/dL) than in the other transport groups (H 8.7 +/- 3.1, HA 8.6 +/- 3.7, and LA 9.6 +/- 4.5). No other differences were found between peritoneal transport types. In the univariate analysis, high peritoneal transport rate, DM, low SCr, low SAlb, and older age significantly predicted mortality. However, in the multivariate analysis (chi2 = 40.55, P < 0.0001), only DM (b = 1.34, P = 0.0001), low SCr (b = -0.11, P = 0.02), and high peritoneal transport rate (b = 2.6, P = 0.06) were shown as mortality risk factors.

CONCLUSIONS

DM was the most important risk factor for mortality on CAPD. A high peritoneal transport rate also predicted mortality, yet its role seems to be related to the presence of DM. The role of higher SCr predicting a better survival might have been associated with a better nutritional status. Hypoalbuminemia, previously shown as risk factor for mortality, did not play an important role in this study, probably because of its collinearity with DM.

Morbidity and mortality in redefining adequacy of peritoneal dialysis: a step beyond the National Kidney Foundation Dialysis Outcomes Quality Initiative

The National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF-DOQI) Peritoneal Dialysis (PD) Adequacy Work Group intentionally limited the scope of its work to address adequacy in terms of small-solute removal. This decision was based on the need for rigorous evidence and that mortality is the most objective parameter in the literature. This review attempts to more broadly redefine the concept of the adequacy of PD, particularly as it relates to the most common general medical problems that PD patients experience; namely, cardiovascular disease and malnutrition. Whereas we are sensitive to the developmental process of the NKF-DOQI, we are critical that the definition of adequacy may be too narrow, leading clinicians to overlook other important morbidities. We have reiterated the evidence that suggests a weekly solute clearance (Kt/Vurea) of 1.7 or greater is associated with better patient survival. The arguments to target a greater Kt/Vurea of 2.0 are challenged, yet the concept is ultimately supported. Because cardiovascular disease is the cause of death in half of all patients with end-stage renal disease, dialysis adequacy must be defined, in part, by the potential of that therapy to diminish cardiovascular maladies. Blood pressure, volume, left ventricular hypertrophy, and dyslipidemias are discussed in this context. Lastly, assumptions that increasing total solute clearance leads to improved nutrition in PD patients are challenged. We have attempted to expand on what the NKF-DOQI did not include, and we urge the dialysis community to seek the answers to the many controversies that remain. We need to redefine the adequacy of PD in a holistic manner and find outcome parameters that are not as final as death.

Tidal peritoneal dialysis for home-treated patients: should it be preferred?

Tidal peritoneal dialysis (TPD) was introduced to increase the efficacy of peritoneal dialysis. We measured peritoneal clearances of small solutes and beta2-microglobulin, peritoneal protein loss, and efficacy of ultrafiltration in 30 patients during TPD and intermittent peritoneal dialysis (IPD) with low-dialysate flow (1.7 L/h) and, in addition, in 17 of these patients using a high-dialysate flow (3 L/h). Using a low-dialysate flow, patients with low/low average peritoneal transport rates showed significantly better peritoneal creatinine and urea nitrogen clearances during IPD compared with TPD, whereas there was no difference between these two treatment modalities in high/high average transporters. With high-dialysate flow, peritoneal clearances of creatinine and urea nitrogen were similar between TPD and IPD independent of peritoneal transport type. Clearances of phosphate and beta2-microglobulin were similar between TPD and IPD independent of dialysate flow or peritoneal transport type. Increasing the dialysate flow rate led to a significant increase in small-solute clearances, but not beta2-microglobulin clearances, in both peritoneal transport types. Total peritoneal protein and albumin losses were similar between TPD and IPD only with low-dialysate flow. However, using a high-dialysate flow, total protein losses tended to increase in both transport types during IPD compared with TPD. In conclusion, up to a dialysate flow of 3 L/h, TPD did not provide better small-solute or middle-molecule clearances compared with IPD. Moreover, using a low-dialysate flow, IPD was superior to TPD in low/low average transporters.