Peritoneal Transport Rate Research Articles

Increased Peritoneal Membrane Permeability is Associated with Abnormal Peritoneal Surface Layer

We recently showed that the peritoneal surface layer may be an important barrier in modulating peritoneal membrane permeability. In the present study, we investigated the relationship between an increased peritoneal transport rate and the peritoneal surface layer. Male Sprague-Dawley rats (n = 8) received intraperitoneal injections of 4.25% glucose dialysate daily for 1 week. Forty-eight hours after the last injection, a 4-hour dwell study using 25 mL 4.25% glucose dialysate was performed in each rat. The results were compared with those from control rats that received no intraperitoneal injections (n = 8). The peritoneal fluid and small-solute transport characteristics were evaluated. The peritoneal surface layer was studied using an electron microscope. The phospholipids content of the dialysate was also evaluated. Peritoneal fluid removal was significantly reduced in the daily injection group (30.6 +/- 1.3 mL) as compared with the control group (38.2 +/- 0.6 mL). The peritoneal fluid absorption rate and small-solute transport rate were also significantly higher in the daily injection group as compared with the control group. The amounts of phospholipids in the dialysate were significantly lower in the daily injection group--especially the quantity of phosphatidylcholine. However, lysophosphatidylcholine increased significantly in the daily injection group. Electron microscopy showed that the peritoneal surface layer was almost completely gone in the daily injection group, but that a dense and thick (average 4 microm) peritoneal surface layer was present on the top of the mesothelial cells in the control group. Our results suggest that daily injection of hypertonic glucose dialysate significantly increased the peritoneal transport rate. The increased peritoneal transport rate was associated with a significant reduction in the peritoneal surface layer and the phospholipids content of the dialysis effluent.

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

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

Peritoneal Dialysis following Failed Kidney Transplantation is Associated with High Peritoneal Transport Rates

Peritoneal Dialysis following Failed Kidney Transplantation is Associated with High Peritoneal Transport Rates

Biocompatibility of New Peritoneal Dialysis Solutions: What Can We Hope to Achieve?

Despite the bioincompatibility of the "old", standard, high glucose, lactate-buffered peritoneal dialysis (PD) solutions, PD is itself a highly successful dialysis modality with patient survival equivalent to that of hemodialysis (HD) during the initial 3 - 5 years of dialysis therapy. Nevertheless, PD technique survival is often limited by infectious complications and alterations in the structure and function of the peritoneal membrane. These local changes also have a negative impact on patient survival owing to systemic effects such as those often seen in patients with high peritoneal transport rate and loss of ultrafiltration (UF) capacity. Patient mortality remains unacceptably high in both HD and PD patients, with most premature deaths being associated with signs of malnutrition, inflammation, and atherosclerotic cardiovascular disease (MIA syndrome). These systemic signs are likely to be influenced by PD solutions both directly and indirectly (via changes in the peritoneal membrane). New, biocompatible PD solutions may have favorable local effects (viability and function of the peritoneal membrane) and systemic effects (for example, on MIA syndrome). Amino acid-based solution [Nutrineal (N): Baxter Healthcare Corporation, Deerfield, IL, U.S.A.] may improve nutritional status as well as peritoneal membrane viability. Bicarbonate/lactate-buffered solution [Physioneal (P): Baxter Healthcare Corporation] may ameliorate local and systemic effects of low pH, high lactate, and high glucose degradation products. Icodextrin-based solution [Extraneal (E): Baxter Healthcare SA, Castlebar, Ireland] may improve hypertension and cardiovascular problems associated with fluid overload and may extend time on therapy in patients with loss of UF capacity. The positive effects of each of these new, biocompatible solutions have been demonstrated in several studies. It is likely that the combined use of N, P, and E solutions will produce favorable synergies in regard to both local effects (peritoneal viability) and systemic effects (less malnutrition, inflammation, and fluid overload). Solution combination is an exciting area for clinical study in the coming years. Furthermore, dialysis fluid additives such as hyaluronan, which protects and improves the function of the peritoneal membrane, may further improve PD solutions. The new, biocompatible PD solutions represent an entirely new era in the evolution of the PD therapy; they are likely to have markedly positive effects on both PD technique and PD patient survival in coming years.

High Peritoneal Permeability Predisposes to Hepatic Steatosis in Diabetic Continuous Ambulatory Peritoneal Dialysis Patients Receiving Intraperitoneal Insulin

To evaluate hepatic fat accumulation in diabetic patients taking intraperitoneal or subcutaneous insulin treatment during continuous ambulatory peritoneal dialysis (CAPD). Cross-sectional study. Tertiary-care university hospital. We studied 16 patients with diabetic end-stage renal disease currently treated with CAPD. Median age was 42 years (range: 34-70 years), duration of diabetes was 27.5 years (range: 17-39 years), and duration of CAPD was 16.5 months (range: 2-59 months). Ultrasound measures of liver steatotic area and thickness, peritoneal equilibration test (PET), weekly Kt/V urea, protein catabolic rate (PCR), hemoglobin A1c (HbA1c), lipoproteins, alanine aminotransferase, alkaline phosphatase, insulin dose, and dialysate glucose load. Focal hepatic fat accumulation was found. The location of steatosis was subcapsular; a negligible amount was periportal. Hepatic subcapsular steatosis was present in 7 of 8 patients taking insulin intraperitoneally and in 0 of 8 patients taking insulin subcutaneously. The maximal thickness of subcapsular steatosis correlated directly with peritoneal transport rate (2-hour dialysate-to-plasma creatinine ratio in PET, r = 0.80, p < 0.05) and inversely with PCR (r = -0.82, p < 0.05). The area of the lesions correlated directly with body weight (r = 0.80, p < 0.05) and inversely with weekly Kt/V urea (r = -0.90, p < 0.01). Intraperitoneal insulin, together with glucose-based peritoneal dialysate, induces hepatic subcapsular steatosis. The amount of hepatic subcapsular steatosis increases when peritoneal transfer rate and body weight are high.

Peritoneal Transport Characteristics, Comorbid Diseases and Survival in CAPD Patients

To evaluate the influence of initial peritoneal transport rate, serum albumin concentration, and comorbid diseases on continuous ambulatory peritoneal dialysis (CAPD) patient survival. A prospective single-center study with a long-term follow-up. A total of 213 consecutive CAPD patients, who underwent a peritoneal equilibration test (PET) at a mean of 7 days (range 3 - 30 days) after beginning CAPD, were included in this study. One hundred twenty patients were male, 116 patients had comorbid diseases, and mean age was 49.5 years (range 18 - 76 years). A modified PET was performed using 4.25% glucose dialysis solution. Based on the dialysate-to-plasma creatinine concentration ratio at 4 hours' dwell (D4/P4 Cr, 0.62 +/- 0.14), patients were divided into high (H), high-average (HA), low-average (LA), or low (L) transporters. Of 213 patients, 16.9% were classified as H transporters, 30.5% as HA, 36.6% as LA, and 16.0% as L transporters. The H transporter group had a higher proportion of men, higher proportion of patients with comorbid diseases, lower initial serum albumin concentration, lower D4/D0 glucose, and lower drained volume. The initial D4/P4 Cr correlated with initial serum albumin (r= -0.35, p < 0.001). The patients with comorbid diseases had lower initial serum albumin and higher initial D4/P4 Cr. On Kaplan-Meier analysis, 2-year patient survival of group H was significantly lower compared to the other groups combined (57.1% vs 79.5%, p = 0.009). On Cox proportional hazards analysis, age, comorbid diseases, initial serum albumin concentration, and initial D4/P4 Cr were found to be independent risk factors for mortality. However, in the patients without comorbid diseases, patient survival was not different between group H and the other transport groups combined (p > 0.05), and only age was found to be an independent risk factor for mortality. These data suggest that a high peritoneal transport rate at initial PET is associated with high mortality, and that this is in part due to an increased prevalence of comorbid disease in H transporters. These H transporters with comorbid diseases represent a subset of patients with an especially poor prognosis. In patients without comorbid diseases, high transport status or low serum albumin concentration was not an independent risk factor for mortality.

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

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

Effect of Pyrazinamide and Probenecid on Peritoneal Urate Transport Kinetics during Continuous Ambulatory Peritoneal Dialysis

We administered pyrazinamide (PZA) and probenecid (PB) --two well-known modulators of urate transport via the proximal tubules - to evaluate their impact on urate transport through the peritoneal membrane and to clarify mechanisms affecting peritoneal transport. A continuous ambulatory peritoneal dialysis (CAPD) unit in 2nd Hospital of IKA (Social Services Institute), Greece. In 20 stable CAPD patients, on the study day, a 4-hour, 2-L, 1.36% glucose exchange was performed (control exchange). Pyrazinamide 3 g was given orally and another identical exchange was performed (study exchange). The same protocol was repeated with 2 g PB. KtN, peritoneal clearances of urea, creatinine, and urate for each exchange, and mass transfer area coefficients (MTAC) for the three solutes and their dialysate-to-plasma concentration (D/P) ratios were used to estimate peritoneal transport. Administration of PZA resulted in decreased clearances and MTAC values for the three solutes. The D/P ratio decreased significantly only for urate, indicating a more intense influence of PZA on urate. After PB administration, clearances of urea, creatinine, and urate were increased. MTAC and DIP ratio increased significantly only for urate (p < 0.05), demonstrating an action similar to that exerted on renal tubules. These findings provide evidence that unrestricted diffusion is not the only transport mechanism in the case of urate, and demonstrate the existence of an active mechanism in peritoneal urate transport with a reabsorptive and, probably, a secretive component that resembles that of renal tubule urate transport. Attention should be given in the case of CAPD patients undergoing antituberculous (PZA) treatment: it might have a negative impact on urea, creatinine, and urate peritoneal transport rates.

Influence of the preceding exchange on peritoneal equilibration test results: a prospective study.

The standard peritoneal equilibration test (PET) should be performed after a long overnight dwell, which is easily possible in continuous ambulatory peritoneal dialysis patients. However, for such a procedure, patients undergoing automated peritoneal dialysis or daily ambulatory peritoneal dialysis have to change their regimen and, in the case of high peritoneal transport rates, run the risk for fluid absorption. We compared dialysate to plasma ratios (D/P) of creatinine, blood urea nitrogen (BUN), phosphate, sodium, total protein, and albumin measured during PET after an 8- to 11-hour dry period (PET dry), after a preceding exchange with a long dwell time (PET standard), and immediately after tidal peritoneal dialysis (PET tidal). D/P ratios of creatinine, BUN, phosphate, and sodium at 2 and 4 hours were greater during PET dry compared with both PET standard and PET tidal. The quotient of dialysate glucose at 2 hours to dialysate glucose at time point 0 was significantly less in PET dry compared with both PET tidal and PET standard. During the first 2 hours of PET, the increase of D/P curves of creatinine and BUN, as well as phosphate, was significantly steeper in PET dry than PET tidal and PET standard. D/P ratios of albumin and protein were greatest in PET dry and least in PET tidal. There was a significant difference between all three PETs at 0, 2, and 4 hours of dwell time. PET curves were significantly steeper during PET dry compared with PET tidal in case of D/P protein (during the first 2 hours of dwell time) and D/P albumin (during the entire dwell time). Similar differences between the PET curves of protein and albumin were observed between PET dry and PET standard. These data clearly indicate a dry period before PET significantly influences the D/P ratios of small solutes, protein, and albumin measured during the test.

Peritoneal dialysis adequacy: A model to assess feasibility with various modalities

The current standard of adequacy for peritoneal dialysis (PD) is to provide a weekly normalized urea clearance (Kt/V) of 2.0 or more and a creatinine clearance (CCr) of 60 liter/1.73 m2 or more. As native renal function is lost, it is important to determine the effectiveness of the available therapeutic modalities in achieving these goals. A model to assess our ability to provide a weekly Kt/Vurea of 2.0 or more and a CCr of 60 liter/1.73 m2 or more to anuric patients undergoing continuous ambulatory PD (CAPD) and automated PD (PD Plus) was developed. The body surface area (BSA) distribution was obtained from 38,768 patients undergoing dialysis during January 1997. The distribution of peritoneal transport rates (PTRs) was obtained from 2531 peritoneal equilibration tests performed during 1996. The weekly Kpt/Vurea was calculated for the various PTR groups and the range of BSA with four PD prescriptions: CAPD 8 liters, CAPD 10 liters, PD Plus 12 liters, and PD Plus 15 liters, using a previously validated kinetic program (PackPD). The predicted percentage of patients capable of achieving the adequacy goals for Kt/V and CCr, respectively, were 24.8 and 11. 2 for CAPD 8 liters, 54.2 and 33.0 for CAPD 10 liters, 77.8 and 54.9 for PD Plus 12 liters, and 93.2 and 72.9 for PD Plus 15 liters. Most patients can attain the current adequacy standards of therapy with automated PD, but few (less than 25%) can do so with standard CAPD in the absence of residual renal function.

Associates of mortality among peritoneal dialysis patients with special reference to peritoneal transport rates and solute clearance.

The current report describes the distributions of selected demographic and biochemical parameters, clearance, and other transport values among patients undergoing peritoneal dialysis (PD) and evaluates the associates of mortality using those values, with and without clearance and peritoneal equilibration test (PET) data. All patients receiving PD on January 1, 1994 were selected (n = 2,686). Patients who switched to another form of dialysis during the study period were removed from the study at the time of therapy change. Working files were constructed from the clinical database to include demographic, laboratory, and outcome data. Laboratory data were available in only 1,603 patients and were used to evaluate the biochemical associates of mortality after merging the biochemical, demographic, and outcome data. Patients with clearance data or PET studies underwent a second analysis to assess the effects of peritoneal and renal clearance on survival. The analysis of demographic and laboratory data confirmed the importance of age and serum albumin concentration as predictors of death. Residual renal function (RRF) was strongly correlated with survival, but peritoneal clearance was not. Several possible explanations for the lack of correlation between peritoneal clearance and survival are discussed. The data suggest that RRF and peritoneal clearance may be separate and not equivalent quantities. Substantial work is required to confirm or refute these findings, because the information is essential to establish the adequate dose of PD in patients with various degrees of RRF.

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.

Analysis of the Peritoneal Equilibration Test in Mexico and Factors Influencing the Peritoneal Transport Rate

To validate the peritoneal equilibration test (PET), establish reference values in the Mexican population, compare our results with those reported by Twardowski et al., and analyze the influence of some factors on the peritoneal transport rate (PTR). Retrospective, cross-sectional study. Eighty-six PETs were performed in 45 female and 41 male patients; 35 of the patients were diabetics. Creatinine D/P and glucose D/D0 ratios were calculated and compared with those from Twardowski et al. In a multivariate analysis, age, gender, diabetes mellitus (DM), time on dialysis, and peritonitis rate were considered as independent factors influencing the PTR. Creatinine D/P and glucose D/D0 ratios at 4 hours were not significantly different from those reported by Twardowski et al. Creatinine D/P at 4 hours was not different between DM and non-DM patients when the rate of peritonitis and time on dialysis were not taken into account. Multivariate analysis did not result in any significant model predicting the creatinine D/P at 4 hours. PET validation is reported for the first time in a Latin American population. The PET results of this study are similar to those in the literature. We found that DM, peritonitis rate, time on dialysis, age, and gender did not clearly influence the PTR.

Does a High Peritoneal Transport Rate Reflect a State of Chronic Inflammation?

It has recently been reported that a high peritoneal transport rate was associated with increased mortality in continuous ambulatory peritoneal dialysis (CAPD) patients. One possible explanation is that a high peritoneal transport rate might be caused by a state of chronic inflammation, which also per se might result in increased mortality. Therefore, in this study we investigated whether high peritoneal transport rate patients are in a state of chronic inflammation. The study included 39 clinically stable peritoneal dialysis patients (free of peritonitis) who had been on PD for more than 3 months (16.8+/-11.8 months). Seven patients were treated with continuous cycling peritoneal dialysis (CCPD) and the others were on CAPD. A 4-hour standard peritoneal equilibration test (PET) using 2.27% glucose solution was performed in each patient. Dialysate samples at 4 hours and blood samples at 2 hours were measured for interleukin-1beta (IL-1beta), tumor necrosis factor(alpha)(TNFalpha), C-reactive protein (CRP), and hyaluronan as markers of inflammation. There was no significant correlation between dialysate/plasma (DIP) creatinine (0.82+/-0.15, range 0.51 - 1.15) and blood concentrations of IL-1beta (11.2 ng/L, range <5 - 65.9 ng/L),TNFalpha (12.1 ng/L, range <5 - 85.4 ng/L), CRP (<10 mg/L, range <10 - 76 mg/L), nor with the blood hyaluronan concentration (165 microg/L, range 55 - 955 microg/L). The dialysate concentrations of IL-1beta and TNFalpha were below the detectable level in most of the samples. Although dialysate hyaluronan concentration (334 microg/L, range 89 - 1100 microg/L) was correlated with D/P creatinine (r= 0.36, p< 0.05), there was no correlation between the total amount of hyaluronan in the effluent and D/P creatinine. However, a significant correlation was found between serum hyaluronan concentration and glomerular filtration rate (GFR) (r = -0.49, p< 0.005); GFR also tended to be correlated with serum TNFalpha (r = -0.31, p = 0.058) but not with serum IL-1beta and serum CRP. Our results suggest that a high peritoneal transport rate is not necessarily related to a state of chronic inflammation in CAPD patients. The high mortality rate observed in high transporters may relate to other issues, such as fluid balance or abnormal nutrition and metabolism, rather than to chronic inflammation.

Provision of optimal dialysis for peritoneal dialysis patients

Prescription of optimal dialysis is of major importance in determining the overall prognosis and nutritional status of patients receiving chronic peritoneal dialysis (PD). A mathematical model of peritoneal dialysis kinetics was used to examine typical dialysis prescriptions for patients receiving continuous ambulatory peritoneal dialysis (CAPD) or automated peritoneal dialysis (APD), and using a new automatic night‐time dialysis machine. Based on the recommendations of the CANUSA and other studies, a creatinine clearance delivery target of 70 L per week (the equivalent of 6.9 mL/min) was selected. At the start of dialysis, creatinine clearances of greater than 70 L/week are achieved in most patients on PD, but by 2 years deterioration of residual renal function (RRF) results in standard dialysis prescriptions of 4×2 L exchanges per day providing adequate solute clearance to only a minority of patients. Prescriptions of 4×2.5 or 4×3.0 L exchanges per day may be required to provide optimal solute clearance to most patients without RRF. Automated peritoneal dialysis, especially when prescribed without day‐time fluid, often delivers inadequate solute clearance. In order to achieve optimal solute clearance with APD it is essential that patients have dialysate in the abdomen by day, and most need to perform a mid‐day exchange. Five exchanges per day can be easily achieved, using the new technology that performs a night‐time exchange, and this often results in optimal solute clearance. Optimization of dialysis prescriptions may be expected to result in improvement in objective measures of morbidity and mortality. For the individual patient, it is essential to take into account the creatinine clearances achieved with the dialysis prescribed, the body surface area, peritoneal transport rates and the contribution of measured residual renal function.

Provision of optimal dialysis for peritoneal dialysis patients

SUMMARY: Prescription of optimal dialysis is of major importance in determining the overall prognosis and nutritional status of patients receiving chronic peritoneal dialysis (PD). A mathematical model of peritoneal dialysis kinetics was used to examine typical dialysis prescriptions for patients receiving continuous ambulatory peritoneal dialysis (CAPD) or automated peritoneal dialysis (APD), and using a new automatic night‐time dialysis machine. Based on the recommendations of the CANUSA and other studies, a creatinine clearance delivery target of 70 L per week (the equivalent of 6.9 mL/min) was selected. At the start of dialysis, creatinine clearances of greater than 70 L/week are achieved in most patients on PD, but by 2 years deterioration of residual renal function (RRF) results in standard dialysis prescriptions of 4 × 2 L exchanges per day providing adequate solute clearance to only a minority of patients. Prescriptions of 4 × 2.5 or 4 × 3.0 L exchanges per day may be required to provide optimal solute clearance to most patients without RRF. Automated peritoneal dialysis, especially when prescribed without day‐time fluid, often delivers inadequate solute clearance. In order to achieve optimal solute clearance with APD it is essential that patients have dialysate in the abdomen by day, and most need to perform a mid‐day exchange. Five exchanges per day can be easily achieved, using the new technology that performs a night‐time exchange, and this often results in optimal solute clearance. Optimization of dialysis prescriptions may be expected to result in improvement in objective measures of morbidity and mortality. For. the individual patient, it is essential to take into account the creatinine clearances achieved with the dialysis prescribed, the body surface area, peritoneal transport rates and the contribution of measured residual renal function.

Peritoneal transport kinetics correlate with serum albumin but not with the overall nutritional status in CAPD patients

The present study evaluates the influence of the peritoneal transport rate (PTR) on the nutritional status of continuous ambulatory peritoneal dialysis (CAPD) patients. Additionally, protein intake, dialysis adequacy, and other clinical variables were analyzed. Forty-two CAPD patients were concurrently subjected to the peritoneal equilibration test, a nutritional evaluation that included 24-hour dietary recall, and nutritional scoring system that included anthropometric, biochemical, and subjective parameters. Eight patients were high, 14 were high-average, 16 were low-average, and four were low transporters. Nine patients had normal nutritional status; six had mild, nine had moderate, and 18 had severe malnutrition. Malnutrition was inversely correlated ( P < 0.05) with body surface, hemoglobin, and residual renal function, but not with PTR ( r = 0.14; P = 0.38). In the multivariate analysis, the nutritional status was not predicted by the PTR, protein intake, or dialysis adequacy variables. When serum albumin (SA) level was evaluated as an isolated nutritional indicator, the most significant predictors were dialysate to plasma creatinine ratio at 4 hours (D/P4), body surface area, age, and diabetes mellitus. High transporters receiving a high dose of dialysis displayed a trend of having lower SA levels, whereas low-average transporters receiving a high dose of dialysis showed a trend of have higher SA levels. In conclusion, there was no correlation between PTR and nutritional status. In the multivariate analysis, no association was found between nutritional status and PTR, dialysis adequacy, and protein intake. The best predictors for SA are PTR, body surface area, age, and diabetes mellitus.

Peritoneal dialysis prescription: the “Clearance Peak” model

Creatinine clearance (CRCL) was studied in 20 patients on CAPD in relation to the dwell times (DT), in order to establish a personalised dialysis schedule with the best clearance (CL) results, while respecting the patient's life-style. By calculating the CRCL from the two exchanges with dwell-times of 4 and 8 hours (2 I, 2.27%), curves (2nd degree polynomial regression) were plotted with three points (0h, 4h, 8h) for CRCL and the ultrafiltration rate (UF) as a function of the DT. The DT corresponding to the CRCL peak (CLPeak-time) was calculated for each subject with the first derivative of the function. On the basis of the CRCL obtained with the three most common DT (4h, 6h, 8h), we divided the patients into three categories (CLPeak-time < 5h: "fast", 5-7h: "normal"; > 7h: "slow") for the best CRCL correspondence of the 4h, 6h or 8h exchanges respectively. Also the 8h/4h ratio was used to determine CLPeak-time. For each of the three categories there is a corresponding dialysis schedule for the best CRCL and UF results of the exchanges with DT of 4, 6 and 8 hours, plus the theoretical calculation of the daily CRCL obtainable ("fast": APD; "normal": CAPD 4 exchanges/DAPD 4 exchanges; "slow": CAPD 4 exchanges). The "CLPeak" dialysis prescription model therefore identifies the most advantageous DT for each patient by using the CRCL values of two 2.27% exchanges of 4 and 8h respectively. Functional classification into three categories may give a rational orientation to dialysis prescription in order to reach the maximum CRCL possible with the individual peritoneal transport rates.

The place for cycler-assisted peritoneal dialysis in geriatric patients: comparison with hemodialysis

This study was designed to assess the place for cycler assisted peritoneal dialysis (CCPD) in the treatment of the elderly. The study population included 542 hemodialysis (HD) and 160 CCPD patients, including 206 HD and 60 CCPD patients older than 60 years of age. Physical activity (evaluated by the Karnofsky scale), risk of hospitalization, risk of death, subjective evaluation of health status (Nottingham Health Profile), peritonitis rate and peritoneal transport rates were evaluated. The incidence of peritonitis and solute transport rates among elderly and younger CCPD patients were similar. Physical activity scores were consistently lower among the elderly patients without differences between HD and CCPD. No apparent differences in the subjective assessment of physical health was seen between the elderly on HD and CCPD. Sixty percent of the elderly CCPD patients required partner assistance. The relative risk of hospitalization, risk of death and risk of discontinuation of therapy were higher for the elderly patients (p<0.05), without significant differences between HD and CCPD patients. No significant differences in the transfer rate to other therapy were seen between the elderly undergoing HD and CCPD.

Evaluation of the Peritoneal Equilibration Test in Children on Chronic Peritoneal Dialysis

The peritoneal equilibration test (PET) is routinely performed in adults treated with chronic peritoneal dialysis to assess the peritoneal transport rate and to optimize treatment prescription. Only a few and not well-standardized studies on the PET have been reported in children. Twenty-six PET's were performed in 16 children, mean age 10.9 +/- 4.9 years, mean body weight (BW) 26.8 +/- 11.9 kg, treated with nightly intermittent peritoneal dialysis (NIPD). The PET was performed according to Twardowski. Forty mL/kg BW of 2.27% glucose solution were infused at a rate of 10 mL/kg BW every 2 minutes. In the simplified test, dialysate samples were taken at dwell times 0, 2 and 4 hours for glucose and creatinine. A blood sample was taken after a 2-hour dwell time for the same parameters. The standard PET (8 patients) consisted of dialysate samples at 0, 15, 30, 60, 120, and 240 minutes and blood samples at 0 and 240 minutes. Mean D/P ratio for corrected creatinine and D/D0 ratio for glucose at 2 hours were 51.6 +/- 11.6 and 50.4 +/- 9, respectively; at 4 hours 69.6 +/- 12 and 34.4 +/- 9.8, respectively. There was good correlation between D/P creatinine and D/D0 glucose at 4 hours (p < 0.0001). Patients were classified as high (3 cases), high-average (5), low-average (6), and low (2) transporters. A statistically significant difference was found between the curves obtained by the simplified PET and those of the standard PET in the first hour (r = 0.66; p < 0.05). In conclusion, the PET, modified for use in children, gave reliable and reproducible results.(ABSTRACT TRUNCATED AT 250 WORDS)