Peritoneal Dialysis Regimen Research Articles

Evaluation of the PD Adequest Program in Japanese Patients on Peritoneal Dialysis

To perform adequate peritoneal dialysis, it is necessary to individualize the dialysis regimen. PD Adequest is a software program based on the three-pore model that can be used to predict solute clearance and ultrafiltration volume during peritoneal dialysis. We evaluated the ability of this program to predict the solute clearance and ultrafiltration volume in Japanese patients on peritoneal dialysis. The weekly creatinine clearance and weekly urea Kt/V were determined in 45 patients. The PD Adequest was used to simulate their current dialysis regimens and the predicted values of these parameters were calculated. Strong positive correlations were obtained between the actual and predicted weekly creatinine clearance (r = 0.993) and weekly urea Kt/V (r = 0.991). In conclusion, this program is potentially useful for designing peritoneal dialysis regimens in Japanese patients, even though they have a smaller body mass than Canadians and Americans for whom it was designed.

Measurement of Continuous Ambulatory Peritoneal Dialysis Prescription Adherence Using a Novel Approach

The purpose of the study was to test a novel approach to monitoring the adherence of continuous ambulatory peritoneal dialysis (CAPD) patients to their dialysis prescription. A descriptive observational study was done in which exchange behaviors were monitored over a 2-week period of time. Patients were recruited from an outpatient dialysis center. A convenience sample of patients undergoing CAPD at Piedmont Dialysis Center in Winston-Salem, North Carolina was recruited for the study. Of 31 CAPD patients, 20 (64.5%) agreed to participate. Adherence of CAPD patients to their dialysis prescription was monitored using daily logs and an electronic monitoring device (the Medication Event Monitoring System, or MEMS; APREX, Menlo Park, California, U.S.A.). Patients recorded in their logs their exchange activities during the 2-week observation period. Concurrently, patients were instructed to deposit the pull tab from their dialysate bag into a MEMS bottle immediately after performing each exchange. The MEMS bottle was closed with a cap containing a computer chip that recorded the date and time each time the bottle was opened. One individual's MEMS device malfunctioned and thus the data presented in this report are based upon the remaining 19 patients. A significant discrepancy was found between log data and MEMS data, with MEMS data indicating a greater number and percentage of missed exchanges. MEMS data indicated that some patients concentrated their exchange activities during the day, with shortened dwell times between exchanges. Three indices were developed for this study: a measure of the average time spent in noncompliance, and indices of consistency in the timing of exchanges within and between days. Patients who were defined as consistent had lower scores on the noncompliance index compared to patients defined as inconsistent (p = 0.015). This study describes a methodology that may be useful in assessing adherence to the peritoneal dialysis regimen. Of particular significance is the ability to assess the timing of exchanges over the course of a day. Clinical implications are limited due to issues of data reliability and validity, the short-term nature of the study, the small sample, and the fact that clinical outcomes were not considered in this methodology study. Additional research is needed to further develop this data-collection approach.

Replacement of Amino Acid and Protein Losses with 1.1% Amino Acid Peritoneal Dialysis Solution

Losses of nutrients into dialysate may contribute to malnutrition. Peritoneal dialysis (PD) patients are reported to lose 3-4 g/day of amino acids (AAs) and 4-15 g/day of proteins. The extent to which one exchange with a 1.1% AA dialysis solution (Nutrineal, Baxter, Deerfield, IL, U.S.A.) offsets these losses was investigated in a 3-day inpatient study in 20 PD patients. Simple, open-label, cross-over study on consecutive days in a clinical research unit. On day 1 all patients were given a peritoneal equilibration test (PET). On day 2 they received 1.5% dextrose Dianeal (Baxter) as the first exchange of the day and their usual regimen thereafter. On day 3, the first exchange of the day was the 1.1% AA solution in place of 1.5% Dianeal and the usual PD regimen thereafter. On days 2 and 3 all dialysate effluent was collected and analyzed for AAs and proteins. Patients were maintained on a constant diet. Losses of AAs and total proteins on day 2 were 3.4 +/- 0.9 g and 5.8 +/- 2.4 g, respectively, totaling 9.2 +/- 2.7 g. The net uptake of AAs on day 3 was 17.6 +/- 2.6 g (80 +/- 12% of the 22 g infused). Mean gains of AAs on day 3 exceeded losses of proteins and AAs on day 2, p < 0.001. Losses of total proteins, but not losses of AAs, and the net absorption of AAs from the dialysis solution were correlated directly with peritoneal membrane transport characteristics, obtained from the PET. Daily losses of AAs and proteins into dialysate are more than offset by gains of AAs absorbed from one exchange with 1.1% AA-based dialysis solution. Net gains of AAs exceeded losses of proteins and AAs in all patients studied. The difference was relatively constant across a wide range of membrane transport types. Net AA gains were approximately two times the total AA and protein losses.

Body Surface Area Limitations in Achieving Adequate Therapy in Peritoneal Dialysis Patients

To estimate the maximal body surface area (BSA) at which anuric chronic peritoneal dialysis patients can achieve adequate peritoneal dialysis using a variety of continuous ambulatory peritoneal dialysis (CAPD) and cycler regimens. Adequate dialysis was defined as a creatinine clearance of either 60 L/week/1.73 m2 or 70 L/ week/1.73 m2. Calculation of daily peritoneal creatinine clearances using standard formulas. For CAPD patients, creatinine clearance was calculated using published values for dialysate-to-plasma ratios for creatinine (D/P cr) measured over a 24-hour period and assuming a daily ultrafiltration rate of 1.5 to 2.0 L/day. For cycler patients, creatinine clearance was calculated for both one- and two-hour dwell volumes, using published values for D/P cr from the peritoneal equilibration test and assuming a daily ultrafiltration rate of 2.0 L/day. All clearances were corrected to a normalized body surface area of 1.73 m2. For CAPD patients, 2-L dwell volumes can provide a weekly creatinine clearance of 60 L/week/1.73 m2 in patients with BSA < 1.45 m2 in the high transporter group and with BSA < 1.2 m2 in the low-average transporter group. Increasing dwell volume from 2.0 to 2.5 L increases these BSA limits in the four transport groups by 0.2-0.3 m2. Cycler therapy is not a viable option for patients in the low transporter group, and this therapy can achieve adequate creatinine clearances in patients in the low-average transport group only with large dwell volumes and in patients with BSA < 1.55 m2. However, in the high-average and high transporter groups, cycler therapy provides for superior creatinine clearances compared to CAPD patients using similar dwell volumes. Adequate creatinine clearances in anuric patients are most likely to be achieved in patients with BSA > 2.0 m2 if they have high-average or high transport characteristics and are receiving cycler therapy with large dwell volumes and at least one daytime dwell. However, adequate creatinine clearances may be difficult to achieve in anuric patients who have a large BSA and a low or low-average transport type, regardless of peritoneal dialysis modality. These patients should be considered for either high-dose peritoneal dialysis (multiple daytime and nighttime exchanges) or hemodialysis therapy.

The effect of improved dialytic efficiency on measures of appetite in peritoneal dialysis patients

The purpose of this study was to examine the effect of increasing urea clearance on measures of appetite and protein intake in continuous ambulatory peritoneal dialysis patients. Parameters evaluated included serum albumin normal protein catabolic rate (nPCR), visual analog scales, and tests meals monitored by a computerized system VIKTOR. Patients were studied at baseline, then at 2 months after their peritoneal dialysis (PD) regimens were intensified to increase their weekly Kt V to twice their baseline value or 3.0 (phase II), and then 2 months after being returned to their initial PD regimen (phase III). Ten patients completed follow-up. The mean Kt V at baseline, phase II, and III were 1.74 ± .11, 2.81 ± .26, and 1.85 ± .15 ( P < .0001). The mean nPCR was .85 ± .06 g/kg/d at baseline, 1.08 ± .09 g/kg/d in phase II, 0.85 ± .04 g/kg/d in phase III ( P = .001). The mean serum albumin was 3.89 ± .15 g/dL at baseline, 4.07 ± .17 g/dL after phase II, and 3.93 ± 0.16 g/dL after phase III ( P > .05). Parameters of appetite measured by the monitored test meals and visual analog scores showed no changes over the study period. We have found that improving urea clearance in PD patients led to an increase in protein intake as measured by nPCR, but no change in specific measures of appetite.

The Use of Glucose Polymer (Icodextrin) in Peritoneal Dialysis: An Overview

The osmotic effectiveness of glucose polymer is now well established. The relative inertness of this macromolecular compound has been the key factor in its success as the first "colloid" osmotic agent in clinical use. In its present form it sustains ultrafiltration for up to 12 hours, and a daily overnight use would obviate the need for hypertonic exchanges, especially 3.86% glucose. In addition, it could be used in automated peritoneal dialysis regimens to enhance ultrafiltration and solute clearance during the daytime. Preliminary reports also indicate that it is beneficial in diabetic patients and in some patients who have lost ultrafiltration. Although systemic accumulation of glucose polymer breakdown products occurs, it reaches steady-state levels quickly (within 2 weeks) and remains stable throughout the duration of polymer use. In the long-term study these levels of maltose and oligosaccharides over 2.5 years represent the longest exposure of these substances in uremic patients without any clinical or metabolic adverse effects and provides important evidence of its safety. Future work based on ongoing studies suggests that a family of physiological solutions ("bimodal" preparations in iso-osmolar combination) could be available, and the individual's dialysis prescription could be tailored to take into account the ultrafiltration and metabolic needs. Icodextrin will be a key component of such solutions.

Factors limiting the erythropoietin response in rapidly growing infants with congenital nephrosis on a peritoneal dialysis regimen after nephrectomy

To prevent anemia in seven small children with congenital nephrotic syndrome of the Finnish type (age range 1 to 4 years), we gave recombinant human erythropoietin in a dose up to 150 IU/kg/per week. We then studied the limiting factors during 14 weeks. On a peritoneal dialysis regimen after nephrectomy, the patients grew considerably (range +0.1 to 2.2 kg/14 wk; mean + 1.3 kg/14 wk). The amount of blood taken for laboratory studies was estimated. Although the estimated erythrocyte volume increased, the improvement was masked in most patients by enhanced growth. In two patients the target hemoglobin value of 10 gm/dl was reached, and in three patients transfusions were avoided. The reticulocyte count rose in dose-dependent fashion. In five patients protein malnutrition was not prevented, although intake of protein was as recommended. The gradual decrease in serum ferritin values indicated that mobilization of iron stores was adequate. Serum iron values decreased, although in general remaining within normal limits. In six patients the serum copper concentration was low and in two the serum aluminum concentration was slightly elevated. Two patients had several episodes of infection. We conclude that in rapidly growing infants and small children receiving peritoneal dialysis after nephrectomy, the maintenance or elevation of the hemoglobin concentration depends on several limiting and coinciding factors. We speculate that, when protein is limited, body growth has priority over erythropoiesis. A higher dose of erythropoietin might have evoked a better response in hemoglobin concentration but might also have resulted in progression of the protein deficit.

Peritoneal Dialysis Glossary III

Peritoneal dialysis regimens, flow techniques, and prescriptions are presented as drawings depicting intraperitoneal fluid volumes versus time. The following terms are illustrated: (1) continuous, intermittent, and tidal flow techniques; (2) standard intermittent and continuous regimens; (3) alternate prescriptions of continuous ambulatory and continuous cyclic peritoneal dialysis; and (4) intermittent and tidal nightly peritoneal dialysis.

Calcium Carbonate as a Phosphate Binder: Is There a Need to Adjust Peritoneal Dialysate Calcium Concentrations for Patients Using CaCO3?

The widespread use of calcium carbonate as a phosphate binder is limited by its tendency to develop hypercalcemia in some patients using effective dosages needed to control hyperphosphatemia. Most common continuous ambulatory peritoneal dialysis (CAPD) regimens using dialysis solutions containing 3.5 mEq/L of calcium result in net absorption of calcium from the dialysis solution and, hence limit the amount of oral calcium that can be administered. Peritoneal dialysis solutions with reduced calcium levels are needed for effective use of CaCO3 to control hyperphosphatemia in some dialysis patients.

The Peak Concentration Hypothesis: A Urea Kinetic Approach to Comparing the Adequacy of Continuous Ambulatory Peritoneal Dialysis (CAPD) and Hemodialysis

The KT/V urea index (K, clearance; T, treatment time; V, volume of urea distribution) has become an established index of hemodialysis (HD) adequacy, values of KT/V less than 0.8 being associated with overt uremic toxicity. For the typical continuous ambulatory peritoneal dialysis (CAPD) regimen of 4 X 2 L exchanges/day, the equivalent KT/V approximately 0.6. Paradoxically, overt uremic toxicity is not commonly observed in CAPD patients with this typical therapy prescription. Application of the urea kinetic model demonstrates that HD and CAPD have the same time-averaged urea concentration at the same KT/V. However, as HD is an intermittent therapy, the urea concentration in HD exceeds the time-averaged concentration for about half the hours in the week. If uremic toxicity is related to the peak rather than the time-averaged urea concentration, a higher KT/V would be required in HD to achieve a peak concentration at or below the steady-state CAPD concentration. This peak concentration hypothesis predicts, based on the results of the National Cooperative Dialysis Study, that underdialysis with CAPD would occur at KT/V less than 0.4 for a protein intake of 1.1 gm/kg/day.

Peritoneal Clearances with Different Dialysis Regimens in Children Undergoing Continuous Cycling Peritoneal Dialysis

Peritoneal clearances and dialysate protein losses occurring in paediatric patients undergoing different continuous cycling peritoneal dialysis (CCPD) regimens have not been well defined. We, therefore, evaluated 10 children aged 15.8 +/- 2.5 (SD) years who were maintained on home peritoneal dialysis for 20.5 +/- 10 months. All patients had at least 3 months of CCPD. The patients were admitted to the Clinical Research Center for 48 hours and allocated to five different dialysis protocols. In protocol I, the frequency of exchanges was 10 per 10 hours; in Protocol II it was 5 per 10 hours; and in Protocol III it was 3 per 10 hours. Protocol II D and III D had, in addition, a daytime dwell of one-half the night-time volume. A 1.5% glucose dialysate solution was used for night-time dialysis, and 4.25% glucose dialysate solution for the daytime dwell. The mean inflow dialysate volume per exchange was 36.7 +/- 5.6 ml/kg body weight and was constant in each patient for each study protocol. BUN and creatinine clearances for each protocol were calculated and dialysate protein losses were measured. The data indicate that hourly night-time dialysis (Protocol I) provides best solute clearance. A daytime dwell further enhances the total solute clearance and should be used preferably in anuric patients. Residual urine output contributes significantly to the total solute clearance. Protein losses are maximum with low-frequency exchanges and a daytime dwell. No significant differences in the serum albumin concentrations were found during the different protocols; however, the long-term effect of the protein loss on the nutritional status of the patients requires further evaluation.

Peritoneal Dialysis Glossary II

Peritoneal dialysis regimens, flow techniques, and prescriptions are presented as drawings depicting intraperitoneal fluid volumes versus time. The following terms are illustrated: (1) continuous, intermittent, and tidal flow techniques; (2) standard intermittent and continuous regimens; (3) alternate prescriptions of continuous ambulatory and continuous cyclic peritoneal dialysis; and (4) intermittent and tidal nightly peritoneal dialysis.