Peritoneal transport characteristics in CAPD patients are often assessed by the peritoneal equilibration test (PET), which uses a four hour dwell with glucose 2.27% dialysate. From the test, the dialysate/plasma ratio of creatinine (D/PCr), the dialysate/initial dialysate ratio of glucose (D/Do) and net ultrafiltration (NUF, drained minus instilled volume) are calculated. The standard peritoneal permeability analysis (SPA) is a modification and extension of the PET: glucose 1.36% dialysate is used, to which dextran 70 (1 g/liter) is added for the calculation of fluid kinetics. Mass transfer area coefficients (MTAC's) of low molecular weight solutes, clearances of proteins and the change in intraperitoneal volume (delta IPV) can be assessed. In this study the SPA was analyzed, and a comparison with the PET was made. A total number of 138 SPA's was analyzed in 86 different clinically stable patients. Normal values were calculated for both SPA and PET parameters in the same tests. Median (ranges) of comparable transport parameters from SPA and PET were: MTACCr, 10.4 ml/min (5.7 to 19.3); glucose absorption, 61% (35 to 87); delta IPV, 9.5 ml (-761 to 310); D/PCr, 0.76 (0.53 to 1.14); D/D0, 0.37 (0.13 to 0.56); NUF, -75 ml (-675 to 450). The agreement between SPA and PET was analyzed using the method of Bland and Altman. A fairly good agreement was present between NUF and delta IPV. Systematic errors were found when D/PCr and MTACCr were compared: D/P overestimated MTAC mainly in the low range, whereas in the high range values were underestimated. A similar pattern was seen for the transport parameters of glucose. In 40 patients negative net ultrafiltration was present, and possible reasons for this were assessed. In 9 patients no reason could be identified. It can be concluded that the SPA provides useful and extensive information on peritoneal transport parameters. Compared to the PET, the SPA has better discriminative power for the transport of glucose and creatinine.

Background The most widely used peritoneal function test, the peritoneal equilibration test (PET), is performed with a 2.27% glucose solution. Recently, the International Society for Peritoneal Dialysis committee on ultrafiltration failure (UFF) advised performing the test with 3.86% glucose solution because it is more sensitive for detecting clinically significant UFF. Because no reference values for this test were available, we analyzed the results of standard peritoneal permeability analyses (SPAs) using 3.86% glucose. Methods The tests were performed in our center on 154 clinically stable peritoneal dialysis (PD) patients that were free of peritonitis for at least 4 weeks. For the assessment of reference values, we used two approaches. In approach A, patients with UFF, defined as net ultrafiltration (UF)< 400 mL/4 hours, were excluded. In approach B, only patients within their first 2 years of PD treatment were included, regardless of net UF. Means and 95% confidence intervals (95% CI) were calculated for the transport parameters of the PET and SPA. Results Means of normal distribution with 95% CI in approach A were as follows: for 2.0-L exchanges, mass transfer area coefficient (MTAC) for creatinine 8.8 mL/minute (4.7 – 12.7 mL/min), dialysate/plasma ratio (D/P) creatinine 0.70 (0.52 – 0.88), glucose absorption 58% (44% – 72%), dialysate240/initial dialysate ratio of glucose (D t/D0) 0.28 (0.18 – 0.38), net UF 675 mL (375 – 975 mL), and maximal dip in D/P sodium after correction for diffusion from the circulation 0.110 (0.050 – 0.164); for 1.5-L exchanges, MTAC creatinine 7.4 mL/min (3.8 – 11.0 mL/min), D/P creatinine 0.69 (0.52 – 0.86), glucose absorption 62% (52% – 72%), D t/D0 glucose 0.25 (0.17 – 0.32), net UF 551 mL (430 – 670 mL), and maximal dip D/P sodium 0.120 (0.048 – 0.166). In approach B, most of the transport values were similar; however, values for lymphatic absorption were significantly higher [1.52 mL/min (2-L) and 1.40 mL/min (1.5-L), p < 0.01] and values for the maximum dip in D/P sodium were lower [0.101 (2-L) and 0.112 (1.5-L), p > 0.05]. This was probably the result of including patients with UFF in approach B, since these parameters can be causative factors of UFF. Conclusions A peritoneal transport function test using 3.86% glucose provides data on various aspects of transport. This study gives normal reference values that can be used for analysis of causes of UFF.

Background Ultrafiltration failure (UFF) is a major complication of peritoneal dialysis (PD). It can occur at any stage of PD, but develops in time and is, therefore, especially important in long-term treatment. To investigate its prevalence and to identify possible causes, we performed a multicenter study in The Netherlands, where patients treated with PD for more than 4 years were studied using a peritoneal function test (standard peritoneal permeability analysis) with 3.86% glucose. UFF was defined as net UF < 400 mL after a 4-hour dwell. Results 55 patients unselected for the presence or absence of UFF were analyzed. Mean age was 48 years (range 18 – 74 years); duration of PD ranged from 48 to 144 months (median 61 months); UFF was present in 20 patients (36%). Patients with and without UFF did not differ in age or duration of PD. Median values for patients with normal UF compared to patients with UFF were, for net UF 659 mL versus 120 mL ( p < 0.01), transcapillary UF rate 3.8 versus 2.1 mL/minute ( p < 0.01), effective lymphatic absorption 1.0 versus 1.6 mL/min ( p < 0.05), mass transfer area coefficient (MTAC) for creatinine 9.0 versus 12.9 mL/min ( p < 0.01), dialysate-to-plasma ratio (D/P) for creatinine 0.71 versus 0.86 ( p < 0.01), glucose absorption 60% versus 73% ( p < 0.01), maximum dip in D/P sodium (as a measure of free water transport) 0.109 versus 0.032 ( p < 0.01), and osmotic conductance to glucose 3.0 versus 2.1 μL/min/mmHg ( p < 0.05). As causes for UFF, high MTAC creatinine, defined as > 12.5 mL/min, or a glucose absorption > 72%, both reflecting a large vascular surface, a lymphatic absorption rate (LAR) of > 2.14 mL/min, and a decreased dip in D/P sodium of < 0.046 were identified. Most patients had a combination of causes (12 patients), whereas there was only a decreased dip in D/P sodium in 3 patients, only high MTAC creatinine in 1 patient, and only high LAR in 2 patients. We could not identify a cause in 2 patients. Both groups had similar clearances of serum proteins and peritoneal restriction coefficients. However, dialysate cancer antigen 125 concentrations, reflecting mesothelial cell mass, were lower in the UFF patients (2.79 vs 5.38 U/L). Conclusion The prevalence of UFF is high in long-term PD. It is caused mainly by a large vascular surface area and by impaired channel-mediated water transport. In addition, these patients also had signs of a reduced mesothelial cell mass, indicating damage of the peritoneum on both vascular and mesothelial sites.

Background Peritoneal function tests are performed in peritoneal dialysis (PD) patients to characterize peritoneal membrane status. A low pH/high glucose degradation product (GDP) dialysis solution is used as the test solution. The objective of the present study was to compare a 3.86% glucose, low pH/high GDP dialysis solution (pH 5.5) with a 3.86% glucose, normal pH/low GDP dialysis solution (pH 7.4) in assessments of peritoneal membrane function. Methods Two standard peritoneal permeability analyses (SPA) were performed in 10 stable PD patients within 2 weeks. One SPA was done with the 3.86% low pH/high GDP solution, and the other with the 3.86% normal pH/low GDP solution. The sequence of the two tests was randomized. Results Fluid transport parameters and glucose absorption were not different between the two groups. No differences were found for the mass transfer area coefficients (MTACs) of low molecular weight solutes calculated over the whole dwell. However, MTAC urea in the first hour of the dwell was higher in the test done with low pH/high GDP dialysate, suggesting more peritoneal vasodilation. No difference was found in protein clearances. Sodium sieving at multiple time points during the dwell was similar with the two solutions. Conclusion The results obtained with the glucose-containing normal pH/low GDP dialysis solution were similar to those obtained with the glucose-containing low pH/high GDP dialysate in assessments of peritoneal membrane function.