The Relationship between Ultrafiltrate Volume with Icodextrin and Peritoneal Transport Pattern according to the Peritoneal Equilibration Test

Abstract

To establish a relationship between peritoneal transport membrane pattern, analyzed by the peritoneal equilibration test (PET), and drained volume using icodextrin (7.5% Ico) and glucose (3.86% Glu) solutions. Thirty peritoneal dialysis patients were submitted to a standard 4-hour PET and divided into 4 transport categories based on dialysate-to-plasma ratio of creatinine (D/Pcr) and dialysate ratio of glucose at 4 and zero hours of the dwell (D4/D0). Patients were asked to perform exchanges for 2 consecutive nights in 10-hour dwells (2 L 3.86% Glu solution on the first night, and 2 L 7.5% Ico solution on the second night). The drained volume was measured and dialysate samples from the overnight exchanges were obtained for beta2-microglobulin (B2M) levels. PET classification using D/Pcr showed that 46.6% of the patients were high and high-average transporters, or 23.3% when D4/D0 was used. In spite of this difference, both methods showed significant correlation (p = 0.0001, r = 0.862). The mean drained volumes were similar for both solutions (for 3.86% Glu, 2696 +/- 369 mL; for 7.5% Ico, 2654 +/- 424 mL). The high and high-average transport patients classified by D4/D0 achieved a higher ultrafiltration with 7.5% Ico than with 3.86% Glu (p = 0.0235). When classified by D/Pcr, the difference was not significant (p = 0.2243). In the low and low-average transport patients classified by D/Pcr, we observed a significantly lower ultrafiltration when 7.5% Ico was used compared to 3.86% Glu solution (p = 0.0197). Using D4/D0, we saw a tendency toward lower ultrafiltration (p = 0.0719) in the same group. We then correlated the PET results and the difference between drained volume with 7.5% Ico and 3.86% Glu solution [deltaV (I-G)]. We found a significant negative correlation between D4/D0 and deltaV (I-G) (p = 0.002, r = -0.5390), and a positive correlation between D/Pcr and deltaV (I-G) (p = 0.005, r = 0.4932). The levels of B2M obtained with 7.5% Ico were higher than those obtained with 3.86% Glu solution (for 7.5% Ico, 9.47 +/- 6.71 microg/vol; for 3.86% Glu, 7.29 +/- 4.91 microg/vol; p = 0.004). Furthermore, we found significant correlation between the total amount of B2M obtained with 7.5% Ico solution and D4/D0 (p < 0.0001, r = -0.4493), and D/Pcr (p < 0.0001, r = 0.5431). Mean drained volume was similar between the two solution groups. High transporters, as defined by D4/D0, achieved higher ultrafiltration with 7.5% Ico than with 3.86% Glu solution. This is most likely due to the higher number of small pores in the peritoneal membrane. Low transporters, as classified by D/Pcr, achieved lower ultrafiltration with 7.5% Ico than with 3.86% Glu solution. The deltaV (I-G) and the PET results showed significant correlation, confirming that high transporters have a higher ultrafiltration volume with 7.5% Ico. The total B2M mass obtained with 7.5% Ico was greater than with 3.86% Glu solution and significantly higher in the high transport patients, indicating a larger number of small pores. Thus, the deltaV (I-G) could give us an idea of the peritoneal transport pattern in peritoneal dialysis patients.