Analysis of fluid transport pathways and their determinants in peritoneal dialysis patients with ultrafiltration failure.

Ultrafiltration failure (UFF) is a serious complication of peritoneal dialysis (PD). The aim of the study was to analyze changes in water transport and their determinants in UFF patients over the time on PD. Standard peritoneal permeability analyses of 50 stable PD patients with UFF were analyzed. Fluid transport through small pores (SPT), free water transport (FWT) at 60 min, their contributions on total ultrafiltration (SPTC and FWTC), and their determinants were assessed. Patients were divided in Group I (UFF) treated for less than 24 months, Group II treated 24-60 months, and Group III treated for more than 60 months. Group I (UFF) was compared with Group I (non-UFF) matched for the duration of PD treatment and age. Transcapillary ultrafiltration (TCUF), SPT, FWT, and FWTC were significantly lower in Group III when compared to the other UFF groups. In this group also, negative relationship was present between FWT, the ultrafiltration coefficient LpA, and osmotic conductance to glucose on one hand and PD duration on the other. FWT was positively related to osmotic conductance to glucose in all groups. Group I (UFF) showed significantly higher solute transport, effective lymphatic absorption rate, lower TCUF, and lower FWT than Group I (non-UFF). The patterns of UFF in PD patients are dependent on the duration of treatment.