P1140THE REDUCTION OF THE SIEVING OF SODIUM IS THE FIRST AND EARLY FUNCTIONAL CHANGE OF PERITONEAL MEMBRANE IN A LARGE PATIENT POPULATION ON PERITONEAL DIALYSIS
Authors: La Milia Vincenzo , Cabiddu Gianfranca , Vizzardi Valerio , Cavalli Andrea 
Published: June 2020

Abstract

Background and Aims
The reduction whit time of peritoneal removal of salt and water is an important cause of reduced patient and technique survival in peritoneal (PD) patients. Solute transport increase after the start of PD and continue to increase throughout the course of treatment. Fast peritoneal transport results in ultrafiltration (UF) failure (UFF). UFF is due to the more rapid absorption on glucose, with a loss of the osmotic driving force for UF, and to reduction in osmotic conductance of the peritoneal membrane. The free water transport (FWT), through the aquaporin-1 channels, is about 45% of the total peritoneal UF during a dwell with a hypertonic glucose solution. It has suggested that the reduction of the FWT is due to the peritoneal fibrosis. The peritoneal sieving of sodium (Na) is a decrease (Δ) of the dialysate Na concentration during a peritoneal dwell with a hypertonic solution due to FWT. ΔNa, an indirect measure of the FWT, is maximum after 1 hour of a peritoneal equilibration test (PET) with a 3.86% glucose solution (3.86%-PET).
The aim of this study was to evaluate the functional changes of the peritoneal membrane, assessed by the PET-3.86%, in a large patient population on peritoneal dialysis (PD) followed for a long period of time.

Method
We evaluated the PET-3.86% in a large population of incident PD patients attending 27 Italian dialysis centres. During the 3.86%-PET we calculated the ratio of the concentrations of creatinine in dialysate/plasma (D/PCreat), the ratio between the concentrations of glucose at the end/beginning of the test (D/D0), the UF, uncorrected and corrected for bag overfill, and ΔNa.
The 3.86%-PET was repeated each year in each patient.

Results
We evaluated the results of 758 PET-3.86% in 758 incident PD patients (one test per patient) at the start of the PD therapy and then we evaluated the results of the 3.86%-PET (one test per patient and one test per year of treatment) in 382, 211 and 109 PD patients with at least two, three and four 3.86%-PET, respectively. The mean duration of PD was 5±3 months, 17±3 months, 30±3 months and 41±3 months in PD patients with at least one, two, three and four 3.86%-PET, respectively. ΔNa changed significantly after the second 3.86%-PET (8.8 ± 3.8 to 7.9 ± 4.1 mmol/L, p&lt;0.001), about after 17 months of the start of PD therapy, and its value has continued to decline significantly after 30 months (9.0 ± 3.5 to 8.3 ± 3.6 to 7.6 ± 4.1 mmol/L, p=0.001), in the cohort of PD patients with at least three 3.86%-PET, and after 41 months (9.3 ± 3.2 to 9.0 ± 3.8 to 8.2 ± 4.0 to 7.7 ± 4.0 mmol/L, p=0.02) of PD treatment, in the cohort of PD patients with at least four 3.86%-PET. D/PCreat, D/D0 and UF, uncorrected and corrected for bag overfill, changed significantly only during the fourth 3.86%-PET, about after 41 months of PD treatment.

Conclusion
The results of this study indicate that the reduction of the ΔNa is the first and an early functional alteration of the peritoneal membrane and may mean that fibrosis of the peritoneal membrane is a process that begins early after the initiation of PD. The ΔNa could be used to evaluate the effect of new solutions and/or new drugs on the functions of the peritoneal membrane since the beginning of the PD therapy.