#2122 Dynamics of peritoneal transport and peritoneal dialysis outcomes
Authors: Salikhova Karina , Gerasimchuk Roman , Sabodash Anastasia , Zemchenkov Alexander , Vishnevskii Konstantin , Bakulina Natalia 
Published: May 2024

Abstract

Background and Aims
Volume overload is one of the most important factors associated with cardiovascular disease in peritoneal dialysis (PD) patients. On the other hand, the dynamics of peritoneal transport predicts important changes in the peritoneal membrane associated with local and systemic inflammation, which may be important for the progression of cardiovascular disease. The changes in free water transport (FWT) over time can characterize the development of peritoneal fibrosis. In a prospective study with retrospective historical control, the influence of the initial status and dynamics of peritoneal FWT on the outcomes of peritoneal dialysis, hard and surrogate cardiovascular outcomes was evaluated.

Method
According ISPD Recommendations (2021) the function of peritoneal membrane solute transfer was evaluated in classical PET in the exchange of 2 liters of 2.5% glucose solution with the calculation of the creatinine D/P4 ratio, which was used in the analysis as a continuous value (peritoneal solute transfer rate - PSTR), as well as categorized into high, medium-high, medium-low and low (H, HA, LA, L, respectively) levels of peritoneal transport. The mass transfer coefficient (MTAC) was also calculated.
The ultrafiltration function of the membrane and its dynamics were evaluated by measuring the transport of water through small pores and free water through ultrapores, in double mini-PET (in two one-hour exchanges with solutions of 4.25% and 1.5% glucose). FWT is the calculated value; the primary measured value is the degree of reduction of sodium in the dialysis solution one hour after the start of the exchange (dipNa) formed as a result of electrolyte-free water transport through ultrapores (aquaporins), which dilutes dialysate.

Results
Table 1 shows the average values of peritoneal transport indicators at the beginning of follow-up and the annual changes calculated over the entire period of prospective follow-up for each patient.
Major adverse cardiovascular events (Table 2) were recorded with a relatively low frequency, but significantly differed by incidence between the subgroups with high (H) and high-average (HA) peritoneal transport, on the one hand, and low-average (LA) and low(L), on the other: 0.626 ± 0.049 vs. 0.320 ± 0.042 events per year; p&lt;0.001, (49% fewer events). Similarly, there was a significant difference in the MACE incidence between patients with slow and rapid decrease in free water transport (divided by the median of the rate of in free water transport decrease): 0.414 ± 0.044 vs. 0.510 ± 0.051 events per year; p &lt; 0.001, (19% fewer events). The same calculations for nonfatal cardiovascular events showed a fewer incidence of 47.2% and 17.1%, respectively. Thus, patients with a high transport status (according to the PET test) and patients with a rapid decrease in water transport through aquaporins (indicating an increase in fibrotic changes in the peritoneal mesothelium), accompanied also by an increase in peritoneal permeability to solutes, including glucose, are at greater risk of progression of cardiovascular disease.

Conclusion
In addition to confirming the link between the initial status of peritoneal transport and the subsequent incidence of cardiovascular events, it would be interesting to confirm the influence of cardiovascular disease (as a proinflammatory condition and as a factor of volume overload, forcing the wider use of concentrated solutions which damage the peritoneum) on the progression of peritoneal fibrosis, but according to available materials it was not possible due to the limited number of patients in the study (especially – patients with repeated assessments of peritoneal transport after the cardiovascular events) and low frequency of peritoneal transport monitoring, on the one hand, and uncertainty in identifying the exact time of development of heart failure and the need for revascularization. Continued prospective observation would clarify these links.