P1214RELATIONSHIP BETWEEN CHANGE IN DIALYSATE CONDUCTIVITY AND INTRAPERITONEAL VOLUME DURING PET

Abstract

Abstract Background and Aims Bioimpedance spectroscopy (BIS) has been widely applied to measure fluid volume in dialysis patients. A fundamentally important, yet unanswered question is how changes in fluid conductivity affects the accuracy of BIS measurements. The aim of this study was to investigate whether the change in intraperitoneal volume (IPV) is – as hypothesized - linearly correlated with the change in dialysate conductivity during a peritoneal equilibrium test (PET). Method Four PD patients (age 58±13 years, three males, weight 87.8±28 kg) were studied during a standard PET. Segmental BIS was continuously measured with eight electrodes placed between rib and buttock on both sides of the body using a Hydra 4200 (Xitron Technologies Inc ). IPV was calculated based on BIS recordings as recently published (Zhu, Kidney Blood Press Res 2019;44:1465–1475). Dialysate samples were collected hourly from baseline to the end of dwell. Dialysate conductivity was measured with a portable conductivity meter (CDH-280-KIT, Omega Engineering Inc, CT, USA). Results In all patients dialysate conductivity increased significantly (p<0.0001) from baseline (11.14±0.15 mS/cm) to the end of dwell (12.5±0.58 mS/cm) (Fig a). In 2 patients (Fig b and c) IPV and conductivity were linearly correlated; in one patient (Fig d) the relationship was nonlinear and absent in another one (Fig e). Conclusion Although the number of patients in this study was small, the results clearly indicated that dialysate conductivity increased linearly over time during PET. The correlation between dialysate conductivity and IPV is not linear and may be driven by other factors, such as dialysate electrolyte levels. In future studies measurements of dialysate electrolytes are necessary to better understand the drivers of the IPV / conductivity relationship.