Significance of overnight D/P sodium test in continuous ambulatory peritoneal dialysis

Shin, Yong Bong; Lee, Hyun Chul; Choi, Hyok Joon; Cho, Ji Hyung; Jang, Min Hwa; Cho, Yung Jun; Park, Sun Hee; Cho, Dong Kyu; Kim, Yong Lim

Abstract

BACKGROUND: Standard PET (peritoneal equilibration test) is time consuming and it cannot reflect the water removal accurately because it measures solute transport by diffusion only. Thus, it is important to find parameters that can be used to predict both the diffusive permeability of peritoneal membrane and the peritoneal fluid removal. Sodium removal in CAPD is strongly related to the ultrafiltration and the recent study has suggested that dialysate sodium concentration at 240 minutes could reflect both peritoneal fluid removal and peritoneal transport characteristics. In this study, we investigated whether a single dialysate sodium test after overnight dwell could provide the same information as the standard PET and could reflect ultrafiltration failure.
METHODS
A 9-hour overnight dwell study with 2L of 3.86% glucose dialysis solution was carried out in 48 clinically stable CAPD patients. All patients underwent a PET test with 2L of 2.27% glucose solution in the morning after an overnight dwell study. According to ultrafiltration (UF) failure (net UF<100 mL/4 hour on 2.27% glucose solution), patients were divided into two groups (group I, UF failure group; group II, non UF failure group). D/P(Na540) and D(Na540) at the end of the 9-hour dwell were compared between two groups
RESULTS
D/P(Na540) was significantly correlated with D/Pcreatinine (r=0.551, p<0.001) and drained volume (r=-0.536, p<0.001) at 240 minutes on PET. There was also a significant correlation between D/P(Na540) and drained volume (r=-0.555, p<0.001) at 540 minutes after overnight dwell. D(Na540) was significantly correlated with D/Pcreatinine (r=0.448, p<0.01) at 240 minutes on PET and also weakly correlated with drain volume at 240 minutes (r=-0.37, p<0.01). There was a significant difference in D/P(Na540) between the group I and group II (p<0.05), but not in D(Na540).
CONCLUSION
Overnight 9-hour dwell study with 3.86% glucose solution is a simple procedure and easy to perform on outpatient basis. D/P(Na540) is comparable with PET results and may discriminate the different transport groups. D/P(Na540) may also be used as an indicator of ultrafiltration failure.