Sodium removal by peritoneal dialysis: a systematic review and meta-analysis

Abstract

Achievement of sodium and fluid balance is considered a major determinant of dialysis adequacy in peritoneal dialysis (PD). However, the contribution of different PD modalities to dialytic sodium removal (DSR) remains ill-defined. We performed a systematic review and meta-analysis to compare DSR by manual (continuous ambulatory PD, CAPD) versus automated PD (APD). Alternative PD strategies to remove sodium were also analyzed. Seven cohort studies, including 683 patients, 406 in CAPD and 277 in APD, were meta-analyzed out of the 30 studies selected based on DSR data availability. Overall, the unstandardized mean difference between CAPD and APD was significant [- 56 mmol/day (95% CI - 106, - 6), p = 0.027]. Heterogeneity was high (I 87.2%; p < 0.001). Meta-regression showed a strict correlation of DSR difference with creatinine dialysate/plasma ratio (D/P) (p = 0.04). DSR was significantly lower in APD than CAPD [86.2 (57.3-115.1) vs. 141.3 (107.6-174.9) mmol/day, p = 0.015]. Conversely, ultrafiltration (UF) did not differ [1122.6 (891.2-1354.0) in CAPD and 893.6 (823.0-964.2) ml/day in APD, p = 0.064]. A very strong correlation between DSR and achieved UF was found in CAPD (R = 0.94; p < 0001) while no relationship was detected in APD (R = - 0.07; p = 0.85). CAPD allows a higher DSR than APD, even though UF is not different. APD removes more water than sodium; therefore, DSR should be measured rather than estimated from the achieved UF. The difference in DSR between the two modalities decreases in high transporters. Novel strategies proposed to increase DSR, e.g. lower sodium dialysate or adapted-APD, are promising, but ad hoc studies are necessary.

Optimized vs. Standard Automated Peritoneal Dialysis Regimens (OptiStAR): study protocol for a randomized controlled crossover trial

“…While we expect no difference in sodium removal between the regimens, we do however expect a lower sodium removal in APD with respect to CAPD, mainly due to the shorter dwell times involved. Indeed, a recent meta-analysis including 683 patients showed that CAPD offers a higher sodium removal than APD even though UF is not different [8].…”

Sodium Intake and Chronic Kidney Disease

“…Therefore, salt restriction remains the basic approach to achieve volume control in PD patients, keeping in mind that sodium removal is lower in PD patients treated with cycler (Automated PD, APD), because of greater sodium sieving as compared with Continuous Ambulatory PD (CAPD). In these patients, high salt intake may not be counterbalanced by sodium removal, consequently leading to hypervolemia and hypertension [88].…”

Customization of Peritoneal Dialysis in Cardiorenal Syndrome by Optimization of Sodium Extraction

“…The results of this study can be in part explained by the fact that almost 80% of the APD patients received icodextrin for their long daytime dwell, and the number of nocturnal exchanges were reduced (i.e., allowing for longer dwells and less sodium sieving). Nevertheless, a recent meta-analysis including 683 patients from 7 studies concluded that CAPD is associated with significantly higher SR compared with APD (141 vs. 86 mmol/day, respectively, p = 0.015) [20]. Since APD is the predominant modality in many countries, a number of investigators have explored methods (i.e., tidal APD and mid-day exchange) to enhance its SR capability rather than switching to CAPD.…”

“…The correlation between ultrafiltration volume and sodium extraction could be more pronounced in patients treated with CAPD than APD (possibly due to a higher proportion of the ultrafiltrate volume being from the sodium-free water in APD) [20]. …”