A Simple and Fast Method to Estimate Peritoneal Membrane Transport Characteristics Using Dialysate Sodium Concentration

Abstract

Background

The peritoneal equilibration test (PET) is widely used to classify a patient's peritoneal transport characteristics. However, PET is laborious and the prediction of fluid removal based on PET is generally poor. It is believed that osmosis by glucose occurs partially through transcellular water channels, resulting in sieving of sodium and decrease of dialysate sodium concentration when using hypertonic glucose dialysate.

Objective

In this study, we investigated the possibility of using dialysate sodium concentration to classify the patient's peritoneal transport characteristics.

Methods

A 6-hour dwell study with frequent dialysate and plasma sampling was performed in 46 patients using 2 L of 3.86% glucose dialysate with 1311-albumin as an intraperitoneal volume (IPV) marker. The peritoneal transport of sodium, creatinine, glucose, and fluid was evaluated.

Results

The dialysate sodium concentration at 240 min (ONa240) significantly correlated with O/P creatinine (r = 0.76, p < 0.001) and O/O0 glucose (r = -0.83, p < 0.001) at 240 min of the dwell (better than dialysate sodium concentration at any other time of the dwell). ONa240 also significantly correlated with IPV at 240 min of the dwell (r = -0.61, p < 0.001) (better than O/P creatinine and O/O0 glucose). There were significant correlations between ONa240 and the sodium-sieving coefficient (r= 0.71, p < 0.001) and the diffusive mass transfer coefficient for sodium (r = 0.50, p < 0.001). When using ONa240 to divide the patients into four groups, as in the PET method, no significant difference was found between the two methods.

Conclusion

Using 3.86% glucose solution, ONa240 can be used instead of O/P creatinine to classify patients into different transport groups. ONa240 provides a better prediction of peritoneal fluid transport and reflects both the diffusive and convective transport properties of the membrane. As only one dialysate sample (and no blood sample) is needed, ONa240 may offer important clinical advantages compared with PET.