Comparison between bicarbonate/lactate and standard lactate dialysis solution in peritoneal transport and ultrafiltration: a prospective, crossover single-dwell study.

OBJECTIVE It has been proposed that biocompatible bicarbonate/lactate based (Bic/Lac), physiologic-pH peritoneal dialysis (PD) solutions will be beneficial in long-term PD. However, we do not yet have detailed knowledge concerning the comparative physiology of buffer transport for these new solutions and their impact on underlying peritoneal transport of solutes and ultrafiltration (UF). The purpose of this study was to investigate the profile of buffer handling and peritoneal membrane transport characteristics during a single dwell of the new Bic/Lac-based versus standard lactate-based (Lac) PD solution. METHODS In this prospective crossover study, we compared a 25 mmol/L bicarbonate/15 mmol/L lactate buffered, physiologic pH, low glucose degradation product (GDP) solution (Physioneal; Baxter Healthcare, McGaw Park, Illinois, USA) with a standard lactate buffered, acidic pH, conventional solution (Dianeal; Baxter). 18 patients underwent two peritoneal equilibration tests (PETs) with 2.5% Dianeal and 2.5% Physioneal separated by 1 week. Buffer transport, mass transfer area coefficients (MTACs), solute transport, and UF were determined for the two PETs. All bags were weighed by a nurse before instillation and after drainage to assess the net UF in each dwell. RESULTS 18 patients that met the inclusion criteria were enrolled in this study. Whereas intraperitoneal pH remained constant at 7.52 +/- 0.11 throughout the dwell with the Bic/Lac solution, pH was still in the acidic range with the Lac solution after 1 hour (7.29 +/- 0.13, p < 0.001); this difference disappeared after the second hour of dwell. The MTACs for creatinine (10.68 +/- 3.66 vs 10.73 +/- 2.96 mL/minute/1.73 m(2), p > 0.05) and urea (27.94 +/- 10.50 vs 27.62 +/- 6.95 mL/min/1.73 m(2), p > 0.05), for Bic/Lac versus Lac respectively, did not differ between these two solutions; transport of glucose and other solutes was also similar. However, after a 4-hour dwell with Bic/Lac solution, net UF was significantly lower than that observed with Lac solution (274.2 +/- 223.3 mL vs 366.1 +/- 217.3 mL, p = 0.026). CONCLUSIONS Compared to standard Lac-based solution, Bic/Lac based, pH neutral, low-GDP solution avoids intraperitoneal acidity. Peritoneal mass transport kinetics are similar for small solutes. Net UF is significantly lower with Bic/Lac solution; the mechanism for this is unclear.