Development of a Direct Peritoneal Sodium Removal Technique with Salt Free Solution

Abstract

Introduction Over time, interest in the concept of sodium and fluid removal via non-renal routes in heart failure (HF) has grown significantly. One approach to removing sodium and fluid without diuretics is peritoneal dialysis (PD). Traditional PD, however, is problematic in that it requires large intraperitoneal volumes with long dwell times while only offering limited sodium and fluid removal. Additionally, the solutions currently used in PD contain sodium concentrations that are nearly isotonic to serum, thus sodium removal is almost entirely driven by solute drag with ultrafiltration rather than diffusion down a concentration gradient. Hypothesis Utilization of salt free peritoneal solution will result in removal of a clinically significant amount of sodium and fluid. Methods Eighty kg anesthetized pigs (N=15) underwent surgical implantation of PD catheters via mini-laparotomy and venous and arterial access via cutdown. 1 liter of 10% dextrose in water was used as the sodium removal solution. In 5 pigs, we allowed a 6 hour dwell and the intraperitoneal volume was determined serially using indicator dilution technique with I-131 radiolabeled albumin (Daxor Corp., NY). 10 pigs underwent a 2 hour dwell with fluid volume measured by manual removal. To understand the effects of higher peritoneal solution volumes, 4 of these pigs then underwent 4 cycles of 2.5 L of 10% dextrose with 90 minute dwell times, for a total of 11 L cycled. These 4 animals had plasma volume measured with I-131 radiolabeled albumin (Daxor Corp., NY) prior to and after cycling was complete. Serial plasma and peritoneal fluid samples were obtained and glucose and electrolyte concentrations were determined. Results In the 5 animals with a 6 hour dwell, ultrafiltration approached 1.5 L and 5.1 +/- 0.4 grams of sodium was removed ( Fig. 1 a & 1b). In the 10 pigs that underwent a 2 hour dwell, an average of 0.9 +/- 0.2 L of ultrafiltration occurred with a corresponding 3.9 +/- 0.5 g of sodium removed ( Fig. 1 c). Despite a large sodium removal, the average decrease in serum sodium following the 2-hour dwell was only 2.2 +/- 0.3 mmol/L (P Fig. 1 d). Conclusion The direct peritoneal sodium removal approach is capable of removing large quantities of fluid and sodium with relatively small intraperitoneal volumes. Additional research is required to understand the safety/tolerability of this approach in humans, development of optimal solutions and protocols for fluid instillation and removal from the peritoneum.