Effect of increased dialysate fill volume on peritoneal fluid and solute transport

Abstract

It has recently been recommended that the peritoneal dialysate volume should in general be increased to increase the peritoneal small solute clearances. However, the net ultrafiltration volume may decrease due to higher intraperitoneal hydrostatic pressure (IPP) and higher peritoneal fluid absorption induced by higher fill volume. In the present study, we investigated the effects of increasing the fill volume on peritoneal fluid and solute transport. A four-hour dwell study with frequent dialysate and blood sampling was performed in 32 male Sprague-Dawley rats using 16 ml, 25 ml, 30 ml or 40 ml (8 rats in each group) of 3.86% glucose solution with 131I albumin as an intraperitoneal volume marker. The peritoneal transport of fluid, glucose, urea, sodium, potassium, phosphate and total protein as well as IPP with different fill volume were evaluated. The IPP and peritoneal fluid absorption rate (as estimated from the 131I albumin elimination coefficient, KE) significantly increased with increase in fill volume (P < 0.05), whereas the direct lymphatic absorption did not change with increasing fill volume. There was a strong correlation between IPP and KE. However, the net ultrafiltration volume was significantly higher in the high fill volume groups compared to the low fill volume groups, mainly due to a better maintenance of the dialysate to plasma glucose concentration gradient in the high fill volume groups. There was no significant difference in the diffusive mass transport coefficients (KBD) and sieving coefficients for any of the investigated solutes, although KBD values tended to be lower in the 16 ml group. The clearances for small solutes increased with increased fill volume, although these increases were slightly smaller than predicted from the increase in fill volume. We conclude that: (1) An increase in dialysate fill volume using 3.86% glucose solution results in higher intraperitoneal hydrostatic pressure and higher peritoneal fluid absorption, but, on the other hand, a higher net ultrafiltration; (2) The increase in net ultrafiltration with increased fill volume is mainly due to a better maintenance of glucose concentration in the dialysate, inducing an increased transcapillary ultrafiltration rate; (3) Solute clearances increase although not quite to the same extent as predicted from the increase in fill volume. Our results indicate that decreased net ultrafiltration volume associated with higher dialysate fill volume (due to higher IPP and higher peritoneal fluid absorption) could be avoided if hypertonic glucose solutions are used.

Functional and molecular characterization of a peritoneal dialysis model in the C57BL/6J mouse

“…As expected, the scaling of dialysate volume to BSA in mouse versus rat is reflected in terms of MTAC for urea, whereas D 120 /D 0 values and the UF normalized per BW are almost identical in both species (Table 3). In agreement with previous studies in man and rat [23,24], the MTAC for urea is significantly increased when using higher inflow volumes. The use of higher inflow volumes in mouse is also associated with a progressive increase in UF, reflecting higher glucose load and a better maintenance of the glucose concentration gradient (Table 2) [25].…”

Effect of Increased Dialysate Volume on Peritoneal Surface Area among Peritoneal Dialysis Patients

“…The 18% augmentation in PSA-CD after an increase in the volume of the peritoneal solution from 2 to 3 L suggests that the use of large volumes may improve the efficiency of intraperitoneal chemotherapy. The increase in peritoneal hydrostatic pressure associated with the use of largevolume solutions is a limiting factor in peritoneal dialysis, resulting in decreases in net ultrafiltration and solute removal (3,5,(32)(33)(34)(35)(36). This effect would not be a drawback for peritoneal chemotherapy, because such treatment is not aimed at removing fluid and solutes.…”

“…This suggests that an additional increase in dialysate volume might recruit a larger peritoneal surface area, resulting in a higher K BD . However, the associated increase in hydrostatic pressure in the peritoneal space would be expected to increase fluid absorption by peritoneal tissues and lymphatic vessels, thus decreasing net ultrafiltration (3,5,(32)(33)(34)(35)(36) and consequently solute removal. Nevertheless, the fact that the PSA-CD with the 3-L solution was still less than the estimated anatomic peritoneal surface area suggests that methods should be sought to provide an additional increase in PSA-CD without increasing the hydrostatic pressure inside the peritoneal cavity.…”

“…Experimental studies have demonstrated that increasing the instilled dialysate volume from 2 to 3 L results in inconsistent changes in smallsolute mass transfer area coefficients among peritoneal dialysis patients (3,4). A 250% increase in dialysate fill volume did not affect the diffusive mass transfer coefficients for urea and glucose in rats (5). The mass transfer area coefficient, or permeability-surface area product, is the solute clearance via diffusion per unit of concentration gradient (K BD ).…”

Peritoneal Dialysis in Children

“…A discrepancy between urea and creatinine PD adequacy parameters has frequently been observed in adults [174,291] and in children on APD [97], since urea clearance is more related to the dialysate volume and the number of exchanges, while CrCl is predominantly affected by the dwell time and by residual renal function. The year 2006 K/DOQI recommendations suggest the determination of dialysis and urine Kt/V urea alone for follow-up based upon the simplicity of its calculation and because studies on adult PD patients have not provided evidence of a benefit in terms of patient outcome when expressing clearance in any manner other than Kt/V urea [191,56].…”