Impact of Fill Volume on Peritoneal Clearances and Cytokine Appearance in Peritoneal Dialysis

Abstract

Background Current adequacy guidelines for peritoneal dialysis encourage the use of large fill volumes for the attainment of small solute clearance targets. These guidelines have influenced clinical practice in a significant way, and adoption of higher fill volumes has become common in North America. Several studies, however, have challenged the relevance of increasing small solute clearance; this practice may result in untoward consequences in patients. Objective The present study was designed to explore the relationship between dialysate volume and the clearance of different sized molecules, fluid dynamics, and appearance of peritoneal cytokines. Methods Thirteen adult prevalent patients on continuous ambulatory peritoneal dialysis were studied. Three different dialysate volumes (2.0, 2.5, and 3.0 L) were infused on consecutive days in a random order. Several measurements of peritoneal fluid dynamics (intraperitoneal pressure, net ultrafiltration, fluid absorption), solute clearances (urea, creatinine, β2-microglobulin, albumin, IgG, and transferrin), and appearance of interleukin-6 and tumor necrosis factor alpha (TNFα) were assessed. Results Increase in dialysate fill volume (from 2 to 2.5 to 3 L) was examined in relationship to body surface area (BSA). The dialysate volume/BSA (DV/BSA) ratio increased from 1262 to 1566 to 1871 mL/m2 on 2.0, 2.5, and 3.0 L dialysate volumes, respectively. In parallel, diastolic blood pressure increased from 82.7 ± 8.8 to 87.0 ± 9.5 to 92 ± 8.3 mmHg ( p < 0.05). Net ultrafiltration rate also increased, from 0.46 ± 0.48 to 0.72 ± 0.42 to 0.97 ± 0.49 mL/minute ( p < 0.01), despite a concomitant increase in fluid absorption, from 1.05 ± 0.34 to 1.21 ± 0.40 to 1.56 ± 0.22 mL/min ( p < 0.01). Urea peritoneal clearance increased from 8.27 ± 0.68 to 9.92 ± 1.6 to 12.98 ± 4.03 mL/min ( p < 0.01); creatinine peritoneal clearance increased from 6.69 ± 1.01 to 7.64 ± 1.12 to 8.69 ± 1.76 mL/min ( p < 0.01). Clearance of the other measured molecules did not change. Appearance of interleukin-6 increased 17% and 43% ( p < 0.01), and TNFα appearance increased 14% and 50% ( p < 0.01) when dialysate volumes of 2.5 and 3.0 L were used, compared with 2.0 L. Conclusions These results show that, with higher values of DV/BSA ratio, small solute peritoneal clearance is increased, but clearances of large molecules remain unchanged. With the use of higher volumes, fluid absorption rate and the appearance of proinflammatory cytokines in the dialysate are increased.

Increasing fill volume reduces cardiac performance in peritoneal dialysis

“…In supine position, an increase in DBP was demonstrated both with 2 l and 3 l fills compared with the drained situation. This is in accordance with Ventura et al, who demonstrated that increasing fill volume increases DBP [15]. Moreover, it has recently been shown that a fill with 3.86% glucose induces a comparable increase in blood pressure shortly after installation [2,16].…”

Tumor necrosis factor α is a risk factor for infection in peritoneal dialysis patients

“…As for the role of dialysis dose on plasma TNF-α, our data showed that plasma TNF-α inversely correlated with Kt/V, suggesting that circulating TNF-α may be removed by PD, or plasma TNF-α production may be increased with a decrease in dialysis dose. Given the previous data showing that circulating cytokines with high molecular weights higher than 15 kDa are unlikely to be removed by peritoneal clearance [ 28 ], it is more likely that the production of TNF-α (molecular weight 17 kDa) may be increased in proportion to uremic toxins in blood, resulting in the inverse relationship between plasma TNF-α levels and Kt/V.…”

In Search of a Simple and Reliable Method of Measuring Intra-abdominal Pressure in Peritoneal Dialysis Patients

“…Measuring IAP may also have other benefits in the PD patient population such as determining whether there is any impact on ultrafiltration rates, cardiac filling pressures, or feelings of fullness. 13-15 Furthermore, having an easy-to-use method to measure IAP at the bedside might allow for the use of pressure as a therapeutic guide to the PD prescription, as opposed to volume. This might have particular relevance in children.…”