Long Peritoneal Dialysis Dwells With Icodextrin: Kinetics of Transperitoneal Fluid and Polyglucose Transport

Abstract

Background and objective: During peritoneal dialysis (PD), the period of effective net peritoneal ultrafiltration during long dwells can be extended by using the colloidal osmotic agent icodextrin but there are few detailed studies on ultrafiltration with icodextrin solution exceeding 12 h. We analyzed kinetics of peritoneal ultrafiltration in relation to icodextrin and its metabolites for 16-h dwells with icodextrin. Design, setting, participants, and measurements: In 20 clinically stable patients (mean age 54 years; 8 women; mean preceding time on PD 26 months), intraperitoneal dialysate volume (V_D) was estimated from dilution of ¹²⁵I-human serum albumin during 16-h dwell studies with icodextrin 7.5% solution. Sodium was measured in dialysate and plasma. In 11 patients, fractional absorption of icodextrin from dialysate, dialysate, and plasma amylase and high and low (Mw <2 kDa) Mw icodextrin fractions were analyzed. Results: Average V_D increased linearly with no difference between transport types. At 16 h, the cumulative net ultrafiltration was 729 ± 337 ml (range -18 to 1,360 ml) and negative in only one patient. Average transcapillary ultrafiltration rate was 1.40 ± 0.36 ml/min, and peritoneal fluid absorption rate was 0.68 ± 0.38 ml/min. During 16 h, 41% of the initial mass of icodextrin was absorbed. Plasma sodium decreased from 138.7 ± 2.4 to 136.5 ± 3.0 mmol/L (p < 0.05). Dialysate glucose G2-G7 oligomers increased due to increase of G2-G4 metabolites while G6-G7 metabolites and higher Mw icodextrin fractions decreased. In plasma maltose and maltotriose (G2-G3 metabolites) increased while higher Mw icodextrin oligomers were almost undetectable. Dialysate amylase increased while plasma amylase decreased. Conclusions: Icodextrin resulted in linear increase of V_D with sustained net UF lasting 16 h and with no significant difference between peritoneal transport types. In plasma, sodium and amylase declined, G2-G3 increased whereas larger icodextrin fractions were not detectable. In dialysate, icodextrin mass declined due to decrease of high Mw icodextrin fractions while low Mw metabolites, especially G2-G3, increased. The ability of icodextrin to provide sustained UF during very long dwells - which is usually not possible with glucose-based solutions - is especially important in anuric patients and in patients with fast peritoneal transport.

Keywords: amylase; end-stage kidney disease; osmotic agent; peritoneal dialysis; polyglucose metabolites; ultrafiltration.

Figure 1

Protocol of the study.

Figure 2

Intraperitoneal dialysate volume, net cumulative ultrafiltration, and dialysate and plasma sodium during 16-h dwells with icodextrin in 20 patients. (A) Individual intraperitoneal volume curves in patients previously exposed (dotted line; group ICO+; n = 3) and not previously exposed (solid line; group ICO−; n = 17) to icodextrin. (B) Intraperitoneal dialysate volume (▲; mean + SD), net cumulative ultrafiltration (•; mean − SD), and cumulative transcapillary ultrafiltration (■; mean + SD). (C) Sodium concentration in dialysate (•; mean − SD) and in plasma (■; mean + SD).

Figure 3

Net cumulative ultrafiltration and fractional absorbed amount of icodextrin during 16-h dwell with icodextrin in a subgroup of 11 patients. (A) Net cumulative ultrafiltration (mean ± SD) in subgroup of 11 patients (n = 11, ▲) including those previously exposed (group ICO+; n = 3; ■) and those not exposed (group ICO−; n = 8; •) to icodextrin. (B) Fractional (% of initial amount; mean ± SD) absorbed amount of icodextrin in subgroup of 11 patients (n = 11, ▲) including those previously exposed (group ICO+; n = 3; ■) and not previously exposed (group ICO−; n = 8, •) to icodextrin.

Figure 4

Dialysate concentrations of total icodextrin and icodextrin fractions in 11 patients. (A) Dialysate concentrations (mean ± SD) of total icodextrin and separate icodextrin fractions. (B) Dialysate concentrations (mean ± SD) of low molecular weight (LMW) icodextrin metabolites (G2–G7) and total sum of LMW icodextrin metabolites.

Figure 5

Plasma and dialysate concentrations of icodextrin metabolites G2–G3 and plasma amylase in 11 patients. (A) Plasma concentrations of icodextrin metabolites G2 (■; mean + SD) and G3 (•; mean − SD) in patients previously exposed (solid line; group ICO+; n = 3) and not previously exposed (dotted line; group ICO−; n = 8) to icodextrin. (B) Dialysate concentrations of icodextrin metabolites G2 (■; mean + SD) and G3 (•; mean − SD) in patients previously exposed (solid line; group ICO+; n = 3) and not previously exposed (dotted line; group ICO−; n = 8) to icodextrin. (C) Amylase concentration in plasma (mean ± SD) in a subgroup of 11 patients (n = 11; ▲) including those previously exposed (group ICO+; n = 3; ■) and not previously exposed (group ICO−; n = 8, •) to icodextrin during 16-h dwell with icodextrin.