Peritoneal Dialysis International: Journal of the International Society for Peritoneal Dialysis

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.

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.

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 m², p > 0.05) and urea (27.94 ± 10.50 vs 27.62 ± 6.95 mL/min/1.73 m², 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).

Compared to standard Lac-based solution, Bic/Lac based, pH neutral, low-GDP solution avoids intra-peritoneal 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.

This study was designed to compare the local peritoneal and systemic inflammatory effects of a conventional lactate-based (Lac) peritoneal dialysis (PD) solution and a new biocompatible bicarbonate/lactate-based (Bic/ Lac) solution having low concentration of glucose degradation products.

26 stable, prevalent PD patients were enrolled in this prospective study. They sequentially underwent 3 months of therapy with the Lac solution and 3 months with the Bic/Lac solution in a randomized order. Flow cytometry was used to measure the expression of inflammatory molecules on peritoneal cells in overnight effluent collected at the end of each study period.

21 patients successfully completed the study. Mean fluorescence intensity of human leukocyte antigen (HLA)-DR and CD14 expression by macrophages were not different between Lac and Bic/Lac. The peritoneal appearance rate of cancer antigen 125 (kU/minute) was 68 ± 37 with Lac and 133 ± 66 with Bic/Lac (p < 0.001), and of interleukin (IL)-6 (ng/minute), 0.28 ± 0.2 with Lac and 0.18 ± 0.16 with Bic/Lac (p = 0.014). HLA-DR macrophage expression and IL-6 peritoneal appearance rates did not correlate. Serum concentrations with Lac and Bic/Lac were, for IL-6, 3.49 ± 2.28 and 3.72 ± 2.46 ng/L (p = 0.17), and for high-sensitivity C-reactive protein, 2.31 ± 2.98 and 2.71 ± 3.31 mg/L (p = 0.32) respectively. The concentration of effluent macrophages (x10⁶/L) with Lac was 1.6 ± 1.6 and with Bic/Lac 2.6 ± 3.3 (p = 0.07).

We conclude that, although there was a significant reduction in peritoneal IL-6 in patients using Bic/ Lac solution, systemic levels of inflammatory markers did not differ between the two solutions and no changes were present in macrophage surface activation markers, suggesting perhaps a less important role of peritoneal macrophages in the intraperitoneal chronic inflammatory process. The number of effluent macrophages tended to be higher in patients using the Bic/Lac solution, possibly contributing to improved intraperitoneal defense.

The three-pore model of peritoneal transport is used extensively for modeling peritoneal fluid and solute transport, but the currently used versions include certain modifications of the transport parameters that have not been validated quantitatively versus detailed data on fluid and solute kinetics. The aim of this study was to evaluate different versions of the three-pore model.

Detailed clinical peritoneal fluid and solute transport data were obtained from 40 peritoneal dwell studies in clinically stable continuous ambulatory peritoneal dialysis patients in whom the dialysate volume was measured using a macromolecular volume marker (RISA).

Using a new version of the three-pore model with several adjusted transport parameters, good agreement between the measured and the simulated values of dialysate volume and concentrations of small solutes and RISA (but not of endogenous protein) versus dwell time was obtained; however, the predicted peritoneal absorption for longer than the investigated dwell time would be too high.

The three-pore model, with some adjustments proposed in this study, may be used for detailed description of peritoneal transport kinetics, but it should be pointed out that, even after these adjustments, it still does not provide the correct description of peritoneal fluid absorption and transport of macromolecules.

Since the introduction of surgical debulking in combination with intraoperative hyperthermic intra-peritoneal chemoperfusion (HIPEC) with oxaliplatin in our institution, severe hyponatremia (sodium: 126.5 ± 3.8 mmol/L), hyperglycemia (glucose: 22.37 ± 4.89 mmol/L), and hyperlactatemia (lactate: 3.17 ± 1.8 mmol/L) have been observed post HIPEC. This metabolic disorder was not observed in patients in whom cisplatin or mitomycin C was used as a chemotherapeutic drug.

In order to understand the pathophysiology of this finding, an analysis of our data was made. In a first analysis, plasma sodium was corrected for hyperglycemia based on the formula of Hillier. In a second analysis, the influence of total exchangeable sodium, total exchangeable potassium, and total body water on plasma sodium concentration was modeled.

Analysis of our data revealed a double mechanism for the observed metabolic disorder: hyperglycemia caused by dextrose 5%, which is used as a carrier for the oxaliplatin, and major loss of sodium into the dialysate (256.7 ± 68.7 mmol).

Better control of hyperglycemia and intravenous compensation of sodium loss into the dialysate can attenuate the reported biochemical disturbance.

Peritonitis remains the most serious complication of peritoneal dialysis (PD). Gram-positive organisms are among the most common causes of PD peritonitis; however, recent trends show increasing rates of gram-negative and fungal infections. Strategies to prevent peritonitis include the use of prophylactic topical mupirocin at the site where the PD catheter exits from the abdominal wall; however, mupirocin does not afford protection against gram-negative or fungal infections. The aim of this study is to determine if the incidence of catheter-related infections (exit-site infection, tunnel infection, or peritonitis) is significantly reduced by the routine application of Polysporin Triple antibiotic ointment (Pfizer Canada, Markham, Ontario, Canada) in comparison to mupirocin ointment.

The Mupirocin Versus Polysporin Triple Study (MP3) is a multicenter, randomized, double-blinded controlled study comparing Polysporin Triple (P3) against the current standard of care. The aim of the study is to recruit 200 patients being treated with or starting on PD and randomize them to receive either mupirocin or P3 at the catheter exit site. Patients will be followed for 18 months or until death or transfer from PD to an alternate treatment modality. The primary outcome will be the time to first catheter-related infection. Catheter-related infections will be strictly defined using current guidelines and categorized into exit-site infections, infective peritonitis, or tunnel infections. The primary analysis will be an intention-to-treat analysis.

The results of this study will help determine if the use of P3 is superior to mupirocin ointment in the prevention of catheter-related infections and will help guide evidence-based best practices.

Predialysis nephrology care is thought to affect morbidity and mortality in hemodialysis patients. This study evaluated the impact of different patterns of predialysis care on outcomes of patients undergoing chronic peritoneal dialysis (PD).

Retrospective cohort.

275 patients enrolled from January 1997 to March 2005 in a medical center in North Taiwan who recently initiated dialysis were classified according to early or late referral to nephrologists (≥ 6 or <6 months of dialysis), planned or late implantation of Tenckhoff catheters (absence or presence of preceding emergent hemodialysis), and early or late start of dialysis [glomerular filtration rate (GFR) ≥ 5 or <5 mL/minute/1.73 m²].

All-cause mortality and hospitalization.

During a median follow-up of 2.5 years, 41 deaths, 38 transfers to hemodialysis, and 26 renal transplantations occurred. Late start of dialysis was associated with a significant survival benefit (log rank, p = 0.012) and, along with planned implantation of catheters, exhibited a reduced risk for all-cause hospitalization (log rank, p = 0.025, 0.013). The predictors of overall mortality included baseline GFR [hazard ratio (HR) 1.18, p = 0.023], age (HR 1.07, p < 0.001), and diabetes (HR 3.64, p = 0.001); whereas the risk factors for all-cause hospitalization included age (HR 1.02, p = 0.012), late implantation of catheters (HR 1.78, p = 0.011), and diabetes (HR 1.92, p = 0.005). The timing of nephrology referral did not affect either death or hospitalization.

Our data do not support earlier initiation of PD, but underscore the importance of planned implantation of catheters before commencement of chronic PD.

Patients on continuous ambulatory peritoneal dialysis (CAPD) who have high small-molecule peritoneal transport have increased mortality.

To investigate the impact of baseline peritoneal transport characteristics on patient and technique survival in incident peritoneal dialysis (PD) patients, most of whom are on automated PD (APD), with the use of icodextrin.

Retrospective observational cohort study.

A single PD unit.

193 new patients that began PD between January 2000 and September 2004, and had an initial peritoneal equilibration test within 6 months of commencement of PD. Patients were divided into low (L), low average (LA), high average (HA), and high (H) peritoneal transport groups. Death-censored technique failure and patient survival were examined.

Of the 193 patients, 151 (78.1%) were on APD or on APD with icodextrin or on CAPD with icodextrin. At the end of 1, 3, and 5 years, patient survival was 91%, 82%, and 67% in LA group; 95%, 77%, and 69% in HA group; and 96%, 71%, and 71% in H group. Technique survival was 100%, 90%, and 77% in LA group; 96%, 84%, and 72% in HA group; and 92%, 87%, and 77% in H group. High peritoneal permeability did not predict worse patient survival or technique failure, while age, diabetes, a lower glomerular filtration rate, and high body mass index (≥ 30 kg/m²) were independent predictors of death.

This study suggests that higher peritoneal transport is not a significant independent risk factor for either mortality or death-censored technique failure. The favorable outcome for high transporters in this study may be due to improved management of volume status by the increased use of APD and the use of icodextrin-based dialysis fluid.