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

Enterococci are part of the normal flora of the gastrointestinal tract. They can cause enteric peritonitis, which is a serious complication of peritoneal dialysis (PD). However, the clinical course and outcome of PD-related Enterococcus peritonitis remains unclear.

We reviewed all Enterococcus peritonitis episodes occurring in our dialysis unit from 1995 to 2009.

During the study period, 1421 episodes of peritonitis were recorded. Of 29 episodes (2.0%) that were attributable to single-organism Enterococcus, 12 episodes were caused by E. faecalis; 9, by E. faecium; and the remaining 8, by other Enterococcus species. The overall rate of ampicillin resistance was 41.4%. Recent use of antibiotics was associated with the development of ampicillin-resistant Enterococcus (ARE) peritonitis (hazard ratio: 12.53; p = 0.04). The primary response rate of Enterococcus peritonitis was significantly higher than that of Escherichia coli peritonitis (89.7% vs. 69.9%, p = 0.038), but the primary response rate was not significantly lower for ARE peritonitis than for ampicillin-susceptible Enterococcus (ASE) peritonitis (83.3% vs. 94.1%, p = 0.553). However, significantly more patients with ARE had received vancomycin (83.3% vs. 23.5%, p = 0.003), with a longer mean duration of vancomycin treatment (11.8 ± 6.9 days vs. 3.7 ± 6.8 days, p = 0.005).

Recent use of antibiotics was a risk factor for the development of ARE peritonitis. Outcomes in ASE and ARE peritonitis were similar, but vancomycin was required during treatment for ARE peritonitis, in turn possibly predisposing the patients to infections caused by vancomycin-resistant organisms.

We will evaluate the effects of bioimpedance analysis–guided fluid management to reduce volume expansion, of vitamin D₃ supplementation, and of the combination of those techniques on decrease of left ventricular mass in peritoneal dialysis (PD) patients.

This multicenter randomized controlled trial, with a 2×2 factorial design, will be conducted at PD clinics affiliated with 3 Canadian teaching hospitals. Consenting PD patients 18 years of age or older will be included. Patients will be excluded if they have contraindications to bioimpedance or magnetic resonance imaging, life or technique expectancy of less than 1 year, peritonitis within the preceding 3 months, or serum calcium above 2.55 mmol/L.

The study will randomize 70 patients to bio-impedance–guided volume management or to usual care and to vitamin D₃ 50,000 U weekly for 8 doses, and then 10,000 U weekly or to matching placebo.

The primary outcome will be change in left ventricular mass at 1 year as determined by cardiac magnetic resonance imaging. The secondary outcome will be a composite endpoint of death, nonfatal cardiovascular event, and transfer to hemodialysis for dialysis inadequacy or ultrafiltration failure. Other outcome measures will include blood pressure, quality of life, 6-minute walk test, inflammatory and fibrotic markers and their association with peritoneal membrane transport properties, and residual renal function. Patients will be followed for clinical outcomes for up to 3 years.

This study will assess whether bioimpedance-directed volume management and vitamin D₃ supplementation can improve left ventricular mass in PD patients.

Recently, bimodal peritoneal dialysis (PD) solutions containing low concentrations of Na have been shown to increase 24-hour ultrafiltration (UF) or UF efficiency (UF volume per gram of carbohydrate or CHO absorbed) and Na removal in high (“fast”) transport patients during automated PD therapy. We used computer simulations to compare UF efficiency and Na removal at equivalent 24-hour UF volumes using either a generic bimodal solution (2.27% glucose + 7.5% icodextrin) during the long dwell or an increase in the glucose concentration during the short dwells, with all solutions containing Na at the conventional concentration (132 mEq/L).

The 3-pore model has been shown to accurately predict peritoneal transport for PD solutions containing glucose or icodextrin, or both. Here, we used that model to calculate 24-hour UF volume, CHO absorption, and Na removal for high (H), high-average (HA), and low-average (LA) transport patients on automated PD. Nighttime therapy consisted of 1.36% or 2.27% glucose solution (or both), and daytime therapy consisted of either Extraneal (Baxter Healthcare Corporation, Deerfield, IL, USA) or a bimodal solution.

As expected, addition of glucose to either the long dwell or the short dwells resulted in increased UF volume and glucose absorption. The increase in UF was a function of patient transport type (bimodal range: 288 – 490 mL; short-dwell range: 323 – 350 mL), and the increase in CHO absorption was smaller with glucose added to short dwells than with bimodal solution (range: 18 – 30 g vs. 34 – 39 g). The 24-hour UF efficiency was higher when high glucose concentrations were used during short-dwell exchanges than when a bimodal PD solution was used for the long dwell (0.6 to 1.2 mL/g vs. –0.1 to 0.5 mL/g). By contrast, Na removal was lower with the short-dwell exchanges (28.3 – 30.7 mmol vs. 36.2 – 53.3 mmol), likely because of more pronounced Na sieving.

Our modeling studies predict that generic bimodal PD solutions will provide higher Na removal but not higher 24-hour UF efficiency compared with current automated PD prescriptions using Extraneal for the long dwell and glucose-containing solutions for the short dwells. The modeling predictions from this study require clinical validation.

Preservation of peritoneal membrane function and residual renal function is important for the optimal care of peritoneal dialysis patients. N-Acetylcysteine may ameliorate oxidative stress, which is thought to be involved in peritoneal membrane dysfunction. In addition, N-acetylcysteine may have a positive effect on renal function in the setting of nephrotoxic contrast media administration. The aim of this study was to investigate the effect of N-acetylcysteine on peritoneal and residual renal function in peritoneal dialysis patients.

Ten prevalent peritoneal dialysis patients were administered oral N-acetylcysteine 1200 mg twice daily for 4 weeks. At baseline and at the end of treatment, peritoneal membrane function and residual renal function were assessed using a 4.25% dextrose peritoneal equilibration test and 24-hour dialysate and urine collection for calculation of peritoneal and residual renal Kt/V and mean urea and creatinine residual renal clearance.

No significant changes were demonstrated in peritoneal membrane function, including dialysate-to-plasma creatinine ratio, sodium sieving, and net ultrafiltration. Residual renal function improved significantly: urine volume increased from 633 ± 426 to 925 ± 552 mL/24 hours (p = 0.022), residual renal Kt/V increased from 0.56 ± 0.41 to 0.75 ± 0.47 (p = 0.037), and mean residual urea and creatinine clearance increased from 4.96 ± 3.96 to 5.95 ± 4.08 mL/min/1.73 m² (p = 0.059).

N-acetylcysteine may improve residual renal function in patients treated with peritoneal dialysis.

Nephrologists commonly recommend continuous ambulatory peritoneal dialysis (CAPD) with break-in periods of at least 2 weeks. We investigated the safety and feasibility of shorter break-in periods following surgical implantation of Tenckhoff catheters.

We retrospectively examined 310 patients that underwent Tenckhoff catheter implantation for the first time. The early group comprised 226 patients that started CAPD ≤ 14 days after implantation; the late group comprised 84 patients that started CAPD > 14 days after implantation. Catheter-related complications within 6 months were analyzed.

A total of 310 patients were enrolled. Time to CAPD initiation was shorter in the early group (2.0 ± 2.7 days) than in the late group (40.6 ± 42.8 days) (p < 0.001). The bridge hemodialysis rate was higher in the late group (57.1%) than in the early group (31.4%) (p < 0.001). Overall, 33 early-group (14.6%) and 11 late-group patients (13.1%) developed catheter-related complications within 6 months. The early-group complications were leakage (n = 5), diminished outflow volume (n = 7), migration (n = 7), pericatheter hernia (n = 1), hemoperitoneum (n = 1), pericatheter infection (n = 3), and peritonitis (n = 9). The late-group complications were leakage (n = 2), diminished outflow volume (n = 5), migration (n = 2), and peritonitis (n = 2). Actuarial freedom from catheter-related complications was similar in both groups (log rank, p = 0.76).

Early initiation of CAPD with surgically implanted Tenckhoff catheters is feasible and safe. Shorter break-in periods are not associated with more catheter-related complications. The data from our peritoneal dialysis population suggest that early initiation is not associated with an increased number of complications. This needs to be confirmed in a randomized trial.

Since 2000, we have used the Moncrief–Popovich technique as our standard method for peritoneal dialysis (PD) catheter insertion. The subcutaneous portion of the catheter is externalized immediately before initiation of PD. We undertook the present review to investigate whether duration of catheter embedment affects catheter or patient outcome.

All catheters inserted beginning 1 January 2000 and externalized by 31 December 2008 were included. The primary outcome was catheter survival. Secondary outcomes were catheter patency (no fibrin plug or omental wrap) and complications within 90 days after externalization. A standard peritoneal equilibration test was used to classify peritoneal membrane transport status. Proportional hazards regression models were used to test whether duration of embedment affected catheter outcomes. The models treated embedment duration as both a continuous predictor and a categorical predictor categorized by tertile.

A total of 134 catheters were implanted and externalized. Twelve patients received 2 catheters each. To ensure statistical independence of the observations, 12 of the latter 24 catheters were excluded (1 chosen randomly from each patient), resulting in a useable sample size of 122 catheters. The total duration of observation was 2359 patient–months. The median duration of catheter embedment was 40.5 days (range: 2 – 788 days). After controlling for sex, race, age, and diabetes status, embedment duration did not have a significant effect on catheter survival as a continuous predictor or as a categorical predictor. Additionally, the 95% confidence interval for the 30-day effect of embedment duration ruled out a change of more than 20.6% in the hazard of catheter malfunction or infection. Of the studied catheters, 89.3% were patent and functioned properly immediately upon externalization. The remaining 13 catheters (10.7%) lacked patency on externalization because of fibrin plug or kinking (n = 10) or omental wrap (n = 3); however, 12 of the 13 non-patent catheters were corrected laparoscopically, and the patients resumed PD. Only 1 patient transferred to hemodialysis. Overall, 121 of 122 buried catheters (99.2%) were used for PD. Other complications within 90 days of catheter externalization included incision site and tunnel infection in 2 cases (1.6%), exit-site leak in 2 cases (1.6%), and coagulase-negative staphylococcal peritonitis in 1 case (0.8%).

Duration of catheter embedment before externalization did not affect catheter survival and did not influence subsequent peritoneal membrane transport status. The overall effect of increasing embedment duration by 30 days is, at most, a 20.6% increase or decrease in the hazard of catheter failure, but the actual hazard may be much smaller or nonexistent. Larger studies are needed to further explore the ideal duration of embedment.

The use of peritoneal dialysis (PD) has been declining over the past decade in Canada, and high technique failure rates have been implicated. Studies have examined clinical risk factors for PD technique failure, but few studies have addressed sociodemographic factors driving technique failure. There are no studies examining the effect of physician factors on technique failure.

We conducted a retrospective cohort study using Ontario healthcare databases from 1 April 1995 to 31 March 2005 to examine the effects of patient sociodemographic and physician characteristics on PD technique failure. The primary outcome was time to technique failure. Secondary outcomes included the proportion of patients experiencing technique failure during the first year and the proportion of patients experiencing death during the study period. A competing risks analysis was applied to the Cox proportional hazards model to determine the predictors of technique failure, death, and kidney transplantation.

In 5162 incident PD patients, the probability of technique success and patient survival at 5 years was 58.2% and 46.9% respectively. Of patients failing PD, 43.5% failed during the first year of treatment. Statistically significant predictors of technique failure included increasing age [hazard ratio (HR) 1.02], diabetes mellitus (HR 1.32), lower neighborhood education level (HR 2.93), and receiving transient (≤ 3 months) hemodialysis before starting PD (HR 1.24). Predictors of patient death included increasing age (HR 1.05), diabetes mellitus (HR 1.44), coronary artery disease (HR 1.26), congestive heart failure (HR 1.58), and late referral to the nephrologist (HR 1.27). Distance from treating dialysis center and residing in a rural area did not impact the risk of technique failure or death. Male physician gender increased the risk of technique failure (HR 1.31). Increased PD patient volume decreased the risk of technique failure (HR 0.98). None of the physician factors were predictors of patient death.

These findings support the need for implementing strategies to reduce technique failure, which could include increasing educational resources for patients initiating PD, aggressive risk factor modification in patients with multiple comorbidities, and increasing physician awareness regarding the detrimental outcomes associated with late referral and late PD start.

While phase angle of bioimpedance analysis (BIA) has great survival-predicting value in dialysis populations, it is known to be higher in male than in female subjects. In this study, we aimed to explore the factors influencing the predictive value of phase angle and to identify the appropriate physics terms for normalizing capacitance (C) and resistance (R).

We formulated body capacitive index (BCI), C_BMI (capacitance x height²/weight), body resistive index (BRI), R_BMI (resistance x weight/height²), and CH² (capacitance x height²). We also studied H²/R, R/H, and reactance of a capacitor/height (X_C/H). There are 3 components in this study design: (1) establishment of normal values in a control Malaysian population, (2) comparison of these with a CAPD population, and (3) prediction of survival within a CAPD population. We initially performed a BIA study in 206 female and 116 male healthy volunteers, followed by a prospective study in a cohort of 128 CAPD patients [47 with diabetes mellitus (DM), 81 non-DM; 59 males, 69 females] for at least 2 years. All the parameters during enrolment, including BIA, serum albumin, peritoneal equilibrium test, age, and DM status, were analyzed. Outcome measurement was survival.

In healthy volunteers, both genders had the same BCI (2.0 nF kg/m²). On the contrary, female normal subjects had higher BRI than male normal subjects (median 15 642 vs 13242 Ω kg/m², p < 0.001) due to higher fat percentage (35.4% ± 0.4% vs 28.0% ± 0.6%, p < 0.001), resulting in a lower phase angle (mean 5.82 ± 0.04 vs 6.86 ± 0.07 degrees, p < 0.001). Logistic regression showed that BCI was the best risk indicator in 128 CAPD patients versus 322 normal subjects. In age- and body mass index (BMI)-matched head-to-head comparison, BCI had the highest χ² value (χ² = 102.63), followed by CH² (or H²/X_C; χ² = 81.00), BRI (χ² = 20.54), and X_C/H (x² = 20.48), with p value < 0.001 for these parameters. In comparison, phase angle (χ² = 11.42), R/H (χ² = 7.19), and H²/R (χ² = 5.69) had lower χ² values. 35 (27.3%) patients died during the study period. Univariate analysis adjusted for DM status and serum albumin level demonstrated that non-surviving patients had significantly higher CH² (245 vs 169 nF m², p < 0.001) and BCI (4.0 vs 2.9 nF m²/kg, p = 0.005) than patients that survived. CH² was the best predictor for all-cause mortality in Cox regression analysis, followed by BCI, phase angle, and X_C/H.

Measures that normalize, such as BCI and CH², have higher risk discrimination and survival prediction ability than measures that do not normalize, such as phase angle. Unlike phase angle, measurement of BCI overcomes the gender effect. In this study, the best risk indicator for CAPD patients versus the general population is BCI, reflecting deficit in nutritional concentration, while CH² reflects total nutritional deficit and thus is the major risk indicator for survival of CAPD patients.

Changes in essential trace elements may affect the inflammatory and immunological state of patients on hemodialysis (HD) or peritoneal dialysis (PD). Therefore, we aimed to determine trace element content and markers of oxidative stress, inflammation, and immune status in HD and PD patients and to assess the relationships among these parameters.

Patients on either HD (n = 20) or PD (n = 20) and age-, sex-, body mass index-matched healthy individuals (n = 20) were enrolled in the study. The trace elements zinc, copper, selenium, and iron; markers of oxidative stress thiobarbituric acid reactive substances (TBARS) and protein carbonyl levels; activities of antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase; percentages of CD3 T lymphocytes and the subsets CD4 and CD8; the CD4/CD8 ratio; and C-reactive protein (CRP) were measured.

All dialysis patients had low levels of albumin and hemoglobin. Significantly decreased percentages of CD3 and CD4 T lymphocytes and increased levels of CRP, TBARS, and carbonyl compounds were observed in HD patients. HD patients also had elevated erythrocyte SOD, lower GPx and catalase activities, and decreased levels of Se, Zn, and Fe in comparison to PD patients and healthy subjects. In addition, CRP was positively associated with TBARS and carbonyl levels, but was significantly inversely associated with Zn and Se levels. Positive correlations were found between T lymphocyte CD3 and CD4 percentages and Zn, Se, and Fe levels.

There were significant decreases in T lymphocyte-related immunological regulation and increased inflammation and oxidative stress in dialysis patients. Essential trace element status was independently related to immune status, inflammation, and oxidative damage.