Re-evaluation of solute transport groups using the peritoneal equilibration test.

OBJECTIVE: To determine if the previously described peritoneal equilibration test (PET)-determined solute transport groups, as defined by Twardowski, fit our patient population. DESIGN: We reviewed the 195 initial standardized PETs (on 195 patients) performed through our peritoneal dialysis program since 1989. Using the method originally defined by Twardowski using the means and standard deviations of the PET-determined dialysis/plasma ratio (D/P) of creatinine and dialysate-to-0 hour dialysate (D/D0) glucose values, transport groupings for our patient population were determined. Comparisons were then made between patient populations. RESULTS: The mean 4-hour D/P creatinine in our patients was 0.70 +/- 0.10. This compares to a mean of 0.65 +/- 0.15 as determined by Twardowski, and indicates that our patients have higher mean solute transport characteristics and tighter ranges within transport groups than previously reported. Only 2% of our patients fell into the previously described low (L) range, with 30% low average (LA), 51% high average (HA), and 17% high (H). Using our data, we would redefine the groups by a 4-hour D/P creatinine as L < 0.60, LA = 0.60-0.70, HA = 0.70-0.80, and HA > 0.80. Using these values, our population fits a Gaussian distribution with 17% L, 31% LA, 33% HA, and 19% H. CONCLUSION: Our patients have higher mean solute transport and tighter ranges within transport groups than previously reported. Using the previously defined PET-determined transport groupings, low transporters are particularly underestimated. If our population data are representative of the peritoneal dialysis population as a whole, these ranges should be redefined.

Reproducibility of studies of peritoneal dialysis adequacy.

To assess the variability and reproducibility of dialysis adequacy clearance measurements (weekly Kt/V and weekly creatinine clearance/1.73 m2 BSA) in a given patient, 42 patients underwent three clearance studies in a one week period. The dialysis prescription was kept constant. There were 21 males with a group mean age of 49 +/- 15 years; 37 patients performed CAPD and 5 DAPD; the dialysis prescription was 6 to 12 liters/day; and 17 patients were anuric. To assess test variability within each patient, the coefficient of variation (CV) and the range were determined for each patient's three clearance values, and for the factors that determine those values. These were averaged to determine the mean patient variability (CV and range) of those measurements. The mean patient CV of the weekly Kt/V was 8.1%. The mean patient range of the weekly Kt/V was 0.30. Of the determinants of total Kt/V, the greatest variability (GV) existed in residual renal urea clearance at 35.4%, with moderate variability seen for peritoneal dialysis urea clearance at 7.0%, which was more a function of variability in D/P urea (CV = 6.3%) than variability in drain volume (CV = 4.1%). There was little variability in V (CV = 0.6%). Similar results were seen for the variability in weekly creatinine clearance measurements. We found that the day-to-day reproducibility of Kt/V measurements is limited, especially in patients with residual renal function, although day-to-day variability in D/P urea also affects Kt/V reproducibility in all patients. Values that fall into the borderline "adequate" range may need to be repeated when considering a patient's dialysis prescription. In addition, research that involves the measurement of Kt/V should utilize more than one collection to increase the reliability of those measurements.

Peritonitis in an urban peritoneal dialysis program: an analysis of infecting pathogens.

We have previously found that race, level of education, and peritoneal dialysis system are factors that significantly and independently influence peritonitis rates in our patient population. We now extend these observations by assessing the pathogens responsible for peritonitis in these subgroups. Between January 1, 1981, and May 15, 1993, 248 peritoneal dialysis patients underwent dialysis at our facility. The rate of peritonitis by pathogen was determined in these patients using the fixed effects Poisson model. Total peritonitis rates in black patients (1.89 episodes/patient-year) were significantly greater compared with white patients (1.11 episodes/patient-year; P < 0.0001). Increased infection rates in black patients were significant for Staphylococcus epidermidis, Staphylococcus aureus, and gram-negative pathogens. The level of education had a negative correlation with peritonitis rates (< or = 8 years, 2.00 episodes/patient-year; 9 to 12 years, 1.64 episodes/patient-year; and > or = 13 years, 1.24 episodes/patient-year) with patients having > or = 13 years of education at the start of dialysis demonstrating a significantly lower total peritonitis rate compared with patients with 9 to 12 years (P = 0.001) or < or = 8 years (P < 0.001) of education. This was accounted for by a significant decrease in infection rates for S epidermidis, polymicrobial, and gram-negative organisms. Finally, patients on automated peritoneal dialysis had significantly lower total peritonitis rates (0.59 episodes/patient-year) compared with patients on either a connect (2.11 episodes/patient-year) or disconnect (1.46 episodes/patient-year) system.(ABSTRACT TRUNCATED AT 250 WORDS)

Advanced glycosylation end products in continuous ambulatory peritoneal dialysis patients.

Low molecular weight advanced glycosylation end products (AGEs) were evaluated for by an enzyme-linked immunosorbent assay in 30 patients on continuous ambulatory peritoneal dialysis (29 patients) and continuous cyclic peritoneal dialysis (one patient). Thirteen patients were diabetic and 17 patients were nondiabetic. All patients underwent peritoneal equilibration tests and, in addition to routine chemistries, serum and dialysate were evaluated for AGEs. Serum creatinine levels were similar in the diabetic and nondiabetic patients, but serum AGE levels were significantly higher in the diabetic patients (16.2 +/- 5.3 v 8.2 +/- 2.3 U/mL; P < 0.0001). Overall, the dialysate to plasma ratio at 4 hours was 0.69 +/- 0.08 for creatinine and 0.18 +/- 0.06 for AGEs. The mass transfer area coefficient for all patients was 12.4 +/- 3.12 mL/min for creatinine and 2.03 +/- 0.93 mL/min for AGEs. The peritoneal transport of AGEs as measured by dialysate to plasma ratios at 4 hours and by mass transfer area coefficients was significantly less (P < 0.001) than that for creatinine. No significant difference in dialysate to plasma ratios or mass transfer area coefficient for creatinine or AGEs was noted between diabetic and nondiabetic patients. The peritoneal transport of AGEs is poor and leads to elevated serum levels, especially in patients with diabetes mellitus. The accumulation of AGEs may contribute to the increased cardiovascular mortality seen in patients with end stage renal disease. This is most marked in patients with diabetes mellitus.

A retrospective assessment of risk factors for peritonitis among an urban CAPD population.

Peritonitis is a major reason why patients transfer from peritoneal dialysis (PD) to hemodialysis. We evaluated the peritonitis infection rates in 146 peritoneal dialysis patients who underwent dialysis at our facility between 1 January 1981 and 31 December 1989. Peritonitis was the primary cause for changing treatment, with 24 (16.4%) of the patients transferring because of this complication. This represented 54.5% of all patients discontinuing CAPD due to method failure. A gamma-Poisson regression analysis was performed in an attempt to identify potential risk factors associated with an increased incidence of peritonitis. The results indicated that race, education level, and PD system used were significantly associated with the rate at which peritonitis occurred in our patient population. There was an almost twofold increase in the rate of peritonitis among blacks as compared to whites (2.2 vs 1.2 episodes/patient year). The level of education completed at the start of dialysis had a negative correlation with peritonitis rates. Patients with < or = 8, 9-12, and > or = 13 years of education had peritonitis rates of 2.4, 1.8, and 1.2 episodes/patient year, respectively. Finally, the system used had a significant effect with our patients on CCPD having lower peritonitis rates as compared to patients on either a connect or disconnect system (0.6 vs 2.5 vs 1.8 episodes/patient year, respectively). Recognizing potential risk factors for peritonitis will help us better understand and address this significant problem in our PD programs. Reducing peritonitis rates should facilitate a decrease in patient transfer due to method failure.

The effect of hematocrit on peritoneal transport.

Eight stable patients, from our institution, on continuous ambulatory peritoneal dialysis (CAPD) were entered into a multicenter, randomized, double-blind, placebo-controlled study with erythropoietin (EP]. To assess the effect of hematocrit on peritoneal solute transport, we performed peritoneal equilibration tests (PET) on each patient on a quarterly basis throughout the study. Patients on EPO had a significant increase in hematocrit at 3 (32% +/- 5%), 6 (32% +/- 2%), and 9 (38% +/- 3%) months compared with baseline (22% +/- 4%). The D/P creatinine (Cr) at 4 hours was also significantly reduced in the patients on EPO at 3 (.70 +/- .1), 6 (.66 +/- .12) months when compared with baseline (.76 +/- .11). No significant change in D/Do glucose at 4 hours or in the 4-hour ultrafiltrate (except at 9 months) was found. Based on mixed-effects regression analysis, the 4-hour D/P Cr, peritoneal Cr clearance, and Cr mass transfer area coefficient significantly decreased as hematocrit levels increased. The 4-hour D/Do glucose and the 4-hour ultrafiltrate both demonstrated a positive correlation with increasing hematocrit levels, but this did not reach statistical significance. Although larger studies are needed, it appears that increasing hematocrit levels may negatively affect peritoneal solute transport in CAPD patients as determined by PET.

Patient and technique survival among an urban population of peritoneal dialysis patients: an 8-year experience.

Estimates of patient and technique survival are given for 146 peritoneal dialysis (PD) patients who underwent dialysis between January 1, 1981 through December 31, 1989. In all, 33 patients died and 44 patients changed treatment. Patient survival was 92% at 1 year, 80% at 2 years, and 55% at 4 years, while technique survival was 85% at 1 year, 74% at 2 years, and 47% at 4 years. Cox's proportional hazards regression model was used to assess the effects of sex, age, diabetes, cardiovascular disease (CVD), education, and training time on both patient and technique survival. Both patient age (P = 0.001) and CVD (P = 0.03) had a significant impact on patient survival. On the average, for every 10 years' increase in age, the risk of death increased by a factor of 1.71. Patients with CVD had a risk of death 2.57 times higher than the risk of death among patients without CVD. With respect to technique or method survival, black patients had a risk of changing treatment 2.24 times higher than that for white patients. Our patient and technique survivals are similar to that reported in the national CAPD registry over a comparable period (1981 to 1988).