Comparison of the multiple-aliquot and batch methods of monitoring peritoneal dialysis adequacy in patients

BACKGROUND

Effluent fluid is analyzed to determine Kt/V urea and creatinine clearance as measures of adequacy of peritoneal dialysis. To avoid the physical mixing of fluids and to minimize handling of full effluent bags, a multiple-aliquot method of sampling was developed and compared to the traditional batch method.

METHODS

The batch method and the multiple-aliquot method were performed for 31 consecutive patients. Pooled fluid urea and creatinine measurements were determined for each method. PD Adequest 2.0 (Baxter Healthcare, Deerfield, IL, USA) was used to derive calculated peritoneal dialysis parameters.

RESULTS

Urea dialysate levels, calculated weekly urea clearances, protein catabolic rate, and Kt/V were not statistically different (p > 0.05) between the 2 methods. Dialysate creatinine and creatinine clearance with the 2 methods were statistically distinct but the differences were not clinically important. The processing time per set of patient effluent bags was reduced from 45 to 18 minutes, handling of the bags was minimized, and error associated with inadequate mixing of pooled fluids was avoided.

CONCLUSION

The multiple-aliquot method generates accurate and timely results to assess peritoneal dialysis prescription adequacy while reducing staff effort.

Association of Kt/V and creatinine clearance with outcomes in anuric peritoneal dialysis patients

BACKGROUND

The 2006 Kidney Disease Outcomes Quality Initiative recommended a minimum total Kt/V of 1.7, eliminated creatinine clearance (Ccr) as a target, and recommended the use of ideal body weight to calculate Kt/V. We assessed these recommendations as predictors of outcomes in anuric peritoneal dialysis patients.

STUDY DESIGN

Retrospective observational study using administrative data.

SETTING & PARTICIPANTS

1,432 peritoneal dialysis patients with anuria from January 1, 1994, to January 31, 2005, in a national sample (1,428 with Kt/V, 1,416 with Ccr).

PREDICTORS

Kt/V and Ccr at anuria; Kt/V based on actual body weight and ideal body weight.

OUTCOMES & MEASUREMENTS

Association of dialysis adequacy with mortality and time to first hospitalization after anuria assessed by using accelerated failure time models.

RESULTS

293 anuric patients had Kt/V less than 1.7, 366 had Kt/V of 1.7 to 2.0, and 769 had Kt/V greater than 2.0, using actual body weight for calculation. In unadjusted analyses, Kt/V calculated using actual body weight both less than 1.7 (-41.3%; 95% confidence interval [CI], -55.5 to -22.6) and 1.7 to 2.0 (-26.1%; 95% CI, -42.6 to -4.6) were associated with shorter time to mortality. Kt/V calculated using actual body weight less than 1.7 was associated with shorter time to hospitalization (-38.1%; 95% CI, -50.0 to -23.4), but Kt/V calculated using actual body weight of 1.7 to 2.0 was not a significant predictor (-3.3%; 95% CI, -21.1 to 18.6). After adjustment, Kt/V calculated using actual body weight less than 1.7 remained associated with mortality (-25.3%; 95% CI, -41.1 to -4.8) and hospitalization (-33.4%; 95% CI, -47.1 to -16.0). Ccr did not predict mortality. In unadjusted analysis, Ccr was not associated with hospitalization, but after adjustment, Ccr less than 50 L/wk/1.73 m(2) was significantly associated with shorter time to hospitalization (-19.9%; 95% CI, -35.0 to -1.3). Kt/V using ideal body weight was not a significant predictor in adjusted models.

LIMITATIONS

This study was nonrandomized, with few malnourished patients. In addition, there is a potential for informative censoring for transfer to hemodialysis therapy before anuria.

CONCLUSIONS

Kt/V calculated using actual body weight less than 1.7 in anuric peritoneal dialysis patients is associated with increased mortality and hospitalization. Use of ideal body weight to calculate Kt/V weakened the associations with outcomes and therefore cannot be recommended.

Report from the 1995 Core Indicators for Peritoneal Dialysis Study Group

The 1995 Peritoneal Dialysis Core Indicators Study was conducted by the Health Care Financing Administration to ascertain standard practices and outcomes in chronic peritoneal dialysis patients. Data from 1,202 patients who did not receive hemodialysis but who were on chronic ambulatory peritoneal dialysis (CAPD) for at least part of the 6-month period between November 1, 1994, and April 30, 1995, are reported. The mean serum albumin level for this cohort was 3.5 g/dL by the bromcresol green method and 3.2 g/dL by the bromcresol purple method. Data sufficient to calculate a weekly Kt/V(urea) or weekly creatinine clearance were available for only 34% of patient submissions. In these patients, the median weekly Kt/V(urea) was 1.7 using a fixed value for V of 0.58 x body weight and was 2.0 using the Watson equation to calculate V; the median weekly creatinine clearance was 60.7 L/wk/1.73 m2. The mean hematocrit for this cohort was 32% and the average weekly recombinant human erythropoietin (rHmEPO) dose was 115 u/kg. Hematocrit values < or = 30% were found in 50% of black patients and 31% of white patients. The average blood pressure among peritoneal dialysis patients was 139/80 mm Hg, with 29% of patients having a systolic blood pressure exceeding 150 mm Hg and 18% a diastolic blood pressure greater than 90 mm Hg. In summary, serum albumin levels were significantly lower in peritoneal dialysis patients than in hemodialysis patients. Approximately one third of peritoneal dialysis patients did not have an adequacy measure obtained during the 6-month observation period. A significant minority of patients had either inadequately treated anemia of chronic renal disease or hypertension. There is an opportunity to substantially improve the medical care provided to chronic peritoneal dialysis patients.