Clinical evaluation of the peritoneal equilibration test: a population-based study.

A total of 143 Peritoneal Equilibration Tests (PETs) were performed in 104 CAPD patients over a period of 18 months. A normal range (95% confidence limits) was constructed from 100 tests (68 consecutive new patients, 32 routine tests on problem-free patients) using a 2-dimensional plot of solute transfer (D/Pcreat) and ultrafiltration volume. These two parameters correlated inversely (r = -0.59, P < 0.0001) allowing calculation of a regression line. In the short term (< 3 months) D/Pcreat was stable across a wide range of values (0.45-0.98) with good correlation between tests indicating reproducibility (r = 0.94, P < 0.001). Repeated tests beyond 3 months were variable, explaining changes in the clinical picture, and in the majority of cases shifts in D/Pcreat and ultrafiltration parallelled the regression line for the whole population. Six of seven (85%) of patients with mechanical problems and 14 of 15 (93%) with poor ultrafiltration had at least one abnormal test, and these two problems could be distinguished in 90% of cases by 2-dimensional plotting. In five with ultrafiltration failure, dialysate volumes were less than predicted by solute clearance, and these patients failed continuous cycling peritoneal dialysis (CCPD). In contrast, a good response to CCPD was predicted correctly in five patients with high solute clearance. In nine patients with plasma creatinine > 1250 mumol/l the PET was normal. The PET is a useful adjunct to understanding and prescribing peritoneal dialysis, particularly when repeated tests are compared to a well-defined normal population.