Influence of the preceding exchange on peritoneal equilibration test results: a prospective study

The standard peritoneal equilibration test (PET) should be performed after a long overnight dwell, which is easily possible in continuous ambulatory peritoneal dialysis patients. However, for such a procedure, patients undergoing automated peritoneal dialysis or daily ambulatory peritoneal dialysis have to change their regimen and, in the case of high peritoneal transport rates, run the risk for fluid absorption. We compared dialysate to plasma ratios (D/P) of creatinine, blood urea nitrogen (BUN), phosphate, sodium, total protein, and albumin measured during PET after an 8- to 11-hour dry period (PET dry), after a preceding exchange with a long dwell time (PET standard), and immediately after tidal peritoneal dialysis (PET tidal). D/P ratios of creatinine, BUN, phosphate, and sodium at 2 and 4 hours were greater during PET dry compared with both PET standard and PET tidal. The quotient of dialysate glucose at 2 hours to dialysate glucose at time point 0 was significantly less in PET dry compared with both PET tidal and PET standard. During the first 2 hours of PET, the increase of D/P curves of creatinine and BUN, as well as phosphate, was significantly steeper in PET dry than PET tidal and PET standard. D/P ratios of albumin and protein were greatest in PET dry and least in PET tidal. There was a significant difference between all three PETs at 0, 2, and 4 hours of dwell time. PET curves were significantly steeper during PET dry compared with PET tidal in case of D/P protein (during the first 2 hours of dwell time) and D/P albumin (during the entire dwell time). Similar differences between the PET curves of protein and albumin were observed between PET dry and PET standard. These data clearly indicate a dry period before PET significantly influences the D/P ratios of small solutes, protein, and albumin measured during the test.