Short peritoneal equilibration test: impact of preceding dwell time.

In the original peritoneal equilibration test (PET), which established standard values for membrane categorization in 1987, the dwell time of the preceding exchange was approximately 8 hours. Basing the test on an 8-hour prior exchange was convenient when almost all patients were on continuous ambulatory peritoneal dialysis (CAPD); however, many patients are now on some form of automated peritoneal dialysis (PD), and an 8-hour exchange before the PET requires a change in the dialysis schedule. Our goal in the present study was to determine whether the dialysate-to-plasma ratio (D/P) of solutes and the final dialysate to initial dialysate ratio (D/D0) of glucose in the short PET (2-hour equilibration time) are similar whether a 3-hour exchange or an 8-hour exchange precedes the test. The PETs were performed in 9 stable PD patients using 2 L of 2.5% dextrose dialysis solution (Baxter Healthcare, Deerfield, IL, U.S.A.). Before the equilibration exchange, the patients were on a randomly selected long (approximately 8-hour) or short (3-hour) dwell. During the equilibration exchange, dialysate samples were collected at 0.30, and 60 minutes of dwell time and from the drain bag (120-minute sample). Within a week, the PET was repeated in each patient after the alternate-length exchange. The values for D/P creatinine and urea and for D/D0 glucose were almost identical throughout the 2-hour PET after either the long or the short exchange. The D/P protein values tended to be higher in the PET after the long exchange. The short PET can be used for clinical purposes, and the creatinine and glucose results can be used for membrane categorization. Any dwell time between 3 and 12 hours is acceptable for the preceding exchange, and the equilibration test may be performed with either a 2-hour or a 4-hour dwell. The protein values obtained after a 3-hour prior dwell differ from those obtained after a long prior dwell. Protein values must therefore be standardized in a larger number of patients.