Table V summarizes the prognostic usefulness of the baseline peritoneal equilibration test. The patients with high peritoneal transport are ideal candidates for regimens with short dwell exchanges (NIPD, NTPD, DAPD)I. The patients with high average transport are excellent candidates for any peritoneal dialysis prescription. Most patients with low average peritoneal transport can be maintained on the standard dose CAPD; however, many of them may require a modified prescription (high dose CAPD, high dose CCPD) when residual renal function becomes negligible, particularly if they have high body surface area. These patients have excellent ultrafiltration with moderate dialysis solution glucose concentrations. Finally, patients with low peritoneal transport rates usually have excellent utltrafiltration with low dialysis solution glucose concentration and are very likely to develop symptoms of inadequate dialysis on standard CAPD when their residual renal function becomes negligible. These patients are not good candidates for regimens with short dwell exchanges.
PET versus clearances for determining peritoneal dialysis prescriptions
The PET is a simple and only approximate measure of peritoneal dialysis performance. It cannot completely replace clearance measurements but it is a useful guide in choosing dialysis prescription in the majority of patients. On the other hand clearance alone is insufficient as a guide for choosing regimen and technique (intermittent vs continuous, short vs long dwell exchanges) .Moreover, PET is very useful in diagnosing the cause of insufficient dialysis or ultrafiltration (9). The PET and clearance measurements are complementary studies which can guide in dialysis prescription.
Stepwise approach to PD prescriptionFigure 3 presents stepwise approach to peritoneal dialysis prescription. Usually I start with a standard schedule of four 2 L exchanges in most patients. In patients with well preserved residual renal function (endogenous creatinine clearance >5.0 ml/min) the total dialysis solution inflow is decreased to below 7.5 L per day. The peritoneal equilibration test is performed in all patients and serves as a prognosticator of a patient's response to various peritoneal dialysis regimens.
The patient is followed closely and the prescription is modified to preferred when the residual renal function becomes negligible and/ or criteria of adequate dialysis are not fulfilled. If preferred prescription does not deliver adequate dialysis, daily creatinine clearance is measured and the prescription modified as needed. If dialysis is inadequate by clinical and laboratory criteria despite creatinine clearance over 40 L/week/ 1.73 m2 BSA, a higher dose of dialysis is recommended.
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- TwardowskiZJ. The Fast-PET. Seminars in Dialysis. 1990; 3: (In press). 1 See page 47 for Peritoneal Dialysis Glossary.
Zbylut J. Twardowski M.D. , Division of Nephrology, MA 436 Health Sciences Center, University of Missouri, Columbia, MO 65212, U.S.A.