DRAIN VOLUME REQUIRED FOR A TARGET PERITONEAL CLEARANCE - FORMULAS BASED ON PERITONEAL TRANSPORT TYPE AND BODY-SIZE

The authors developed formulae calculating the daily drain volume (DV) required for a target normalized peritoneal clearance of urea (Kt/V-u r) or creatinine (C-cr, Kt/V-cr) in peritoneal dialysis (PD). DV depen ds on the target clearance, the peritoneal solute transport type, and the size of the person as expressed by body surface area (BSA) or body water (V) To illustrate the formulae, we constructed nomograms for th e following weekly target clearances: C-cr = 60 L/1.73 m(2), Kt/V-ur = 2.0, Kt/V-cr = 1.8 (the value corresponding to a C-cr of 60 L/1.73 m( 2) in a linear regression of the two parameters in 476 clearance studi es in continuous ambulatory PD [CAPD] patients). The PD schedules stud ied included CAPD, continuous cycling PD (CCPD) with one 2 L daytime d well, and a combination of daytime CAPD and night-time automated PD (A PD) with 2 hr dwell times. Peritoneal transport was characterized as l ow, low-average, high-average, or high by the dialysate-to-plasma (D/P ) creatinine concentration ratio in a peritoneal equilibration test (P ET). The D/P value entered for each transport type was the appropriate 95% lower confidence limit of the mean D/P in actual studies (2 hr an d 4 hr D/P from 102 PET studies and 5.5 hr D/P from 476 clearance stud ies in CAPD patients). For high transport, the required DV values were similar in all three PD schedules studied. For low transport, the req uired DV was much larger, comparatively, for CCPD and CAPD-APD than fo r CAPD. Furthermore, the DV values required for a weekly Kt/V-ur of 2. 0 were comparatively less than the DV values required for a weekly Kt/ V-cr of 1.8 (C-cr of 60 L/1.73 M-2). Calculation of the DV required fo r different PD schedules, a target peritoneal clearance, and the patie nts's size is feasible when the patient's peritoneal transport charact eristics are known. This calculation also allows the selection of the least costly PD schedule. Current target values for urea and creatinin e clearance are incompatible in anuric PD patients.