Influence of different automated peritoneal dialysis schedules on solute and water removal.

patients with lower peritoneal membrane solute Introduction transport characteristics. There is yet another method, which I call a combinaAutomated peritoneal dialysis (APD) is a method tion PD because it is neither exclusively nocturnal nor where exchanges are performed mostly without active continuous. In this method, nocturnal exchanges are participation of a person but by a pre-set peritoneal followed by one or two diurnal exchanges, but the dialysis machine. APD is used in two kinds of prescripperitoneal cavity is empty for part of the day. tions: nightly peritoneal dialysis (NPD) and continuous cyclic peritoneal dialysis (CCPD) [1,2]. CCPD is a continuous, ambulatory regimen with APD growth an automated method for nightly exchanges, and a manual or assisted manual method for diurnal APD is markedly less popular than CAPD, but is the exchanges if more than one exchange is performed fastest growing home dialysis modality. Table 1 preduring the day time. NPD is a nocturnal, supine sents the number of patients on CAPD and CCPD regimen with an intermittent flow technique (NIPD) from 1990 to 1995 according to the HCFA, and the or a tidal flow technique (NTPD). For NPD, an number of patients on CAPD and APD according to alternate term—CCPD with dry days—is frequently the Baxter survey. Whereas the number of patients on used. In Health Care Financing Administration CAPD in 1995 compared with 1994 declined accord(HCFA) terminology, all methods using a cycler and ing to the HCFA and the Baxter by 10 or 12% performed at home are called CCPD. respectively, the number of patients on APD (CCPD) In an intermittent flow technique, the dialysate is dramatically increased in the same period by 44 or drained as thoroughly as possible with each exchange; 46%. (Table 1). in a tidal flow technique, after an initial fill of the The reasons for such a change in utilization of these peritoneal cavity, only a portion of dialysate is drained modalities has not been reported. In my patients, the and replaced by fresh dialysis fluid with each cycle, most common reason for switching from CAPD to leaving the majority of dialysate in constant contact CCPD is a need to increase efficiency in a way that is with the peritoneal membrane until the end of the dialysis session, when the fluid is drained as completely as possible. Table 1. Number of patients on home peritoneal dialysis modalities Although the term APD is applied to both NPD according to the HCFA and Baxter survey and CCPD, the kinetics of these methods are substantially different. Whereas CCPD kinetics are somewhat Year CAPD CCPD CAPD APD similar to those of continuous ambulatory peritoneal (HCFA) (HCFA) (Baxter) (Baxter) dialysis (CAPD), NPD kinetics and regimen are substantially different from those of CAPD; NPD is 1990 16 969 2998 17 798 3237 performed with exclusively short dwell exchanges in 1991 18 881 3797 19 628 4432 1992 20 872 4914 21 072 5650 the supine position, CCPD utilizes short and long 1993 22 573 5806 22 974 6190 dwell exchanges and at least part of the time the 1994 23 708 6931 24 176 7748 patient is ambulatory while fluid is in the peritoneal 1995 21 369 9999 21 285 11 345 cavity. NPD is best for patients with high solute transport characteristics; CCPD is preferable for HCFA=Health Care Financing Administration, Bureau of Data Management and Strategy: data from the Program Management and Medical Information System, Washington, DC end-stage renal disease program highlights distributed annually to ESRD networks. Correspondence and offprint requests to: Zbylut J. Twardowski, MD, Division of Nephrology, MA 436 Health Sciences Center, University Baxter=Baxter survey compounded annually by Baxter Healthcare, Inc., Deerfield, IL. of Missouri, Columbia, MO 65212, USA.