Impact of peritoneal dialysis modality and acidosis on nutritional status in peritoneal dialysis patients

Continuous ambulatory (CAPD) and continuous cyclic peritoneal dialysis (CCPD) differ in solute transport, and variances in mass balance could impact nutritional parameters. Chronic acidosis may decrease albumin synthesis and increase catabolism. We prospectively studied 50 peritoneal dialysis patients (age: 55 +/- 16 yrs; CAPD = 33; CCPD = 17) over 24 months. Acidosis was defined by an anion gap > 18 mEq/L. Bioimpedance analysis was used to estimate body cell mass and fat-free mass. Patients on CAPD had a lower body mass index than CCPD patients (27 +/- 5 kg/m(2) vs. 29 +/- 9 kg/m(2) respectively, P = 0.039). However no differences were observed in body cell mass (25 +/- 8 kg vs. 26 +/- 9 kg respectively, P = 0.787) or fat-free mass (53 +/- 14 kg vs. 50 +/- 18 kg respectively; P = 0.404). Urea kinetic modeling showed no differences in Kpt/V or nPCR (0.26 +/- 0.06 vs. 0.24 +/- 0.07; P = 0.709 and 0.67 +/- 0.29 g/kg per day vs. 0.65 +/- 0.23 g/kg per day; P = 0.709 for CAPD and CCPD respectively). When categorized by the presence of acidosis no differences were observed in body cell mass (24 +/- 8 kg vs. 27 +/- 9 kg respectively, P = 0.131) or fat-free mass (54 +/- 15 kg vs. 50 +/- 16 kg respectively; P = 0.348), while body mass index was greater in acidotic than nonacidotic individuals (30 +/- 8 kg/m(2) vs. 26 +/- 6 kg/m(2) respectively; P = 0.005). Dietary protein intake assessed as nPCR was similar in both groups (0.64 +/- 0.26 vs. 0.71 +/- 0.28 g/kg per day; P = 0.319, for CAPD and CCPD respectively). We conclude that over a 24-month period neither peritoneal dialysis modality nor the presence of acidosis has a detrimental influence on nutritional parameters in well dialyzed patients.