ADEQUACY OF CAPD - A COMPARISON WITH OTHER DIALYSIS MODALITIES

93 dialysis patients were included in a prospective trial on treatment adequacy (45 CAPD; 10 nightly automatic peritoneal dialysis, NAPD; 8 intermittent peritoneal dialysis, IPD; 15 standard bicarbonate haemodialysis; 15 high-efficiency-haemodialysis). Urea and creatinine kinetics were analyzed as well as dietary protein intake. In CAPD, a weekly Kt/V of 1.77 was calculated including peritoneal and residual renal clearance (K(pr)t/V). Patients with residual renal function (58% of the study population) had an average residual renal clearance of 3.42 ml/min, presenting lower concentrations of urea nitrogen and creatinine in the plasma. As a consequence, lower percent excretion of urea and creatinine in the peritoneal fluid was observed in comparison to patients without residual renal function. In NAPD the weekly K(pr)t/V was 1.92 and urea nitrogen removal slightly higher than in CAPD patients. In IPD weekly K(pr)t/V was 1.23 and urea nitrogen removal definitely lower than with any other technique. In the haemodialysis groups, despite the higher clearance and a weekly Kt/V higher than 3, the urea nitrogen removal per week was comparable to that obtained in CAPD and NAPD. The concentration profiles in blood appear to be the critical factor in achieving the final target of the treatment, i.e. the excretion of the amount of waste products derived from protein breakdown and other metabolic pathways. Due to constant blood levels in CAPD such a low Kt/V can be adequate while in HD higher efficiency is required. In intermittent treatments in fact, the sudden decrease of the blood levels during the session leads to a minor removal of solutes even in the presence of higher clearances. As a consequence the predialysis levels in the next session will be higher and will permit a higher removal from the beginning, until a steady balance between intake and removal is obtained.