Fluid Management Guided by Bioimpedance Analysis in Peritoneal Dialysis(PD) Patients.

1. Purpose: to investigate the effect of bioimpedance analysis(BIA) guided fluid management versus experiential way on clinical outcome in peritoneal dialysis patients. 2. Design: prospective,randomized,controlled,single center study 3. Study hypothesis: Patients on peritoneal dialysis are frequently hypervolemic, which is associated with increasing hazard of death and cardiovascular events. Bioimpedance analysis is a safe, and easy way, which appears to be more useful and sensitive than other techniques for assessing volume status in dialysis patients. Therefore we hypothesize that more concise and strict fluid management guided by BIA may help to improve patients' survival, decrease cardiovascular events and hospitalization rate. 4. Objects: incident and prevalent patients with overhydration status. 1. anticipated cases:240 2. arms: all the patients are randomized into two arms.(BIA group/clinical group) 3. observational time:12 months 5. Primary Outcome: all cause mortality. Secondary Outcomes: technique survival, cardiovascular events, peritonitis, residual renal function.