Solute removal characteristics of continuous recirculating peritoneal dialysis in experimental and clinical studies

Continuous recirculating peritoneal dialysis (CRPD) was introduced to enhance solute removal efficiency in conventional peritoneal dialysis (PD) therapies such as continuous ambulatory peritoneal dialysis (CAPD). In CRPD, a portion of the dwell dialysate in the patient's peritoneal cavity is drained through a double-lumen catheter and purified by an extracorporeal dialyzer. In this study, solute removal characteristics and safety of CRPD are examined in ex vivo and clinical studies. Recirculation dialysis experiments using nine dogs (13.6 +/- 2.5 kg of body weight) were carried out for 240 min in the ex vivo study, whereas another seven dogs (12.1 +/- 2.8 kg) received conventional peritoneal dialysis (CPD) (120 min dwelling x 2) and six additional dogs (11.9 +/- 2.7 kg) received a Tidal PD (20 min dwelling x 12; 50% of tidal volume ratio) as controls. The ex vivo study revealed that CRPD has a higher efficiency for solute removal than CPD and is equivalent to Tidal PD. In the BUN reduction rate, the 19.4 +/- 5.5% in 240 min CRPD (n = 9) was significantly higher (p < 0.05) than the 3.5 +/- 3.6% in 240 min CPD (n = 7) and equivalent to the 17.3 +/- 4.7% in 240 min Tidal PD (n = 6). Continuous recirculating peritoneal dialysis maintained a low UN level in the peritoneal cavity due to dialysis with an extracorporeal dialyzer. This tendency was also seen in creatinine removal. In the clinical study, CRPD (n = 10) and CPD (n = 5) treatments were used in three renal failure patients. Higher solute removal efficiency was shown in CRPD than in CPD treatments, and the urea peritoneal clearance was 14.1 +/- 4.4 ml/min in CRPD (n = 10), significantly higher (p < 0.05) than the 7.3 +/- 2.1 ml/min in CPD (n = 5). No fibrin formation occurred during CRPD treatments.