The standard peritoneal permeability analysis in the rabbit: A longitudinal model for peritoneal dialysis

Objective:The development of an experimental peritoneal dialysis (PD) model in rabbits to investigate peritoneal transport characteristics during a lo ngitudinal follow-up and to assess normal values of these peritoneal transp ort parameters. Design: Peritoneal transport parameters were determined in conscious, unres trained rabbits by standard peritoneal permeability analysis adjusted for r abbits (SPAR). In this test a 1-hour dwell with 3.86% glucose dialysate is used. Dextran 70 (1 g/L) was added to the dialysate to allow calculation of fluid kinetics. Dialysate samples were taken before, 10, and 40 minutes af ter instillation and at the end of the dwell. Blood was drawn at the end of the dwell. Experimental Animals: Eighteen female New Zealand White rabbits (2565 g) we re included for catheter implantation. SPARs were performed in 15 animals; the other 3 were excluded due to complications. Main Outcome:The mass transfer area coefficients (MTACs) of the low molecul ar weight solutes urea (MTAC(urea)) and creatinine (MTAC(cr)) were calculat ed. The clearances of albumin (Cl-alb) and IgG (Cl-lgG), glucose absorption , and fluid transport were computed. Coefficients of intraindividual variat ion (Vc) were calculated for these parameters. Results:The main complications were catheter obstruction and/or dislocation . Five rabbits underwent uncomplicated PD during a 4-week period. Fifteen S PARs in 15 stable rabbits were performed and analyzed to obtain normal valu es. Means and standard deviations of the transport parameters were as follo ws: MTAC(urea) 2.24 +/- 0.57 mL/min, MTAC(cr) 1.61 +/- 0.30 mL/min, Cl-alb 52.9 +/- 17.2 mu L/min, Cl-lgG 44.5 +/- 22.9 mu L/min. The transcapillary u ltrafiltration rate was 0.66 +/- 0.13 mL/min and the lymphatic absorption r ate 0.47 +/- 0.26 mL/min. The parameters of solute transport were upscaled to those in humans using two different methods. MTACs of low molecular weig ht solutes in rabbits and patients were of the same order of magnitude, but the clearance of albumin was approximately four times higher in rabbits th an in patients, and that of IgG eight times. In all rabbits sieving of sodi um was observed. The dialysate/plasma (D/P) of sodium decreased to a minimu m at 40 min (p < 0.003 vs the initial value), followed by a rise to 60 min. The minimal value was 0.884 +/- 0.002. The coefficients of variation calcu lated on 7 rabbits that underwent two or more SPARs were similar to those a ssessed from the patient data. This indicates stability of the model and re producibility of the SPAR. Conclusion:The conscious rabbit model for PD can be used for repeated studi es on peritoneal transport.