Intraperitoneal hydrostatic pressure and flow characteristics of peritoneal catheters in automated peritoneal dialysis.

BACKGROUND In automated peritoneal dialysis (APD) one of the most important factors that influence the efficiency of the treatment is the total volume of dialysate infused per session and the dwell time. This study is aimed at examining the relationships between i.p. pressure (IPP), dialysate flow characteristics, and different dialysate fill volumes in order to optimize APD. METHODS We studied 20 patients who received APD, with the standard fill volume (2 l, A), or individualized fill volumes based on the patient's body surface area (2.5 l/BSA/1.73 m, B) or on body weight (40 ml/kg body weight, C). The patient's tolerance to a given fill volume was evaluated by measuring IPP, and catheter flow characteristics were evaluated by an automated machine. RESULTS IPP increased with the increase of the infused volume of dialysate (P < 0.05) and tended towards a positive relationship with the patient's body mass index (BMI: A vs IPP: R = 0.39, P = 0.0019; B vs IPP: R = 0.66, P = 0.0012; C vs IPP R = 0.55, P = 0.009). We also found a relationship between fill volume, BMI and IPP: IPP = 1.0839 + 0.53 (beta) x BMI + 0.211 (beta) x fill volume (R = 0.65; r(2) = 0.40 P < 0.01). The mean IPP with different dialysate fill volumes tended to be related to the volume of dialysate drained at the transition point (R = 0.37; P < 0.05). The pre-transition flow rate/mean IPP ratio tended towards a positive relationship with the volume of dialysate drained at the transition point (R = 0.35, P < 0.05), the transition time (R = 0.34; P < 0.05) and a negative one with the transition volume (R = -0.35, P = 0.05). CONCLUSION It is possible to customize APD, where the tidal percentage coincides with the transition point for a given catheter and a specific initial dialysate fill volume, the tolerance of which can be measured by assessing IPP.