USE OF INTRAPERITONEAL PRESSURE, ULTRAFILTRATION AND PURIFICATION DWELL TIMES FOR INDIVIDUAL PERITONEAL-DIALYSIS PRESCRIPTION IN CHILDREN

Tolerance of peritoneal dialysis is, in a part, dependent on intraperi toneal dialysate volume. Measurement of intraperitoneal pressure (IPP) in cm of water is easy to perform especially with the twin bag Y set (Baxter). Today we use IPP for following surgical catheter implantatio n (delaying, starting and progressing with peritoneal dialysis) and fo r optimizing ultrafiltration and purification. Efficiency of peritonea l dialysis is dependent on adequate ultrafiltration (UF) and on adequa te purification (solute clearances). These two goals seem apparently c onflicting in terms of duration of dwells: short dwell time enhances U F capacity and conversely long dwell time enhances solute clearance. P eritoneal equilibration test (PET) allows an approach to the ultrafilt ration time: the point at which the overtime dialysate urea saturation and glucose desaturation curves cross, called APEX time. PET allows a lso an approach of the purification time: the point at which dialysate (D) to plasma (P) concentration ratios over time are high. Because th e value of phosphate as uremic factor of morbidity, we have chosen the time for D/P phosphate equal to 0.6 as a purification phosphate dwell time (PPT). A total of 17 patients were studied, over a five-year per iod allowing 142 determinations. APEX times (range 18 to 71 min) and P PT (range 105 to 238 min) were spread over a wide distribution. PPT an d APEX times were significantly shorter in children younger than 3 yea rs of age than in children older than 10 years of age. PPT were nearly four times longer than APEX times. The knowledge of these conflicting ultrafiltration and purification times should help, in our view, in t he individual choice of the PD modality: if UF is the major goal, shor t dwell times should be used (automatic PD); if purification is the ma jor goal, long dwell times should be used (CAPD); if both are the targ et goal, tidal PD should be discussed.