The purpose of this study is to validate the concept of adapted automated PD a modified Peritoneal Equilibration Test (PET), will be performed in children on chronic PD. Instead of a single 4 hour standard dwell, two double mini PET using the same type and total volume of dialysate and the same total dwell time (150min) will be performed in randomised sequence. An double mini test consists of two identical dwells, reflecting routine PD, the other one of a short small dwell followed by a long, large dwell as suggested from adapted PD regimes successfully applied in adult PD patients.

Present peritoneal dialysis treatment is hampered by the limited efficacy of currently applied regimen, mainly consisting of a series of standard dwells with the same amount of dialysate and dwell time. New cycler machines available for routine therapy now allow modification of time and volume of each dwell and thus to individually adapt PD regime. In fact a recent multi-center trial in adult patients suggests that a PD regimen consisting of a sequence of short small dwells followed by large and long lasting dwells in total applying the same amount of dialysate during the same total treatment time substantially improves fluid and toxin removal. Underlying beneficial mechanisms are highly debated. Prior to adaptation of such PD treatment patterns to children on automated PD in the routine clinical setting, the tolerability and biochemical effects need to be demonstrated.

To this end, the Peritoneal Equilibration Test (PET), which is routinely performed in children during a day hospital treatment to analyse peritoneal transport function, will be modified. Instead of a single 4 hour standard dwell, two double mini PET using the same type and total volume of dialysate and the same total dwell time (150min) will be performed in randomised sequence in a total of 15 stable pediatric PD patients treated in four different European pediatric dialysis centres. The conventional double mini PET consists of two identical cycles (fill volume 1 L/m², 75 min), the adapted one of a short, small cycle (0.6 mL/m² BSA, 30 min) followed by a long, large cycle (1.4 mL/m², 120 min). A total of 22 ml of blood will be drawn via a peripheral i.v. line, intraperitoneal pressure, in clinical routine controlled once during a PET, will be measured with each dwell.

The study analyses the time and volume dependent PD transport mechanisms. Patients included may benefit from the detailed analysis of peritoneal membrane function, allowing for optimisation of the individual PD prescription.

Inclusion Criteria:

• PD patients 5-21 years of age
• Stable PD
• Last peritonitis > 4 weeks ago

Exclusion Criteria:

• Polyuria and dehydrated patients (as to the clinical status RR, HR and BCM) not allowing for more than 1.5% glucose content of PD fluid
• Hypoalbuminemia (serum albumin < 25g/l)
• Relevant changes in dialysis regime and diet the three days preceding the study
• Hb < 9 mg/dl
• Pregnancy
• History of repeated hernia or PD fluid leakage
• Intolerability of intraperitoneal pressure of up to 18 cm H2O at 1400ml/m²
• BSA in supine position (e.g. due to organomegaly)
• Any underlying diseases affecting the peritoneal membrane transport function (such as previous surgery with subsequent adhesions and fluid trapping, chronic bowl disease)
• Heart insufficiency
• Patients with catheter dysfunction, i.e. outflow problems (assessed by cycler alarms during the last 2 weeks)