The primary objective of this study is:
\- UFV determined per defined dwells with variable dwell duration, dialysis fluid glucose composition and inflow volumes
The secondary objectives of this study are:
* Mean daily UFV
* Defined laboratory parameter like urea, creatinine, glucose, sodium determined in blood and dialysate during the extended PET (in dialysate additionally determination: phosphate, albumin removal)
* Treatment parameter: performed treatment duration and volume
* Fluid status measured by Body Composition Monitor (BCM)
* Manual IPP determination during the extended PET: At the first half of the dwell (during the first hour) for every 20 min and during the second half after 2h, 3h and 4h dwell time
* Residual renal function (RRF): renal urea and creatinine clearance, 24h urine output, Glomerular filtration rate (GFR)
* Extended PET
* 24 h batch collection (including e.g. total peritoneal clearance)
* Analysis of daily dietetic fluid intake, weight and further parameters documented by the patient in a patient diary
