An apparatus peritoneal dialysis (1) comprising an automated peritoneal dialysis cycler (3) programmed to run a treatment session including a plurality of cycles, each cycle including a fill phase, a dwell phase and a drain phase of a peritoneal cavity of a patient (P), the treatment session lasting at most 720 min； the cycler (3) has a patient line (54) in communication with the patient (P), a source (S) of treatment fluid which includes an osmotic agent, a pump (5) to circulate the treatment fluid and a control system (74) configured to drive the cycler (3) to deliver the treatment session. The control system (74) is programmed to run a fill phase of a first cycle delivering a first treatment fluid to the patient, the first treatment fluid having a first concentration of the osmotic agent； subsequently to the first cycle, to run a fill phase of a second cycle delivering a second treatment fluid to the patient, the second treatment fluid having a second concentration of the osmotic agent different from the concentration of the first treatment fluid； subsequently to the second cycle, to run a fill phase of a third cycle delivering a third treatment fluid to the patient, the third treatment fluid having a third concentration of the osmotic agent different from the concentration of the second treatment fluid. The second concentration of the osmotic agent is lower than the first concentration of the osmotic agent and the third concentration of osmotic agent is higher than the second concentration of osmotic agent.La présente invention décrit un appareil de dialyse péritonéale (1) comprenant un dispositif de cyclage de dialyse péritonéale automatisée (3) programmé pour exécuter une session de traitement comprenant une pluralité de cycles, chaque cycle comprenant une phase de remplissage, une phase de maintien et une phase de drainage d'une cavité péritonéale d'un patient (P), la session de traitement durant au plus 720 min； le dispositif de cyclage (3) possédant une con
