Apparatus for extracorporeal blood treatment, comprising: a filtration unit (2) having a main compartment (3) and a secondary compartment (4) 5 separated by a semi-permeable membrane (5)； a blood collection line (6) connected to an input of the main compartment (3), and a blood return line (7) connected to an output of the main compartment (8), said blood lines being designed to connect to the system cardiovascular of a patient； a blood pump (11) to control the flow of blood through the blood lines (6, 7)； a line (13) of effluent fluid connected to an outlet of the secondary compartment (4)； one or more infusion fluid lines (15, 21, 25) connected to one of the blood collection line (6) and the blood return line (7), wherein said or said infusion fluid lines comprise a pre-dilution fluid line (15) connected to the blood collection line and a post-dilution fluid line (25) connected to the blood return line； a line (19) of dialysis fluid connected to the inlet of the secondary compartment (4)； means for regulating the flow of fluid (17, 18, 21, 22, 27) through said fluid lines (13, 15, 21, 25, 19), such that the means for regulating the flow of fluid through of said fluid lines comprise a pre-dilution pump (18) to regulate the flow through said pre-dilution fluid line, a post-dilution pump (27) to regulate the flow through said line of post-dilution fluid, and at least one dialysis fluid pump (21) to regulate the flow through said dialysis fluid line； and a control unit (10) configured to: set initial values at one or more fluid flows selected from the group that includes a fluid flow rate (Qeff) through the effluent line (13), a fluid flow rate (Qrep, Qpbp) through the infusion fluid line (15, 21, 25) 35, a fluid flow rate (Qdial) through the dialysis fluid fluid line (27), and a fluid extraction rate ( Qpfr) of the patient, calculate or receive at least one prescribed dose (Dset), said prescribed dose being an objective average value of a flow to be delivered during
