An apparatus for continuous renal replacement therapy, comprising: a blood circuit (10, 20, 30, 60) comprising a blood removal line, a treatment unit, and a blood return line, the blood treatment unit comprising a semipermeable membrane, a first chamber, and a second chamber, the semipermeable membrane being configured for separating the first chamber from the second chamber, the blood removal line having a first end destined to be connected to a vascular system of a subject and a second end connected to an inlet port of the first chamber, the blood return line having a first end connected to an outlet port of the first chamber and a second end destined to be connected to the vascular system; a replacement fluid container configured for containing a medical fluid; an infusion line having a first end connected to the replacement fluid container and a second end connected to the blood circuit (10, 20, 30, 60); a blood pump active on the blood circuit; a replacement fluid pump active on the infusion line; a control unit connected to the replacement fluid pump and to the blood pump and configured for performing a rinse-back procedure for restituting blood to a patient, particularly at the end of the treatment, the rinse-back procedure comprising: - conveying blood contained in the blood circuit (10, 20, 30, 60) towards the second end of the blood return line using the medical fluid, characterized in that the rinse back procedure further comprises: - monitoring an amount of fluid present in the replacement fluid container at the time of activation of the rinse-back procedure; - determining a selected rinse-back mode from a group comprising more than one of a first rinse-back mode, a second rinse-back mode, a third rinse-back mode, a fourth rinse-back mode, and a fifth rinse-back mode, wherein the selected rinse-back mode is determined at least based on the amount of the medical fluid present in the fluid container. a blood circuit (10, 20, 30, 60) comprising a blood removal line, a treatment unit, and a blood return line, the blood treatment unit comprising a semipermeable membrane, a first chamber, and a second chamber, the semipermeable membrane being configured for separating the first chamber from the second chamber, the blood removal line having a first end destined to be connected to a vascular system of a subject and a second end connected to an inlet port of the first chamber, the blood return line having a first end connected to an outlet port of the first chamber and a second end destined to be connected to the vascular system; a replacement fluid container configured for containing a medical fluid; an infusion line having a first end connected to the replacement fluid container and a second end connected to the blood circuit (10, 20, 30, 60); a blood pump active on the blood circuit; a replacement fluid pump active on the infusion line; a control unit connected to the replacement fluid pump and to the blood pump and configured for performing a rinse-back procedure for restituting blood to a patient, particularly at the end of the treatment, the rinse-back procedure comprising: - conveying blood contained in the blood circuit (10, 20, 30, 60) towards the second end of the blood return line using the medical fluid, characterized in that the rinse back procedure further comprises: - monitoring an amount of fluid present in the replacement fluid container at the time of activation of the rinse-back procedure; - determining a selected rinse-back mode from a group comprising more than one of a first rinse-back mode, a second rinse-back mode, a third rinse-back mode, a fourth rinse-back mode, and a fifth rinse-back mode, wherein the selected rinse-back mode is determined at least based on the amount of the medical fluid present in the fluid container. - conveying blood contained in the blood circuit (10, 20, 30, 60) towards the second end of the blood return line using the medical fluid, characterized in that the rinse back procedure further comprises: - monitoring an amount of fluid present in the replacement fluid container at the time of activation of the rinse-back procedure; - determining a selected rinse-back mode from a group comprising more than one of a first rinse-back mode, a second rinse-back mode, a third rinse-back mode, a fourth rinse-back mode, and a fifth rinse-back mode, wherein the selected rinse-back mode is determined at least based on the amount of the medical fluid present in the fluid container.