Apparatus for bringing a severely fluid-overloaded patient closer to a normal fluid status, the apparatus comprising a memory and a digital signal processor, comprising a first determination unit configured to determine a first fluid status of the severely fluid-overloaded patient, wherein the first determination unit is configured to determine the fluid status on the basis of measurement data obtained prior or after a treatment session by at least one of: a) an imaging method, preferably chest x-ray imaging and/or inferior vena caval diameter ultrasound imaging, b) biochemical markers, preferably ANP, BNP, nT-pro BNP and/or cGMP, c) a bioimpedance measurement method, particularly a single-frequency bioimpedance measurement, preferably by a vector method, or a multi-frequency bioimpedance measurement, particularly with a BCM, preferably by whole body bioimpedance spectroscopy, d) the ratio between the total body water volume and the extracellular water volume, and a second determination unit configured to determine a second fluid status of the patient once it is determined on the basis of the first fluid status that the patient is not severely fluid-overloaded anymore but is within a range of a normal fluid status, and wherein the second determination unit is configured to determine the second fluid status on the basis of measurement data obtained during a treatment session by at least one of: e) a blood volume measurement method, preferably by blood volume monitoring and more preferably by determining the optical properties in the intravascular compartment, and f) segmental bioimpedance spectroscopy, preferably calf bioimpedance spectroscopy (cBIS) and wherein the apparatus is configured to estimate the dry weight of the patient based on the second fluid status. wherein the first determination unit is configured to determine the fluid status on the basis of measurement data obtained prior or after a treatment session by at least one of: a) an imaging method, preferably chest x-ray imaging and/or inferior vena caval diameter ultrasound imaging, b) biochemical markers, preferably ANP, BNP, nT-pro BNP and/or cGMP, c) a bioimpedance measurement method, particularly a single-frequency bioimpedance measurement, preferably by a vector method, or a multi-frequency bioimpedance measurement, particularly with a BCM, preferably by whole body bioimpedance spectroscopy, d) the ratio between the total body water volume and the extracellular water volume, a) an imaging method, preferably chest x-ray imaging and/or inferior vena caval diameter ultrasound imaging, b) biochemical markers, preferably ANP, BNP, nT-pro BNP and/or cGMP, c) a bioimpedance measurement method, particularly a single-frequency bioimpedance measurement, preferably by a vector method, or a multi-frequency bioimpedance measurement, particularly with a BCM, preferably by whole body bioimpedance spectroscopy, d) the ratio between the total body water volume and the extracellular water volume, and a second determination unit configured to determine a second fluid status of the patient once it is determined on the basis of the first fluid status that the patient is not severely fluid-overloaded anymore but is within a range of a normal fluid status, and wherein the second determination unit is configured to determine the second fluid status on the basis of measurement data obtained during a treatment session by at least one of: e) a blood volume measurement method, preferably by blood volume monitoring and more preferably by determining the optical properties in the intravascular compartment, and f) segmental bioimpedance spectroscopy, preferably calf bioimpedance spectroscopy (cBIS) and wherein the apparatus is configured to estimate the dry weight of the patient based on the second fluid status. e) a blood volume measurement method, preferably by blood volume monitoring and more preferably by determining the optical properties in the intravascular compartment, and f) segmental bioimpedance spectroscopy, preferably calf bioimpedance spectroscopy (cBIS)