The present invention relates to a method for treating the blood of a patient (2), comprising dewatering of the blood of the patient (2) at an adjustable dewatering rate, wherein the position of the patient (2) is determined and the dewatering rate is set and controlled in an open-loop and/or closed-loop manner according to the determined position of the patient (2). The invention further relates to a device for treating the blood of a patient (2), comprising a blood treatment device (1) for dewatering the blood of the patient (2) at an adjustable dewatering rate, characterized by position determining means (40, 42, 44, 46) for determining the position of the patient (2), wherein the dewatering rate can be set and controlled in an open-loop and/or closed-loop manner according to the determined position of the patient.
