Blood treatment device comprising: a blood treatment unit (20) having an inlet (21) and an outlet (22), a blood collection line (11) connected to the inlet (21) of the unit (20) of blood treatment, the blood collection line (11) having a first branch line (13) and a second branch line (14) connected in parallel with the first branch line (13), a line (12) blood return connected to the outlet (22) of the blood treatment unit (20), a first pump (40) connected in the first branch line (13) so that the first line (13) branch is divided into a section (15) upstream and a section (16) downstream, a second pump (50) connected in the second branch line (14) so that the second branch line (14) is divided in a section (17) upstream and a section (18) downstream, characterized by a valid Vula (6) configured to: - open the section (15) upstream and close the section (16) downstream of the first branch line (13), and close the section (17) upstream and open the section (18 ) downstream of the second branch line (14), when the valve (6) moves to a first position (DN-P1), and - close the section (15) upstream and open the section (16) downstream of the first branch line (13), and open the section (17) upstream and close the section (18) downstream of the second branch line (14), when the valve (6) moves to a second position (DN-P2).Dispositivo de tratamiento de sangre que comprende: una unidad (20) de tratamiento de sangre que tiene una entrada (21) y una salida (22), una línea (11) de extracción de sangre conectada a la entrada (21) de la unidad (20) de tratamiento de sangre, teniendo la línea (11) de extracción de sangre una primera línea (13) de ramificación y una segunda línea (14) de ramificación conectada en paralelo con la primera línea (13) de ramificación, una línea (12) de retorno de sangre conectada a la salida (22) de la unidad (20) de tratamiento de sangre, una primera bomba (40) conectada en la primera línea (13) de ramificación de manera que la primera línea (13) de
