Patent ID: 7540958

Claim:
A device for extracorporeal treatment of blood intended to operate in a mode with a single needle, comprising: a treatment unit having a first compartment and a second compartment, which are separated by a semipermeable membrane, an extracorporeal blood circuit comprising a single needle, an intake line in fluid communication with the first compartment of the treatment unit, and a return line in fluid communication with the first compartment of the treatment unit, a purge line at the outlet of the second compartment, a closure means acting on at least the intake line and the return line in order to generate the alternate sequence of blood intake and return, at least a first chamber in fluid communication with the extracorporeal blood circuit said first chamber defining a first additional blood volume, the first chamber having a variable total content; wherein: the first chamber is rigid and includes at least one movable wall, the device includes a means acting on the first chamber in order to modify the volume of the first chamber, making it possible to store blood during the arterial phase and release blood during the venous phase, wherein the first chamber includes an opening to the outside, said opening having a hydrophobic diaphragm associated with said opening, said hydrophobic diaphragm being configured to remove any undesirable air bubble present in the first chamber.