Disposables for blood treatment, and methods of operating the same

A method of preparing a blood treatment apparatus for operation in one of a first blood access mode and a second blood access mode, said apparatus comprising a supply system of treatment fluid, said method comprises:

• obtaining a disposable comprising:
• a blood treatment unit;
• a blood withdrawal connector connected to the blood treatment unit via a blood withdrawal line;
• a blood return connector connected to the blood treatment unit via a blood return line;
• wherein one of the blood withdrawal line and the blood return line comprises a membrane pump arrangement operable to pump blood through the blood treatment unit;
• wherein the membrane pump arrangement comprises first and second blood line branches that are connected at an upstream end and at a downstream end, wherein a first membrane pump is arranged in the first blood line branch, and a second membrane pump is arranged in the second blood line branch;
• connecting the blood treatment unit to the supply system for generating a flow of treatment fluid through the blood treatment unit;
• if the apparatus is to be prepared for operation in the first blood access mode in which the blood withdrawal and blood return connectors are connected to a single access device, manipulating the disposable to block blood flow to and from the first membrane pump, and configuring the second membrane pump to alternately draw blood from the upstream end and pump blood through the downstream end, so as to generate a pulsatile flow of blood through the blood treatment unit;
• and
• if the apparatus is to be prepared for operation in the second blood access mode in which the blood withdrawal and blood return connectors are connected to a first and a second access device, respectively, configuring the first and second membrane pumps to concurrently draw blood from the upstream end and pump blood through the downstream end, so as to generate an essentially continuous flow of blood through the blood treatment unit.

A disposable configured for use in one of a first blood access mode and a second blood access mode during blood treatment, comprising:

• a blood treatment unit for connection to a supply system operable to pump a treatment fluid through the blood treatment unit during said blood treatment;
• a blood withdrawal connector which is connected to the blood treatment unit via a blood withdrawal line;
• a blood return connector which is connected to the blood treatment unit via a blood return line;
• wherein one of the blood withdrawal line and the blood return line comprises a membrane pump arrangement operable to pump blood through the blood treatment unit;
• wherein the membrane pump arrangement comprises first and second blood line branches that are connected at an upstream end and at a downstream end, wherein a first membrane pump is arranged in the first blood line branch, and a second membrane pump is arranged in the second blood line branch;
• wherein each of the first and second membrane pumps comprises a pumping chamber and a flexible member separating the pumping chamber into a blood compartment and a working fluid compartment and being movable within the pumping chamber so as to vary the volume relationship between the blood compartment and the working fluid compartment, wherein the blood compartment is arranged for fluid communication with the upstream and downstream ends, and the working fluid compartment is arranged for fluid communication with the supply system;
• wherein each of the first and second membrane pumps comprises an upstream valve and a downstream valve which are connected for fluid communication with the supply system and controllable to selectively block blood flow on generation of a positive pressure in the treatment fluid;
• and
• wherein the disposable is configured for the first blood access mode by first-type flow directors being fixedly arranged at the upstream and downstream ends to direct the blood via only the second blood line branch, and for the second blood access mode by second-type flow directors being fixedly arranged at the upstream and downstream ends to direct the blood via the first blood line branch and the second blood line branch.