The present invention generally relates to hemodialysis and similar dialysis systems, including a variety of systems and methods that would make hemodialysis more efficient, easier, and/or more affordable. One aspect of the invention is generally directed to new fluid circuits for fluid flow. According to one aspect, a blood pump is configured to pump blood to a dialyzer of a hemodialysis apparatus, the blood pump comprising a pneumatically actuated or controlled reciprocating diaphragm pump. In an embodiment, the diaphragm of the pump comprises a flexible membrane formed or molded to generally conform to a curved inner wall of a pumping chamber or control chamber of the pump, wherein the diaphragm is pre-formed or molded to have a control side taking a convex shape, so that any elastic tension on the diaphragm is minimized when fully extended into a control chamber of the pump. In another aspect, a system for monitoring the adequacy of blood flow in a blood line of the hemodialysis apparatus allows a controller to suspend dialysate pumping operations if the adequacy of blood flow in the blood line is sub-optimal, and to present information on a display on the quality of blood flow in the blood line.

Automated control mechanisms and methods for controlling fluid flow in a hemodialysis apparatus are described. The methods can involve a controller receiving information from a pressure sensor in a control chamber of a reciprocating diaphragm-based blood pump and causing the application of a time-varying pressure waveform on a diaphragm of the blood pump during a fill-stroke of the blood pump. The controller can be configured and programmed to monitor a pressure variation in the control chamber measured by the pressure sensor and to compare the measured pressure variation to a pre-determined value. Based on such comparison, the controller can initiate a procedure to pause or stop a dialysate pump of the hemodialysis apparatus if the magnitude of the measured pressure variation deviates from the pre-determined value.

Hemodialysis and similar dialysis systems including a variety of systems and methods that make hemodialysis more efficient, easier, and/or more affordable, and include new fluid circuits for fluid flow in hemodialysis systems and a reciprocating diaphragm pump for pumping fluids. The reciprocating diaphragm pump includes a flexible diaphragm, a first rigid body having a curved pumping chamber wall, a second rigid body having an opposing curved control chamber wall. The diaphragm is interposed between the pumping chamber wall and the control chamber wall to define a pumping chamber and a control chamber. The diaphragm of the pump has a peripheral bead arranged to locate the diaphragm between the first rigid body and the second rigid body and a diaphragm body having a curved, semi-spheroid or domed shape. The diaphragm is pre-formed or molded so that during a delivery stroke of the pump, the elastic force of the diaphragm resisting its deployment into the pumping chamber prevents a peripheral portion of the diaphragm body from fully contacting the pumping chamber wall.

Systems for monitoring fluid flow in an extracorporeal blood circuit are described. The blood circuit of such systems can include plod pump having a pumping chamber of the blood pump separated from a control chamber of the blood pump by a flexible diaphragm. The control chamber can be configured to transmit positive or negative pressure to operate the diaphragm. The system can include a pressure sensor configured to measure pressure in the control chamber of the blood pump, and a controller configured to receive information from the pressure sensor and to control the delivery of pressure to the control chamber of the blood pump. The controller can also be configured to cause the application of a time-varying pressure waveform on the blood pump diaphragm during a fill-stroke of the blood pump, and to monitor a pressure variation in the control chamber measured by the pressure sensor. When so configured, such controller can transmit a value representing a magnitude of the measured pressure variation to a display associated with the extracorporeal blood circuit.

A cylinder-piston unit with load-dependent damping includes a piston longitudinally displaceable in a cylinder. The piston has a first piston channel and a second piston channel, which each connect a compensation space on one side of the piston to a displacement space side on an opposite side of the piston. On the displacement space side a throttle channel connects one first piston channel to the piston lateral surface. On its displacement space side the piston has a piston journal, which carries a resiliently deformable piston disc. The piston disc is displaceable and covers the throttle channel at least partially. The displacement space side has at least one relief portion deviating from a piston end face plane. The relief portion is delimited on a number of sides by a plurality of boundary lines running concentrically with respect to the central axis. Each of these boundary lines can be differentiated continuously.

A cylinder-piston unit with load-dependent damping includes a piston longitudinally displaceable in a cylinder. The piston has a first piston channel and a second piston channel, which each connect a compensation space on one side of the piston to a displacement space side on an opposite side of the piston. On the displacement space side a throttle channel connects one first piston channel to the piston lateral surface. On its displacement space side the piston has a piston journal, which carries a resiliently deformable piston disc. The piston disc is displaceable and covers the throttle channel at least partially. The displacement space side has at least one relief portion deviating from a piston end face plane. The relief portion is delimited on a number of sides by a plurality of boundary lines running concentrically with respect to the central axis. Each of these boundary lines can be differentiated continuously.

Automated control mechanisms and methods for controlling fluid flow in a hemodialysis apparatus are described. The methods can involve a controller receiving information from a pressure sensor in a control chamber of a reciprocating diaphragm-based blood pump and causing the application of a time-varying pressure waveform on a diaphragm of the blood pump during a fill-stroke of the blood pump. The controller can be configured and programmed to monitor a pressure variation in the control chamber measured by the pressure sensor and to compare the measured pressure variation to a pre-determined value. Based on such comparison, the controller can initiate a procedure to pause or stop a dialysate pump of the hemodialysis apparatus if the magnitude of the measured pressure variation deviates from the pre-determined value.

Systems for monitoring fluid flow in an extracorporeal blood circuit are described. The blood circuit of such systems can include plod pump having a pumping chamber of the blood pump separated from a control chamber of the blood pump by a flexible diaphragm. The control chamber can be configured to transmit positive or negative pressure to operate the diaphragm. The system can include a pressure sensor configured to measure pressure in the control chamber of the blood pump, and a controller configured to receive information from the pressure sensor and to control the delivery of pressure to the control chamber of the blood pump. The controller can also be configured to cause the application of a time-varying pressure waveform on the blood pump diaphragm during a fill-stroke of the blood pump, and to monitor a pressure variation in the control chamber measured by the pressure sensor. When so configured, such controller can transmit a value representing a magnitude of the measured pressure variation to a display associated with the extracorporeal blood circuit.

A hemodialysis apparatus comprising diaphragm pumps for the movement of both dialysate and blood, and under the control of a controller, is capable of detecting blood flow conditions that give rise to an alarm and implement procedures to adjust, pause, or halt the pumping of dialysate and/or blood. The controller can direct the application of a time-varying pressure to fluid in the control chamber of a blood pump, and monitor the resulting pressure waveform during a fill stroke of the blood pump. A deviation of the measured pressure variation from an expected value can give rise to an alert to a user and to the initiation of an adjustment, pause, or cessation of the dialysate pump's activity.

Hemodialysis and similar dialysis systems including a variety of systems and methods that make hemodialysis more efficient, easier, and/or more affordable, and include new fluid circuits for fluid flow in hemodialysis systems and a reciprocating diaphragm pump for pumping fluids. The reciprocating diaphragm pump includes a flexible diaphragm, a first rigid body having a curved pumping chamber wall, a second rigid body having an opposing curved control chamber wall. The diaphragm is interposed between the pumping chamber wall and the control chamber wall to define a pumping chamber and a control chamber. The diaphragm of the pump has a peripheral bead arranged to locate the diaphragm between the first rigid body and the second rigid body and a diaphragm body having a curved, semi-spheroid or domed shape. The diaphragm is pre-formed or molded so that during a delivery stroke of the pump, the elastic force of the diaphragm resisting its deployment into the pumping chamber prevents a peripheral portion of the diaphragm body from fully contacting the pumping chamber wall.