A fluid separation device includes a centrifuge in which a fluid is separated into at least two components, with an interface therebetween. At least a portion of one of the separated fluid components is removed from the centrifuge and flows through a vessel. Light is reflected off of the separated fluid component in the vessel and received and analyzed to determine its main wavelength. If the main wavelength is higher than a maximum value, a target location of the interface is changed. If the main wavelength is less than the maximum value, then the location of the interface is compared to the target location. When the interface is sufficiently close to the target location, the optical density of the separated fluid component in the vessel is compared to a minimum value. If the optical density is less than the minimum value, the target location of the interface is changed.

Dialysis systems comprising actuators that cooperate to perform dialysis functions and sensors that cooperate to monitor dialysis functions are disclosed. According to one aspect, such a hemodialysis system comprises a user interface model layer, a therapy layer, below the user interface model layer, and a machine layer below the therapy layer. The user interface model layer is configured to manage the state of a graphical user interface and receive inputs from a graphical user interface. The therapy layer is configured to run state machines that generate therapy commands based at least in part on the inputs from the graphical user interface. The machine layer is configured to provide commands for the actuators based on the therapy commands.

Blood in a separation chamber is separated into a red blood cell layer, a plasma constituent, and a mononuclear cell-containing layer. A portion of the plasma constituent exits the chamber via a plasma outlet, while a first portion of the red blood cell layer exits via a red blood cell outlet. A second portion of the red blood cell layer exits the chamber via the red blood cell outlet and is collected. At least a portion of the collected red blood cell layer may then be conveyed to the chamber via the red blood cell outlet to convey at least a portion of the mononuclear cell-containing layer out of the chamber via the plasma outlet for collection. A second portion of the plasma constituent may be conveyed out of the chamber via the plasma outlet to more fully collect the mononuclear cell-containing layer without the use of collected plasma.

Dialysis systems are disclosed comprising new fluid flow circuits. Systems may include blood and dialysate flow paths, where the dialysate flow path includes balancing, mixing, and/or directing circuits. Dialysate preparation may be decoupled from patient dialysis. Circuits may be defined within one or more cassettes. The fluid circuit fluid flow paths may be isolated from electrical components. A gas supply in fluid communication with the dialysate flow path and/or the dialyzer able to urge dialysate through the dialyzer and urge blood back to the patient may be included for certain emergency situations. Fluid handling devices, such as pumps, valves, and mixers that can be actuated using a control fluid may be included. Control fluid may be delivered by an external pump or other device, which may be detachable and/or generally rigid, optionally with a diaphragm dividing the device into first and second compartments.

Embodiments are described for separating collecting components from a multi-component fluid such as whole blood. Some embodiments provide for controlling the amount of a component, such as platelets, introduced into a separation chamber to ensure that the density of fluid in the separation chamber does not exceed a particular value. This may provide for collecting purer components. Other embodiments may provide for determining a chamber flow rate based on a concentration of a component in the multi-component fluid, which may then be used to determine a centrifuge speed, to collect purer concentrated components.

A hemodialysis system is disclosed. The hemodialysis system includes a dialyzer, a saline container including saline, and a disposable set comprising a blood pumping tube fluidly connected to a first end of the dialyzer, an arterial line fluidly connected to a first end of the blood pumping tube, a venous line fluidly connected to a second end of the dialyzer, a saline line fluidly connected to the blood pumping tube and the saline container, and a dialyzer line fluidly connected to a second end of the blood pumping tube and a second end of the dialyzer. The hemodialysis system also includes a dialysis instrument comprising an arterial line clamp, a venous line clamp, and a saline valve. The saline rinses blood out of the arterial line when the venous line clamp is closed, the arterial line clamp is opened, and the saline value is opened.

Blood in a separation chamber is separated into a red blood cell layer, a plasma constituent, and a mononuclear cell-containing layer. A portion of the plasma constituent exits the chamber via a plasma outlet, while a first portion of the red blood cell layer exits via a red blood cell outlet. A second portion of the red blood cell layer exits the chamber via the red blood cell outlet and is collected. At least a portion of the collected red blood cell layer may then be conveyed to the chamber via the red blood cell outlet to convey at least a portion of the mononuclear cell-containing layer out of the chamber via the plasma outlet for collection. A second portion of the plasma constituent may be conveyed out of the chamber via the plasma outlet to more fully collect the mononuclear cell-containing layer without the use of collected plasma.

Embodiments are described for separating/collecting components from a multi-component fluid such as whole blood. Some embodiments provide for controlling the amount of a component, such as platelets, introduced into a separation chamber to ensure that the density of fluid in the separation chamber does not exceed a particular value. This may provide for collecting purer components. Other embodiments may provide for determining a chamber flow rate based on a concentration of a component in the multi-component fluid, which may then be used to determine a centrifuge speed, to collect purer concentrated components.

A hemodialysis system is disclosed. The hemodialysis system includes a disposable set including a blood pumping tube, a fresh dialysate pumping tube, and a spent dialysate pumping tube. The hemodialysis system also includes a dialysis instrument including a blood pump head, a fresh dialysate pump head, a spent dialysate pump head, a first motor positioned and arranged to operate the blood pump head, a second motor positioned and arranged to operate the fresh dialysate pump head, and a third motor positioned and arranged to operate the spent dialysate pump head. When the disposable set is loaded into the dialysis instrument, the blood pumping tube comes into registry with the blood pump head, the fresh dialysate pumping tube comes into registry with the fresh dialysate pump head, and spent dialysate pumping tube comes into registry with the spent dialysate pump head.

A system for detecting whether a vascular access has been interrupted in an arrangement in which two catheters or needles are present in a blood vessel, fistula or graft. A fluid line leading to a pump is connected via a first connector to a first indwelling catheter, and a fluid line leading from a pump is connected via a second connector to a second indwelling catheter. Each connector is equipped with an electrode in contact with the lumen of the connector, the electrodes electrically connected to an electronic circuit that measures the impedance or conductivity of fluid between the first connector and second connectors via a fluid path through the blood vessel, fistula or graft. An electronic controller receives the impedance or conductivity data and processes the data to determine whether a vascular access disconnection has occurred. The processing may involve filtering the signal received by the controller, and/or setting provisional flags for a disconnection event that may be cleared if the signal changes before the expiration of a counter.