The disclosed subject matter relates to extracorporeal blood processing or other processing of fluids. Volumetric fluid balance, a required element of many such processes, may be achieved with multiple pumps or other proportioning or balancing devices which are to some extent independent of each other. This need may arise in treatments that involve multiple fluids. Safe and secure mechanisms to ensure fluid balance in such systems are described.

Systems, methods, and/or apparatuses may be operative to perform a dialysis process that includes a displacer infusion process. In one embodiment, a method for determining a displacer compound may include constructing a plurality of target protein quantitative structure-activity relationship (QSAR) models, one for each of the plurality of binding sites, analyzing a set of candidate compounds using the plurality of QSAR models to determine a set of at least one potential compound with an affinity for binding to each of the plurality of binding sites, and selecting at least one displacer compound from the set of at least one potential compound. Other embodiments are described.

A dialysis system is provided that includes a dialysis machine and a potassium sensing device that is configured to measure the concentration of potassium in the patient's blood, in spent dialysate resulting from treating the patient, or in both. The potassium sensing device can be configured to generate a sensed value of the concentration of potassium. A control and computing unit, including a processor and a memory, is configured to receive the sensed value, compare the value with one or more values stored in the memory, and generate a control signal based on the comparison. A potassium infusion circuit uses the control signal to infuse supplemental potassium solution into the treatment dialysate, a replacement fluid, or both. The memory can include stored patient-historical and population data.

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.

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.

Techniques and apparatuses for determining an estimated cardiac output for a patient during dialysis treatment are described. In one embodiment, for example, an apparatus may include a memory and logic coupled to the memory. The logic may be configured to determine an upper body oxygen consumption for a patient, determine, during a dialysis process: a hemoglobin concentration and a venous oxygen saturation measured via an optical blood monitor operably coupled to an extracorporeal circuit of a dialysis system performing the dialysis process; an arterial oxygen saturation measured via a pulse oximeter operably coupled to the extracorporeal circuit; an arterial-venous oxygen content difference based on the arterial oxygen saturation and the venous oxygen saturation; and an upper body blood flow (UBBF) as (upper body oxygen consumption)/(arterial-venous oxygen content difference), and determine a treatment recommendation based on the upper body blood flow. Other embodiments are described.

The described technology may include processes to model acid-base homeostasis in normal patients and under acid-base disorder conditions. In one embodiment, a method may include an acid-base homeostasis analysis process. The method may include, via a processor of a computing device, providing an acid-base model configured to model acid-base homeostasis of a patient, the acid-base model comprising a patient model, a dialyzer model, and an extracorporeal CO.sub.2 removal device (ECCO.sub.2RD), and determining predicted patient information using the acid-base model. Other embodiments are described.

Embodiments of the disclosure provide a method for determining beginning blood volume of a patient during dialysis (e.g., hemodialysis). Ultrafiltration rates are determined at different time stamps during dialysis by obtaining a blood flowrate measurement and hematocrit measurements at input port and output port of a dialyzer connected to the patient. The flowrate and hematocrit measurements are used to determine fluid removed from the patient during dialysis. The ultrafiltration rates and fluid removed from the patient are used to determine the beginning blood volume of the patient.

A method that regulates supply of substituate in an extracorporeal blood treatment with an extracorporeal blood treatment apparatus comprising a dialyzer divided by a semipermeable membrane into a blood chamber and a dialyzing fluid chamber and a device for supplying substituate. An extracorporeal blood treatment apparatus that includes a device for regulating supply of substituate. Regulation of supply of substituate in the extracorporeal blood treatment takes place as a function of the rheological loading of the dialyzer. To regulate supply of substituate during extracorporeal blood treatment, rheological loading of the dialyzer is determined from transmembrane pressure on the dialyzer and flow resistance of the dialyzer and substituate rate is increased or reduced according to the loading. The selection of dialyzer parameters or blood parameters is therefore no longer necessary and the distinction between pre-dilution and post-dilution is also made obsolete.

In embodiments of the invention, there is provided a dialyzer or filter comprising hollow fibers, in which blood flows on the exterior of the hollow fibers, and dialysate or filtrate may flow on the inside. The external surfaces of the hollow fibers may have properties of smoothness and hemocompatibility. The fiber bundle may have appropriate packing fraction and may have wavy fibers. Optimum shear rates and blood velocities are identified. Geometric features of the cartridge, such as pertaining to flow distribution of the blood, may be different for different ends of the cartridge. Air bleed and emboli traps may be provided. Lengthened service life may be achieved by combinations of these features, which may permit additional therapies and applications or better economics.