Abstract: An access needle for extracorporeal therapy is equipped with a mount and a sleeve having a metal or magnetic component at its distal end. The mount includes a sensor for detecting when the distal end is pressed against the mount. The sensor is a hall-effect sensor or a proximity sensor. When therapy is begun, the sleeve is rolled up and urged against the mount, exposing the needle for use with the patient. While the sleeve, and the piece of metal or magnet, remains in contact with the sensor, the needle has not been dislodged and therapy may continue. If the needle is dislodged, the sleeve pushes away from mount, moving the metal or magnet away from the sensor. The sensor notes the dislodgement and sends a signal to alert the patient or a caregiver.

Abstract: A dialysis system instrument includes a dialysis instrument, a disposable pumping and valving cassette apparatus operable with pumping and valving actuators of the dialysis instrument, the disposable cassette including an electronic cell and electronics associated with the electronic cell, the electronics configured to determine an electrical property of a solution flowing through the electronic cell of the disposable apparatus.

Abstract: A dialysate testing method in one embodiment includes placing electrical contacts in a dialysate flow path, measuring an electrical property of the dialysate as it flows through the flow path and past the contacts, and determining whether the dialysate has been mixed properly from the detected electrical property. A dialysate testing method in another embodiment includes flowing dialysate past a pair of electrical contacts, calculating a conductivity of the dialysate using an algorithm that takes into account a geometry of the contacts, and using the calculated conductivity to determine if the dialysate has been removed properly.

Abstract: A dialysis fluid heating system includes a plurality of conductive tubes; first and second end caps located at first and second ends of the tubes, respectively, the first end cap including a dialysis fluid inlet and a dialysis fluid outlet, the end caps and the tubes configured such that dialysis fluid can flow from the fluid inlet of the first end cap, through at least one first tube to the second end cap, and through at least one second tube back to the first end cap; a conductive wire wound around an outside of the conductive tubes; and electronics configured to supply power to the conductive wire, the wire forming a primary coil of a transformer, the tubes forming a secondary coil of the transformer.