Abstract: The present invention is an electrical circuit for regulating the average current through and the voltage across a load, such as a rechargeable battery. The circuit includes at least one semiconductor switching device connected in series with the load for controlling the current through the load. A current control loop is provided in the circuit to maintain the average current through the load at a constant level despite changes in the resistance of the load. Also provided is a voltage control loop which acts to limit the voltage across the load to a value below a predetermined voltage level.

Abstract: The present invention is directed to an improved cassette for use in an intravenous infusion pump. The cassette of the present invention includes a cassette body which is capable of being removably secured within a volumetric pump. The cassette body has a volumetric chamber of predetermined volume which is placed in communication with an inlet and an outlet. The volumetric cassette includes an inlet corridor through which fluid may flow into the cassette. The inlet corridor in turn flows into a central corridor which leads directly to the volumetric chamber. The cassette also includes an outlet corridor which is also in communication with the central corridor and, in turn, the volumetric chamber. Fluid will, therefore, exit the volumetric chamber through the outlet corridor by way of the central corridor. The outlet corridor is then connected to the patient infusion line. The cassette of the present invention also includes a plunger which reciprocates within the interior of the volumetric chamber.

Abstract: A system for withdrawing a predetermined volume of fluid from a patient comprises a filter assembly which is connected in line for fluid communication between an artery and a vein of the patient. A pump having a fluid chamber is connected in fluid communication with a filtrate port of the filter. Operation of the pump causes the withdrawal of fluid from the filter and into the pump chamber at a preselected volumetric rate. Periodically, the pump is cycled to expel the withdrawn fluid from the pump chamber. The system further comprises a fluid collection device for collecting the expelled fluids and may include means for replenishing fluids to the patient.

Abstract: A linear peristaltic device for pumping medical solutions to a patient comprises a hinged pivot or hinged attachment between the peristaltic drive mechanism and its associated platen. An IV tube, through which the medical solutions are to be pumped is received and held between the peristaltic drive mechanism and the platen during operation of the device. The device also includes a compliant means which normally urges the peristaltic mechanism toward the platen but which yields, as necessary, to limit the force the peristaltic mechanism can exert against the tube.

Abstract: A linear peristaltic device for pumping medical solutions to a patient comprises a hinged attachment between the peristaltic drive mechanism and its associated platen. An IV tube, through which the medical solutions are to be pumped is received and held between the peristaltic drive mechanism and the platen during operation of the device. The device also includes a compliant means which normally urges the peristaltic mechanism toward the platen but which yields, as necessary, to limit the force the peristaltic mechanism can exert against the tube.

Abstract: An empty container detector for use with a drip chamber comprises a photoelectric transducer associated with the fluid container which generates a variable control signal to alternately indicate whether the light path of the photoelectric transducer is being refracted by a fluid. A second photoelectric transducer is associated with a fluid container above the fluid level in the container to establish a reference signal which is modulated by drops falling into the container and which has a component corresponding to the condition wherein the light path is not refracted or attenuated by the presence of a fluid. Electrical means are provided to connect the first photoelectric transducer to the second photoelectric transducer to linearize and normalize the reference signal with the control signal.